JPH047681B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) This invention is directed to the removal of internal residual stress in thermoplastic synthetic resin moldings containing wood flour, rice husk flour, bakasu powder, and other cellulose-based fine aggregates. The purpose of this invention is to eliminate the occurrence of distortion in resin molded products and to provide a wood composite board free from molding distortion that is suitable for various purposes.

(Prior art) In general, synthetic resin molded products have variations in composition between coarse and dense parts 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 such residual internal stress is that it causes problems such as warping and twisting of the molded product during cooling shrinkage after molding, shrinkage over time, or expansion and contraction due to temperature changes.

As a means of preventing such molded products from warping or twisting, attempts have been made to mix various aggregates into resin molded products, and this has been found to be quite effective depending on the purpose of use. It is something that was given.

However, when the resin molded product is a plate material, etc., it is difficult to correct the distortion of the molded product due to the inclusion of such aggregate, and problems such as warping and twisting often occur. It is something that

(Problems to be Solved) In the present invention, with the intention of preventing distortion of the resin molded product in the past, a large amount of aggregate is mixed into the resin molded product, and then this It is intended to remove residual internal stress in resin molded products containing a large amount of cellulosic 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 such internal residual stress is left as is,
The molded product becomes distorted in the direction of the stress, causing 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. Warping out more than expected,
This is what caused things to get twisted.

The wood composite board according to the present invention eliminates residual stress in such resin molded products, especially resin molded boards containing a large amount of cellulose aggregate, and can be used as is or further reprocessed. 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 made of a thermoplastic resin molded material having neutralized cellulose-based fine powder aggregate. After heating and cooling the thermoplastic resin molding material,
The residual internal stress of the heated and cooled thermoplastic resin molding material is removed by sanding the resin hardening layer on the surface of the thermoplastic resin molding material, and as a result, the wood composite board with no internal stress remains. This is what was provided.

As a result, the shaped wood composite board can not only be used as is, but also when reprocessed by hot pressing, etc., there will be no warping or twisting, and it is guaranteed to be used in good condition. .

(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, bacchus, or rice husks with an air-dried moisture content within the moisture content of the material. After embrittling the structure, a urea-based resin liquid is applied and impregnated into the structure, and then heated, dried, and pulverized in a temperature range of 100 to 200°C.

During the impregnation and heating pulverization of the urea 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-based 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 into the resin molding in the resin molding machine described below. The purpose of this is to prevent damage to the resin and achieve smooth resin molding.

That is, in resin molding, cellulose aggregate a
When mixed into a resin material and heat-molded,
A large amount of wood acid gas and water vapor were generated from the mixed aggregate a, and this wood acid gas and water vapor had various adverse effects on the molding machine and the product. In particular, the generated wood acid gas and water vapor cause corrosion and damage to the cylinder, cylinder die, cylinder screw, etc. of the molding machine, and also cause air bubbles and roughness on the surface of the product.

In addition, since the mixed aggregate has been pre-hardened with a urea-based resin liquid, the mixed aggregate is said to have good lubricity and mix well with the resin material. Not only that, but also there is less frictional resistance with the molding surface of the molding machine during molding, resulting in good extrusion.
Or it is something that makes injection possible.

A suitable amount of the aggregate a thus provided is mixed into the thermoplastic resin material b in consideration of the intended molded product and the molding method to perform resin molding, resulting in a wood composite board A.
This is what I got.

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 is heated to 140 to 300℃.
After heating in a temperature range of 100° C., the material is cured for 5 to 6 hours in a temperature range of around 100° C. to first remove the initial shrinkage distortion. Such quenching of the resin is carried out in advance to remove distortions caused by 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.

The x portion of the surface of the wood composite board A, which is a resin molded product that has been hardened in this manner, is removed by sanding so that the y portion is directly exposed as the outer surface.

This deletion of the surface x portion is intended to delete the dense portion of the resin material b, as is clear in the illustrated example. That is, in resin molding in which aggregate a is mixed, resin b in aggregate a oozes out onto the surface of the molded product, creating a dense portion of resin material on this surface.

In addition, the dense parts of the resin material b are the parts 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.

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

Thus, the wood composite board A with the surface x portion removed
Molded by hot pressing and cold pressing to produce decorative boards, doors, and other molded wood composite boards.
A′ was provided.

(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' is removed, and the composite board A' begins to warp;
Twisting was effectively prevented.

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

(3) Aggregate a such as wood powder is exposed on the surface of the wood composite board A′, which gives it a wood-like feel, and its slight moisture absorption function prevents sweating or sweating 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 wood composite board A', it was found that the adhesion of printing ink, spray paint, etc. was good.

(6) Aggregate a was exposed on the surface of the wood composite board A′, and there was no warping or twisting, indicating that the adhesion was good.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a main part of a wood composite board A according to the present invention, FIG. 2 is an enlarged sectional view of the same with the surface portion removed, and FIG. 3 is a perspective view of a molded product. In the figure, a indicates an aggregate material, and b indicates a resin material.

Claims (1)

[Scope of Claims] 1. After heating and cooling the thermoplastic resin molding material having a neutralized cellulose-based fine aggregate, the heated and cooled thermoplastic resin molding material 1. A wood composite board, wherein residual internal stress is removed by sanding a 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 moisture content of 3°/wt or less. 3. The wood composite board according to claim 1, wherein the neutralization is performed by impregnating with a urea resin and heating. 4. The wood composite board according to claim 1, wherein the neutralization is carried out by applying and heating a treatment liquid having a function of absorbing and discharging acidic gases such as monoethanolamine and triethanolamine.