JPH08245929A - Adhering method of wood - Google Patents

Abstract

PURPOSE: To provide an adhering method giving high moisture content with preventing shrinkage according to drying and generation of elongation, warpage and cracking in adhering of thin wood plates or decorating material, etc., by inserting a specific hot-melt type moisture-absorption curing adhesive sheet between materials to adhered wherein one side is wood and heat-pressing. CONSTITUTION: A hot-melt type moisture-absorption curing adhesive sheet containing a polymer having carboxyl group in a molecule and a metal oxide (e.g. oxide of strontium or barium) is inserted between materials to be adhered wherein at least one side is wood and the wood is adhered by heat-pressing at 50-200 deg.C, preferably 80-160 deg.C under 1-30kg/cm<2> , preferably 5-10kg/cm<2> pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adhering adherends, at least one of which is wood. In particular, the present invention relates to a method for adhering wood which has a high water content and is excellent in adhering thin wood boards, decorative materials and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for adhering wood such as wood boards and decorative materials, there has been known a method for adhering a liquid adhesive such as urea / melamine-based or vinyl acetate-based. It was being done. However, according to such a method, the adhesive, the moisture contained in the wood and the temperature after adhesion,
There has been a problem that the adherend expands and contracts or warps significantly due to climate change such as humidity. In addition, in the pressing process of the laminated board, 20
There was a problem that took ~ 30 minutes. Furthermore, the use of organic solvents requires time for the curing process, and environmental hygiene measures and disaster prevention measures were also required. On the other hand, in order to suppress the warp and expansion of the wood, a method of pressure-bonding a flexible pressure-sensitive adhesive or a moisture-curing pressure-sensitive adhesive at room temperature was also considered, but especially for wood with a high water content. In this case, the treatment method by cold pressing cannot prevent shrinkage due to drying, for example, and causes a problem of cracking. Further, unlike the above liquid adhesive, such an adhesive which is pressure-bonded at room temperature has a problem that the surface condition is not smooth because the adhesive does not deposit on the surface of the adherend.

According to the present invention, the surface state of the adherend after adhesion is smooth between the adherends of which at least one is wood, especially wood, especially a high water content, thin wood board, decorative material, etc. Another object of the present invention is to provide a wood bonding method that can bond wood without causing expansion, contraction, warpage, or cracking.

[0004]

The present inventors have completed the present invention as a result of intensive studies to achieve the above object.

That is, according to the present invention, a hot-melt type moisture-absorption hardening adhesive sheet containing a polymer having a carboxyl group in the molecule and a metal oxide is provided between adherends, at least one of which is wood, and heated. The present invention relates to a method for adhering wood, which is characterized by crimping. Further, in the above method, heating and pressure bonding is performed at a temperature of 50 to 200 ° C. and a pressure of 1 to 30 kg.
/ Cm ² It relates to a method for adhering wood, characterized in that it is performed at.

[0006]

According to the method for adhering wood according to the present invention, when adhering wood, particularly high wood content, thin wood boards, decorative materials, etc. It hardens in time and quickly develops a strong adhesive force, so it does not shrink with drying and does not warp or crack. Further, since the hot-melt pressure-sensitive adhesive is melted and deposited on the surface of the adherend due to the thermocompression bonding, the surface condition of the adherend after adhesion can be made smooth. Further, it is possible to shorten the curing time and avoid disaster prevention measures due to the involvement of organic solvents.

The hot-melt type moisture-absorption curing adhesive used in the present invention comprises a polymer having a carboxyl group in the molecule,
It contains a metal oxide.

As the polymer having a carboxyl group in the molecule, a polymer having the following carboxyl group-containing monomer as an essential component and optionally copolymerized with other copolymerizable monomer can be preferably used. Examples of the carboxyl group-containing monomer include unsaturated carboxylic acid compounds such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and crotonic acid.

Other copolymerizable monomers include
There is an alkyl ester of acrylic acid or methacrylic acid, and specifically, methyl acrylate, whose alkyl group has about 1 to 12 carbon atoms, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, Butyl methacrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate and the like can be mentioned. Further, vinyl acetate, styrene and the like can be copolymerized.

The polymer having a carboxyl group in the molecule preferably has a carboxyl group in the polymer molecule in an amount of 0.5 to 40 in order to maintain the balance between the adhesive force and the cohesive force.
% By weight, more preferably 5 to 20% by weight. If the carboxyl group in the polymer molecule is less than 0.5% by weight, the crosslinking with the metal oxide is difficult to proceed and thus it is difficult to cure, and the adhesive property tends to be deteriorated. Tend to occur.

As the metal oxide which is the other component of the hot melt type moisture-curing adhesive used in the present invention, an oxide of a metal of Group IIa of the Periodic Table can be preferably used, and for example, calcium, strontium and barium can be used. An oxide of the selected metal may be used. This metal oxide does not cure in the dry state at room temperature or under heating, but exhibits its function as a cross-linking agent only when it absorbs moisture, and the curing is accelerated by further heating.

The above metal oxides may be used alone or in any two of them.
It may be a mixture of one or more kinds, or an admixture containing a simple substance, for example, an admixture such as alumina cement containing calcium oxide, Portland cement, or natural cement.

The metal oxide is preferably 10 to 200 parts by weight, more preferably 3 parts by weight, based on 100 parts by weight of the polymer.
Mix 0-100 parts by weight. If the compounding amount of the metal oxide is less than 10 parts by weight based on 100 parts by weight of the polymer,
Since curing is not carried out, shrinkage due to drying of wood cannot be prevented, and cracks tend to occur. If it is more than 200 parts by weight, the adhesion to wood tends to decrease.

If necessary, known additives such as a cross-linking agent, a tackifier, an antiaging agent, a plasticizer, a stabilizer, a pigment and a filler can be added to the hot-melt type moisture-curing adhesive. .

The hot-melt type moisture-absorption-curing pressure-sensitive adhesive sheet used in the present invention comprises a single layer of the above-mentioned hot-melt type moisture-absorption-curing pressure-sensitive adhesive or the hot-melt type moisture-absorption curing pressure-sensitive adhesive layer on both sides of the substrate. The substrate is not particularly limited, and examples thereof include foam, plastic film, nonwoven fabric, paper and the like.

The hot-melt type moisture-absorption-curing pressure-sensitive adhesive sheet may be produced by a method known per se. For example, the hot-melt type moisture-absorption-curing pressure-sensitive adhesive is dissolved in an organic solvent, and this is melted with a roll coater, reverse coater, bar coater, After coating with a fountain coater or the like, the organic solvent is dried and removed.

The thickness of the hot-melt type moisture-absorption-curing pressure-sensitive adhesive sheet is appropriately selected depending on the purpose, but is usually 30 to 500.
μm is preferable, and 50 to 150 μm is more preferable.

The wood of the present invention can be adhered by providing the hot-melt type moisture-absorption-curing pressure-sensitive adhesive sheet between adherends and heating and pressing it with a heat press to cure it.

The pressing temperature is preferably 50 to 200 ° C.,
80-160 degreeC is more preferable. If less than 50 ° C,
Since curing is not promoted, shrinkage due to drying of wood cannot be completely prevented and cracking tends to occur. Above 200 ° C., the warp of wood tends to increase due to a rapid decrease in water content of wood.

The pressing pressure is preferably ^{1~30kg / cm 2, 5~10kg / cm} 2 is more preferable. 1 kg /
If it is less than cm ^2, since adhesion is poor, tend to not be prevented shrinkage due to drying of the wood, 30kg / cm ²
If it is larger, the hot-melt type moisture-absorption curing adhesive tends to squeeze out.

The pressing time is not particularly limited and is usually longer than the curing time of the pressure-sensitive adhesive used. Therefore, the pressing time is appropriately selected according to the pressing temperature, the pressure and the pressure-sensitive adhesive to be used, and is usually about 30 seconds to 300 seconds, and in some cases, even shorter curing is possible.

Regarding the present invention, as one adherend,
Although it is wood, the wood includes oak, beech, cedar,
A preferable example is a natural wood veneer such as cypress. The thickness of the veneer is usually preferably 0.1 to 1.0 mm, more preferably 0.2 to 0.3 mm. The water content of the veneer is preferably 20 to 90%, more preferably 40 to 60%. If the water content is less than 20%, the veneer tends to crack, and if it is more than 90%, the shrinkage rate of the wood due to drying increases, so the veneer cracks and the warp after bonding increases. Tend. The wood is preferably plate-shaped, and its thickness is usually preferably 0.1 to 5.0 mm, more preferably 0.2 to 1.0 mm.

The other side of the adherend is not particularly limited, but in addition to the above wood, a laminated material such as Lauan material or plywood is preferably exemplified. For example, the thickness of the laminated wood or the plywood is preferably 1 to 100 mm, more preferably 2 to 20 mm. Also, for example, the water content of laminated wood or plywood is 10
-40% is preferable and 20-30% is more preferable. If the water content is less than 10%, cracking tends to occur, and if it exceeds 40%, the shrinkage rate of the wood due to drying increases, so that the warpage after adhesion tends to increase.

[0024]

EXAMPLES Examples will be given below to explain the present invention in detail, but the present invention is not limited to these examples.

Example 1 100 parts by weight of butyl acrylate, 7 parts by weight of acrylic acid, 230 parts by weight of ethyl acetate and 0.3 part by weight of benzoyl peroxide were charged into a three-necked flask, and dissolved oxygen was removed in a nitrogen stream for 1 hour. After that, the temperature is raised to about 70 ° C for 10
The time was maintained to obtain a copolymer solution. 50 parts by weight (calcium oxide: about 67% by weight) of Portland cement (400 mesh pass: trade name Portland Cement, manufactured by Onoda Cement Co., Ltd.) previously dehydrated and dried was added to 100 parts by weight of the copolymer solution. Contained), dispersed in ethyl acetate, added, and applied by a roll coater so that the thickness after drying would be 80 μm to obtain a hot-melt type moisture-absorption cured adhesive sheet. This hot-melt type moisture-absorption hardening adhesive sheet is attached to a laminated material (Lauan material) having a thickness of 5 mm,
A single plate (beechwood) having a thickness of 0.2 mm and a water content of 50% was placed thereon, and was heat-pressed at 100 ° C. × 10.
It was thermocompression bonded under the condition of kg / cm ² × 1 minute.

Example 2 Adhesion was performed in the same manner as in Example 1 except that the pressing temperature was changed to 120 ° C.

Example 3 Adhesion was performed in the same manner as in Example 1 except that the pressing temperature was changed to 150 ° C.

Example 4 40 parts by weight of butyl acrylate, 50 parts by weight of methyl methacrylate, 10 parts by weight of acrylic acid, 300 parts of ethyl acetate
Parts by weight and 0.3 parts by weight of benzoyl peroxide were placed in a three-necked flask and dissolved oxygen was removed in a nitrogen stream for 1 hour, and then the temperature was maintained at about 70 ° C. for 15 hours to obtain a copolymer solution. For this copolymer solution, 40 parts by weight of dehydrated and dried Portland cement (400 mesh pass: trade name Portland cement, manufactured by Onoda Cement Co., Ltd.) was added to 100 parts by weight of the copolymer solution (calcium oxide:
(Containing about 67% by weight), dispersed in ethyl acetate and added,
It was applied by a roll coater so that the thickness after drying would be 80 μm to obtain a hot-melt type moisture-absorption-curing pressure-sensitive adhesive sheet. This hot-melt type moisture-absorption hardening adhesive sheet is laminated on a laminated material (Lauan material) having a thickness of 5 mm, and a thickness of 0.2 m is applied thereon.
m, a single plate (beech wood) with a water content of 50% was placed
It was thermocompression bonded under the conditions of 100 ° C. × 10 kg / cm ² × 1 minute by a heat press.

Comparative Example 1 Adhesion was performed in the same manner as in Example 1 except that the pressing temperature was changed to 23 ° C.

Comparative Example 2 A urea / melamine adhesive was applied to a laminated material (lauan material) having a thickness of 5.0 mm, and a veneer (beech material) having a thickness of 0.2 mm and a water content of 50% was applied on the laminated material. Place, 120 ℃ × 10k
It was pressure-bonded under the condition of g / cm ² × 1 minute.

Comparative Example 3 Double-sided adhesive tape (trade name No. 500, manufactured by Nitto Denko)
Affixed to a laminated wood (Lauan) with a thickness of 5.0 mm, and a veneer with a thickness of 0.2 mm and a water content of 50% on it.
Was placed and pressure-bonded under the conditions of 120 ° C. × 10 kg / cm ² × 1 minute.

[Evaluation Test] Cracks of the laminates obtained in Examples and Comparative Examples (visual observation of cracks in veneer), surface condition (observation by touch), warpage (one day after pressure bonding, flat surface) The state of the measurement of the height of floating when placed is shown in Table 1. Further, under the pressure-sensitive adhesive and pressure-bonding conditions used in Examples and Comparative Examples, a veneer plate having a water content of 50% was bonded, and a tensile shear adhesive strength (bonding area 15 mm × 15 mm, measured after 30 minutes of pressure bonding, tensile speed 10 mm / min. , Measuring atmosphere 20 ℃
× 65% RH) was also measured and is shown in Table 1.

[0033]

[Table 1]

[0034]

EFFECTS OF THE INVENTION According to the present invention, when a wood, especially a wooden board or a decorative material having a high water content, is adhered, it is cured in a short time by thermocompression bonding using a hot-melt type moisture-absorption curing adhesive sheet. However, since a strong adhesive force is quickly developed,
It does not shrink due to drying, and can prevent expansion and contraction, warpage, and cracking. Further, the pressure-sensitive adhesive is melted by heating and pressure bonding and deposited on the surface of the adherend, so that the surface condition of the adherend after adhesion can be made smooth. Furthermore, in adhering building members, the working time can be greatly shortened, and the need for disaster prevention measures due to the involvement of organic solvents can be avoided.

Claims (2)

[Claims] 1. A hot-melt moisture-absorption-curing pressure-sensitive adhesive sheet containing a polymer having a carboxyl group in the molecule and a metal oxide is provided between adherends, at least one of which is wood, and thermocompression bonding is performed. A method for adhering wood, characterized by. 2. A temperature of 50 to 200 ° C. and a pressure of 1 to 30 kg.
The method for adhering wood according to claim 1, wherein the method is carried out by thermocompression bonding at a pressure of / cm ² .