JPH10128711A - Wooden panel and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wooden panel with good nailing properties, improved nail holding force and reduced warpage and twisting caused by change in humidity and its method for preparation. SOLUTION: This wooden panel 1 is prepd. by a method wherein wooden fiber and/or wooden powder prepd. of acetylated wooden fiber and/or the wooden powder obtd. by grinding the acetylated wooden fiber whose size is selected and is made uniform are coated with an isocyanate compd. as a binder and furthermore, these wooden fiber and/or wooden powder are coated with a polyether polyol as a softening binder and these are integrally molded into a body. The method for preparing this wooden panel comprises coating the wooden fiber and/or wooden powder prepd. of acetylated wooden fiber and/or the wooden powder obtd. by grinding the acetylated wooden fiber whose size is selected and is then made uniform with the isocyanate compd. and the polyether polyol simultaneously or successively and molding them under heat and pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wood panel suitably used for a gauge board of a pachinko machine or the like and a method for producing the same, and is obtained by pulverizing wood fiber, acetylated wood fiber, or both wood fibers. By selecting the size of the wood powder, then applying a binder to the wood powder of the same size and molding and integrating, the nailing performance is good and the nail holding force can be improved, and This is to reduce warpage and twist caused by a change in humidity.

[0002]

2. Description of the Related Art In general, wood panels are widely used for various purposes, and one of the uses is a gauge plate of a pachinko machine. Plywood is used as a wood panel for this type of application. Plywood is obtained by stacking and bonding a plurality of beech veneers so that the fiber direction of each veneer is orthogonal to each other, or only the surface layer. A beech veneer is used, and the core layer is a veneer of another tree type. However, the plywood has a veneer line in the veneer, knots, cracks, etc.
It is difficult to strike nails straight, the nail holding force is small, and this plywood is easily warped or twisted due to humidity change, and has poor dimensional stability, so it is convenient to use as a gauge plate for pachinko machines. There were also bad points. In recent years, the shortage of timber resources and the protection of forests have become a problem, and it is clear that deforestation will become increasingly difficult in the future. Is expected to become unstable or supply shortage, and prices will rise. In view of this, the use of a wood panel obtained by effectively using thin wood pieces and wood fibers of wood pieces that have been conventionally discarded has been studied.

[0003] The wood panel includes a wood fiber integrated board (fiber board) made of wood fiber, a wood piece assembly board (particle board) made of wood pieces, and a wood thin board (OSB) made of wood piece (strand). Etc. are known. However, in the wood fiber integrated board, the rock layer is formed by densifying the surface layer by hot pressing after the forming step, while the core layer is formed coarsely, so that it is used as a gauge board of a pachinko machine. There was a drawback that nails could not be hit because the surface layer was very hard. Also,
If the density was reduced to a low density until the nail could be hit, the required nail holding force could not be obtained. Further, in the above-mentioned wood small piece laminated board or wood thin laminated board, elements (components) such as wood thin pieces are large, hardness varies depending on the element, and a gap between elements is large, and foreign matter enters the gap. As a result, a uniform panel could not be obtained, and even if the nail was hit straight, the nails turned in different directions one by one, resulting in poor nailing properties.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a good nailing property, can improve a nail holding force, and has a warp or twist caused by a change in humidity. And a method of manufacturing the same.

[0005]

According to the first aspect of the present invention, the size of acetylated wood fiber and / or wood powder obtained by pulverizing the acetylated wood fiber is selected, and this size is determined. A wood panel characterized in that a binder is applied to the aligned wood fibers and / or wood powders and molded and integrated, is a means for solving the above-mentioned problem. The invention according to claim 2 is characterized in that the wood fibers and / or wood powders having the same size have a mesh size of 150 μm or more.
The wood panel according to claim 1, characterized in that the wood panel has passed through a 500 µm sieve. Further, the invention according to claim 3 is characterized in that the coating amount of the binder is 7% in solid content with respect to 100 parts by weight of acetylated wood fiber and / or wood powder obtained by pulverizing the acetylated wood fiber. The wood panel according to claim 1 or 2, wherein the weight of the wood panel is from 30 to 30 parts by weight. According to a fourth aspect of the present invention, there is provided a wood panel according to the first, second or third aspect, wherein the binder is an isocyanate compound and a polyether polyol. The invention according to claim 5 is characterized in that the acetylated wood fiber and / or 100 parts by weight of the wood powder obtained by pulverizing the acetylated wood fiber has an isocyanate compound coating amount of 4 parts by solids. The wood panel according to claim 4, wherein the amount of the polyether polyol is 3 to 12 parts by weight. Further, the invention of claim 6 selects the size of the acetylated wood fiber and / or the wood powder obtained by pulverizing the acetylated wood fiber, and then adjusts the size of the wood fiber and / or the size of the wood powder. Another object of the present invention is to provide a method for producing a wood panel, comprising a step of applying a polyether polyol simultaneously with or after the application of an isocyanate compound to a wood powder and hot pressing.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in order to make the present invention easier to understand, embodiments of a wood panel of the present invention and a method of manufacturing the same will be described. Such an embodiment shows one aspect of the present invention, does not limit the present invention, and can be arbitrarily changed within the scope of the present invention. FIG. 1 is a cross-sectional view showing an example of an embodiment of a wood panel of the present invention.
In the figure, reference numeral 1 denotes a wood panel. Such a wood panel 1 can be manufactured, for example, as follows. First, wood fibers are prepared. As the wood fiber used here, wood obtained by chipping wood with a chipper and defibrating the obtained chip is used. For fibrillation, 150
A method of evaporating with high-pressure steam of about ° C and then fibrillating with a disc refiner or the like is used. The size of the wood fiber is about 0.1 to 1.0 mm in thickness and about 0.2 to 50 mm in length. As the wood fibers, those having a small thickness are preferable because the acetylation reaction proceeds well.

Next, the wood fiber thus obtained is acetylated in a gas phase or a liquid phase, and the acetylation is preferably performed in a gas phase in terms of cost. Prior to acetylation, the wood fiber is dried and the water content is 3% or less,
Preferably, it is preferably set to 1% or less. If the water content is too high, acetic anhydride of the acetylating agent vapor reacts with the water first and consumes acetic anhydride, so that the amount of the acetylating agent used increases or the supply of acetic anhydride becomes insufficient. And the degree of acetylation tends to decrease.

As a specific method of acetylation in the gas phase, for example, a reaction vessel is filled with a mixture of acetic anhydride and xylene as a source of an acetylating agent at the bottom thereof, and a stainless steel wire or the like is formed above the mixture. There is a method of putting wood fiber on this net, heating the acetic anhydride and xylene to generate acetic anhydride and xylene vapor, and bringing acetic anhydride and xylene vapor into contact with the wood fiber. . The reaction time is about 15 minutes to 3 hours, but can be appropriately changed depending on the required degree of acetylation. The reaction temperature is about 120 to 160 ° C., and the reaction pressure is about 2 atm to normal pressure.

When diluting acetic anhydride with xylene which is an inert solvent which does not react with the acetylation, the amount of xylene used is 7 times the total amount with acetic anhydride.
0% by weight or less. By using such a mixture of acetic anhydride and xylene, when acetic anhydride and xylene are mixed and vaporized, the boiling point of acetic anhydride (BP.
Xylene having a boiling point close to that of 39.5 ° C.) (B.
P. 138-144 ° C.) helps stabilize the reaction temperature. That is, by maintaining the temperature of the acetylating agent in a certain temperature range, the reaction temperature during the acetyl reaction can be kept in a certain temperature range of about 120-160 ° C., especially Since it is easy to maintain at about 140 ° C., the acetyl reaction, which is an exothermic reaction, can proceed in a mild state, and the reaction operation becomes easy,
Excessive acetylation and thermal degradation of wood fibers can be suppressed.

In the present invention, the wood fiber can be pretreated with a catalyst prior to the acetylation in the gas phase. In this pretreatment, the wood fibers obtained by defibration are treated with 1 to 10 acetates such as sodium acetate and potassium acetate.
% Aqueous solution for about 10 minutes to 2 hours, or a method of injecting the aqueous solution into wood fibers under reduced pressure. The wood fibers that have been subjected to this pretreatment are:
After drying, it undergoes the acetylation reaction described above. By performing the pretreatment with the catalyst, the acetylation reaction in the next step is promoted, the reaction can be completed in a short time, and a product having a high acetylation degree can be obtained. However, since the acetylation reaction is an exothermic reaction, if this exotherm accumulates, the wood fiber may become too hot and carbonize, so to make the reaction mild and avoid sudden heat generation It is effective not to use a catalyst. The use of a catalyst is suitable for shortening the acetylation time and improving the degree of acetylation.However, when a catalyst is used, the catalyst component tends to remain in the wood fibers after treatment. When bonding or painting a panel using fibers, there is a possibility that the adhesive strength, paint adhesion strength and the like may be adversely affected, which is not preferred. The degree of acetylation of the wood fiber by the above acetylation is usually 8 to 2 in terms of weight increase rate.
The content is about 5%, preferably about 15 to 25%, but can be appropriately changed according to the required moisture resistance. Next, the wood fiber subjected to the acetylation reaction is washed with water or hot water to remove the attached acetylating agent, and then dried to a predetermined water content.

Next, the acetylated wood fiber is crushed using a crusher to obtain wood powder, and then the size of the wood powder is selected. A sieve is preferably used for the size selection here, and the woody powder that has passed through the sieve is used in a subsequent step. The sieve opening is 150 μm to 5
Those having a thickness of about 00 μm, preferably about 150 μm to 425 μm are used. If the mesh size of the sieve is less than 150 μm, the rigidity and nail holding force are reduced.
If it exceeds 500 μm, the woody powder passing through the sieve is too large, and the thickness direction of the plate material becomes inhomogeneous as in the case of a particle board or a laminated wood slab, making it difficult to strike a nail straight.

Next, the wood powder whose size has been adjusted by sieving is put into a coating machine and a binder is applied. The application method is not particularly limited, but it is preferable to apply by a spray method. For example, when the wood powder is put into a rotating drum (blender) rotating at a low speed and the wood powder falls naturally in the drum, A method of spraying a binder or the like is preferably used. As a binder applied here, an adhesive such as a melamine resin, a phenol resin, a urea resin, an epoxy resin, or a polyurethane resin is used. It is desirable to use a soft adhesive as the adhesive. The amount of binder applied is wood powder 1
The solid content is about 7 to 30 parts by weight, preferably about 15 to 25 parts by weight, based on 00 parts by weight. If the coating amount of the binder is less than 7 parts by weight, the moisture resistance is reduced, and the wood panel is likely to be warped or twisted due to moisture absorption. Further, even if the binder is applied in an amount exceeding 30 parts by weight, no increase in moisture resistance can be expected any more, the density increases, and it is economically disadvantageous. As the binder, it is particularly preferable to use an isocyanate compound such as crude polymethylene diphenyl diisocyanate (crude PMDI) and a polyether polyol. This isocyanate compound has strong adhesiveness as a binder. The ratio (weight ratio) of the isocyanate compound to the polyether polyol is preferably 9: 6. This polyether polyol has the effect of softening the binder. It is desirable to use a polyether polyol having a molecular weight of 200 to 2,000. If the molecular weight of the polyether polyol is 200 or less, the binder after hot pressing becomes too hard, and if the molecular weight is 2000 or more, the binder after hot pressing becomes too soft.

The method of applying the polyether polyol is not particularly limited, but a spray method is preferable. For example, an isocyanate compound which is a polyurethane resin-based adhesive is applied in a rotary drum (blender) used at the time of applying the binder. A method of spray-coating a polyether polyol while stirring the woody powder is preferably used. The coating amount of the polyether polyol is 3 to 12 parts by weight, preferably 6 to 10 parts by weight, based on 100 parts by weight of acetylated wood fiber and / or wood powder obtained by pulverizing the acetylated wood fiber. If it is a part, the hardness of the wood panel after hot pressing can be made suitable for use as a gauge board for game tables such as pachinko machines. The amount of the isocyanate compound applied is 4 parts by solid based on 100 parts by weight of acetylated wood fiber and / or wood powder obtained by pulverizing the acetylated wood fiber.
The content is preferably from 18 to 18 parts by weight, and the content of the polyether polyol is preferably from 3 to 12 parts by weight. When the coating amount of the polyether polyol is less than 3 parts by weight,
The binder after hot pressing is hard, the nail may be bent due to the hardness of the binder even if the nail is hit straight on the wooden panel, and the length of the wooden panel is about 5 mm to 7 mm using an air driver. When hitting flat plate screws (for fixing brackets), the rotation may not be smooth and the screw head may stop. On the other hand, if the applied amount exceeds 12 parts by weight, it is too soft, and the holding power of the nail is lost.

Next, after removing the solvent of the binder of the wood powder coated with the isocyanate compound and the polyether polyol by drying, the wood powder is formed using a forming machine to produce a mat. As a method of drying the woody powder, for example, a method of drying the woody powder while transporting it in a pipe with hot air, or the like is preferably used. As the forming method, it is preferable to use dry forming in which wood powder is sprayed on a hot plate. For this forming, a conventionally used method and apparatus can be used as they are.

The wood panel 1 is obtained by applying an isocyanate compound to a acetylated wood powder having a uniform size, further applying a polyether polyol, and molding and integrating the same, and has a specific gravity of about 0.06 to 0.1. 08. Uniform density in the thickness direction, uniform hardness as a whole, and a narrow space between wood powders as elements, so there are no foreign substances other than isocyanate compounds and polyether polyols, and water absorption after immersion in 25 ° C water for 24 hours. Thickness expansion rate (JIS A 590
5-1994 (5.10.)) Excellent dimensional stability of about 0.5 to 2%. The specific gravity of the wood panel 1 is preferably about 0.65 to 0.75. The woody panel 1 thus obtained is subjected to finishing such as sanding on the surface as necessary, and is made into a product.

In the wooden panel 1 of this embodiment,
Since acetylated wood fiber is used, it has excellent moisture resistance, so it can reduce warpage and twist due to humidity change, has good dimensional stability, and is hardly affected by humidity Therefore, the nail holding force is stable. In addition, the size of the wood powder obtained by pulverizing the acetylated wood fiber is selected, and the wood powder having the uniform size is used. , And the size is uniform, there is no foreign matter other than the binder between the wood powders, and the density in the thickness direction is uniform, and there is no bedrock layer like the conventional wood fiber laminated board, so when nailing Since the nail can be driven straight and the nailing property is good, it is possible to use an automatic nailing machine that continuously drives the nail. Further, since the density in the thickness direction is uniform and the density of the core layer is not low unlike the conventional wood fiber laminated board, a high nail holding force can be obtained. Furthermore, in this wood panel 1, when applying a binder, a binder having a hardness suitable for a gauge board of a game table such as a pachinko machine can be selected, and a panel having a more uniform hardness can be obtained. The hardness of the nail does not hinder the driving of nails and flat plate screws, and the nailing performance is excellent. Therefore, such a wood panel 1 can be suitably used as a gauge board of a pachinko machine or the like.

In the above-described embodiment, the wood powder obtained by pulverizing the acetylated wood fiber is sieved, and a wood panel is manufactured using the wood powder of which the size is uniform by the sieving. When the size of the acetylated wood fiber is small, the size is selected by sieving or the like as it is without grinding, and a wood panel is manufactured using the wood fiber of the same size. You may do so.

In the above embodiment, a wood panel is produced by applying an isocyanate compound to a wood powder obtained by pulverizing acetylated wood fibers, then applying a polyether polyol, and hot pressing. Although the example has been described, the isocyanate compound is applied to the acetylated wood fiber and / or the wood powder obtained by pulverizing the acetylated wood fiber, and at the same time, the polyether polyol is applied.

[0019]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only these Examples. (Example) The thickness is about 0.1 to 1.0 mm and the length is 0.1 mm.
Wood fibers (trade name: F4-17, manufactured by Canfor Corporation) of about 2 to 50 mm were acetylated using a gas phase acetylation treatment apparatus manufactured by Sumitomo Chemical Engineering. As the acetylating agent used here, acetic anhydride was used. The degree of acetylation of the wood fibers was 20% in terms of weight increase. Then, the acetylated wood fiber was ground using a power mill (trade name, manufactured by Dalton) to obtain wood powder. After this,
The size of the woody powder was selected using a sieve having openings of 425 μm.

Next, the wood powder that had passed through the sieve was put into a rotating drum rotating at a low speed, and a binder was spray-coated when the wood powder dropped naturally in the drum. As the binder, crude polymethylene diphenyl diisocyanate (trade name: Sumidur 44V20, manufactured by Sumitomo Bayer Urethane Co., Ltd.) was added in an amount of 1 to 100 parts by weight of the wood powder.
2 parts by weight (solid content) were used after dissolving in acetone. Thereafter, a polyether polyol (polyol 0705, trade name) was added as a binder to the wood powder in the drum.
8 parts by weight of wood powder (100 parts by weight of Sumitomo Bayer Urethane Co., Ltd.) was dissolved in acetone and applied. Then, after drying and removing the solvent of the binder of the wood powder to which the binder was applied, the wood powder was formed using a homing machine to a thickness of 500 mm.
I got a mat.

Then, the mat was pre-pressed to a thickness of 200 mm, and then hot-pressed using a press to obtain a wood panel having a thickness of 20 mm. The heat pressure conditions here are as follows: a hot plate temperature of 150 ° C., and a press pressure of 5.6.
MPa and the pressing time were 20 minutes. Further, the surface of the wooden panel was sanded as a finish to obtain a molded product having a length of 500 mm, a width of 500 mm and a thickness of 18.5 mm.

Examination of the dimensional stability of this molded product revealed that it was superior in dimensional stability to changes in humidity as compared with the plywood of Comparative Example 1 described later. Further, a nail was punched into the molded article of the example, and the holding ratio of the nail holding force after being left for one week in an atmosphere temperature of 35 ° C. and a relative humidity of 95% was examined. The holding ratio was 98%. It was found that the nail holding force was superior to that of the plywood of Comparative Example 2 and the molded article of Comparative Example 2 (wood fiber laminated board). Further, when the nailing property of the molded article of the example was examined, the nailing property was also good.

(Comparative Example 1) Length 500 mm, width 500 m
m, 13 beech veneers having a thickness of 1.5 mm were laminated and bonded so that their fiber directions were orthogonal to each other to obtain a 19.0 mm thick beech plywood. When the dimensional stability and nail holding force of this beech plywood were examined by the same method as in the example, the amount of warpage was 7 mm at the maximum and the holding ratio of the nail holding force was about 95%.

(Comparative Example 2) A wood fiber having a thickness of about 0.1 to 1.0 mm and a length of about 0.2 to 50 mm was put in a rotary drum similar to that used in the examples, and The binder was spray-applied when the wood fibers dropped naturally. As the binder, a polyurethane-based adhesive containing crude polymethylene diphenyl diisocyanate was used in an amount of 20 parts by weight on a solid basis with respect to 100 parts by weight of the wood fiber.
Next, the solvent of the binder of the wood fiber to which the binder was applied was dried and removed, and the wood fiber was formed using a homing machine to obtain a mat having a thickness of 500 mm. Then, pre-press this mat to reduce the thickness to 2
After the thickness was reduced to 00 mm, it was further hot-pressed using a press machine to obtain a wood fiber laminated board having a thickness of 20 mm. The heat and pressure conditions here are as follows: hot plate temperature 150 ° C., press pressure 5.
The pressure was 6 MPa and the pressing time was 20 minutes. Further, the surface of the wood fiber laminated board was sanded as a finish to obtain a molded product having a length of 500 mm, a width of 500 mm, and a thickness of 18.5 mm. The nail holding force of the molded product of Comparative Example 2 (wood fiber laminated board) was examined by the same method as in the example, and the retention ratio of the nail holding force was about 54%, which was lower than that of the molded product of the example. It turned out that the nail holding power was bad.

[0025]

As described above, in the wood panel according to the first aspect, since the acetylated wood fiber is used, the wood panel has excellent moisture resistance. And torsion can be reduced, the dimensional stability is good, and the nail holding force is stable because it is hardly affected by humidity. Further, the size of the wood powder and / or the acetylated wood fiber obtained by pulverizing the acetylated wood fiber is selected, and the wood powder and / or wood powder having the same size is used. Since the size of the elements constituting the wood panel can be made uniform, the density in the thickness direction is uniform, and since there is no bedrock layer as in the conventional wood fiber laminated board, the nailing property is good, Use of an automatic nailing machine is possible. Further, since the density in the thickness direction is uniform, a high nail holding force can be obtained because the density of the core layer is not low unlike the conventional wood fiber laminated board.

In the wood panel according to the second aspect of the present invention, in particular, the wood fiber and / or the wood powder having a uniform size have passed through a sieve having an opening of 150 μm to 500 μm. And / or the size of the wood powder is not excessively large and is appropriate, and since the size of the elements is made small, foreign matter other than the binder does not enter between the elements, and the thickness direction of the panel becomes more uniform. In the wood panel according to claim 3,
In particular, since the applied amount of the binder is set to 7 to 30 parts by weight in solid content with respect to 100 parts by weight of the wood fiber and / or wood powder, the moisture resistance is good, and the warpage and twisting caused by the humidity change are prevented. Can be reduced. In the wood panel according to the fourth aspect, in particular, the binder is softened by applying a polyether polyol as a softening binder to the wood fiber and / or wood powder coated with the isocyanate compound. It is possible to select a binder with a suitable hardness for gauge boards of game tables such as pachinko, etc., and it becomes a wood panel with little variation in hardness, and the hardness of the binder makes it possible to drive nails and flat plate screws. Without disturbing,
Nailability is improved.

In the wood panel according to the fifth aspect, in particular, an isocyanate compound and a polyether polyol are used as a binder, and the amount of the binder applied is 100 parts by weight of the wood fiber and / or wood powder. By being 7 to 30 parts by weight in solid content,
The moisture resistance is good, the adhesiveness of the binder is tough, and the releasability after molding is good. Further, the coating amount of the isocyanate compound in the binder is 4 to 4 in solid content.
18 parts by weight and the coating amount of polyether polyol is 3 to
By setting the content to 12 parts by weight, a panel having a hardness suitable for a gauge plate of a pachinko machine and a more uniform hardness after hot pressing is formed, and the nailing property is excellent. Therefore, the wood panel of the present invention has good nailing properties, has a high nail holding force, and can reduce warpage and twist caused by a change in humidity. Therefore, a gauge board of a pachinko machine, a playground equipment board, and a building material And the like. In the method for manufacturing a wood panel according to the sixth aspect, the above-described configuration enables the wood panel to be suitably used for manufacturing the wood panel of the present invention.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an embodiment of a wood panel of the present invention.

[Explanation of symbols]

 1 ... wood panel.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Kaneo Kimoto 10-1 Nakazawa-cho, Hamamatsu-shi, Shizuoka Yamaha Corporation

Claims (6)

[Claims] 1. The size of acetylated wood fiber and / or wood powder obtained by pulverizing the acetylated wood fiber is selected, and the wood fiber and / or wood powder having the same size is selected. A wood panel, wherein a binder is applied and molded and integrated. 2. The wood panel according to claim 1, wherein the wood fibers and / or wood powders having the same size have passed through a sieve having an opening of 150 μm to 500 μm. 3. The coating amount of the binder is 7 to 30 parts by weight in solid content with respect to 100 parts by weight of acetylated wood fiber and / or wood powder obtained by pulverizing the acetylated wood fiber. 2. The method according to claim 1, wherein
Or a wood panel according to 2. 4. The wood panel according to claim 1, wherein the binder is an isocyanate compound and a polyether polyol. 5. An application amount of the isocyanate compound in a solid content of 4 to 18 parts by weight based on 100 parts by weight of the acetylated wood fiber and / or wood powder obtained by pulverizing the acetylated wood fiber. The wood panel according to claim 4, wherein the coating amount of the polyether polyol is 3 to 12 parts by weight. 6. The acetylated wood fiber and / or the size of the wood powder obtained by pulverizing the acetylated wood fiber is selected, and then the wood fiber and / or wood powder having the same size is selected. A method for producing a wood panel, comprising a step of applying a polyether polyol at the same time as or after applying the isocyanate compound and performing hot-press molding.