JPH021176B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a foamed synthetic resin molded product having the functions and appearance characteristics unique to wood materials, especially having a low coefficient of thermal expansion.
Moreover, the present invention relates to the provision of a resin molded product that is free from distortion during or after molding and has excellent wear resistance and bending strength characteristics.

Previously, this kind of reinforced foamed synthetic resin molded products were mixed with inorganic materials such as glass fiber and rock wool.
In order to bring a more natural feel to resin molded products and to maintain low molding costs, wood has recently been incorporated into foamed resin materials such as foamed polyvinyl chloride, foamed polyethylene, and foamed acrylonitrile-butadiene-styrene. Various attempts have been made to incorporate flour or similar cellulosic materials.

Mixing the required amount of wood powder into such a molding resin increases the strength of the resin molded product, especially the bending strength, approximately twice that of a non-mixed resin molded product, and also increases the strength during resin molding and after molding. It has a significantly low strain rate and particularly improved wear resistance, and is particularly meaningful in providing an ideal and inexpensive reinforced resin molded product.

However, despite these excellent properties of the molded product, the inherent properties of the wood flour material contained in the product significantly diminished the molding properties of the resin, resulting in a relatively expensive product.

That is, when wood powder is mixed in, the mixed wood powder itself extremely inhibits the fluidity of the molded resin material, and also significantly increases the frictional resistance against the inner wall surface of the molding machine cylinder or the sliding surface of the screw, etc. In addition to requiring a molding machine, the moldability per unit time is particularly reduced.

This also causes particular wear and tear on the inside of the molding machine, reducing the service life of the molding machine, as well as creating unnecessarily high internal pressure on the die or mold surface, causing breakage and wear of the die or damage and wear of the inside of the mold. At the same time, this caused surface roughness of the molded product itself.

In addition, in the conventional case, mixed wood powder generates a large amount of wood acid, especially acetic acid, etc. after hot molding, and this wood acid induces corrosion of the molding machine cylinder, screw, die, mold inner surface, etc. However, this significantly reduced the frequency of use of molding machines, molds, etc., and also caused roughening of the surface of the molded product.

In addition, in the conventional method, a large amount of steam was induced by the mixed wood powder, etc., which adhered to the mold surface, causing the problem of surface roughness of the molded product and deterioration of the strength of the molded product.

Furthermore, in such conventional methods, the mixed wood powder and the resin material did not become completely integrated, creating voids, air bubbles, etc. around the mixed wood powder, which significantly reduced the strength of the molded product. It is something.

The reinforced resin molded product according to the present invention has been specially devised in view of the inconveniences in the prior art, and the wood powder to be mixed is made into wood chips, etc., and the wood chips are mixed in advance with a thermosetting resin adhesive. After heating and curing the adhesive, it is cut or crushed into powder or chunks to volatilize the generated wood acid, and at the same time, most of the frictional resistance unique to wood powder is absorbed into the molding resin material itself. This method also eliminates the generation of water vapor gas during molding, eliminates the disadvantages of the prior art described above, and provides a wood-like foamed resin molded product with excellent properties such as bending strength at a low price.

Hereinafter, a typical example of the reinforced foamed resin molded product according to the present invention will be explained in detail.A thermosetting resin material is kneaded into wood chips or wood flour as an adhesive material, and then heated by a hot press method or the like. It is made by pressing and bonding into plates, blocks, sticks, etc., and first, wood acids such as acetic acid produced when wood flour or wood chips are heated are gasified and evaporated.

Wood chips, wood flour, etc. as the main component from which wood acid has been removed, such as boards, bars, or lumps, are simultaneously reduced in water content by 1 to 1% through the hot pressing process.
It is made into a neutral and extremely dry aggregate by cutting, crushing, or other means to create mixed aggregate with an appropriate particle size.

Wood chips made of such crushed aggregate have a resin material impregnated and hardened in the wood composition, so the frictional resistance of the crushed surface shows a resistance value similar to that of chips made of molded resin material. be.

This makes it possible to provide molded products of almost the same size using a normal molding machine without requiring more extrusion or injection pressure than necessary during molding. This eliminates the risk of wear and tear on the molding machine cylinder, screw, die, mold, etc. caused by the generation of internal pressure.

That is, the aggregate provided in the above is heat-cured with a thermosetting resin material in the previous pretreatment to remove the wood acid in the wood powder, and at the same time, The water content has been reduced to about 1 to 5%.

In addition, the thermosetting resin suppresses the hygroscopicity of the aggregate, which is said to be extremely dry, and suppresses the generation of acid gas and water vapor during molding as much as possible.
The molding properties, particularly the strength and surface properties of the molded product, are particularly improved, and wear and tear on the mold itself is particularly reduced.

Furthermore, the aggregate mentioned above has low frictional resistance itself and can be particularly molded by handling in the same way as general aggregate.

The aggregate thus provided is mixed into a foamed synthetic resin material such as foamed vinyl chloride, foamed polystyrene, foamed ABS resin, etc. at a rate of 5 to 30% and heated to 150 to 180 degrees.
It is molded by foaming injection or extrusion within the temperature range of 30 to 30 degrees.

With this molding method, there was no problem of poor compatibility between mixed wood powder and foamed resin material, and it was possible to provide the desired molded product. .

The foaming agents used in the above are selected as appropriate depending on the molding characteristics of the desired resin material, the degree of foaming, etc., and are generally azobisisobutyronitrile, Possible blowing agents include azobisformamide, barium azobisformate, azodicarbonamide, diazoamide, ethyl diazoate, ethyl azobisate, and 4,4'-bisdiphenyl ether.

In addition, the foamed synthetic resin material mentioned in the description is separately priced at 5~
It was planned that 10% of calcium carbonate would be mixed in as an aggregate to add hardness to the molded product and improve its fire resistance. In addition, it was separately planned to use this calcium carbonate as a substitute for a pigment to impart a desired color tone to the molded product.

In addition, the preparation of the aggregate exemplified in the above is intended to create the aggregate specifically, but the abrasiveness that occurs when surface abrasive of normally manufactured and commercially available particle boards is used. Naturally, it was planned to use powder as the mixed aggregate, and the molding method and composition were the same as the mixed aggregate in the above example.

The use of such particle board abrasive powder promises to further reduce the molding cost for the aggregate molding in the above example. That is, particle boards that are pressure-formed using a hot press are usually subjected to single-sided or double-sided polishing, and the amount of abrasive powder generated is extremely large, and there are many difficulties in disposing of the generated abrasive powder. It is something.

The use of particleboard abrasive powder is
In this dual sense, the cost reduction of molded products has been beneficial.

In addition, the aggregate mentioned above is wood chips, wood flour, etc. that has been subjected to a series of pretreatment processes such as heating, pressing, and curing to reduce the moisture content to about 1 to 5%. The use of aggregate with such a low water content reduces the generation of water vapor during molding, prevents roughening of the molded surface, and also prevents the inclusion of various air bubbles.

The foamed reinforced resin molded product according to the present invention has the above-mentioned characteristic structure, which makes it possible to provide a molded product with the above characteristics using the same molding method as in ordinary resin molding. In particular, it is possible to provide a good molded product with a low coefficient of thermal expansion and with little distortion due to changes in composition during and after molding.

In addition, it has high bending strength as a mechanical property, and of course has sufficient hardness, and has significantly improved surface abrasion characteristics.

Furthermore, the inclusion of wood-based materials makes it possible to process them using ordinary woodworking machines and tools, and also makes it possible to perfect the surface treatment with lacquer, paint, etc., and at the same time, the wood-based mixture allows for the unique color tones of wood. , which promises a tactile feel in molded products.

In particular, as a woodworking material, the entire cut surface exhibits wood-like characteristics, and unlike the conventional wood-like materials made by spraying, molding, or pasting of decorative sheets, it is important to make it clear that it is a synthetic resin material. It has no effect.

Claims (1)

[Claims] 1. A thermosetting resin material is added to wood or similar cellulosic material, heat-pressed and cured to remove wood acid and moisture content, and
Reinforcement characterized by cutting or crushing this hardened wood material to obtain powdered or lumpy aggregate, mixing the aggregate into a thermoplastic resin material equivalent to 5 to 30%, and heating and foaming the aggregate. Foamed resin molded products. 2. The reinforced foamed resin molded product according to claim 1, characterized in that the moisture content in the aggregate is 1 to 5%.