JPH0732323A - Manufacture of woody panel - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a woody panel, of low density, light and still of sufficient strength. CONSTITUTION:A first layer 14 composed of woody fiber and coated with a binder is formed, over which a plate 10 composed at least of one thermoplastic foaming resin is laminated. A second layer is formed by disposing a mixture 15 composed of woody fiber and thin wood pieces and coated with the binder is disposed in a manner of encircling the side face periphery of the plate 10. A third layer 12 composed of woody fiber and coated with the binder is laminated on the second layer, and then the laminate is heat pressurized at the temperature of melting point of thermoplastic foaming resin or over and mold integrated. As a woody panel manufactured by the above-said process is provided with a hollow section inside, the density of the whole of woody panel can be lowered and its strength and rigidity can be retained, and its surface can be formed smooth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wood panel, and more specifically, it has a hollow portion inside and is lightweight.
Moreover, the present invention relates to a method for manufacturing a wood panel that retains high strength.

[0002]

2. Description of the Related Art A wood panel using wood fibers, wood flakes, etc. is also effective in protecting wood resources because wood fibers, wood flakes, etc., which have been conventionally discarded, can be effectively used.
By changing the molding die, it is possible to obtain the material of the required size and shape with relative ease.By modifying the constituent elements or adding additives, the insect repellent, It is possible to improve antiseptic property, flame retardancy and the like, and it is possible to impart characteristics not found in natural wood. These wood panels are generally formed by adhering components such as wood flakes and wood fibers with a binder such as phenol resin, urea resin, melamine resin, and integrally molding them.

However, these wood panels tend to have a higher density than natural wood having voids such as pores therein, and when the amount of the binder is reduced to lower the density, the wood panel is obtained. There was a problem that the strength of the Further, there is a problem in that the surface smoothness of the wood panel is lost when the density of the wood panel is reduced while maintaining the strength by increasing the size of the constituent elements of the wood panel. Therefore, it is difficult to use such a wood panel as a plate material such as a door material that is required to be large and lightweight.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a manufacturing method for obtaining a wood panel which has a low density, is lightweight, and has sufficient strength.

[0005]

This problem is solved by forming a first layer made of wood fibers coated with a binder, laminating at least one plate made of thermoplastic foamed resin on the first layer, and A second layer is formed by arranging a mixture of binder-coated wood fibers and wood flakes so as to surround the periphery of the side surface, and further laminating a third layer of binder-coated wood fibers thereon. After forming the laminated body, the laminated body can be solved by a method of manufacturing a wood panel in which the laminated body is hot pressed at a temperature equal to or higher than the melting point of the thermoplastic foamed resin to be integrally molded.

The wood panel manufactured by the manufacturing method of the present invention has one or more hollow portions inside.
FIG. 1 shows an example of a wood panel manufactured by the manufacturing method of the present invention. This wood panel 1 has two hollow portions 3 on the upper surface of one surface layer material 4 made of a medium-density wood fiber molded board, and a core material 5 made of wood fiber / wood flakes molded board is laminated on the surface layer material 4. On the upper surface of the core material 5, the other surface layer material 2 made of a medium-density wood fiber molded plate is laminated and integrally molded.

In such a wood panel, as shown in FIG. 2, first, wood fibers coated with a binder are uniformly dispersed to form a first layer 14. On the first layer 14, a plate material 10 made of thermoplastic foam resin such as Styrofoam.
Are stacked. Next, the periphery of the side surface of the plate material 10 is filled with a mixture 15 of wood flakes and wood fibers coated with a binder so that the thickness thereof is the same as the thickness of the plate material 10 of the thermoplastic foamed resin. The second layer. Further, a wood fiber coated with a binder is laminated on the second layer to form a third layer 12.

The three-layer laminate thus obtained is compressed from above and below in the drawing and heated to be integrally molded. In this hot-pressing process, when the temperature does not reach the melting point of the thermoplastic foamed resin, the thermoplastic foamed resin plate material is compression-molded with the plate material therein, and the binder is solidified and integrated to form the basic wood panel 1. A shape is formed. After that, when the temperature is further raised and exceeds the melting point of the thermoplastic foamed resin, the thermoplastic foamed resin melts and shrinks, and the hollow portion 3 is formed to obtain the wood panel having the shape shown in FIG.

According to the method for manufacturing a wood panel of the present invention, the first layer 14 is thermocompressed to form one surface layer material 4, and similarly, the core material 5 is formed from the second layer. The other surface layer material 2 is generally formed from the layer 12 of No. 3, but they are not independent of each other, but are integrally molded in a state in which the surface layer material / core material / surface layer material are laminated.

The thermoplastic foam resin plate material 10 used in the method for manufacturing a wood panel of the present invention is a plate material made of a thermoplastic resin, and is preferably foamed and of low density. As the thermoplastic resin, Styrofoam is a typical example, but it is not particularly limited as long as it melts at the thermocompression molding temperature or lower of the wood panel, for example,
A self-foamed resin such as a foamable polyurethane resin or a resin foamed by a foaming agent may be used.

Examples of the resin foamed by the foaming agent include thermoplastic polyurethane resin, polyethylene resin, polyvinyl chloride resin or a mixture thereof, and as the foaming agent, a volatile foaming agent such as CCl ₃ F or CC.
l ₂ F ₂ , CCl ₂ F-CClF ₂ or the like, or a thermally decomposable foaming agent such as azodicarbonamide, azohexahydrobenzonitrile, 2,2′-azoisobutyronitrile, benzenesulfohydrazide, or N, N'-dinitroso-N, N'-dimethyl terephthalamide etc. can be mentioned.

As such a thermoplastic foam resin, a thermoplastic resin molded into a plate having a desired size by a conventional method is used. The shape and size of the thermoplastic foam resin plate material 10 are not particularly limited, and can be appropriately changed depending on the shape, strength, thickness, etc. of the target wood panel. Especially when high strength is required, it is preferable to reduce the volume of the hollow portion by lowering the proportion of the thermoplastic foaming resin in the second layer, and particularly when weight reduction is required, It is preferable to increase the ratio to increase the volume of the hollow portion.

The first layer and the third layer in the method for manufacturing a wood panel of the present invention are preferably made of the same material, and it is preferably wood fiber coated with a binder. Further, the surface layer material which is roughly formed by thermocompressing the first layer and the third layer is a medium-density wood fiber molding plate in which wood fibers are bonded and integrated by a binder. Is preferred. That is, the density of this surface material is
It is preferable to adjust so as to be 0.40 to 0.65 g / cm ³ . If the density is higher than 0.65 g / cm ³ , the weight of the resulting wood panel will increase to 0.40 g / cm ^3.
If it is smaller than cm ³ , the surface smoothness becomes insufficient.

The wood fibers forming the first layer and the third layer are obtained by defibrating wood chips by a conventional method, and the fiber length thereof is about 1 to 30 mm, preferably 3 mm. It is preferable that the fibers having the above lengths account for 50% or more of the whole and the fiber width is about 0.1 to 2 mm. This wood fiber is preferably acetylated in advance. In that case, the wood fiber is dried to a water content of 3% or less, preferably 1% or less, and then vaporized with vapor such as acetic acid, acetic anhydride or chloroacetic acid. It is preferable to contact and acetylate in the gas phase (degree of acetylation: 12 to 20%). Further, as the binder for bonding and integrating these wood fibers, it is preferable to use a non-foaming binder such as urea resin, melamine resin or phenol resin as a main component from the viewpoint of releasability from the mold.

In the first layer and the third layer, the ratio of the binder to the wood fiber is 1
It is preferably 5 parts by weight or more with respect to 00 parts by weight.
When the addition amount of the binder is 5 parts by weight or less with respect to 100 parts by weight of wood fiber, the strength of the obtained surface layer material becomes insufficient. Moreover, the thickness of the surface layer material is preferably 3 to 4 mm, and when the thickness is 3 mm or less, the surface smoothness of the obtained wood panel becomes insufficient, and when it is 4 mm or more, the weight of the wood panel is Will increase.

In the second layer of the method for manufacturing a wood panel of the present invention, the material disposed around the thermoplastic foamed resin plate material is a mixture of wood fibers and wood flakes coated with a binder. It is preferable that the core material formed by thermocompressing it is a wood fiber / wood flakes molded plate. The wood fibers used in the second layer are preferably wood fibers similar to those used in the first and third layers, and the wood flakes have a length of 20 to 100 mm.
It is preferable that the width is 3 to 5 mm and the thickness is 0.2 to 0.8 mm. The mixing ratio of wood fibers and wood flakes can be appropriately set according to the purpose, but in order to improve the strength in particular, the proportion of wood flakes is increased, and in order to improve the smoothness of the surface. It is preferable to increase the proportion of wood fibers.

As the binder for adhering and integrating a mixture of these wood fibers and wood flakes, any of the above-mentioned non-foaming binder, foaming binder such as foaming urethane resin, or a mixture thereof can be used. In order to reduce the density and reduce the weight of the core material to be used, those containing a foamable resin are preferable. The mixing ratio of the non-foaming resin and the foaming resin can be appropriately adjusted depending on the desired density.

In the second layer, the ratio of the binder to the mixture of wood fibers and wood flakes is preferably 10 to 30 parts by weight based on 100 parts by weight of the mixture of wood fibers and wood flakes. The density of the obtained core material is
It is preferably about 0.60 g / cm ³ . When the density is less than 0.60 g / cm ³ , the strength of the wood panel becomes insufficient. The bending strength of this core material is 40 to 50.
The pressure is preferably MPa, and the screw retention force according to JIS-A5908 is preferably 40 to 70 kg.

In the method for producing a wood panel of the present invention, the first method described above is used.
It is preferable that the layers from No. 3 to No. 3 are subjected to dry forming in a thermocompression molding machine, and hot pressing is applied to the dry-formed laminated product. The hot pressure condition varies depending on the melting point of the thermoplastic foam resin used, but the pressure is 1 to 2MP.
a, the temperature is 150 to 200 ° C., and the time is preferably the target thickness of the wood panel (mm) × 5 to 120 seconds. Further, this thermocompression molding is carried out by raising the temperature to a temperature below the melting point of the thermoplastic foamed resin while applying pressure, and after molding at that temperature for a certain time, to a temperature above the melting point of the thermoplastic foamed resin. The temperature may be raised to form the hollow portion, or the molding may be performed while continuously raising the temperature from a low temperature to the melting point of the thermoplastic foamed resin or higher.

As described above, in the wood panel manufactured by the method of the present invention, the core material in which the hollow portion is formed is laminated between the two surface layer materials, so that the density of the whole wood panel is descend. Further, since the core material is made of wood fiber / wood flakes molded plate, strength and rigidity are maintained, and since the surface layer material is made of wood fiber molded plate, the surface of the wood panel becomes smooth. This wood panel can be manufactured by one-time thermoforming.

Next, the method for producing the wood panel of the present invention will be specifically described based on examples. (Example 1) As a material for the first layer and the third layer, a wood fiber (F-4-17, manufactured by Canadian Forest Products Co., Ltd.) containing 50% or more of fibers having a fiber length of 3 mm or more was used.
Prepare 00 parts by weight and 20 parts by weight of non-foaming phenolic resin as a binder, put 100 parts by weight of the above wood fiber in a rotating drum rotating at a low speed, and spray by spraying when falling naturally in the drum. By doing
A binder was applied to the wood fiber.

The material of the second layer is a plate material of thermoplastic foamed resin having a thickness of 75 mm, a width of 100 mm and a length of 2060.
Prepare 2 mm mm styrofoam (70 times foamed product, Dainippon Ink & Co., Ryupearl 70B) boards, and use 50 weight of wood fiber (F-4-17, Canadian Forest Products) as the core material. Part prepared. Also, the length is 20 to 100 mm, the width is 3 to 50 mm, and the thickness is 0.2.
Wood flakes having a thickness of 0.8 mm were produced with a shaving machine (manufactured by Iwakura Gumi Co., Ltd.). Furthermore, 20 parts by weight of a 2: 1 mixture of a non-foaming unconcentrated urea resin and a foaming urethane resin (crude MDI manufactured by Sumitomo Bayer Urethane Co., Ltd.) was prepared as a binder, and the mixture was placed in a rotating drum rotating at a low speed. The binder was applied to the wood fibers and the wood flakes by putting the wood fibers and the wood flakes and spraying them when they spontaneously dropped in the drum.

First, half of the materials of the first layer and the third layer were uniformly dispersed on a hot pressing plate having a width of 400 mm and a length of 2300 mm. Next, two sheets of thermoplastic foamed resin plates were laminated in parallel at intervals of 100 mm, and the periphery of the side face was filled with the material of the core material. Further, the other half of the materials of the first layer and the third layer were evenly spread over the layer to form a laminate as shown in FIG. The laminate was thermoformed at a temperature of 160 ° C. and a pressure of 2 MPa for 20 minutes to obtain a wood panel having a thickness of 21 mm. The obtained wood panel had no warp and the surface was smooth.

The bending strength of the wood panel thus produced was measured according to JIS-A5908. As a result, the bending strength was 38 to 45 MPa. Further, the screw retaining force of this wood board was 50 to 80 kg on the surface and 40 to 70 kg on the wood mouth surface. Furthermore, the density of this wood panel is 0.41 g / cm ³ , and the total weight is 1
It was 2.6 kg.

(Comparative Example 1) The density of an outer-sized wood fiber molded plate similar to the wood panel produced in Example 1 was measured and found to be 0.65 to 0.70 g / cm ³ .
The total weight was 22.0 kg. Further, the screw holding force of the wood fiber molded plate was 50 to 60 kg on the surface and 35 to 40 kg on the mouth end surface. From these results, it is understood that the wood panel manufactured by the manufacturing method of the present invention has a low density, and has a screw retention force equal to or higher than that of the conventional wood fiber molded board and a sufficient bending strength.

According to the method for manufacturing a wood panel of the present invention, a surface layer material, a core material and a plate material of thermoplastic foaming resin are laminated, and the laminate is formed by thermocompression molding. Since the plastic foam resin is melted to form the hollow part, the process of adhering each member is unnecessary, and since it can be manufactured in a single thermocompression molding process, in terms of production efficiency and cost. It is very effective. Further, the wood panel manufactured by the manufacturing method of the present invention has a hollow portion inside, so that the density of the whole wood panel can be reduced,
It is also lightweight as a large plate material such as a door material. In addition, since the core material is a wood fiber / wood flakes molded plate, strength and rigidity are maintained, and since the surface layer material is a medium-density wood fiber molded plate, even if the core material surface has irregularities, the surface of the wood panel Can be smooth.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an example of a wood panel manufactured by a method for manufacturing a wood panel of the present invention.

FIG. 2 is a cross-sectional view for explaining the method for manufacturing the wood panel of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wood panel, 2 ... Surface layer material, 3 ... Hollow part, 4 ... Surface layer material, 5 ... Core material, 10 ... Thermoplastic foam resin board material, 12 ... 1st layer, 14 ... 3rd layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazushi Endo 10-1 Nakazawa-machi, Hamamatsu City, Shizuoka Prefecture Yamaha Stock Company

Claims (3)

[Claims] 1. A first layer made of wood fibers coated with a binder is formed, and at least one plate material made of thermoplastic foamed resin is laminated on the first layer, and a binder is formed so as to surround the side surface of the plate material. A second layer is formed by arranging a mixture of wood fibers coated with and wood flakes, and a third layer of wood fibers coated with a binder is further laminated thereon to form a laminate. A method for producing a wood panel, wherein the laminate is hot pressed at a temperature equal to or higher than the melting point of the thermoplastic foamed resin to be integrally molded. 2. The method for manufacturing a wood panel according to claim 1, wherein the thermoplastic foam resin is styrofoam. 3. A wood panel manufactured by the method according to claim 1.