WO1993017845A1

WO1993017845A1 - Process for producing pressure formed synthetic resin bodies

Info

Publication number: WO1993017845A1
Application number: PCT/AT1993/000037
Authority: WO
Inventors: Fritz Haunold
Original assignee: ISOVOLTA Österreichische Isolierstoffwerke Aktiengesellschaft
Priority date: 1992-03-04
Filing date: 1993-03-04
Publication date: 1993-09-16
Also published as: DE59300533D1; EP0585428B1; EP0585428A1; AU3620293A; AT397805B; ATE127065T1; ATA41392A

Abstract

A process for producing pressure formed synthetic resin bodies comprises (a) a pre-impregnation step and (b) an impregnation step. During (a), loose fibrous materials are intimately and uniformly mixed in the blow line (3) with a binder based on a condensation resin, then are dried in an overheated air flow (6) down to maximun 6 % residual humidity. During (b), the pre-impregnated wood fibres are loosedly piled (10) on a conveyor band (12) and are then laminated on both sides with the release papers (25, 25') coated on one side with the binder based on condensation resin. The thus produced laminated structure (19) is continuously compressed at a higher temperature up to an average mean specific weight between 900 and 1200 kg/m<3>, so that the binder completely penetrates into the fibrous mass, where it is then hardened.

Description

Process for producing a synthetic resin pressure-molded body

The invention relates to a process for the production of a synthetic resin compression molding, in which in an impregnation step 5 fiber materials, such as wood fibers in the form of a bed, are applied to a conveyor belt for the continuous production of a pre-compact or a raw plate and then, if appropriate, separating papers on both sides with a Binders consisting of a condensation resin or resin mixture based on phenols and / or amino compounds and aldehyde such as formaldehyde have been coated, and in which the layer structure thus formed continuously to an average weight per unit area in the range between 900 and 1200 kg / m ³

15 compressed and heated to a higher temperature at which the viscosity of the binder is reduced, so that the binder penetrates completely into the pore volume of the compressed fiber mass and is subsequently cured if necessary. 0 State of the art

Such a method is described in PCT / AT90 / 00042, which leads to pressure-molded articles which are used, for example, for the production of decorative synthetic resin high-pressure laminates for outdoor use, the water resistance and flame resistance being particularly great for outdoor use Meaning is.

Furthermore, it has been shown that one of the known

30 manufacturing process caused irregular resinification of the

Fiber material leads to a porous laminate, the

Water resistance is reduced. The resulting change

* alternating moisture content in the laminate leads to chip

-jf openings in the material, which in particular at the cut edges

^" 35 can cause cracks. Furthermore, the water resistance is reduced by the properties of the flame retardants used in the known method, since large amounts of water-soluble flame retardants are added to the binder, which are partially leached out in the wet area, in particular when the laminated sheet made by the known method is used, thereby causing further points of attack for moisture can arise.

Presentation of the invention

The invention is based on the object of specifying a method of the type described at the outset which brings about a laminate with improved performance properties with regard to water resistance and flame resistance.

This object is achieved by a method of the type described at the outset, which is characterized in that the loose fiber materials are intimately mixed with the binder in a pre-impregnation step, for example in the blowline 3, the surface of the loose fiber materials being regularly included the binder is coated, and that these pre-impregnated fiber materials are then dried in a hot air stream 6 to a residual moisture of at most 6% and that these dried, pre-impregnated fiber materials are then used in the impregnation step.

Another advantage of the invention is that in the pre-impregnation step, a solid, water-insoluble flame retardant which is dispersed in the binder can be added to the binder and this flame retardant consists essentially of a water-insoluble nitrogen compound or of a water-insoluble nitrogen-phosphorus compound and borate are added to this flame retardant, the amount of flame retardant applied being 5-20% by weight, based on the dry fiber material. The object of the invention is further achieved in that additional fiber materials in loose form and / or in the form of fabrics, scrims, mats, nonwovens or the like are added for the impregnation step and the additionally added fiber materials consist of glass fibers, synthetic fibers or natural fibers .

Another advantage of the process according to the invention is that a condensation resin or resin mixture in liquid form is used as the binder, which has a solid resin content of more than 80% by weight and a water content of at most 8% by weight, preferably at most 6 % By weight, the resin application in the pre-impregnation step being between 10 and 15% solid resin based on the dry fiber material.

Brief description of the drawings

The method according to the invention is explained in more detail with reference to FIGS. 1 a and 1 b, the pre-impregnation step being shown in FIG. 1 a and the impregnation step in FIG. 1 b, and an exemplary embodiment.

According to a device according to FIG. La, wood chips are softened with steam at approx. 170 ° C. and in

Refiner 1 chopped into wood fibers at a pressure of approx. 4 - 5 bar. These are discharged continuously via the blow valve 2 from the refiner into the blowline 3 under a high pressure drop, as a result of which a turbulent flow is generated. A binder, for example a phenolic resin with a low degree of condensation and consequently a relatively low viscosity, in which a solid flame retardant is dispersed, is introduced into the blowline 3 at a point 5 via a pipeline 4. For example, a water-insoluble ammonium polyphosphate can be used as the flame retardant. Due to the turbulent flow conditions in the Blowline 3 the wood fibers in the pre-impregnation step are coated with the binder provided with flame retardant up to an order of 15% based on dry substance. On the one hand, the free-floating fibers are wetted uniformly on their surface by the binder and, on the other hand, the particles of the flame retardant are glued to the fibers, so that a uniform distribution of the flame retardant is retained during further processing of these pre-impregnated fibers. These pre-impregnated fibers are then introduced into the dryer tube 6, which is fed with hot air by a hot air blower 7, and dried to a moisture content of, for example, 4%. The fibers thus dried are then introduced into a fiber bunker 9 via a cyclone 8 and can be stored there until the impregnation cut.

In the impregnation according to a device according to FIG. 1b, the pre-impregnated wood fibers in the form of a fiber bed 10 are applied to a conveyor belt 12 from the scattering station 11. Unimpregnated fibers of other types, such as glass fibers, can be added to the pre-impregnated fibers. The basis weight of the fiber fill is continuously checked by means of a balance 13. The fiber bed 10 is then pre-compressed in a pre-press 14, 14 '. Release papers 15, 15 'are drawn off from the supply rolls 16 and coated on one side with the highly viscous, water-free binder via the coating system 17, 17'. The basis weight is checked with a basis weight device 18, 18 *. The coated release papers 25, 25 'are now laminated on both sides to the pre-compressed fiber cake 19 with the coated sides towards the fiber cake. The structure thus formed then passes through a belt press 20 which is equipped with a heating zone 21 and a cooling zone 22. In the heating zone 21, the binder from the coatings of the release papers 25, 25 'penetrates into the fiber cake 19 from both sides. Since the fibers are evenly wetted with the binder from the pre-impregnation, the binder is distributed evenly in the spaces between the fibers. In order to prevent undesired curing of the binder, this composite is cooled in the cooling zone 22 to a temperature of at least 40 ° C. Subsequently, the release papers are pulled off via the rollers 23, 23 ', the band-shaped composite is cut to length in the cutting device 24 and stacked. If the length of the cooling zone 22 is not sufficient for the desired cooling, a cooling star can be connected between the cutting device 24 and the stacking.

10

In order to produce a plate-shaped, decorative high-pressure molded body with a thickness of 6 mm, a pre-pressed product made according to the process of the invention as the core material in a high-pressure press at 140 ° C. and 70 bar for 20 minutes between two decorative papers impregnated with melamine resin pressed, whereby the resins contained in the pre-compact flow well and subsequently harden.

The method described in the figures for producing a preform which is used in the production of a plate-shaped high-pressure molded body can, with corresponding modifications, also be used directly for producing high-pressure molded bodies. be used. This is achieved, for example, by pressing pressure in the belt press 20 e.g. to 25 50 bar and the pressing temperature increased to 150 ° C and the dwell time of the layer structure e.g. extended to 10 minutes, so that the binder contained in the layer initially flows well and then hardens. A raw plate is then removed from the belt press 20, the z. B. is cooled in a 30 downstream, cooled belt press to 30 ° C. The raw plate is then cut to length and decoratively painted for further use in a known manner.

Commercial usability Such decorative high-pressure molded articles of greater strength (e.g.

35 6 and 15 mm thick) are suitable, for example, for the manufacture of self-supporting components or as weatherproof panels for outdoor use.

Claims

Claims:

1. Process for the production of a synthetic resin printing form body, in which in one impregnation step fiber materials, such as wood fibers in the form of a bed (10), are applied to a conveyor belt (12) for the continuous production of a pre-compact or a raw plate and then optionally with both sides the Trenn¬ papers (25, 25 '). that have been coated with a binding agent consisting of a condensation resin or -harzgemisch based on phenols / or amino compounds and, and aldehyde such as formaldehyde ^{unilaterally'} are to be laminated, and in which the thus formed Layer structure (19) is continuously compressed to an average weight per unit area in the range between 900 and 1200 kg / m ³ and heated to a higher temperature at which the viscosity of the binder is reduced, so that the binder is completely in the pore volume of the compressed Mated fiber mass penetrates and possibly go out in the sequence is hardened, characterized in that the loose fiber materials are intimately mixed with the binder in a pre-impregnation step, for example in the blowline (3), the surface of the loose fiber materials being coated regularly with the binder, and in that these pre-impregnated fiber materials are dried in a hot air stream (6) to a residual moisture of at most 6% and that these dried, pre-impregnated fiber materials are then used in the impregnation step.

2. The method according to claim 1, characterized in that in the pre-impregnation step the binder is a solid, water-soluble. Flame retardant, which is dispersed in the binder, is added.

3. The method according to claim 2, characterized in that the flame retardant consists essentially of a water-insoluble nitrogen compound.

5 4. The method according to claim 2, characterized in that _t the flame retardant consists essentially of a water-insoluble nitrogen-phosphorus compound.

5. The method according to any one of claims 2 to 4, characterized in that the flame retardant borates are added.

6. The method according to any one of claims 2 to 5, characterized in that the flame retardant applied

15 amount 5 - 20% by weight based on the dry fiber material.

7. The method according to any one of claims 1 to 6, characterized gekenn¬ characterized in that additional fiber for the impregnation step

20 materials in loose form and / or in the form of fabrics, scrims, mats, nonwovens or the like can be added.

8. The method according to claim 7, characterized in that the additionally admixed fiber materials made of glass fibers

25 exist.

9. The method according to claim 7, characterized in that the additionally admixed fiber materials consist of natural fibers.

30

10. The method according to claim 7, characterized in that the additionally admixed fiber materials consist of synthetic fibers.

35 11. The method according to any one of claims 1 - 10, characterized in that a solvent-free condensation resin or resin mixture in liquid form is used as a binder. is used, which contains a solid resin content of more than 80% by weight and a water content of at most 8% by weight, preferably at most 6% by weight.

12. The method according to any one of claims 1-11, characterized gekenn¬ characterized in that the resin application in the pre-impregnation step is between 10 and 15% solid resin based on the dry fiber material.