JP2895429B2 - Adhesive for air-permeable adherend and bonding method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive mainly composed of an isocyanate compound, which is cured by heating and moisture, and a method for bonding the same. More specifically, it is made of a permeable and moisture-containing wood, a lignocellulose material, an inorganic material, etc., and is suitable for bonding an adherend having a non-smooth adhesive surface and an uneven thickness. The present invention relates to a body bonding adhesive and a bonding method using the same.

[0002]

2. Description of the Related Art As an adhesive for adhering adherends of wood or lignocellulose material, aqueous solutions of urea resin adhesive, melamine resin adhesive, phenol resin adhesive, etc., and polyvinyl acetate resin An adhesive comprising an aqueous emulsion such as a polyacrylate resin is known. Each of these adhesives is used in a state of being dissolved or emulsified in water, and its concentration is at most 75% or less, generally 40 to 50%. Although these adhesives are easy to produce and are advantageous in cost, they have poor adhesive performance, particularly poor water resistance, and have problems such as formaldehyde odor, so their use is limited.

[0003] On the other hand, an isocyanate-based adhesive is known as the adhesive for an adherend. This isocyanate-based adhesive does not use formalin, and exhibits excellent adhesive performance by reacting with a hydroxyl-containing component contained in wood and the like, and generally has excellent water resistance, heat resistance, durability, and impact resistance. Due to its superiority and the like, its usage has been gradually increasing in recent years. Examples of this type of isocyanate-based adhesive include, for example, JP-B-51-30577 and JP-B-57-22.
959 and JP-B-58-29826 each disclose an adhesive having an aqueous emulsion as a main component and having excellent water resistance. These adhesives are prepared by mixing an isocyanate compound with an aqueous emulsion containing an aqueous solution such as polyvinyl alcohol, or by reacting with a small amount of a polyol in advance and emulsifying in water,
Usually, it is a water suspension having a concentration of the adhesive of 50% or less. In addition, since these adhesives are water-based and contain almost no organic solvent, they have the advantage that there are few volatile substances harmful to the human body and there is no danger to fire.

[0004] However, the isocyanate-based adhesive has a relatively short usable time (hereinafter referred to as a pot life) and contains a large amount of water in the adhesive. However, the curing time was required to be sufficiently long, so that there was a problem in workability. In addition, adherends such as wood, lignocellulosic materials, and inorganic materials also contain moisture, and when the moisture content is high, the adhesive may permeate during bonding or the contained moisture may be heated. In some cases, the air layer was evaporated, and the resulting air layer was punctured by the applied pressure to cause poor adhesion. In particular, for wood-based materials,
There are problems such as warpage and cracking of the adherend surface due to expansion and contraction due to moisture.

In order to solve these problems, a one-part, moisture-curable polyurethane adhesive is disclosed in, for example,
No. 792, and two-component curing type polyurethane adhesives are disclosed in, for example, JP-A-3-244687, JP-A-4-298593, and JP-A-5-170858.
Nos. 2, pp. 3 and 4, respectively. Since the above polyurethane adhesives contain almost no water or organic solvent, both of the above-mentioned problems in the working environment and the problem of poor adhesion due to water are solved.

[0006]

However, since the above polyurethane adhesive is a moisture-curing type made of a prepolymer of an isocyanate compound, the curing speed is generally slow, and it usually takes several days to completely cure the polyurethane adhesive. There was a problem with workability. Further, shortening the curing time lowers the storage stability and the pot life, so that it was difficult to satisfy all of the curing time, the storage stability and the pot life.
Since the above polyurethane adhesive is a two-part curing type made of a prepolymer of an isocyanate compound, it can be cured at a low temperature or for a short time, but is made of a polyol having a high hygroscopicity or a polyol having a high molecular weight and a high viscosity. For this reason, among the adhesive properties, the water resistance is particularly deteriorated, and the resin itself, which occupies most of the adhesive, is expensive. In addition, these prepolymers easily penetrate into the adherend, and as a result, the adhesive layer becomes thin and the bonding performance becomes unstable, and there is also a problem that a high-pressure pressing is required. In particular, an adherend having a lack of smoothness and an uneven thickness, such as a lignocellulose material such as wood or annual plant stem, or an inorganic material such as a cement plate, a calcium silicate plate, or a gypsum board Since many of the bodies are porous, when these adherends are bonded using the above-mentioned adhesive, the adhesive rapidly penetrates into the adherend when the adhesive is applied,
The adhesive layer was likely to be thin, or to be in a so-called glued state in which no adhesive was present on the adhesive surface. For this reason, a relatively large amount of adhesive must be applied to the adherend, and it is necessary to perform pressure bonding at a high pressure during bonding. Sometimes it happened.

For the purpose of reducing the apparent cost of the polyurethane adhesive as an adhesive,
When fillers such as clay, calcium carbonate, and wood powder are added, or when cereal flour such as flour is added as a bulking agent, the water contained in the bulking agent and the bulking agent reacts with the isocyanate compound. In addition, there are problems such as lowering storage stability, low molecular weight of polyurethane resin, and lowering of adhesive strength due to foaming during curing. In particular, when the filler or extender is added in an amount of 30 parts by weight or more with respect to 100 parts by weight of the adhesive aqueous solution or the aqueous emulsion, the filler or the extender is separated or the viscosity of the adhesive aqueous solution or the aqueous emulsion is reduced. There was a problem that it became extremely difficult to handle it. Among the above, the polyurethane adhesives described in JP-A-4-298593 and JP-A-5-170858 are known to contain calcium oxide in the filler in order to avoid a decrease in adhesive strength due to foaming during curing. , Magnesium oxide and barium oxide are added to prevent foaming during curing. Other methods for preventing foaming include a method of heating and drying a filler, a method of adding a zeolite having a limited component and structure to an uncured composition (Japanese Patent Publication No. 48-33731), an isocyanate compound to be used, A method of limiting a polyol compound (JP-A-54-126297) and the like are known. However, these methods for preventing foaming are insufficient, the adhesive component is limited, or the cost of the adhesive is increased.

An object of the present invention is to bond an adherend made of wood, a lignocellulose material, an inorganic material, etc., which is breathable and has moisture, has good storage stability, and has a usable life. An object of the present invention is to provide an adhesive for a gas-permeable adherend that is long, has excellent curability, and has high adhesive strength. Another object of the present invention is to provide an adhesive for a gas-permeable adherend which does not require a dehydration treatment and does not reduce the adhesive strength due to a foaming action during curing. Still another object of the present invention is to apply to an adherend having air permeability and moisture, made of wood, a lignocellulose material, an inorganic material, etc., having a lack of smoothness and an uneven thickness on an adhesive surface. It is an object of the present invention to provide an adhesive for a gas-permeable adherend which can obtain high adhesive strength by pressing at a relatively low temperature and pressure without increasing the amount, and an adhesive method using the same.

[0009]

The invention according to claim 1 is
An adhesive for adhering a gas-permeable and water-containing adherend, which is 100 parts by weight of a room temperature liquid compound having at least two isocyanate groups in a molecule, and 9
It is characterized by containing 1 to 15 parts by weight of a foaming agent that generates a gas when heated to a temperature of 0 to 200 ° C., and 30 to 200 parts by weight of a filler. The isocyanate compound foams by reacting with moisture to suppress the penetration of the adhesive into the adherend and maintain the adhesive layer at a predetermined thickness. Even if this foaming occurs or gas is generated by the foaming agent, the air-permeable adherend absorbs the gas when pressed. Even if the adhesive surface lacks smoothness, the adhesive spreads over the adhesive surface with a small application amount by the foaming agent, and high adhesive strength can be obtained. When the adhesive of the present invention is prepared by mixing an isocyanate compound, a foaming agent and a filler, a part of the isocyanate compound reacts with moisture contained in the filler, so that a slight increase in viscosity is observed. However, the reaction rate with the moisture in the air is extremely slow, and long-term storage in a sealed state is possible.

The amount of the foaming agent is 1 to 15 parts by weight based on 100 parts by weight of the isocyanate liquid compound. If the amount of the foaming agent is less than 1 part by weight, there is no foaming effect, and if the amount is more than 15 parts by weight, the adhesive layer has too many air bubbles and the adhesive performance is reduced. The foaming agent is 90-20
Use what foams at a temperature of 0 ° C. Those that foam below 90 ° C will foam when the adhesive is compounded,
Increase the viscosity of the adhesive and shorten its pot life. 20
It is not preferable that the foaming temperature exceeds 0 ° C. because the heating temperature at the time of pressing the adherend must be higher than necessary and the adherend is thermally damaged at the time of pressing. The amount of the filler is 30 to 2 with respect to 100 parts by weight of the isocyanate liquid compound.
00 parts by weight. If the amount of the filler is less than 30 parts by weight, the isocyanate compound easily penetrates into the adherend, and the bonding performance becomes unstable. On the other hand, if the amount is more than 200 parts by weight, the flow state of the composition becomes poor, and uniform application to the surface of the adherend becomes impossible, and the adhesiveness becomes unstable.

The invention according to claim 2 is the invention according to claim 1, wherein the compound having at least two isocyanate groups in a molecule and having a reaction activity with an isocyanate group is 100 parts by weight of a liquid compound at room temperature. 0.5 more
An adhesive for a gas-permeable adherend containing up to 50 parts by weight. When a compound having a reaction activity with an isocyanate group is included, the reaction of the adhesive composition is promoted. The compounding amount of this compound is 0.5 to 50 parts by weight. If the compounding amount of this compound is less than 0.5 part by weight, the reaction is not sufficiently promoted, and
If the amount is more than 0 parts by weight, the reaction of the composition of the adhesive is excessively promoted, and the viscosity is rapidly increased, so that the pot life is significantly shortened.

The invention according to claim 3 is the invention according to claim 1 or 2, wherein the compound having at least two isocyanate groups in a molecule and being liquid at room temperature is a compound containing diphenylmethane diisocyanate as a main component. .
Diphenylmethane diisocyanate is excellent in viscosity characteristics and adhesive strength.

According to a fourth aspect of the present invention, there is provided a compound having at least two isocyanate groups in a molecule, which is 100 parts by weight of a liquid compound at room temperature and 1 to 15 parts by weight of a blowing agent which generates a gas when heated to a temperature of 90 to 200 ° C. And filler 30-200
Weight part of the adhesive for air-permeable adherends is applied to an air-permeable and water-containing adherend, and the adherend coated with the adhesive is heated at a temperature of 90 to 200 ° C. and a pressure of 1 to 20 kg / cm
^This is the bonding method of heating and pressing in ² . In the bonding method of the present invention, the isocyanate group reacts with moisture during bonding to foam while generating carbon dioxide gas, and the foaming agent expands during heating and pressing to form a dense and thick foamed adhesive layer. Part of the thick foamed adhesive layer fills the air holes of the adherend and the rest covers the adhesive surface, and even the uneven adhesive surface is smoothed. As a result, the adhesive is moored to the inside of the adherend and spreads all over the adhesive surface, so that a large adhesive strength is obtained. The air holes in the adherend are useful for discharging gas generated during curing of the adhesive to the outside, or for allowing moisture in the air to reach the adhesive layer. When the adherend having moisture is adhered by the adhesive of the present invention, and when the amount of moisture is small, when the adherend is adhered in the presence of water, the curing of the adhesive is accelerated.
Similarly, when a compound having a reaction activity with an isocyanate group is included in the adhesive, the curing of the adhesive is also promoted.

In the bonding method of the present invention, the adhesive of the present invention is applied and then heated and pressed using a hot press or the like. In this case, it is necessary to adjust the pressing pressure to such an extent that a gap in the adherend remains to some extent. When using a hot press, inserting a spacer between the hot plates is effective for this purpose. When the adherend is a plant stem, a wood chip, or the like, the preferable pressing pressure is preferably adjusted so that the product specific gravity is 0.5 or less. Generally, the bonding strength is slightly reduced with a decrease in the pressing pressure. However, when the pressure is lower than a certain pressure, the bonding strength is extremely reduced, which causes poor bonding.
The limit is usually about 0.2 in terms of product specific gravity for these adherends. The pressing time depends on the temperature of the hot plate and the thermal conductivity of the material. Normally, the pressure can be released several minutes after the temperature of the adhesive layer reaches 100 ° C. or higher. If the temperature at the time of heating and pressing is less than 90 ° C., if the pressure is less than 1 kg / cm ² , the foaming agent does not foam and the adhesive strength is low, and if it exceeds 200 ° C., there is a problem that the adherend is thermally damaged at the time of pressing. . If the pressure at this time exceeds 20 kg / cm ² , the adherend may be broken depending on the adherend.

According to a fifth aspect of the present invention, there is provided a compound having at least two isocyanate groups in a molecule, which is 100 parts by weight of a liquid compound at room temperature and 1 to 15 parts by weight of a foaming agent which generates a gas when heated to a temperature of 90 to 200 ° C. And filler 30-200
Weight part of the adhesive for air-permeable adherends is applied to an air-permeable and water-containing adherend, and while the water vapor is sprayed onto the adhesive-coated adherend, the temperature of the adherend is raised. 90 ~
This is a bonding method in which heating and pressing are performed at 200 ° C. and a pressure of 1 to 20 kg / cm ² . At the time of hot-press bonding, when water vapor is further penetrated by spraying water vapor on the adherend at the same time as pressing,
In order for moisture to accelerate the curing of the isocyanate compound,
Bonding can be completed with a shorter pressing time.

[0016] The invention according to claim 6 is the invention according to claim 4 or 5, wherein the adherend is impregnated with a compound having a reaction activity with an isocyanate group, and then the air-permeable adherent for adherend is removed. This is a bonding method applied to an adherend. By impregnating the adherend with the above compound, the compound having an isocyanate group reacts more effectively on the adhesive surface.

The invention according to claim 7 is the invention according to claims 4 to 6
Any one of the inventions is a bonding method in which the adherend has a moisture content of 2 to 25%. When about 2 to 25% of water is contained in the adhesion surface or inside of the adherend, it is effective to accelerate the curing of the adhesive. If it is less than 2%, the curing is not accelerated, and if it exceeds 25%, there occurs a problem that the adhesive strength is reduced.

The invention according to claim 8 is the invention according to claims 4 to 7
Any of the inventions, wherein the adhesive is applied in the presence of water at the time of adhesion, and the amount of water present is 20 parts by weight based on 100 parts by weight of a room temperature liquid compound having at least two isocyanate groups in a molecule. The following is the bonding method. Although the adhesive of the present invention is sufficiently cured only by the moisture contained in the adherend, when the amount of moisture is very small, or in order to make the curing more efficient, the adhesive is applied to the adhesive before adjusting the viscosity. A small amount of water can be added to the mixture. Normally, when water is added to an isocyanate compound, it is difficult to uniformly disperse the isocyanate compound and water irrespective of the addition amount, since the isocyanate compound and water are separated. However, the adhesive of the present invention can relatively easily disperse water in the isocyanate compound by including the filler. Although the addition of water brings about a reduction in the pot life, the workability and the adhesion to the adherend can be improved by adjusting the viscosity to an optimum value according to the application method and the type of the adherend. it can. Also, by adding a small amount of water, the curing of the adhesive is promoted. The amount added is usually based on 100 parts by weight of the isocyanate compound.
It is within the range of 20 parts by weight or less, preferably 10 parts by weight or less, more preferably 1 to 5 parts by weight. If more than 20 parts by weight of water is added, the viscosity increases rapidly and the pot life is significantly shortened.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. (A) adherend The adherend adhered with the adhesive for air-permeable adherend of the present invention,
It is made of wood having breathability and moisture, lignocellulosic material, inorganic material and the like. Examples of the adherend of wood include veneer, plywood, laminated veneer and lumbar, particle board, fiberboard such as MDF (Medium Density Fiber Board), and various woody molded materials. Preferable adherends of the lignocellulose material include plant stems such as tall stalks, corn stalks, sugarcane stalks, bamboos and the like, crushed products thereof, and wood chips. In particular, the high pemphigus is difficult to adhere with a conventional adhesive due to the wax component of the epidermis, but is preferred as the adherend of the present invention because it satisfies all the above conditions. Examples of the inorganic material include a cement plate, a calcium silicate plate, a magnesium carbonate plate, a gypsum board, a glass fiber mat, and a slag board.

The adherend is not limited to a sheet, plate or block, but includes a chip. In the case of an adherend other than a chip-shaped object and two or more adherends are overlapped and bonded,
It is preferable that the two adherends satisfy the above conditions,
If one of the two adherends satisfies the above conditions, the other adherend may be a non-permeable or water-free metal plate such as aluminum or lead, or melamine. It is possible to select plastic films, plates and foams such as polyester, urethane and the like.
In this specification, the state of the adherend having air permeability and moisture refers to the state of the adherend before applying the adhesive, and refers to the state of the adherend after the adhesive is cured. is not. The state having air permeability refers to a state in which the adherend has pores to such an extent that the adhesive does not remain in a foamed state between the adhered surfaces of the adherends which have been applied and then adhered and pressed together.

(B) Room temperature liquid compound having at least two isocyanate groups in the molecule The room temperature liquid compound having an isocyanate group used in the present invention includes tolylene diisocyanate, diphenylmethane diisocyanate (hereinafter referred to as MDI). Such as xylylene diisocyanate, hexamethylene diisocyanate, naphthalene diisocyanate, etc., having at least two isocyanate groups of the same type in the molecule and maintaining a liquid state at room temperature (including various isomers of monomeric and polymeric). Or a mixture containing one or more compounds selected from these compounds.

The viscosity of these compounds or mixtures is 0.5
It is desirable to be in the range of ~ 20 poise. The viscosity is 0.
If it is lower than 5 poise, the adhesive will penetrate into the adherend intensely and the bonding performance will be unstable. If the viscosity exceeds 20 poise, it becomes difficult to add fillers and extenders to the required amounts, and the pot life of the adhesive becomes extremely short. Among the above compounds, polymeric MDI composed of a polynuclear mixture of various MDI isomers and several multimers thereof is particularly preferable in terms of viscosity characteristics and adhesive strength. Prepolymers of isocyanate compounds obtained by reacting these isocyanate compounds with various polyols and the like are generally not preferred because they generally have high viscosities, require viscosity adjustment by addition of a solvent, and have reduced storage stability.

(C) Foaming agent The foaming agent used in the present invention is preferably at a temperature of 90 to 200 ° C. which does not react with isocyanate groups,
Any material that foams when heated to a temperature of 00 to 150 ° C may be used. Examples include carbonates such as ammonium carbonate, bicarbonates such as sodium bicarbonate, azo compounds such as azobisisobutyronitrile, and hydrazide compounds such as benzenesulfonyl hydrazide. A foaming agent having a thermal decomposition temperature of 150 ° C. or less is preferable.

(D) Filler The filler used in the present invention includes: a) carbonates such as clay, bentonite, calcium carbonate and magnesium carbonate; a) calcium compounds such as calcium sulfate and calcium silicate; c) Metal oxides or hydroxides of aluminum, zinc, magnesium, iron, etc., d) carbon,
Glass, inorganic powder such as mica or fibrous material, e)
Wood flour, coconut shell flour, firgrass, mosquitoes, stalk powders such as corn, high rye, etc., ki) seed hull powders such as walnuts, peaches, etc. Proteins and starchy substances. If necessary, a flame retardant, a coloring pigment, a thickener, a lubricant and the like can be added.

If the filler used in the present invention has a natural water content, it is not necessary to previously heat-dry or dehydrate it. As the filler, one kind may be blended, or a plurality of kinds may be mixed. Mixing fillers having different particle sizes is effective in preventing the settling of the filler. Among the above-mentioned fillers, calcium carbonate is inexpensive and relatively easily available, contains moderate moisture,
Because of its good reactivity with isocyanates, it is suitable as a filler in the present invention.

(E) Compound having a reaction activity with an isocyanate group The compound having a reaction activity with an isocyanate group used in the present invention is a compound having a hydroxyl group, an amino group, an imino group, a carboxyl group and the like. Specifically, a)
Diols such as ethylene glycol and propylene glycol; a) triols such as glycerin; c) tetraols such as pentaerythritol and oxypropylated ethylenediamine; d) amines such as hexamethylenediamine and triethanolamine; e) Polyvinyl alcohol, polyethylene imine, melamine resin,
Water-soluble polymers such as phenolic resins and starch,
Resins such as vinyl acetate resin, acrylate resin, polyester resin, vinyl chloride resin, etc.)
One or more rubbers selected from rubbers such as butadiene rubber are used.

[0027]

As described above, the adhesive for a gas-permeable adherend of the present invention is a non-aqueous adhesive mainly containing an isocyanate compound as compared with a conventional aqueous adhesive. It does not react until it comes into contact with the moisture contained in the body, thereby significantly increasing the pot life. For this reason, the adhesive of the present invention has storage stability, and after being applied to an adherend,
Even if left for up to 3 days, almost no decrease in adhesion performance due to dry adhesion is observed. Therefore, it is possible to apply the adhesive to the adherend collectively in advance, which significantly contributes to lowering the bonding failure rate and increasing the efficiency of the bonding operation. Since the adhesive of the present invention is non-aqueous and takes in water in the reaction, when the water content of the adherend is as high as 2 to 25%, the conventional water-based isocyanate-based adhesive cannot be bonded. In addition, the adhesive of the present invention can be bonded.

The adhesive of the present invention does not foam even after being left for a long time, and the viscosity of the adhesive does not increase.
For this reason, by including a foaming agent that foams by heating, the foaming rate of the adhesive layer can be arbitrarily controlled at the time of heating and pressing, resulting in an adhesive having excellent void filling properties. As a result, the pressure at the time of bonding can be made lower than before, for example, 3 to 5 kg / cm ² , which is suitable for bonding an easily adhered adherend and lowering the specific gravity of the bonded object. For example, according to the method of the present invention, if the entire adherence of the stem of an annual plant such as high starch having a large amount of voids and a high moisture content is adhered to the adherend, a light-weight adherent adhered with high strength can be obtained. can get. According to the adhesive of the present invention, it can be used for bonding adherends having a higher moisture content, such as fiberboard and various wood-based molding materials, which is effective for improving yield and productivity, and realizes weight reduction of the bonded product. it can.

The adhesive of the present invention effectively acts on both the moisture of the filler and the moisture of the adherend contained in the adhesive.
Unlike a conventional polyurethane resin-based adhesive, there is no need to previously dehydrate a filler or an adherend. When wood materials are bonded using a steam injection press, the curing of the adhesive of the present invention is promoted by water vapor, and bonding can be performed by heating and pressing in a shorter time. Further, when water vapor is sprayed, excessive penetration of the adhesive is suppressed, and the adhesive performance is further improved.

[0030]

Next, examples of the present invention will be described together with comparative examples. <Examples 1-4> 100 parts by weight of MDI (manufactured by Nippon Polyurethane Co., Ltd., trade name: MR-400) were mixed with 100 parts by weight of calcium carbonate powder and 5 parts by weight of water as a filler, and further foamed. Table 1 shows calcium bicarbonate powder as an agent
In the amount shown in Table 1 to prepare an adhesive size liquid. This adhesive was left in a room at 24 ° C. for 3 hours while rotating the roll on a roll spreader. Thereafter, the viscosity of the size liquid was measured. As a result, the viscosity was not changed from the initial viscosity, and there was no change in the size of the size liquid. Next, this adhesive was previously impregnated with a phenol resin at a solid content of about 20%, and a plurality of 45 cm long tall spikes were arranged in parallel, and both sides of a sheet tied in a cord form with 150 g each were 150 g. / Cm ² , and a stalk sheet coated with an adhesive in the same manner as above so that the stalks are perpendicular to each other. % Of radiatapine single veneer. In this state, it is inserted into a hot press maintained at 150 ° C. and pressurized at a pressure of 8 kg / cm ² for 18 hours.
The plate was hot-press bonded for 25 minutes to obtain a thick plate having a thickness of 25 mm.

<Comparative Example 1> An adhesive paste was prepared in the same manner as in Example 1 except that no foaming agent was blended, and the adhesive was applied in the same manner as in Example 1 and the same as in Example 1. A thick plate was prepared.

<Comparative Example 2> An adhesive paste was prepared in the same manner as in Example 1 except that 20 parts by weight of the foaming agent was blended, and this adhesive was applied in the same manner as in Example 1 and the same as in Example 1. A thick plate was prepared.

The obtained slabs of Examples 1 to 4 and Comparative Examples 1 and 2 were tested in accordance with the test method specified in JIS A 5908, and after immersion in boiling water for 2 hours, average normal bending strength. The thickness swelling ratio and the peel strength were measured. Table 1 shows the results.

[0034]

[Table 1]

As is clear from Table 1, in Examples 1 to 4, each of the thick plates had a bending strength of 128 kgf / cm ² or more, was strong and had a thickness swelling ratio of less than 7.0%. The performance was excellent. Although the bending strength in Comparative Example 1 with respect to this was strong and 130 kgf / cm ^2, in Comparative Example 2 1
It was less than 00 kgf / cm ² , and the thickness swelling ratio of both Comparative Examples 1 and 2 exceeded 7.0%. The adhesive strength of Comparative Examples 1 and 2 was 2 kgf / cm ² or less, while Examples 1 to 4 were 2.4 kgf / cm ² or more. Further, while Comparative Example 2 having a large amount of the foaming agent was broken from the value of the wood breaking ratio on the adhesive-coated surface, the other Examples 1 to 3 were broken.
In Comparative Example 4 and Comparative Example 4, it was found that 78% or more of them were broken at the veneer portion and were strongly bonded.

Example 5 MDI (Nippon Polyurethane)
100 parts by weight of a calcium carbonate powder as a filler, 10 parts by weight of a calcium bicarbonate powder as a foaming agent and 5 parts by weight of water with respect to 100 parts by weight of an adhesive. A size liquid was prepared. Apply this adhesive to 2
The roll was allowed to stand on a roll spreader in a room at 4 ° C. for 3 hours while rotating. Thereafter, the viscosity of the size liquid was measured. As a result, the viscosity was not changed from the initial viscosity, and there was no change in the size of the size liquid. Next, this adhesive was applied to both surfaces of a 1.8 mm-thick radiatapain veneer having a moisture content of 18% at a rate of 180 g / m ² per adhesive layer. Ply plywood was made. Adhesion conditions at this time were a temporary pressure clamping at a pressure of 3 kg / cm ² for 30 minutes, and thereafter, a pressure of 6 kg / cm ² at a temperature of 130 ° C. for 3 minutes to perform adhesion.

Comparative Example 3 20 parts by weight of flour and 5 parts of water were used as fillers based on 100 parts by weight of a commercially available melamine-urea co-condensation resin adhesive (trade name: ML-044, manufactured by Honen Corporation). Parts by weight and 0.5 parts by weight of ammonium chloride powder were blended to prepare an adhesive size liquid. This adhesive paste liquid was left in a room at 24 ° C. for 3 hours while rotating the roll on a roll spreader. Thereafter, the viscosity of the size liquid was measured, and as a result, the viscosity was increased to 2.6 times the initial viscosity. Next, this adhesive was applied to both surfaces of the same radiatapain veneer as in Example 5 at a rate of 180 g / m ² per adhesive layer, and radiatapain veneers having the same thickness were further laminated, and the same conditions as in Example 5 were applied. By bonding with
A three-ply plywood was prepared. The obtained plywoods of Example 5 and Comparative Example 3 were each subjected to an adhesive strength test prescribed in JAS standard plywood class I standards. Table 2 shows the results.

[0038]

[Table 2]

As is clear from Table 2, the adhesive strength of Example 5 was about 2.7 times that of Comparative Example 3. Also, from the value of the wood fracture ratio, it was found that Comparative Example 3 was broken on the surface coated with the adhesive, whereas in Example 5, 87% of the broken wood was broken on the veneer portion, and the bonding was firm.

Example 6 MDI (Nippon Polyurethane)
30 parts by weight of xylidene diisocyanate (trade name: Takenate 500, manufactured by Takeda Pharmaceutical Co., Ltd.) was uniformly mixed with 70 parts by weight of a trade name: MR-400 (trade name, manufactured by K.K. An adhesive paste liquid was prepared by uniformly mixing 50 parts by weight of calcium powder and 50 parts by weight of flour, 5 parts by weight of calcium bicarbonate powder, 5 parts by weight of ammonium carbonate, and 5 parts by weight of water as a foaming agent. Apply this adhesive to
The roll was rotated on a roll spreader in a room at 8 ° C. and left for 3 hours. Thereafter, the viscosity of the size liquid was measured. As a result, the viscosity was not changed from the initial viscosity, and there was no change in the size of the size liquid. Next, this adhesive was applied to both sides of a sheet in which a number of 45 cm long tall spikes preliminarily impregnated with a phenol resin at a solid content ratio of about 45 cm were arranged in parallel and tied together in a cord-like manner. After applying at a rate of 150 g / cm ² , a stalk sheet coated with an adhesive in the same manner so that the stalks are orthogonal to each other is superimposed on the stalk sheet. 5% radiatapine single veneers were overlaid. In this state, the plate was inserted into a hot press maintained at 150 ° C., and was hot-pressed at a pressure of 8 kg / cm ² for 18 minutes to obtain a thick plate having a thickness of 25 mm.

Example 7 MDI (Nippon Polyurethane)
90 parts by weight of clay powder and 10 parts by weight of flour as fillers, 10 parts by weight of azobisisobutyronitrile as a foaming agent, and ethylene / acetic acid, based on 100 parts by weight of trade name, manufactured by Co., Ltd. 20 parts by weight of a vinyl copolymer resin emulsion were uniformly blended to prepare an adhesive paste liquid. The adhesive was uniformly applied by spraying to a plywood waste chip dried to a moisture content of 5 to 6% so as to have a solid content weight ratio of 7%. Next, the plywood waste chips are made into a uniform thickness, and inserted into a hot press maintained at 180 ° C.
Apply a pressure of 0 kg / cm ² and squeeze for 3 minutes.
The plate was pressed at a pressure of kg / cm ² for 3 minutes to form a thick plate having a thickness of 20 mm.

For each of the thick plates of Examples 6 and 7, JIS
The test was performed according to the test method specified in A5908 (particle board), and the specific gravity, average normal bending strength, and thickness swelling ratio after immersion in boiling water for 2 hours were measured.
Table 3 shows the results.

[0043]

[Table 3]

As is clear from Table 3, Examples 6 and 7
Each of the thick plates had a bending strength exceeding 130 kgf / cm ² , a thickness swelling ratio of less than 7.5%, and was excellent in performance as a thick plate.

<Example 8> 140 parts by weight of a clay powder as a filler and 5 parts by weight of ammonium carbonate as a foaming agent are based on 100 parts by weight of MDI (manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name: Sumidur 44V). Was uniformly mixed to prepare an adhesive size liquid. This adhesive was applied in a room at 21 ° C while rotating the roll on a roll spreader for 3 hours.
Left for hours. Thereafter, the viscosity of the size liquid was measured. As a result, the viscosity was not changed from the initial viscosity, and there was no change in the size of the size liquid. Next, this adhesive was applied at a rate of 150 g / cm ^{2 on} both sides of a sheet in which a number of high-pitched stems having a length of 45 cm were arranged in parallel and tied with strings in a cord-like manner. Were overlapped with each other in five layers in the same manner so as to be orthogonal to each other, and a high-pressure melamine resin plate having a thickness of 1.0 mm was further laminated on the front and back surfaces. In this state, the laminate was inserted into a steam injection type hot press maintained at 150 ° C., and was pressed at a pressure of 5 kg / cm ² for 1 minute, and immediately thereafter, steam pressurized to 5 kg / cm ² was sprayed onto the laminate for 30 seconds. Further, after pressing was continued for 2.5 minutes at the same temperature, the pressure was reduced for 3 minutes to remove water from the laminate, and the laminate was taken out of the hot press to obtain a thick plate having a thickness of 40 mm. The surface of the obtained thick plate was made of a melamine resin plate, was smooth and could be used as it was as a table top plate.

<Example 9> 140 parts by weight of a clay powder as a filler and 5 parts by weight of ammonium carbonate as a foaming agent were uniformly mixed with 100 parts by weight of MDI (manufactured by Koyo Sangyo Co., Ltd., trade name: AP). The mixture was blended to prepare an adhesive size liquid. The adhesive was left for 3 hours while rotating the roll on a roll spreader in a room at 21 ° C. Thereafter, the viscosity of the size liquid was measured. As a result, the viscosity was not changed from the initial viscosity, and there was no change in the size of the size liquid. Next, apply this adhesive to length 45
cm on the both sides of a sheet in which a number of tall spikes are arranged in parallel and tied in a cord-like manner with a thread at a rate of 150 g / cm ^2. The stem sheet to which the adhesive was applied by the method was superimposed on five layers, and further, a gypsum board having a thickness of 12.5 mm was superimposed on the front and back surfaces. In this state, it was inserted into a steam injection hot press maintained at 150 ° C.
Immediately after pressing for 1 minute at a pressure of g / cm ² 5kg / cm ²
Was sprayed onto the laminate for 30 seconds. Further, after pressing was continued at the same temperature for 6 minutes, the pressure was reduced for 4 minutes to remove moisture from the laminate, and the laminate was taken out of the hot press to obtain a thick plate having a thickness of 90 mm. The surface of the obtained thick plate was made of gypsum board, and there was no change such as cracks or cracks on the surface, and the plate could be used as a wall panel material as it was.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C09J 175/04 C08G 18/30 C09J 5/06

Claims (8)

(57) [Claims] 1. An adhesive for bonding an adherend having air permeability and moisture, comprising 100 parts by weight of a room temperature liquid compound having at least two isocyanate groups in a molecule, and 90 to 200 parts by weight. An adhesive for a gas-permeable adherend, comprising 1 to 15 parts by weight of a foaming agent which generates a gas when heated to a temperature of ° C, and 30 to 200 parts by weight of a filler. 2. A compound having at least two isocyanate groups in a molecule and having a reaction activity with an isocyanate group per 100 parts by weight of a liquid compound at room temperature which is at room temperature.
The adhesive for a gas-permeable adherend according to claim 1, comprising 5 to 50 parts by weight. 3. A compound which has at least two isocyanate groups in a molecule and is liquid at room temperature is diphenylmethane.
The adhesive for a gas-permeable adherend according to claim 1 or 2, which is a compound containing diisocyanate as a main component. 4. A compound having at least two isocyanate groups in a molecule, which is a liquid at room temperature and 100 parts by weight,
A foaming agent that generates gas when heated to a temperature of 200 ° C.
An adhesive for air-permeable adherends containing 15 parts by weight and 30 to 200 parts by weight of a filler is applied to an air-permeable and moisture-containing adherend, and the adherend coated with the adhesive is heated to a temperature of 90. A bonding method of heating and pressing at a temperature of 200 ° C. and a pressure of 1 to 20 kg / cm ² . 5. A compound which has at least two isocyanate groups in a molecule and which is liquid at room temperature and is 100 parts by weight,
A foaming agent that generates gas when heated to a temperature of 200 ° C.
An adhesive for air-permeable adherends containing 15 parts by weight and 30 to 200 parts by weight of a filler is applied to an air-permeable and water-containing adherend, and water vapor is applied to the adherend to which the adhesive has been applied. The temperature of the adherend is 90 to 200 ° C. and the pressure is 1 to 20 kg / c while spraying.
bonding method of heating pressing in m ^2. 6. The bonding method according to claim 4, wherein the adherend is impregnated with a compound having a reaction activity with an isocyanate group, and then an adhesive for a gas-permeable adherend is applied to the adherend. 7. The bonding method according to claim 4, wherein the adherend has a water content of 2 to 25%. 8. Attachment is carried out in the presence of water, and the amount of water present is not more than 20 parts by weight per 100 parts by weight of a room temperature liquid compound having at least two isocyanate groups in the molecule. The bonding method according to claim 4.