JPS6247451B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) This invention provides a foamed synthetic resin molded product having functions and appearance characteristics unique to wood materials, especially a low coefficient of thermal expansion.
Furthermore, 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, bending strength characteristics, and processing characteristics.

(Prior art) In the past, the reinforcement of this type of foamed synthetic resin molded products was usually planned by adding or mixing inorganic materials such as glass fiber or rock wool. In order to maintain low molding costs, recent advances in foamed polyvinyl chloride, foamed polyethylene,
Attempts have been made to strengthen resin molded articles by mixing wood powder or similar cellulose materials into foamed resin materials such as foamed acrylonitrile-butadiene-styrene.

(Problems to be Solved by the Invention) Mixing the required amount of wood powder into such a molding resin increases the strength of the resin molded product, especially the bending strength, to approximately double that of a non-mixed resin molded product, In addition, the strain rate during and after resin molding is extremely low, and wear resistance is particularly improved, which is particularly meaningful in providing ideal and inexpensive reinforced resin molded products.

However, in such conventional molded products, there is a certain limit to the amount of wood flour mixed in as an aggregate, and the molding properties and heat insulation properties are not as good as the color tone or mass feeling that is closer to that of wood. In terms of processing characteristics, etc., it cannot overcome the characteristics peculiar to resin materials, and it also has disadvantages such as generating a large amount of toxic gas when heated and burned.

In addition, in the conventional method, it was usually
As shown in the above issue, extrusion molding or injection molding is used as a molding method, and the mixed wood powder itself extremely inhibits the fluidity of the molding resin material and also causes damage to the inner wall surface of the cylinder of the molding machine or the screw thread. This significantly increases the frictional resistance against the sliding surfaces, which requires a larger molding machine and particularly reduces the amount of molding per unit time.

This also causes wear and tear, particularly on the inside of the molding machine, reducing the service life of the molding machine, as well as creating excessive internal pressure on the die or mold surface, which can lead to breakage and wear of the die or damage and wear of the inside of the mold. At the same time, this also induced 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. during hot molding, and this generated wood acid significantly reduces the usage frequency of the molding machine cylinder, screw, die, mold inner surface, etc. This caused roughness on the surface of the product.

In order to neutralize such wood acid, the conventional method was to add an antioxidant to the resin material mixed with wood flour as shown in JP-A No. 52-37953. Therefore, the amount of antioxidant added must be adjusted depending on the amount of wood powder mixed in and the type of wood used, and the antioxidant and the process of mixing it are required. This resulted in higher costs for molded products.

Furthermore, in the conventional method, a large amount of steam is induced by mixed wood powder, etc., which adheres to the mold surface, causing problems 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.

(Means for Solving the Problems) In view of the inconveniences in the prior art, the reinforced foamed resin molded product according to the present invention heats and dries the wood powder itself to be mixed in, so that the wood powder contained in the wood powder is heated and dried. It dissociates and volatilizes wood acids, mainly acetic acid, and reduces the water content in the wood powder to about 3 to 8%, and also reduces the particle size of the wood powder used to 50 to 80%.
It was set at 150 meters.

By taking such special consideration, we eliminate the possibility of wood acid gas generation and water vapor generation during molding, eliminate the risk of wear and tear on the molding machine, especially severe wear, and corrosion, and also ensure a good surface. This provides a molded product with specific characteristics, and at the same time, the particle size is fine to improve compatibility with the mixed resin material.

In addition, it limits the amount of resin material to be mixed,
By using wood powder as the basic aggregate and creating foam voids as much as possible between the aggregates, it is said that the insulation and sound insulation properties are particularly good compared to conventional molded boards, and the mixed resin material is covered with the wood powder. It has a so-called honeycomb-like structure that connects while wrapping, and this makes the formed plate material have good mechanical properties such as bending strength and impact strength.

In addition, due to this structure, the properties of the molded board are said to be more similar to those of wood, and it can almost be treated as wood in terms of color tone, mass feel, and processing such as cutting or nailing. . In particular, in addition to these properties, the fragility of wood materials has been eliminated in terms of heat insulation properties and water resistance properties.

(Example) An example of a typical method for molding a wood-like foamed resin molded product according to the present invention will be described below.
Mix 15-30%, ideally 20% of a solvent such as toluene or aluma oil into a resin material such as vinyl chloride, and mix 15-30% of this resin material, ideally 20% with 60% dry wood powder. ~80%, ideally 80% and blowing agent 2-4
%, ideally 4%, knead and heat to 150-180℃
It is heated and foam-molded using a hot press or the like.

The wood powder used here is as fine a powder as possible, selected appropriately within the range of 50 to 150 mesh, and has been sufficiently heated and dried to have a moisture content as low as usual. 3-8%
This was taken into consideration to keep it within the range of .

When this wood flour is heated and dried, acetic acid, etc. normally contained in the wood flour reacts with the H ₂ O group in the wood flour, dissociates and evaporates, resulting in a decrease in the moisture content in the wood flour. At the same time, the dissociation and volatilization of residual wood acid are suppressed. By using wood flour under such unique drying conditions as an aggregate, it was possible to achieve specific effects on the various properties mentioned above.

It is also planned that the wood powder used will be used as is, along with regular wood cutting powder or abrasive powder, as well as particle board sanding powder. This is intended to save all costs required for processing sanding powder.

Even when the wood flour heated and dried in the above process is mixed into a resin material such as vinyl chloride and heated and molded, there is no risk of inducing new acid gas or producing water vapor, and it can be used as a regular pellet. It is said that it is possible to treat it in the same way as the above.

The solvents and foaming agents used in the above are selected according to the type of resin material used, and solvents such as methyl alcohol, acetone, benzene, trichlene, formic acid, or tetrahydrofuran are used for foaming. It is planned to use azobisisobutyronitrile, soda carbonate, freon, propane, butane or pentane as the agent.

The wood powder thus provided is used as aggregate 1, and by heating and foaming this aggregate 1 with a foamed synthetic resin material such as foamed vinyl chloride, foamed polystyrene, foamed ABS resin, etc. mixed with a solvent, aggregates 1~ 1
Foamed voids 3 are formed between the particles of the aggregate 1.
1 to 1 are each wrapped with a film 2 made of a resin material and connected as a single unit, as if the aggregate 1 and
The voids 3 are connected with the membrane 2 in a honeycomb manner.

In particular, in such a structure, while the aggregates are in contact with each other, complete foamed voids 3 are formed between the adjacent aggregates, and these are covered with a honeycomb-like coating 2. By linking them together, specific effects on the above-mentioned properties can be expected.

That is, since the aggregates 1 to 1 are configured so that they are in contact with each other, fragility in load-bearing strength is avoided, and the honeycomb-like structure characteristic of the coating 2 improves bending strength and impact resistance. , shape retention strength, etc. are dramatically improved, and the amount of resin material used is reduced, resulting in inconveniences as a resin board, including the occurrence of molding distortion, the generation of harmful gases during baking, and the occurrence of cracks during nailing. The aim is to eliminate the possibility of such occurrences and to improve the heat insulation properties over that of wood materials.

In addition, since the aggregate 1 is entirely encapsulated with the film 2, it has water resistance and water resistance even though it is a wood-like material.
It is said to have particularly good chemical resistance properties, and is expected to exhibit properties not normally found in wood materials.
It is possible to perform processing such as nailing.

In addition, although the main raw material of the material is wood flour as an aggregate, the presence of the resin film 2 makes it possible to not only mold, but also heat dry, heat weld, and other molding or processing treatments similar to those for resin plates. It was made possible.

(Effects of the Invention) The wood-like foamed resin molded product according to the present invention is provided as having the characteristic structure, action, and effect described above, and can achieve the above characteristics by using the same molding method as in ordinary resin molding. In particular, it has made it possible to provide a molded product having a low coefficient of thermal expansion and a good molded product that has little distortion due to changes in composition during and after molding.

In addition, the bending strength as a mechanical property is strong, and of course the hardness is also sufficient, and the surface abrasion resistance is significantly improved.

Furthermore, in terms of materials, wood is used as the main raw material and resin is used as a mere coating 2, making it possible to process with ordinary woodworking machines and tools, and also perfect surface treatment with lacquer, paint, etc. ,
At the same time, the mixed wood flour ensures that the molded product has the unique color tone and feel of wood.

In particular, as a woodworking material, the entire cut surface exhibits wood-like characteristics, and unlike conventional wood-like materials made by spraying, molding, or pasting with decorative sheets, there is no hint that it is a synthetic resin material. It was effective.

[Brief explanation of the drawing]

The attached drawing is an enlarged sectional view of the main part of the wood-like foamed resin molded product according to the present invention. In the figure, 1...aggregate, 2...film, and 3...voids are shown.

Claims (1)

[Claims] 1. 15-30% of a synthetic resin material such as vinyl chloride to which 15-30% of a solvent such as toluene has been added, and 60-80% of wood powder that has been heated and dried to promote the dissociation and volatilization of the wood acid contained therein. A wood-like foamed resin molded product characterized by mixing and kneading 2 to 4% of a foaming agent and heat foaming.