JPS6131483A - Bonding of wood - Google Patents

Abstract

PURPOSE:To increase the speed of bonding operation, and to improve the bonding strength and water-resistance, by applying an isocyanate compound as a primer to the surface of a wood piece, and using a hot-melt polyester resin adhesive as the adhesive. CONSTITUTION:A primer composed of an isocyanate compound is applied to the bonding surface of a wood piece at a rate of preferably 20-70g/m<2>, and dried spontaneously or with hot air. MOlten polyester resin adhesive is applied to at least one bonding surface of the adherends at a rate of preferably 100-150g/m<2>, and both adherends are pressed together.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for adhering wood in which at least one of the adherends is wood, in which an isocyanate compound is applied as a primer to the adhering surface of the wood, and an adhesive is applied. By using a hot melt type polyester resin adhesive as the adhesive, it is possible to speed up the adhesive work, increase adhesive strength, improve water resistance, etc.

[Conventional technology]

Conventionally, Coria resin adhesive and resorcinol resin adhesive are often used for bonding wood. These adhesives are 1
When curing at 00'C or above, adhesion is completed in a relatively short time, but it still requires 1 to 2 minutes of curing.
This has become a bottleneck in increasing productivity. For this reason,
Adoption of hot to melt adhesive methods is being considered as an adhesive method that allows for extremely short bonding times. This hot nuru 1~
The bonding method takes only a few seconds to cure and can be used with a roll pressure bonding method, which can be expected to greatly improve productivity. The Botmelt adhesive used in hot-melt adhesion using wood as an adherend is E.
VA (ethylene vinyl acetate copolymer) resin adhesives, polyamide resin adhesives, and the like are used.

[Problem that the invention seeks to solve]

However, when adhering wood using these hot null 1-type adhesives, there were drawbacks such as insufficient adhesive strength and extremely poor water resistance.

For example, if a piece of wood glued with hot null 1 to 1 with EVA resin adhesive is soaked in water for a few hours, the adhesive strength will be 1.
It will drastically decrease from /10 to 1/30.

This is because the fiber-H silk weave on the surface of the wood to which it is attached swells with water and swells, and the anchor of the adhesive that has penetrated into the fiber structure and solidified is easily pulled out, resulting in adhesive failure. It is considered to be done.

[Means to solve the problem]

Therefore, in this invention, a prine made of an isocyanate compound is applied to the surface of the wood to be adhered in advance, and the adhesive is bonded with Hora 1-melt type polyester resin adhesive to increase the adhesive strength and greatly improve the water resistance. I tried to improve it.

As the primer in this invention, an isocyanate compound having an active isocyanate group in the molecule is used. For example, a solution may be used in which a prepolymer consisting of a polyisocyanate obtained by adding a diisocyanate to a polyhydric alcohol and a polyol such as a polyester or polyether is dissolved in a solvent such as methylene chloride.

Further, as the polyester resin adhesive, one mainly composed of a thermoplastic polyester resin such as a polyester copolymer made of dimeburu terephthalate and 1,4-butanediol is used. The forms of this adhesive are film, silk, and stick.

It can take any shape such as a bowl, powder, or pellet.

Wood, which is one of the covering materials, is not limited in any way by tree species or shape, and plywood such as lauan plywood is also used. It is desirable that the moisture content of the wood be adjusted in advance to about 6 to 12%, but it is acceptable even if the moisture content is higher than in the conventional case.

The other adherend material is wood or plastic.

Metal etc. are used. For plastics and metals, it is preferable to perform pretreatment such as degreasing treatment by a conventional method. Combinations of adherend materials include, for example, plywood laminated to thin wood sheets such as decorative decks, synthetic resin sheets such as coarse polyvinyl chloride resin sheets, paper impregnated with sialitlate resin, and waves impregnated with noenol resin. 1~
In this invention, a material in which a material such as plywood or the like is bonded together is suitable.

Next, the bonding operation will be explained.

First, a primer made of an isocyanate compound is applied to the surface of the wood to be covered with stone. As the coating method, well-known methods such as brush coating, spray coating, and roll coater coating are used as appropriate depending on the shape of the adherend. The amount of application is 10
-200g/Td1, preferably about 20-7011/m. If the wood is highly absorbent, increase the viscosity of the primer so that there is a sufficient amount of primer on the surface layer.

After application, air dry or hot air dry to allow the reaction between the isocyanate compound and the wood to proceed sufficiently. If both materials are wood, apply primer to both surfaces of the wood in the same way. When the adherend is a plus book, metal, etc., it is not necessary to apply a primer made of an isocyanate compound, but if necessary, a dedicated primer can be applied for each. Particularly when the adherend is metal, it is preferable to apply a silane compound to improve water resistance.

A polyester resin adhesive is then applied.

Specifically, using an applicator, apply molten adhesive to one or both surfaces of the stone material,
Crimp both. If the aforementioned primer has been applied in advance, apply molten resin to the applied surface. When the shape of the adherend is plate-like or sheet-like, a method can be adopted in which a film-like adhesive is inserted between the two adherends and the adhesive is heated and pressed using a heating roll or the like.

The coating amount of Fosotomel 1 to adhesive is 30 to 300 (+/foot, preferably 1.1100 to 1501)/m.

The heating temperature is set to be slightly higher than the melting point of the polyester resin constituting the adhesive, but it is determined as appropriate in consideration of the viscosity of the resin in the molten state. Pressure force is 0.5 to 10 9/
crN! It is considered to be 1 degree and the shape of the adherend.

It is determined by taking into account the amount of adhesive applied, the melt viscosity of the adhesive, etc. The crimping time is the time it takes for the adhesive to harden, and it depends on the type of adherend, the amount of adhesive applied, etc.
Usually, 0.3 to 3 seconds is sufficient.

[Effect]

According to this adhesion method, a primer made of an isocyanate compound is applied to the surface of the wood to be adhered, so
The 11 active groups of the isocyanate compound react with moisture on the surface of the wood, making the surface of the wood resin-reinforced. As a result, swelling of the surface of the wood to which it is attached due to moisture is prevented, and water resistance is improved. In addition, the isocyanate compound of the primer has good affinity with the polyester resin, and since a certain degree of reaction between the residual isocyanate groups and the polyester end groups can be expected, the adhesive strength under normal conditions also increases.

[Experiment example]

Below, we will show experimental examples to clarify the effects.

(Experimental Example 1) As a hot melt type polyester resin adhesive, a copolymer of dimethyl terestalate and 1,4-butanediol was used.

Asahi Kasei Kogyo Co., Ltd.) was used as a primer, and a solution of a prepolymer made of polysocyanate and polyester, which were prepared by adding 1-diisocyanate to a polyhydric alcohol, dissolved in methylene chloride, was used to cover the adherend. Using the pieces, the compressive shear adhesive strength was determined according to JIS-6801. For comparison, general FVA resin Hot 1 Hemel 1
A similar test was conducted using two types of adhesives and the above-mentioned brimer.

The results are shown in Table 1.

-〇- (Experiment Example 2) Using the adhesive and braimer of Experiment Example 1, plywood (thickness 1
A band-shaped sheet 1~ of diallyl phthalate resin-impregnated paper (thickness: 0.3 mm) was adhered to the end face of the sheet (#5). Use this adhesive in high humidity! ii! (40° C., 90% RH) for 14 days, an accelerated durability test was conducted, and performance was evaluated based on adhesive peeling rate. The results are shown in Table 2.

From these experimental results, it was found that the brimer greatly improves water resistance, and that the polyester resin adhesive itself has higher water resistance than conventional EVA adhesives, and the combination of these results in an extremely high shielding force. It can be seen that the water resistance is 19.

〔Effect of the invention〕

As explained above, the wood adhesion method of the present invention uses a hot-melt polyester resin adhesive as an adhesive and an isocyanate compound as a primer.
The isocyanate compound in the primer hardens the structure of the wood surface to which it is attached, preventing swelling of the structure due to moisture, and since polyester resin, which is inherently water resistant, is used, it exhibits extremely high water resistance. Furthermore, since the isocyanate compound of the brimer has a high affinity with the polyester resin, it exhibits high adhesive strength even under normal conditions. Furthermore, since it is a hot melt type, the assimilation time is only a few seconds.
It has the advantage of being able to perform high-speed bonding work and improving productivity.

Claims (1)

[Claims] A wood bonding method characterized by using a hot-melt polyester resin adhesive as an adhesive and an isocyanate compound as a primer.