JP2003039411A - Kenaf composite board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a kenaf composite board having excellent strength and surface smoothness even when the board is formed in a light weight. SOLUTION: The kenaf composite board comprises kenaf fiber layers 2 arranged and formed on surfaces of both sides of a timber veneer 1. The layer 2 is formed of multiple kenaf long fibers 3 each having a length of 20 mm or more and thermosetting resin entangled with each other. The layer 2 is connected to the veneer 1. The layer 2 for constituting a front layer is formed by entangling the fibers 3 each having a fiber length of 20 mm or more and fixed by the thermosetting resin. Even when the layer 2 is formed in the light weight, the layer 2 has the excellent strength and surface smoothness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a kenaf composite board formed by using kenaf and a method for manufacturing the same.

[0002]

2. Description of the Related Art Plywood, particle board and MDF (medium quality fiberboard) are widely used for building materials such as flooring materials, wall materials and ceiling materials, door members, building materials such as skirting boards and rims, and furniture materials. Used in the field. These wood-based boards are veneers obtained by mainly processing softwood or hardwood, or small pieces of wood (particles) and wood fibers bonded with a thermosetting resin or the like to form a board. . For this reason,
Compared to a lumber obtained by lumbering lumber, it has stable quality, has little anisotropy, and has excellent workability.

On the other hand, due to recent global environmental problems, regulations on deforestation have begun to be strengthened for the purpose of protecting forests. In place of the above-mentioned wood board made of wood resources such as conifers and hardwoods, There is an increasing demand for boards that use non-wood resources.

As a board using such a non-wood resource, the present applicant has already obtained it from kenaf (annual herbaceous of the mallow family), oil palm, and bast part of coconut in JP-A-11-333986 and the like. The present invention provides a fiber board in which the long fibers obtained are used as a raw material and the long fibers are oriented in one direction or in an orthogonal direction and bonded with a thermosetting resin. This fiber board has high strength and excellent surface smoothness as compared with conventional wood board.

[0005]

However, JP-A-11-
The fiberboard made of long fibers such as kenaf provided in Japanese Patent No. 333986 has a problem that it is very difficult to maintain strength and surface smoothness while forming a light weight having a specific gravity of 0.6 or less. It was

That is, when producing a fiberboard made of long fibers such as kenaf, it is carried out by hot pressing a long fiber mat in which a thermosetting resin is dispersed, but the specific gravity is 0.6 or less. In order to manufacture the fiberboard of, it is necessary to reduce the compression ratio for compressing the mat of long fibers during thermocompression molding, and as a result, the voids become large inside the fiberboard and The adhesive strength was weakened, the strength was lowered, and the surface smoothness was impaired.

On the other hand, a composite board as shown in FIG. 12 in which a fiber layer 15 obtained by hardening wood fibers with a thermosetting resin is adhered to both surfaces of a wood veneer 1 as seen in Japanese Patent Laid-Open No. 3-254902. Although provided, wood fibers, which are generally short fibers, do not have the fibers entangled with each other. Therefore, in order to obtain sufficient board performance, it is necessary to press the fibers with a high pressure to form the fiber layer 15, which is lightweight. There was a limit to the conversion.

The present invention has been made in view of the above points, and an object of the present invention is to provide a kenaf composite board having excellent strength and surface smoothness even when formed to be lightweight, and a method for manufacturing the same. Is.

[0009]

A kenaf composite board according to claim 1 of the present invention is a kenaf composite board formed by arranging kenaf fiber layers 2 on both surfaces of a wood veneer 1 respectively. The kenaf fiber layer 2 is intertwined with each other and has a plurality of kenaf filaments 3 having a length of 20 mm or more and a thermosetting resin 4.
And the kenaf fiber layer 2 is bonded to the wood veneer 1.

The invention of claim 2 is characterized in that in the kenaf fiber layer 2 according to claim 1, the kenaf filaments 3 are oriented in one direction or in an orthogonal direction.

The invention of claim 3 is characterized in that, in claim 1, the kenaf fiber layer 2 is formed into a sheet by knitting or weaving the kenaf filaments 3.

The invention of claim 4 is characterized in that, in any one of claims 1 to 3, the wood veneer 1 has a specific gravity of 0.5 or less.

A fifth aspect of the present invention is characterized in that, in any of the first to fourth aspects, as the wood veneer 1, a poplar veneer obtained from poplar is used.

In the method for manufacturing a kenaf composite board according to claim 6 of the present invention, a water-soluble thermosetting resin 4 is added to a kenaf fiber mat 5 formed by intertwining a plurality of kenaf filaments 3 having a length of 20 mm or more. With a thermosetting resin impregnating step, a drying step of drying the kenaf fiber mat 5 impregnated with the thermosetting resin 4, and the dried kenaf fiber mat 5 are overlaid on both sides of the wood veneer 1. It is characterized by comprising a laminating step of forming the laminated body 6 by means of the above and a thermocompression molding step of heating and pressurizing the laminated body 6 to integrate them.

According to a seventh aspect of the present invention, in the drying step of the sixth aspect, the kenaf fiber mat 5 impregnated with the thermosetting resin 4 is dried until the water content is in the range of 20 to 100% by mass. It is characterized by.

The invention according to claim 8 is characterized in that, in the drying step according to claim 6 or 7, the kenaf fiber mat 5 is dried by blowing hot air having a temperature of 40 to 120 ° C. on one surface thereof. Is.

According to a ninth aspect of the invention, in the laminating step according to any of the sixth to eighth aspects, the laminate 6 composed of the wood veneer 1 and the kenaf fiber mat 5 is precompressed by applying pressure in the laminating direction. After that, the laminate 6 is heated and pressed in a thermocompression molding step.

The invention of claim 10 is based on claims 6 to 9.
In any one of the lamination steps, after the thermosetting resin is adhered to both surfaces of the wood veneer 1, the kenaf fiber mat 5 is laminated on both surfaces of the wood veneer 1 to form a laminate 6
Is formed.

The invention of claim 11 is characterized in that, in claim 10, the thermosetting resin applied to and attached to the wood veneer 1 is a high-viscosity liquid having a viscosity of 100 centipoise or more. .

The twelfth aspect of the invention is the sixth to first aspects.
In any one of 1, the wood veneer 1 is a wood veneer 1
Wood particles or fiber length 5 with a particle diameter of 1 mm or less, to which a thermosetting resin is attached, in the defective portion 7 such as voids and cracks present in
It is characterized by using a kenaf short fiber having a size of not more than mm.

Further, the invention of claim 13 is based on claims 6 to 1.
In any one of the laminating steps of 2, the wood veneer 1 is arranged with a plurality of wood veneers 1 with their end faces closely facing each other, and a thermosetting resin is adhered between the end faces of the wood veneers 1 adjacent to each other. It is characterized in that powder or kenaf short fibers having a fiber length of 5 mm or less are filled, and kenaf fiber mats 5 are laid on both sides of the wood veneers 1 arranged side by side so as to extend between the wood veneers 1. To do.

The invention of claim 14 relates to claims 6 to 1.
In any one of the stacking steps of 2, the end faces of the wood veneers 1 are formed on the inclined surfaces 9, and the end faces of the adjacent wood veneers 1 are stacked so that the inclined surfaces 9 overlap each other in the thickness direction. Are arranged such that their end faces are closely opposed to each other, and a kenaf fiber mat 5 is laid over the surfaces of both sides of the wood veneer 1 in which the kenaf fiber mats 5 are arranged. is there.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 shows an example of an embodiment of the invention of claim 1, wherein the kenaf fiber has a thermosetting resin as an adhesive and is hardened on both surfaces of a wood veneer 1 as a core layer. Layer 2 is laminated and bonded together to form a kenaf composite board. As the wood veneer 1, it is possible to use a veneer as shown in FIG. 1B obtained by thinly cutting a hardwood or a coniferous raw wood.

The kenaf fiber layer 2 can be formed by using a kenaf fiber mat 5 obtained by entangling a number of kenaf filaments 3 as shown in FIG. 1 (c). The method for producing the kenaf fiber mat 5 is not particularly limited, but a method of forming a mat by stacking a large number of kenaf filaments 3 and subjecting the kenaf filaments 3 to needle punching to entangle the kenaf filaments 3 Is common. Kenaf filament 3
Uses a fiber having a fiber length of 20 mm or more. When the fiber length is 20 mm or more, the kenaf fiber 3 can be strongly entangled by needle punching or the like, and the strength of the kenaf fiber layer 2 can be increased. Is something that can be done.
The kenaf long fiber 3 becomes stronger in entanglement as the fiber length becomes longer, and the strength can be increased. However, the practical upper limit of the fiber length is about 4 m because of easy availability. In this kenaf fiber mat 5, the kenaf filaments 3 may be non-oriented. The surface weight of the kenaf fiber mat 5 is not particularly limited as long as it can be handled, but the surface weight is preferably in the range of 100 to 800 g / m ² in view of the structure of the board and handleability of the mat.

Then, after the thermosetting resin is uniformly attached to the kenaf fiber mat 5, the kenaf fiber mat 5 is laminated on both surfaces of the wood veneer 1 and laminated by heating and molding. Thereby, the kenaf fiber layer 2 is formed from the kenaf fiber mat 5 and the kenaf fiber layer 2 is formed.
It is possible to obtain a kenaf composite board as shown in FIG. 1 (a) in which is bonded and integrated on both surfaces of the wood veneer 1. The type of thermosetting resin used as an adhesive for adhering the kenaf long fibers 3 of the kenaf fiber layer 2 to each other and for adhering the kenaf fiber layer 2 to the wood veneer 1 is a phenolic resin, a urea resin, a urea-melamine resin. Resins may be mentioned, but the present invention is not limited thereto. Further, the method of adhering the thermosetting resin to the kenaf fiber mat 5 is not particularly limited, and may be a dry method or a wet method.

In the kenaf composite board obtained as described above, the kenaf fiber layer 2 constituting the surface layer is formed by entwining kenaf filaments 3 having a fiber length of 20 mm or more and hardening them with a thermosetting resin. It has excellent surface smoothness and surface hardness, and has excellent strength performance. Here, when the surface layer is formed by a fiber layer of short fibers of about 1 to 5 mm such as softwood fibers, the short fibers do not have entanglement with each other, and therefore a specific gravity of about 0.6 is required to obtain sufficient board performance. Is necessary,
If the specific gravity is 0.55 or less, strength performance and surface hardness as a board cannot be obtained. On the other hand, the kenaf fiber layer 2 constituting the surface layer as in the present invention is composed of the kenaf fiber 3 having a fiber length of 20 mm or more, and the kenaf fiber 3 is intertwined with each other, so that the specific gravity is 0.45. In the range of 0.55 to 0.55, sufficient strength performance and surface hardness can be obtained, and in particular, the strength performance can be further increased by the wood veneer 1 serving as the core layer.

Here, the wood veneer 1 is obtained by thinly cutting the raw wood as described above, and FIG.
As shown in (b), the surface is uneven and the smoothness is poor, and defective portions 7 such as voids 7a and cracks 7b are formed during cutting.
2A, the kenaf fiber layer 2 having high strength, high hardness and high surface smoothness is formed on the surface of the wood veneer 1 as shown in FIG. 2C.
Since it is covered, the unevenness and the defective portion 7 of the wood veneer 1
Does not reduce board performance.

FIGS. 3 (a), 3 (b) and 3 (c) show an embodiment of the invention of claim 2, and FIG.
In the embodiment of (b), the kenaf fiber layer 2 is formed such that the kenaf long fibers 3 are oriented with the longitudinal directions of the fibers aligned in one direction. B Arrow layer is kenaf fiber layer 2
Shows the orientation direction of the kenaf filament 3 in
By orienting the kenaf filaments 3 in this way,
The strength in the orientation direction can be extremely increased and the dimensional stability in the orientation direction can be increased.

In the embodiment of FIG. 3 (a), the orientation direction of the kenaf filament 3 is orthogonal to the fiber direction of the wood veneer 1 (the direction in which the longitudinal direction of the wood fiber is indicated by the arrow B). The kenaf fiber layer 2 is laminated on the wood veneer 1. The strength of the wood veneer 1 is strong in the direction parallel to the fiber direction and weak in the direction orthogonal to the fiber direction, but this orthogonal direction is reinforced by the orientation of the kenaf long fibers 3 of the kenaf fiber layer 2, and in which direction It is also possible to obtain a kenaf composite board having high strength. In the embodiment of FIG. 3B, the kenaf fiber layer 2 is laminated on the wood veneer 1 so that the orientation direction of the kenaf filaments 3 is the same as the fiber direction of the wood veneer 1. is there. With this, it is possible to obtain a kenaf composite board having a characteristic that the strength is extremely high in the direction in which the orientation direction of the kenaf filaments 3 and the fiber direction of the wood veneer 1 coincide.

Further, in the embodiment shown in FIG. 3 (c), a plurality of kenaf fiber layers 2 are laminated with the orientation directions of the kenaf filaments 3 orthogonal to each other, and the kenaf fiber layers 2 are laminated on both sides of the wood veneer 1. I am doing it. Thus, the kenaf fiber layer 2
By orthogonally orienting the kenaf filaments 3 in the above direction, the strength can be increased in any direction,
A kenaf composite board having no anisotropy in any direction and high strength can be obtained. In the embodiment of FIG. 3 (c), a plurality of kenaf fiber layers 2 in which the kenaf filaments 3 are oriented in one direction are used by stacking them so that their orientation directions are orthogonal to each other. The kenaf fiber layer 2 formed by orienting in two directions whose longitudinal directions are orthogonal to each other may be used.

FIG. 4 shows an example of an embodiment of the invention of claim 3 in which the kenaf filament 3 is made up of warp threads 3a and weft threads 3.
Sheet-like kenaf fiber layer 2 made of a woven fabric woven as b
Are formed. By forming the kenaf fiber layer 2 by weaving the kenaf long fibers 3 in this way, the kenaf long fibers 3 are oriented in two directions orthogonal to each other, and the strength anisotropy disappears, and the strength is increased in any direction. It is possible to obtain a high kenaf composite board.
In addition to weaving the kenaf filament 3, the kenaf fiber layer 2 formed into a sheet by knitting the kenaf filament 3 can also be used.

In the fourth aspect of the invention, the wood veneer 1 having a specific gravity of 0.5 or less is used. By using the wood veneer 1 having a small specific gravity as described above, it is possible to further reduce the weight of the kenaf composite board. However, if the specific gravity of the wood veneer 1 is 0.5 or less, the material is often non-uniform, and as shown in FIG.
As shown in (b), defective portions 7 such as voids 7a and cracks 7b
Although unevenness such as waviness is often generated, the surface of the wood veneer 1 is covered with the kenaf fiber layer 2 having high strength, high hardness and high surface smoothness, thus achieving weight reduction. It is possible to obtain a kenaf composite board having high strength, high hardness and high surface smoothness. Although the lower limit of the specific gravity of the wood veneer 1 is not particularly limited, it is desirable that the specific gravity of the wood veneer 1 is 0.3 or more from the viewpoint of handleability.

In the invention of claim 5, the wood veneer 1 is a poplar veneer obtained from poplar. The poplar veneer has a very low specific gravity of 0.3 to 0.4, and can further reduce the weight of the kenaf composite board. However, many poplar veneers are made of non-uniform materials, and similar to FIGS. 2 (a) and 2 (b) described above, defects 7 such as voids 7a and cracks 7 and irregularities such as undulations are generated. Although it is a so-called low quality wood veneer 1,
Since the surface of the wood veneer 1 is covered with the kenaf fiber layer 2 having high strength, high hardness and high surface smoothness, kenaf having high strength, high hardness and high surface smoothness while achieving weight reduction. A composite board can be obtained. Further, since the poplar veneer is a soft material, it can be sufficiently clamped in the thermocompression molding process described later, and the adhesiveness of the interface between the wood veneer 1 and the kenaf fiber layer 2 by the poplar veneer can be enhanced. It is a thing. In this way, the specific gravity is 0.45
When it is 0.55, a kenaf composite board having high strength, high hardness and excellent surface smoothness can be obtained.

Next, a method of manufacturing the kenaf composite board according to claim 6 will be described. FIG. 5 shows an example of the embodiment. First, as shown in FIG. 5A, in a thermosetting resin impregnation step, a kenaf fiber mat 5 formed by intertwining a large number of kenaf filaments 3 is water-soluble. Impregnated with a thermosetting resin. That is, the thermosetting resin aqueous solution 18 is supplied to the impregnation tank 17, and the thermosetting resin aqueous solution 18 is supplied.
By dipping the kenaf fiber mat 5 in the kenaf fiber mat 5, the kenaf fiber mat 5 is impregnated with the thermosetting resin aqueous solution 18, and the kenaf long fibers 3 are formed on the surface or inside of the kenaf fiber mat 5.
A thermosetting resin is attached to the above in an aqueous solution state.
The kenaf fiber mat 5 impregnated with the thermosetting resin aqueous solution 18 has a water content of about 100 to 200% by mass.

Next, in the drying step, the kenaf fiber mat 5 impregnated with the thermosetting resin is dried. For example, the kenaf fiber having a high water content is obtained by uniformly blowing the room temperature air or hot air of about 40 to 120 ° C. with a blower onto the entire surface of the kenaf fiber mat 5 as shown by the arrow in FIG. The mat 5 can be dried. Kenaf fiber mat 5
The thermosetting resin can be fixed to the kenaf filaments 3 of the kenaf fiber mat 5 by drying the kenaf fiber mat 5 so that the water content becomes 100 mass% or less. When the water content of the dried kenaf fiber mat 5 is in the range of about 5 to 15% by mass, the kenaf fiber mat 3 is sufficiently dried and the thermosetting resin is fixed on the surface of the kenaf filament 3.

Next, the kenaf fiber mats 5 thus dried are laminated on both sides of the wood veneer 1 in a laminating step to form a laminate 6 as shown in FIG. 5 (c).

Then, the laminated body 6 in which the kenaf fiber mat 5 is superposed on both surfaces of the wood veneer 1 is heat-pressed in the hot-pressing step of FIG. 5 (d). That is, the laminated body 6 is set between the heating plates 20 of the hot press machine 19, and the laminated plates 6 are placed on the heating plate 20.
By heating and pressurizing the kenaf fiber mat 5 while curing the thermosetting resin, the kenaf fiber layer 2 to which the kenaf long fibers 3 are adhesively fixed by using the thermosetting resin as an adhesive is formed. It is possible to obtain a kenaf composite board having a three-layer structure in which the kenaf fiber layer 2 is bonded to both sides of the wood veneer 1 with a thermosetting resin. The heating and pressurizing conditions in this thermocompression molding step are not particularly limited, but a temperature of 150 to 180 ° C., a pressure of 1 to 5 MPa, and a pressing time of 1 to 10 minutes are suitable.

In manufacturing the kenaf composite board through the above steps, the kenaf fiber mat 5 is soaked in the uniform thermosetting resin aqueous solution 18 in the impregnation step, so that even inside the kenaf fiber mat 5. The thermosetting resin can be evenly impregnated, and the kenaf fiber mat 5 is dried in the drying step to evaporate the water content of the thermosetting resin aqueous solution 18 so that the thermosetting resin is mixed with the kenaf long fibers. 3 can be fixed uniformly. Therefore, by stacking this kenaf fiber mat 5 on both sides of the wood veneer 1 in the laminating step and heat-press molding in the thermocompression molding step, the kenaf filaments 3 are entangled and bonded and fixed with a thermosetting resin to achieve strength. The kenaf fiber layer 2 having excellent performance, surface smoothness and surface hardness can be formed, and the thermosetting resin impregnated in the kenaf fiber mat 5 can be bonded without the need to apply an adhesive to the wood veneer 1. As an agent, the kenaf fiber layer 2 can be bonded and integrated with the wood veneer 1.

Here, in the invention of claim 7, in the above drying step, the kenaf fiber mat 5 impregnated with the thermosetting resin aqueous solution 18 is dried until the water content thereof falls within the range of 20 to 100% by mass. The wood veneer 1 and the kenaf fiber mat 5 are heated and pressed in the thermocompression molding process by adjusting the drying so that the water content falls within this range, and the kenaf fiber layer 2 is applied to the wood veneer 1. It is possible to improve the adhesiveness at the time of adhering.

That is, when the water content of the kenaf fiber mat 5 dried in the drying step is 20% by mass or more, FIG.
As described above, the thermosetting resin 4 is fixed in the kenaf fiber mat 5 laminated on the wood veneer 1 in a state of containing water. When the laminated body 6 is hot pressed by the hot platen 20 in the hot pressing process, the water contained in the kenaf fiber mat 5 evaporates from the side surface of the kenaf fiber mat 5 as shown by the arrow in FIG. 6B. However, when the laminated body 6 is pressurized in this way,
Since the water content of the kenaf fiber mat 5 also evaporates through the wood veneer 1, a part of the water content of the kenaf fiber mat 5 will move toward the wood veneer 1 as it evaporates. The curable resin 4 also moves to the wood veneer 1 side. And when this phenomenon occurs,
As shown in (b), the thermosetting resin 4 in the kenaf fiber mat 5 is unevenly distributed in the vicinity of the interface of the wood veneer 1. Due to the uneven distribution of the thermosetting resin 4, the wood veneer 1 is
The adhesive performance of the kenaf fiber layer 2 with respect to is improved.

In order to sufficiently obtain such an effect of improving the adhesive performance, it is necessary that the kenaf fiber mat 5 dried in the drying step has a water content of 20% by mass or more. The higher the water content, the higher the water content. The adhesive performance is improved, and thus the water absorption thickness expansion coefficient tends to be small, but when the water absorption rate of the kenaf fiber mat 5 exceeds 100% by mass, the kenaf fiber mat 5
The water absorption rate of the kenaf fiber mat 5 is preferably 100% by mass or less because the handling efficiency of the kenaf fiber mat becomes poor and the hot pressing time in the hot pressing step becomes long and the production efficiency becomes poor.

In the eighth aspect of the invention, in the drying step, the temperature of 40% is applied to the surface of the kenaf fiber mat 5 on one side.
Drying is performed by blowing hot air of 120 ° C, and the wood veneer 1 and the kenaf fiber mat 5 are subjected to the hot pressing process.
When heat and pressure are applied to bond the kenaf fiber layer 2 to the wood veneer 1, the adhesion is improved.

That is, one side of the wet kenaf fiber mat 5 impregnated with the aqueous solution of the thermosetting resin 4 is applied to the surface of FIG.
When hot air of 40 to 120 ° C. is blown as shown by the arrow in (a), water evaporates from the surface of the kenaf fiber mat 5 with which the hot air comes into contact as shown by the arrow in FIG. 7 (b). In this way, when the water evaporates from the surface on one side of the kenaf fiber mat 5,
A phenomenon in which the thermosetting resin 4 in the form of an aqueous solution also moves to this one side surface of the kenaf fiber mat 5 occurs, and the surface of the kenaf fiber mat 5 on the side in contact with the hot air has a thermosetting property as shown in FIG. 7 (b). The resin 4 is unevenly distributed. Then, the kenaf fiber mat 5 is superposed on the wood veneer 1 on the side where the thermosetting resin 4 is unevenly distributed, and heat and pressure molding is performed in a thermocompression molding step to integrate the kenaf fiber layers 2 on both sides of the wood veneer 1. When the kenaf composite board is manufactured, the adhesive performance of the kenaf fiber layer 2 to the wood veneer 1 is improved by the thermosetting resin 4 having uneven distribution.

In order to fully obtain such an effect of improving the adhesive performance, it is necessary that the temperature of the hot air used in the drying step is 40 ° C. or higher. The higher the temperature of the hot air, the faster the evaporation rate of water and the better the adhesive performance. However, if the temperature of the hot air exceeds 120 ° C., the thermosetting resin 4 may start to harden. The temperature is preferably 120 ° C. or lower.

According to the ninth aspect of the invention, the kenaf fiber mat 5 impregnated with the aqueous thermosetting resin solution 18 is dried so that its water content is in the range of 20 to 100% by mass,
In the above laminating step, a pressure is applied in the laminating direction to the laminated body 6 made of the wood veneer 1 and the kenaf fiber mat 5 so as to be pre-pressed, and the wood veneer 1 and the kenaf fiber mat are subjected to the thermocompression molding step. When the kenaf fiber layer 2 is bonded to the wood veneer 1 by heating and pressurizing the wood 5, the adhesiveness is improved.

That is, when the water content of the kenaf fiber mat 5 laminated on the wood veneer 1 in the laminating step is 20 to 100% by mass, the thermosetting resin 4 in the kenaf fiber mat 5 exists in an aqueous solution state, For example, when the laminated body 6 is pre-pressed by passing it between the pressing rollers 22 as shown in FIG. 8, the thermosetting resin 4 in the kenaf fiber mat 5 together with the water absorbs the wood veneer 1
The wood veneer 1 adheres to the surface of the wood veneer 1 by exuding at the interface with
When manufacturing a kenaf composite board in which the kenaf fiber layers 2 are integrated on both sides of the above, the adhesion performance of the kenaf fiber layers 2 to the wood veneer 1 can be improved.

According to a tenth aspect of the invention, in the laminating step,
After the thermosetting resin is applied and adhered to both surfaces of the wood veneer 1, the kenaf fiber mats 5 are stacked on both surfaces of the wood veneer 1 to form a laminate 6. The method of attaching the thermosetting resin to the surface of the wood veneer 1 is not particularly limited, but a method of uniformly applying the thermosetting resin to the surface of the wood veneer 1 with a spray or a roll coater is suitable.

By adhering the thermosetting resin to both surfaces of the wood veneer 1 in this way, an adhesive layer of the thermosetting resin is formed between the wood veneer 1 and the kenaf fiber layer 2. The adhesiveness between the wood veneer 1 and the kenaf fiber layer 2 can be significantly improved, and the peel strength between the wood veneer 1 and the kenaf fiber layer 2 in the kenaf composite board can be significantly improved. is there. The thermosetting resin used as the adhesive is preferably a water-soluble thermosetting resin,
For example, a phenol resin, a urea resin, a urea / melamine resin can be mentioned. The amount of the thermosetting resin attached may be about 10 to 100 g / m ² , and even with such a small amount, sufficient adhesion can be improved.

According to the eleventh aspect of the present invention, the thermosetting resin is applied to the surfaces of both sides of the wood veneer 1 and attached thereto.
A high-viscosity thermosetting resin liquid having a viscosity (25 ° C.) of 100 cp or more is used. When a water-soluble thermosetting resin is applied and attached to the surface of the wood veneer 1, it has the property of penetrating from the surface of the wood veneer 1 to the inside, and it is considered that the thermosetting resin liquid with a low viscosity is used for the wood veneer. It is difficult to excessively permeate the inside of the board 1 to form an adhesive layer on the surface, and it is difficult to obtain high adhesiveness at the interface between the wood veneer 1 and the kenaf fiber layer 2. Therefore, by using a high-viscosity thermosetting resin liquid having a viscosity of 100 cp or more, penetration of the wood veneer 1 into the interior is suppressed, and a sufficient adhesive layer is formed on the surface of the wood veneer 1. In this way, the adhesiveness at the interface between the wood veneer 1 and the kenaf fiber layer 2 can be improved, and the peel strength between the wood veneer 1 and the kenaf fiber layer 2 in the kenaf composite board can be significantly improved. Is. The higher the viscosity of the thermosetting resin liquid, the greater the effect of improving the adhesiveness can be obtained, but if the viscosity is too high, the workability of the coating becomes poor and it becomes difficult to uniformly coat the liquid. The viscosity of the thermosetting resin liquid is preferably 2000 cp or less.

FIG. 9 shows an example of the embodiment of the invention of claim 12. The wood veneer 1 having a specific gravity of 0.5 or less has voids 7a and cracks 7b as shown in FIGS.
Often has a defective portion 7 such as, and especially low quality such as poplar veneer has a void 7a with a diameter of 10 mm or more.
Or a crack 7b having a width of 5 mm or more is generated. In such a case, even if the wood veneer 1 is covered with the kenaf fiber layer 2, the strength, surface hardness, surface smoothness of the kenaf composite board, The performance of the water absorption thickness expansion rate decreases.

Therefore, in the invention of claim 12, the wood veneer 1
Wood powder or fiber length 5 with a particle diameter of 1 mm or less, in which a thermosetting resin is attached to defective portions 7 such as voids 7a and cracks 7b
Filling kenaf short fibers of mm or less as the repair agent 24,
The defective portion 7 is repaired.
A kenaf composite board is manufactured in the same manner as described above using the wood veneer 1 that has been repaired. Even with such a low-quality wood veneer 1, a kenaf composite board having sufficient strength, surface hardness, surface smoothness, and water absorption thickness expansion coefficient can be obtained by using it after repairing the defective portion 7. Is something that can be done.

Wood powder with a particle size of 1 mm or less or fiber length 5 m
A water-soluble thermosetting resin is suitable as the thermosetting resin to be attached to the kenaf short fibers of m or less, and examples thereof include a phenol resin, a urea resin, and a urea-melamine resin. Further, as the wood powder, powder of any wood such as hardwood and conifer can be used,
If the particle size exceeds 1 mm, the workability of filling the defective portion 7 is deteriorated, so the particle size of the wood powder is preferably 1 mm or less. The lower limit of the particle size of the wood powder is not particularly set, but it is desirable that the particle size of the wood powder is 30 μm or more from the viewpoint of handleability and the like. If the fiber length of the kenaf short fibers exceeds 5 mm, the workability of filling the defective portion 7 is deteriorated. Therefore, the fiber length of the kenaf short fibers is preferably 5 mm or less. Although the lower limit of the fiber length of the kenaf staple fibers is not particularly set, it is desirable that the fiber length of the kenaf staple fibers is 50 μm mm or more from the viewpoint of handleability and the like.

FIG. 10 shows an example of an embodiment of the invention of claim 13 in which a plurality of wood veneers 1 and their end faces are closely opposed to each other in the above laminating step. Arranged as shown in a), the kenaf fiber mats 5 are arranged on both sides of the arranged plurality of wood veneers 1 so as to extend between the wood veneers 1 as shown in FIG. 10B. Then, the kenaf fiber layer 2 is bonded and integrated to the surface of the core layer composed of a plurality of wood veneers 1 as shown in FIG. It is designed to manufacture a composite board.

The wood veneer 1, particularly the low-quality wood veneer 1 having a specific gravity of 0.5 or less, has a limit in the size in the direction perpendicular to the fiber direction, for example, 4 × 8 shaku (about 1. 2 x approx. 2.4 m), it is necessary to arrange a plurality of wood veneers 1 side by side to form a core layer, and in the case of a wood veneer 1 obtained from a small diameter tree such as poplar, 4 x In order to make it 8 shaku, it is necessary to arrange three wood veneers 1. When a plurality of wood veneers 1 are arranged side by side in this way, a kenaf fiber mat 5 is arranged between the wood veneers 1 and heat-press molded in a thermocompression molding process to obtain each wood veneer. There is a possibility that the veneer 1 may shift and a gap may be formed at the joint between the end faces of the adjacent veneer 1 which are adjacent to each other. If this gap is about 1 mm or more, the manufactured kenaf composite board is adversely affected in strength, surface hardness, surface smoothness, and water absorption thickness expansion coefficient.

Therefore, according to the thirteenth aspect of the present invention, wood powder having a particle diameter of 1 mm or less or a fiber length of 5 with a thermosetting resin adhered between the end faces of the adjacent wood veneers 1 arranged in close proximity and facing each other.
A kenaf short fiber having a diameter of mm or less is used as the filler 25 in FIG.
The filling is performed as in (c), and the adjacent wood veneers 1 are joined with this filler 25. Therefore, when a plurality of wood veneers 1 are arranged side by side between the wood veneers 1, the kenaf fiber mat 5 is arranged, and when the kenaf fiber mat 5 is heated and pressed in the thermopressing step, It is possible to prevent the veneer 1 from shifting and to prevent a gap from being formed at the joint between the facing end faces of the adjacent veneer woods 1, and the strength, surface hardness, surface smoothness, and water absorption thickness expansion coefficient are sufficient. It is possible to obtain a kenaf composite board with excellent performance.

Wood powder having a particle size of 1 mm or less or a fiber length of 5 m
A water-soluble thermosetting resin is suitable as the thermosetting resin to be attached to the kenaf short fibers of m or less, and examples thereof include a phenol resin, a urea resin, and a urea-melamine resin. Further, as the wood powder, powder of any wood such as hardwood and conifer can be used,
If the particle size exceeds 1 mm, the workability of filling the joint between the wood veneers 1 deteriorates, so the particle size of the wood powder is preferably 1 mm or less. The lower limit of the particle size of the wood powder is not particularly set, but it is desirable that the particle size of the wood powder is 30 μm or more from the viewpoint of handleability and the like. The fiber length of kenaf staple fiber is 5 mm
If it exceeds, the workability of filling the joint between the wood veneers 1 deteriorates. Therefore, the fiber length of the kenaf short fibers is preferably 5 mm or less. Although the lower limit of the fiber length of the kenaf staple fibers is not particularly set, it is desirable that the fiber length of the kenaf staple fibers is 50 μm or more from the viewpoint of handleability and the like.

FIG. 11 shows an example of an embodiment of the invention of claim 14 in which the end portion of the wood veneer 1 is obliquely cut in the thickness direction to obtain an end surface as shown in FIG. 11 (a). Is formed on the inclined surface 9. Then, in the laminating step, when arranging a plurality of wood veneers 1 with their end faces closely facing each other, the end faces of the adjacent wood veneers 1 are arranged so that the inclined surfaces 9 overlap each other in the thickness direction. Has been placed.
That is, as shown in FIG. 11 (b), adjacent wood veneers 1
By arranging the inclined surfaces 9 of the opposite end portions of the two so as to incline in mutually opposite directions, it is possible to make the inclined surfaces 9 overlap the end surfaces of the adjacent wood veneer 1 in the thickness direction. Is. Then, as shown in FIG. 11 (b), kenaf fiber mats 5 are arranged on both sides of the plurality of arranged wood veneers 1 so as to extend between the wood veneers 1, and the kenaf fiber mats 5 are hot pressed. Even if the wood veneers 1 are slightly misaligned during the hot pressing in the molding process, the seams of the adjacent wood veneers 1 are inclined surfaces 9 and 9.
11 can be maintained in a state of being vertically overlapped with each other.
As shown in (c), an integrated kenaf composite board in which the kenaf fiber layers 2 are bonded to both surfaces of the wood veneer 1 without producing a gap at the joint between the facing end faces of the adjacent wood veneers 1 is manufactured. Which can be used for strength, surface hardness,
It is possible to obtain a kenaf composite board having sufficient performances of surface smoothness and water absorption thickness expansion coefficient.

[0059]

EXAMPLES Next, the present invention will be specifically described with reference to examples.

Example 1 A large number of kenaf bast long fibers having a fiber diameter of 50 to 600 μm and a fiber length of 20 to 100 mm were piled up and collected, and needle-punched to obtain kenaf long fibers intertwined with each other. A unidirectionally oriented kenaf fiber mat was prepared. The mat surface weight of this kenaf fiber mat was 400 g / m ² .

Next, the kenaf fiber mat was dipped in an aqueous solution of phenol resin having a solid content of 25% by mass for 10 seconds,
The aqueous phenol resin solution was applied uniformly to the kenaf filaments of the kenaf fiber mat by applying a roller squeezer. The water content of the kenaf fiber mat impregnated with the aqueous phenol resin solution was 165% by mass.

Next, the surfaces of both sides of the kenaf fiber mat impregnated with the aqueous phenol resin solution are blown with normal temperature air obtained by a blower blower to bring them into contact with each other, thereby reducing the water content to 20% by mass, and By blowing hot air at a temperature of 80 ° C. and bringing them into contact with each other, the water content was reduced to 10% by mass, and drying was performed.

Next, the dried kenaf fiber mats were laminated on both sides of the poplar veneer so that the fiber direction of the poplar veneer and the orientation direction of the kenaf filament were orthogonal to each other, and this was hot pressed. Using a press machine, heating plate temperature 160 ℃,
The kenaf composite board as shown in FIG. 3 (a) was obtained by thermocompression molding under a molding pressure of 3 MPa and a molding time of 5 minutes. The resin content of the obtained kenaf composite board is 2
It was 5% by mass.

(Example 2) A kenaf fiber mat was produced in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber diameter of 50 to 600 µm and a fiber length of 100 to 200 mm were used. Thereafter, in the same manner as in Example 1, a kenaf composite board as shown in FIG. 3 (a) was obtained.

Example 3 A surface weight of 350 was obtained in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber diameter of 50 to 600 μm and a fiber length of 200 to 2000 mm were used.
A kenaf fiber mat of g / m ² was produced, and thereafter, in the same manner as in Example 1, a kenaf composite board as shown in FIG. 3 (a) was obtained.

Example 4 A surface weight of 380 was obtained in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber diameter of 50 to 600 μm and a fiber length of 200 to 2000 mm were used.
A kenaf fiber mat of g / m ² was produced, and thereafter, in the same manner as in Example 1, a kenaf composite board as shown in FIG. 3 (a) was obtained.

Example 5 A surface weight of 400 was obtained in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber diameter of 50 to 600 μm and a fiber length of 200 to 2000 mm were used.
A kenaf fiber mat of g / m ² was produced, and thereafter, in the same manner as in Example 1, a kenaf composite board as shown in FIG. 3 (a) was obtained.

Example 6 A surface weight of 440 was obtained in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber diameter of 50 to 600 μm and a fiber length of 200 to 2000 mm were used.
A kenaf fiber mat of g / m ² was produced, and thereafter, in the same manner as in Example 1, a kenaf composite board as shown in FIG. 3 (a) was obtained.

Example 7 A surface weight of 480 was obtained in the same manner as in Example 1 except that kenaf bast long fibers having a fiber diameter of 50 to 600 μm and a fiber length of 200 to 2000 mm were used.
A kenaf fiber mat of g / m ² was produced, and thereafter, in the same manner as in Example 1, a kenaf composite board as shown in FIG. 3 (a) was obtained.

Example 8 A kenaf fiber mat having a surface weight of 400 g / m ² was prepared in the same manner as in Example 1 using kenaf bast long fibers having a fiber diameter of 50 to 600 μm and a fiber length of 200 to 2000 mm. After that, the kenaf fiber mat was laminated on the poplar veneer so that the fiber direction of the poplar veneer and the orientation direction of the kenaf long fibers were the same direction. A kenaf composite board as shown in (b) was obtained.

Example 9 Using kenaf bast long fibers having a fiber diameter of 50 to 600 μm and a fiber length of 200 to 2000 mm, a kenaf fiber mat having a two-layer structure in which the fiber directions of the kenaf long fibers were orthogonal to each other was prepared. This kenaf fiber mat had a surface weight of 400 g / m ² . After that, instead of the phenol resin aqueous solution, a urea resin aqueous solution having a solid content of 25 mass% was used in the same manner as in Example 1,
A kenaf composite board as shown in FIG. 3 (c) was obtained.

Example 10 Fiber diameter 50 to 600 μm,
A long fiber of kenaf bast having a fiber length of 200 to 2000 mm was used as a warp yarn and a weft yarn, and was woven to prepare a kenaf fiber mat as a sheet of woven fabric having a surface weight of 400 g / m ² . Then, a kenaf composite board as shown in FIG. 4 was obtained in the same manner as in Example 1 except that a urea / melamine resin aqueous solution having a solid content of 25 mass% was used instead of the phenol resin aqueous solution. .

Example 11 Fiber diameter 50 to 600 μm,
A surface weight of 380 was obtained in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber length of 200 to 2000 mm were used.
A g / m ² kenaf fiber mat was prepared. And, except that the softwood veneer is used as the wood veneer, Example 1
In the same manner as described above, a kenaf composite board as shown in FIG. 3 (a) was obtained.

Example 12 Fiber diameter 50 to 600 μm,
A surface weight of 400 in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber length of 200 to 2000 mm were used.
A g / m ² kenaf fiber mat was prepared. Then, the kenaf fiber mat impregnated with the aqueous phenol resin solution was dried so that the water content was 21% by mass, and the lamination and thermocompression molding were carried out in the same manner as in Example 1 except that FIG.
A kenaf composite board as shown in (a) was obtained.

(Example 13) Fiber diameter 50 to 600 μm,
A surface weight of 400 in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber length of 200 to 2000 mm were used.
A g / m ² kenaf fiber mat was prepared. Then, the kenaf fiber mat impregnated with the aqueous phenol resin solution was dried to have a water content of 50% by mass, and laminated and thermocompression-molded in the same manner as in Example 1, except that FIG.
A kenaf composite board as shown in (a) was obtained. (Example 14) Fiber diameter 50 to 600 μm, fiber length 200
A kenaf fiber mat having a surface weight of 400 g / m ² was produced in the same manner as in Example 1 except that long fibers of kenaf bast of ˜2000 mm were used. Then, the kenaf fiber mat impregnated with the aqueous phenol resin solution was dried so that the water content was 100% by mass, and the lamination and thermocompression molding were performed. The kenaf composite board as shown in FIG. (Example 15) Fiber diameter 50 to 600 μm, fiber length 200
A kenaf fiber mat having a surface weight of 400 g / m ² was produced in the same manner as in Example 1 except that long fibers of kenaf bast of ˜2000 mm were used. When the kenaf fiber mat impregnated with the aqueous phenol resin solution is dried, only one surface of the kenaf fiber mat is contacted by blowing the room temperature air obtained by a blower blower and the hot air having a temperature of 80 ° C. to bring the moisture content into contact. A kenaf composite board as shown in FIG. 3A was obtained in the same manner as in Example 1 except that the content was reduced to 50% by mass. (Example 16) Fiber diameter 50 to 600 μm, fiber length 200
A kenaf fiber mat having a surface weight of 400 g / m ² was produced in the same manner as in Example 1 except that long fibers of kenaf bast of ˜2000 mm were used. When the kenaf fiber mat impregnated with the aqueous phenol resin solution is dried, only one surface of the kenaf fiber mat is contacted by blowing the room temperature air obtained by a blower blower and the hot air having a temperature of 80 ° C. to bring the moisture content into contact. The kenaf composite as shown in FIG. 3 (a) was carried out in the same manner as in Example 1 except that the pressure was reduced to 50% by mass, and then pre-pressing was performed through a pressing roller as shown in FIG. Got the board.

(Example 17) Fiber diameter 50 to 600 μm,
A surface weight of 400 in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber length of 200 to 2000 mm were used.
A g / m ² kenaf fiber mat was prepared. Then, the kenaf fiber mat impregnated with the aqueous phenol resin solution is dried to a water content of 40% by mass, and in the laminating step, 50 g / m ² of urea resin having a viscosity of 500 cp is applied to both surfaces of the poplar veneer with a roll coater. 3 (a) in the same manner as in Example 1 except that the coating amount of 1 was used.
A kenaf composite board as shown in was obtained.

Example 18 Fiber diameter 50 to 600 μm,
A surface weight of 400 in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber length of 200 to 2000 mm were used.
A g / m ² kenaf fiber mat was prepared. Then, the kenaf fiber mat impregnated with the aqueous phenol resin solution is dried to have a water content of 35% by mass, and in the laminating step, 50 g / m ² of a phenol resin having a viscosity of 100 cp is sprayed on both surfaces of the poplar veneer. A kenaf composite board as shown in FIG. 3 (a) was obtained in the same manner as in Example 1 except that the coating amount was used.

Example 19 Fiber diameter 50 to 600 μm,
A surface weight of 400 in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber length of 200 to 2000 mm were used.
A g / m ² kenaf fiber mat was prepared. Then, the kenaf fiber mat impregnated with the phenol resin aqueous solution is dried to a water content of 35% by mass, and a fiber length of 5 m is added to a portion of the poplar veneer where voids or cracks are formed in the lamination process.
3 was carried out in the same manner as in Example 1 except that a kenaf short fiber of m or less was filled with a repairing agent prepared by adhering 10% by mass of a phenol resin by spray coating.
A kenaf composite board as shown in (a) was obtained.

Example 20 Fiber diameter 50 to 600 μm,
A surface weight of 400 in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber length of 200 to 2000 mm were used.
A g / m ² kenaf fiber mat was prepared. Then, the kenaf fiber mat impregnated with the aqueous phenol resin solution is dried to have a water content of 38% by mass, and in the laminating step, a plurality of poplar veneers are spliced together, and wood powder having a particle diameter of 1 mm or less is mixed with urea resin. 3 was carried out in the same manner as in Example 1 except that a filler prepared by applying 10 mass% by spray coating was filled between the end faces of the seam.
A kenaf composite board as shown in (a) was obtained.

(Example 21) Fiber diameter 50 to 600 μm,
A surface weight of 400 in the same manner as in Example 1 except that long fibers of kenaf bast having a fiber length of 200 to 2000 mm were used.
A g / m ² kenaf fiber mat was prepared. Then, the kenaf fiber mat impregnated with the aqueous phenol resin solution was dried to have a water content of 36% by mass, and in the laminating step, the end portion of the poplar veneer was cut diagonally and the inclined surfaces were piled up and down. A kenaf composite board as shown in FIG. 3 (a) was obtained in the same manner as in Example 1 except that a plurality of spliced boards were used in this state.

Comparative Example 1 A kenaf bast long fiber having a fiber diameter of 50 to 600 μm and a fiber length of 200 to 2000 mm was coated with a phenol resin adhesive in an amount of 25% by mass based on the absolute dry weight of the fiber.
A kenaf fiber board was obtained by spray coating and producing a kenaf fiber mat using the kenaf filaments, followed by heat-press molding under the same conditions as in Example 1.

Comparative Example 2 A softwood short fiber having a fiber length of 1 to 5 mm was spray-coated with a phenol resin adhesive in an amount of 25% by mass based on the absolute dry weight of the fiber, and a fiber mat was prepared using the softwood short fiber. . Then, a softwood composite board as shown in FIG. 12 was obtained by laminating fiber mats on both surfaces of a softwood veneer coated with a phenol resin adhesive with a roll coater and heat-pressing the same under the same conditions as in Example 1. Obtained.

Comparative Example 3 A lauan plywood was used for comparison.

(Comparative Example 4) MDF was used for comparison.

Comparative Example 5 A particle board was used for comparison.

Comparative Example 6 A softwood composite board as shown in FIG. 12 was obtained in the same manner as in Comparative Example 2 except that the poplar veneer was used as the core layer instead of the softwood veneer.

Tables 1 and 2 collectively show the board configurations and manufacturing conditions of Examples 1 to 21 and Comparative Examples 1 to 6 described above.

[0088]

[Table 1]

[0089]

[Table 2]

Next, regarding each of the boards obtained in Examples 1 to 21 and Comparative Examples 1 to 6, flexural strength, flexural Young's modulus, peel strength, and water expansion thickness expansion coefficient were measured according to JIS A 5906 (medium fiber board. ), The method specified in JIS A 5905 (fiber board) is used, and when the load of 300 N is applied to the board surface using a hard ball having a diameter of 10 mm, the amount of hard ball compression dent is measured to evaluate the surface hardness. did. The results are shown in Table 3.

[0091]

[Table 3]

As can be seen from Table 3, the kenaf composite board of each Example is the kenaf fiberboard of Comparative Example 1 or Comparative Examples 2 and 6.
In comparison with the softwood composite board of No. 3 and the particle board of Comparative Example 6, the strength performance was high while having a low specific gravity of 0.6 or less. Further, the kenaf composite boards of the respective examples have the same peel strength as the plywood of Comparative Example 3 and have sufficient interlayer adhesion strength as a board, and moreover, regarding the thickness expansion coefficient when absorbing water, Since sufficient adhesive strength was obtained, it had a performance equal to or higher than that of the plywood of Comparative Example 3. Furthermore, the kenaf composite board of each example had a surface hardness performance equal to or higher than that of the MDF of Comparative Example 4.

[0093]

As described above, the kenaf composite board according to claim 1 of the present invention is a kenaf composite board formed by disposing kenaf fiber layers on both surfaces of a wood veneer. Layers intertwined with each other 20 mm long
Since the kenaf fiber layer is formed of a large number of the above-mentioned kenaf filaments and thermosetting resin and the kenaf fiber layer is bonded to the wood veneer, the kenaf fiber layer constituting the surface layer has a fiber length of 20.
It is formed by entwining kenaf filaments of mm or more and solidifying them with a thermosetting resin, and has excellent strength and surface smoothness even when formed into a light weight. It also has excellent adhesion between layers and has excellent water resistance.

According to the second aspect of the invention, the kenaf fiber layers have the kenaf filaments oriented in one direction or in the orthogonal direction. Therefore, depending on the orientation of the kenaf filaments, strength performance in the orientation direction and dimensional stability performance during water absorption etc. Is excellent.

According to the third aspect of the invention, the kenaf fiber layer is formed into a sheet by knitting or weaving kenaf filaments. Therefore, there is no anisotropy and strength and dimensional stability in all directions are obtained. Can be obtained high. In addition, the kenaf fiber layer has kenaf filaments entwined in the thickness direction, and has excellent performance in terms of water absorption thickness expansion coefficient.

Further, the invention of claim 4 is characterized in that the wood veneer has a specific gravity of 0.5 or less, and even if the wood veneer has such a low specific gravity, it is of low quality. The kenaf fiber layer formed as the surface layer makes it possible to obtain high strength, high hardness, and excellent surface smoothness while making use of low specific gravity.

Further, the invention of claim 5 is a wood veneer,
It is characterized by using poplar veneer obtained from poplar, even if the specific gravity of wood veneer is such low and low quality poplar veneer, by the kenaf fiber layer formed as a surface layer By utilizing the characteristics of the poplar veneer having a low specific gravity, it is possible to obtain high strength, high hardness, and excellent surface smoothness.

In the method for producing a kenaf composite board according to claim 6 of the present invention, a kenaf fiber mat formed by intertwining a large number of kenaf filaments having a length of 20 mm or more is impregnated with a water-soluble thermosetting resin. Thermosetting resin impregnation step, drying step of drying the kenaf fiber mat impregnated with the thermosetting resin, and stacking the dried kenaf fiber mat on both sides of the wood veneer to form a laminate It is characterized by comprising a process and a thermocompression molding process in which the laminate is heated and pressed to be integrated, and the thermosetting resin can be uniformly penetrated and fixed even inside the kenaf fiber mat. It is possible to form a kenaf fiber layer having excellent strength performance and surface hardness and to bond the kenaf fiber layer to a wood veneer using a thermosetting resin impregnated in the kenaf fiber layer. Can, in which it is possible to obtain an excellent kenaf composite board interlayer adhesion.

Further, in the invention of claim 7, in the drying step, the kenaf fiber mat impregnated with the thermosetting resin is dried until the water content is in the range of 20 to 100% by mass. With the evaporation of water when heating the kenaf fiber mat in the molding process, it is possible to move the thermosetting resin so that a large amount of it exists at the interface with the wood veneer.
The interlayer adhesion between the wood veneer and the kenaf fiber layer can be enhanced.

[0100] According to the invention of claim 8, in the drying step, the temperature of 40 to 120 is applied to the surface of one side of the kenaf fiber mat.
Since drying is performed by blowing hot air of ℃, it is possible to make a large amount of thermosetting resin present on the surface of the kenaf fiber mat on the side where the hot air comes into contact, and the wood veneer and kenaf fiber layer It is possible to improve the inter-layer adhesiveness.

According to a ninth aspect of the present invention, in the laminating step, pressure is applied in the laminating direction to the laminated body composed of the wood veneer and the kenaf fiber mat to pre-compress, and then the laminated body is heated in the thermocompression molding step. Since the pressure is applied, a large amount of thermosetting resin can be present on the surface of the kenaf fiber mat, and the interlayer adhesion between the wood veneer and the kenaf fiber layer can be enhanced.

According to a tenth aspect of the present invention, in the laminating step, a thermosetting resin is adhered to both surfaces of the wood veneer, and then a kenaf fiber mat is laminated on each surface of the wood veneer to form a laminate. Since it is formed, it is possible to enhance the adhesiveness of the interface between the wood veneer and the kenaf fiber layer,
It is possible to improve the delamination property and the water absorption thickness expansion coefficient of the kenaf composite board.

In the eleventh aspect of the present invention, since the thermosetting resin applied to the wood veneer to be applied is a high-viscosity liquid having a viscosity of 100 centipoise or more, the thermosetting resin penetrates into the wood veneer. Can be prevented from being absorbed,
It is possible to obtain high adhesiveness at the interface between the wood veneer and the kenaf fiber layer.

Further, the invention of claim 12 is, as a wood veneer, a defect part such as a void or a crack existing in the wood veneer,
Since wood powder having a particle diameter of 1 mm or less with a thermosetting resin or short kenaf fibers having a fiber length of 5 mm or less is used, it is possible to use it after repairing the defective portion of the wood veneer. Therefore, it is possible to prevent the performance and quality of the board from being deteriorated by the defect of the wood veneer.

According to a thirteenth aspect of the present invention, in the laminating step, a plurality of wood veneers are arranged with their end faces closely opposed to each other, and a thermosetting resin is adhered between the end faces of the adjacent wood veneers. 1 mm or less of wood powder or kenaf short fibers having a fiber length of 5 mm or less was filled, and kenaf fiber mats were laid on both sides of the wood veneers arranged side by side between the wood veneers. Therefore, when multiple wood veneers are used in succession, it is possible to prevent the seams between the wood veneers from becoming defects such as gaps, and the defects of the seams of the wood veneers reduce the board performance and quality. It can prevent that.

According to a fourteenth aspect of the present invention, in the laminating step, the end faces of the wood veneers are formed into inclined surfaces, and the end faces of the adjacent wood veneers are formed into a plurality of wood single plates so that the inclined surfaces overlap in the thickness direction. The boards are arranged so that their end faces are closely opposed to each other, and the kenaf fiber mat is laid on both sides of the wood veneers arranged side by side so that the kenaf fiber mat is overlapped. It is possible to prevent the seam of the veneer from becoming a defect such as a gap, and prevent the deterioration of the board performance and quality due to the defect of the seam of the wood veneer.

[Brief description of drawings]

FIG. 1 shows an example of an embodiment of a kenaf composite board according to the present invention, where (a) is a perspective view of a kenaf composite board, (b) is a perspective view of a wood veneer, and (c) is kenaf. It is a perspective view of a fiber mat.

FIG. 2 shows an example of the above embodiment,
(A) is a cross-sectional view of a wood veneer, (b) is a perspective view of the wood veneer, and (c) is a cross-sectional view of the wood veneer and the kenaf fiber layer of the kenaf composite board.

FIG. 3 shows an example of the above embodiment,
(A), (b), (c) is a partially broken perspective view.

FIG. 4 is a perspective view showing an example of the same embodiment.

FIG. 5 shows an example of an embodiment of a method for manufacturing a kenaf composite board according to the present invention, including (a), (b),
(C), (d) is a perspective view of each process, respectively.

FIG. 6 shows an example of the above embodiment,
(A), (b) is sectional drawing, respectively.

FIG. 7 shows an example of the above embodiment,
(A), (b) is sectional drawing, respectively.

FIG. 8 is a cross-sectional view showing an example of the above embodiment.

FIG. 9 is a perspective view of an example of the above embodiment.

FIG. 10 shows an example of the above embodiment,
(A) is a perspective view of a wood veneer, (b) is sectional drawing in a lamination process, (c) is a partial sectional view of a kenaf composite board.

FIG. 11 shows an example of the above embodiment,
(A) is sectional drawing of a wood veneer, (b) is sectional drawing in a lamination process, (c) is sectional drawing of a kenaf composite board.

FIG. 12 is a perspective view of a conventional example.

[Explanation of symbols]

1 wood veneer 2 Kenaf fiber layer 3 Kenaf filament 4 Thermosetting resin 5 Kenaf fiber mat 6 laminate 7 defective part 9 inclined surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Onishi             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Liu Wenhai             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company F term (reference) 2B200 AA01 AA07 BA03 BA11 BB01                       BB04 BB06 BB07 BB15 CA11                       DA04 EA06 EE13 EF11 FA24                       FA31 HA03                 2B250 AA01 AA05 AA06 AA09 AA13                       BA05 BA06 CA11 DA04 EA02                       EA13 FA21 FA31 FA37 HA01                 2B260 AA03 AA12 BA01 BA07 BA19                       CB01 CB04 CD02 CD03 CD04                       CD06 DA01 DA17 DD02 EA05                       EB02 EB06 EB19 EB21                 4F100 AJ02A AJ02C AK01A AK01C                       AP01B BA03 BA06 BA10A                       BA10C DG01A DG01C EJ202                       EJ422 EJ82A EJ82C EJ821                       EJ861 GB07 JA02 JA13B                       JB13A JB13C JK06 JK14                       JL04 JL16 YY00B                 4J040 EB031 EB111 EB131 JB02                       KA04 LA06 MA08 MA09 MB02                       MB09 NA12 NA13

Claims (14)

[Claims] 1. A kenaf composite board formed by arranging kenaf fiber layers on both surfaces of a wood veneer.
The kenaf composite layer is characterized in that the kenaf fiber layer is formed of a plurality of kenaf filaments having a length of 20 mm or more intertwined with each other and a thermosetting resin, and the kenaf fiber layer is bonded to a wood veneer. board. 2. The kenaf composite board according to claim 1, wherein the kenaf fiber layer is one in which the kenaf filaments are oriented in one direction or an orthogonal direction. 3. The kenaf composite board according to claim 1, wherein the kenaf fiber layer is formed into a sheet by knitting or weaving kenaf filaments. 4. The kenaf composite board according to claim 1, wherein the wood veneer has a specific gravity of 0.5 or less. 5. The kenaf composite board according to claim 1, wherein a poplar veneer obtained from poplar is used as the wood veneer. 6. A thermosetting resin impregnation step of impregnating a water-soluble thermosetting resin into a kenaf fiber mat formed by intertwining a plurality of kenaf long fibers having a length of 20 mm or more, and impregnating with a thermosetting resin. A drying process for drying the dried kenaf fiber mat, a laminating process for laminating the dried kenaf fiber mat on the surfaces of both sides of the wood veneer to form a laminated body, and heat for pressing and laminating the laminated body. A method for producing a kenaf composite board, comprising a pressure forming step. 7. The water content of the kenaf fiber mat impregnated with the thermosetting resin in the drying step is 20 to 100% by mass.
The method for producing a kenaf composite board according to claim 6, wherein the kenaf composite board is dried until it falls within the range. 8. The method for producing a kenaf composite board according to claim 6 or 7, wherein in the drying step, the kenaf fiber mat is dried by blowing hot air having a temperature of 40 to 120 ° C. on one surface of the mat. . 9. The laminating step comprises applying a pressure in a laminating direction to a laminated body made of a wood veneer and a kenaf fiber mat to pre-compress the laminated body, and then heating and pressing the laminated body in a thermocompression molding step. The method for manufacturing a kenaf composite board according to claim 6, 10. In the laminating step, a thermosetting resin is adhered to both surfaces of the wood veneer, and then a kenaf fiber mat is laminated on both surfaces of the wood veneer to form a laminate. The method for manufacturing a kenaf composite board according to any one of claims 6 to 9. 11. The method for producing a kenaf composite board according to claim 10, wherein the thermosetting resin applied to and attached to the wood veneer is a high-viscosity liquid having a viscosity of 100 centipoise or more. 12. A wood veneer is wood powder having a particle size of 1 mm or less or a kenaf short fiber having a fiber length of 5 mm or less, to which a thermosetting resin is attached to a defective portion such as a void or a crack existing in the wood veneer. The method for producing a kenaf composite board according to any one of claims 6 to 11, characterized in that a filled one is used. 13. A wood powder having a particle diameter of 1 mm or less, wherein a plurality of wood veneers are arranged with their end faces closely opposed to each other and a thermosetting resin is adhered between the end faces of the adjacent wood veneers in the laminating step. 7. A kenaf fiber mat is filled with short kenaf fibers having a fiber length of 5 mm or less, and a kenaf fiber mat is laid over both surfaces of the plurality of wood veneers so as to extend between the wood veneers. 13. The method for producing a kenaf composite board according to any one of 12. 14. In the laminating step, the end surfaces of the wood veneers are formed into inclined surfaces, and the end surfaces of the adjacent wood veneers are brought close to each other so that the inclined surfaces overlap in the thickness direction. 13. The kenaf fiber mat is arranged so as to face each other, and the kenaf fiber mat is laid on both sides of the plurality of wood veneers so as to straddle the wood veneers. Method for manufacturing kenaf composite board.