AU2002301429B2 - A Reinforcing Fibre, a Process For Making a Reinforcing Fibre, A Process For Making A Curable Composite, A Curable Composite, A Cured Composite, A Method Of Applying A Composite and A Method Of Moulding A Composite - Google Patents

Description

S&F Ref: 576210AUD2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant Actual Inventor(s): Address for Service: Invention Title: Peter Clifford Hodgson 31 Speers Street Speers Point New South Wales 2284 Australia Peter Clifford Hodgson Spruson Ferguson St Martins Tower,Level 31 Market Street Sydney NSW 2000 (CCN 3710000177) A Reinforcing Fibre, a Process for Making a Reinforcing Fibre, a Process for Making a Curable Composite, a Curable Composite, a Method of Applying a Composite and a Method of Moulding a Composite The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845c A REINFORCING FIBRE, A PROCESS FOR MAKING A REINFORCING FIBRE, A PROCESS FOR MAKING A CURABLE COMPOSITE, A CURABLE COMPOSITE, A CURED COMPOSITE, A METHOD OF APPLYING A COMPOSITE AND A METHOD OF MOULDING A COMPOSITE Technical Field This invention relates to a reinforcing fibre, a process for making a reinforcing fibre, a process for making a plurality of reinforcing fibres, a reinforcing fibre for a curable resin made by the process of the invention, a cured composite, a curable composite, a process for making a cured composite, a method of applying a composite to a surface, and a method of moulding a composite. The invention also relates to .a process for the removal of sizing agent from a surface of a reinforcing fibre.

Background Art When fibre reinforced vinyl functional/free radical initiated resins such as Unsaturated Polyester or Vinyl Ester resins are applied to an open mould, they require mechanical consolidation to remove entrapped air. There are two reasons for removing air. The first is to optimize the mechanical strength of the composite, and the second is to improve the chemical resistance. This is also true for epoxy resin composite laminates.

The present art is to 1. spray chopped glass rovings into the resin fan before deposition, or 2. to apply sheets of fabric reinforcement to the mould and then to wet these out with resin, or 3. to pre impregnate the fabric reinforcement with resin prior to placing it on the mould.

All these procedures require some form of mechanical consolidation of the applied laminate to remove entrapped air. To that end, for example, glass fibre swimming pools are usually rolled so as to expel any entrapped air from the fabric.

[R:\LIBXX\NlcovN\Hodgson]DivisionalAUcompleteSpeci2002Octoberl I.doc:JFM Relatively short fibres are normally used in method whilst relatively long fibres are normally used in methods and Method does not yield composites of high strength compared with methods 2 and 3.

In the current art it is not desirable that the fibres are intimately bonded to the resin matrix. All that is required is that there is sufficient bonding so that the applied stresses can be transmitted to the fibres.

A large proportion of the fibres are held in position by mechanical friction between the fibres and the cured resin. They are free to slide relative to the resin matrix when the composite is strained sufficiently. One can hear this slipping with the aid of a microphone. When the composite ruptures there are an abundance of fibres protruding from the ruptured surfaces. The sizing on glass rovings interferes with glass to matrix bonding.

The reason the current art performs is due largely to the length of the fibres. Typically fibre length ranges from 12mm to tens of meters in the case of filament winding and pultrusion and woven rovings. If one hammer mills these reinforcements to less than 4mm and incorporates them into a UPE or VE laminating resin by conventional processes the resulting composite has poor physical properties.

Typically tensile strength is below 65MPa and it has minimal resistance to crack propagation.

The tensile strength of the resin matrix is greater than the tensile strength of the composite.

This comes about by the fact that the reinforcement is too short to be mechanically locked into the matrix. There is little resistance to crack propagation and such composites are not only weak but are also brittle and have very poor impact resistance.

In the literature there is mentioned the CRITICAL LENGTH of a fibre incorporated in a composite. For fibreglass, the critical length is about 2mm lmm. The critical length is the minimum length of a bonded fibre that will break in a composite due to applied strain.

Crack propagation in short fibre composites is a problem, because using standard laminating resins stress fields are very concentrated. When rupture occurs in brittle 1. [R:\LIBXX\NicovN\Hodgson]DvisionalAUcompleteSpeci2002octobfI I .doc:JFM 3 matrix short fibre composites the component suffers brittle failure, the part having poor impact resistance.

In summary 1. The current surface treatment of fibres is inadequate for short fibre composites.

2. Brittle laminating resins do not provide adequate impact resistance.

3. For optimum chemical/environmental resistance non air inhibited resins are preferred for short fibre composites made according to this patent.

The conventional surface treatment of fibres is inappropriate for short fibre composites. There accordingly exists a need for an improved surface treatment for short fibres.

There also exists a need for short reinforcing fibres that are suitable for the manufacture of composites of improved strength in terms of one or more of impact resistance, tensile strength and flexural strength.

There accordingly exists a need for an improved manufacturing technique, which facilitates or enables a higher rate of deposition of the constituents of the composite, without the inclusion of a large number of air bubbles.

Commercial glass fibre is normally sold with a number of compounds already applied to the surfaces of individual fibres. One group of such compounds is what is referred to as a sizing agent. A sizing agent is normally applied to fibres to improve their stiffness, integrity, in order to facilitate their handling or processing (see Richard J Lewis Sr: Hawley's Condensed Chemical Dictionary, 1 2 th Edition, Van Northrand Reinhold, 1993).

As a sizing agent, compounds such as polyvinyl acetate (PVA) and ethylene vinyl acetate (EVA) are frequently used.

PVA is the sizing agent of choice for most glass rovings. The fibreglass industry uses PVA also because it acts as a release agent preventing fibreglass products from adhering to moulds. As a release agent, it is much more effective than waxes or polymeric compounds.

i. [R:\LIBYX\NicovN \Hodgson]DivisionalAUcornpleteSpeci2002OctoberI I.doc:JFM I There is therefore relatively poor adhesion between the resin matrix and glass fibres sized with PVA. This is evidenced by the critical length which is of the order of 2 mm or more.

It is well known that sizing agents interfere with resin to glass bonding. The more sizing, the greater the interference. For this reason, a coupling agent is usually also applied to commercially available glass fibre, as part of the sizing solution, in an effort to improve bonding between the glass fibres and the resin.

Coupling agents such as silanes and titanates are frequently used. According to Chemical Additives for the Plastics Industry, page 57, coupling agents are used to improve the strength of the resin and to control the rheology of the composite during processing. The coupling and polymerizing of the coupling agent described in this patent has a profound affect on the rheology of the liquid composite allowing resin to fibre ratios of less than 2:1. These liquid composites are still sprayable and pumpable using standard fiberglass depositors and injection moulding systems. According to Modern Plastics: Plastics Handbook; McGraw-Hill, Inc; 1994; p 99, the use of coupling agents result in improved bonding and upgraded mechanical and electrical properties. This is not completely true as it implies that more coupling agent gives better strength. If the fibres are too well bonded to a brittle resin matrix then the properties of the composite are very sensitive to surface or internal imperfections especially scratches, nicks and cracks.

Objects of the Invention It is an object of this invention to overcome or substantially ameliorate at least one of the above disadvantages.

Another object of the invention is to address one or more of the aforementioned needs.

Objects of this invention include providing a reinforcing fibre, a process for making a reinforcing fibre, a process for making a plurality of reinforcing fibres, a reinforcing fibre for a curable resin made by the process of the invention, a cured composite, a curable composite, a process for making a cured composite, a method of applying a composite to a surface, and a method of moulding a composite.

Disclosure of Invention 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002October 1 .doc:JFM According to a first aspect of the invention, there is provided a reinforcing fibre having a surface with no sizing agent thereon, wherein said surface of said reinforcing fibre is completely coated with a polymerised coupling agent and said fibre has a maximum fibre length of 6 mm.

For purposes of the manufacture of a glass fibre composite, the fibre is preferably substantially inorganic or is inorganic. The glass fibre may have no sizing agent thereon or it may be initially coated with a sizing agent. The sizing agent, if present, may be removed from the surface of a fibre. Thus the process of removing sizing agent from the surface of a fibre may comprise removing sizing agent from the surface of the fibre. The step of removing may be accomplished by chemically removing and/or by dissolving the sizing agent. The step of removing should be conducted so as not to damage the mechanical properties of the fibre (hence for glass fibres the removing is usually not conducted in the presence of alkali). Conveniently the fibre may be suitable for use with a resin which is substantially organic or which is organic. To facilitate coupling between the substantially inorganic fibre and the substantially organic resin or between the inorganic fibre and the organic resin, the coupling agent may comprise a plurality of molecules each having a first end adapted to bond to the fibre and a second end which is adapted to bond to the resin.

The coupling agent may conveniently be selected from the group consisting of a polymerisable coupling agent and a coupling agent which has been at least partially polymerised before application thereof to the fibre. Preferably, the coupling agent has been at least partially polymerised after application thereof to the fibre.

At least one of the fibre, the resin and the coupling agent may be selected so as to yield a composite of high impact resistance. Alternatively or additionally, at least one of the fibre, the resin and the coupling agent may be selected so as to yield a composite of high tensile strength. Alternatively or additionally, at least one of the fibre, the resin and the coupling agent may be selected so as to yield a composite of high flexural strength.

The coupling agent conveniently be selected from the group consisting of a silane, an organic metal ligand and combinations thereof. The coupling agent maybe a titanate, a zirconate or a combination thereof.

The fibre may have a surface which may be completely coated with a coupling agent for coupling said fibre with a substantially organic resin when [R:\LIBXX]04164.doc:aak cured or with an organic resin when cured, said coupling agent being at least partially polymerised. The coupling agent may be selected from the group consisting of a polymerised or partially polymerised silane, a polymerised or partially polymerised organic metal ligand and combinations thereof. The surface of the fibre may be pretreated with a metal oxide before application of the coupling agent thereto. The metal oxide may be selected from iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide and zirconium dioxide.

According to another aspect of the invention, there is provided a process for making a reinforcing fibre suitable for use in reinforcing a composite made of the fibre and a resin, said process including the step of substantially removing or removing any sizing agent previously applied to the surface of the reinforcing fibre.

Said process may conveniently include the additional step of substantially coating or coating the surface of the fibre with a coupling agent for coupling said fibre to the resin.

According to another aspect of the invention, a process is provided for the removal of sizing agent from a surface of a reinforcing fibre, the process comprising the step of contacting the reinforcing fibre with a suitable solvent for a period of time sufficiently long to substantially remove or to remove the sizing agent from the said surface.

The process according to this aspect of the invention may include the further step of washing the reinforcing fibre. The process according to this aspect of the invention may additionally include a rinsing step. Furthermore, the process according to this aspect of the invention may include a drying step in which the reinforcing fibre is dried.

The process according to this aspect of the invention may conveniently be conducted using a solvent in the contacting and/or washing and/or rinsing steps that comprises a chemical compound that facilitates the dissolution, hydrolysation or chemical conversion of the sizing agent. Thus, a compound such as ammonia may be used, in conjunction with water, to facilitate the removal of the sizing agent from a glass reinforcing fibre.

The sizing agent may be EVA or PVA.

I. [R:\LIBXX\NicovN\Hodgson]DivisionalAUco mpleteSpeci2002octoberI I .doc:JFM In the event that the sizing agent is PVA, the solvent may be water or an aqueous medium. PVA is usually relatively susceptible to hydrolysis, especially at high pH or in very hot water. The pH of the water may be raised using ammonia or another suitable mildly alkaline compound. The use of strong alkalies should be avoided if the reinforcing fibre is made of glass, because of potential damage to the fibres.

Conveniently, the temperature of the water or the aqueous medium is within the range of 15'C to 100 0 C, preferably from about 20'C to about 80'C, more preferably from about 251C to about 60'C, or 80'C to 100 0 C, or 85*C to 100 0 C, or 90'C to 100 0 C, or to 1 00 0 C, or 98°C to 100 0

C.

Where the solvent is water, the period of time may be sufficiently long and the temperature of the water may be sufficiently high for the PVA to hydrolyse.

According to another aspect of the invention, there is provided a process for making a reinforcing fibre suitable for use in reinforcing a composite made of the fibre and a resin, said process including the step of substantially removing or removing any sizing agent previously applied to the surface of the reinforcing fibre.

The process may include the additional step of substantially coating or coating the surface of the fibre with a coupling agent for coupling said fibre to the resin. The coupling agent may conveniently be selected from the group consisting of a polymerisable coupling agent and a coupling agent which is at least partially polymerised.

Where the fibre is substantially inorganic or inorganic and the resin is substantially organic or organic, the coupling agent may comprise a plurality of molecules each having a first end which is adapted to bond to the fibre and a second end which is adapted to bond to the resin. The coupling agent may be a coupling agent which is at least partially polymerised. The coupling agent may be a polymerisable coupling agent.

According to another aspect of the invention, there is provided a reinforcing fibre, wherein said fibre has a surface which is substantially coated or is coated with a coupling agent for coupling said fibre with a resin when cured so as to improve impact resistance, tensile strength and flexural strength of a cured composite comprising said resin when cured, said coupling agent being selected from the group consisting of a polymerizable coupling agent and a polymerized coupling agent and 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002OctoberI I.doc:JFM said cured composite further comprising a plurality of said fibres coated with the polymerized coupling agent incorporated in said cured resin.

In one particular form of the invention, there is provided a reinforcing fibre, wherein said fibre has a surface which is substantially coated or is coated with a polymerized coupling agent for coupling said fibre with a resin when cured so as to improve impact resistance, tensile strength and flexural strength of a cured composite comprising said resin when cured and said polymerized coupling agent incorporated in said cured resin.

According to another embodiment of this invention there is provided a process for 1o making a reinforcing fibre, said process comprising: substantially coating or coating the surface of the fibre with a polymerizable coupling agent for coupling said fibre to a resin so as to improve impact resistance, tensile strength and flexural strength of a cured composite comprising the resin when cured, and polymerizing the polymerizable coupling agent.

Depending on the type of fibre and the type of coupling agent it may be necessary to pretreat the surface of the fibre to enable it to be coated with the coupling agent. For example, where the fibres comprise mica platelets such platelets are usually coated with a metal oxide coating iron oxide or other metal oxide) prior to coating with the polynierizable hydrophilic coupling agent.

The invention also extends to a reinforcing fibre made by the any one of the aforementioned processes, to a curable composite and to a cured composite comprising a reinforcing fibre according to the invention. The invention further extends to a curable composite and to a cured composite made by a process according to the invention for making a curable composite or a cured composite.

According to another embodiment of this invention there is provided a process for making a plurality of reinforcing fibres, said process comprising: mixing the plurality of fibres with a liquid comprising a polymerizable coupling agent for coupling said fibre to a resin so as to improve impact resistance, tensile strength and flexural strength of a cured composite comprising the resin when cured, and 1. [R:\LIBXXNicovN\Hodgson]DivisionalAUcompleteSpeci2002octoberI I.doc:JFM I polymerizing the polymerizable coupling agent in the liquid so as to substantially coat the surfaces of the plurality of fibres with polymerized coupling agent.

Depending on the type of fibre and the type of coupling agent it may be necessary to pretreat the surface of the fibre to enable it to be coated with the coupling agent. For example, where the fibres comprise mica platelets such platelets are usually coated with a metal oxide coating iron oxide or other metal oxide) prior to the mixing step.

The process may further comprise the step of separating the plurality of fibres from the liquid.

The process may further comprise the step of sieving the separated plurality of fibres.

According to a further embodiment of this invention there is provided a reinforcing fibre for a curable resin made by the process of the invention.

According to an additional embodiment of this invention there is provided a cured composite comprising a cured resin incorporating a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with or is coated with a coupling agent for coupling said fibre with the cured resin so as to improve impact resistance, tensile strength and flexural strength of said cured composite, said coupling agent comprising a polymerized coupling agent.

According to an additional embodiment of this invention there is provided a curable composite comprising a curable resin incorporating a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with or is coated with a coupling agent for coupling said fibre with the resin when cured so as to improve impact resistance, tensile strength and flexural strength of said composite when cured, said coupling agent comprising a polymerized coupling agent.

According to another embodiment of this invention, there is provided a process for making a cured composite comprising: preparing a curable composite by combining a curable resin and a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with or is coated with a coupling agent for coupling said fibre with the resin when cured so as to improve impact resistance, tensile 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002OctoberI I .doc:JFM

I

strength and flexural strength of a cured composite comprising the cured resin, said coupling agent comprising a polymerized coupling agent; and curing said curable composite.

According to another embodiment of this invention there is provided a method of applying a composite to a surface said method comprising: preparing a curable composite by combining a curable resin and a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with or is coated with a coupling agent for coupling said fibre with the cured resin so as to improve impact resistance, tensile strength and flexural strength of a cured composite comprising the cured resin, said coupling agent comprising a polymerized coupling agent; applying the curable composite to the surface; and curing said curable composite.

The step of applying can be by spraying, painting, pumping, brushing, wiping, streaking, pouring, rolling, spreading or other suitable applying methods used in fibreglass fabrication. By choosing fibres of mean length less than about 4mm the resin having said plurality of reinforcing fibres can be applied to the surface by spraying.

In the short fibre composite according to the invention, intimate bonding is desirable, so that applied stress fields in the composite may be dispersed via the matrix. Thus, in the composite according to the invention, the resin is preferably not too brittle and preferably has a relatively high elongation at break.

A composite which is the subject of this invention can utilize fibres the maximum mean length of which is in the range of about 0.25mm-7mm, 0.5-6.5mm, 1-6.5mm, 1- 6mm, 2-6mm or 2-5mm, or 2-4mm or 2-3mm, or 3-6mm or 3-5mm or 3-4mm more typically about 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 6mm or 6.5mm (the composite which is the subject of this invention can be pumpable and/or sprayed using current fibreglass deposition equipment a requirement that restricts mean fibre length to a maximum 4mm). A critical fibre length of the same order of magnitude was unacceptable for these particular applications. Thus for these applications it was of paramount importance to reduce the critical fibre length to under 1mm. This is achieved by improving coupling and reducing interfacial stresses 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci202octoberI I .doc:JFM by plasticising the interface by thoroughly coating the fibre with coupling agents such as silane coupling agents or suitable organo metal ligands, such as transition metal acrylates of significantly high molecular weight.

According to another embodiment of this invention there is provided a method of moulding a composite said method comprising: preparing a curable composite by combining a curable resin and a plurality of reinforcing fibres each of said reinforcing fibres having a surface which is substantially coated with or is coated with a coupling agent comprising a polymerized coupling agent for coupling said fibres with the cured resin so as to improve impact resistance, tensile strength and flexural strength of the composite when cured; locating the curable composite in a mould; and curing said curable composite in the mould.

The step of locating the curable composite in the mould may comprise pumping it, pouring it or otherwise placing it, in the mould. Where the moulding process involves injection moulding the step of locating the curable composite in the mould comprises injecting the curable composite into the mould.

This invention teaches the use of resins including flexible resins and resins with moderately high elongation at break to overcome the poor impact resistance improve tensile strength and flexural strength. The moderately high elongation at break brings more fibres into play when the composite is strained and distributes the strain, improving physical properties.

The coupling agent is preferably polymerized during and/or after the coupling process. It is desirable to have a preponderance of polymers adhering to the surface as the presence of these polymers effectively stress relieve the interface during curing of the composites. It is preferable to use short fibres for the preparation of composites because an uncured composite according to the invention that comprises short fibres and an uncured resin can be pumped and sprayed. Two or more different coupling agents may be used.

Preferably, the fibres do not have any sizing agent on their surfaces. In order to obtain such fibres from standard fibreglass fibres which come coated with sizing agents, it is desirable to remove such sizing agents from the fibres before coating the fibres with a 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002ctoberl 1 .doc:JFM

F

coupling agent. In addition, the density of coupling agents on the surface of the fibres is extremely high usually the polymerization of the coupling agent is performed to a substantial extent. For example, the step of polymerizing the coupling agent comprises polymerizing the coupling agent for a period in the range 1 60 hours, typically a period in the range 1- 10 hours, 10 30 hours, 12 30 hours, 15 hours, 15 30 hours or 20 30 hours. Typically the step ofpolymerizing the coupling agent comprises polymerizing the coupling agent for a period such as 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 hours.

According to another aspect of the invention, there is provided a cured glass fibre composite comprising a cured resin and a plurality of glass fibres, wherein the cured resin has an elongation at break, when measured in the absence of said glass fibres, of from about 4% to about 20% or about 5% to about 16% or about 5% to about The elongation at break of the resin is preferably about 5% to about 12%, more preferably from about 6% to about 10%. The elongation of break may be greater than Preferably, the glass fibres are reinforcing fibres that have been treated in accordance with the invention. Even more preferably, the glass fibres have surfaces that have been covered at least partially, but preferably completely, with a polymerizable coupling agent that has been at least partially polymerized in accordance with the invention.

Thixatropes such as fumed silica/inorganic thixatropes interfere with the resin bonding to fibres, by adding to interfacial stresses. Organic thixatropes especially the amide type such as Thixatrol Plus or hydrogenated castor oils or glyceryl stearate products help plasticize then interface and therefore improve bonding. These are preferred products when optimum strength of the composite is required.

Usually the entire external surface of a fibre is substantially coated with the coupling agent.

In the process of preparing the composite the fibres should be substantially individually wetted or individually wetted by the resin and substantially evenly distributed or evenly distributed throughout the resin. This is usually achieved by appropriately stirring the resin/fibre mixture at a sufficient rate of stirring to achieve this result. However, at the same time the stirring of the resin/fibre mixture should not be performed at such a high rate as to cause damage to the fibres.

i. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpecj2002October I .doc:JFM

P

In the process of preparing the composite it is desirable to use a polymeric thixotropic agent in the resin/fibre mixture particularly a polymeric amide thixatrope.

The resin used is one that has an elongation at break of 5-16%, 6-16%, 5-15%, 12%, 6-12%, 6-10%, more usually 5-10%, or even more usually The resin usually incorporates styrene as a diluent. The coupling agent is chosen such that it is capable of reacting with the styrene in the resin usually via a free radical mechanism.

The styrene forms a bond with the resin and thereby couples the coupling agent with the resin. Additionally, the coupling agent is chosen such that it is capable of coupling with the fibreglass. A 5% to 50% replacement of styrene with isobutyl methacrylate improves wetting of the resin and glass and improves the performance of the composite.

In one particular form the invention uses a plurality of ceramic fibres, more specifically glass fibres, and more specifically short glass fibre whose maximum average length is 4mm or 3.5mm or 3mm or less eg in the range 2mm to 4mm. Sizing if present on these fibres is removed. Depending on the nature of the sizing it may be removed by hydrolysis such as by boiling the fibres in water (this process leaves hydroxyl groups on the surface of the fibres). In other words a plurality of unsized short fibres are used. The plurality of unsized short fibres are coated with a silanecoupling agent which has a vinyl group attached, this vinyl group can enter into a free radical reaction. Care is taken while coupling to prevent polymerisation of the silanes in solution (initial concentration of solution is 0.50 a silanes in water). This may be done by keeping the coupling mixture, in which the unsized glass fibres and coupling agent are present, acidic, preferably at pH in the range of 3.2 to 3.7, more preferably about 3.5. The coupling is allowed to continue for at least one hour, usually in the range 1 -30 hours or 2-24 hours, 10-24 hours, 12-24 hours, 15-24 hours, 20-24 hours, and typically up to 24hrs. Once the fibres are coated with the silane coupling agent, the attached silanes coupling agents are polymerised with silanes in solution. This is achieved by raising the pH of the coupling mixture to a pH in the range of 7 to 10 or 7.2 to 9 or 7.2 to 8 or about pH 7.5. The silanol polymer is grown until the attached polymer represents approx 2% of the weight of the fibres. The coupling reaction and the polymerising reaction may be performed with stirring, usually constant stirring, so that all the fibres have an equal opportunity to be coated and the coating polymerised uniformly. The stirring during the polymerising may be in the range of 1- 1. [R:\LfBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci202OctberI I.doc:JFM hours or more, or may be about 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 hours or more.

Thereafter the mixture may be allowed to stand for a period of time in the range of 1- 36 hours or 1 -24 hours or 4 -24 hours or 6 to 18 hours or 6 to 12 hours to allow the fibres to settle prior to separating fibres and coupling solution. The resultant fibres now consist of silanols of high molecular weight bonded to the glass fibre. The fibres may be dried and sieved to break up agglomerates. The fibre may be added to vinyl functional resins with moderately high elongation at break elongation at break or higher, e.g. in the range of 5% to 20% or 5% to The fibres with the polymerised coupling agent coupled thereto are mixed into the resin carefully to minimise fibre breakage and air entrapment during the mixing process. The mixing process is performed carefully to avoid agglomerations of fibres and ideally "every" fibre is wetted individually. Thus in this form of the invention the use ofunsized short ceramic fibres, (preferably less than 4mm fibres), which fibres are coupled with coupling agent, and thereafter the coupling agents on the coupled fibres are polymerised with coupling agent in the coupling mixture to form a polymer coating on the fibre of high molecular weight. Such fibres with polymerized coupling agent thereon may be added to a suitable vinyl functional resin of moderately high elongation at break (e.g in the range of 5% to 15% or 5% to 12% or 5% to 115 or to 10%) to make a pumpable and/or sprayable, curable, liquid composite. This liquid composite may have a resin to fibre loading of less than two parts resin to one part fibre and still be fluid enough to spray using conventional resin spraying equipment.

This resin may obviate the need for the use of additional reinforcement (such as fibreglass mat). More particularly, the liquid composite when cured has enough physical strength in itself. For many applications it does not require extra reinforcement. This obviates the need for reinforcing rovings, reinforcing matting, reinforcing fabric's etc, vastly simplifying the fabrication process. In this form of the invention the type of fibre, the length of fibre, the treatment of the fibre, the resin of moderately high elongation at break, the mixing of the fibre into an appropriate amount of the curable resin (which may be a flexible, liquid, thermosetting resin) so that all the fibres are wetted and the resultant rheology of the liquid composite is such that it cart be pumped and/or sprayed. The composite may be one that cures at room temperature after addition of a suitable hardener.

Other aspects of this invention include: 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002ctober I.doc:JFM A reinforcing fibre having a surface with no sizing agent thereon, wherein the surface of the fibre is completely coated with a polymerised coupling agent for coupling said fibre with a resin when cured wherein the reinforcing fibre is inorganic and is suitable for use with a resin which is organic, the coupling agent comprising a plurality of molecules each having a first end adapted to bond to the fibre and a second end which is adapted to bond to the resin and said fibre has a maximum fibre length of 6 mm.

A process for making a plurality of reinforcing fibres for use in reinforcing a resin composite comprising said plurality of said reinforcing fibres and a cured resin, said process including the steps of: mixing a plurality of fibres with no sizing agent on the surfaces thereof with a solution comprising a polymerisable coupling agent so as to coat the surfaces of said fibres with the polymerisable coupling agent; and polymerising said polymerisable coupling agent.

A curable composite comprising a curable organic resin and a plurality of reinforcing fibres, each reinforcing fibre having a surface with no sizing agent thereon, wherein said surface of said reinforcing fibre is completely coated with a polymerised coupling agent and said fibre has a maximum fibre length of 6 mm.

A process of making a curable composite comprising: mixing a plurality of reinforcing fibres with no sizing agent on the surfaces thereof with a solution comprising a polymerisable coupling agent so as to coat the surfaces of said fibres with the polymerisable coupling agent; polymerising said polymerisable coupling agent; filtering the plurality of reinforcing fibres having the polymerised coupling agent; drying the filtered plurality of reinforcing fibres; sieving the dried plurality of reinforcing fibres to break up agglomerates; and suspending the dried, sieved plurality of reinforcing fibres in a curable organic resin.

A process of making a curable composite comprising: mixing a plurality of reinforcing fibres with no sizing agent on the surfaces thereof with a solution comprising a polymerisable coupling agent so as to coat the surfaces of said fibres with the polymerisable coupling agent, wherein the length of the fibre is selected from the group consisting of a maximum fibre length of 6 mm, a fibre length of less than 5 mm, a fibre length of less than about 4 mm, a fibre length of about 3 (R:\LIBXX]04164.doc:aak 16 mm, a fibre length of less than 2 mm, a maximum mean fibre length of 3 4 mm, a mean fibre length in the range of 0.5mm to lmm, a mean length of about 0.5mm, a fibre length distribution in the range of 6 mm to 1 mm, a fibre length of approximately 3 mm with less than 1% fibres greater than 4 mm, a fibre length distribution of less than 2% by wt fibres greater or equal to 4 mm, less than 4 mm and greater or equal to 2 mm between 5% and by wt fibres and less than 2 mm between 5% and 50% by wt fibres; polymerising said polymerisable coupling agent; filtering the plurality of reinforcing fibres having the polymerised coupling agent; drying the filtered plurality of reinforcing fibres; sieving the dried plurality of reinforcing fibres to break up agglomerates; and suspending the dried, sieved plurality of reinforcing fibres in a curable organic resin, wherein said resin is selected from the group consisting of epoxy vinyl ester resins, unsaturated polyester resins, vinyl ester resins, vinyl functional resins, tough vinyl functional urethane resins, tough vinyl functional acrylic resins, non plasticised flexible polyester resins and combinations thereof and said resin has an elongation at break, when cured, selected from the group consisting of greater than 6% and greater than A process of making a curable composite comprising: suspending, in a curable organic resin, a plurality of dried, sieved reinforcing fibres, each of said reinforcing fibres having a surface with no sizing agent thereon, wherein said surface of each of said reinforcing fibres is completely coated with a polymerised coupling agent and wherein each of said reinforcing fibres has a maximum fibre length of 6 mm.

A process of making a curable composite comprising: suspending, in a curable organic resin, a plurality of dried, sieved reinforcing fibres, each of said reinforcing fibres having a surface with no sizing agent thereon, wherein said surface of each of said reinforcing fibres is coated with a polymerised coupling agent, said reinforcing fibres being in an amount selected from the group consisting of from 10% to 60% by weight of said reinforcing fibres and from to 50% by weight of said reinforcing fibres, the length of said reinforcing fibres being selected from the group consisting of a maximum fibre length of 6 mm, a fibre length of less than 5 mm, a fibre length of less than about 4 mm, a fibre length of about 3 mm, a mean fibre length in the range of 0.5mm to 1mm, a fibre length of less than 2 mm, a maximum mean fibre length of 3 4 mm, a fibre length distribution in the range of 6 mm to 1 mm, a mean fibre length in the range of 0.5mm to lmm, a mean length of about [R:\LIBXX]04164.dc:aak a fibre length of approximately 3 mm with less than 1% of fibres greater than 4 mm, a fibre length distribution of less than 2% by wt fibres greater or equal to 4 mm, less than 4 mm and greater or equal to 2 mm between 5% and 50% by wt fibres and less than 2 mm between 5% and 50% by wt fibres; wherein said resin is selected from the group consisting of epoxy vinyl ester resins, unsaturated polyester resins, vinyl ester resins, vinyl functional resins, tough vinyl functional urethane resins, tough vinyl functional acrylic resins, non plasticised flexible polyester resins and combinations thereof and said resin has an elongation at break, when cured, selected from the group consisting of greater than 6% and greater than 0o A reinforcing fibre having a surface with no sizing agent thereon, wherein said fibre has a surface which is completely coated with a coupling agent for coupling said fibre with an organic resin when cured, said coupling agent being at least partially polymerised and said fibre has a maximum fibre length of 6 mm.

Is Throughout the specification and claims a reference to a resin is to be understood to be a reference to a resin per se (or)? Examples of Materials The following list is by way of exemplification only and is by no means an exhaustive list.

Monomers and Oligomers Mono and di and trifunctional acrylates and methacrylates, styrene, and polyallyl ethers.

GP UPE Laminating Resins Eterset 2504 PT orthophthalic ethylene glycol fumaric/maleic acid resin, Eterset 2597 PT orthophthalic ethylene glycol fumaric/maleic acid resin, and NAN YAR LA111 orthophthalic ethylene glycol fumaric/maleic acid resin.

Chemical Resistant UPE resins Eterset 2733 Ortho NPG fumaric/maleic acid chemical resistant resin, Eterset 2731 Iso NPG fumaric/maleic acid chemical resistant resin, NAN YAR GL316 Iso NPG fumaric acid chemical resistant resin, Swancor 901 45, Swancor 911 Hetron 922, and Derakane 411 Flexible Resins SYN6311 Cray Valley, F61404 30 NUPLEX, Swancor 980 Toughened VE Swancor 981 Flexible VE, and Aromatic Corp flexible VE.

Cure In Air UPE Resins ROSKYDAL 500A, and VUP4732 SOLUTIA.

[R:ALIBXX]04164.doc:aak

F

Toughening Additives SARTOMER CN962 URETHANE ACRYLATES, SARTOMER CN964 URETHANE ACRYLATES, SARTOMER CN965 URETHANE ACRYLATES and HYCAR REACTIVE LIQUID POLYMER 1300X33 VTBNX.

Plasticizers PALAMOL ADIPATES, and DI BUTYL PHTHALATE.

Cure In Air Additives SANTOLINK XI 100, PMMA, and PS Thixatropes Rheox THIXIN E, Rheox THIXATROL+, FUMED SILICAS Cabot, Wacker, and TREATED CLAYS.

Promoters COBALT OCTOATE, COBALT OXALATE, POTASSIUM OCTOATE, ZIRCONIUM OCTOATE, VANADIUM NAPHTHENATE, COPPER NAPHTHENATE, ZINC OCTOATE, and DMA.

Inhibitors ACETYL ACETONE, HYDROQUINONE, and TBHQ.

Air Release Agents BYK A515 AND 510, SWANCOR 1317, BEVALOID 6420 and Leveling Agent EFKA 777 Catalysts MEKP, CHP, and benzoyl peroxide Fibres Where reinforcing fibres are not coated with acid soluble materials such as iron oxides, the coupling agent may be mixed with the fibres at acidified pH about pH 3) and the pH may then be gradually raised over 10 36 hours to pH 7 1 pH unit.

1. [R:\LBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002Octoberl 1.doc:JFM Where the fibres are coated with acid soluble materials such as iron oxides, the coupling agent may be mixed with the fibres at neutral pH about pH 7) and the pH maintained or gradually raised over 10 36 hours to pH 9 1 pH unit.

Throughout this specification the terms fibre and fibres are to be taken to include platelet and platelets respectively. Surface treated mineral fibres such as Wollastonite, or mica and ceramic fibres such as glass fibres are the most suitable fibres for purposes of glass fibre composites. However, surface treated synthetic fibres may also be used surface treated aramid fibres, mylar fibres, nylon fibres, linear polyethylenes, linear polypropylenes, polyesters and carbon fibres). The maximum fibre length may be 6 mm, and the mean fibre length may be 4 mm or less.

Alternatively, surface treated platelets may be used, such as mica platelets, preferably precoated with a suitable metal oxide such as iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide, zirconium dioxide or the like.

Further examples of fibres are fibres made from Vetrotex, Camalyef, SUR100, or HPR800; Kevlar/aramid fibres; Wollastonite fibres; Nylon fibres; and calcined surface treated micas. Any of the aforementioned fibres may be milled to yield fibres of a suitable length.

In the case of glass fibre, it is preferable to use fibres made from E glass or S glass, E glass has a tensile strength of around 3.6 giga Newtons per square meter whilst S glass has a tensile strength of around 4.5 giga Newtons per square meter.

Fillers Zenospheres, PVC Powder, and treated organo clays.

Coupling Agents Silanes/acrylic functional, silanes/vinyl functional, silanes/styrene functional, silanes and transition metal acrylates and methacrylates such as zinc diacrylate.

Silanes having an acrylic functional group at one end of the molecule are preferred.

Silanes having a styrene functional group tend to be too reactive.

The advantages of this Technology over the current art are: 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002octoberI I .doc:JFM

I

Fewer people required to produce a part no laminators required.

Improved work place health and safety, fewer people exposed to styrene emission, lower styrene levels.

Much faster mold turnaround, increased productivity.

Improved chemical resistance.

Composite can be applied by robot.

The invention provides amongst other things a sprayable/pumpable reinforced resin composite that does not require mechanical consolidation. This composite can be used for fabricating FRP objects such as swimming pools, boats, baths, spas, liquid storage tanks, fibreglass panels, cowlings, etc. It can be used with foaming resins to add mechanical strength, and it is ideally suited to resin injection molding.

Best Mode And Other Modes For Carrying Out The Invention Modification of the Surface of Fibres and Methods of Forming Composites The standard surface treatment of fibres is not satisfactory. The silane coupling agents used are not applied thoroughly in the case of glass rovings. Commercially available milled glass rovings are manufactured from continuous rovings which have been coated with a sizing material such as EVA or PVA emulsion. This sizing must be removed from the milled glass prior to coating the fibre with coupling agent. And in the case of mineral fibres the coupling agents on commercially available fibres are too low in molecular weight and density on surface of the fibres.

In order to optimize the performance of the composites it is necessary to optimize the application of silanes to modify the chemistry and therefore the forces at the interface of the fibres with the resin. This may be achieved by partially polymerizing the silane coupling agents prior to bonding them to the fibres.

In one form this may be achieved by allowing the silanes in aqueous solution to polymerize at suitable pH (pH 7 or greater) for a suitable time, prior to acidification and coupling.

It is theorized that the reaction rate of the higher molecular weight silanes bonding to the fibres is considerably slower due to, among other influences, steric hindrance. For 1. [R:\LfI3XX\NicovN\Hodgson]Divisiona1AUcompeteSpeci2OO2octobe1 I .doc:JFM this reason fibres are left soaking in the aqueous silane for up to a day or longer to optimize the population of higher molecular weight silanes on the surface.

The aim is to improve bonding, and stress relieve the interface during polymerization of the resin matrix.

Reducing interfacial stress is critical to optimize the performance of the short fibre composite.

Alternatively (where the fibres are not coated with acid soluble materials such as iron oxides), the coupling agent may be mixed with the fibres at acidified pH about pH 3) and the pH gradually raised over 1 36 hours to pH 7 1 pH unit where they are allowed to stand for a period from 1 to 10 hrs or longer to allow the aqueous silanes to polymerize onto the coupled silanes. Where the fibres are coated with acid soluble materials such as iron oxides, the coupling agent may be mixed with the fibres at neutral pH about pH 7) and the pH maintained or gradually raised over 10 36 hours to pH 9 1 pH unit.

Throughout this specification the terms fibre and fibres are to be taken to include platelet and platelets respectively. Surface treated mineral fibres such as Wollastonite, and ceramic fibres such as glass fibres are the most suitable fibres for this invention however surface treated synthetic fibres can be used surface treated aramid fibres, mylar fibres, nylon fibres, linear polyethylenes, linear polypropylenes, polyesters and carbon fibres). Maximum fibre length 6mm, mean fibre length 4mm or less. Alternatively, surface treated platelets such mica platelets (if pre-coated with a suitable metal oxide such as iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide, zirconium dioxide etc).

Resins with an elongation to break of greater than 6% are preferred. The most suitable resins are those which are naturally tough and with an elongation at break greater than For lining of concrete vessels, and steel vessels to improve their chemical resistance, resins with low elongation at break are suitable.

However for load bearing structures the resins with higher elongation at break give best performance.

1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002Octoberl 1.doc:JFM As mentioned before the more "elastic" the resin is the stronger and more serviceable the composite.

As the of reinforcement increases so do the mechanical properties of the composite up to a point, and then the tensile strength of the laminate begins to fall.

Until better bonding is achieved between the resin and the reinforcement, fibre contents of around 30% to 50% by weight appear optimum.

The most suitable resins are epoxy vinyl ester resins, tough vinyl functional urethane resins, tough vinyl functional acrylic resins, and flexible polyester resins the non plasticized type.

Removal of sizing Agent from Reinforcing Fibres; Covering with Coupling Agent Commercially available milled glass rovings are manufactured from continuous rovings which have been coated with a sizing material such as EVA or PVA emulsion.

For the best mode, and so as to achieve improved bonding of a coupling agent to the reinforcing fibre, such sizing should preferably be completely removed from the reinforcing fibre prior to coating of the fibre with a coupling agent. Where the sizing agent is PVA, this should be done with hot, preferably boiling water, in order to minimize the time required for hydrolysation.

In order to further improve the performance of a composite, a polymerizable coupling agent should preferably be used to cover the fibres, preferably completely, after the sizing agent has been removed. Such coupling agent should preferably be at least partially polymerized before and/or after it has been applied to the reinforcing fibre before it is used with a resin to make a desired article or a structure.

In one mode, an aqueous silane solution is allowed to polymerize for a suitable time, which may be up to 24 hours, at a suitable pH, which may be a pH of 7 or greater, prior to acidification and coupling to a glass fibre.

Fibres are preferably soaked in an aqueous solution of a silane for up to a day or longer in order to facilitate the population of higher molecular weight silanes on the surface of the fibres.

1. [R:\LIBXX\NicovN\Hodgson]DivisionaIAUcompleteSpeci2OO2OctoberI I.doc:JFM

F

When using transition metal acrylates and methacrylates, it is best practice to add these to the liquid resin, rather than trying to couple them to the fibres prior to adding fibres to the resin. This is especially so when using aramid or polyamide fibres.

The present invention teaches that, where a coupling agent has been caused to polymerize so as to have a higher molecular weight than is conventionally used for the coupling of a reinforcing fibre, a composite having an improved impact resistance and/or an improved tensile strength and/or an improved flexural strength and/or an improved chemical resistance can be obtained.

Glass fibre compositions according to the invention, containing short fibres that have been treated by the process in accordance with the invention are preferably used for the manufacture of articles and structures that require strong composites.

Furthermore, a pumpable and/or sprayable composition that contains short fibres is preferably prepared for the manufacture of composite articles. Such compositions are preferably pumped and sprayed so that labour and time expended in the manufacture of such composite articles may be reduced.

Fibre to resin ratio It will be appreciated that various factors should be taken into account in deciding on what the fibre to resin ratio for a particular finished composite article or structure should be. These factors include the stresses to be applied to the article or structure when it is used, the chemical nature of the environment in which it will serve its function, the type of resin and the nature and length of fibres that are to be used in the composite. Thus, a wide range of resin to fibre ratio's can be used for composites according to the invention. In general, it could be stated that, as the ratio of reinforcement fibre to resin increases in a composite in accordance with the invention, so do the mechanical properties of the composite improve. However, beyond a certain point, the impact resistance and/or the tensile strength and/or the flexural strength of the laminate will begin to decrease. Following the teachings of this invention carefully, the best fibre to resin ratio for any particular situation as well as the upper limits of the fibre to resin ratio's for different resins and fibres can be determined by a person skilled in the art without the expenditure of undue effort.

Preparation of Laminates Laminate products such as swimming pools can advantageously be made by the following four methods ('hardener' in Methods 1 4 below may be a promoter and/or 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002october I.doc:JFM

F

initiator or other suitable hardener. The composite may also optionally include air release agent(s) and/or thixotrope(s) and/or other suitable additives): Method 1 Method I is the application of liquid composite only to a mould no external rovings, mats, sheets, etc of reinforcing are required.

A mould is wetted with a liquid composite resin of the invention (mixed with an appropriate hardener) using a conventional spray gun. The liquid composite resin contains approximately 15% or more by volume short fibres (eg in the range 15% 15% 45%, 15% 40%, 15% 35%, 15% 30%, 15% 25%, 15% 20% by volume or 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 30%, 45% or 50% by volume). In the event that a swimming pool, boat, or storage tank is built, it is preferable to apply no more resin than is required to obtain a resin to fibreglass ratio of about 2 to about 3:1. The glass fibres are pre-treated in accordance with the invention, by removing the sizing agent, if necessary, and by covering them with a polymerizable coupling agent which is subsequently allowed to polymerize.

The mould is sprayed with the composite resin/hardener, as required. A single layer or multiple layers of composite/hardener mixture may be applied to the mould 2, 3, 4, 5, 6, 7, 8, 9 or more). With the resin composites according to the invention being used, minimal or no mechanical consolidation for the removal of entrained air is required. For this reason, method 1 has the advantage that is less labour intensive than the prior art methods, because mechanical consolidation using rollers may be eliminated or greatly reduced using curable compositions in accordance with the invention.

Method 2 Method 2 allows for chopped rovings to be sprayed onto the mould with liquid composite containing approximately 15% or more by volume short fibres (eg in the range 15% 50%, 15% 45%, 15% 40%, 15% 35%, 15% 30%, 15% 25%, 20% by volume or 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 35%, 40%, 45% or 50% by volume) as described in method 1.

More particularly, a mould is wetted with a combination of a liquid composite/hardener and chopped fibres using a conventional fibreglass depositor, a chopper capable of chopping additional glass fibres and a resin fan (also referred to 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002octoberI I .doc:JFM i herein as a composite/hardener fan or a composite fan). The composite comprises a resin with short glass fibres may be mean length in the range 1.0 -6.5mm or 1.5 4mm) dispersed therein. One uses a resin with glass fibres dispersed in it, otherwise the strength of the composite will be reduced because the resin to glass ratio is increased if you spray extra resin to consolidate the laminate. The glass fibres in the liquid composite are pre-treated in accordance with the invention, by removing the sizing agent, if necessary, by hydrolysis, and by covering them with a polymerizable coupling agent which is subsequently polymerized.

This method differs from method 1 in that additional chopped glass fibre rovings are added to the composite as it is deposited onto the mould. This is done in order to provide improved strength to a product such as a swimming pool, particularly in areas such as the coping and where lifting lugs are to be fitted to the pool. The additional fibres are applied to the mould by operating the chopper causing chopped fibres to be sprayed into the composite/hardener fan. In this way, a resin to glass fibre ratio of about 2.5:1 to about 3.5:1 can be obtained.

When chopped fibres and resin composites according to the invention are used, minimal or no mechanical consolidation for the removal of entrained air is required.

This method thus involves the combination of a short fibre composite sprayed onto the mould with chopped rovings added into the composite fan.

For this method, the resin used in the composite is preferably a non air inhibited resin.

It preferably contains a moderate percentage of short fibres according to the invention. It may be either a hydrogenated unsaturated phthalic acid resin, a so called RIC acid resin, or it is an unsaturated polyester or vinyl ester resin containing dialyl ethers, or a soluble thermoplastic resin to produce a non air inhibited resin matrix.

Any air bubbles in the composite do not affect the chemical resistance of the cured composite. A number of layers are usually applied.

In method 2, a small percentage of glass is chopped into the composite/hardener fan, preferably at a (resin plus dispersed glass fibre) to maintain a resin to glass ratio in the range 2.5 to 4:1. To achieve this, the chopper motor may be slowed down, or alternatively the composite/hardener supply may be increased. What this means is that there is a lot more (resin plus dispersed glass fibre ie liquid composite) available for spraying to consolidate the laminate.

I. [R:\LIBX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002Octoberl I.doc:JFM When the resin composites according to the invention are used, minimal or no mechanical consolidation for the removal of entrained air is required. For this reason, method 2 also has the advantage that is less labour intensive than the prior art methods, because mechanical consolidation using rollers may be obviated or greatly reduced. Much less chopped rovings are required to achieve adequate strength in a composite when combined with the liquid short fibre composite instead of using straight laminating resin. In other words more "resin" ie short fibre liquid composite can be applied without adversely affecting the actual resin to glass ratio. The excess liquid composite that is available is used to consolidate the laminate. This laminate does not require further mechanical consolidation.

The glass dispersed in the liquid composite contributes to the resin to glass ratio.

Resin is applied at resin to glass ratios equal to or in excess of two weight fractions of resin to one weight fraction of reinforcing. If the resin contains a significant amount of glass then a lot more liquid composite can be applied to a fixed weight of glass reinforcement to achieve a specific resin to glass ratio.

Assume one was trying to produce a laminate say two parts resin to one part glass ie a resin to glass ratio of 2:1.

Let us assume that one was going to chop 10 kilos of reinforcement, then with resin containing no glass fibres one could only spray 20 litres any more and the resin to glass ratio would be greater than 2:1.

If instead of spraying straight resin one was to spray the liquid composite containing glass fibres of the invention one could spray more than 20 litres before the resin to glass ratio exceeds 2:1. If the amount of glass suspended in the liquid composite was in the ratio of one part suspended glass to two parts resin it would not be possible to make enough liquid composite to spray on the 10 kilos of reinforcement to achieve a resin to glass ratio of 2:1.

Two iterations are described below to demonstrate what happens if the liquid composite contains 15% or 20% fibreglass.

10 Kg of Glass Reinforcement 10 Kg of Glass Reinforcement 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci202OctoberI I .doc:JFM consolidated with liquid composite consolidated with liquid composite containing 15% glass (R/G 2:1) containing 20% glass (R/G 3:1) First iteration gives an extra 3kgs of glass 6 Add an extra 6 Kg liquid composite 18 This provides an extra 0.9 Kg of glass 3.6 Add an extra 1.8Kg of liquid composite 10.8 This provides an extra 0.27 Kg of glass 2.2 Therefore an extra 0.5kg of liquid composite is needed 6.6 For the 15% liquid composite an extra 8Kg of liquid composite was required to maintain a resin to glass ratio of 2:1 For the 20% liquid composite an extra 35.4kg of liquid composite was required to produce a laminate with a resin to glass ratio of 3:1.

The energy available in the spray fan to spray the extra liquid composite is sufficient to consolidate the laminate.

No other mechanical consolidation is required, the energy for consolidation is supplied by the spray systems resin pump. If the resin contains 5% iso butyl methacrylate then optimum glass wetting is achieved. The mechanical energy in the extra liquid composite is used to consolidate the laminate. Non air inhibited resins are used if the part is going to be immersed in water or aqueous solutions.

Method 3: The surface of a mould is wetted with a combination of a liquid composite of the invention /hardener using a conventional fiberglass depositor. A glass fibre fabric is laid on the surface of the liquid composite and then wetted with a composite of the invention (together with hardener) The composite of the invention comprises a resin containing short glass fibres dispersed in it. The liquid composite contains or or or or9%, or 10% by weight isobutyl methacrylate monomer to facilitate wetting of the glass matting.

1. [R:\LIBXX\NicovN\Hodgson]DivisionaiAUcompleteSpeci2OO2October I .doc:JFM The fabric is hosed with the composite/hardener, as required, with the composite/hardener sprayed on to the fibreglass fabric. A single layer or a number of layers of composite/hardener may be applied 2, 3, 4, 5, 6, 7, 8, 9 or more).

When the resin composites according to the invention are used, minimal or no mechanical consolidation for the removal of entrained air is required. For this reason, method :3 has the advantage that is less labour intensive than the prior art methods, because mechanical consolidation using rollers may be eliminated or greatly reduced using curable compositions in accordance with the invention which facilitate the wetting of a fabric without increasing the resin to fibreglass ratio unduly or at all.

Method 3 laminates have higher flexural modulus than do similar composites made with standard laminating resins. They also exhibit higher tensile strength and higher flexural strength over conventional lay-ups.

For this method, the resin is preferably a non air inhibited resin. It preferably contains a moderate percentage of short fibres according to the invention. It is either a hydrogenated unsaturated phthalic acid resin, a so called RIC acid resin, or it is an unsaturated polyester or vinyl ester resin containing dialyl ethers, or a soluble thermoplastic resin to produce a non air inhibited resin matrix. A number of layers may be laid down on the mould. Any air bubbles in the resultant laminate do not affect the chemical resistance of the cured laminate.

Formulation Space As used in this specification, the term formulation space means a set of all the preferred combinations of the components of the formulation that will produce a composite in accordance with the invention. There is no stoichiometry in unsaturated resin formulating. Components may be infinitely varied within the limits stated hereinafter. A formulation space is thus a multi dimensional space that includes all preferred formulations.

As an example, a long gel time or a short gel time may be required.

As another example, a high exotherm or a low exotherm may be required.

As a further example, zero shrinkage resin may be required.

As yet another example, a tough resin may be required.

Alternatively, one may require an elastomeric resin.

1. [R:\LIBXX\NicovN\ Iodgson]DivisionalAUcompleteSpeci2002October I .doc:JFM As a further alternative, one may need optimum physical properties.

As a further alternative, one may require excellent chemical resistance.

Furthermore, combinations of the above may be required.

NOTE For all formulations bellow 5 to 30% of styrene monomer can be replaced by isobutyl methacrylate and or 5 to 30% replacement of styrene with methyl methacrylate monomer to aid in fibre wetting and air release.

Formulation Space for Method 1 Resin solution in styrene Reactive monomers and or oligomers Fibres coated with or oxide coated platelets coated with Coupling Agents Silanes, and or Organo- Metal Compounds Promotors/Catalysts by Weight 20% to 89.999% 0% to 10% to 0.001% to 10% active ingredient 0% to 0% to 0% to Thixotropic Agents Pigments UV Stabilizers Formulation Space for Method 1 by Weight Reactive Diluents (Vinyl functional monomers and oligomers, 20% to 89.999% Non Reactive Diluents (such as xylene or toluene) 0% to Fibres coated with or oxide coated platelets coated with Coupling Agents Silanes, and or Organo- Metal Compounds 10% to Promotors/Catalysts 0.001% to 10% active 1. [R:\LIBXX\NicovN\Hodgson]DivisionaIAUcompleteSpeci2OO2octoberI I.doc:JFM

I

Thixotropic Agents Pigments ingredient 0% to 0% to 0% to UV Stabilizers Formulation Space for Method 1 by Weight Resin Reactive Diluents (Vinyl functional monomers oligomers) 20% to 89.999% Non Reactive Diluents such as toluene or xylene or low molecular weight liquid aliphatic solvents Fibres coated with or oxide coated platelets coated with Coupling Agents Silanes, and or Organo- 0% to Metal Compounds Promotors/Catalysts 10% to 0.001% to 10% active Thixotropic Agents ingredient 0% to 0% to 0% to Pigments UV Stabilizers These formulations can be sprayed using conventional Example Glasscraft, Venus Gussemer, Binks Sames, etc.

fibreglass depositors. For One typical process for coating glass and/or wollastonite fibres comprises: Coupling solution: to water add 0.1-lwt%silane coupling agent, adjust pH to pH 3 typically using acetic acid or equivalent, add 50 parts by weight of uncoated/unsized glass fibres and/or wollastonite fibres, agitate slowly just to suspend fibres, allow to couple for approximately one hour. Adjust the pH to pH7.5 and add 0.1% silane coupling agent to the solution every 4 hours. Add additional 0.1% 5 times. This takes 29hrs. Filter fibres, then dry to >0.1wt% at about 1 10C. Sieve dried, coated fibres through 800gm 200ptm screen. Avoid agglomeration of fibres prior to adding to i. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2OO2Octobe1 I.doc:JFM resin. Incorporate fibres into resin gradually to optimise wetting of individual fibres and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite, when cured, has improved impact strength as compared to fibre composites where the fibres have not been treated as described above.

Another typical process for coating unsized glass and/or wollastonite fibres comprises: Coupling solution: to water add 0.1-lwt%silane coupling agent, adjust (if necessary) pH to pH 7 1 pH unit to allow partial polymerisation of coupling agent and then adjust to pH 3 typically using acetic acid or equivalent, add 50 parts by weight of uncoated glass fibres and/or wollastonite fibres, agitate slowly just to suspend fibres for 4hrs. Raise the pH to pH 7.5 stir for 4hrs. add 0.2% silane solution and stir slowly for 4hrs. Then filter fibres, and dry at 110 0 C. Sieve dried, coated fibres through 800tm 200pm screen. Avoid agglomeration of fibres prior to adding to resin.

Incorporate fibres into resin gradually to optimise wetting of individual fibres and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite has improved impact strength as compared to fibre composites where the fibres have not been treated as described above.

A further process for coating unsized glass and/or wollastonite fibres comprises: Coupling solution: to water add 0.1-lwt%silane coupling agent, adjust (if necessary) pH to pH 7 1 pH unit to start polymerisation of coupling agent, add 50 parts by weight of uncoated glass fibres and/or wollastonite fibres, agitate slowly just to suspend fibres stir slowly for about 24 hours, every four hours added 0.1% silane coupling agent to solution. When coupling and polymerizing is complete filter fibres, and dry to >0.1wt% at about 110°C. Sieve dried, coated fibres through 800gm 200[tm screen. Avoid agglomeration of fibres prior to adding to resin. Incorporate fibres into resin gradually to optimise wetting of individual fibres and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite has improved impact strength as compared to fibre composites where the fibres have not been treated as described above.

i. [R:\LIBXX\NicovN\Hodgson]Divisiona1AUcompleteSpeci2OO2october I .doc:JFM One typical process for coating mica platelets (5microns to 4000microns) comprises: Precipitate iron hydroxide from an iron (III) containing solution (eg 0.01-1M ferric chloride) by adjusting the pH to about pH 9 onto mica platelets. Filter platelets an dry at 400 0

C.

Coupling solution: to water add 0.1-lwt% silane coupling agent, adjust pH to pH 7, add 50 parts by weight of Fe 2

O

3 coated mica platelets, agitate slowly just to suspend platelets. Slowly agitate platelets in solution for 4hrs., add 0.2% coupling agent and stir for 4hrs, then filter platelets, then dry to >0.1wt% at about 110 0 C. Sieve dried, coated platelets through suitable aperture screen to break up agglomerates. Avoid agglomeration of platelets prior to adding to resin. Incorporate platelets into resin gradually to optimize wetting of individual platelets and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite has improved impact strength as compared to platelet composites where the platelets have not been treated as described above.

Another typical process for coating mica platelets comprises: Precipitate iron hydroxide from an iron (III) containing solution (eg 0.01-1M ferric chloride) by adjusting the pH to about pH 9 onto mica platelets. Filter platelets and dry at 400-600 0 C. Allow to cool then mill to mean particle size in the range 3mm ltm and then sieve. Coupling solution: to water add 0.1-lwt%silane coupling agent, adjust (if necessary) pH to pH 7 1 pH unit to allow partial polymerisation of coupling agent, add 50 parts by weight of calcined mica platelets, agitate slowly just to suspend platelets, slowly for 24 hours, then filter platelets, then dry to >0.1wt% moisture at about 110°C. Sieve dried, coated platelets through suitable screen to break up agglomerates. Avoid agglomeration of platelets prior to adding to resin.

Incorporate platelets into resin gradually to optimise wetting of individual platelets and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant 1. [R:\LIBXX\NicovN\Hodgson]DivsionaAUcompleteSpeci202OctoberI I .doc:JFM i composite has improved impact strength as compared to composites where the platelets have not been treated as described above.

A further process for coating process for coating mica platelets comprises: Precipitate iron hydroxide from an (III) containing solution (eg 0.01-1M ferric chloride) by adjusting the pH to about pH 9 onto mica platelets. Filter platelets and dry at 400 0 C-600 0 C. Coupling solution: to water add 0.1-lwt%silane coupling agent, adjust pHI to pH 7 to start polymerisation of coupling agent, add 50 parts by weight of calcined mica platelets, agitate slowly just to suspend platelets stir slowly for about 48 hours, then filter platelets, and dry to >0.1wt% at about 110 0 C. Sieve dried, coated platelets through 800im 200 jm screen. Avoid agglomeration of platelets prior to adding to resin. Incorporate platelets into resin gradually to optimise wetting of individual platelets and so as to avoid clumping in the resin. Add promoter and initiator and optionally air release agent(s) and thixotrope(s) and allow a composite to form. The resultant composite has improved impact strength as compared to composites where the platelets have not been treated as described above.

Fibre Length Specification Fibre length maximum 6 mm, typically less than 2mm. Fibre length distribution in the range 6 mm to 1mm.

Fibre Length Distribution Space Wt% 4mm 0% to <4mm, >=2mm 0% to <2mm, >=lmm 0% to <lmm 0% to 100% A typical fibre length space for swimming pools or liquid storage tanks >=4mm Less than 2% by Wt fibres <4mm but >=2mm Between 5% and 50% by Wt fibres <2mm Between 5% and 50% by Wt fibres Typical Tensile Strength of Method 1 laminates 60 to 100MPa I. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002OctoberI I.doc:JFM Typical Flexural Strength 80 to 150Mpa Method 2 Applying a laminate that contains chopped rovings but does not require mechanical consolidation.

Method 2 relies on a resin being non air inhibited for applications where the composite part will be exposed to water vapour at dew point or where composite will be immersed in water for long periods. This can be achieved in two ways. By incorporating a suitable thermoplastic polymer at approximately 0.3% to 1% by weight of total vinyl functional constituents. Or by adding suitable allyl crosslinkers that stop air inhibition. These are added at concentrations between 4% and 35% of total vinyl functional constituents.

Method 2 allows for fibres to be sprayed onto the mould with the non air inhibited resin and chopped rovings in the normal way. The resin contains approximately by volume short fibres to form a liquid composite of the invention described in method 1. Much less chopped rovings are required to achieve adequate strength when combined with the short fibre composite.

This allows for apparent "resin to glass" ratios greater than 3 to 1. The excess liquid short fibre composite available is used to hose down "furries" that is chopped rovings protruding from the wet laminate and to consolidate the laminate.

This laminate does not require mechanical consolidation and is potentially stronger than the Method 1 Laminate.

Deposition is preferably as follows: 1. Spray a bed with the liquid composite (includes promoter and/or initiator and optionally air release agent(s) and/or thixotrope(s)) about 0.1mm to 0.3mm deep.

2. Then spray liquid composite and chopped rovings together thinly, leaving about 5% to 10% of the first layer visible 3. Spray the "dry" rovings with liquid composite until completely wetted.

4. Spray rovings and liquid composite as in 2.0 then spray "dry" rovings as in 3.

Repeat step 4. until the required thickness is achieved.

6. Allow to cure and demold if necessary.

Please note that this procedure does not require mechanical consolidation.

1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002Octoberl I.doc:JFM If the laminate needs to be chemically resistant then step one above can be repeated until 1.5 two 2.5mm of liquid composite is deposited prior to building up the laminate. Also if the laminate needs to be chemically resistant then up to 30% of monomer in the liquid composite can be replaced by isobutyl methacrylate.

In Method 2 the resin in the liquid composite can be a standard laminating resin as the average composite fibre length is much greater than 4mm.

Typical Tensile Strength of Method 2 laminates >100MPa Typical Flexural Strength >150MPa Composite/Laminate Thickness Any thickness of composite can be achieved simply by applying multiple passes. It is best to use a build between 0.5mm and 1.0mm per pass, this minimizes air entrapment.

EXAMPLES

Example 1: Laboratory test laminates were sprayed using a Binks Sames pressure pot.

A Binks hand-piece internal catalyst mixer and a Robinson catalyst system were used.

Operating pressure: 80psi air nebulised.

Mould type used: waxed melamine board.

Small spa mould.

Test sample mold A small two person spa was made using a Robinson depositor and the resin formulated below.

The coping was reinforced with the Method 2 laminate. The product was successfully demolded. It was able to hold a full volume of water unsupported.

Sprayed and test molded panels have been tested to required ASTM test methods for Tensile Strength, Tensile Modulus, Flexural Strength, and Flexural Modulus.

Typical results for Method 1 laminates are Flexural Strength 80MPa to 160MPa 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002Octoberl 1.doc:JFM Flexural Modulus 3.5Gpa to 6Gpa Tensile Strength 60Mpa to 11OMpa Tensile Modulus 4.5GPa to 6GPa.

Typical composite Swancor 981 flexible Vinyl Ester resin 100parts Styrene Thixatrol amide thixatrope 3parts Cobalt octoate 6% solution Di methyl analine 0.15parts Wollastonite fibres treated in accordance with the invention 38parts Air release agent Swancor 1317 0.7parts Summary of test results: Impact resistance, tensile strength and flexural strength of composites Composition of Composites: Method 2 Composites Fibres used: Surface treated Wollastonite or milled glass fibres Coupling agent: 10% based on the weight of the glass fibres.

A resin to chopped rovings ratio (equivalent to resin to glass ratio) of 3,5:1 was used.

The resin used in each case is indicated below.

Impact tests 1. Swancor 980 toughened VE resin 25 kgcm/cm2 Charpy ASTM D256 2. Swancor 981 flexibleVE resin 22 kgcm/cm2 Charpy ASTM D256 3. F61404/30 Nuplex Flexible UPE resin 19 kgcm/cm2 Charpy ASTM D256 4. 2504 Eterset GP laminating resin 8 kgcm/cm2 Charpy ASTM D256 Tensile test ASTM D638M 1. Swancor 980 toughened VE resin 158 MPa 2. 2. Swancor 981 flexibleVE resin 134 MPa 3. F61404130 Nuplex Flexible UPE resin 65 MPa 4. 2504 Eterset GP laminating resin 109 MPa Test Results for Method 1 Composites Liquid Composite 35%W.V. Silane treated fibres Impact Tests 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002Octoberl I.doc:JFM 1. Swancor 980 toughened VE resin 22 kgcm/cm2 Charpy ASTM D256 2. Swancor 981 flexibleVE resin 21 kgcm/cm2 Charpy ASTM D256 3. F61404/30 Nuplex Flexible UPE resin 22 kgcm/cm2 Charpy ASTM D256 4. 2504 Eterset GP laminating resin 5 kgcm/cm2 Charpy ASTM D256 Tensile Strength Tests ASTM D638M W.V. Silane acrylic coated fibres, LA11 Nan Yar GP laminating resin: 60 MPa Swancor 981: 88 Mpa F61404 Nuplex flexible UPE: 45 Mpa (Necking resin too elastic) Swancor 980: 93 Mpa Flexural Strength (ASTM D790M) Silane styrene functional coated fibres Swancor 980: 152 Mpa F61404/30: indeterminate (too flexible) Example 2: Removal of Sizing Agent The following three experiments were done to compare the strength and the fracture morphology of composites made from glass fibre, so as to demonstrate the effect of the removal of the sizing agent from the reinforcing fibre prior to covering the surface of the glass fibres with coupling agent: Experiment 1: milled glass as supplied, bonded with resin; Experiment 2: milled glass as supplied placed in a 1% solution, in water, of coupling agent Z6030 acrylic functional organosilane for thirty hours at 25 0 C, and thereafter bonded with resin; and Experiment 3: milled glass washed to remove sizing, coupled with Z6030 coupling agent as in experiment 2 and then bonded with a resin.

Procedure A sample of 3/16" milled rovings was taken from a bag supplied by Owen Coming. It was divided into three sub samples.

Sample 1 was dried to constant weight at 105 0 C and used for Experiment 1.

Sample 2 was placed into a large vessel containing a 1% solution of Z6030 coupling agent in water for 30 hrs. The pH of the solution was buffered at pH3 using acetic acid. Sample 2 was then separated from the solution and dried to constant weight at 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002October I .doc:JFM

I

105 0 C. This sample was used for Experiment 2.

Sample 3 was placed into a vessel of boiling water for 20 minutes to hydrolyse sizing.

It was then rinsed in hot water and thereafter placed into a 1% solution of Z6030 coupling agent in water for 30 hrs. The pH of the solution was buffered at pH3 using acetic acid. Sample 3 was then separated from the solution and dried to constant weight at 105 0 C. This sample was used for Experiment 3.

Three composite panels were made, one from each of the three samples of rovings.

The panels were test specimens cast in a mould approximately 13 mm wide by 4 mm thick by 100 mm long. Flexibilised VE resin was used in a ratio to glass fibre of 2.3:1.

These experiments were carried out with both an unsaturated isophthalic acid resin and an orthophthalic acid resin.

The composite panels were then loaded in flexure. The configuration was a simply supported beam loaded at mid span.

The load was applied as a constant stress of 15 Newtons, once every minute, until failure.

Results The Ultimate Flexural Stress for Sample 1 (the untreated glass) was 75 Mpa.

The Ultimate Flexural Stress for Sample 2 (coupled but unwashed) was 72 Mpa.

The Ultimate Flexural Stress for Sample 3 (washed and coupled) was 137 Mpa.

The fracture morphology for Samples 1 and 2 was identical. A plethora of glass fibres of approximately 1.5mm average length protruded from both fractured surfaces. There was no evidence of a complex fracture surface when the fractured surfaces of Samples 1 and 2 were examined. The fracture morphology for Sample 3 showed very few protruding fibres. The average length of these fibres was less than 0.1 mm. The fractured surfaces exhibited a complex fracture morphology.

Conclusion The washing step, as applied to Sample 3, resulted in an improvement in the performance of the short fibre composite.

Example 3: Coupling Siloxanes were dissolved in water in a tank. The pH of the water was buffered at pH 3 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci202OctoberI I .doc:JFM i to pH 3,5 using acetic acid. The concentration of the siloxanes in the water was 0.5 to parts per hundred.

Chopped glass fibres, each having a length of 0.5 to 4mm, and from which all sizing agent had been removed, were added to the water in the tank by sieving them so as to prevent lump formation. The tank was constantly agitated to keep the glass fibres in suspension. If they were allowed to settle on the bottom of the tank for short periods, they tended to agglomerate. It was also important to not stir excessively, because the fibres could break.

After an hour of reaction, the pH of the solution was slowly increased to pH 7.5 over a period of several hours. The solution, with the fibres suspended therein, was then left stirring for a further period of about 20 hours to polymerize the attached siloxanes with the excess siloxanes in solution.

When the polymerisation process was complete, each individual glass fibre in suspension was substantially covered with polymerized siloxanes.

The fibres were then separated from the aqueous solution and dried to constant weight at 105'C. They were then sieved to break up any agglomerates and packed off.

Example 4: Dispersing Fibres in Resin The dried and sieved fibres of Example 3 were used to prepare a liquid fibreglass composite by mixing them with a polyester resin that had an elongation at break, when cured, of 5 In preparing the liquid fibreglass composite, it was endeavoured to achieve the following three objectives: 1. To wet all the fibres individually; 2. To cause minimum fibre breakage in doing so; and 3. To cause minimum inclusion of entrapped air in the liquid composite, by mixing in such a manner as to cause minimum turbulence.

The liquid fibreglass composite made in this way was found to be suitable for being pumped and for being sprayed on a mould. Test samples of the liquid fibreglass composite were cured and the cured samples were tested for strength. The cured samples were found to be at least 20 to 30% stronger than samples of cured composites made in the conventional manner.

1. [R:\LLBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002OtoberI I .doc:JFM Example 5: Experiment to quantify the difference between coupled fibres and fibres with polymerized coupling agents One of the theories behind optimizing the strength of short fibre composites is that it is essential to polymerize the coupling agent on the fibres. The attached siloxane polymer acts as a reactive plasticizer greatly reducing interfacial stress.

In this test, glass fibres were thoroughly coupled but were not polymerized.

Preparation of Fibres 800g of 3/16" hammer milled and washed Owen Coming glass fibres were placed in a 4 litre plastic beaker.

Three litres of water were then added to the beaker. Then 10ml of glacial acetic acid was added. This produced a solution of pH 3.0. After this 15 mills of DOW Coming Z6030 silane coupling agent was added.

The solution/suspension was then stirred for 3hrs.

The liquid fraction was then poured off and the glass fibres washed and dried.

The fibres were then suspended in Swancor 981 flexible VE resin at a resin to glass ratio of 2.5 :1 The composite was then cured and flexure test specimens were cast.

These were allowed to cure for 24Hrs at ambient temp and then post cured at 60C for 4hrs.

These panels were then tested for their flexural strength.

Results These test panels gave flexural strengths varying from 73MPa up to a maximum of The Average result was 77MPa. This must be compared with similar washed coupled and then polymerized coupled fibres which gave a minimum flexural strength of and a maximum flexural strength of 130Mpa, with an average flexural strength of 103Mpa (see Example 4).

1. [R:\LIBXX\NicovN\Hodgson]Divisiona1AUcompleteSpeci2OO2OctoberI I.doc:JFM

I

Conclusion It is clear that polymerizing the attached/bonded coupling agent dramatically improves the strength of a short fibre composite.

Disclosed herein is a product including a reinforcing fibre, a process for making a reinforcing fibre, a process for making a plurality of reinforcing fibres, a reinforcing fibre for a curable resin made by the process of the invention, a cured composite, a curable composite, a process for making a cured composite, a method of applying a composite to a surface, and a method of moulding a composite. The uniqueness of this invention has to do with the manufacture and nature of the fibre reinforcement, the nature of the resins used, the way in which the fibres are mixed into the resin and processes for applying the composite to a mould. The composite formed as a result of adding the short fibre reinforcement improves the impact resistance, the tensile strength, flexural strength of the cured composite, substantially simplifies the moulding process, increasing productivity and reducing or eliminating VOCs in the fabrication shop.

The product may be able to be sprayed onto a mould or injected into a mould.

The product when sprayed onto an open mould does not require mechanical consolidation or when injected into a closed mould does not require any additional fibre reinfbrcement.

The product when sprayed onto an open mould does not require mechanical consolidation to optimise the properties of the composite.

Also disclosed is a method for preparing the above product in which the reinforcing fibre is milled so that the mean fibre length is less than 5mm. Any sizing is removed friom these fibres These fibres are then treated with a coupling agent, dissolved in a suitable solvent. The fibres are agitated in suspension in the coupling agent solution for a period of hours so that the entire surface of the fibres are coated in the coupling agent, and the attached coupling agent is polymerised with coupling agent in solution.

The fibres are then filtered and dried. They are then sieved to break up agglomerates.

The dried sieved fibres are then added to a liquid resin so that all the fibres are wetted 1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002OctoberI I.doc:JFM

I

individually, without incorporating air. The liquid resin is formulated so that it can react chemically with the coupling agent on the fibres.

This product is then catalysed, applied to a mould and allowed to cure. In the above method the reinforcing fibres may be glass fibres, which are free of all surface pre treatment. These fibres are preferably milled so that they have a mean fibre length of approximately 2 to 3mm with less than 1% fibres greater than 4mm. An organo functional silane is then dissolved in water at pH of 3 and at a concentration of less than The preferred organo functional silanes are those that contain a carbon carbon double bond in their structure. The fibres are then added to the solution and agitated in suspension for a period of hours so that all the available surface of the fibre is coated with the silane. Optionally the pH can be raised after this period to between pH 7 and pH 10 so that the remaining silane molecules in solution will react with the bound silanes to produce silanol oligomers. The fibres are then filtered from solution and dried. They are then sieved to break up agglomerates and suspended in suitable liquid resins such as unsaturated polyester resins, vinyl ester resins, acrylic resins, vinyl functional resins and combinations. The liquid resin is formulated so that it can react chemically with the coupling agent on the fibres.

This product is then applied to a mould and allowed to cure.

Alternatively in the above method the fibre is milled mica which has been coated with calcined iron oxide prior to the application of silane coupling agents.

In the above method the fibres may be synthetic fibres such as nylons, aramid fibres, PET fibres, polyester fibres, surface treated linear polyethylene fibres. The coupling agent in these cases is a metal acrylate capable of forming chemical bonds to the surface of the fibres. An example is zinc diacrylate.

The polymerisable resin may be a resin with an elongation at break greater than These are the preferred resins because they produce products with superior physical properties.

1. [R:\LIBXX\NicovN\Hodgson]DivisionalAUcompleteSpeci2002Octoberl 1.doc:JFM

Claims (68)

1. A reinforcing fibre having a surface with no sizing agent thereon, wherein said surface of said reinforcing fibre is completely coated with a polymerised coupling agent and said fibre has a maximum fibre length of 6 mm.

2. A reinforcing fibre as claimed in claim 1, wherein said coupling agent had been partially polymerised prior to said coupling agent having been bonded to said reinforcing fibre.

3. A reinforcing fibre as claimed in claim 1 or 2, wherein said coupling agent has been selected from the group consisting of silanes/acrylic functional, silanes/vinyl functional, silanes/styrene functional, organo functional silanes including organo functional silanes containing a carbon carbon double bond, transition metal acrylates, organic metal ligands and zinc diacrylate.

4. A reinforcing fibre as claimed in claim 1 or 2, wherein said coupling agent is an organo functional silane coupling agent.

5. A reinforcing fibre as claimed in any one of claims 1 to 4, wherein the surface of said reinforcing fibre has been pre-treated with a metal oxide before application of the coupling agent thereto.

6. A plurality of reinforcing fibres wherein each of said fibres is as claimed in any one of claims 1 to 5, wherein the length of the fibres is selected from the group consisting of a fibre length of less than 5 mm, a fibre length of less than about 4 mm, a fibre length of about 3 mm, a fibre length of less than 2 mm, a maximum mean fibre length of 3 4 mm, a fibre length distribution in the range of 6 mm to 1 mm, a fibre length of approximately 3 mm with less than 1% fibres greater than 4 mm, a fibre length distribution of less than 2% by wt fibres greater or equal to 4 mm, a mean fibre length in the range of 0.5mm to 1mm, a mean length of about less than 4 mm and greater or equal to 2 mm between 5% and 50% by wt fibres and less than 2 mm between 5% and 50% by wt fibres.

7. A process for making a plurality of reinforcing fibres for use in reinforcing a resin composite comprising said plurality of said reinforcing fibres and a cured resin, said process including the steps of: fI:\DAYLIB\LIBXX\NicovN\Hodgson]ADiv2cIai2s0OAprilIOnadoc:JFM 44 mixing a plurality of fibres with no sizing agent on the surfaces thereof with a solution comprising a polymerisable coupling agent so as to coat the surfaces of said fibres with the polymerisable coupling agent; and polymerising said polymerisable coupling agent.

8. A process for making a reinforcing fibre as claimed in claim 7, including the step of: partially polymerising the polymerisable coupling agent prior to said mixing.

9. A process for making a reinforcing fibre as claimed in claim 7 or 8, wherein the coupling agent has been selected from the group consisting of silanes/acrylic functional, silanes/vinyl functional, silanes/styrene functional, organo functional silanes including organo functional silanes containing a carbon carbon double bond, transition metal acrylates, organic metal ligands and zinc diacrylate. A process for making a reinforcing fibre as claimed in claim 7 or 8, wherein said coupling agent is an organo functional silane coupling agent.

11. A process for making a reinforcing fibre as claimed in any one of claims 7 to wherein the coupling agent is a silane/vinyl functional, and said mixing step is at acidified pH.

12. A process for making a reinforcing fibre as claimed in claim 11, wherein said polymerising step is at a pH selected from the group consisting of 7 or greater and between 7 and

13. A process for making a reinforcing fibre as claimed in any one of claims 7 to 12, comprising pre-treating the surface of the fibre with a metal oxide.

14. A process for making a reinforcing fibre as claimed in any one of claims 7 to 13, wherein the length of the fibre is selected from the group consisting of a maximum fibre length of 6 mm, a fibre length of less than 5 mm, a fibre length of less than about 4 mm, a fibre length of about 3 mm, a fibre length of less than 2 mm, a maximum mean fibre length of 3 4 mm, a mean fibre length in the range of to 1mm, a mean length of about 0.5mm, a fibre length distribution in the range of 6 mm to 1 mm, a fibre length of approximately 3 mm with less than 1% fibres greater than 4 mm, a fibre length distribution of less than 2% by wt fibres greater or equal to 4 mm, less than 4 mm and greater or equal to 2 mm between 5% and 50% by wt fibres and less than 2 mm between 5% and 50% by wt fibres. I OadcFM A process for making a reinforcing fibre as claimed in any one of claims 7 to 14, including the steps of: filtering the plurality of fibres having the polymerised coupling agent; and drying the filtered plurality of fibres.

16. A curable composite comprising a curable organic resin and a plurality of reinforcing fibres, each reinforcing fibre having a surface with no sizing agent thereon, wherein said surface of said reinforcing fibre is completely coated with a polymerised coupling agent and said fibre has a maximum fibre length of 6 mm.

17. A curable composite as claimed in claim 16, wherein said resin has an elongation at break, when cured, selected from the group consisting of greater than 6% and greater than

18. A curable composite as claimed in claim 16 or 17, wherein said resin is selected from the group consisting of epoxy vinyl ester resins, unsaturated polyester resins, vinyl ester resins, vinyl functional resins, tough vinyl functional urethane resins, tough vinyl functional acrylic resins, non plasticised flexible polyester resins and combinations thereof.

19. A curable composite as claimed in any one of claim 16 to 18, wherein the composite comprises reinforcing fibres selected from the group consisting of from to 60% by weight of said reinforcing fibres and from 30% to 50% by weight of said reinforcing fibres. A curable composite as claimed in any one of claims 16 to 19, which is sprayable.

21. A curable composite as claimed in any one of claims 16 to 20, which is pumpable.

22. A curable composite as defined in any one of claims 16 to 21 wherein the length of the fibre is selected from the group consisting of a fibre length of less than 5 mm, a fibre length of less than about 4 mm, a fibre length of about 3 mm, a fibre length of less than 2 mm, a mean fibre length in the range of 0.5mm to 1mm, a mean length of about 0.5mm, a maximum mean fibre length of 3 4 mm, a fibre length distribution in the range of 6 mm to 1 mm, a fibre length of approximately 3 mm with less than 1% fibres greater than 4 mm, a fibre length distribution of less than 2% by wt fibres greater or equal to 4 mm, less than 4 mm and greater or equal to 2 mm between 5% and 50% by wt fibres and less than 2 mm between 5% and by wt fibres. [1:\DAYLIB\LIBXXNiovN\Hodgson]AAUfiv2ai2OApri1Oadom:JFM 46

23. A process of making a curable composite comprising: mixing a plurality of reinforcing fibres with no sizing agent on the surfaces thereof with a solution comprising a polymerisable coupling agent so as to coat the surfaces of said fibres with the polymerisable coupling agent; polymerising said polymerisable coupling agent; filtering the plurality of reinforcing fibres having the polymerised coupling agent; drying the filtered plurality of reinforcing fibres; sieving the dried plurality of reinforcing fibres to break up agglomerates; and suspending the dried, sieved plurality of reinforcing fibres in a curable organic resin.

24. A process of making a curable composite comprising: mixing a plurality of reinforcing fibres with no sizing agent on the surfaces thereof with a solution comprising a polymerisable coupling agent so as to coat the surfaces of said fibres with the polymerisable coupling agent, wherein the length of the fibre is selected from the group consisting of a maximum fibre length of 6 mm, a fibre length of less than 5 mm, a fibre length of less than about 4 mm, a fibre length of about 3 mm, a fibre length of less than 2 mm, a maximum mean fibre length of 3 4 mm, a mean fibre length in the range of 0.5mm to 1mm, a mean length of about 0.5mm, a fibre length distribution in the range of 6 mm to 1 mm, a fibre length of approximately 3 mm with less than 1% fibres greater than 4 mm, a fibre length distribution of less than 2% by wt fibres greater or equal to 4 mm, less than 4 mm and greater or equal to 2 mm between and 50% by wt fibres and less than 2 mm between 5% and 50% by wt fibres; polymerising said polymerisable coupling agent; filtering the plurality of reinforcing fibres having the polymerised coupling agent; -drying the filtered plurality of reinforcing fibres; sieving the dried plurality of reinforcing fibres to break up agglomerates; and [I:\DAYLIB\LIBXX\NicovN\Hodgson]AUDiv2caims20Apri lOadoc:JFM 47 suspending the dried, sieved plurality of reinforcing fibres in a curable organic resin, wherein said resin is selected from the group consisting of epoxy vinyl ester resins, unsaturated polyester resins, vinyl ester resins, vinyl functional resins, tough vinyl functional urethane resins, tough vinyl functional acrylic resins, non plasticised flexible polyester resins and combinations thereof and said resin has an elongation at break, when cured, selected from the group consisting of greater than 6% and greater than A curable composite made by the process of claim 23 or 24.

26. A process of making a curable composite comprising: suspending, in a curable organic resin, a plurality of dried, sieved reinforcing fibres, each of said reinforcing fibres having a surface with no sizing agent thereon, wherein said surface of each of said reinforcing fibres is completely coated with a polymerised coupling agent and wherein each of said reinforcing fibres has a maximum fibre length of 6 mm. is 27. A process of making a curable composite comprising: suspending, in a curable organic resin, a plurality of dried, sieved reinforcing fibres, each of said reinforcing fibres having a surface with no sizing agent thereon, wherein said surface of each of said reinforcing fibres is coated with a polymerised coupling agent, said reinforcing fibres being in an amount selected from the group consisting of from 10% to 60% by weight of said reinforcing fibres and from to 50% by weight of said reinforcing fibres, the length of said reinforcing fibres being selected from the group consisting of a maximum fibre length of 6 mm, a fibre length of less than 5 mm, a fibre length of less than about 4 mm, a fibre length of about 3 mm, a mean fibre length in the range of 0.5mm to 1mm, a fibre length of less than 2 mm, a maximum mean fibre length of 3 4 mm, a fibre length distribution in the range of 6 mm to 1 mm, a mean fibre length in the range of to lmm, a mean length of about 0.5mm, a fibre length of approximately 3 mm with less than 1% of fibres greater than 4 mm, a fibre length distribution of less than 2% by wt fibres greater or equal to 4 mm, less than 4 mm and greater or equal to 2 mm between 5% and 50% by wt fibres and less than 2 mm between 5% and by wt fibres; wherein said resin is selected from the group consisting of epoxy vinyl ester resins, unsaturated polyester resins, vinyl ester resins, vinyl functional resins, tough vinyl [I:\DAYLIB\LIBXX\NicovMHodgson]A UDivi2cainis2OOApfliMa.doc:M 48 functional urethane resins, tough vinyl functional acrylic resins, non plasticised flexible polyester resins and combinations thereof and said resin has an elongation at break, when cured, selected from the group consisting of greater than 6% and greater than

28. A curable composite made by the process of claim 26 or 27.

29. A method of moulding a composite, said method comprising: locating a curable composite as defined in claim 16, to which a promoter and an initiator have been added, in a mould; curing said curable composite in said mould.

30. A method of moulding a composite, said method comprising: locating a curable composite as defined in claim 16, to which a promoter, an initiator and an air release agent have been added, in a mould; curing said curable composite in said mould.

31. A method of moulding a composite, said method comprising: locating a curable composite as defined in claim 16, to which a promoter, an initiator, an air release agent and a thixotrope have been added, in a mould; curing said curable composite in said mould.

32. The method of any one of claims 29, 30 or 31 wherein said locating comprises injecting.

33. The curable composite of claim 16 in combination with chopped rovings.

34. The curable composite of claim 16 in combination with chopped glass rovings wherein the composite is non air inhibited. A method of applying a laminate comprising: spraying a curable composite as defined in claim 16 or made by the process as defined in claim 27, to which a promoter and an initiator have been added, to form a bed; spraying a curable composite, as defined in claim 16 or made by the process as defined in claim 27, to which a promoter and an initiator have been added, and chopped rovings, onto said bed to form a layer; [1:\DAYLIB\LIBXX\NicovN\Hodgson]AUDiv2clairm20Aprilla.doc:JFM 49 spraying the layer of with a curable composite, as defined in claim 16 or made by the process as defined in claim 27, to which a promoter and an initiator have been added, to completely wet chopped rovings in the layer of repeating steps and until a layer of required thickness is achieved; and allowing said layers to cure and demoulding if necessary.

36. The method of claim 35 wherein the chopped rovings are chopped fibreglass rovings, the curable composite to chopped fibreglass rovings ratio is greater than 3 and the curable composite is non air inhibited.

37. A reinforcing fibre as defined in any one of claims 1 to 5 wherein the fibre has a mean length in the range 0.5mm to 1mm.

38. A plurality of reinforcing fibres wherein each of said fibres is as claimed in claim 1 wherein the fibres have a mean length in the range 0.5mm to 1mm.

39. A process of any one of claims 7 to 13, 15, 23 or 26 wherein the fibres have a mean length in the range 0.5mm to 1mm.

40. A curable composite of any one of claims 16 to 21, 33 or 34 wherein the fibres have a mean length in the range 0.5mm to 1mm.

41. A method of any one of claims 29 to 32, 35 or 36 wherein the fibres have a mean length in the range 0.5mm to 1mm.

42. A reinforcing fibre as defined in any one of claims 1 to 5 wherein the fibre has a mean length of about

43. A plurality of reinforcing fibres as claimed in claim 1 wherein the fibres have a mean length of about

44. A process of any one of claims 7 to 13, 15, 23 or 26 wherein the fibres have a mean length of about

45. A curable composite of any one of clams 16 to 21, 33 or 34 wherein the fibres have a mean length of about

46. A method of any one of claims 29 to 32, 35 or 36 wherein the fibres have a mean length of about

47. A reinforcing fibre as claimed in claim 1 and as exemplified herein. [I:\DAYLIB\LIHXX'I'icovN\Hodgson]AUDiv2clain200Aprilloadoc:JFM

48. A process for making a reinforcing fibre as claimed in claim 1 which process is as exemplified herein.

49. A cured composite as exemplified herein. A curable composite as defined in claim 16 and as exemplified herein.

51. A process for making a cured composite, as exemplified herein.

52. A method of applying a composite, as exemplified herein.

53. A method of moulding a composite, as exemplified herein.

54. A reinforcing fibre having a surface with no sizing agent thereon, wherein the surface of the fibre is completely coated with a polymerised coupling agent for coupling said fibre with a resin when cured wherein the reinforcing fibre is inorganic and is suitable for use with a resin which is organic, the coupling agent comprising a plurality of molecules each having a first end adapted to bond to the fibre and a second end which is adapted to bond to the resin and said fibre has a maximum fibre length of 6 mm.

55. A reinforcing fibre as claimed in claim 54, wherein said coupling agent has been selected from the group consisting of a polymerisable coupling agent and a coupling agent which has been at least partially polymerised before application thereof to the fibre.

56. A reinforcing fibre as claimed in claim 55, wherein said coupling agent has been at least partially polymerised after application thereof to the fibre.

57. A reinforcing fibre as claimed in any one of claims 54 to 56, wherein the coupling agent has been selected from the group consisting of an organo functional silane, an organic metal ligand and combinations thereof.

58. A reinforcing fibre as claimed in any one of claims 54 to 56, wherein the coupling agent is an organo functional silane.

59. A reinforcing fibre having a surface with no sizing agent thereon, wherein said fibre has a surface which is completely coated with a coupling agent for coupling said fibre with an organic resin when cured, said coupling agent being at least partially polymerised and said fibre has a maximum fibre length of 6 mm.

60. A reinforcing fibre as claimed in claim 59, wherein the coupling agent has been selected from the group consisting of a polymerised or partially polymerised [I:\DAYLIB\LIBXX\NicovN\Hodgson]AUDiv2ciaims200AprilI~adoc:JFM organo functional silane, a polymerised or partially polymerised organic metal ligand and combinations thereof.

61. A reinforcing fibre as claimed in any one of claims 54 to 60, wherein the surface of the fibre has been pre-treated with a metal oxide before application of the coupling agent thereto.

62. A reinforcing fibre as claimed in claim 61, wherein the metal oxide is selected from iron (III) oxide, iron (II) oxide, titanium dioxide, tungsten oxide, hafnium dioxide, nickel oxide, cobalt oxide, manganese dioxide, chromium trioxide, vanadium pentoxide, zinc oxide, molybdenum trioxide, tin dioxide, indium trioxide, niobium pentoxide, tantalum pentoxide and zirconium dioxide.

63. A plurality of reinforcing fibres wherein each of said fibres is as defined in any one of claims 54 to 62 and wherein the plurality of fibres has a mean length in the range 0.5mm to 1mm.

64. A plurality of reinforcing fibres wherein each of said fibres is as defined in any is one of claims 54 to 62 and wherein the plurality of fibres has a mean length of about A curable composite as defined in any one of claims 16 to 22 wherein said coupling agent is selected from the group consisting of silanes/acrylic functional, silanes/vinyl functional, silanes/styrene functional, organo functional silanes including organo functional silanes containing a carbon carbon double bond, transition metal acrylates, organic metal ligands and zinc diacrylate.

66. A curable composite as defined in any one of claims 16 to 22, 33, 34 or wherein said coupling agent is an organo functional silane coupling agent.

67. A process as defined in any one of claims 23, 24, 26, 27, 39 or 44 wherein said coupling agent is selected from the group consisting of silanes/acrylic functional, silanes/vinyl functional, silanes/styrene functional, organo functional silanes including organo functional silanes containing a carbon carbon double bond, transition metal acrylates, organic metal ligands and zinc diacrylate.

68. A process as defined in any one of claims 23, 24, 26 or 27, 39 or 44 wherein said coupling agent is an organo functional silane coupling agent.

69. A curable composite made by the process of any one of claims 23, 24, 26 or 27 wherein the resin to fibre weight ratio is in the range 2:1 to 4:1. rl \DAYLIB\LIBXX\NicovN\Hod2sonlAUDiv2cair 200ArdllOa docJFM 52 A method according to any one of claims 29 to 32, 35 or 36 wherein said coupling agent is selected from the group consisting of silanes/acrylic functional, silanes/vinyl functional, silanes/styrene functional, organo functional silanes including organo functional silanes containing a carbon carbon double bond, transition metal acrylates, organic metal ligands and zinc diacrylate.

71. A method according to any one of claims 29 to 32, 35 or 36 wherein said coupling agent is an organo functional silane coupling agent.

72. A reinforcing fibre as defined in any one of claims 54 to 56, 59 to 64 wherein said coupling agent is selected from the group consisting of silanes/acrylic functional, silanes/vinyl functional, silanes/styrene functional, organo functional silanes including organo functional silanes containing a carbon carbon double bond, transition metal acrylates, organic metal ligands and zinc diacrylate.

73. The process of any one of claims 7 to 15, 23 or 24 wherein said mixing comprises: mixing a plurality of fibres with no sizing agent on the surfaces thereof with a solution comprising a polymerisable coupling agent so as to completely coat the surfaces of said fibres with the polymerisable coupling agent.

74. The process of any one of claims 7 to 15, 23, 24, 26 or 73 wherein the length of the fibres is selected from the group consisting of a fibre length of about 3 mm, a fibre length of less than 2 mm, a maximum mean fibre length of 3 4 mm, a fibre length distribution in the range of 6 mm to 1 mm, a fibre length of approximately 3 mm with less than 1% fibres greater than 4 mm, a fibre length distribution of less than 2% by wt fibres greater or equal to 4 mm. The curable composite according to any one of claims 16 to 19 wherein the resin to fibre weight ratio is in the range 2:1 to 4:1.

76. The process of any one of claims 23, 24, 26 or 27 wherein the resin to fibre weight ratio is in the range 2:1 to 4:1.

77. The process of claim 23 or 26 wherein the resin has an elongation at break when cured, selected from the group consisting of greater than 6% and greater than

78. The process of claim 77 wherein the resin to fibre weight ratio is in the range 2:1 to 4:1. [I:\DAYLIB\LIBXX.NicovN\Hodgson]AUDiv2claims2OOApd IOadoc:JFM Dated 10 April, 2003 PETER CLIFFORD HODGSON Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON [1:\DAYLIB\LIBXNiovN\HodgsonADiv2aii2OApill~a~doc:JFM