JPH05214306A - Rapidly curable aqueous adhesive and method for bonding - Google Patents

Abstract

PURPOSE:To provide a separately two liquid-coating type rapidly curable aqueous adhesive giving highly improved adhesive forces. CONSTITUTION:The adhesive comprises (A) a component A comprising the aqueous solution and/or the aqueous emulsion of a polymeric compound and (B) a component comprising a mixture containing a curing agent and fine particles directly not reacting with the curing agent. The polymeric compound includes polyvinyl alcohol (hereinafter referred to as PVA), a modified PVA, polyacrylic acid and its alkali salt. The aqueous emulsion includes a natural rubber latex and a styrene/butadiene rubber latex. The curing agent in the component B includes monoaldehydes such as formaldehyde, acetaldehyde and benzaldehyde without being especially limited. The fine particles directly not reacting with the curing agent are preferably ones which have large surface surfaces, respectively, are porous and are insoluble or swellable in water at <=60 deg.C, such as corn starch or potato starch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fast-curing water-based adhesive and a bonding method. More specifically, the present invention relates to a two-liquid fractional-coating type quick-setting water-based adhesive suitable for adhesion of wood, paper, inorganic materials and the like, and an adhesion method.

[0002]

2. Description of the Related Art Heretofore, polyvinyl acetates, starches, polyvinyl acetate emulsions, urea resins, rubber resins, epoxy resins, isocyanate compounds and the like have been used for such adhesives. However,
Except for the adhesive made of rubber resin, the initial adhesive strength is poor, and since the rubber resin adhesive also uses a large amount of organic solvent, there is toxicity and risk of fire, and it is easy to age. There are drawbacks.

Therefore, various studies have been carried out in order to improve these drawbacks, for example, a main agent consisting of an aqueous solution and / or an aqueous emulsion of a polymer compound having an acetoacetyl group in the molecule, an aldehyde compound, an isocyanate compound, polyethyleneimine. , A two-pack type quick-curing adhesive comprising a hydrazine compound curing agent (Japanese Patent Laid-Open No. 1-60190).
No. 60192), a two-component type quick-setting water-based adhesive composed of a polymer emulsion containing an imide group and a compound having an aldehyde group (JP-A-60-53575), and the like.

[0004]

These fast-curing pressure-sensitive adhesives exhibit their effects only when the main agent and the curing agent are in an ideal mixed state. However, the main agent and the curing agent can only come into contact with each other on the surface of the main agent, and it is very difficult to penetrate to the inside, and particularly when using a porous base material such as Lauan material or a concave portion of the base material. In that case, poor mixing of both components is likely to occur, which causes a decrease in adhesive strength and partial interface failure to cause interfacial peeling.

Therefore, in practice, in order to obtain a good mixed state of the main agent and the curing agent, work such as shifting the bonded adhesive surfaces to each other vertically and horizontally is performed. Since the gelation time after contact is extremely short, it is rare that an ideal mixed state can be obtained even in such an operation. Furthermore, the curing agent is usually applied as an aqueous solution to the adherend, but it is often used as a dilute solution due to its limited solubility in water. As a result, there are shortcomings such as lack of necessary curing agent or drying of the curing agent in advance in order to strengthen the initial adhesive force. Even in the case of an agent, it is the present situation that the excellent properties of the agent are not sufficiently exhibited in the product.

[0006]

However, the present inventors have
As a result of intensive research to solve such problems, (a)
A fast-curing adhesive consisting of an A component (B) curing agent consisting of an aqueous solution and / or an aqueous emulsion of a polymer compound and a B component consisting of a mixture containing fine particles that do not directly react with the curing agent is suitable for the purpose. This has led to the completion of the present invention. In the present invention, the necessary amount of the curing agent is exposed on the surface of the base material by mixing fine particles that do not directly react with the curing agent on the side of the curing agent of component B, and the coating surface of the curing agent becomes porous. Therefore, whether the component A is a locally concave surface of the base material or a locally thick coating state, it is possible to extremely easily penetrate into the deep part of the main agent. As they adhere to each other and are always ideally mixed, a very good adhesion state is obtained. Hereinafter, the present invention will be described in detail.

The polymer compound in the present invention means polyvinyl alcohol (hereinafter abbreviated as PVA) and modified PV.
A. Polyacrylic acid and its alkali metal salts. Acrylic acid copolymer. Copolymers of maleic anhydride and vinyl acetate, styrene, methyl vinyl ether, ethylene, propylene, isobutylene, etc. Water-soluble polyester. Polyacrylamide. Copolymers such as acrylamide and vinyl chloride. Polyvinylpyrrolidone. Water-soluble polyamine. Urea
Formaldehyde condensate. Synthetic polymers such as resorcinol-formaldehyde condensates. Starch and its chemically modified products. Examples include natural or semi-synthetic polymers such as carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose,
In particular, an aqueous solution and / or an aqueous emulsion of a polymer compound containing an acetoacetyl group is preferable in order to express initial adhesiveness and permanent adhesion strengthening, and as the aqueous solution and / or aqueous emulsion, an acetoacetyl group-containing polyvinyl alcohol ( Hereinafter, abbreviated as AA-PVA) is advantageous.

The AA-modified PVA can be produced by any method, but is preferably obtained by reacting PVA with diketene. For example, PVA is previously dissolved in a solvent such as dimethylformamide or dioxane, and diketene is added thereto. A method of directly contacting PVA with diketene gas or liquid diketene to obtain AA-PVA can also be adopted. P used to obtain AA-PVA
VA is not particularly limited, but the residual acetic acid group is 0.1 to 15 mol%, the average degree of polymerization is 300 to 2600, and the average degree of saponification is 85.
The range of 99 mol% is preferable. The AA degree of AA-PVA is 0.05 to 20 mol%, more preferably 0.05 to 1%.
A range of 5 mol% is suitable.

As the aqueous emulsion, natural rubber latex, styrene / butadiene latex, cis-1.
4 polyisobrene latex, chlorobrene latex, acrylonitrile / butadiene latex, vinyl pyridine latex, methyl methacrylate / butadiene latex, polyurethane latex, acrylic ester emulsion, vinyl acetate emulsion, ethylene / vinyl acetate emulsion, vinyl chloride latex, Polystyrene latex, polyethylene emulsion, silicone emulsion, polybutene emulsion, thiocol latex, epoxy emulsion,
And so on. Further, a polymer emulsion obtained by emulsion polymerization using a polymer compound such as AA-PVA or PVA as an emulsifier is also included.

The aqueous solution and the aqueous emulsion of such a polymer compound may be used alone or in combination of two or more kinds, and when the water-soluble polymer and the emulsion are used in combination, the mixing weight ratio of both is 5%. / 95 to 95/5 is suitable.
These usually have a solid content of 10 to 70% by weight.
Such A component may include a plasticizer, a colorant, a filler, which is usually used as needed, and an aldehyde, an isocyanate compound, an epoxy compound, zirconium, which has a relatively slow curing rate for the purpose of permanent adhesion strengthening. A crosslinking agent composed of a polyvalent metal salt of chromium, aluminum, iron, copper or the like may be added in an appropriate amount at the time of preparing the component A or immediately before coating.

The curing agent in the component B of the present invention is not particularly limited, and examples include formaldehyde, acetaldehyde,
Aldehyde compounds consisting of monoaldehydes such as benzaldehyde, dialdehydes such as glyoxal, malondialdehyde and dialdehyde starch, hydrazine, hydrazine hydrate, inorganic and organic salts of hydrazine, carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide. , A hydrazine compound consisting of succinic acid dihydrazide, adipic acid dihydrazide, etc.,
Examples include urea, melamine and their methylol compounds, amine-based compounds such as hexamethylenediamine and triethanolamine, imine-based compounds such as polyethyleneimine, and polyamidoamine resins, which correspond to the component A in actual use. The thing is selected appropriately.

The fine particles which do not directly react with the curing agent in the present invention have a large surface area and are preferably porous, and are preferably insoluble or swellable in water at 60 ° C. or lower. For example, corn starch and potatoes. Starch, sweet potato starch, wheat starch, kissava starch, sago starch, tapioca starch, sorghum starch, rice starch, bean starch, kudzu starch, bracken starch, lotus starch, hissi starch, flour, and various starch powders, partially crosslinked polyacrylic acid ,
Water absorbent resin powders such as PVA and its derivatives and partially crosslinked products thereof, casein, blood meal, soybean protein, calcium carbonate,
Talc, calcium silicate, clay, gypsum, shirasu, silica, bentonite, titanium oxide, magnesium oxide, zeolite, magnesium aluminum silicate, satin white, barium sulfate, extender pigments such as zinc white, and colored pigments. One kind or a mixture of two or more kinds is used.

The particle size of the fine powder is not particularly limited, but preferably the particle size is 500 μm to 0.5 μm. If it exceeds 500 μm, the adhesive main agent cannot be uniformly hardened, and the adhesion is further reduced. Since the adhesiveness of the agent also deteriorates, the adhesive strength also decreases. On the other hand, when the thickness is 0.5 μm or less, the localized thick coating of the adhesive main agent is insufficiently cured, and the purpose cannot be met. The mixing method of the curing agent and the fine powder is not particularly limited, and the curing agent is directly mixed with the fine powder, or either the curing agent or the fine powder is dissolved or dispersed in water and water / organic solvent. The mixture is stirred and mixed by the above method to form a slurry.
Such an aqueous slurry may be left as it is, or may be dried by heating with stirring to give a powder.

A suitable mixing ratio of the curing agent and the fine powder is a curing agent / fine powder = 1/100 to 100/1, preferably 20/80 to 80/20. In the case of an aqueous slurry, a solid content of about 10 to 70% by weight is usually suitable. If necessary, a spreading binder that does not directly react with the curing agent can be added to the component B. Examples of the spreading agent include PVA and its derivatives, polyvinylpyrrolidone, polyoxyethylene, and ethylene oxide. Propylene oxide copolymer, acrylic acid copolymer,
Synthetic polymer aqueous solution such as polycarboxylic acid type copolymer and /
Or emulsion, organic solvent paste, alginic acid or a salt thereof, guar gum, locust bean gum, carboxymethyl cellulose sodium salt, methyl cellulose,
Cellulose derivatives such as hydroxypropyl cellulose and hydroxyethyl cellulose, natural polymer aqueous solutions such as lignin sulfonate, gelatin and carrageenan may be mixed in appropriate amounts, and tackifiers such as tacky fire, various adhesives, colorants, and interfaces. An activator, a viscosity modifier, etc. may be appropriately mixed.

The fast-curing water-based adhesive comprising the components A and B obtained according to the present invention is applied to the adhered surface on which the component A is to be adhered, for example, one surface of wood or the like, and the component B is not adhered. And apply to other adherends. A
The coating amount of the components is 50 to 300 in terms of solid content.
It is evenly applied to the surface of the base material so as to be about g / m ² . B
Any method may be used as a method for applying the components, for example, a method in which a necessary spreading agent is applied to the adherend surface in advance, and a mixture of the fine powder and the curing agent is spread thereon, and such a mixture is used. Examples thereof include a method of applying as an aqueous slurry or a method of applying and drying the aqueous slurry in advance, or a method of applying in a powder state as it is by a usual coating machine such as a brush, a spray roll coater and a flow coater. The coating amount on the substrate is preferably about 5 to 300 g / m ² in terms of solid content.

When both surfaces of the base material coated with the component A and the component B are closely adhered, pressed and pressed, a considerable initial adhesive strength is obtained within 15 seconds to 30 minutes at room temperature, and in such a short time. It can be decompressed, and when left alone for curing, its final bond strength is sufficiently high. In addition, it is possible to perform machining such as cutting shortly after releasing the pressure. In general, an adhesive used as an aqueous medium does not have a sufficient final adhesive strength at room temperature unless it is pressed / pressed for a considerably long time. However, according to the adhesive composition of the present invention, a rapid curing property is obtained. Therefore, even if the compression / pressing is performed for a short time, it is possible to perform the bonding with a sufficient final bonding strength after leaving and curing.

The adhesive composition of the present invention comprises various wood materials such as wood, wood materials such as chipboards and hardboards, inorganic materials such as slate boards and silica boards, melamine resin decorative boards, pakelite boards, foams. It is possible to bond plastic materials such as polystyrene, corrugated paper, paperboard, kraft paper and other paper materials. Therefore, it is used for the plane bonding of flash panels, decorative plywood, prefabricated panels, laminated wood, etc., for wire bonding, hozo, dowels, tomes, nails, shavings, other wood industries such as assembly and furniture assembly, and also for corrugated board, plywood, It can be used for paper processing such as paper tubes, paper containers, and bag making. Its work is quick and labor-saving, and it can bond even at room temperature, contributing to shortening of bonding work time and energy saving.

[0018]

[Working] The fast-curing water-based adhesive of the present invention exhibits sufficient adhesive strength by pressing for an extremely short time, and also adheres due to the porosity of the adherend, the water content and some unevenness. It has little effect on the strength, and the main agent and the curing agent are in an ideal mixed state, so that the excellent properties inherently possessed can be sufficiently exhibited, and high adhesive strength is obtained, so that the usefulness thereof is extremely high.

[0019]

The present invention will be described in detail below with reference to examples. The terms "part" and "%" are based on weight unless otherwise specified. (Example 1) A component AA PVA (polymerization degree 1300, saponification degree 97 mol%,
MDI to 100 parts of vinyl acetate resin emulsion with acetoacetylation degree of 5.5 mol% as protective colloid
15 parts of a system isocyanate (Sumijour 44V-20, manufactured by Sumitomo Bayer Urethane Co., Ltd.) was stirred and mixed immediately before coating. However, the vinyl acetate emulsion was obtained as follows. A glass polymerization container was charged with 147 parts of water, 17 parts of the above-mentioned protective colloid and 0.12 part of anhydrous sodium acetate, and the internal temperature was raised to 85 ° C. to dissolve the protective colloid.
Next, 120 parts of vinyl acetate and 10 parts of a 3% aqueous solution of potassium persulfate were separately added dropwise at 70 ° C. over 3 hours, and 10 parts of a 6% aqueous solution of sodium bisulfite was added immediately before the end of the addition of vinyl acetate. After aging for 1 hour to complete emulsion polymerization, the emulsion obtained by cooling was 45% in solid content and 150 poises in viscosity.

Component B: A 1-liter tabletop kneader was charged with 300 parts of calcium carbonate having an average particle size of 40 μ (manufactured by Shiraishi Calcium Co.), and a 70% hydrazine carbonate solution (Japan Hydrazine Industry Co., Ltd.
(Products Co., Ltd.) 72 parts by stirring and mixing to uniformly impregnate, and then a suspension polymerized product of sodium polyacrylate which is a highly water-absorbent resin (average particle diameter 130 μ, AQUAR Reserve AP-10
0, 200 parts by Nippon Synthetic Chemical Industry Co., Ltd.) were mixed to obtain a powder containing 10% of a curing agent. The compression shear adhesive strength of the quick-curing water-based adhesive composed of the components A and B was measured by the method described below. The results are summarized in Table 1.

Compressive shear adhesive strength (according to JIS K-6852) (A) For two pieces of 25 mm × 50 mm × 10 mm birch, one component is coated with the component A at a coating amount of 220 g / m ^2. After being coated, the component B was uniformly sprayed on the other side through a 60-mesh wire net so as to have a content of 50 g / m ² , and immediately the both sides coated were brought into contact with each other and pressed at 5 kgf / cm ² . (B) A test piece was prepared in the same manner as described above except that the component A was a haematsuga material and the component B was a lauan plywood. (C) A test piece was prepared in the same manner as described above except that the component A was changed to a hemlock material and the component B was changed to a gypsum board (containing fibers). However, the measurement was a normal state and water resistance test except for hot water resistance treatment.

Then, each of (A), (B) and (C) was decompressed after each pressing time shown in Table 1 and the compressive shear bond strength was measured after curing for 5 minutes and after curing for 72 hours. (Water resistance) After the above curing, the adhesive test piece was immersed in room temperature water at about 25 ° C. for 6 hours, and then the compressive shear strength was immediately measured. However, the test piece (C) was immersed in room temperature water for 6 hours, dried at room temperature for 20 hours, and then the compressive shear strength was measured. (Heat-resistant water) After curing as described above, the adhesive test piece was immersed in warm water of about 60 ° C. for 3 hours and then cooled to room temperature water, and the compressive shear strength was immediately measured. (Comparative Example 1) Except that calcium carbonate and polyacrylic acid powder were not used as the component B in Example 1, a 5% aqueous solution of hydrazine carbonate was applied at 50 g / m ² and dried at room temperature for 4 hours. An experiment was conducted according to the same example.
The results are summarized in Table 1.

[0023]

[Table 1] Table 1

Note 1) The adherend (A) is a birch / birch, (B) is a hemlock / lauan, and (C) is a hemlock / gypsum. Note 2) The adhesive strength is test piece 7 The average value of each piece is shown. * 3) The material breakage rate is shown in parentheses after 72 hours of curing.

From Table 1 above, the adhesive composition of the present invention comprising the components A and B is excellent in adhesion not only to hard and fine birch but also to soft and porous lauan wood and gypsum wood with high water absorption. You can see that it shows power.

(Example 2) Component A AA PVA (polymerization degree 1700, saponification degree 88 mol%,
30% 20% aqueous solution with acetoacetylation degree of 5.7 mol%)
Parts, 1 part of a 20% aqueous solution of sodium bisulfite, styrene-butadiene copolymer latex (DL-612, manufactured by Asahi Chemical Industry Co., Ltd., resin content 48%, viscosity 1400 cps).
To 100 parts of an aqueous dispersion (solid content 50%) consisting of 48 parts and 21 parts of calcium carbonate, diphenylmethane diisocyanate (Millionate MR, Nippon Polyurethane Co., Ltd.)
10 parts (manufactured by the company) were mixed by stirring immediately before coating.

Ingredient B: 300 parts of bentonite (average particle size: 74μ, manufactured by Hanai Chemical Co., Ltd.) was charged in a tabletop kneader having a content of 1 liter to prepare a polyamide amine resin (Tomeide # 2500, manufactured by Fuji Kasei Co., Ltd.). After mixing and impregnating 100 parts of a 30% methanol solution, it was heated with stirring to obtain a powder. One of the adherends was brushed with this powder. The compression shear adhesive strength of the quick-setting water-based adhesive composed of the components A and B was measured according to Example 1. However, the coating conditions of the quick-curing water-based adhesive are as follows. The results are summarized in Table 2.

For each of (A) two pieces of 25 mm × 50 mm × 10 mm birch, and (B) two pieces of 25 mm × 50 mm × 12 mm lauan plywood, one component is coated with the component A in an amount of about 100 g.
/ M ² (solid content) and component B on the other side to a coating amount of about 5 to 10 g / m ² (curing agent content), then both components A and B are applied. Was immediately contacted and immediately clamped at 5 kgf / cm ² .

Example 3 Component A AA PVA (polymerization degree 1700, saponification degree 88 mol%,
16.2% aqueous solution with acetoacetylation degree of 6.2 mol% 3
7 parts, ethylene-vinyl acetate copolymer emulsion (ethylene: vinyl acetate = 41: 59 (weight ratio), resin content 5
5%, viscosity 2100 cps) 42 parts and calcium carbonate 2
Diphenylmethane diisocyanate (Millionate M) per 100 parts of an aqueous dispersion (solid content 50%) consisting of 1 part
R, manufactured by Nippon Polyurethane Co., Ltd.) was mixed with stirring just before coating.

Component B 30 parts of a 10% aqueous solution of adipic dihydrazide, partially saponified PVA (GL-05, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 5
% Aqueous solution 10 parts, corn starch (average particle size 20 μ) 6
A 60% slurry liquid consisting of 0 parts was previously applied and dried on the adhesive substrate. Using the components A and B shown above,
Compressive shear adhesion was measured according to Example 2. The results are summarized in Table 2.

(Example 4) Component A: 100 parts of a 30% aqueous solution of partially imidized isoban (Isoban 304, manufactured by Kuraray Co., Ltd.), a styrene acrylic copolymer emulsion (Polytron T-810, Asahi Kasei Kogyo).
Co., Ltd., resin content 50%, viscosity 2500 cps) 80 parts and calcium carbonate 20 parts with sufficient stirring and mixing 45% aqueous dispersion B component Glyoxal 40% aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 50 Part, and a 67% slurry liquid consisting of 100 parts of Kaolin clay (manufactured by Burgess Pigment Co.), and the compression shear adhesive strength was measured according to Example 2 using the components A and B shown above. The results are summarized in Table 2.

Comparative Example 2 An experiment was carried out in the same manner as in Example 2, except that bentonite was not used as the component B and a 30% solution of polyamidoamine resin in water: methanol = 1: 1 was applied. The results are summarized in Table 3. (Comparative Example 3) An experiment was carried out in the same manner as in Example 3 except that the starch B and the partially saponified PVA were not mixed as the component B. The results are summarized in Table 3. (Comparative Example 4) An experiment was conducted according to the same example as Example 4, except that kaolin clay was not mixed as the B component. The results are summarized in Table 3.

[0033]

[Table 2] Table 2

Note 1) (A) indicates birch / birch material, (B) indicates lauan / lauan material Note 2) () in component B indicates hardener content Note 3) Adhesive strength is tested Shown as the average value of 7 pieces Note 4) () shows the material breakage rate after 72 hours of curing.

[0035]

[Table 3] Table 3

Note 1) (A) indicates birch / birch material, (B) indicates lauan / lauan material Note 2) () in component B indicates curing agent content Note 3) Adhesive strength is tested Shown as the average value of 7 pieces Note 4) () shows the material breakage rate after 72 hours of curing.

[0037]

In general, the water-based adhesive requires pressing for a considerably long time, but the fast-curing water-based adhesive of the present invention has an ideal mixed state of the main agent and the curing agent. The adhesive strength is not affected, the original excellent properties can be fully exhibited, and a high degree of adhesive strength can be obtained, which is industrially very advantageous.

Claims (3)

[Claims] 1. A fast curing comprising (A) component A consisting of an aqueous solution and / or aqueous emulsion of a polymer compound (B) a curing agent and B component comprising a mixture containing fine particles that do not directly react with the curing agent. Water-based adhesive 2. A fast-curing water-based adhesive in which the fine particles of the component B in claim 1 have a particle size of 500 μm to 0.5 μm. 3. A bonding method, characterized in that the components A and B according to claim 1 are separately applied to the surface of an adherend, and then the coated surfaces are closely adhered to each other.