JPH09267440A - Production of wooden veneer overlaid decorative panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bond wooden veneer to a medium density wooden fiberboard by an energy-saving type bonding method using no solvent or water, to facilitate the penetration into the medium density wooden fiberboard and to especially enable the use of raw veneer not generating a crack or the like. SOLUTION: This wooden veneer overlaid decorative panel is constituted by bonding wooden veneer 4 to the surface of a substrate 1 of which the surface part is composed of a medium wooden fiberboard. In this case, as an adhesive, a compsn. containing polymethylene poly (phenylisocyanate) and at least either one of polypropylene glycol or polypropylene glycol diglycidyl ether as essential components is used.

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 wood veneer-coated veneer having a high water resistance using a medium-density wood fiber board in an energy-saving or resource-saving manner.

[0002]

2. Description of the Related Art A prepolymer of diisocyanate and polyethylene glycol, polypropylene glycol or its copolymerized glycol has been used for a long time as an adhesive for adhering wood veneer (particularly, raw veneer or raw wood containing water). There is. However, since this adhesive has a high viscosity, if it is used as it is to bond a single plate to a medium-density wooden fiber board, there is no anchoring effect on the medium-density wooden fiber board, and there is a drawback that the surface layer of the medium-density wooden fiber board is torn and peeled off. .

In order to prevent this, the prepolymer can be infiltrated into the medium-density wood fiberboard as a solvent solution in advance, but in this case, the solvent must be evaporated and energy and resources are lost, which is environmentally friendly. Is not preferable either. In addition, MDI (= diphenylmethane-4,4 '
-A sol or emulsion type adhesive in which (diisocyanate) is dispersed in water is also known, but in this case energy is required to evaporate the water, and the anchoring effect on the medium density wood fiber board is not always sufficient. . In addition, P-MDI (=
Polymethylene polyphenyl polyisocyanate) is impregnated into the surface layer of the medium density wood fiber board to strengthen the medium density wood fiber board, but in this case as well, it takes time to penetrate, and especially epoxy compound When used in combination with, a solvent is also used for penetration.

[0004]

The inventors of the present invention have achieved various aspects of the present invention by conducting various experiments in order to improve the above-mentioned state of the art, and the adhesion of a wood veneer to a medium-density wood fiber board is improved. , Is an energy-saving type / environmental-improvement type that does not use solvents or water that need to be evaporated and removed.
And it is easy to penetrate into medium-density wood fiber board and has excellent anchoring effect, and in particular, it is a technical problem to develop a method for manufacturing a wood veneer-coated decorative board that can be used as raw veneer.
In that case, dry cracking of the veneer does not occur, so the manufacturing method is a resource-saving type.

[0005]

[Means for Solving the Problems] "Claim 1" states that "a wood veneer (4) is adhered to the surface of a substrate (1) whose whole or surface portion is formed of medium density wood fiber board. A method for producing a wooden veneer-coated decorative board (A) to be formed, wherein the adhesive is polymethylene polyphenyl polyisocyanate and a molecular weight of 2
At least one of polypropylene glycol or polypropylene glycol diglycidyl ether of 00 or more and 1000 or less is an essential component. "," Claim 2 "" Wood veneer (4) It has a thickness of 1 mm or less, including ".

According to this, a molecular weight of 200 or more, 100
Polypropylene glycol or polypropylene glycol diglycidyl ether of 0 or less is polymethylene polyphenyl polyisocyanate (= also known as Polymeric M
It is called DI or P-MDI. Hereinafter referred to as P-MDI. ) Has good compatibility with P-MDI and has the effect of lowering the viscosity of P-MDI, it has good permeability to the medium-density wood fiberboard (1) or (2), and when it reacts and cures, it becomes a medium-density wood fiberboard ( 1) or (2)
F has an excellent anchoring effect, and does not require evaporation of solvent or drying of water as in the conventional example, and if pressure / heat pressing is performed as it is, bonding is completed in several minutes. In addition, this adhesive can also use raw wood veneer (4) containing water, so it is possible to eliminate the drying process in which cracking of the wood veneer (4) occurs, and thus the wood veneer (4) ) Yield improves, which can contribute to resource saving.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. The first embodiment of the wood floor material (A) of the present invention is, as shown in FIG. 1, an example in which the entire substrate (1) is composed of a medium-density wood fiber board. The wooden decorative veneer (4) is attached to the surface of (1) with an adhesive. In the figure, (3) is an adhesive layer formed on the surface of the medium-density fiber substrate (1). Also,
In the second embodiment of the present invention, as shown in FIG. 2, the substrate (1) is
It is composed of a substrate body (1a) and a medium-density wood fiber board (2), and the medium-density wood fiber board (2) is attached to the surface of the substrate body (1a) with an adhesive. And this medium density fiberboard
The wood veneer (A) is formed by bonding the wood veneer (4) to the surface of (2) with an adhesive. Therefore, in any of Examples 1 and 2, the wood veneer (4) is attached to the surface of the medium density wood fiber board (1) or (2) through the adhesive layer (3).

The characteristic part of the present invention is that the dry wood veneer (4) or the raw veneer (4) containing water and having a thickness of 1 mm or less is used as the surface of the medium density wood fiber substrate (1) or the substrate (1). Medium density wood fiberboard
(2) An adhesive used for producing a wood decorative board (A) by adhering to the surface of the (2). The adhesive has a molecular weight of 200 with P-MDI.
Above, and a mixture of polypropylene glycol of 1000 or less, or P-MDI and a mixture of polypropylene glycol diglycidyl ether having a molecular weight of 200 or more and 1000 or less, P-MDI and a molecular weight of 200.
It is a mixture of the above polypropylene glycol having a molecular weight of 1000 or less and the polypropylene glycol diglycidyl ether having a molecular weight of 200 or more and 1000 or less.

P-MDI is represented by the structural formula shown below, and there are various types, but generally n = 0 to 2
And the viscosity is 200-2000 centipoise.

[0010]

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Polypropylene glycol or polypropylene glycol diglycidyl ether having a molecular weight of 200 or more and 1000 or less has a good compatibility with P-MDI,
P-MDI has the effect of lowering the viscosity, the reaction at room temperature is mild, and it is easy to handle. Molecular weight 100
When it is 0 or more, compatibility with polypropylene glycol or polypropylene glycol diglycidyl ether or a mixture thereof becomes poor, and there is no effect of decreasing viscosity, and dipropylene glycol (weight average molecular weight = 135) has no compatibility, and the usable life is Is also short. Therefore, in order to lower the viscosity of P-MDI and improve the penetration into medium density wood fiberboard, the present invention requires polypropylene glycol or polypropylene glycol diglycidyl ether having a viscosity within this specific range or a mixture thereof. .

Polypropylene glycol or polypropylene glycol diglycidyl ether, or a mixture of polypropylene glycol and polypropylene glycol diglycidyl ether, and P-MDI are mixed in such a manner that the hydroxyl groups are equal to or less than the isocyanate groups, and (1/2) equivalents. The above is appropriate.

The water content of the raw veneer (4) is usually up to 30%, but in this situation there is no cracking and the yield of the veneer (4) is good, and the veneer (4) swells sufficiently. It is in a state of being. Of course, it is also possible to use a dried veneer (4). As the substrate body (1a) for bonding the medium density wood fiber board (2),
For example, in addition to wood boards such as particle boards, various boards such as silica boards, wood cement boards, and inorganic boards such as mineral fiber boards having a specific gravity of 0.5 or more can be used.

In the present invention, the adhesive which is the above-mentioned specific isocyanate composition is applied and penetrated on the surface of the medium density wood fiber board (1) or (2), and immediately the raw veneer (4) or the dry veneer (4) is applied. No need to evaporate solvent or water because it is placed and pressed and heat-bonded, and moreover, veneer (4), especially in the case of raw veneer (4), veneer (4) Since it has no crack damage, it is extremely resource-saving and energy-saving, and has a very significant industrial effect. Since the adhesive according to the present invention has excellent permeability, it penetrates to the inside when applied to the surface of the medium density wood fiberboard (1) or (2), and the veneer (4) is placed and added. Since the infiltrated portion is hardened by pressure and heat bonding, it exhibits an excellent anchoring effect and does not tear only the surface layer of the medium density wood fiber board (1) or (2) as in the conventional case.

(Embodiment) Although there are various embodiments of the present invention, most generally, the hydroxyl group should be in an equivalent amount to (1/2) equivalent to the isocyanate group of P-MDI. , P-MDI molecular weight of 200 or more,
At least one of polypropylene glycol or polypropylene glycol diglycidyl ether of 1000 or less is blended and stirred well. This makes P
-The viscosity of MDI is reduced and the permeability to medium density wood fiberboard is increased. At this time, if the reaction is desired to be carried out at room temperature, the pot life of the composition or the composition is 2-3 days when a reaction catalyst such as a tertiary amine is not used. Apply P-MDI to the surface of the plate. The isocyanate composition (= adhesive) penetrates from the coated surface of the medium-density wood fiberboard to the inside within a few minutes.

The raw veneer can be used without drying by slicing wood softened by boiling treatment to a thickness of 0.4 mm or less. That is, while sliced, placed on the surface of a medium density wood fiber board coated with an adhesive, 5-10kgf /
The adhesion is completed by pressing under a pressure of cm ² at 100 to 140 ° C. for several minutes. For dried veneer, after slicing,
Dry, choose one that does not crack and place it on the surface of a medium density fiberboard coated with an adhesive, 5-10 kgf / c as above
Bonding is completed by pressing under a pressure of m ² at 100 to 140 ° C. for several minutes.

The raw veneer is adhered to the medium-density wood fiberboard as it is swollen, but the surface protection by painting after that can be carried out by an ordinary method and used as a building material such as flooring and wall materials. it can.

As the P-MDI used in the examples of the present invention, any commercially available product can be used as long as the isocyanate equivalent is known. Polypropylene glycol is a commercially available product having a molecular weight of 200 to 1000, but may be mixed when used. For example, an average molecular weight of 65 is obtained by mixing equimolar amounts of polyproylene glycol having a molecular weight of 300 and 1000
It is used as 0.

Hereinafter, the present invention will be described more specifically with reference to Examples, but these are not representative of all of the present invention. [Example-1] 20 parts by weight of P-MDI (NC031.4%) was mixed with 15 parts by weight of polypropylene glycol having a molecular weight of 300, and this was used as an adhesive to prepare a urea type medium density wood fiber board having a thickness of about 3 mm. About 90 g / m ² of the adhesive composition according to the present invention was applied. The adhesive penetrated the surface of the medium density wood fiberboard almost simultaneously with the application. Immediately, a cypress grain veneer was placed on the thus-obtained medium-density wood fiber board and pressure-bonded at 120 ° C. and 10 kgf / cm ² for 3 minutes.
The water content of the cypress grain veneer was about 60%, and the swelling rate was about 6%. This swelling rate was maintained even when the single-density medium density wood fiber board was dried at 60 ° C, and the water absorption rate when immersed in water for 5 days at room temperature was about 50%, but swelling in the width direction The ratio is less than 0.5%, and the swelling ratio of thickness is about 7.5.
%, It was excellent in water resistance. In addition, the adhered raw cypress veneer has the original appearance of cypress, no leaching of the adhesive, and peeling of the veneer even after drying the medium density wood fiberboard after the water resistance test at 60 ° C. Without causing cracks,
The original size was restored, and the swelling of the veneer was retained.

[Example-2] P-MDI (NC0 31.4%) 2 was prepared by bonding a urea-type medium-density wood fiber board having a thickness of about 3 mm to the surface of a plywood board having a thickness of 9 mm.
Polypropylene glycol with a molecular weight of 300 in 0 parts by weight
Using a mixture of 5 parts by weight as an adhesive, a Melvo veneer (thickness: 0.2 mm, water content: about 50%, swelling ratio: about 5%),
Bird's eye maple veneer (thickness 0.1 mm, water content about 8
0%, swelling rate about 7%), curled maple veneer (thickness: 0.
1 mm, water content of about 74%, and swelling ratio of about 7.5%), each of which is applied with an adhesive of about 90 g / m ^{2 in} the same manner as in [Example-1], and 120 ° C, 10 kgf / cm. ² , 3-5
Bonding was performed under the pressing condition for 1 minute. All of the veneers are firmly bonded while maintaining the swollen state, and the room temperature is 120
The water absorption rate after water immersion for 50 hours was 50 to 60%, but the swelling rate in the width direction was 0.5% or less, and the swelling rate in the thickness direction was 1%.
When the content was 0% or less, the original shape was restored by drying, and neither peeling nor cracking occurred. In addition, there was no leaching of the adhesive in the appearance, and no troubles such as paint finish were observed.

[0021]

As is apparent from the above description, the present invention has an advantage that it is not necessary to dry the solvent and water, and further, when using a raw veneer which is not dried in advance, cracks or the like are caused. It is resource-saving and energy-saving without any loss. In addition, peeling and chipping due to the weakness of the substrate surface layer, which was a drawback of the wood veneer laminated decorative board using medium density wooden fiber board for the substrate, are also prevented, the performance is remarkably improved in water resistance, Results are extremely effective.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of a wooden decorative board according to the present invention.

FIG. 2 is a sectional view of a second embodiment of the wooden decorative board according to the present invention.

[Explanation of symbols]

 (A)… Wooden decorative board (1)… Substrate (1a)… Substrate body (2)… Medium density wood fiberboard (3)… Adhesive layer (4)… Wooden veneer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Oyama 2-3-3 Nakanoshima, Kita-ku, Osaka City Daiken Kogyo Co., Ltd. (72) Inventor Kei Ito 2-3-18 Nakanoshima, Kita-ku, Osaka Within Daiken Kogyo Co., Ltd.

Claims (2)

[Claims] 1. A method of manufacturing a wood veneer-attached decorative board, which comprises forming a wood veneer on the surface of a substrate which is wholly or entirely formed of a medium-density wood fiber board, and which comprises: A method for producing a wood veneer-coated decorative board, characterized in that the agent comprises at least one of polymethylene polyphenyl polyisocyanate and polypropylene glycol or polypropylene glycol diglycidyl ether having a molecular weight of 200 or more and 1000 or less. . 2. A wood veneer containing water and having a thickness of 1
The method for producing a wood veneer-coated veneer according to claim 1, wherein the veneer has a size of not more than mm.