JPH10279912A - Aqueous adhesive compostion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in initial adhesivity, water- resistant adhesivity, etc., and suitable for adhesion of plastic foam, by including an aqueous dispersion of a specific polyurethane resin and a water-dispersible polyisocyanate compound. SOLUTION: This composition is obtained by compounding (A) an aqueous dispersion of a polyurethane resin having terminal hydrazine groups and a hydrazine equivalent of 500-15000, obtained by neutralization, with a base, of a reaction product of a carboxyl group-containing prepolymer having terminal isocyanate groups, obtained from (i) an organic isocyanate, (ii) a high molecular polyol, (iii) an α,α-dimethylol monocarboxylic acid, and as necessary and (iv) a low molecular active hydrogen compound, with (v) hydrazine (derivative) in an excess equivalent compared to the above terminal hydrazine groups, with (B) a water-dispersible polyisocyanate compound obtained e.g. by compounding a polyisocyanate compound with a surfactant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an aqueous adhesive composition. More specifically, the present invention relates to a water-based adhesive suitable for bonding plastic foam (polyurethane foam, foamed polyolefin, foamed polyvinyl chloride, and the like) requiring initial adhesion, water resistance, and oil resistance.

[0002]

2. Description of the Related Art Conventionally, solvent-based polyurethane resin adhesives have been widely used as adhesives for plastic foams. As a water-dispersible polyurethane resin adhesive, a blocked isocyanate-based adhesive using a blocking agent such as methyl ethyl ketone oxime or acetoacetone which regenerates an isocyanate group by heat treatment (for example, Japanese Patent Publication No. 2-32294) is proposed. Have been.

[0003]

However, since the former uses an organic solvent, it has problems in terms of low pollution, resource saving, and safety and health. In the latter, the block is dissociated and the isocyanate is used. Since the temperature for regenerating the group is high, there is a problem that it can be used only for a limited substrate.

[0004]

DISCLOSURE OF THE INVENTION In view of the above problems, the present inventors have conducted intensive studies to obtain an adhesive having both initial adhesiveness, water-resistant adhesiveness and oil-resistant adhesiveness, and have reached the present invention. . That is, the present invention comprises an aqueous dispersion of a polyurethane resin (A) and a water-dispersible polyisocyanate compound (B), wherein (A) is an organic isocyanate (a), a polymer polyol (b), α, α- Reaction of a carboxyl group-containing isocyanate group-terminated prepolymer from dimethylol monocarboxylic acid (c) and, if necessary, a low molecular weight active hydrogen compound (d) with an excess of hydrazine or its derivative (f) relative to the isocyanate group of things, consist neutralized product with a base (e), has a molecular terminal hydrazine groups (-HNNH _2), and a plastic foam water based adhesive composition, characterized in that hydrazine group equivalent weight of 500 to 15,000 Things.

The organic polyisocyanate (a) constituting (A) in the present invention includes, for example, aliphatic polyisocyanates having 2 to 12 carbon atoms (excluding carbon in the isocyanate group) [ethylene diisocyanate, tetramethylene diisocyanate, Hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate,
2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 1,3,6-hexamethylene triisocyanate, etc.]; an alicyclic polyisocyanate having 4 to 15 carbon atoms (excluding carbon in the isocyanate group) [isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4 ′ diisocyanate (hydrogenated MDI), 1,4-cyclohexane diisocyanate, methylcyclohexane-2,4-diisocyanate, 1,4-bis (2-isocyanatoethyl) cyclohexane, etc.]; Aromatic polyisocyanate having 8 to 12 carbon atoms (excluding carbon in isocyanate group) [xylylene diisocyanate, tetramethyl xylylene diisocyanate (TMXDI), etc.]; carbon number (excluding carbon in isocyanate group) ) 6 or more aromatic polyisocyanates [1,4-phenylene diisocyanate, 2,4
-Or 2,6-toluene diisocyanate (TD
I), diphenylmethane-2,4'- or 4,4'-
Diisocyanate (MDI), naphthalene-1,5-diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, o-tolidine diisocyanate, crude TDI, polyphenylmethane polyisocyanate (crude MDI), etc .; And mixtures of two or more of the above. Among these, preferred are TDI, MDI, HDI, IPDI, hydrogenated MDI and TMXDI, and particularly preferred are TDI and MDX.
DI.

As the high molecular polyol (b), polyether polyol ｛low molecular polyol [polyhydric alcohols (ethylene glycol, propylene glycol, 1,
Bifunctional polyols such as 3- or 1,4-butanediol, neopentylglycol, diethylene glycol; trifunctional or higher functional polyols such as glycerin, trimethylolpropane, sorbitol), polyhydric phenols (bisphenols such as bisphenol A)] and Amines (alkanolamines such as monoethanolamine, diethanolamine, triethanolamine;
Aliphatic amines such as monobutylamine, ethylenediamine, hexamethylenediamine, diethylenetriamine; alicyclic amines such as isophoronediamine, 1,4
-Diaminocyclohexane; one or more of alkylene oxides having 2 to 4 carbon atoms (such as ethylene oxide, propylene oxide, and butylene oxide) of aromatic amines such as tolylenediamine and 4,4'-diaminodiphenylmethane. (Random and / or block)] adducts, ring-opening polymers of alkylene oxides (such as polytetramethylene ether glycol), etc .; polyester polyols; polycarboxylic acids [aliphatic polycarboxylic acids (eg, adipic acid, succinic acid, fumaric acid) Acid, sebacic acid, maleic acid and dimerized linoleic acid) and / or aromatic polycarboxylic acids (for example, phthalic acid, isophthalic acid and terephthalic acid)] and low molecular polyols (the polyhydric alcohols) or A polyester polyol having a hydroxyl group at the end obtained by a polycondensation reaction with an ether polyol (eg, polyethylene glycol, polypropylene glycol), a polylactone polyol (eg, polycaprolactone diol), a polycarbonate diol, etc .; and a mixture of two or more of these. No.
Preferred among these are polyester polyols. OH equivalent (molecular weight per hydroxyl group) of (b)
Is usually 150 to 3000, preferably 200 to 2500
It is.

Α, α-Dimethylol monocarboxylic acid (c) is a component used for introducing an anionic hydrophilic group for stably dispersing the polyurethane resin (A) in water. Include α, α-dimethylolacetic acid, α, α-dimethylolpropionic acid and α, α-dimethylolpropionic acid.
α-dimethylol butyric acid is preferred, and α, dimethylol butyric acid is preferred.
α-Dimethylolpropionic acid. The amount of (c) in (A) is such that the carboxyl group (-COOH)
The amount is usually 0.3 to 6% by weight, preferably 0.4 to 5% by weight, based on the solid content of (A). If the amount of carboxyl groups is less than 0.3% by weight, a stable dispersion cannot be obtained.
If the amount is more than 10% by weight, the water resistance decreases.

The low-molecular-weight active hydrogen compound (d) optionally used includes low-molecular-weight polyols and polyamines. Examples of the low molecular polyol include bifunctional or trifunctional low molecular polyols among the polyhydric alcohols exemplified as the raw materials for the polyether polyol. Examples of the polyamine include diamines among the amines mentioned as the raw material of the polyether polyol. Preferred among these are low molecular polyols.

The base (e) for neutralizing a carboxyl group in the polyurethane resin includes an organic base (eg, trimethylamine, triethylamine, etc.) and an inorganic base (eg, sodium hydroxide, potassium hydroxide, ammonia, etc.). Preferred among these are organic bases. The amount of (e) is the amount of carboxyl group 1 in (A).
It is usually 0.3 to 1 mole per mole.

The hydrazine or hydrazine derivative (f) includes, for example, hydrazine, dibasic dihydrazide (eg, adipic dihydrazide, sebacic dihydrazide, isophthalic dihydrazide, etc.), carbodihydrazide, iminodiacetic acid dihydrazide, and preferred is hydrazine. , Adipic dihydrazide and carbodihydrazide.

The production method of (A) is not particularly limited,
For example, an organic polyisocyanate (a) and an active hydrogen group-containing organic solvent in the presence or absence of an organic solvent containing no active hydrogen group in the molecule (eg, acetone, dioxane, tetrahydrofuran, N-methylpyrrolidone toluene, ethyl acetate, etc.) The compound components [(b), (c) and, if necessary, (d)] are combined with an isocyanate (hereinafter abbreviated as NCO) group and an active hydrogen group other than a carboxyl group in an equivalent ratio of usually (1.05 to 2). : 1, preferably (1.05 to
The reaction is usually carried out at 20 to 150 ° C, preferably 60 to 120 ° C by a one-shot method or a multi-step method in the range of 1.5) to obtain a carboxyl group-containing terminal NCO prepolymer. The NCO group content in the prepolymer is usually 0.1.
5 to 5% by weight.

Subsequently, hydrazine or a derivative (f) thereof is reacted. The reaction is carried out before, simultaneously with, or after neutralizing the prepolymer with a base (e). A method of reacting an excess equivalent of (f) with respect to the hydrazine group at the molecular end and then emulsifying by adding water; or neutralizing the prepolymer with (e), Reaction and emulsification may be performed while adding an aqueous solution. The amount of (f) is usually 1.1 to 2 per equivalent of NCO group in the prepolymer.
Is equivalent. If necessary, the organic solvent may be removed from the obtained emulsion.

In the present invention, it is necessary that (A) contains a hydrazine group (—NHNH 2) at the molecular terminal, and by containing this group, the water-dispersible polyisocyanate compound (B) Cross-linking reaction is possible. The amount of the hydrazine group in (A) is such that the hydrazine group equivalent (molecular weight per hydrazine group) of (A) is usually 500 to 15000, preferably 1000 to 1500.
It is an amount that becomes zero. If the hydrazine group equivalent is less than 500, the adhesive becomes brittle and the adhesive strength is reduced. If it exceeds 15,000, the initial adhesiveness is undesirably reduced. The hydrazine group equivalent is determined by the following equation. Hydrazine group equivalent = (resin amount of NCO-terminated prepolymer + weight of hydrazine derivative) ÷ (− of hydrazine derivative
Equivalent number of NHNH ₂ groups-NC of NCO-terminated prepolymer
O group equivalent)

The water-dispersible polyisocyanate compound (B), which is another essential component in the present invention, includes, for example, a polyisocyanate compound and a surfactant (for example, JP-A-63-317515 and JP-A-64-317515).
114, and a polyisocyanate compound having a molecule in which a hydrophilic group such as a polyoxyethylene chain is introduced (for example, compounds described in Japanese Patent Publication Nos. 1-48263 and 2-58287). ), Any of which can be dispersed in water can be used. Specific examples include "Aquanate 110" (manufactured by Nippon Polyurethane Industry), "Takenate NW-4 (2)" (manufactured by Takeda Pharmaceutical) and "Cosmonate M-200W" (manufactured by Mitsui Toatsu Chemicals).

The solid content weight ratio of (A) to (B) in the present invention is usually (99: 1) to (50:50), preferably (97: 3) to (70:30). When the ratio of (B) is less than 1, sufficient water- and oil-resistant adhesiveness cannot be obtained, and when it exceeds 50, the adhesive becomes brittle and the adhesive strength decreases, which is not preferable.

The method of mixing (A) and (B) is not particularly limited. For example, (A) and (B) may be mixed by a paddle type stirring system or other mixing devices (kneader, impeller disperser,
Using a stone mill).

The plastic foam to be adhered to the adhesive of the present invention includes polyurethane foam, foamed polyvinyl chloride, foamed polyethylene, foamed polypropylene,
Expanded polystyrene and the like can be mentioned.

[0018] The aqueous adhesive composition of the present invention may optionally contain other aqueous resins, inorganic fillers, stabilizers, dispersants, surfactants, thickeners, preservatives, antifreezing agents and the like. Agents can be added. Specific examples of these are as follows. Aqueous resin: Acrylic, vinyl acetate, vinyl chloride or urethane resin aqueous dispersion, SBR or NBR
Latex, etc. Inorganic fillers: calcium carbonate, silica, talc, etc. Stabilizers: hindered phenol-based, phosphorus-based, benzophenone-based, benzotriazole-based, oxalic acid anilide-based and hindered amine-based stabilizers. Dispersant: polyacrylic acid (salt) and the like. Surfactants: Nonionic surfactants such as ethylene oxide adduct of nonylphenol. Thickeners: polyacrylic acid (salt), cellulose derivatives, starch derivatives, polyvinyl alcohol, and the like. Preservatives: organic nitrogen sulfur compound-based or organic sulfur halogen compound-based preservatives. Antifreeze: ethylene glycol, propylene glycol, and the like.

The method for applying the aqueous adhesive composition of the present invention to an adherend includes brush coating, roll coating, spray coating, flow coating and dipping. After drying the applied adhesive, it is bonded to the other adherend (dry bonding) and cured at room temperature, the crosslinking proceeds and the adhesive layer hardens. If necessary, the composition can be heated to about 60 to 80 ° C. to accelerate the curing. Furthermore, the applied adhesive can be bonded to another adherend without being dried (wet adhesion) and cured.

The aqueous adhesive composition of the present invention is particularly suitable for use as an adhesive for plastic foams, since it has excellent initial adhesion, water resistance and oil resistance. It can also be used as an adhesive for plastic molded products, wood, fibers, metals and the like.

[0021]

EXAMPLES The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. In the following, “part” indicates “part by weight” and “%” indicates “% by weight”.

Production Example 1 Polybutylene adipate diol (number average molecular weight 2000) 19 was placed in a closed reaction vessel equipped with a thermometer and a stirrer.
After charging 5.8 parts, 0.6 parts of 1,4-butanediol, 8.9 parts of dimethylolpropionic acid, 44.7 parts of TDI and 250.0 parts of tetrahydrofuran, the reaction system was replaced with nitrogen gas and then stirred. Reaction at 80 ° C. for 9 hours
An NCO-terminated urethane prepolymer having a CO% content of 1.1% was obtained. The obtained tetrahydrofuran solution was cooled to 30 ° C., and 6.7 parts of triethylamine was added. Next 8
8.1 parts of a 0% hydrazine hydrate aqueous solution was added to 381.
0 parts, added to the tetrahydrofuran solution, added with a hydrazine block, and emulsified. Thereafter, tetrahydrofuran was distilled off under reduced pressure at 50 to 60 ° C. to obtain a solid content of 40% and a viscosity of 330%.
635 parts (A1) of an aqueous dispersion of a polyurethane resin having a hydrazine residue equivalent of 1982 at cP / 25 ° C. was obtained.

Production Example 2 Polycaprolactone diol (number average molecular weight 2020) 176.3 was placed in a closed reaction vessel equipped with a thermometer and a stirrer.
, 4.5 parts of 1,4-butanediol, 6.7 parts of dimethylolpropionic acid, 62.5 parts of IPDI, and 250.0 parts of acetone, and the reaction system was purged with nitrogen gas. The reaction was carried out for 9 hours to obtain an NCO-terminated urethane prepolymer having an NCO% content of 1.2%. 24. Adipic dihydrazide is added to the resulting acetone solution.
8 parts were added and reacted at 80 ° C. for 5 hours to obtain an adipic dihydrazide block in which NCO was completely reacted. The obtained block was cooled to 30 ° C., and 5.1 parts of triethylamine was added. Next, 412.2 parts of water was added for emulsification, and acetone was distilled off under reduced pressure at 50 to 60 ° C., and an aqueous dispersion 687 of a polyurethane resin having a solid content of 40%, a viscosity of 366 cP / 25 ° C., and a hydrazine residue equivalent of 1934 was obtained. Part (A
2) was obtained.

Production Example 3 3-Methyllentan adipate diol (number average molecular weight 985) 1 was placed in a closed reaction vessel equipped with a thermometer and a stirrer.
54.3 parts, dimethylolpropionic acid 18.6 parts, T
After 77.1 parts of DI and 250.0 parts of dioxane were charged and the reaction system was replaced with nitrogen gas, the mixture was reacted at 80 ° C. for 8 hours with stirring to obtain an NCO-terminated urethane prepolymer having an NCO% content of 2.1%. . The obtained dioxane solution was cooled to 30 ° C., and triethylamine (14.0 parts) and 80%
Add 15.6 parts of hydrazine hydrate aqueous solution to neutralize,
Hydrazine blocked. Next, 387.0 parts of water was added to the dioxane solution to emulsify the solution, and then 50 to 60 under reduced pressure.
Dioxane was distilled off at 40 ° C., solid content 40%, viscosity 390 c
645 parts (A3) of an aqueous dispersion of a polyurethane resin having a P / 25 ° C. and a hydrazine residue equivalent of 1035 was obtained.

Production Example 4 In a closed reaction vessel equipped with a thermometer and a stirrer, 3-methylpentane adipate diol (number average molecular weight 2975)
203.6 parts, dimethylolpropionic acid 8.9 parts, H
After 37.5 parts of DI and 250.0 parts of dioxane were charged and the reaction system was replaced with nitrogen gas, the mixture was reacted at 80 ° C. for 9 hours with stirring to obtain an NCO-terminated urethane prepolymer having an NCO% content of 1.0%. . 12.1 parts of adipic dihydrazide were added to the obtained dioxane solution,
After reacting for an hour, NCO was completely reacted to obtain an adipic dihydrazide block. 30 blocks obtained
After cooling to ℃, 6.7 parts of triethylamine was added. Next, after adding 393.0 parts of water and emulsifying, 50 to 6 under reduced pressure.
Dioxane is distilled off at 0 ° C., solid content 40%, viscosity 120
655 parts (A4) of an aqueous dispersion of a polyurethane resin having a hydrazine residue equivalent of 13105 at 6 cP / 25 ° C. was obtained.

Production Example 5 3-Methylpentane adipate diol (number average molecular weight 2975) was placed in a closed reaction vessel equipped with a thermometer and a stirrer.
203.6 parts, dimethylolpropionic acid 8.9 parts, H
After 37.5 parts of DI and 250.0 parts of dioxane were charged and the reaction system was replaced with nitrogen gas, the mixture was reacted at 80 ° C. for 9 hours with stirring to obtain an NCO-terminated urethane prepolymer having an NCO% content of 1.0%. . 11.6 parts of adipic dihydrazide were added to the obtained dioxane solution,
After reacting for an hour, NCO was completely reacted to obtain an adipic dihydrazide block. 30 blocks obtained
After cooling to ℃, 6.7 parts of triethylamine was added. Next, after 392.0 parts of water was added and emulsified, 50 to 6
Dioxane is distilled off at 0 ° C., solid content 40%, viscosity 154
654 parts (A5) of an aqueous dispersion of a polyurethane resin having a hydrazine residue equivalent of 18167 at 5 cP / 25 ° C. was obtained.

Production Example 6 Polycaprolactone diol (number average molecular weight 1950) 194.7 was placed in a closed reaction vessel equipped with a thermometer and a stirrer.
Part, 8.9 parts of dimethylolpropionic acid, TDI46.
After 4 parts and 250.0 parts of acetone were charged and the reaction system was replaced with nitrogen gas, the mixture was reacted at 80 ° C. for 8 hours with stirring to obtain an NCO-terminated urethane prepolymer having an NCO% content of 1.2%. The obtained acetone solution was cooled to 30 ° C., and 6.7 parts of triethylamine was added. Then water 375.
0 parts were added to the acetone solution to elongate and emulsify with water, and then acetone was distilled off under reduced pressure at 50 to 60 ° C. to obtain a polyurethane resin aqueous dispersion 6 having a solid content of 40% and a viscosity of 585 cp / 25 ° C.
25 parts (A6) were obtained.

Examples 1 to 4 The dispersions (A1) to (A4) of the polyurethane resin and the water-dispersible polyisocyanate compound (B1) or (B2) obtained in Production Examples 1 to 4 are shown in Table 1. The adhesive composition was blended at each mixing ratio to obtain the adhesive composition of the present invention. These were tested for initial adhesion, water resistance and oil resistance according to the following performance test methods. Table 3 shows the results.
Shown in The water-dispersible polyisocyanate compound (B
1) and (B2) are as described below. B1: "Aquanate 110" (manufactured by Nippon Polyurethane Industry) B2: "Takenate NW-4 (2)" (manufactured by Takeda Pharmaceutical)

[0029]

[Table 1]

Comparative Example 1 or 2 The polyurethane resin dispersion (A5) or (A6) obtained in Production Examples 5 and 6 and the water-dispersible polyisocyanate compound (B1) were mixed in the proportions shown in Table 2 respectively. And a comparative adhesive composition was obtained. These were tested for initial adhesion, water resistance and oil resistance according to the following performance test methods. Table 3 shows the results.

[0031]

[Table 2]

[0032]

[Table 3]

[Performance test method] Initial adhesion: A thickener (“SN Thickener A-803” manufactured by San Nopco) was prepared by mixing the compounds of Examples 1 to 4 and Comparative Examples 1 and 2 so that the viscosity became 4000 to 5000 cP. ) And adjust with a soft urethane slab foam (100 mm x 120
mm, thickness 5 mm, bulk specific gravity 0.05)
g / m ² . After drying at 80 ° C. for 2 minutes, another soft urethane slab foam (100 mm × 120 mm, thickness 5 mm, bulk specific gravity 0.05) to which no adhesive is applied is pressure-bonded with a load of 4 kg for 10 seconds and immediately cut into 25 mm width. The peel strength of the test piece thus measured was measured with an autograph (crosshead speed 500 mm / min.). A peel strength of 200 g or more with a width of 25 mm was regarded as good initial adhesion. Water resistance: A test piece prepared in the same manner as the initial adhesion was cured at room temperature for 24 hours. Thereafter, the peel strength was measured immediately after immersion in boiling water for 1 hour. The material which was broken by the soft urethane slab foam of the adherend was evaluated as good. Oil resistance: A test piece prepared in the same manner as the initial adhesion was cured at room temperature for 24 hours, and immediately after immersion in light oil for 6 hours, the peel strength was measured. The material which was broken by the soft urethane slab foam of the adherend was evaluated as good.

[0034]

The aqueous adhesive composition of the present invention has the following effects which cannot be achieved by the prior art. (1) It has both excellent initial adhesion, water resistance and oil resistance. (2) Sufficient initial adhesiveness can be obtained even when the coated surface is dried and bonded. (3) It has good water resistance and oil resistance at room temperature. Because of the above effects, the aqueous adhesive composition of the present invention,
Particularly, it is extremely useful as an adhesive for a plastic foam which requires initial adhesion, water resistance and oil resistance.

Claims (4)

[Claims] 1. An aqueous dispersion of a polyurethane resin (A) and a water-dispersible polyisocyanate compound (B),
(A) is a carboxyl group-containing isocyanate group terminal from an organic isocyanate (a), a polymer polyol (b), an α, α-dimethylol monocarboxylic acid (c) and, if necessary, a low molecular weight active hydrogen compound (d). Base (e) of a reaction product of a prepolymer and hydrazine or a derivative (f) thereof in an excess equivalent to the isocyanate group;
And a hydrazine group (-H
NNH ₂₎ has, and hydrazine group equivalent 500 to 1
A water-based adhesive composition for plastic foam, which is 5000. 2. The aqueous adhesive composition according to claim 1, wherein (f) is at least one selected from hydrazine, dibasic dihydrazide and carbodihydrazide. 3. The aqueous adhesive composition according to claim 1, wherein (B) is a mixture of a polyisocyanate compound and a surfactant, and / or a polyisocyanate compound having a hydrophilic group introduced into a molecule. Stuff 4. The solid content weight ratio of (A) and (B) is 99:
The aqueous adhesive composition according to any one of claims 1 to 3, wherein the ratio is 1 to 50:50.