JPS6143504A - Ligneous synthetic plate - Google Patents

Abstract

PURPOSE:To prevent a warp of a molded plate by removing residual stress, by a method wherein after a thermoplastic resin molding material having a neutralized cellulose series pulverized aggregate has been heated and cooled residual inner stress is removed by sanding of a resin-cured layer of the surface of the molding material. CONSTITUTION:An aggregate (a) is an article to be obtained by a method wherein wood uinegar in a cellulose material is neutralized and room generating wood uinegar gas at the time of resin molding after that is eliminated and a ligneous synthetic plate A is obtained by performing the resin molding by mixing an appropriate quantity of the aggregate (a) with a thermoplastic resin material (b). The synthetic plate A is so constituted that it is cured after it has been heated and amount corresponding to the surface (x) of the synthetic plate A is removed by sanding treatment so that a (y) part is exposed directly as the external surface. With this construction, inner residual stress in the ligneous synthetic plate A' is removed and generation of a warp and twist in the synthetic plate A' are prevented effectively.

Description

Detailed Description of the Invention (Industrial Field of Application) This invention is aimed at reducing internal residual stress in thermoplastic synthetic resin moldings containing wood flour, rice husk flour, bakasu flour, and other cellulose-based fine aggregates. The present invention is concerned with the provision of wood composite boards that are free from molding distortion and can be used for various purposes by eliminating the occurrence of distortion in resin molded products.

(Prior art) In general, synthetic resin molded products have variations in the composition of the molded product, such as density and density, due to the relationship with the materials used and the molding conditions, and residual internal stress due to the molding conditions during molding. It is something that The problem of residual internal stress is that problems such as warpage and twisting occur in the molded product during cooling shrinkage after molding, shrinkage over time, or expansion and contraction due to temperature changes.

As a means to prevent warping, twisting, etc. in molded products that warp, attempts have been made to mix various aggregates into resin molded products.1. They have been found to have considerable effects depending on their purpose of use.

However, if the resin molded product is a plate material, etc.
It is difficult to correct the distortion of the molded product due to the mixing of aggregate, which often causes problems such as warping and twisting.

(Problem to be Solved) In the present invention, with the intention of preventing the distortion of resin moldings in the past, a large amount of aggregate is mixed into the resin moldings, and then this cellulose is mixed with a large amount of aggregate. It is intended to remove residual internal stress in resin molded products containing a large amount of aggregate.

In other words, if a large amount of cellulose aggregate is mixed into a resin molded product, this mixed aggregate will extremely inhibit the fluidity of the molded resin, and as a result, it will cause more residual stress than expected in the resin molded product. This is what happened.

If the resulting internal residual stress is left undisturbed, the molded product will become distorted in the direction of the stress, resulting in many inconveniences in use.

Such residual internal stress is caused even more by the fact that the direction of the residual stress is not necessarily constant because the flowability of the molding resin is inhibited due to the mixing of cellulose aggregate, which causes pulsations in the molding resin. This caused inconvenience.

In addition, the problem of residual internal stress becomes even more noticeable when the resin molding is subjected to secondary processing, and when the resin molding is reprocessed by hot pressing, etc. , the product warped and twisted more than expected.

The wood composite board according to the present invention eliminates residual stress in such resin molded products, especially resin molded boards with a large amount of cellulose aggregate, and can be used as is or further reprocessed for automobiles. This is to prevent distortion of the molded plate during use.

(Means for Solving the Problem) In order to eliminate such residual internal stress, the wood composite board according to the present invention is particularly suitable for thermoplastic resin molded materials having neutralized cellulose-based fine powder aggregate. After heating and cooling the thermoplastic resin molded material, residual internal stress in the heated and cooled thermoplastic resin molded material shall be removed by sanding the hardened resin layer on the surface of the thermoplastic resin molded material, thereby causing internal stress to be removed. This provides a wood composite board that does not retain stress.

As a result, not only can the formed wood composite board be used as is, but even if it is molded using a hot press, the reprocessed product will not warp or twist, ensuring good use. It is something.

(Embodiment) A typical embodiment of the present invention will be described below with reference to the accompanying drawings.

First, the aggregate a to be mixed in the forming of the wood composite board is a cellulosic material such as wood chips, pulp, bakasu, or rice husks with an air-dried moisture content within the moisture content of the material. After measuring the weakening of the structure, a urea-based resin solution is applied and impregnated into this structure, and then heated, dried, and crushed in a temperature range of 100 to 200°C. .

During the impregnation and heating pulverization of the urea-based resin liquid, the wood acid in the material is neutralized, eliminating the possibility of wood acid gas being generated during subsequent resin molding. Furthermore, by impregnating, impregnating, hardening and crushing the urea-based resin liquid, each aggregate a has a hardened urea-based resin material portion, which prevents the inconvenience of re-absorption of moisture in the cellulosic material and improves the bone structure. This material is made by adding appropriate lubricity to material a.

Next, as another method for forming aggregate a, a treatment liquid that absorbs and discharges acidic gases such as monoethanolamine and triethanolamine as the temperature changes is applied to the cellulose material, which is then heated and crushed. As a result, neutralized fine aggregate was obtained separately.

It is necessary to specifically prepare the aggregate a for molding in the following, by removing the wood acid gas generated from the cellulose aggregate a mixed in with the resin molding machine in the following resin molding. The purpose of this is to prevent damage to the resin and achieve smooth resin molding.

That is, in resin molding, when cellulose aggregate a is mixed into a resin material and then heated and molded, more wood acid gas and water vapor are generated than the mixed aggregate a, and this wood acid gas In addition, the water vapor caused various adverse effects on the molding machine and the product. In particular, the wood acid gas and water vapor generated corrode and damage the cylinder, cylinder guide, cylinder screw, etc. of the molding machine, and also cause bubbles and rough surfaces of the product.

In addition, since the aggregate to be mixed has been pre-cured with a urea-based resin liquid, it is said that the mixed aggregate has good lubricity and mixes well with the resin material. Not only that, but also there is little frictional resistance with the molding surface of the molding machine during molding, making it possible to perform good extrusion or injection.

A suitable amount of aggregate A thus provided was mixed into thermoplastic resin material in consideration of the intended molded product and molding method, and resin molding was performed to obtain wood composite board A. .

In addition, in this resin molding, it is planned to provide wood composite board A using various methods similar to the molding of general molded boards, such as adding a foaming agent or a coloring agent to this resin material. be.

The wood composite board A thus formed was heated in a temperature range of 140 to 300°C and then cured for 5 to 6 hours in a temperature range of around 100°C to first remove the initial shrinkage distortion. This is what I did. The quenching of the resin is carried out in advance to remove distortions caused by the residual stress existing inside the wood composite board A, the density of the structure, etc.

In this way, shrinkage distortion, etc. are minimized, and the wood composite board is prevented from warping or twisting due to subsequent resin molding or shrinkage over time.

A portion corresponding to surface X of the wood composite board A, which is a resin molded product that has been quenched in this way, is removed by sanding,
The y portion is directly exposed as the outer surface.

As is clear from the illustrated example, the deletion of the portion X of the exposed surface is intended to delete the portion where the resin material is dense. That is, in resin molding with aggregate a mixed in, the resin in the aggregate a oozes out onto the surface of the molded product, creating a cloth portion of the resin material on this surface.

In addition, the dense portion of the resin material that is exposed to heat is considered to be a portion where internal stress is particularly left due to the difference between the density or the flow direction due to the pulsation of the resin material during molding and the direction perpendicular to the flow. It is something that

Therefore, the sanding and removal of this surface part X is particularly meaningful, and when this surface part X is removed from wood composite board A that has sufficiently corrected the distortion, the internal residual stress is almost completely eliminated. .

Thus, the wood composite board A from which the surface portion X has been removed is molded by hot pressing and cold pressing, and the decorative boards, doors, and other moldings are provided as the wood composite board A'.

(Effects) The wood composite board according to the present invention is expected to have the following effects due to the characteristic structure described above. That is, (1) The internal residual stress in the formed wood composite board A' was removed, and the warping and twisting of the composite board A' was effectively prevented.

(2) Shrinkage distortion in the wood composite board A° was prevented, and the composite board was prevented from warping and twisting due to shrinkage.

(3) Aggregate a such as wood flour is exposed on the surface of the wood composite board A', giving it the feel of wood, and its slight moisture absorption function prevents sweating or perspiration on the contact surface. Ta.

(4) Since the aggregate a was exposed on the surface of the wood composite board A°, it was said that the abrasion resistance was good and a suitable contact resistance was provided.

(5) Since the aggregate a was exposed on the surface of the wooden composite board, it was found that printing ink, paint, etc. had good adhesion when sprayed.

(8) Aggregate a was exposed on the surface of the wood composite board A°, and there was no warpage or twisting, indicating that the adhesiveness was good.

[Brief explanation of drawings]

Fig. 1 is an enlarged cross-sectional view of the main part of the wooden stand/molded plate A according to the present invention, Fig. 2 is an enlarged cross-sectional view of the same with the surface portion removed, and Fig. 3 is a perspective view of the molded product. . In Figure 1, a indicates aggregate, and b indicates resin material.

Claims (4)

[Claims] (1) After heating and cooling a thermoplastic resin molded material having a neutralized cellulose-based fine aggregate, residual internal stress in the heated and cooled thermoplastic resin molded material is removed by sanding the hardened resin layer on the surface of the thermoplastic resin molded material. (2) The wood composite board according to claim 1, wherein the aggregate has an average particle size of 100 mesh or more and a water content of 3 cm or less. (3) The wood composite board according to claim 1, wherein the neutralization is performed by impregnating a urea resin and heating. (4) The wood composite board according to claim 1, wherein the neutralization is performed by impregnating and heating a treatment liquid having a function of absorbing and discharging acidic gases such as monoethanolamine and triethanolamine. .