JPH047283B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding a composite board containing a large amount of wood flour as a molding aggregate, and particularly to a molding method adapted to the characteristics of the mixed wood flour.

Therefore, when molding a resin material that contains a large amount of mixed materials, it is necessary to clearly recognize the molding characteristics of the resin itself, as well as the effects of the mixed materials during molding, and respond immediately. It is particularly important to selectively use molding techniques that The problem with the mixing of such different materials is that the mixed materials, such as wood powder, have a lot of frictional resistance during flow, and are not compatible with the resin material, and furthermore, they can cause moisture or wood acid gas to enter the molding machine. This is particularly problematic when large amounts occur, and special ingenuity is required in the molding method.

The present invention combines the advantages of wood materials and composite resin materials in order to effectively eliminate the disadvantages of wood molded products and synthetic resin molded products in recent years, and to meet the strong demand for new materials. This is an attempt to provide a composite plate molded product that is inexpensive and has high utility value.

In particular, in the present invention, wood flour, which is a dissimilar material incorporated into the resin material, is subjected to various processing so that the characteristics of the mixed wood flour are matched under certain conditions, and open mold extrusion is performed during molding. By preparing a device and a hot roll device, it eliminates the extrusion friction resistance peculiar to mixed wood powder during molding and effectively removes generated gas, etc., making it especially possible to provide mass production of wood composite boards. This is what I did.

In addition, in the present invention, since the extruded dough to be formed is first made into a plate shape with a predetermined thickness in a hot roll device, the composite board to be formed is warped and has some problems before being expanded or contracted. No defects were observed during the process, making it possible to provide wood composite boards with the desired thickness and flatness.

The method for forming a wood composite board according to the present invention has a particle size of 80 to 300 mesh and a moisture content of 1 to 5%, in order to obtain various effects on the properties described above. 30～
70% of the mixture is heated and extruded with a kneading screw onto the front of a hot forming roll, and the extruded dough is heated and rolled to a predetermined thickness using the hot roll. Based on this point, the following specific embodiments and considerable design changes accompanying these embodiments are planned.

Hereinafter, a typical method for forming a wood composite board according to the present invention will be explained. 1 is wood powder obtained by heating and crushing wood, and its particle size is 80 to 300.
It is made into a mesh with a water content of 1 to 5%, and is usually prepared as pure wood flour, or after adding urea resin adhesive 2 to wood chips etc. and curing with heat. It was planned to crush this to obtain similar wood powder 1'.

The particle size and water content of the wood powder are specified for the following reasons during resin molding. In other words, when the wood flour as an aggregate has a moisture content within the usual range, when the wood flour is charged into a molding machine together with resin and heated, a larger amount of water vapor and wood acid gas is produced than the mixed wood flour. This causes corrosion of the inner wall surface of the molding machine, wear and tear of the die, mold, etc., and also causes problems such as roughening of the surface of the molded product itself, and the formation of bubbles and cavities.

In order to avoid such inconveniences, the wood flour is subjected to sufficient heat treatment during molding to volatilize as much of the wood acid contained therein as possible, and at the same time, during resin molding, the wood acid evaporates as it gasifies. The moisture content has been removed to prevent this from occurring.

The use of the urea-based resin adhesive 2 in the description above creates a hardened layer of the adhesive 2 on the surface of the wood flour 1 to be molded, and the moisture dissipated during the heat effect treatment is absorbed into the molded wood flour again. This prevents it from being infiltrated by wood, neutralizes wood acid during heat curing, and provides the necessary lubricity to the molded wood powder after curing.

The problem with the slipperiness of wood flour has mainly been related to good kneading during mixing of the materials, compatibility of the materials with each other during molding, and extrusion resistance during molding. By specifically setting the particle size of the mixed wood flour 1 to 80 to 300 mesh, these problems can be avoided.

A thermoplastic synthetic resin material 3 such as vinyl chloride resin is prepared for the wood flour 1 and 1' having the above structure,
This was mixed with wood flour 1 in a range of 30 to 70%, and a suitable stabilizer was added thereto, followed by resin molding according to the following method.

One of the forming methods is to put the mixed material into the hopper 12 of an extrusion device a having horizontal twin screws 11, 11, heat and knead it, and then press it from the device a. At the same time, the extruded dough m is held by a guide 13 and guided sequentially to forming hot rolls 14, 14, and rolled and formed into a wood composite board having a predetermined thickness.

In the embodiment shown in FIG. 1, a cylinder 15 having one or two screws 11 is used to heat and knead the dough m. The raw material 3 in the form of powder or pellets is directly introduced into the cylinder 15 where it is melted and kneaded.

Next, in the embodiment shown in FIG. 2, in forming such an extruded dough m, wood flour 1 and material 3 are
After thoroughly mixing in the blender 16,
This is mixed with a kneading device 1 such as a pressurized kneader or Banbury.
Knead the dough using hopper 1.
8 is guided to an extrusion device a' of a cylinder 19 using a two-axis taper screw (not shown), and is extruded using a horizontal uniaxial or biaxial screw 20.

In such devices a and a', the molding die is omitted and a simple extrusion opening is used, and this opening is
A guide 13 is provided in this opening.

The guide 13 communicates between the openings of the devices a and a' and the roll 14, and the guide 13 connects the openings of the devices a and a' with the roll 14.
and a side plate 13b, and each plate 13 is sufficiently heated using an electric heater 21 or other appropriate method, and an infrared heater 22 is disposed above the guide 13 to cool the extruded dough m. It is designed to reliably prevent

The thermal insulation heating during the process of reaching the forming roll 14 is due to the fact that a large amount of wood flour 1, which is a different material, is included in the resin material as a forming aggregate, and the dough m is sufficiently heated. If proper heat storage conditions are missing, the peripheral portion of the extruded dough will harden rapidly, and only the central portion will be significantly drawn into the rolls 14, making roll forming difficult and causing wrinkles in the formed dough. In addition, it causes irregularities in the structure of the molded product, causing deformations such as warping and distortion. In order to avoid such inconveniences in shaping, the dough m extruded from devices a and a' is sufficiently kept warm and heated by guides 13 so that it can be accurately shaped by rolls 14. This is what I did.

The dough m thus extruded is transferred to the roll 14,1
In step 4, the plate is sufficiently compacted and rolled into a plate shape, and then a correction roll 23 is used to correct the density of the structure during rolling, thereby preventing the occurrence of warpage in the formed plate. In addition, the rolls 24-24 are used to correct warping and bending that have already occurred in the molded plate.

The molded plate m' provided in the above is laminated with a film 26 by a laminating device 25 as necessary, and then cooled and kept as appropriate with cooling rolls 27 to 27, followed by roll slitting. Tar 2
After being cut in the flow direction by 8,
The plate material is cut to a specified size using a cutter 29 to form a molded plate material of the specified size.

In addition to providing plates with such fixed dimensions, when adding patterns, shapes, etc. to these plates, the supplied fixed-sized plates are sufficiently heated using a hot press device 30, and then heated using a cold press device 31. It was separately planned to perform mold cooling.

The method for forming a wood composite board according to the present invention is expected to achieve specific effects on the above-mentioned properties due to the characteristic structure described above. If a large amount of wood flour is mixed in, the extrusion device will be strained, resulting in the inability to extrude, wear of the extrusion screw, or damage to the molding die. Therefore, it was necessary to reduce the extrusion pressure as much as possible and perform a gentle extrusion operation, but such a method is not only unsuitable for mass production molding, but also requires cooling the dough before molding, resulting in poor finish. This is due to variations in product quality. The present invention has been specifically disclosed to avoid such inconveniences, and by extruding the forming dough from a cylinder in front of the forming rolls without passing through a die, the extrusion resistance in the extrusion device is reduced as much as possible. This eliminates the possibility of wear and tear on the equipment, breakage of the die, etc., and at the same time enables mass production molding by reliable extrusion in large quantities. Furthermore, there is no problem of cooling the extruded dough m, and variations in quality in the formed plate materials are also eliminated.

Furthermore, in the present invention, in forming the plate material, since the plate material is roll-formed to a predetermined width from the beginning of the forming process, the formed plate material has problems such as warping and distortion. First, the company promises to provide high-quality board or panel materials.

Next, by using roll forming, the surface of the plate material was not only glossy, which could not be seen in extrusion molding, but also the smoothness and density of the surface of the plate material were particularly good.

In addition, water vapor, wood acid gas, etc. generated inside the cylinder are led out of the cylinder along with the fabric m, which not only prevents wear and tear on the cylinder and screws, but also eliminates problems such as bubbles and nests in molded products. It is what was done.

The present invention is equipped with sufficient heating and kneading by a cylinder and a roll device suitable for forming large plates, thereby expanding a new dimension to the forming of wood composite boards, which are particularly difficult to form.

[Brief explanation of drawings]

Fig. 1 is a side view of the main part showing one embodiment of the molding method according to the present invention, Fig. 2 is a side view of the main part showing another embodiment, and Fig. 3 is a plane sectional view of the main part of the extrusion part. ,
FIG. 4 is a longitudinal sectional view of the same essential parts, FIGS. 5A and 5B are broken end views of the wood powder, and FIG. 6 is an enlarged sectional view of the composite board. In addition, in the figure 1...wood flour, 2...adhesive, 3...synthetic resin material, 11...screw, 12...hopper, 13
...Guide, 14...Forming heat roll, 15...Cylinder, 16...Blender, 17...Kneading device, 18...
Hopper, 19... Cylinder, 20... Screw, 21... Electric heater, 22... Infrared heater, 23... Correction roll, 24... Roll, 25... Laminating device, 26... Film, 27... Cooling roll, 28... Roll slitter, 29 …Cutter,
30 shows a hot press device, 31 shows a cold press device.

Claims (1)

[Claims] 1. Particle size is 80 to 300 mesh, and moisture content is 1 to 5.
% of wood flour is mixed into a thermoplastic resin material, heated, and extruded with a kneading screw onto the front of the hot molding roll, while heating the extruded dough. 1. A method for forming a wood composite board, characterized in that it is rolled to a predetermined thickness using hot rolls. 2. The method for forming a wood composite board according to claim 1, wherein the screw is a biaxial screw. 3. The extruded dough is heated by using the receiving bottom plate and both side plates of the extruded dough as heating plates, and by installing an infrared heater above the extruded dough. A method for forming the wood composite board.