JP4171788B2 - Molded product manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a molded product obtained by molding a small piece of material using a thermoplastic resin and an isocyanate compound as a binder, and more specifically, a small material in which a dry thermoplastic resin (A) is attached to the surface. The present invention relates to a method for producing a molded product comprising a step of moistening a piece of material with an emulsion or an aqueous solution of a thermoplastic resin (B) before pressure molding in a pressure molded product bonded with an isocyanate compound.

In order to prevent the decline of forest resources, which plays an important role in the global environment, it is part of the wood that has been of no use other than incineration, as well as effective use of wood produced from forests. It is important to develop methods for using branches and leaves and bark.
Furthermore, the disposal of building waste materials such as wood and gypsum board that have recently been generated due to the dismantling of houses has become a major social problem.
One of the effective uses of these forest resources, building waste, etc. is a method in which the material is made into small pieces and used as a molded product such as a board through a binder. For example, a method for making a piece-like material into a board using a thermosetting resin such as urea formaldehyde resin or isocyanate compound as a binder is widely used.

  The board manufacturing method using this thermosetting resin needs to be cured under a high temperature condition higher than 100 ° C. Therefore, a heating device such as a hot press and a lot of energy are required. . Furthermore, when urea formaldehyde resin or the like is used, formaldehyde is contained in the binder, which is caused by the safety problem of workers due to formaldehyde generated during work and formaldehyde remaining in the manufactured board. Various problems are known. A new board that does not have such a problem has been desired. In addition, when manufacturing a thick molded product using a thermosetting resin, it takes a long time to fully cure to the inside, which further increases energy costs and tends to cause quality variations. There was also a point.

Therefore, the present inventors have obtained an excellent molded product obtained by further moistening water in a pressure molded product obtained by binding a dried mixture of a small piece material and a thermoplastic resin (A) with an isocyanate compound. Was found and obtained (Japanese Patent Application No. 2002-344902). As a result of various investigations thereafter, a new production method for improving the physical properties of the obtained molded product has been found.
Japanese Patent Application No. 2002-344902

  The present invention aims to further improve physical properties in the invention described in Japanese Patent Application No. 2002-344902 before publication, and solves a completely new problem.

The present invention
1) A step of mixing an emulsion of the thermoplastic resin (A) and a small piece of material,
2) A step of drying the obtained mixture to form a small piece material with the dried thermoplastic resin (A) attached to the surface,
3) a step of wetting the obtained piece-like material with an emulsion or an aqueous solution of the thermoplastic resin (B),
The present invention provides a method for producing a molded product, comprising 4) a step of mixing the small piece material and an isocyanate compound to form a mixture, and 5) a step of pressure molding the mixture at room temperature.

In the present invention, the step 3 can also be performed after the step 4.
That is, the present invention
1) A step of mixing an emulsion of the thermoplastic resin (A) and a small piece of material,
2) A step of drying the obtained mixture to form a small piece material with the dried thermoplastic resin (A) attached to the surface,
3) A step of mixing the small piece material and the isocyanate compound to form a mixture,
4) A method for producing a molded product, comprising a step of moistening the small piece material obtained in step 3) with an emulsion or an aqueous solution of the thermoplastic resin (B), and 5) a step of pressure molding the mixture at room temperature. It is to provide.

Preferably, the step of wetting with an emulsion or an aqueous solution of the thermoplastic resin (B) is performed after the small piece material and the isocyanate compound are mixed to form a mixture.
Wetting with an emulsion or aqueous solution of the thermoplastic resin (B) is considered to promote the reaction between the thermoplastic resin and the isocyanate compound, thereby improving the bonding force, and as a result, a molded product having excellent bending strength and water resistance can be obtained. it is conceivable that.

As described above, the present invention aims to improve the invention described in Japanese Patent Application No. 2002-344902. When compared with a conventionally known technique, the present invention has an effect based on the invention described in the above patent. In addition to the effects, the effects resulting from the method of the present invention are also exhibited.
That is, in the prior art, it is necessary to heat and compress at the time of molding, but in the present invention, this is not necessary, and the energy cost is greatly reduced. Since it is pressure-molded at room temperature, it has a feature that deformation such as warpage of the molded product is small. In addition, the degree of freedom in the shape of the molded product increases, and it becomes easy to produce particularly thick molded products and curved molded products.

Since the molded product according to the present invention is obtained by pressure molding at room temperature using a thermoplastic resin and an isocyanate compound, the energy cost required for heating is minimized. Since a plastic resin is used, there is no major health risk in the manufacturing process due to formaldehyde, and there are no problems due to residual formaldehyde in the resulting product.
The molded product obtained by the present invention is strong, excellent in physical properties including strength, and excellent in water resistance. Furthermore, in the method of the present invention, a molded product having excellent bending strength can be obtained in a particularly short pressing time.

Since the particle size and shape of the small piece material used in the present invention varies depending on the material and the type of molded product to be produced, required performance, etc., those skilled in the art can appropriately select the material. it can. As the piece-like material, a woody material derived from wood such as a piece of wood, wood fiber, or bark is preferably used. Wood waste such as plywood, waste paper such as newspapers and magazines, paper tubes, cardboard, charcoal, rice chaff, corn, rubber trees, straw, sorghum stem, kenaf, and other materials can also be used. These materials can be used by breaking and crushing to an appropriate size if necessary. A preferred piece of material is a woody material.
When using a wood material, the kind of the tree is not limited, but those derived from conifers such as pine, cedar and cypress, and broad-leaved trees such as lauan, capol, poplar and willow are preferably used. When wood chips are used as the small piece material, those having a size of 0.01 to 100 mm are generally used. A plurality of kinds of small piece materials can be mixed and used depending on the application.

The thermoplastic resins (A) and (B) used in the present invention only need to have thermoplasticity, and may be any of natural resins and synthetic resins. Moreover, as long as it has thermoplasticity, you may have some bridge | crosslinking.
The resin suitably used as the thermoplastic resin (A) is a vinyl acetate resin, an ethylene-vinyl acetate copolymer resin, a copolymer of ethylenically unsaturated monomers including an acrylic ester and / or a methacrylic ester. Examples thereof include acrylic resins, styrene butadiene copolymers, and polyvinyl alcohol.
Examples of the resin suitably used as the thermoplastic resin (B) include vinyl acetate resin, ethylene-vinyl acetate copolymer resin, and polyvinyl alcohol. These thermoplastic resins can be used alone or in combination.

The thermoplastic resin excluding polyvinyl alcohol used in the present invention is preferably produced and provided by emulsion polymerization from the viewpoints of safety, environment, and the like. The method for emulsion polymerization is not particularly limited and may be a normal method. For example, a monomer such as vinyl acetate can be obtained by adding an initiator such as persulfate in water in the presence of various emulsifiers and protective colloids. , Sequential addition, divided addition, etc.), type of emulsifier (anionic emulsifier, nonionic emulsifier, cationic emulsifier, etc.), type of protective colloid (polyvinyl alcohol polymer, cellulose polymer, etc.), type of initiator ( Persulfates, peroxides such as hydrogen peroxide, reducing agents such as sodium bisulfite used for redox reaction with them) and addition methods (batch addition, sequential addition, divided addition, etc.) and other stirring conditions, polymerization Polymerization conditions including temperature and the like are known and can be appropriately determined by those skilled in the art as needed.
In addition, an emulsion obtained by a seed emulsion polymerization method in which vinyl acetate is emulsion-polymerized in the presence of an ethylene-vinyl acetate copolymer emulsion can also be used.

  As the thermoplastic resin emulsion, those having a solid content of 20 to 70% are preferably used. The viscosity of the thermoplastic resin emulsion is not particularly limited and varies depending on the solid content concentration, but is preferably 200000 mPa · s (30 ° C.) or less from the viewpoint of workability and the like.

As the vinyl acetate resin, for example, a resin obtained by emulsion polymerization of a vinyl acetate monomer in the presence of a protective colloid can be suitably used.
The vinyl acetate resin emulsion preferably has a viscosity of 1,000 to 200,000 mPa · s. The pH is preferably 3 to 8.

  As the ethylene-vinyl acetate copolymer resin, for example, those obtained by emulsion copolymerization of ethylene and vinyl acetate monomer in the presence of a protective colloid can be preferably used. The ethylene content in the ethylene-vinyl acetate copolymer resin is preferably 5-40% by weight, more preferably 10-25% by weight. The viscosity is preferably 200-20000 mPa · s. Moreover, it is preferable that pH is 4-7.

The polyvinyl alcohol is preferably an aqueous solution, and is desirably used at a resin concentration of 5 to 30%.
As the polyvinyl alcohol used in the present invention, those having various polymerization degrees and saponification degrees can be used, and generally have a polymerization degree of 200 to 4000 and a saponification degree of 50 to 100 mol%.
Preferably, the degree of polymerization is 1000 to 2000, and the degree of saponification is 95 to 100 mol%. Polyvinyl alcohol modified with a hydrophobic group, carboxyl group, sulfonic acid group, cation group, acetoacetyl group, silanol group or the like derived from an α-olefin monomer can also be used.

  Various grades of vinyl acetate resin, ethylene-vinyl acetate copolymer resin, acrylic resin, styrene-butadiene copolymer resin and polyvinyl alcohol are commercially available from many manufacturers, and can be selected appropriately according to the desired characteristics. Can be used.

  As the isocyanate compound used in the present invention, a compound having two or more isocyanate groups can be used. For example, tolylene diisocyanate (TDI), hydrogenated TDI, trimethylolpropane-TDI adduct, triphenylmethane triisocyanate, diphenylmethane. Diisocyanate (MDI), hydrogenated MDI, hexamethylene diisocyanate (HMDI), xylylene diisocyanate (XDI), metaxylylene diisocyanate, hydrogenated XDI, isophorone diisocyanate, lysine diisocyanate, dimer diisocyanate, water or amine adduct of the above isocyanate compound Various adducts such as, oligomers such as dimers or trimers of the above isocyanate compounds, polyisocyanate in excess of polyol Luo beforehand polymerized was terminated urethane prepolymer having an isocyanate group, terminal isocyanate groups, such as blocked urethane blocked the like. These containing various isomers are used alone or in combination of two or more. Among these, so-called polymeric MDI containing a dimer or higher MDI is preferably used from the viewpoint of economy and the like.

A known catalyst can be added for the purpose of accelerating the curing of the isocyanate compound.
For example, triethylamine, triethylenediamine, N-methylmorpholine, N-methylimidazole, 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole, 1-cyanomethylimidazole, 1,2-dimethylimidazole, 1,4- Dimethylimidazole, 1-methyl-2-ethylimidazole, 1-methyl-4-ethylimidazole, 1-ethyl-2-methylimidazole, 1-ethyl-4-methylimidazole, pyridine, α-picoline, monoethanolamine, diethanolamine , Triethanolamine, N, N, N′-trimethylaminoethylethanolamine, N, N, N ′, N′-tetramethylhydroxypropylenediamine, dibutyltin dilaurate, dioctyltin dilaurate, naphthe Calcium acid, octyl potassium, tin octylate, zinc octylate and the like. The addition amount is preferably 0.1 to 20 parts by weight with respect to 100 parts by weight of the isocyanate compound. If the amount is 0.1 parts by weight or less, there is no effect of promoting curing, and if 20 parts by weight or more is added, the bonding strength decreases.

  In the present specification, the “small piece material with the dried thermoplastic resin (A) attached to the surface thereof may be any material as long as the thermoplastic resin (A) is present on the small piece material surface in a dry state, Drying refers to a state in which water is almost exhausted, specifically, a state in which water is reduced to such an extent that significant foaming does not occur even when an isocyanate compound is added. ) Of the emulsion is substantially evaporated, and a dry film of the translucent or transparent resin of the thermoplastic resin (A) is formed.

  The mixing amount of the thermoplastic resin (A) emulsion to the small piece material varies depending on the type of the material. For example, the solid content of the emulsion is 5 to 100 parts by weight of wood chips (water content 5-15%). 50 parts by weight, preferably 10-40 parts by weight. If the amount of resin is small, the bonding force becomes insufficient, and if the amount of resin is too large, the corresponding increase in bonding force cannot be obtained.

  The mixing amount of the isocyanate compound with respect to the small piece material varies depending on the kind of the material, but for example, 1 to 20 parts by weight, preferably 5 to 15 parts by weight with respect to 100 parts by weight of wood chips (water content 5 to 15%). It is. If the amount of the isocyanate compound is small, the bonding strength becomes insufficient, and if the amount of the isocyanate compound is too large, the corresponding increase in bonding strength cannot be obtained.

  The amount of the thermoplastic resin (B) emulsion or aqueous solution used is, for example, 15% by weight or less with respect to 100% by weight of wood chips (water content 5-15%). Addition of 15% by weight or more is not preferable because the molded product is deformed by moisture.

The small piece material can be used after being washed with water and dried if necessary. Mixing of the thermoplastic resin (A) and the small piece material can be performed by any known method, for example, spray coating or impregnation. A mixing method, a mixing apparatus, a mixing time, and the like can be appropriately selected according to the type and size of the small piece material and the type and mixing ratio of the thermoplastic resin (A). Thorough mixing is desirable so that the thermoplastic resin (A) is present on the entire surface of the piece-like material.
The obtained mixture can also be dried by a known method. For example, any method such as air drying at room temperature, hot air drying, and heat drying in an oven can be used.

  Mixing of the small piece material with the dried thermoplastic resin (A) attached to the surface thereof and the emulsion or aqueous solution of the isocyanate compound and the thermoplastic resin (B) can be performed by any known method, for example, spraying It can be performed by a method such as coating or impregnation. A mixing method, a mixing apparatus, a mixing time, and the like can be appropriately selected according to the type and size of the small piece material on which the dried thermoplastic resin (A) is adhered. It is desirable to mix thoroughly so that the emulsion or aqueous solution of an isocyanate compound and a thermoplastic resin (B) exists in the whole surface of the small piece-like material which the thermoplastic resin (A) of the dry state adhered to the surface.

In the method for producing a molded product of the present invention, the pressure molding time varies depending on the type of material, but typically a short time of about 1 to 30 minutes is sufficient. Further, the applied pressure varies required performance required of the molded product, typically it is sufficient from 1 kgf / cm ² at a pressure of 50 kgf / cm ^2.

  In the method of the present invention, the molding is performed at room temperature. In this specification, “normal temperature” means a temperature from 0 ° C. to 100 ° C. The molding temperature is preferably 10 ° C to 90 ° C, more preferably 20 ° C to 80 ° C, and most preferably 30 ° C to 70 ° C. If pressure molding is performed at an extremely low temperature such as less than 0 ° C., the bonding force is weak and cannot be handled as a molded product.

  In order to prevent moisture absorption deformation of the molded product, a water repellent such as paraffin wax may be added. Moreover, a filler, a solvent, a pigment, a dye, a preservative, an insecticide, an antifoaming agent, etc. can be added as needed.

The molded product obtained by the present invention can be used for various purposes, but typically, it is a building material such as a roof base material, a flooring material, a wall material, a woodwork material such as furniture, and a plantation. In order to prevent the growth of weeds, etc., it can be used as a vegetation material such as a board to be installed and a water retention board for plants, and as a cushioning material used as a packing material (an alternative to foamed polystyrene, etc.).
In particular, when used as a building material, it is characterized by excellent heat insulation and soundproofing.
In addition, the method of the present invention can be molded with little foaming resulting from the reaction between moisture and an isocyanate compound. The obtained molded product is strong, excellent in physical properties such as strength, and excellent in water resistance.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, a following example does not restrict | limit the scope of the present invention at all.
Example 1
Take 5000 g of wood chips (water content of cedar through a 15 mm mesh, approx. 12%) in a container. Ethylene vinyl acetate copolymer resin emulsion (trade name Panflex OM6000, viscosity 2500 mPa · s, solid content 50%, polyvinyl alcohol, Kuraray Co., Ltd. 2000 g) was added and mixed with sufficient stirring, then separated and dried at 60 ° C. for 3 hours to obtain a wood chip mixture. The mixture was allowed to stand at room temperature (30 to 35 ° C.) for 1 day, and stirred at the same temperature. Further, an isocyanate compound (trade name Woodcure 300 manufactured by Nippon Polyurethane Industry Co., Ltd., main component MDI, NCO content 28.5- 30.5%) and 500 g of 10% by weight aqueous polyvinyl alcohol solution (trade name: Kuraray Poval 117, saponification degree: 98 mol%, polymerization degree: 1700, manufactured by Kuraray Co., Ltd.) It was put into (width 300 mm × length 600 mm) and pressure-molded (30 kgf / cm ² ). After leaving at the same temperature for 10 minutes, the pressure was released and the product was taken out from the mold to obtain a molded product having a height of 25 mm. When this molded product was used as a shelf for a bookcase, it was not practically twisted or distorted and could be put to practical use.

Example 2
Take 5000 g of wood chips (water content of cedar through 15 mm mesh about 12%) in a container, and 2000 g of vinyl acetate resin emulsion (trade name Bond CX55, viscosity 25000 mPa · s, solid content 55%, polyvinyl alcohol contained, manufactured by Konishi Co., Ltd.) The mixture was added and sufficiently stirred and mixed, then separated and dried at 60 ° C. for 3 hours to obtain a wood chip mixture. The mixture was allowed to stand at room temperature (60 to 70 ° C.) for 1 day, and stirred at the same temperature. Further, an isocyanate compound (trade name Woodcure 300 made by Nippon Polyurethane Industry Co., Ltd., main component MDI, NCO content 28.5- 30.5%) and then 10 g of polyvinyl alcohol aqueous solution (trade name: Kuraray Poval 117, saponification degree: 98 mol%, polymerization degree: 1700, manufactured by Kuraray Co., Ltd.) respectively, and after mixing well, mold and poured into a frame (width 300 mm × length 600 mm) was pressure-molded (30kgf / cm ^2). After leaving at the same temperature for 10 minutes, the pressure was released and the product was taken out from the mold to obtain a molded product having a height of 25 mm. When this molded product was used as a shelf for a bookcase, it was not practically twisted or distorted and could be put to practical use.

Example 3
Take 5,000 g of wood chips (water content of cedar through a 15 mm mesh of about 12%) in a container, and use acrylic ester copolymer resin emulsion (trade name Kuraray Co., Ltd., viscosity 10000 mPa · s, solid content 50% polyvinyl alcohol, methacrylic acid 2000 g of methyl / butyl acrylate copolymer resin) was added and mixed with sufficient stirring, and then separated and dried at 60 ° C. for 3 hours to obtain a wood chip mixture. The mixture was allowed to stand at room temperature (35 to 40 ° C.) for 1 day, and stirred at the same temperature. Further, an isocyanate compound (trade name Woodcure 300 manufactured by Nippon Polyurethane Industry Co., Ltd., main component MDI, NCO content 28.5- 30.5%) and then 10 g of polyvinyl alcohol aqueous solution (trade name Kuraray Poval 117, saponification degree 98 mol%, polymerization degree 1700, manufactured by Kuraray Co., Ltd.) by spray coating and mixing well, then mold It put into the frame (width 300 * length 600mm) and pressure-molded (30kgf / cm < ² >). After leaving at the same temperature for 10 minutes, the pressure was released and the product was taken out from the mold to obtain a molded product having a height of 25 mm. When this molded product was used as a shelf for a bookcase, it was not practically twisted or distorted and could be put to practical use.

Example 4
Put 5000 g of wood chips (water content of cedar through 15 mm mesh about 12%) in a container and 2000 g of styrene butadiene copolymer latex (trade name Nipol LX430, viscosity 130 mPa · s, solid content 49%, manufactured by Zeon Corporation) The mixture was added and sufficiently stirred and mixed, then separated and dried at 60 ° C. for 3 hours to obtain a wood chip mixture. The mixture was allowed to stand at room temperature (40 to 50 ° C.) for 1 day and stirred at the same temperature, and further an isocyanate compound (trade name Woodcure 300 manufactured by Nippon Polyurethane Industry Co., Ltd., main component MDI, NCO content 28.5- 30.5%) and then 10 g of polyvinyl alcohol aqueous solution (trade name Kuraray Poval 117, saponification degree 98 mol%, polymerization degree 1700, manufactured by Kuraray Co., Ltd.) by spray coating and mixing well, then mold and poured into a frame (width 300 mm × length 600 mm) was pressure-molded (30kgf / cm ^2). After leaving at the same temperature for 10 minutes, the pressure was released and the product was taken out from the mold to obtain a molded product having a height of 25 mm. When this molded product was used as a shelf for a bookcase, it was not practically twisted or distorted and could be put to practical use.

Comparative Example 1-4
In Examples 1 to 4, except that the step of drying at 60 ° C. for 3 hours and leaving at room temperature for 1 day was omitted, the process was carried out in the same manner as in the example. It was difficult to continue.

Example 5-9
Take 20 g of wood chips (cedar passing through 4 mm mesh, mixed cypress wood, water content of about 12%) in a container, ethylene vinyl acetate copolymer resin emulsion (trade name Panflex OM6000, viscosity 2500 mPa · s, solid content 50%, polyvinyl alcohol Containing, manufactured by Kuraray Co., Ltd.) with stirring, the amounts shown in Table 1 were added and mixed well, then separated and left to dry at room temperature (35 to 40 ° C.) for 2 days to obtain a wood chip mixture. It was. While stirring at the same temperature, 2 g of an isocyanate compound (trade name Wood Cure 300, manufactured by Nippon Polyurethane Industry Co., Ltd., main component MDI, NCO content 28.5-30.5%), followed by 10% by weight polyvinyl alcohol aqueous solution (product) 2g of Kuraray Poval 117, degree of saponification 98mol%, polymerization degree 1700 made by Kuraray Co., Ltd.) are spray-coated and mixed thoroughly before being put into a formwork (width 20mm x length 100mm x height 100mm) Pressure molding (30 kgf / cm ² ) was performed. The mixture was allowed to stand at the same temperature for 10 minutes and then decompressed, removed from the mold, and left at room temperature (30 ° C.) for 7 days to obtain a molded product (width 20 mm × length 100 mm × height about 20 mm). The obtained molded product was subjected to a three-point bending strength test according to JIS K7171. The results are shown in Table 1.

Table 1
Example Ethylene vinyl acetate copolymer resin Molded product bending strength
Emulsion (g) (kgf / cm ² )
5 4 250
6 6 260
7 8 263
8 12 280
9 16 281

Comparative Example 5-9 Table 2 shows the results obtained in the same manner as in Examples 5 to 9 except that the aqueous polyvinyl alcohol solution was not added.

Table 2
Comparative Example Ethylene Vinyl Acetate Copolymer Resin Bending Strength
Emulsion (g) (kgf / cm ² )
5 4 55
6 6 83
7 8 130
8 12 161
9 16 162

From Examples 5 to 9, a molded product having excellent bending strength was obtained by crosslinking the ethylene vinyl acetate copolymer resin, the isocyanate compound, and polyvinyl alcohol.
In Comparative Examples 5 to 9 to which no aqueous polyvinyl alcohol solution is added, a molded product is obtained, but the bending strength is weak.

Examples 10-12
Take 20 g of wood chips (4 mm mesh cedar, cypress mixed, water content approx. 12%) in a container, ethylene vinyl acetate copolymer resin emulsion (trade name Panflex OM6000, viscosity 2500 mPa · s, solid content 50%, containing polyvinyl alcohol (Manufactured by Kuraray Co., Ltd.) was added and sufficiently stirred and mixed, then separated and left to dry at room temperature (35 to 40 ° C.) for 2 days to obtain a wood chip mixture. At the same temperature, the isocyanate compounds (trade name Wood Cure 300 manufactured by Nippon Polyurethane Industry Co., Ltd., main component MDI, NCO content 28.5-30.5%) were continuously added to the wood chips while stirring the amounts shown in Table 3. 2 g of polyvinyl alcohol aqueous solution (trade name Kuraray Poval 117, degree of saponification 98 mol%, degree of polymerization 1700, manufactured by Kuraray Co., Ltd.) was spray-coated and mixed thoroughly before forming a mold (width 20 mm × length 100 mm). × Height 100 mm) and press-molded (30 kgf / cm ² ). The mixture was allowed to stand at the same temperature for 10 minutes and then decompressed, removed from the mold, and left at room temperature (30 ° C.) for 7 days to obtain a molded product (width 20 mm × length 100 mm × height about 20 mm). The obtained molded product was subjected to a three-point bending strength test according to JIS K7171. The results are shown in Table 3.

Table 3
Example Isocyanate Compound (g) Bending Strength of Molded Product (kgf / cm ² )
10 1 170
7 2 263
11 3 302
12 4 303
Comparative Example 10 0 55

  In Examples 7 and 10 to 12, the bending strength of the molded product is improved by adding an isocyanate compound.

Example 13: Water resistance test The molded product obtained in Example 11 was immersed in water at 30 ° C for 7 days and taken out, and almost no expansion and contraction was observed. It was.

Examples 14-15
Take 20 g of wood chips (4 mm mesh cedar, cypress mixed, water content approx. 12%) in a container, ethylene vinyl acetate copolymer resin emulsion (trade name Panflex OM6000, viscosity 2500 mPa · s, solid content 50%, containing polyvinyl alcohol (Manufactured by Kuraray Co., Ltd.) was added and sufficiently stirred and mixed, then separated and left to dry at room temperature (35 to 40 ° C.) for 2 days to obtain a wood chip mixture. At the same temperature while stirring, 3 g of an isocyanate compound (trade name Wood Cure 300, manufactured by Nippon Polyurethane Industry Co., Ltd., main component MDI, NCO content 28.5-30.5%) was further added, followed by 10% by weight polyvinyl alcohol aqueous solution ( The product name Kuraray Poval 117, saponification degree 98 mol%, polymerization degree 1700 made by Kuraray Co., Ltd. was spray-coated in the amounts shown in Table 4 and mixed thoroughly before forming (width 20 mm x length 100 mm x height) 100 mm) and press-molded (30 kgf / cm ² ). The mixture was allowed to stand at the same temperature for 10 minutes and then decompressed, removed from the mold, and left at room temperature (30 ° C.) for 7 days to obtain a molded product (width 20 mm × length 100 mm × height about 20 mm). The obtained molded product was subjected to a three-point bending strength test according to JIS K7171. The results are shown in Table 4.

Table 4
Example 10% by weight polyvinyl molded product bending strength
Alcohol aqueous solution (g) (kgf / cm ² )
14 1 271
11 2 302
15 3 293

Comparative example 11 In Example 14, it carried out similarly to Example 14 except not adding 10 weight% polyvinyl alcohol aqueous solution, As a result, the molding bending strength was 135 kgf / cm < ² >.

Example 16
Take 5,000 g of wood chips (water content of cedar through 15 mm mesh about 15%) in a container, and make ethylene vinyl acetate copolymer resin emulsion (trade name Panflex OM6000, viscosity 2500 mPa · s, solid content 50%, polyvinyl alcohol, Kuraray Co., Ltd. 2000 g) was added and mixed with sufficient stirring, then separated and dried at 60 ° C. for 3 hours to obtain a wood chip mixture. This mixture was allowed to stand at room temperature (35 to 40 ° C.) for 1 day, and further at the same temperature, an isocyanate compound (trade name Woodcure 300 manufactured by Nippon Polyurethane Industry Co., Ltd., main component MDI, NCO content 28.5-30.5% ) 250 g, spray-coating with stirring and mixing well, then ethylene vinyl acetate copolymer resin emulsion (trade name Panflex OM6000, viscosity 2500 mPa · s, solid content 50%, containing polyvinyl alcohol, Inc. After spraying 750 g (made by Kuraray), the mixture was intermittently pressed into a mold having the shape shown in FIG. 1 and then press-molded (30 kgf / cm ² ). After leaving at the same temperature for 10 minutes, the pressure was released and the product was taken out from the mold to obtain a molded product. The obtained molding had sufficient strength to be handled.

Example 17
1000g of wood planer scraps (mixed with cedar and cypress wood, sieved with 10mm mesh sieve, left on sieve, water content 15%) in a container, ethylene vinyl acetate copolymer resin emulsion (trade name Panflex OM6000, viscosity 2500 mPa · s) Then, 300 g of a solid content of 50%, containing polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) was added and sufficiently stirred and mixed, then separated and dried at 60 ° C. for 3 hours to obtain a wood planer scrap mixture. This mixture is allowed to stand at room temperature (25 to 30 ° C.) for 1 day, and further 100 g of an isocyanate compound (trade name Wood Cure 300, manufactured by Nippon Polyurethane Industry Co., Ltd., main component MDI, NCO content 28.5-30.5%) Further, 100 g of a 10% by weight aqueous polyvinyl alcohol solution (trade name Kuraray Poval 117, saponification degree 98 mol%, polymerization degree 1700, manufactured by Kuraray Co., Ltd.) was spray-coated and sufficiently mixed. 144 g of the obtained mixture was put into a mold (width 120 mm × length 170 mm × height 100 mm) at the same temperature (25 to 30 ° C.) and foamed, and then the pressing time shown in Table 5 at a pressure plate temperature of 50 ° C. And clamped (30 kgf / cm ² ). The obtained molding was left at room temperature (25 to 32 ° C.) for 7 days, and a three-point bending strength test was conducted according to JIS K7171. The results are shown in Table 5.

Table 5
Clamping time (min) Bending strength of molded product (kgf / cm ² )
2 88
6 200
10 236
20 278
60 324

Comparative Example 12
In Example 17, it carried out like Example 12 except having replaced 10 weight% polyvinyl alcohol aqueous solution with water. The results are shown in Table 6.

Table 6
Clamping time (min) Bending strength of molded product (kgf / cm ² )
2 48
6 162
10 211
20 251
60 289

  As is apparent from Tables 5 and 6, the polyvinyl alcohol aqueous solution is clearly superior in bending strength as compared with water, and is evident particularly in a short pressing time.

In the molded product of the present invention, by providing a crosslinked structure with an isocyanate compound, a molded product having excellent bending strength and water resistance can be obtained by pressure molding at room temperature for a short time. In particular, a molded product having excellent performance can be obtained by crosslinking the hydroxyl group of polyvinyl alcohol and the isocyanate group of the isocyanate compound to form a urethane bond.
Further, as is apparent from the results of the examples, the molded product of the present invention has sufficient strength, and the molded product can be efficiently produced at a low energy cost by the molding method of the present invention.

FIG. 1 is a diagram of a mold used in Example 16.

Claims (6)

1) A step of mixing a thermoplastic resin (A) emulsion and a small piece of material to obtain a mixture ;
2) The mixture obtained in the above step 1) is dried to such an extent that no significant foaming occurs even when an isocyanate compound is added to reduce moisture, and small pieces with the thermoplastic resin (A) adhering to the surface. Forming a material;
3) A step of mixing the flaky material obtained in the above step 2) and an isocyanate compound to form a mixture,
4) a step of wetting the mixture obtained in the above step 3) with an emulsion or an aqueous solution of the thermoplastic resin (B), and 5) a mixture obtained in the above step 4) in a temperature range of 20-100 ° C. A process for producing a molded product comprising a step of pressure molding ,
The thermoplastic resin (A) is at least one resin selected from the group consisting of vinyl acetate resin, ethylene-vinyl acetate copolymer resin, acrylic resin, and styrene-butadiene copolymer, and the thermoplastic resin (B) is The manufacturing method which is at least 1 resin selected from the group which consists of vinyl acetate resin, ethylene-vinyl acetate copolymer resin, and polyvinyl alcohol. The manufacturing method according to claim 1, wherein the piece-like material is a wood material. The manufacturing method of Claim 1 or 2 that a thermoplastic resin (A) exists in the quantity of 5 to 50 weight% with respect to a small piece-like material. The production method according to claim 1 or 2, wherein the thermoplastic resin (B) is present in an amount of less than 15% by weight based on the small piece material. The production method according to any one of claims 1 to 4, wherein the isocyanate compound is present in an amount of 1 to 20% by weight relative to the small piece material. The manufacturing method of any one of Claim 1 to 5 in which an isocyanate compound contains the diphenylmethane diisocyanate (MDI) type | system | group of a dimer or more.

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