DE10128549A1 - Plates, cords, or shaped parts completely or partially consisting of natural fibers or chips bonded with polyethylene and/or polypropylene binders useful in packaging applications with avoidance of moisture damage - Google Patents

Abstract

Plates, cords, or shaped parts completely or partially consisting of natural fibers or chips bonded with binding agents consisting of one or more synthetic plastic polymers, especially one or more thermoplastic synthetic materials such as polyethylene and/or polypropylene recyclates is new. Independent claims are included for: (1) a process for preparation of components as above by coextrusion of natural fibers and or chips and a binder from thermoplastic artificial plastic with thermal liquefaction; (2) a process for surface improvement of surface repair, especially of concrete panels, using a mixture of natural fibers or chips and one or more synthetic plastic polymers, especially artificial thermoplastics, e.g. artificial plastic polyethylene and/or polypropylene recyclates as binders; and (3) component consisting essentially of filler materials, e.g. solid materials such as solid wood, consisting of a mixture of natural fibers or chips, forming a surface improvement or surface repair layer with binder.

Description

The invention relates to a component designed as a plate, strand or molded body from binder-bound natural fibers or chips as semi-finished products or Finished product as well as manufacturing processes and surface finishing processes surface hardening or surface repair of such moldings according to Preamble of claims 1, 4 or 10.

Such components are used, for example, as transport or concrete formwork Plate application, being a binder of natural chips or fibers Glue is used. Likewise, the application is profiled or not pro Filleted strand material in the form of a rod for less bending-stressed applications possible cases. Both pressed and optionally come as components surface profiled panels as well as more complex components, such as Spacers in the packaging industry between the one to be packed Good and the actual packaging material, but also as packaging medium or for other uses, particularly those inexpensive basic materials are required. Such components are in the Re gel by drilling, sawing and other processing typical of wooden components operations editable.  

The well-known components made of wood chips and wood fibers, which, for example, as Chipboard or MDF are known to have the disadvantage that their Disposal because of the glue used to bind the fibers or Chips and curing of the component is problematic.

Concrete switchboards or trangsport packaging or pallets do exist Usually made of solid wood but you also have waste disposal pro problems. They are during the intended use as well as at improper storage often exposed to the effects of wet what swelling-related changes in shape can result. The again The usability of such components is therefore unsatisfactory. they are also burdened by a significant cleaning effort, e.g. B. because the concrete brought into contact with the surface in a liquid state or dirt to a considerable extent tends to open out Pore structure of the wood. It often happens that festge made concrete components from the surface of the fresh when stripping provided and still mechanically unstable concrete component broken out who the one that burdens its surface quality and complex and mostly little permanent repairs.

It is already known to avoid the disadvantages in this regard Surface of boards made of wood with a paint or wax coating or on to apply such a layer. The durability of such coating However, is unsatisfactory. The coatings require constant care. Concrete switchboards, transport packaging or pallets like them currently used by industry, so have a very low Zy klenzahl, which means that this z. B. in the field of exposed concrete production can only be used two to three times. Then the on application in areas that require subsequent finishing of the concrete surface Experienced. The refurbishment of such concrete control panels for reuse in  Fair-faced concrete is currently very expensive and mostly 4/5 of the new price consuming. As a rule, new materials such as paints, epoxy resins or plastic films for primary finishing or for repair purposes applies. As already described in the published patent application DE 42 01 319 A1, are particularly suitable for permanent coating and polyolefins here especially polyethylene.

Proceeding from this, the invention is based on the object for, as plates, Strands or molded parts designed components that are made entirely or partially the medium-bound natural fibers or chips exist, an environmentally to create sustainable disposal and the useful life before a Increase disposal if possible.

To solve this problem, it is proposed with regard to generic components propose as a binder one or more plastic polymers, in particular to use thermoplastic, especially plastic recyclate made of polyethylene (PE) and / or polypropylene (PP). Regarding a manufacturer a method with the features of claim 4 and a method of surface finishing or repair the features of claim 10 proposed.

The invention enables u. a. universal use of polymers Waste materials on construction sites, in manufacturers or in repair shops for Formwork elements and other components. So a feedstock is featured propose, which is currently very cheap to procure because it is Ver packaging materials from the material cycle of the Dual System Germany (DSD) can act. On the one hand, these are granules, such as those used in Bremen blast furnace process can be used for firing or polyolefin and polypropylene film packaging as currently in wax and paraffin producing companies. The advantage of the proposed Procedure exists u. a. in the inexpensive material base.  

As natural fibers or chips present in fiber or chip form on the one hand, those made of wood, for example in the form of Excelsior. There are also other natural fibers or chips, such as coconut fiber or coconut chips or other fibers or chips from renewable Natural products. "Chips" are in the sense of this invention Particles of different or similar sizes - with and without grain sizes distribution - up to and including fine-particle to powdery (like wood flour) particles to understand.

On the binder side, both pure polypropylene and pure polye prove to be ethylene, but in a special way also the recycling material mentioned Polyethylene and polypropylene or mixtures of the two.

In addition to the fibers or shavings from natural products that are not only the Bear Can also be used on conventional woodworking machines can significantly contribute to the bending strength of components manufactured in this way If necessary for further stabilization of the metal reinforcements in metal Fabric, wire or sheet metal can be used.

Natural fiber or chip components according to the invention can be used in many areas Chen application. Especially when it comes to interior work, as it is practical do not contain any pollutants that can escape during the period of use or after disposal after use, such as by burning, represent significant environmental pollution.

Components according to the invention are also in the construction sector for the ge The entire outdoor area is particularly suitable because it has a special whiff are resistant to weathering - especially without additional weather conditions Continuous surface treatment, because it u. a., not or only very much swell little. Other areas of application are garden and landscape  construction, e.g. B. palisades, the packaging industry, in the field of sound insulation (to the side of the highways), sound insulation in the area of impact sound insulation (Floors, etc.). It has been shown that the moisture on as well as the risk of rotting of the natural fibers used or Chips is comparatively low, because this is due to the use in particular special thermoplastic materials are sufficiently embedded as binders or be soaked. Therefore, components according to the invention also come for the so-called wet area of bathrooms, washrooms and shower rooms, such as Partitions or wall coverings, especially wherever a we less high-quality equipment but a particularly low price in the front reason stands.

Environmentally compatible disposal of components according to the invention can occur done in different ways. Also, a longer material life is Thermoplastic materials can be used as binders because of this allow forming into new components. Besides such a re refurbishment, is also a final disposal by burning pro without any problems.

In addition, it is also possible to use components according to the invention as more to design layered components that consist of a core and a surface layer consist. For example, wooden panels used as formwork panels can also be used the mixture of binder and natural fibers or chips become - both in the initial production and as a repair measure Restoring a smooth, resistant and moisture repellent send coating.

If it is uncoated new formwork panel elements, these can di be used directly. Is it brought in for repair Formwork panel elements, they must be removed from the interface (paint, Wax) can be freed and roughened. Then the panel elements  preheated to a temperature between preferably 50 ° C and 180 ° C. This superficial preheating ensures very good adhesion with the Recycled material achieved. The formwork panel element is then under a melt conveyed finely and with recycled material - preferably with natural fibers or chips intimately mixed - poured over. The temperature of this mass be bears preferably between 150 ° C and 400 ° C. To smooth this mass becomes a metal roll or cutter unit with a temperature between 150 ° C and 400 ° C over the surface, or the formwork sheet below transported through this tool. This is particularly easy System switchboard procedure, as this protrudes from the side of the Me have tall bracket over the wooden surface, which as a border for the mass to be applied can be used.

This procedure also makes it very easy to get damaged Compensate panel surfaces, cracks, breakouts and thus this ele elements in the exposed concrete area.

Components according to the invention have - in contrast to chipboard made of wood chips and glue or other glue as binders, a pleasant Impact and sound insulation due to a comparatively good elasticity.

In addition, components according to the invention achieve comparatively good ones Thermal insulation values.

Components according to the invention can also be colored if used as a binder used plastic polymer color pigments are added. So can for post-treatment with dye in the form of paints or spray, Dipping or other coating techniques can be dispensed with. Insbesonde There is no constant repetition of paints like those of the generic type state-of-the-art components are required.  

Basically, components according to the invention are manufactured by Einar the natural fibers or chips into the still liquid binder - or vice versa. Thermal liquefaction and shape is preferred using press pressure.

As a preferred manufacturing process, coextrusion of the natural Fibers or chips and the at least one polymeric plastic brief thermal liquefaction at temperatures above 150 ° C, preferably above 200 ° C. This processing temperature can be in Coextrusion devices, such as known screw compressors, on one comparatively short exposure time are limited, so that the Low risk of chemical changes in natural fibers or chips will hold. At the same time there is a very intensive impregnation or um sheathing the natural fibers or chips with the under these working conditions particularly viscous plastic. In the field of plastics processing Processing extruders with mixing section and heating section (if necessary with several heating zones) for such manufacturing methods and suitable Dü sink heads available. In addition, in the coextru invention sion are at least largely prevented when melting and Compressing atmospheric oxygen gets into the molding compound, making an oxidative Degradation, especially of natural fibers or chips (partial combustion) at least partially - if not completely - is excluded.

For most types of natural fibers or chips, it is recommended that Process conditions for coextrusion to be chosen so that the tempera Do not exceed 250 ° C and the dwell time in the zone of the highest Temperature is as short as possible.

Because under normal storage conditions wood depends on humidity and Temperature contains 5 to 10% water and this escape during extrusion would, it is to avoid gas inclusions in the extruded component of  The advantage of drying the wood at about 110 ° C before extrusion.

The aforementioned and the claimed and in the exemplary embodiments described components to be used according to the invention underlying in their size, shape, material selection and technical conception no special exceptions, so that in the application known selection criteria can be used without restriction NEN.

Further details, features and advantages of the subject matter of the invention result from the subclaims and from the following description exercise of the associated embodiments.

embodiments

The tests were carried out with a compact extruder E 19/25 D from Bra bender OHG with a three-stage screw (compression ratio 3: 1) and a nozzle head made for this purpose with an elongated hole geometry (16.8 mm). In order to achieve good miscibility with the plastic component and good flowability of the mixture, coarse spruce wood shavings (chip lengths of approx. 1 to 10 mm and diameter of 0.1 to 1 mm) were used; the type of wood is not decisive in these experiments; Fir wood sawdust accumulates in large quantities when processing wood. Two different plastics were used as binder components for the wood:
pure polypropylene (PP) (Novolen Targor NV1100N) and
Recycled material made of polyethylene and polypropylene PE / PP.

First, extrusion tests of dried wood chips with pure PP carried out the processing conditions recommended by Brabender OHG  conditions for PP are 210 ° C, 220 ° C and 230 ° C for the three wood zones of the Extruders and 240 ° C for the tool (nozzle). Because these temperatures are for Wood is too high (especially in the nozzle where the extrudate is in the air oxygen can come into contact) has been exposed to lower temperatures rimentiert. Table 1 shows selected test conditions in which the Processing temperature was kept as low as possible. In doing so the optimal temperatures of the extruder (3 heating zones) and the nozzle Right. The speed of the extruder and the ma ximal wood content (each in weight percent) determined.

Table 1

test conditions

The following are the observations for the individual test conditions conditions as well as the most important material properties of the extrudate wrote: In the beginning, processing temperatures were as low as possible conditions chosen to cause excessive thermal stress on the wood avoid.

Trial A1

At these low temperature settings the extruder and the nozzle are only a very small proportion of wood possible, since the viscosity of the mixture is very high is high. As a result, the extruder has to work with a high torque. Another problem is that the mass is in the compression zone  the snail and prevent the mixture from feeding in again that could. The shape of the extrudate is comparatively uneven and the properties correspond more closely to those of pure PP (very hard, brittle).

For these reasons, the temperature in the compression and high pressure zone in test A2 increased by 10 ° C. As a result, there was an increase of the wood content to 25% possible, the properties of the extrudate remained but essentially unchanged. In these conditions, every now and then again a temporary separation of wood and PP was observed, so that too these parameters have not yet appeared to be optimal.

Under the conditions in Experiment A3, the temperature of all three heating zones was and the nozzle significantly increased, which increases the proportion of wood to 33% allowed. However, these temperatures are already so high that a Browning of the wood occurred.

Because the torque is still very high and the wood content comparatively was low, an attempt was made with a lower nozzle temperature and with higher number of revolutions (shorter dwell time, better utilization of the Torque) (experiment A4). Under these conditions, a Wood content of 50% can be realized without causing a brown color of the Wood is coming. The extrudate thus produced fulfills the conditions mentioned conditions: it can be sawn, nailed, shows no swelling behavior in water and also has a very high strength. However, it receives many Air / Gas inclusions. The wood chips are very good in the plastic matrix embedded; the plastic encloses the wood chips and penetrates due to a high processing pressure in the structure of the wood. Because of the strong different bulk densities of wood and PP granulate (wood chips approx. 0.1 up to 0.2 g / ml and PP 0.5 to 0.6 g / ml is an even distribution of the haul zes in the feed area of the extruder is not yet optimal, which occasionally leads to leads to different distributions of the wood in the extrudate. By  a more suitable screw geometry with mixing and degassing zone these problems can be solved.

TRYING WITH PLASTIC RECYCLED (PE / PP)

Based on the tests with PP, the same temperature settings were made lungs and the same number of revolutions as selected in test A4. The egg Properties of this recyclate are optimal (viscosity, temperature behavior ten) that tests with 50%, 75% and 85% wood content were possible without that there were problems with extruding. The following are the Eigen described strands obtained:

The binder component, a gray granulate made of PE and PP, forms in the extru dieren a smooth strand, which, however, slightly when leaving the nozzle inflates. In the longitudinal section there are occasionally trapped air bubbles clear. This strand is elastic (nailable) and not nearly as brittle like pure PP. With a wood content of 50%, a gray strand can be ex trud, whose properties are still very similar to the binding component. The wood chips are evenly distributed and all around with plastic Ben Larger air bubbles occur mainly inside the strand. These air bubbles can either be from gas products from the source material fen or come from insufficiently compressed molding compound.

With a wood content of 75%, a true-to-impression strand can be extruded the. The strand is smooth and can be processed like wood. On the surface the individual wood chips can be recognized due to the high proportion of wood, which are no longer completely covered with plastic, so that the extrudate in the Water swells on the surface. The wood fibers are well incorporated into the plastic matrix bed and the plastic part between the individual chips is only very low. However, individual air pockets are also observed here. Due to the lack of a mixing zone of the screw, it can premixing the feedstock to a cluster of one or the other  Component come what lead to breakage of the strand.

If the proportion of wood is further increased to 85%, the proportion of plastic is sufficient usually no longer enough to connect the wood properly. The stability of the Stranges decreases significantly; in places the strand only holds in wood chips pressed together.

At the temperatures of 120 ° C, 220 ° C and 220 ° C for the three zones of the Extruders and at a temperature of 160 ° C for the nozzle can be made with PP Extrudates up to 50% wood content can be produced. These strands are very hard can be processed similarly to wood. They show no swelling behavior in the water. However, they are more difficult to extrude and contain many Air inclusions, which, however, are reduced by a suitable screw can be decorated.

Under the same conditions, plastic recyclate made of PP / PE Make strands up to a wood content of 85% without this being Pro blemen during extrusion. A wood content of 85% represents the technical Use may be an upper limit. The plastic content is there too small to "glue" the wood chips. With a wood content of 75% very good material properties are achieved. The strands show a little swelling behavior on the surface and on cut edges and leave processing similar to wood. Ver with increasingly less wood the properties of the strands are increasingly shifting towards the Plastic mixture. What proportion of wood for a desired application of the What is correct must be determined by the user. The Wood / recyclate mixture allowed through the use of different Wood shares a wide variation in material properties.

Claims (15)

1. As a plate, strand or molded part, which consists entirely or partially of binder-bound natural fibers or chips, characterized in that the binder consists of one or more plastic polymers, in particular one or more thermoplastic plastics, such as recycled plastics made of polyethylene and / or polypropylene. 2. Component according to claim 1, characterized in that the mixture proportion of natural fibers or chips is 25 to 85% by weight. 3. Component according to claim 1 or 2, characterized in that the component consists essentially of a solid material, such as solid wood, and the Mi natural fibers or chips and the binding agent create a surface surface treatment or surface repair layer. 4. A method for producing a component according to claim 1 or 2, characterized characterized by the coextrusion of natural fibers or chips and one binding agent made of thermoplastic under thermi shear liquefaction of the binder. 5. The method according to claim 4, characterized by a multi-zone heater extruder for coextrusion. 6. The method according to claim 4 or 5, characterized in that the thermal liquefaction at temperatures between about 150 ° C and  250 ° C takes place. 7. The method according to any one of claims 4 to 6, characterized in that that the natural fibers or chips are dried before coextrusion. 8. The method according to any one of claims 4 to 7, characterized in that as a binder a plastic recyclate, especially from a Mi consists of polyethylene and polypropylene. 9. The method according to any one of claims 4 to 8, characterized in that the co-extrusion takes place with largely no air. 10. Process for surface treatment or for surface repair, esp special of concrete control panels, characterized by the use of egg a mixture of natural fibers or chips and one or more Plastic polymers, in particular thermoplastics, such as Plastic recyclate made of polyethylene and / or polypropylene as a binder. 11. The method according to claim 10, characterized by the use of a Conveyor for concrete formwork panels and / or a melting device for the coating material and / or a post-treatment line Optimization of the applied surface layer. 12. The method according to claim 10 or 11, characterized in that the Binder is heated in a melting tank, in particular to about 150 ° C to 400 ° C and via an outlet on a preheated concrete control panel is spent. 13. The method according to any one of claims 10 to 12, wherein the applied Then mix with a metal roller or cutter unit at egg ner temperature between 150 ° C and 400 ° C is smoothed.   14. The method according to any one of claims 10 to 13, in which the plant supplied panel surface previously heated to approx. 50 ° C to 180 ° C becomes. 15. The method according to any one of claims 4 to 14, characterized in that as a binder recyclate from DSD waste plastic collections with a high polyethylene and / or polypropylene content is used.