JP2003127156A - Method for producing fibrous building plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a fibrous building plate excellent in dimensional stability and adhesion. SOLUTION: In a method for producing the fibrous the building plate, a mixture in which a resin binder is mixed with vegetable fibers is hot press- molded. The resin binder is resin fibers having core-sheath structure, the melting point of the sheath of the core-sheath fibers is lower than that of the core, and a hot press-molding temperature is adjusted to be lower than the melting point of the core of the core-sheath fibers to melt the sheath.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber-type building board by thermocompression molding a mixture of a vegetable fiber and a resin binder.

[0002]

2. Description of the Related Art In general, the drawbacks of plant fiber (including woody material) materials are that they have relatively large water absorption and moisture absorption, large dimensional changes, and large anisotropy such as strength and dimensional changes. There is also a problem that some materials are soft and easily scratched.

In order to solve this drawback, wood is finely crushed into chips and fibers, and a resin (mainly a thermosetting resin such as phenol, melamine,
(Urethane, etc.) is mixed to form a fibrous building board by thermocompression molding, which is used in large quantities as a substrate for interior materials for houses.

Most of these materials are put on the market as flat products, and when they are combined with other materials, a separate adhesive is required. In addition, there is also a drawback that cutting is required when processing a shape having a complicated radius shape.

It is possible to use a mat-like material before thermocompression curing (chips coated with resin) to thermocompress it into a complicated shape. In addition, compared with general wood processing, there are problems such as the need for high pressure and high temperature, and the application to products was limited.

On the other hand, in order to form a complicated shape, a resin binder (mainly a thermoplastic resin fiber,
Alternatively, it has been conventionally practiced to form a fiber board having a complicated shape by mixing a resin powder) and forming a mat (fiber mat) having a relatively low density (fiber mat) to form an interior member for an automobile. It has been.

In general, in order to suppress the dimensional change due to water absorption of the fiber board, the resin is impregnated to the inside to reduce the water absorption rate, and the mixing ratio of the vegetable fiber in the molded product causing the dimensional change is set. Reduction is an effective means.

When the molded fiber board is compounded with another material (particularly when a water-soluble adhesive is used), the mixing ratio of the adhesive and the plant fiber having good wettability is naturally increased to increase the fiber board. It is preferable to reduce the resin ratio on the surface.

Since the resin used in the latter method of molding the fiber-based board is in a fiber state or solid at room temperature, the melt viscosity of the resin is high even at a high temperature and it is difficult to enter the inside of the plant fiber. Therefore, as compared with the case of forming the fiber board by using the liquid resin as in the former method, the dimensional stability becomes worse at the same resin mixing ratio. Also, when the resin mixing ratio is increased, the dimensional change rate decreases, but when the fiber board is bonded to a substrate such as a surface decorative material (wood material or resin sheet) (especially when a water-soluble resin is used) There was a problem of poor adhesion.

Further, when only the thermoplastic resin is used as the binder, the whole is melted at the time of heat molding, the binding force between the plant fibers is lowered, and the spring back of the plant fibers cannot be suppressed, so that the hot press molding and the cold press molding are performed. Hot combining
Cold molding is required, which causes a complicated process.

Further, thermocompression molding (formation of the fiber board) and bonding press (bonding of the formed fiber board and the base material).
In the case of simultaneously performing and, the pressing temperature is a pasting temperature (100 ° C. to 160 ° C.) that is used in general wood processing.
If it is not equal to (° C), there is a problem that remarkable warping and cracking occur.

[0012]

The present invention has been made in view of the above points, and is a method for producing a fiber-based building board capable of producing a fiber-based building board excellent in dimensional stability and adhesiveness. The challenge is to provide.

[0013]

In order to solve the above problems, a method for manufacturing a fiber-based building board according to the present invention is to manufacture a fiber-based building board by thermocompression molding a mixture of a vegetable fiber and a resin binder. In the method, the resin binder is a resin fiber having a core-sheath structure, the melting point of the sheath of the core-sheath fiber is lower than the melting point of the core, and the thermoforming temperature is lower than the melting point of the core of the core-sheath fiber. In addition, the temperature is set to a temperature at which the sheath can be melted. By adopting such a method,
By heating and pressing near the melting point of the sheath, the sheath of the core-sheath fiber is melted in the entire region and the fibers are bonded to each other at the portion where the plant fiber, the core-sheath fiber and the core-sheath fiber intersect with each other, It is possible to form a fiber-based building board that is made of a fiber-based board that is difficult to change in size as a whole. Further, since the amount of resin on the surface is reduced, the adhesiveness at the time of adhering the fiber board to the substrate is also improved. Here, the melting point of the sheath is preferably 110 ° C to 150 ° C.

In addition to the plant fiber and the resin binder, it is preferable to further mix a thermosetting resin into a mixture. By adopting such a method, the thermosetting resin can reduce the springback of the fiber-based building board made of the fiber-based board and improve the surface hardness of the fiber board.

When the mixture is hot-pressed, it is preferable that the mixture is laminated with the base material and laminated with the base material. By adopting such a method, it is possible to simultaneously laminate and integrate the fiber board and the base material, which are formed simultaneously with the molding of the fiber board by thermocompression molding of the fiber mat.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on embodiments.

In producing a fiber-type building board by thermocompression molding a mixture of a vegetable fiber and a resin binder, the present invention is characterized in that a resin fiber having a core-sheath structure is used as the resin binder. . As the core-sheath fiber to be used, one having a melting point of the sheath lower than that of the core is used, and the thermocompression molding temperature is lower than the melting point of the core of the core-sheath fiber and capable of melting the sheath.

That is, a mixture of plant fibers and core-sheath fibers is mixed to form a mat, and the mixture is pressed at a temperature lower than the melting point of the core of the core-sheath fibers and capable of melting the sheath to form a fiber board. It can be molded.

Here, FIG. 1 shows a plant fiber 1 and a core-sheath fiber 2.
It shows a schematic explanatory view of a fiber board obtained by thermocompressing a mixture of a mixture of a mixture of a plant fiber 1 and a core-sheath fiber 2, entangled with each other, an intersection of the plant fiber 1 and the core-sheath fiber 2, and a core. At the intersection of the sheath fibers 2, there is always an adhesive portion 3 in which the sheath portion of the core-sheath fiber 2 is melted and becomes a binder to be adhesively cured, and the intersection point where the adhesive portion 3 exists is It exists in the entire area and has a structure in which the dimensions do not change as a whole. In addition, since the amount of resin on the surface of the formed fiber board decreases, the fiber board is used as a base material (surface decorative sheet (natural veneer, resin sheet, etc.), reinforcing material (plywood, MD).
When it is bonded to (F etc.)), the adhesive enters the inside to improve the adhesiveness.

On the other hand, FIG. 2 shows a schematic explanatory view of a fiber board in which a thermoplastic resin fiber 4 is conventionally used as a binder. If the thermoplastic resin fibers 4 are not sufficiently melted, the proportion of the melted portions 5 existing at the intersections with the plant fibers 1 is reduced, and the binding force of the plant fibers 1 is weak, and a dimensional change occurs. Further, if the amount of the fibers of the thermoplastic resin is increased and the thermoplastic fibers are sufficiently melted in order to secure the dimensional stability, the amount of the resin on the surface increases and the adhesiveness to the base material deteriorates.

By the way, the fiber board obtained by thermocompressing the mixture of the plant fiber and the core-sheath fiber may be used as it is as a fiber-based building board, but a mixture of the plant fiber and the core-sheath fiber may be used. A base material (surface decorative sheet (natural veneer, resin sheet, etc.), reinforcing material (plywood, MDF, etc.)) may be laminated and integrated on a fiber board obtained by thermocompression molding to form a fiber building board. Further, in constructing a fiber-based building board by laminating and integrating a base material on a fiber-based board obtained by thermocompressing a mixture of plant fiber and core-sheath fiber, the plant fiber and the core-sheath fiber were mixed. After forming the fibrous board by thermocompressing the mixture, a base material may be adhered to the fibrous board with an adhesive, or a mixture of plant fiber and core-sheath fiber is thermocompressed. At this time, the fiber-based building board may be formed by laminating and integrating the fiber-based board obtained by molding the mixture by superimposing the mixture on the substrate and thermoforming.

Here, if the melting point of the sheath is too high, the press temperature for hot pressing the mixture and the base material such as the natural veneer is the same as the press temperature of the base material (110 ° C. to 160 ° C.).
Since it cannot be pressed with, the base material such as natural veneer is likely to crack or warp, which is not preferable. Further, if the melting point of the sheath is too low, there is a problem that the dimensional change at high temperature becomes large. Therefore, in the present invention, the melting point of the sheath is 110
C. to 150.degree. C. This makes it possible to prevent the base material from cracking, warping, or the like when heat-pressing the mixture and a base material such as a natural veneer to form a wood-based building board, and has excellent dimensional stability. It can form building boards. Also, after forming the fiber board,
Even when the base material is adhered with an adhesive, a part of the resin is melted under the adhesive press conditions, the wettability with the adhesive is improved, and the adhesive strength is improved.

The plant fiber may be wood fiber or non-wood fiber. Examples of non-wood fibers include kenaf, straw, and palm.

The resin constituting the core-sheath fiber is not particularly limited as long as it is a thermoplastic resin, but polyester resin, polypropylene resin, polyethylene resin, nylon resin and the like are preferably used.

The adhesive is not particularly limited as long as it can be cured and adhered by a hot press, but acrylic emulsion resin, phenol resin,
Melamine resin, aqueous vinyl urethane resin and the like can be preferably used.

Further, in addition to the plant fiber and the resin binder, a thermosetting resin may be further mixed to form a mixture. In this case, the thermosetting resin is in a weight ratio of 5 to 50%, preferably 20.
Blend at ~ 40%. As described above, when a thermosetting resin is further mixed in addition to the plant fiber and the resin binder to form a mixture, the thermosetting resin after molding reduces the springback of the fiber-based building board made of the fiber-based board, and the fiber. The surface hardness of the board can be improved.

As the thermosetting resin, a resin that is well compatible with plant fibers is used.
Melamine resin, urethane resin and the like can be preferably used.

By the way, when the mixture is subjected to thermocompression molding, it is laminated and integrated with the base material so that handling of the fiber board after molding is eliminated, and plywood is used as the base material to simultaneously perform composite integration. In this case, it is possible to cover defects such as dents and cracks in the plywood.

[0029]

Examples (Example 1) As the plant fibers, dried kenaf fibers (fibers cut to a fiber length of 50 mm and defibrated) were used. The above-mentioned kenaf fiber, a phenol resin (Register Top PG4853 manufactured by Gunei Chemical Co., Ltd.), and a core-sheath fiber cut to a length of 50 mm (Melty 3380 manufactured by Unitika Ltd .; melting point of core: 200 ° C., sheath And a melting point of 160 ° C.) at a ratio of 50 parts by weight, 30 parts by weight, and 20 parts by weight at a temperature of 180 ° C. and a pressure of 10 kg / cm.
^2. Thermocompression molding was performed so that the specific gravity became 0.7 after a pressing time of 5 minutes to obtain a fiber board having a thickness of about 3 mm. At 180 ° C., an aqueous urethane resin was used on one side of the obtained fiber board.
Press for 1 minute and slice oak veneer (0.3mm
(Thickness) was adhered to manufacture a fiber-based building board. (Example 2) Kenaf fiber (having a fiber length of 50
The dried product was used after being cut into mm and disentangled. The above kenaf fiber, a phenol resin (Register Top PG4853 manufactured by Gunei Chemical Co., Ltd.), and a length of 50 m
m / m fiber cut into m (Melty 3380 manufactured by Unitika Ltd .; melting point of core is 200 ° C., melting point of sheath is 160)
C) and 50 parts by weight, 30 parts by weight, and 20 parts by weight, respectively, and thermocompressed so that the specific gravity becomes 0.7 at a temperature of 180 ° C., a pressure of 10 kg / cm ² , and a pressing time of 5 minutes. Then about 3
A mm thick fiber board was obtained. Using an aqueous urethane resin, the resulting fiber board was pressed at 180 ° C. for 1 minute to adhere a 9 mm-thick plywood, and then similarly adhered an oak sliced veneer (0.3 mm-thick). A fiber-based building board was manufactured. (Example 3) Kenaf fiber (fiber length 50
The dried product was used after being cut into mm and disentangled. The above kenaf fiber, a phenol resin (Register Top PG4853 manufactured by Gunei Chemical Co., Ltd.), and a length of 50 m
m / m fiber cut into m (Melty 3380 manufactured by Unitika Ltd .; melting point of core is 200 ° C., melting point of sheath is 160)
50 ° C.), 30 parts by weight, and 20 parts by weight, respectively, are placed on a 9 mm thick lauan plywood, and the temperature is 180 ° C., the pressure is 10 kg / cm ² , and the clamping time is 5
The fiber-based building board having a thickness of about 13 mm was manufactured by hot-press molding in minutes.

The fibrous building boards obtained in Examples 1, 2 and 3 were examined for adhesiveness, dimensional stability and warpage after pressing.

Adhesion is determined by plane tensile strength, boiling test,
A caster test was conducted. The dimensional stability was measured by measuring the dimensional change of the thickness from the beginning when absorbing water for 24 hours at normal temperature.

The results show that the fiber-based building boards obtained in any of the examples have a plane tensile strength of 10 kg / cm ² or more, and peeling does not occur even in the boiling test. No peeling occurred even in the caster test, and the adhesion was excellent. Also, the dimensional change in thickness is 1
It was 0% or less, and the dimensional stability was good.

[0033]

As described above, the invention according to claim 1 of the present invention is a method for producing a fiber-based building board by thermocompressing a mixture of a vegetable fiber and a resin binder. The resin binder is a resin fiber having a core-sheath structure, the melting point of the sheath of the core-sheath fiber is lower than the melting point of the core, the thermocompression molding temperature is lower than the melting point of the core of the core-sheath fiber, and the temperature at which the sheath can be melted Therefore, by heating and pressing near the melting point of the sheath, the sheath of the core-sheath fiber is melted in the entire region and the fibers can be bonded to each other in the portion where the plant fiber and the core-sheath fiber and the core-sheath fiber intersect with each other. As a whole, the dimensions are unlikely to change, and the amount of resin on the surface is reduced, so that the adhesiveness when adhering to the base material is also improved.

Further, in the invention described in claim 2, in addition to the effect of the invention described in claim 1, the melting point of the sheath is 11
Since the temperature is from 0 ° C to 150 ° C, when adhering to the substrate,
It is possible to prevent the base material from cracking or warping, and to have excellent dimensional stability.

Further, in the invention of claim 3, in addition to the effects of the invention of claim 1 or claim 2, a thermosetting resin is further compounded in addition to the plant fiber and the resin binder. Since it is a mixture, the thermosetting resin can reduce the spring back of the fiber-based building board made of the fiber-based board and improve the surface hardness of the fiber board.

In addition, in the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, when the mixture is hot-pressed, it is superposed on a substrate. Since the base material and the base material are laminated and integrated, the fiber base board and the base material, which are formed simultaneously with the molding of the fiber base board by thermocompression molding of the fiber mat, can be laminated and integrated at the same time.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a fiber board obtained by thermocompressing a mixture of plant fibers and core-sheath fibers according to the present invention.

FIG. 2 is a schematic explanatory view of a fiber board in which fibers of a thermoplastic resin are used as a conventional binder.

[Explanation of symbols] 1 plant fiber 2 core-sheath fiber

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Claims (4)

[Claims] 1. A method for producing a fiber-based building board by thermocompression molding a mixture of a vegetable fiber and a resin binder, wherein the resin binder is a resin fiber having a core-sheath structure. A method for producing a fiber-based building board, wherein the melting point of the sheath is lower than that of the core, and the thermocompression molding temperature is lower than the melting point of the core of the core-sheath fiber and the sheath can be melted. 2. The method for producing a fiber-based building board according to claim 1, wherein the melting point of the sheath is 110 ° C. to 150 ° C. 3. The method for producing a fiber-based building board according to claim 1, wherein a thermosetting resin is further blended in addition to the plant fiber and the resin binder to obtain a mixture. 4. The method for producing a fiber-based building board according to claim 1, wherein when the mixture is hot-pressed, it is laminated on the base material and integrated with the base material. .