JP2663055B2 - Wood fiberboard for molding and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention mainly relates to wood fibers,
The present invention relates to a primary molded wood fiber board for molding and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, various methods have been known as methods for producing a fiber mat for molding and a fiber board using wood fibers as a main raw material. For example, a mixture obtained by adding and mixing a long fiber, a thermosetting resin adhesive, or a thermosetting resin adhesive to a wood fiber obtained by defibrating and drying a chip, followed by forming and compression drying. Alternatively, a method is known in which a soft fiber plate is molded, then defibrated into fibrillated fibers, mixed with a long fiber and a resin, deposited, and entangled with a needle punch to form a mat. Have been.

However, the above method requires compression drying at a temperature below the curing temperature of the thermosetting resin adhesive mixed with the wood fiber, and it is difficult to adjust the compression drying conditions, and it is difficult to adhere to the wood fiber. When adding the agent, it is added by spraying, so the loss occurs due to the scattering of the adhesive by spraying, it is difficult to add uniformly, and since the adhesive impregnates the wood fiber, an excessive amount of addition is necessary The method requires an extra process of producing a soft fiber board and a wool, and requires an excessive amount of resin to be added to the defibrated wood fiber as well. Had the problem of.

[0004]

In view of such circumstances, the present inventors have conducted intensive studies to provide a wood fiber board for molding which is easy to handle and excellent in moldability. It was completed. That is, the present invention has created the following means. That is,

[0005] In a wood fiber board for molding in which wood fibers are bonded with a thermoplastic resin, a powder obtained by coating wood fibers and a high temperature thermoplastic resin around a low temperature thermoplastic resin different from the melting temperature of the high temperature thermoplastic resin. , Granules, chips, flakes or fibrous materials are mixed, and without heating the high-temperature thermoplastic resin, by hot pressing at the melting temperature of the low-temperature thermoplastic resin, the wood fibers are mixed with the low-temperature thermoplastic resin. Wood fiberboard for molding formed in a three-dimensional network structure, and

A powdery, granular, chip-like or flake material obtained by coating wood fiber obtained by defibrating wood around a high-temperature thermoplastic resin and coating it with a low-temperature thermoplastic resin different from the melting temperature of the high-temperature thermoplastic resin. Shape or fibrous material,
After forming wood fiber into wood fiber mat,
A method for producing a wood fiber board for molding, comprising hot-press molding at the melting temperature of a low-temperature thermoplastic resin without melting the high-temperature thermoplastic resin, and bonding the wood fibers to a three-dimensional network structure with the low-temperature thermoplastic resin.

[0007]

According to the above construction, the wood fiber board for molding of the present invention is firstly molded at a temperature not lower than the melting temperature of the low-temperature thermoplastic resin, and at the time of secondary molding, it is desired to have a desired temperature above the melting temperature of the high-temperature thermoplastic resin. Can be molded into a shape.

[0008]

[Structure] The wood fiber board for molding of the present invention is obtained by cutting, as wood fibers, hardwood such as Rawan, Kapole, chestnut and poplar, and softwood such as pine, cedar, etc. into chips, followed by defibration according to a conventional method. Wood fibers obtained by the above method can be used.

The thermoplastic resin to be added to these wood fibers includes polyethylene, polypropylene, polystyrene, polyvinyl chloride, nylon, polyethylene terephthalate, polyacrylic acid, polyacrylonitrile and the like. In the present invention, two types of thermoplastic resins, a high-temperature thermoplastic resin having a high melting temperature and a low-temperature thermoplastic resin having a melting temperature lower than the high-temperature thermoplastic resin, are selected and used in combination. These thermoplastic resins are added to the wood fibers in the form of powder, granules, chips, flakes or fibers. By adding in such a form, it can be uniformly mixed with the wood fiber,
In addition, the loss of resin can be reduced without impregnation into the wood fiber. In particular, in the present invention, the periphery of a powdery, granular, chip-like, flake-like or fibrous high-temperature thermoplastic resin is added and mixed in a form coated with a low-temperature thermoplastic resin, respectively. Since it is added in a coated form, the high-temperature thermoplastic resin and the low-temperature thermoplastic resin can be uniformly mixed with each other. The amount of the thermoplastic resin added is 10 to 30% by weight with respect to the wood fiber.

The structure of the wood fiber board for molding according to the present invention is constituted as one wood fiber layer or as a composite board having at least one metal foil layer disposed inside the wood fiber layer in the thickness direction. The metal foil used at this time may be a metal such as iron, aluminum, stainless steel, or copper having a thickness in the range of 20 to 100 μm and subjected to rust prevention treatment such as plating if necessary. Also, as a metal foil layer,
A metal foil provided with fine holes or a metal woven fabric woven using a metal thread can be used. By arranging the metal foil layer in this manner, the bending strength of the molded wood fiber board can be improved, and cracks may be generated during handling when heating and pressing to a desired shape by secondary molding. Not
It is possible to manufacture a wood fiber board for molding of a larger size. In addition, by using a metal foil having partial air permeability due to micropores or the like, the metal foil regulates the movement of water remaining in the wood fiber to escape to the outside during heating and pressing. Can be prevented from puncturing.

In order to produce a wood fiber board for molding in accordance with the present invention, wood fibers are obtained by steaming chips of softwood or hardwood to degreasing and softening, and then defibrating by a defibrating device. This wood fiber has a length of 1-3
Most of them have a diameter of about 0 mm and a diameter of about 2 to 300 µm, and have a shape like a bundle of conduits and temporary conduits or cells, and the cell wall around the fiber is torn or cracked It absorbs a lot of moisture and moisture because of its high content. The obtained wood fiber is dried by a drying device. A powdery, granular, chip-like, flake-like or fibrous material in which a low-temperature thermoplastic resin is coated around a high-temperature thermoplastic resin in a blender is added to the dried wood fiber in a blender. Next, the wood fibers are put into a hot air duct and dried while blowing. The blowing speed at this time is about 15 to 20 m /
Although it is seconds, it can be adjusted over a wide range depending on the specific gravity of the wood fiber, the feed amount, the processing capacity of the preceding and following processes, and the like. The wood fibers are dried to a water content of 6 to 15% by the blowing by the hot air.

The blown wood fibers are conveyed to a forming device and dropped on a conveyor, where a mixture of wood fibers and a thermoplastic resin is deposited, and then temporarily pressed to form a wood fiber mat. After cutting the fiber mat into appropriate dimensions, the wood fiber board for molding can be obtained by heating and pressing at a temperature higher than the melting temperature of the low-temperature thermoplastic resin and not melting the high-temperature thermoplastic resin.

When a metal foil layer is provided, a wood fiber mat obtained by temporary pressing is laminated on the front and back surfaces of the metal foil, and then pressed by a similar method. When laminating the wood fiber mat and the metal foil, the adhesive strength of the wood fiber board for molding is further increased by using the same adhesive as the high-temperature thermoplastic resin added to the wood fiber on the front and back surfaces of the metal foil. Can be improved.

[0014]

The wood fiber board for molding of the present invention is selected from a combination of a high-temperature thermoplastic resin and a low-temperature thermoplastic resin and used in combination. Thereby, a wooden board for molding can be obtained. Even if a part of the high-temperature thermoplastic resin is melted by the heating at this time, it is still a thermoplastic resin. Then, the wood fiber board for molding of the present invention is heated and pressed by a mold and then subjected to secondary molding into a desired shape. In this case, the temperature of the primary molding can be easily controlled without any adverse effect. Furthermore, since the thermoplastic resin is added to the wood fibers in the form of powder, granules, chips, flakes or fibrous materials, they can be uniformly mixed. In particular, in the present invention, the dispersion and mixing of each thermoplastic resin are also uniformly performed by adding in the form of powdery granules, chips, flakes or fibers in which the periphery of the high-temperature thermoplastic resin is coated with the low-temperature thermoplastic resin. be able to. Further, since the loss of the added resin is smaller than that of the conventional spray method, the excess amount of the added resin can be reduced.

[0015]

The present invention will be described in more detail with reference to the following examples.

Example 1 First, an example of manufacturing a wood fiber mat will be described.
That is, the radiator pine chips were heated at 160 ° C and 7K.
The mixture was boiled at g / cm ² for 5 minutes to perform degreasing and softening treatment. The chips were defibrated by a defibrator type refiner, and the obtained wood fibers were dried. The wood fiber is put into a blender, and in the blender, a thermoplastic resin coated with a polyethylene resin around a polypropylene resin is mixed with a 10% polyethylene resin (melting temperature; 130 ° C.) based on the amount of the wood fiber, 18% After being added and mixed at a ratio of a polypropylene resin (melting temperature: 180 ° C.), it was conveyed to a forming device. The conveyed wood fibers were dropped and deposited on a screen conveyor. The wood fiber was temporarily pressed, cut into an appropriate length, inserted into a hot press, and hot-pressed at 140 ° C. to obtain a wood fiber board for molding.

Example 2 The wood fiber mat obtained in Example 1 by pre-pressing and 45 μm
A thick iron foil is sequentially laminated from the top in the order of wood fiber mat / iron foil / wood fiber mat, then inserted into a hot press and hot-pressed at 150 ° C. for 5 minutes to a thickness of 13 mm and a specific gravity of 0.1 mm.
7 was obtained.

Claims (2)

(57) [Claims] 1. A wood fiber board for molding in which wood fibers are bonded with a thermoplastic resin, wherein the wood fibers and the high temperature thermoplastic resin are coated with a low temperature thermoplastic resin different from the melting temperature of the high temperature thermoplastic resin. Powdered, granular, chip-like, flake-like or fibrous materials are mixed and hot-pressed at the melting temperature of the low-temperature thermoplastic resin without melting the high-temperature thermoplastic resin. A wood fiber board for molding characterized by being bonded to a three-dimensional network structure with a resin. 2. A powdery form in which wood fibers obtained by defibrating wood are coated around a high-temperature thermoplastic resin with a low-temperature thermoplastic resin different from the melting temperature of the high-temperature thermoplastic resin.
After mixing granules, chips, flakes or fibrous materials, forming wood fibers into a wood fiber mat, then hot-press molding at the melting temperature of the low-temperature thermoplastic resin without melting the high-temperature thermoplastic resin And a method of manufacturing a wood fiber board for molding, wherein the wood fibers are bonded to each other in a three-dimensional network structure with a low-temperature thermoplastic resin.