JP2003311717A - Wood fiberboard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a pulverized waste wood fiber board which has been conventionally discarded as a part of a raw material (recycled raw material) to have a strength equal to or higher than that of a wood fiber board manufactured by a conventional manufacturing method. To obtain a wood fiberboard provided. According to the present invention, it is possible to reduce the consumption of a new raw material, that is, natural wood,
As a result, it can contribute to protection of the natural environment. SOLUTION: A wood fiber obtained by subjecting a raw material obtained by pulverizing or cutting a new piece of wood to a regenerated raw material obtained by pulverizing an existing wood fiber board (for example, MDF) by using an adhesive to form a heat and pressure integrally. Obtain a plate (eg, MDF, PB). The raw material produced is
Apparent density ^{50kg / m 3 ~250kg / m 3} , the fiber length 0
It is desirably a fibrous or chip-shaped one with a diameter of 01 mm to 20 mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wood fiber board obtained by integrally thermocompressing wood fibers and chip pieces with an adhesive.

[0002]

2. Description of the Related Art Particle board (PB), medium density wood fiber board (MDF), high density wood fiber board (HDF), oriented strand board (OSB), wafer boat (W)
As in B), wood pieces are crushed with a refiner or mill to form fibers, or wood pieces are crushed with a crusher to be used as a raw material, which is then thermocompression molded with an adhesive. The wood fiberboard produced in this way is well known. The raw materials are called wood chips, wood fibers, strand pieces, and so on.

In the production of wood fiberboard, for example MDF
In the case of, a piece of wood cut into 25 mm square or smaller is used as a raw material. It has an apparent specific gravity of 20 kg / m ³ ~ with refiners (single disc refiner, double disc refiner, etc.)
The fiber is defibrated into a fibrous form having a fiber length of 50 kg / m ³ and a fiber length of 0.4 mm to 4 mm. Next, an adhesive is applied to the defibrated material, dried, and subjected to steps such as forming and trimming, and then hot-press molding with a hot-press. Some have a single-layer structure and some have a multi-layer structure. In the case of a multi-layer structure, wood material layers are laminated in multiple layers in the forming process. At that time, usually, a middle layer having a relatively large fiber length is provided in the center, and a layer having a short fiber length is provided on the surface layer, that is, the front surface layer and the back surface layer.

The PB is manufactured in substantially the same manner, but a chip-shaped material having a size of about 2 mm to 50 mm is used as a raw material. In the case of PB, it is often the case that a screen is used to sort the raw material pieces, and the raw material pieces are sorted and stacked in multiple layers.
In that case, the surface layer is about 3 mm or less, and the middle layer is 2 mm to 50 mm.
The thing of about mm is normally used. Of course, there is also a PB having a single layer structure.

The wood fiberboard manufactured as described above is used in a wide range of applications such as construction materials, automobiles, furniture and the like. Depending on the purpose of use, in the fibrous or chip-shaped wood raw material, further bacas, grain straw, bamboo,
Hot pressing is also carried out in a state in which plant material is mixed as in the case of the petals.

[0006]

This type of wood fiber board is usually discarded as it is after the end of its purpose of use and is incinerated for fuel. However, now that the protection and effective utilization of wood resources is required from the viewpoint of nature conservation, it is becoming a future task to find a method to reuse wood fiberboard that has been scrapped in some way. .

The present invention has been made from the above point of view, and reuses used wood fiberboard which has been conventionally disposed of by incineration and the like, as a recycled material for a novel wood fiberboard. By doing so, it is intended to reduce the consumption of natural wood and, as a result, contribute to the protection of the natural environment.

[0008]

In order to solve the above-mentioned problems, the present inventor has conducted many experiments and researches and found that the wood fiber board which is a waste material, that is, the existing wood fiber board manufactured by the conventional method. Is mixed into a new raw material obtained by crushing or cutting wood pieces used in the conventional production of wood fiberboard, or layered into a new raw material. In the laminated state,
When it is produced as a wood fiberboard according to the conventional method, the obtained wood fiberboard has a higher strength than wood fiberboard produced only by raw materials obtained by crushing or cutting a new piece of wood. We have found the surprising fact that a wood fiberboard is obtained that is not inferior in terms of performance, but rather has improved strength. This finding completely overturns the fixed concept in the industry that mixing or adding recycled materials from waste materials to new raw materials will adversely affect the wood fiberboard produced, and can be called a person skilled in the art. It was something I could not predict.

The present invention is based on such a discovery,
The wood fiber board according to the present invention is basically formed by integrally thermocompressing a raw material obtained by crushing or cutting a new piece of wood and a regenerated raw material obtained by crushing an existing wood fiber board with an adhesive. It is characterized by In the present invention, the term "crushing" is used to include so-called crushing as well as defibration, that is, a state of being fibrillated. Further, the wood fiberboard according to the present invention may have a single-layer structure,
It may have a multi-layer structure such as a three-layer structure. In the case of a multilayer structure, all layers may be composed of a mixed raw material of a raw material obtained by crushing or cutting a new piece of wood and a regenerated raw material obtained by crushing an existing wood fiber board, at least Any one of the layers may be composed of only the above-mentioned recycled raw material without using the raw material obtained by crushing or cutting a new piece of wood. Other plant materials may be mixed in any of the layers.

In the present invention, the kind of the wood fiberboard obtained is not limited, and a material obtained by defibrating or crushing wood pieces into fiber or chips by an appropriate means is used as a raw material, and an adhesive is applied thereto. All of the conventionally known wood fiberboards obtained by thermocompression molding in the above state are applicable. In the experiment of the present inventor, the manufactured wood fiberboard is MD
The present invention was particularly effective in the case of F and PB.

In the present invention, the wood piece which is the source of the new raw material may be appropriately selected according to the kind of the wood fiberboard to be produced, and is the same as the case of producing by the conventional method. Good. On the other hand, the type of the existing wood fiberboard which is the source of the recycled material is not particularly limited, but MDF is most suitable. The reason is that the pulverized product of MDF has many fibers of a certain size, and the obtained wood fiber board has a uniform surface. Even other types of waste wood fiber boards can be effectively used by adjusting the size and mixing amount of the crushed pieces.

In the present invention, the apparent specific gravity and the fiber length of the recycled raw material obtained by crushing the existing wood fiber board are appropriately selected according to the kind of the wood fiber board to be obtained. In any case, the apparent specific gravity is 50 kg / m ^{3 to} 250 kg /
m ³ and a fiber length of 0.01 mm to 20 mm, or a fibrous shape is preferable. Apparent specific gravity is 50
If it is less than kg / m ³ , uneven coating of the adhesive tends to occur, which is not preferable. Further, if it exceeds 250 kg / m ³ , sufficient bending strength cannot be obtained and a large amount of dust is generated, which is not preferable from the working environment. In addition, if the fiber length is less than 0.01 mm, the amount of adhesive required increases, and a large amount of dust is generated, which is not preferable from the working environment. Also, 20
If it exceeds mm, uneven coating of the adhesive occurs, which is not preferable.

The wood fiberboard according to the present invention is a mixture of a raw material obtained by crushing or cutting a new piece of wood and a regenerated raw material obtained by crushing an existing wood fiberboard. It is different from the wood fiberboard, and the other manufacturing methods are the same as the conventional wood fiberboard manufacturing methods. Usually, both are mixed before the adhesive application step, and the following may be manufactured according to the manufacturing method according to the conventional method. In the case of a multilayer structure, in the case of forming a layer consisting of only the recycled raw material, at least that layer is coated with the adhesive to the recycled raw material without being mixed with the new raw material, and is applied to other layers. The following thermocompression molding process and the like are performed in a state of being directly laminated on top.

There is no particular limitation on the mixing ratio of the new raw material and the recycled raw material obtained by crushing the existing wood fiber board, and in the experiment conducted by the present inventor, the apparent specific gravity and the fiber length are influenced to some extent. However, the bending strength of the obtained wood fiber board tended to be stronger when there were more recycled materials. In particular,
A large improvement in bending strength was observed in the case of forming a layered structure and forming some of the layers (particularly the surface layer) with only the recycled material. The reason for this is understood to be that the entanglement effect between the fibers is effective because it is fibrous and is sufficient in quantity as compared with a normal surface layer material such as PB.

[0015]

EXAMPLES The present invention will be described below with reference to examples. Obviously, the present invention is not limited to this. [Example 1] A mixing device having a mixing function was additionally arranged before the refiner in the conventional MDF production line.
On the other hand, a waste material MDF crushing device equipped with a primary crusher, a quantitative feeder, a secondary crusher, a storage hopper, etc. was installed near the MDF production line. Wood pieces crushed to 25 mm square or smaller were used as a new raw material to be put into a conventional MDF production line. The primary crusher of the waste material MDF crusher is a hammer mill.
It was crushed so as to be less than the corner. The crushed product was sent to a secondary crusher by a quantitative feeder, and further defibrated until it became fibrous to obtain a recycled material. MDF as a secondary crusher
The same refiner as in the production line was used. The apparent specific gravity of the obtained recycled raw material is 50 kg / m ^{3 to} 25.
The fiber length was 0 kg / m ³ , and the fiber length was in the range of 0.01 mm to 20 mm. The regenerated raw material thus obtained is put into a mixing device arranged in front of the refiner in the MDF production line, mixed with the new raw material, and then fed into the refiner in the same manner as the conventional one.
I got F.

A storage hopper was attached after the secondary crusher to store the regenerated raw material in the storage hopper, and then the MDF was used.
In accordance with the progress of the production line, the regenerated raw material was also charged into the mixing device from the storage hopper. In addition, conventional M
A mixing device was additionally arranged after the refiner in the DF production line, and the regenerated raw material was introduced into the mixing device directly from the secondary pulverizer or via the storage hopper. In any case, the same MDF as that produced by the conventional method could be produced.

[Embodiment 2] In front of a screen arranged after a wood piece cutting device in a conventional PB production line,
A mixing device having a mixing function was additionally arranged. On the other hand, the PB
A waste material MDF crusher equipped with a primary crusher, a quantitative feeder, a secondary crusher, a storage hopper, and the like was installed near the production line. Wood pieces crushed to 25 mm square or smaller were used as a new raw material to be put into the PB production line. Waste material MD
The primary crusher of the F crusher was a hammer mill, and the waste material MDF was put therein and crushed to a size of 70 mm square or less. Send the crushed material to the secondary crusher with a quantitative feeder,
Therefore, the fibers are defibrated until the fiber length becomes 0.01 mm to 10 mm, or in a small piece state (length 0.01 mm to 10 mm).
The raw material was obtained by crushing into small pieces each having a thickness in mm and a thickness larger than that of the fiber. A conventional refiner was used as the secondary crusher. The apparent specific gravity of the obtained recycled raw material is 50 kg /
It was m ³ ~250kg / m ^3. The regenerated raw material thus obtained is put into a mixing device arranged in front of the screen in the PB production line, mixed with a new raw material, and then fed into the screen in the same manner as in the conventional case, and thereafter, through the same production process as the conventional PB, PB was obtained.

A storage hopper was attached after the secondary crusher to temporarily store the regenerated raw material in the storage hopper, and then the regenerated raw material was put into the mixing device from the storage hopper in accordance with the progress of the PB production line. In addition, a mixing device is additionally arranged after the screen in the PB manufacturing line,
There, the regenerated raw material was also charged into the mixing device directly from the secondary crusher or via the storage hopper.
In any case, PB similar to that produced by the conventional method could be produced.

[Embodiment 3] Three wood fiberboards according to the present invention are used.
It was manufactured as a layered PB. The central layer was prepared by a conventional method (that is, without using a regenerated raw material), and the surface layers (front surface layer and back surface layer) were prepared by a mixture of the above new raw material and a regenerated raw material, and only a regenerated raw material. As a comparative example, a product in which the surface layer was prepared only with a new material was also manufactured (the proportion of recycled material in the surface layer was 0 w%, which corresponds to the current PB). The steps after forming the layered structure were performed in the same manner as in the case of manufacturing a conventional PB. The pressing was performed at 160 ° C. for 3 minutes.

The center layer has an apparent specific gravity of 100 kg / m ³
A formaldehyde-based adhesive and MDI were applied at 7w% using only new chip pieces of ˜200 kg / m ³ .
The surface layer has an apparent specific gravity of 150 kg / m ^{3 to} 250 kg / m ^3.
No.1 chip pieces and a regenerated raw material that is an existing MDF pulverized product and has an apparent specific gravity of 50 kg / m ^{3 to} 150 kg / m ³ (average apparent specific gravity of 70 kg / m ³ ) and a fiber length of 0.01 mm to 20 mm. Then, the same formaldehyde adhesive and MDI applied at 12 w% were used. The weight ratio of the recycled material in the surface layer is 25 w% and 50
w%. In addition, the same w% adhesive is applied to the recycled raw material only (that is, 100% by weight).
Was also used. Bending strength was measured about them. The results are shown in Table 1.

[0021]

[Table 1]

[Example 4] As a recycled material, an apparent specific gravity of 100 kg / m ^{3 to} 250 kg / m ³ (average apparent specific gravity of 1
Example 3 with the exception of using 50 kg / m ³ ).
Example products and comparative example products were manufactured in the same manner as above, and bending strength was measured in the same manner. The results are shown in Table 2.

[0023]

[Table 2]

[Discussion] As shown in Tables 1 and 2, the PB according to the present invention is a PB without a recycled raw material (that is, produced by a conventional method) while using a pulverized product of waste MDF as a recycled raw material. The bending strength of the PB) is almost equal to or higher than that of the PB), and further, 150% or more, indicating that the use of the waste material has no influence on the manufactured PB.

[0025]

EFFECTS OF THE INVENTION According to the present invention, even if a pulverized product of used wood fiberboard which has been conventionally disposed of is used as a raw material (recycled raw material), the strength is equal to or higher than that of the wood fiberboard produced by the conventional manufacturing method. The wood fiberboard provided is obtained. Therefore, by utilizing the wood fiberboard according to the present invention,
It becomes possible to reduce the consumption of new raw materials, that is, natural wood, and as a result, it is possible to contribute to the protection of the natural environment.

Continued front page    F term (reference) 2B260 AA20 BA02 BA05 BA18 BA19                       CB01

Claims (4)

[Claims] 1. A wood material, wherein a raw material obtained by crushing or cutting a new piece of wood and a raw material obtained by crushing an existing wood fiber board are integrally thermocompression-molded with an adhesive. Fiberboard. 2. The wood fiberboard has a multi-layer structure, and at least one of the layers is a raw material obtained by crushing an existing wood fiberboard without using a raw material obtained by crushing or cutting a new piece of wood. The wood fiber board according to claim 1, wherein the wood fiber board is composed of only one. 3. A raw material obtained by crushing an existing wood fiber board is a fibrous or chip-like material having an apparent specific gravity of 50 kg / m ^{3 to} 250 kg / m ³ and a fiber length of 001 mm to 20 mm. The wood fiber board according to claim 1 or 2. 4. An existing wood fiberboard is a medium density fiberboard (MD
F), and the wood fiberboard to be thermocompressed is a medium density fiberboard (MDF) or particle board (PB).