NL8302883A - METHOD AND APPARATUS FOR FORMING NON-WOVEN COURSES - Google Patents

Description

* N / 31,577-tM / id "*; i t. Method and apparatus for forming non-woven webs.

The present invention relates to a method and apparatus for making non-woven webs or mats.

Techniques for forming non-woven webs from at least substantially dry ingredients have long been known; however / with the advent of high energy costs, the desirability of using such techniques instead of wet molding processes * has become even more apparent. Nevertheless, significant problems have been encountered in preparing dry-formed web materials with a relatively uniform structure. This invention concerns certain special apparatus and method which can be used to prepare such uniform nonwoven webs.

Various patents are of particular interest in connection with the present invention. U.S. Patent 3,356,780 describes a cloth making apparatus. A mixture of fiber particles and binder is fed into a chamber where it is contacted with a rapidly rotating cylinder and a pressurized air stream. The rapidly rotating cylinder and the air throw the fibers into slowly rotating perforated cylinders, the interior of which has a vacuum. The fibers and binder form a mat on the cylinders which roll together to form a layered fiber material.

U.S. Pat. Nos. 4,097,209 and 4,146,564 relate to a device, respectively. process for forming a mineral wool fiberboard product. A mixture of mineral wool fibers and a binder is prepared and fed through a venturi in an air stream of relatively high speed so that the material mixture is entrained and fed to a mat forming zone. In the mat forming zone, the material is deposited on converging open wire meshes by extracting air through the open 22 wire meshes. The wire meshes are then converged to obtain a mineral wool fiberboard product. Unfortunately, the method and device according to 83 02 333! These patents feature that they are essentially limited to the production of relatively thick materials having very variable basis weights.

The object of the present invention is therefore to provide a method and an apparatus for producing non-woven webs with uniform basis weights. This object is achieved by the method described in claim 1 and by the device described in claims 2-8.

According to the invention, a mixture of a binder and fiber material is introduced into top zones of a mat forming zone. The mixture is crossed by a horizontal or upwardly directed air stream and entrained therein, then deposited on at least one open wire mesh by suction of the entrained air through this open wire mesh or wire meshes. By reducing turbulence and controlling the way the particulate material is deposited on the open wire meshes, uniform, nonwoven webs can be obtained which can be used in many ways to form multifarious construction products.

The present invention includes a method of forming a nonwoven web, which method comprises the steps of preparing a mixture consisting of a binder and predominantly inorganic fiber material, this mixture is fed into the upper zones of a mat forming zone from a first movable open wire mesh disposed in the lower zone thereof and, optionally, a second movable open wire mesh arranged to converge with the first open wire mesh 30 at a pinch opening therebetween, the mixture being introduced through a first opening so that it falls in and is entrained in a horizontally or upwardly directed air flow, which is introduced through a second opening in the mat-forming zone, the second opening having associated means for controlling the direction of the air passing therethrough, the adjustable entrainment air being extracted through the wire mesh or the wire in an adjustable manner meshes to selectively deposit the mixture thereon, with the second opening and the optionally applied second open wire mesh relative to the first 83 0: 2033 - 3 - X · *

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Open wire mesh are applied so that the mixture deposited on the wire mesh or wire meshes is deposited almost uniformly, the deposited mixture being stiffened to form a nonwoven web and the material compressed and cured.

The present invention also includes an apparatus for forming a nonwoven web, which apparatus comprises (A) preparation means for preparing a mixture consisting of a binder and mainly inorganic fiber material, (B) a mat forming zone which supply is related to the preparation means so that it absorbs the mixture, the mat forming zone having (1) a first opening in its upper zones, said opening having means for introducing the mixture therethrough, (2 a second opening arranged therein such that air introduced through the second opening is carried horizontally or upwardly so that it crosses and entrains the mixture therein, the second opening having means connected thereto to control the direction of air passes therethrough, (3) a first movable open wire mesh disposed in the lower zone of the mat forming zone, this wire mesh from the mat forming zone passes through a nip opening and, optionally, a second movable open wire mesh arranged to converge with the first open wire mesh at the nip opening, the optionally disposed second open wire mesh and the second apertures are arranged relative to the first open wire mesh so that the mixture is deposited almost evenly on these 30 wire meshes, (4) means for adjusting the entrainment air through the open wire meshes in an adjustable manner to selectively deposit the mixture thereon and (5) means for moving the first open wire mesh and the optionally applied second open wire mesh to the nip opening to form a nonwoven web of material and (C) means for stiffening and hardening this web binder.

The apparatus described in U.S. Pat. No. 4,097,209 has proven useful in producing mineral wool products of about 2.5 cm or more in thickness. Although clump formation of particles and 8T f * η · - -J a ± ü o o · *.

'* - 4 - v; the presence of wave patterns have caused some difficulties, these difficulties are not particularly important because the product obtained must have a thick size. However, when products of thinner size are desired, problems arise due to the presence of the clumps and waves which have been found to be virtually insurmountable.

Applicants herein have discovered that the primary cause of these problems is the sequential process of entraining the particulate material in the air stream and then introducing the entrained mixture into the mat forming zone. Rapid airflow is required to maintain entrainment. The feed mechanism that separates the mass of solids into individual particles and introduces them into the air stream attempts to develop a static charge on the particles. The rapid airflow in combination with the static charge results in turbulence and lump formation of the particles. Small clogs of material initially form on the walls of the venturi as well as in the forming chamber. When the clogs collect more material, two effects are obtained. First, the clogs break off periodically and are deposited on the open wire mesh. Second, the clogs attempt to channel the passing air and thus cause an uneven entry of the particulate material into the mat-forming zone. The latter effect, in combination with the rapid entry of the entrained material into the mat-forming zone

8 TT P. Π r> f \ T

i - 5 - "*" and across the surfaces of the open wire meshes, attempts to form uneven deposits and wave patterns in the material deposited on the wire meshes. The entrainment process is thus virtually excluded if uniform base weights are desired.

Surprisingly, applicants have discovered that significant improvements in base weight uniformity can be achieved by separately introducing the particulate matter and airflow into the mat forming zone and making other important changes in the known process. By variably directing the airflow horizontally or preferably upwardly into the particulate material fed through an opening located in the upper zones of the mat-forming zone so that the particulate material crosses and is entrained in the airflow and through the open wire meshes and Placing the apertures relative to each other so that the entrained particles do not attempt to pass at high speed in parallel across the surfaces of the open wire meshes prior to deposition, the problems of non-uniform deposition are reduced dramatically. As a result, uniform webs with uniform basis weights and thicknesses of the order of 1 mm can be produced on a routine basis.

The present invention will become apparent from the description of preferred embodiments that follow.

Fig. 1 illustrates an apparatus for preparing a nonwoven web according to the present invention, which apparatus comprises means for preparing a mixture consisting of a binder and fiber material, a mat forming zone and means for processing the mat which is produced.

Fig. 2 illustrates an end view of a mat forming zone according to the present invention taken along line D-D of FIG. 1.

Fig. 3 illustrates a top view of a preferred aperture through which air enters the mat forming zone.

Fig. 4 illustrates a device consisting of two mat forming zones according to the present invention.

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The preferred device used to practice the present invention is illustrated in FIG. 1. Several features thereof are described in United States Patent 4,097,209, especially the means for preparing the particulate mixture and the curing and finishing agents. Mineral wool is typically received in bales 10 which must be cut into pieces before use. Fig. 1 illustrates bales 10 resting on a conveyor 11. The bales are partially sectioned at 12, transferred to the inclined conveyor 13, and then fed under a flail 14 causing an initial separation of the bales 10 into fibers 15. From the conveyor 13, the fibers 15 fall onto a conveyor 16 and are then fed onto an inclined pin-fed feed conveyor 17. At the top of the conveyor 17, the fibers are combed by a rotary comb 18 whereby the feed is leveled. The supplied material is thrown through the roll 19 into a gravimetric feeder 20 which is provided with a trough 21, compression rollers 22 and 23 and a flow rate balance 24. The device 20 feeds the fibers 15 through feed rolls 25 and 26 on a combing roller 27. The combing roller 27 drops the fibers 15 onto a conveyor 30 which places them under a binder supply station. 31 performs. The binder feed station 31 also includes a gravimetric feeder (not sheared) and deposits a desired amount of binder 32 on the fibers.

15 which are fed to the conveyor 30. The layered fibers 15 and the binder 32 are mixed by a comb roller 33 and then fed into a shredder 34 of a first opening 35 of a mat forming zone 36. The shredder 34 includes feed rolls 40 and 41, a retraction roller 42 and a pick-up brush 43.

The mat forming zone 36 with the exception of wire meshes 45 and 46 is constructed where possible from material 35 which is substantially electrically non-conductive such as plexiglass. Although some metal parts are required for constructional and other purposes, electrically conductive surfaces cause the deposition of statically charged particles on these surfaces. So they should be avoided whenever possible. Open wire meshes that are usually con-8 "'Λ i λ

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% constructed from a conductive material and the application of

such material for the lower wire mesh 45 is preferred. However, a wider choice is possible with the top wire mesh 46 and may be constructed of a non-conductive material such as plastic. Air enters the mat forming zone 36 through a second opening 44 and entrains the mineral wool / binder mixture. The entrained mixture is then felted on the first open wire mesh 45 and the second open wire mesh 46 as described below.

10 ven. The wire meshes 45 and 46 are brought together on one

pinch opening 47 / at which point the felted mixture becomes I

reinforced in a reinforcing zone 48. Before exiting from the reinforcing zone 48 at the pinch opening 49, an upper tamping device 50 and a lower anti-static device 51 promote separation of the reinforced material from the open wire meshes. The reinforced mate- I

material passes over transfer rollers 52 in an oven 53 where it can be dried, cured or the like. I

Although the mat forming zone 36, as shown, includes a first open wire mesh 45 and a second open wire mesh 46, which is preferred, it should also be noted that in some cases it may be possible to omit the second open wire mesh 46. The wire mesh 46 would thus be I.

for example, can be replaced by a panel of non-conductive material or a dense wire mesh. Nonwoven webs produced using the device comprising only an open wire mesh may in some cases have relatively more random particle size distributions than webs produced using an apparatus comprising two such wire meshes. Nevertheless, in many cases, and especially in the production of core building boards, the random distribution of particles makes little difference in the final product.

When such changes are applied, other changes to the device will also be required. For example, if the second wire mesh 46 is replaced by a panel, the reinforcement of the felted web could be done very suitably at the pinch opening 47 using a sealing roller. Furthermore, the absence of an upper wire mesh in the reinforcing zone 48 would in most cases obviate the ramming device 50, the primary function of which is to separate the web from this top wire-5 mesh.

In the preferred embodiment shown in Figs. The wire mesh 45 in direction A passes through the lower zone of the mat forming zone 36, while the wire mesh 46 enters into the mat forming zone 36 by passing around the wire mesh roll 58, and moves in the direction B to the nip opening 47 and exits the mat forming zone 36 by passing around the wire mesh roll 59. The open wire meshes 45 and 46 are provided with means 60 to 63 for drawing air through these wire meshes. The mat forming zone 36 also includes ceiling sections 64 and 65, a hood 66 in which the felting device 34 is mounted, a rear panel 67 and side panels 68 and 69 (Fig. 2).

The second opening 44 is provided in the rear panel 67 and is oriented upwardly so that the air supplied into the mat forming zone 36 through this opening generally passes in the direction C. It is also possible to allow the air to enter through the opening 44 in a horizontal manner; however, a less satisfactory felting is achieved with a horizontal embodiment. Furthermore, as a warning, downward directing of the air through the opening 44 should be avoided because extremely poor results are often obtained.

Although shown in Figs. preferred preferred embodiment shows openings 35 and 44 as individual openings, the present invention also encompasses those devices which, for reasons of dimensions or otherwise, comprise multiple openings which allow the particulate material or air into the mat forming zone. Thus, the use of single terminology herein will be understood to include a multiple of the indicated device.

Preferably, the second opening 44 will also include means for variably controlling the direction of the incoming air as it enters mat forming zone 36. Oscillating blades have been found particularly suitable 40 and shown in FIG. 2 and 3, wherein FIG. 2 is 8302883 - 9 - '

t I

taken along lines D-D of FIG. 1 and FIG. 3 an upper I

is view of the second opening 44. I

The second opening 44 consists of side panels 73 and 74, a top panel 75 and a bottom panel 76, I

5 at the two ends of this opening are open. Within the I

a row of blades 77 is provided at the opening. Sheets 77 are I.

mounted on pins 78, which rotatably engage the I

top panel 75 and bottom panel 76 so that blades 77 I

swivel about the axes of the pins 78. The ends of the blades I

The furthest from the mat forming zone 36 are connected to a blade oscillation axis by connectors 80.

Although the sectioned blade design is particularly suitable I

has been found to control the direction of the air flow, other flow control means provided in or j

15 behind the second opening 44 or in the mat forming zone 36 also with I.

advantage be applied. All these air control means become I.

thus contemplated by the present invention. I

During operation, the first open I

wire mesh 45 and the second open wire mesh '46 moved in the I.

20 direction A resp. B (Fig. 1), so that they converge at the I

pinch opening 47. Suction means 60, 61 and 62 suck air I

from the mat forming zone 36 through the first open wire mesh and off

suction means 63 suck air through the second open wire mesh.

The extracted air is replaced by air entering the mat forming zone through the second opening 44. Thus, an underpressure is always maintained in the mat forming zone 36.

Mineral wool is the preferred inorganic fiber material for practicing the present invention, but other fibers can also be used. Examples of such material are inorganic fibers of glass, ceramic material and wollastonite, natural fibers such as cotton, wood fibers or other cellulosic materials and organic fibers such as polyester or polyolefins. Furthermore, other materials such as perlate and different clays can also be used.

When a mixture of binder and pres I

namely, inorganic fiber material is introduced through the first opening 35, it is crossed by the upwardly directed air entering through the second opening 44. The 40 blade arrangement of the second opening 44 channels at 83 0 2 3 3 3 "fc - 10 -> * variable mode the air and the opening 44 is directed such that the air crosses the mixture of material immediately below the first opening 35. The resulting entrained mixture of material is deposited on the first 5 and second open wire meshes 45 and 46 as the entrainment air. is extracted by these threads The manner in which the air is extracted by these threads can be varied as desired by those skilled in the art to obtain products with different properties Although a single aspirator may be used behind each wire mesh, Figs. extraction means 60/61 and 62 / which are arranged under the first open wire mesh 45. The air extraction can thus be performed in two ways and varied, namely by varying the amount extracted by the different zones of a single wire mesh, for example, through means 60, 61 and 62 and by varying the relative amounts extracted by the top and bottom wire meshes 46 and 45.

Fine particles lighter than large particles try to follow the airflow and are therefore felted on those parts of the wire mesh through which most of the air is extracted. Thus, for example, if 90% of the air is extracted through one wire mesh, most of the fine particles will be deposited on that wire mesh. Layering and basis weight control will also be affected by variable suction of air through different parts of a single wire mesh. It will therefore be clear that if thin strips are desired, variable extraction of the air via means 60, 61 and 62 is very advantageous. Under these conditions, most of the air is preferably extracted through the wire mesh 45 to the rear of the mat forming zone by using the suction means 62, while smaller amounts are extracted by using the suction means 60 and 61. Variable suction is a another way to avoid turbulent passage of the entrained material across the surface of the wire mesh 45 at the pinch opening 47, the consequences of which are indicated below.

40 Variable air extraction also provides a 3 y i ό 3 o - li - alternative for replacing the second open wire mesh 46 with a panel or closed wire mesh. Thus, by depositing the suction means behind the wire mesh 46, almost all air will be extracted through the first open wire mesh 45. However, this alternative is not entirely satisfactory because even if all the air passes through the wire mesh 45, part of the particulate material will stick to the wire mesh 46, leading to some thickness variation in the resulting product.

A major drawback of the device described in US Pat. No. 4,097,209 was the lack of uniformity of the material obtained. A number of factors contributing to the unevenness have been explained above; however, another factor not mentioned is the narrow angle between the converging open wire meshes. Due to this narrow angle, as the entrained material enters the mat forming zone, the particulate material streaks across the surfaces of the open wire meshes at high speed. This turbulent passage coincided with the static charges present on the entrained material, resulting in wave patterns in the deposited material.

For these reasons, the angle between the wire meshes 45 and 46 at the pinch opening 46 should be such that turbulent passage of the entrained material across the surfaces of these wire meshes is avoided. The angle illustrated at the pinch opening of the device described in U.S. Pat. No. 4,097,209 is about 12 ° however, according to the present invention, it has been found that angles of not less than about 20 ° are preferred. Furthermore, the angle should not be too great because material deposited on the wire mesh 46 tends to crack or fall off the wire mesh as it passes around the wire mesh roll 59 specially produced as 35 thick mats. Thus, a maximum angle of not more than about 55 ° is preferred.

In addition to the horizontal or upward supply of air through the second opening 44 referred to previously, another factor that influences the way in which the particulate material is deposited on this open 83 0 2 3 3 3 .....

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4. wire mesh the place where the second opening 44 is made in the rear panel 67. If the point of intersection of the incoming air and the particulate material is too far below the opening 35, an appropriate entrainment cannot occur and the particulate material with a relatively flat angle pass over the first open wire mesh 45. Both effects promote wave patterns and unevenness. Thus, it is preferable that the second opening 44 is provided in the upper parts of the back panel 67.

Similar problems can also arise if the second opening 44 is facing down into the particulate material or if it is too far from the first opening 35. For a device constructed as illustrated in Figs. and having an approximate size as described below, it has been found that the best results are obtained if the distance between the first opening 35 and the first open wire mesh 45 is not less than 90 cm and if the distance between the inner end of the second opening 44 and the point where the upwardly directed airflow crosses the material-mixture is about 60 cm.

While these results can be varied somewhat by increasing the angle on the pinch opening 47, this angle and the location of the second opening 44 can both be varied to achieve the same result. Thus, it should be borne in mind that it is desirable for the particulate material to approach the surfaces of the open wire meshes 45 and 46 in a non-turbulent and approximately non-parallel manner.

The blades disposed in the second opening 44 make a particularly valuable contribution to the present invention. The build-up of wave patterns with time in the prior device was due in part to channeling caused by the statically induced deposition of the particulate materials in different parts of the passage through which the entrained material passes, and in part in the manner in which the entrained material passes over the material previously felted on the open wire mesh. The blades 77 attempt to overcome this problem by oscillating back and forth. If 40 axis 79 oscillates back and forth generally along the TT Λ Λ jWj 07 Ö v \ J $ «3

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lane EF (Fig. 3), the blades are first directed to an 'I.

side of the mat forming zone 36 and then to the other side of I.

this zone. As a result, there is little chance of channeling I.

and the particulate material deposited on the open wire

5 gauzes 45 and 46 is much more even. I

The advantage of the present invention I

can be clearly seen from the nature of the material that I

produced with the present device according to the present method. As indicated previously, only 10 relatively thick products could be obtained using Application I.

of the former establishments. For example, when a mix I

binder and mineral wool fiber is entrained in I.

an air flow and conducted into the mat forming zone described I

In U.S. Pat. No. 4,097,209, I

15 materials with a thickness of about 2.5 cm or more and with I.

many uneven zones obtained. Thick products can I

also obtained according to the present invention but I

these can be produced with high line speed and I.

they have none of the clogs or wave patterns that I own

20 to the products of the prior art

niek. j

As another example of the advantage of the I

present invention were attempts according to the known I.

state of the art to obtain thinner materials totally unsuccessfully due to the clogs being used

found in the finished product. Such difficulties arise I.

not with the present invention. Non-woven webs I

with uniform basis weights and thin design are I.

obtained using the present device wherein I

30 is performed in the present method. The benefits I.

of these thin material layers are remarkable. For example I

by using two mat forming zones as described herein

it is possible to produce sandwich-like construction products

shapes with thin outer layers and a central core. An advance I

The image of such a device is illustrated in I.

Fig. 4, wherein the means for preparing the particulate I

mixture and the curing and finishing agents are not finished. I

statue. I

A lower mat forming zone 83 and an upper I.

4.0 mat forming zone 84 are constructed as previously described, I.

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i - 14 - and as with the individual mat forming zones, they can contain one or two open wire meshes as desired. Mixtures of binder and a suitable fiber material are supplied to each zone and are converted into webs of material as described previously. The webs exit from zones 83 and 84 at the pinch openings 85, respectively. 86. The bottom web 87 is fed from the conveyor 88 over transfer rollers 89 to the conveyor 90. A core deposition station 91 then deposits a core mixture 92 on the web 87 and a thickness gauge 93 levels the core material. Station 91 includes a gravimetric feeder (not shown) such as that previously described.

Meanwhile, the top cock 94 exits the pinch opening 86, passes over transfer rollers 95 on the conveyor 96 and down the chute 97 depositing it on the top of the leveled core mixture. The loose composite material can then be compressed by a pre-compression assembly 98, ip in which case it exits from the pinch opening 99 as a structure of sufficient strength to be able to transport it through further processing and curing steps without undergoing significant damage.

A wide variety of products can be obtained by using this device. For example, if a mixture of expanded perlite and binder is used as the core mixture, the products produced can be varied from those having good acoustic properties to those having high fracture values. Furthermore, the plate is produced in a single pass operation 30, which is special. The prior art teaches that some sandwich-like products can be produced by separately making the outer layers and then adhering them to a core material with a layer of adhesive. The present invention is remarkably more favorable not only because of its simplicity in avoiding the adhesive layers but also because the nature of the process allows differential compaction of the product without resorting to separate laminating and pressing operations.

The aforementioned product, which is of a perlite core, is a particularly good example of this phenomenon. The outer layers of mineral wool and binder have a low compressive strength, while the expanded plating core has a relatively high compressive strength. When the composite structure is compressed, the core acts as an anvil against which the outer layers are compressed. This leads to compaction of the outer layers, but virtually no compaction of the core. At the same time, the core absorbs irregularities in the outer layers, whereby smooth outer surfaces with uniform density are obtained.

Another method of differential compaction of the composite structure involves successively curing the core and the outer layers. For example, if a composite structure is made with a core with a binder that has a lower curing temperature than the binder for the outer layers, and the composite is passed through a convection oven set at a temperature close to the core material hardening but not the outer layer bonding material, a structure is obtained with uncured outer layers. If these outer layers are then pressed against the core and cured, very dense outer layers can be obtained. Likewise, the same effect can be obtained by using binders with similar curing properties but with a necessary curing component omitted from the outer layer binder. When the necessary component is then added and the composite material is compressed and cured, dense hard outer layers are again obtained. An example of the latter alternative is the use of a binder such as a novalak phenol formaldehyde resin from which the cross binder hexamethylene tetramine has been omitted.

These and a variety of other structures with different characteristics can be produced according to the present invention. Other advantages of the present invention will become even more apparent with reference to the following examples.

Example I

This example illustrates the preparation of a product with about 87% mineral wool and 13% powder 8332883. . . The phenolic binder, wherein the product obtained has a thickness of about 3.8 cm and a density of about 96 kg / m. The product was manufactured using the dual baking mold zone device as shown in FIG. -4. Reference numbers refer to the numbers used in Figs. The lower mat forming zone 83 used for this and the following examples was constructed from plexiglass so that the distance between the pinch opening 47 and the back panel 67 is about 272 cm, the zone width measured between the side panels 68 and 69 was about 65 cm and the height measured vertically between the wire mesh 45 and the center point of the retractor roller 42 was about 105 cm. The angle of the pinch opening 47 was about 25 °. The top mat forming zone 84 had a distance between the pinch opening 47 and 15 the rear panel 67 of about 210 cm, the width and the height were about the same as for the mat forming zone 83.

The angle at the pinch opening 47 was about 48 °.

For each mat forming zone 83 and 84, mineral wool fibers were separated and fed to the conveyor 20 at a rate of 3.44 kg per minute using a Vectroflo gravimetric feeder. The phenolic resin was fed to the fiber through the station 32 at a rate of 1.02 kg per minute. This material was mixed together by the comb roller 33 and fed to the various shredders 34.

The wire meshes in the respective chambers were converged at about 3 m per minute and air was supplied to the respective chambers at a volume of about 142 m3 per minute and extracted through the forming wires 45 and 46. The pressure within each forming chamber was about 5. 3 cm of water under atmospheric pressure, measured using a Dwyer meter. In the lower molding chamber, approximately 90% of the entraining air was extracted through the lower molding wire mesh 45, with most of this air being occluded by the suction means 62. In the upper molding chamber, approximately 60% of the air was aspirated through the upper molding wire mesh 46 with no attempt to variably extract the air. The blades 77 were oscillated within each opening 44 at about 30 cycles per minute.

40 The mat materials were converged 3302883 * i - 17 - ·· "" at the pinch openings 47 and reinforced in the reinforcement zones 48. Immediately prior to exit from the reinforcement zones 48, the composite materials were simultaneously rammed by the ramming devices 50 and exposed to the anti-static devices 51. The ramming devices 50 were adjusted to hit the back of the wire mesh 46 approximately 30 times per minute, alternately compressing and releasing the mats, which assist in reducing mechanical adhesion. Static devices 51 were conventional alpha particles emitting devices which remove the charges from the fiber mats and reduce static adhesion. When these devices were used individually or not at all, complete separation of the mat materials from the wire meshes was not obtained. to apply however, these devices have produced good separation, resulting in high quality products.

The individual webs exiting from the mat forming zones 83 and 84 were converged and pre-compressed using the pre-compression assembly 98. This device was adjusted so that the pinch opening contacts the reinforced web very lightly. The stiffened material was then fed into a continuous convection dryer oven (TCD) and exposed to the air heated at about 205 ° C for about 3 minutes. During this exposure time, the resinous binder was melted and at least substantially cured. The distance between the pressure conveyors of the TCD oven was about 3.9 cm; therefore, when the plate emerged from the TCD-over in a slightly plastic state, it was recalibrated and cooled. Post-calibration adjusted the thickness of the plate to about 3.8 cm and cooling with the ambient air simultaneously reduced the plate temperature to slightly less than 121 ° C. The product produced in this way without the use of an after-calibration device was found to be a thickness variation of ± 1 mm, while material produced using the post-calibrator was found to have a thickness variation of ± 0.25 mm.

40 The acoustic performance of products formed in this way was: sound insulation class (NIC) of 20 and sound reduction coefficient (NRC) of 95. Thus, it was suitable for a variety of high performance acoustic applications.

Example II

This example illustrates the manufacture of a sandwich-like product with an overall composition as follows;

Weight Percent 10 Ingredient (solids base) mineral wool - 24.21 powdered phenolic binder 1.82 expanded perlite 64.35 liquid phenolic resin. 9.62 The outer layers consisted of 93% mineral wool and 7% powdered phenolic binder, while the core mixture consisted of 87% expanded perlite and 13% liquid phenolic resin.

Mineral wool fibers were fed to the conveyor 30 of the upper and lower molding systems 83 and 84 at a rate of 1.12 kg per minute. Powdered phenolic resin was then fed to the conveyor 30 through station 32 at a rate of 0.084 kg per minute. This material was mixed together with the combing roller 33 and fed to shredders 34 of each mat forming zone. Except as noted below, the operating parameters were the same as those set forth in Example I.

The mineral wool binder compositions were fed to the respective mat forming zones and felt on the open wire meshes 45 and 46 substantially as described in Example I. In this case, however, the air was extracted at different rates through the open wire meshes in the lower chamber; thus, approximately 75% of the air was extracted through the lower mold wire mesh 45 from zone 83 and approximately 25% was extracted through the upper mold wire mesh 46. The static pressure in each of these chambers was approximately 4.5 cm of water under atmospheric pressure , measured using a Dwyer meter.

The mats were converged at the respective pinch apertures 47, reinforced in compression zones 48, 40 treated with ramming devices 50 and anti-static in direction 51 and then fed to the pre-compression rollers 98. After the bottom mat was transferred to the conveyor 90, a mixture of 23% liquid phenolic resin and 77% expanded perlite was deposited through the addition station 91 on the sub-mat at a rate of 4.3 kg per m2 (wet base). The core mixture was leveled with the scraper mold 93, combined with the top mat 94 and reinforced using the pre-compression rollers 98. The height of the pre-compression rollers at the entry point was about 3.3 cm above the conveyor 98, while the opening nip 99 had the height about 1.4 cm. This caused the exiting material to be extruded through the narrow pinch opening.

The thickness of the pre-assembled material obtained was about 1.8 cm.

The pre-compression served to impart to the resulting unpaved sheet a sufficient strength and edge formation so that the sheet could be conveyed by the following preheating and curing operations without loss of perlite from the core or damage to the composite material. After pre-compression, the plate was transferred to a TCD device such as that illustrated in Fig. 1; however, the top compressors were not used in the manufacture of the cored product. The purpose of the TCD device was to preheat the cored product with a downward flow of air, thus causing significant drying and curing of the core mixture while leaving the outer layers virtually uncured.

Thus, the temperature of the air in the TCD oven 30 remained below 149 ° C, a temperature at which the outer layer binder did not set. A period of about 2 minutes was used for preheating.

In the preheating step, the plate was cut into pieces and fed through an accelerator conveyor to a flat bed press. Due to the desired thickness of about 1.6 cm for the product, suitable stops were used in the press to ensure that no excessive compression occurred. The final cure temperature was 232 ° C, although variations between 177 ° C and 288 ° C could be used. Residence time- 8502083 - 20 - ..

\.

Fourths in the press ranged from about 15 seconds to about 15 minutes, although a compression time of 1 minute and 30 seconds gave good results at 232 ° C. Optionally, a hand press could also be used for the final curing and pressing steps.

The obtained sheet had a total length of 1.6 cm and a density of 317 kg / m3. The thickness of each of the top and bottom skins was approximately 0.1 cm and the core thickness was 1.4 cm. The density of the outer layer was approximately 550 kg / m3, while the core density was approximately 252 kg / m3.

Example III

This example illustrates the manufacture of a pressed sandwich-like building board. The product 15 was manufactured in exactly the same manner as described in Example II up to the point where the uncured sheet emerges from the pre-compression rollers 98. In this case, the material was transported into the TCD device and air was passed through the sheet of the bottom to the top-20 side. Due to the reverse flow, the top compression means is set to lightly touch the top surface of the plate to prevent lifting or kinking due to the upward pressure of the airflow.

As a result of this treatment, curing occurred from the bottom of the plate upward and conditions were set so that the curing occurred within 1.6 mm - 6.4 mm of the top surface of the core material.

Following the preheating step, the plate was cut into pieces and fed to a flat bed press, the top plate of the press being provided with an insertion plate. The press was set so that the indentation plate penetrated only into the top uncured zone of the plate. As described for Example II, a temperature of 232 ° C was used for a residence time of 1 minute and 30 seconds. The density and basis weight values were almost the same as for the product of Example II.

Example IV

This example illustrates the manufacture 40 of a sandwich-like product with a thin moisture-resistant 83 C 333 4-21 -> c interior of high density. The total composition was as follows:

Weight percent

Ingredients (solids base) 5 mineral wool 34.14 phenolic binder powder 6.10 cement grade perlite 50.76 urea-formaldehyde resin 9.00

The outer layers consisted of 85% mineral wool and 15% powder-phenolic binder, while the core blend consisted of 85% cement grade perlite and 15% urea-formaldehyde resin.

The plate was manufactured almost as described in Example II, but because the desired final thickness was 4.76 mm, the stops in the pre-compression device were set at 4.56 mm. The obtained sheet had a density of 673 kg / m3 and a basis weight of 3.21 kg / m2.

The weight of the outer layers was 1.92 kg / m2.

Example V

This example illustrates the manufacture of a damage resistant board with wood fiber material. The total composition of the record was as follows:

Weight percent

Ingredients (solids base) 25 mineral wool 22.17 powdered phenolic binder 3.87 expanded perlite 48.10 de-sapwood fiber 11.08 liquid phenolic resin 14.78 30 This board was produced in the same manner as described in Example II to describe a product with a thickness of 1.59 mm and a density of 317 kg / m3. The total weight of the outer layers was 1.32 kg / m2. The presence of the wood fiber in this product had the effect of increasing the toughness of the board and reducing the effects of impact damage.

Example VI

This example, describing two alternative changes, further illustrates the technique of sequential curing. The basic procedure was similar to that used in Example II except that (1) the phenolic resin did not contain a hexamethylene tetramine curing agent and (2) the previously used core-5 binder was replaced with a starch powder.

The total composition of the plate, calculated on a dry basis, was as follows:

Weight percent

Ingredient (solids base) 10 mineral wool 24.21 powdered novalac phenol binder plus hexamethylene tetramine 1.82 expanded perlite 64.35 powdered starch binder 9.62 15 The outer layers consisted of 93% mineral wool and 7% binder based on the proportions indicated above. ingredients, while the dry core mixture consisted of 87% expanded perlite and 13% powdered starch.

The top and bottom layers were produced as described in Example II except that the powdery binder was added at a rate of 0.077 kg / minute due to the absence of the curing agent. Before adding the core mixture 25, it was wetted with water at a level of 19% based on the weight of the wet mixture. The wetted core mixture was then added through the core depositor 91 at a level of 4.8 kg / m2, the difference from the amount reported in Example II 30 being due to the added moisture.

After the added material was leveled with the smoothing template 93; the composite materials were reinforced with the top mat using the pre-compression rollers 98. The composite material was then transferred to a TCD device which, unlike the device in Example II, was steam-powered. The steam device was placed at the entrance of the TCD device and consisted of a steam distribution pipe above the plate and a vacuum device below the 40 plate under the TCD conveyor.

817 r, - ', η ^ -j ..ü ^ O 0 / Γ - 23 - t

As the plate passed in the TCD oven, the steaming device was used to draw steam into the plate at a rate sufficient to raise the temperature of the water in the core mixture above 82 ° C, where the starch gelled . The plate passed through the TCD device, where the core was dried and preheated in the usual manner. However, in this case it was possible to use temperatures higher than 149 ° C, because the binder in the outer layers did not contain the curing agent.

Following the gelling and drying steps, the plate was cut into pieces and fed into a spray booth. In this booth, a 10% solution of hexamethylene tetramide was applied to the top and bottom surfaces of the plate at a rate of 65 g / m2. The plate was then conveyed by an accelerator conveyor to a flat bed press and cured as described in Example II.

Under the action of the press, the hexamethylene tetramine disintegrated to release the formaldehyde curing agent, thereby setting the resin. The physical properties of the plate were almost the same as those measured for the product of Example II.

Pressed products can also be manufactured in the same manner and they provide the additional advantage of avoiding the partial pre-curing step set forth in Example III. Thus, when the top and bottom layers are cured in the presence of the hexamethylene tetramine solution, the water that evaporates softens the starch core binder, allowing it to be deformed to the desired embossed shape.

The invention is not limited to the described embodiments, which can be modified within the scope of the invention.

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Claims (8)

A method of forming a non-woven web, characterized in that a mixture consisting of a binder and mainly inorganic fiber material is prepared, the mixture is introduced into the upper zones of a mat-forming zone consisting of a first movable open wire mesh is disposed in its lower zone and, optionally, a second movable open wire mesh arranged to converge with the first open wire mesh at a pinch opening therebetween, the mixture being introduced through a first opening so that it falls into and becomes entrained in a horizontal or upwardly directed airflow introduced through a second opening in the mat forming zone, the second opening being provided with associated means for controlling the direction of the airflow passing therethrough, adjusting the entrained air in an adjustable manner aspirated through the wire mesh or wire mesh to selectively mix the mixture thereon with the second opening and the optionally arranged second open wire mesh disposed relative to the first open wire mesh such that the mixture deposited on the wire mesh or wire meshes is deposited substantially evenly, thereby strengthening the deposited mixture to obtain a nonwoven material web and the material is compressed and cured. 2. Apparatus for carrying out the method according to claim 1, characterized by (A) preparation means for preparing a mixture consisting of a binder and mainly inorganic fiber material, (B) a mat-forming zone, which is connected in the feed to the preparation means for receiving the mixture, the mat-forming zone having (1) a first opening in its upper zone, said opening being provided with means for introducing the mixture therethrough, (2) a second opening being therein 83 C 2 C 0 3 vr --- ίΓ - 25 - arranged that the air introduced through the second opening is directed horizontally or upwards so that it crosses and entrains the mixture, the second opening being provided with means connected thereto for controlling the direction of the air passing therethrough (3) a first movable open wire mesh disposed in the lower zone of the mat forming zone, the wire mesh exiting the mat forming zone through a pinch opening and, optionally, a second movable open wire mesh arranged to converge with the first open wire mesh at the pinch opening, the optionally disposed second open wire mesh and the second opening being arranged relative to the first open wire mesh so that the mixture is deposited almost evenly on the wire meshes, (4) means for adjustably drawing the entrainment air through the open wire meshes to selectively discharge the mixture thereon and (5) means for moving the first open wire mesh and the optionally applied second open wire mesh to the nip opening to form a nonwoven web and (C) means for stiffening and heating the web and for curing of the binder. 3. Device according to claim 2, characterized in that the optionally arranged second open wire mesh is replaced by a panel of non-conductive material. 4. Device according to claim 1, characterized in that the optionally arranged second open wire mesh is replaced by a closed wire mesh. 5. Device as claimed in any of the claims 2-4, characterized in that the air is extracted through the first open wire mesh using multiple suction means. Device according to any one of claims 2-5, characterized in that the means for controlling the air passing through the second opening consist of a blade assembly. Device as claimed in any of the claims 2-6, O 7 r. '~ Ci · * τ Ö ^ * _ _1 Γ' - 26 - <c A ö characterized by a ramming device, an anti-static device or a combination thereof which facilitates the separation of the web from the wire meshes. 8. Device according to any one of claims 2-7, 5, characterized in that the angle at the tilt opening is not less than about 20 ° and not more than about 55 °. 4 S3 02 883