JP2000136369A - Water-based adhesive - Google Patents

Abstract

(57) [Problem] To provide a water-based adhesive which gives a film excellent in water resistance, heat resistance and the like. SOLUTION: In an aqueous medium, a polyurethane prepolymer having an isocyanate group in a molecule includes (a)
A vinyl alcohol polymer having at least one functional group selected from a primary amino group, a secondary amino group, a primary hydroxyl group and an acetoacetyl group in the molecule, and (b) a low molecular compound having an amino group or a hydroxyl group in the molecule Aqueous adhesive comprising a polyurethane emulsion obtained by reacting

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel water-based adhesive, and more particularly to a plastic film or an adhesive excellent in bonding a plastic film to various metals, papers, woods and the like.

[0002]

2. Description of the Related Art Conventionally, polyurethane has been used as a resin to fill the boundary field between rubber and plastics by taking advantage of its excellent mechanical properties, abrasion resistance, chemical resistance, adhesiveness, etc., as a resin and a coating agent. , And has permeated a wide range of application fields such as artificial leather. Among them, aqueous polyurethane has been rapidly developed to meet social needs such as environmental conservation, resource saving and safety. High-performance aqueous polyurethanes have emerged due to advances in the technology of emulsifying and dispersing urethane resins in water, the technology of self-emulsifying and dispersing by ionomerization, and the technology of increasing the molecular weight in water. It has reached a comparable level and has been put to practical use in various application fields. However, the emulsifiers and ionic groups required for aqueous conversion often impair the inherent properties of the polyurethane resin, for example, solvent resistance and heat resistance.Furthermore, aqueous polyurethane and various aqueous emulsions are blended. In many cases, there is a problem with miscibility. These improvements have been considerably improved depending on the selection of the emulsifier, the type of ionic group to be introduced, and the like, but in reality, they have not yet reached a satisfactory level.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a water-based polyurethane adhesive having excellent water resistance, heat resistance and the like which does not have the above-mentioned problems under such circumstances. It was done.

[0004]

The present inventors have conducted intensive studies to develop an aqueous adhesive having the above-mentioned preferable properties. As a result, a polyurethane prepolymer having an isocyanate group in a molecule in an aqueous medium has been obtained. (A) a vinyl alcohol polymer having at least one functional group selected from an amino group, a primary hydroxyl group and an acetoacetyl group in the molecule, and (b) a low molecular compound having an amino group or a hydroxyl group in the molecule. Aqueous adhesive comprising the polyurethane emulsion (A) obtained by the reaction, or (A) and an aziridine group, an epoxy group, an oxazoline group,
The present inventors have found that an adhesive containing a compound (B) having two or more functional groups selected from an oxazine group, an isocyanate group and a carbodiimide group in a molecule is a water-based adhesive having the desired performance. Was completed.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polyurethane emulsion (A) used in the present invention is typically prepared by emulsifying a polyurethane prepolymer having an isocyanate group in a molecule in water or after emulsifying the polyurethane prepolymer (a). A) a vinyl alcohol-based polymer having an amino group, a primary hydroxyl group or an acetoacetyl group in the molecule, and (b) a low molecular weight compound having an amino group or a hydroxyl group in the molecule, simultaneously or separately, and reacting them. Polyurethane emulsion.

The polyurethane prepolymer used in the present invention is substantially a molecule obtained by reacting a polymer polyol, an organic diisocyanate and, if necessary, a chain extender in the presence or absence of a solvent. It is a polyurethane having one or more isocyanate groups therein.

The high molecular polyol which can be used for the production of the polyurethane prepolymer includes polyester polyol, polycarbonate polyol, polyester polycarbonate polyol, polyether polyol and the like. It can be formed using two or more kinds.

The polyester polyol used in the production of the polyurethane prepolymer may be prepared, for example, by directly esterifying a polyol component with a polycarboxylic acid component such as a polycarboxylic acid, an ester thereof, or an ester-forming derivative such as an anhydride according to a conventional method. Alternatively, it can be obtained by transesterification.

The polycarboxylic acid component, which is a raw material for producing a polyester polyol used for producing a polyurethane prepolymer, includes, for example, succinic acid, glutaric acid,
Adipic acid, pimelic acid, suberic acid, azelaic acid,
Sebacic acid, dodecanedioic acid, 2-methylsuccinic acid, 2-
Aliphatic dicarboxylic acids such as methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecandioic acid, and 3,7-dimethyldecanedioic acid; isophthalic acid Dicarboxylic acids such as terephthalic acid, phthalic acid and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; tricarboxylic acids such as trimellitic acid and trimesic acid; ester-forming derivatives thereof; And one or more of these can be used. Among them, the polyester polyol is mainly composed of an aliphatic carboxylic acid or an ester-forming derivative thereof as a polycarboxylic acid component, and optionally contains a small amount of a trifunctional or more functional polycarboxylic acid or an ester-forming derivative thereof. It is preferably manufactured.

The polyol component, which is a raw material for producing a polyester polyol used for producing a polyurethane prepolymer, includes, for example, ethylene glycol, propylene glycol, 2-methyl-1,3-propanediol, 1,4-butanediol, , 5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-
Pentanediol, neopentyl glycol, 1,7-
Heptanediol, 1,8-octanediol, 1,9
Aliphatic diols such as nonanediol, 2-methyl-1,8-octanediol and 1,10-decanediol; alicyclic diols such as cyclohexanedimethanol and cyclohexanediol; glycerin, trimethylolpropane, butanetriol, hexane Triol,
Examples thereof include triols such as trimethylolbutane and trimethylolpentane, and tetraols such as pentaerythritol, and one or more of these can be used. Among them, the polyester polyol is preferably made of an aliphatic polyol as a polyol component, and is preferably produced using a polyol component containing a small amount of a trifunctional or higher polyol in some cases.

The polycarbonate polyol which can be used for producing a polyurethane prepolymer is obtained, for example, by reacting a polyol with a carbonate compound such as dialkyl carbonate, alkylene carbonate, diaryl carbonate and the like. As the polyol constituting the polycarbonate polyol, the polyol exemplified above as the constituent component of the polyester polyol can be used. Further, as the dialkyl carbonate, dimethyl carbonate, diethyl carbonate, and the like,
Examples of the alkylene carbonate include ethylene carbonate, and examples of the diaryl carbonate include diphenyl carbonate.

[0012] Polyester polycarbonate polyols that can be used in the production of polyurethane prepolymers include:
For example, a polyol, a product obtained by simultaneously reacting a polycarboxylic acid and a carbonate compound, a product obtained by reacting a polyester polyol and a carbonate compound which have been prepared in advance, a polycarbonate polyol and a polyol which have been prepared in advance And those obtained by reacting a polycarboxylic acid, and those obtained by reacting a polyester polyol and a polycarbonate polyol which have been produced in advance.

Examples of polyether polyols that can be used for producing a polyurethane prepolymer include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. One or more of these may be used. it can.

The number average molecular weight of the high molecular polyol component is 5
00 to 10000, and 700 to 5
000, more preferably 750-4000. Number average molecular weight of 500 to 10000
When a polyurethane prepolymer produced using a high molecular polyol out of the range described above is used, the resulting water-based adhesive composition tends to have reduced heat resistance, water resistance, and the like.

Further, in the high molecular polyol, the number f of hydroxyl groups per molecule is preferably in the range of 2.0 ≦ f ≦ 4.0. More preferably, the range is 2.0 ≦ f ≦ 3.0. The number of hydroxyl groups per molecule f is 2.0 as described above.
When a polyurethane prepolymer obtained using a high molecular polyol in the range of ≦ f ≦ 4.0 is used in the polyurethane emulsion of the present invention, the resulting water-based adhesive composition has good heat resistance and water resistance. .

As the organic diisocyanate component, any of organic diisocyanates conventionally used in the production of ordinary polyurethane-based emulsions can be used. Examples of the organic diisocyanate component include those of alicyclic diisocyanate, aliphatic diisocyanate and aromatic diisocyanate having a molecular weight of 500 or less. One of them
Species or two or more are preferably used. Examples of the organic diisocyanate include hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
Examples thereof include 4,4'-diphenylmethane diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, and 1,5-naphthylene diisocyanate, and one or more of these can be used.

In the production of the polyurethane prepolymer of the present invention, a chain extender component can be used if necessary. As the chain extender component that can be used, any chain extender conventionally used in the production of ordinary polyurethane-based emulsions can be used, but two or more active hydrogen atoms capable of reacting with an isocyanate group in the molecule are used. It is preferable to use a low molecular compound having a molecular weight of 300 or less. For example, ethylene glycol, propylene glycol, 1,
4-butanediol, 1,6-hexanediol, 1,
4-bis (β-hydroxyethoxy) benzene, 1,4
Diols such as cyclohexanediol, bis- (β-hydroxyethyl) terephthalate, xylylene glycol; triols such as trimethylolpropane;
Pentaols such as pentaerythritol; diamines such as hydrazine, ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, piperazine and derivatives thereof, phenylenediamine, tolylenediamine, xylenediamine, adipic dihydrazide and isophthalic dihydrazide; amino Examples thereof include amino alcohols such as ethyl alcohol and aminopropyl alcohol, and one or more of these can be used.

The production of the polyurethane prepolymer can be carried out by a conventionally known method, and can be carried out at a temperature of 30 to 150 ° C. in the presence or absence of an organic solvent. Examples of the organic solvent that can be used in this case include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; esters such as ethyl acetate and butyl acetate; amides such as dimethylformamide and N-methylpyrrolidone; And solvents having a boiling point of less than 100 ° C., such as acetone, methyl ethyl ketone, and ethyl acetate, in consideration of the easiness of solvent removal after emulsion production. Also, after prepolymer production,
The above organic solvent may be added or added for the purpose of lowering the viscosity or the like.

In the production of the polyurethane prepolymer, a reaction catalyst can be added as required. Examples of such a catalyst include tin octylate, monobutyltin triacetate, monobutyltin monooctylate, and monobutyltin monooctylate. Organic tin compounds such as butyltin monoacetate, monobutyltin maleate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin distearate, dibutyltin dilaurate, and dibutyltin maleate; organic compounds such as tetraisopropyl titanate and tetra-n-butyl titanate Titanium compound;
Tertiary amines such as triethylamine, N, N-diethylcyclohexylamine, N, N, N ′, N′-tetramethylethylenediamine and triethylenediamine can be mentioned.

In the production of the polyurethane prepolymer, the ratio (R) of isocyanate group equivalents per equivalent of active hydrogen atoms is 1 based on the total amount of active hydrogen atoms contained in the polymer polyol and the chain extender. .05 ≦ R
It is preferably used in the range of ≦ 3.0, and 1.1 ≦ R ≦
More preferably, it is used in the range of 2.5. R is 1.0
If it is less than 5, the reactivity with the vinyl alcohol-based polymer described below decreases, heat resistance, water resistance, etc. are not sufficiently improved, and emulsification in water due to high viscosity of the prepolymer. Have difficulty. When R exceeds 3.0, the emulsion becomes unstable and tends to gel when it reacts with a vinyl alcohol-based polymer or a low molecular weight compound having an amino group or a hydroxyl group, which will be described later.

Next, the polyurethane prepolymer is emulsified in an aqueous medium. This method includes (1) a method of introducing a hydrophilic group into the polyurethane prepolymer molecule to impart self-emulsifying properties to the prepolymer itself; 2) A method in which a polyurethane prepolymer is forcibly emulsified using a surfactant.

The introduction of a hydrophilic group into the polyurethane prepolymer molecule is achieved by using a compound containing an active hydrogen atom having a hydrophilic group in the above prepolymer reaction. Examples of the active hydrogen atom-containing compound having a hydrophilic group include one or more active hydrogen atoms such as a hydroxyl group or an amino group in a molecule, and a carboxylic acid group, a sulfonic acid group, a carboxylate, a sulfonate, or the like. An anionic group;
Nonionic groups such as polyoxyethylene groups; and compounds having one or more hydrophilic groups selected from cationic groups such as tertiary amino groups and quaternary ammonium salts. For example, carboxylic acid group-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid, and derivatives thereof; 1,3-phenylenediamine-4,6-disulfonic acid Sulfonic acid group-containing compounds such as 2,4-diaminotoluene-5-sulfonic acid and derivatives thereof; molecular weight 200 to 10,000
A nonionic group-containing compound such as polyoxyethylene glycol 0 and its monoalkyl ether; a tertiary amino group-containing compound such as 3-dimethylaminopropanol; and derivatives thereof. Further, a polyester polyol or a polyester polycarbonate polyol obtained by copolymerizing the above active hydrogen atom-containing compound having a hydrophilic group can also be used. Among them, a polyurethane prepolymer is produced using 2,2-dimethylolpropionic acid, and after completion of the prepolymer reaction, a basic substance such as triethylamine, trimethylamine, sodium hydroxide or potassium hydroxide is added to the carboxylate. The conversion method is preferred.

When the polyurethane prepolymer is forcibly emulsified by using a surfactant, the polyurethane prepolymer may not have the above-mentioned hydrophilic group.
As the surfactant, for example, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene lauryl ether,
Nonionic surfactants such as polyoxyethylene stearyl ether and polyoxyethylene-polyoxypropylene block copolymer; sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium alkyldiphenylether disulfonate, di (2-ethylhexyl) ) Anionic surfactants such as sodium sulfosuccinate can be used. Among these, it is preferable to use a nonionic surfactant having an HLB value of 6 to 20.

Emulsification of the polyurethane prepolymer is carried out by using one or both of the above two methods and using an emulsifying and dispersing apparatus such as a homomixer or a homogenizer.
At this time, the emulsification temperature is preferably 40 ° C. or less, more preferably 30 ° C. or less, in order to suppress the reaction between the isocyanate group of the polyurethane prepolymer and water.

Although the particle size of the emulsion obtained by emulsification is not particularly limited, it is usually used by dispersing it to a particle size of 0.1 μm to 100 μm. If the particle size is out of this range, there is a concern that a problem may occur in the stability of the emulsion.

The polyurethane emulsion (A) used in the present invention is a vinyl alcohol polymer having an amino group, a primary hydroxyl group or an acetoacetyl group simultaneously with or after the emulsification of the polyurethane prepolymer, and an amino group in the molecule. And a low molecular compound having an active hydrogen atom selected from hydroxyl groups. The addition of the vinyl alcohol-based polymer and the active hydrogen atom-containing low-molecular compound may be performed simultaneously or separately.

An amino group in the molecule used in the present invention
The vinyl alcohol polymer having a primary hydroxyl group or an acetoacetyl group is not particularly limited as long as it is a vinyl alcohol polymer having an amino group, a primary hydroxyl group or an acetoacetyl group in a molecule. Primary or secondary amino groups are preferred as amino groups. The method for producing a vinyl alcohol polymer having an amino group, a primary hydroxyl group or an acetoacetyl group includes, for example, (1) a primary amino group such as vinyl formamide, methyl vinyl acetamide, hydroxymethyl methacrylate, and hydroxyethyl methacrylate; Copolymerization of vinyl acetate with an ethylenically unsaturated monomer having a secondary amino group or a primary hydroxyl group, or an ethylenically unsaturated monomer having a functional group capable of forming an amino group or a primary hydroxyl group by hydrolysis or the like (2) A primary amino group or a secondary amino group is added to a side chain epoxy group of a polymer obtained by copolymerizing vinyl acetate with a monomer having an epoxy group such as allyl glycidyl ether. Mercaptan containing amino group or primary hydroxyl group is converted to sodium hydroxide (3) a compound having a functional group capable of reacting with a hydroxyl group of polyvinyl alcohol in the molecule and having a primary or secondary amino group or primary hydroxyl group in vinyl alcohol; (4) a method of polymerizing an ethylenically unsaturated monomer having a primary amino group or a secondary amino group or a primary hydroxyl group in the presence of a vinyl alcohol polymer having a mercapto group; (5) a method in which diketene is reacted with a hydroxyl group of polyvinyl alcohol by a solid-gas reaction.

The vinyl alcohol polymer may have a functional group other than an amino group, a primary hydroxyl group or an acetoacetyl group in the molecule as long as the effects of the present invention are not impaired. Examples of monomer units that provide such a functional group include ethylene, propylene, isobutylene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, (anhydrous) fumaric acid, (anhydrous) maleic acid, and (anhydrous)
Itaconic acid, allylsulfonic acid, methallylsulfonic acid,
Vinylsulfonic acid, acrylamide-2-methylpropanesulfonic acid, methacrylamide-2-methylpropanesulfonic acid, sulfopropyl acrylate, sulfopropyl methacrylate, and alkali salts thereof, acrylamide, methacrylamide, trimethyl- (3-acrylamide -3-dimethylpropyl) -ammonium chloride, ethyl vinyl ether, butyl vinyl ether,
Examples include N-vinylpyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, and the like. Further, a polymer having a functional group at a terminal obtained by polymerizing a vinyl ester monomer such as vinyl acetate in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid may be used.

The content of the functional group of the polyvinyl alcohol polymer having at least one functional group selected from amino group, primary hydroxyl group and acetoacetyl group in the molecule constituting the polyurethane emulsion (A) of the present invention is as follows. Although there is no particular limitation, a suitable range varies depending on the degree of polymerization and the like, but is generally preferably 0.1 to 15 mol%.
0.2 to 10 mol% is more preferred. If the amount is less than 0.1 mol%, the reactivity with the polyurethane prepolymer decreases, and the heat resistance, water resistance, and the like are not sufficiently improved.
If it exceeds 15% by weight, the emulsion becomes unstable during the reaction with the polyurethane prepolymer, and the system tends to gel.

The degree of saponification of the vinyl alcohol polymer is as follows:
It is preferably at least 50 mol%, more preferably at least 60 mol%, even more preferably at least 70 mol%. Saponification degree 5
If it is less than 0 mol%, the resulting adhesive or adhesive composition will have insufficient heat resistance, water resistance, and the like. As for the molecular weight of the vinyl alcohol polymer, the viscosity average molecular weight according to the JIS method is preferably from 2,000 to 200,000, and more preferably from 4,000 to 100,000. When the molecular weight is less than 2,000, the resulting adhesive or adhesive composition has insufficient heat resistance and water resistance, and when the molecular weight exceeds 200,000, the reaction with the polyurethane prepolymer occurs. In this case, the emulsion becomes unstable, and the system is easily gelled.

The amount of the vinyl alcohol polymer to be added is from 0.2 to 100 parts by weight of the polyurethane prepolymer.
It is 20 parts by weight, preferably 0.5 to 15 parts by weight. If the amount is less than 0.2 parts by weight, the resulting adhesive or adhesive composition has insufficient heat resistance and water resistance. During the reaction with the polymer, the emulsion becomes unstable, and the system tends to gel. The polyvinyl alcohol-based polymer is usually added in the form of an aqueous solution. Ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; esters such as ethyl acetate and butyl acetate; dimethylformamide and N-methyl It may be added after being dissolved in a mixed solvent of water and an organic solvent such as an amide such as pyrrolidone.

The low molecular weight compound having an amino group or a hydroxyl group in the molecule used in the present invention includes a low molecular weight compound having a molecular weight of 300 or less having an amino group or a hydroxyl group having an active hydrogen atom capable of reacting with an isocyanate group in the molecule. Preferably, a compound is used. Further, a primary or secondary amino group is preferable as the amino 0 group, and a primary hydroxyl group is preferable as the hydroxyl group. For example, triamines such as diethylenetriamine; diamines such as hydrazine, ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, piperazine and derivatives thereof, phenylenediamine, tolylenediamine, xylenediamine, adipic dihydrazide and isophthalic dihydrazide; ethylamine , Monoamines such as propylamine, butylamine, and morpholine; aminoalcohols such as aminoethyl alcohol and aminopropyl alcohol; ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and 1,4-bis (Β-hydroxyethoxy) benzene, 1,4-cyclohexanediol, bis- (β-hydroxyethyl) terephthalate, xylylene glycol And the like. One or more of these can be used.

The amount of the low molecular compound having an amino group or a primary hydroxyl group in the molecule is such that the amount of the active hydrogen atom in the amino group or the hydroxyl group of the low molecular compound is 0 per equivalent of the isocyanate group of the polyurethane prepolymer. .
70 to 1.20 equivalents, preferably 0.75 to
1.15 equivalents is more preferable, and 0.80-1.
More preferably, it is 10 equivalents. If the amount of active hydrogen atoms is less than 0.70 equivalents or exceeds 1.20 equivalents, the degree of polymerization of the polyurethane emulsion will not be sufficiently increased, and heat resistance and water resistance will be insufficient.

The solid content of the polyurethane emulsion used in the present invention is usually adjusted to about 20 to 65% by weight, but is not limited thereto. When an organic solvent is used in the production of the prepolymer, the organic solvent can be removed by distillation or stripping, if necessary.

The polyurethane emulsion (A) used in the present invention generally contains a polymer in which a polyurethane unit and a polyvinyl alcohol unit are bonded by structural units represented by the following general formulas (1) to (3). It is assumed that this contributes to the performance of the adhesive of the present invention.

[0036]

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[0037]

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[0038]

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The aqueous adhesive of the present invention is a compound (B) having two or more functional groups selected from the group consisting of the above (A) and an aziridine group, an epoxy group, an oxazoline group, an oxazine group, an isocyanate group and a carbodiimide group. By using together, a higher adhesive can be obtained. As (B), a water-soluble one or a water-dispersible one is used.

As an example, compounds having two or more epoxy groups in a molecule include bisphenol A diglycidyl ether, bisphenol A diβ methyl glycidyl ether, bisphenol F diglycidyl ether, tetrahydroxyphenylmethane tetraglycidyl ether, resorcinol diglycidyl ether Glycidyl ether, brominated bisphenol A diglycidyl ether, chlorinated bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, diglycidyl ether of bisphenol A alkylene oxide adduct, novolak glycidyl ether, polyalkylene glycol diglycidyl ether, glycerin Triglycidyl ether, pentaerythritol diglycidyl ether, epoxy urethane resin, etc. Glycidyl ether type; glycidyl ether / ester type such as glycidyl ether / ester of P-oxybenzoic acid; diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahexaphthalate, diglycidyl acrylate, dimer Glycidyl ester type such as acid diglycidyl ester; glycidyl aniline,
Glycidylamine type such as tetraglycidyldiaminodiphenylmethane, triglycidylisocyanurate and triglycidylaminophenol; linear aliphatic epoxy resins such as epoxidized polybutadiene and epoxidized soybean oil;
3,4 epoxy-6 methylcyclohexylmethyl-3,4
Epoxy-6 methylcyclohexanecarboxylate,
3,4 epoxycyclohexylmethyl (3,4-epoxycyclohexane) carboxylate, bis (3,4-epoxy-6methylcyclohexylmethyl) adipate,
Examples include alicyclic epoxy resins such as vinylcyclohexene diepoxide, dicyclopentadiene oxide, bis (2,3-epoxycyclopentyl) ether and limonenedioxide, and polyamide epichlorohydrin.

Compounds having an aziridine group in the molecule include 2,4,6-tris (1'-aziridinyl)-
1,3,5-triazine, ω-aziridinylpropionic acid-2,2′-dihydroxymethyl-butanol-triester, 4,4′-bis (ethyleneiminocarbonylamino) diphenylmethane and the like.

Examples of the oxazoline group or a compound having an oxazine group in the molecule include 2,2'-ethylenebis (2-oxazoline), 2,2'-p-phenylenebis (2-oxazoline), 2,2'- Ethylenebis (2-
Oxazine), 2,2′-p-phenylenebis (2-oxazine), unsaturated oxazoline such as 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, or the polymerization of an oxazine compound with another unsaturated compound. And the like.

Compounds having an isocyanate group in the molecule include butane-1,4-diisocyanate and 1,6
-Hexane diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane diisocyanate-
(1,4) 1-methylcyclohexane-2,4-diisocyanate, 1-methylcyclohexane-2,6-diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluylene diisocyanate, Examples thereof include 2,6-toluylene diisocyanate and 4,4'-diphenylmethane diisocyanate. Examples of the compound having a carbodiimide group include ordinary carbodiimide compounds, for example, “Carbodilite V-01,02,0” manufactured by Nisshinbo.
3,04,06 "," Carbodilite HMV-8C "
A "," Carbodilite 10M-SP "," Carbodilite IM-25P "," Carbodilite 9010 ",
"Carbodilite 9010 ST" and the like.

The water-based adhesive of the present invention is characterized in that when a polyurethane prepolymer having an isocyanate group in a molecule is emulsified in water or after emulsification, (a) an amino group, a primary hydroxyl group or an acetoacetyl group And (b) a low molecular weight compound having an active hydrogen atom selected from an amino group and a primary hydroxyl group in a molecule, simultaneously or separately, and a polyurethane emulsion (A ) And a compound (B) having two or more functional groups selected from aziridine group, epoxy group, oxazoline group, oxazine group, isocyanate group and carbodiimide group in the molecule. The blending amount of (A) and (B) is (A) in terms of solid content.
(B) 0.1 to 70 parts by weight, preferably (B) 0.2 to 50 parts by weight, based on 100 parts by weight. Outside of this range, there are problems such as insufficient curing and embrittlement of the coating.

The aqueous adhesive of the present invention may contain an aqueous emulsion, if necessary, in addition to the above (A) and (B). The aqueous emulsion is not particularly limited, but conventionally known urethane dispersion, vinyl acetate polymer emulsion, vinyl acetate- (meth) acrylate copolymer emulsion, ethylene-vinyl acetate copolymer emulsion, ethylene-vinyl acetate −
(Meth) acrylate copolymer emulsion, ethylene-vinyl chloride copolymer emulsion, ethylene-
Vinyl acetate-vinyl chloride copolymer emulsion, ethylene-vinyl acetate-tertiary carboxylic acid vinyl ester copolymer emulsion, (meth) acrylate (co)
Vinyl acetate resin emulsion such as polymer emulsion, styrene- (meth) acrylate copolymer emulsion, styrene-butadiene copolymer emulsion, styrene- (meth) acrylate-butadiene copolymer emulsion, and (meth) acryl Acid ester emulsions and diene resin emulsions are exemplified.

If necessary, various organic solvents such as toluene, perchrene, dichlorobenzene, trichlorobenzene, starch, modified starch, oxidized material, etc. may be used to adjust the drying property, setting property, viscosity, film forming property and the like. Starch, sodium alginate, carboxymethylcellulose,
Water-soluble polymers such as methylcellulose, hydroxymethylcellulose, maleic anhydride / isobutene copolymer, maleic anhydride / styrene copolymer, maleic anhydride / methylvinyl ether copolymer, urea / formalin resin, urea / melamine / folimarin resin , Thermosetting resins such as phenol / holimarin resin, and fillers such as clay, kaolin, talc, calcium carbonate, and wood flour;
Fillers such as flour, reaction accelerators such as boric acid and aluminum sulfate, pigments such as titanium oxide, and various additives such as antifoaming agents, dispersants, antifreezing agents, preservatives, and rust inhibitors are also appropriately used. Can be added.

The water-based adhesive of the present invention can be used for a wide range of applications, for example, adhesion between various plastic films,
It is preferably used for bonding a plastic film to various metals, paper materials, wood and the like.

[0048]

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples,
And "%" mean by weight unless otherwise specified.

Abbreviations in the examples and comparative examples represent the following. PMPA2150: Polyester diol having a number average molecular weight of 2150 (
PMPA3600: polyester diol having a number average molecular weight of 3600 (prepared by reacting 3-methyl-1,5-pentanediol with adipic acid)
PTMG2000: polytetramethylene glycol having a number average molecular weight of 2000 PCL2000: polycaprolactone glycol having a number average molecular weight of 2000 IPDI: isophorone diisocyanate HMDI: methylenebis (4-cyclohexyl) Isocyanate) TDI: 2,4-tolylene diisocyanate DMPA: 2,2-bis (hydroxymethyl) propionic acid TEA: triethylamine DETA: diethylenetriamine IPDA: isophoronediamine EDA: ethylenediamine MEK: 2-butanone

Production Example 1 PMPA2150 537.
5 g, IPDI 111.1 g, DMPA 6.71 g
Was weighed and stirred under a dry nitrogen atmosphere at 90 ° C. for 2 hours to quantitatively react hydroxyl groups in the system to obtain an isocyanate-terminated prepolymer. After adding 202.9 g of MEK to the mixture and uniformly stirring, the temperature in the flask was lowered to 40 ° C., 5.06 g of TEA was added, and the mixture was stirred for 10 minutes. Next, Emulgen 985 (manufactured by Kao,
Nonionic surfactant) 14.5 g and distilled water 420 g
Was added to the prepolymer, and the mixture was stirred with a homomixer for 1 minute to emulsify the mixture. Immediately, amino group-containing polyvinyl alcohol (polyvinyl alcohol obtained by copolymerizing vinyl formamide and vinyl acetate followed by saponification:
Polymerization degree 350, saponification degree 98.5 mol%, primary amino group content 1.5 mol%) 34.0 g, DETA
7.58 g and 12.52 g of IPDA were added to distilled water 6
An aqueous solution dissolved in 52 g was added, and the mixture was stirred with a homomixer for 1 minute to perform a reaction. Thereafter, MEK was removed by a rotary evaporator to obtain a polyurethane emulsion having a solid content of 40% by weight.

Production Example 2 In a three-liter three-necked flask, PMPA3600 540.
0 g, 80.0 g of IPDI, and 6.04 g of DMPA were weighed and stirred at 90 ° C. for 2 hours under a dry nitrogen atmosphere to quantitatively react hydroxyl groups in the system to obtain an isocyanate-terminated prepolymer. After adding 191.4 g of MEK and uniformly stirring, the temperature in the flask was lowered to 40 ° C., and 4.55 g of TEA was added, followed by stirring for 10 minutes. Next, Emulgen 985 (manufactured by Kao,
Nonionic surfactant) 19.1 g was distilled water 397 g
Was added to the prepolymer, and the mixture was stirred with a homomixer for 1 minute to emulsify. Immediately after copolymerization of amino group-containing polyvinyl alcohol (allyl glycidyl ether and vinyl acetate), 2-aminothiophenol was added to N
Polyvinyl alcohol obtained by adding aOH as a catalyst and further saponifying: polymerization degree 500, saponification degree 97.5 mol%, primary amino group modification amount 1.0 mol
%) Dissolved in 420 g of distilled water and stirred with a homomixer for 30 seconds.
An aqueous solution in which 10.21 g was dissolved in 240 g of distilled water was added, and the mixture was stirred with a homomixer for 1 minute to perform a reaction. Thereafter, MEK was removed by a rotary evaporator to obtain a polyurethane emulsion having a solid content of 40% by weight.

Production Example 3 PTMG2000 250.
0 g, PCL20000250.0 g, HMDI 11
8.1 g and 6.71 g of DMPA were weighed and stirred at 80 ° C. for 2 hours in a dry nitrogen atmosphere to quantitatively react hydroxyl groups in the system to obtain an isocyanate-terminated prepolymer. After 188.7 g of MEK was added thereto and uniformly stirred, the temperature in the flask was lowered to 40 ° C., and TEA 5.0 was added.
6 g was added and the mixture was stirred for 10 minutes. Next, an aqueous solution in which 6.7 g of Emulgen 985 (manufactured by Kao, nonionic surfactant) and 6.7 g of Emulgen 930 (manufactured by Kao, nonionic surfactant) were dissolved in 392 g of distilled water was added to the prepolymer as an emulsifier, and the mixture was homogenized. After stirring with a mixer for 1 minute to emulsify, immediately amino-containing PVA (after copolymerizing methyl vinyl acetamide and vinyl acetate,
Polyvinyl alcohol obtained by saponification: 32.2 g of degree of polymerization 750, degree of saponification 87.5 mol%, secondary amino group modification amount 2.5 mol%), DETA 6.81
g and IPDA (5.62 g) in distilled water (620 g) were added, and the mixture was stirred for 1 minute with a homomixer to carry out a reaction. Thereafter, MEK was removed by a rotary evaporator to obtain a polyurethane emulsion having a solid content of 40% by weight.

Production Example 4 PMPA2150 537.
5 g, 87.1 g of TDI, and 6.71 g of DMPA were weighed, and stirred at 70 ° C. for 2 hours under a dry nitrogen atmosphere to quantitatively react hydroxyl groups in the system to obtain an isocyanate-terminated prepolymer. After adding 194.6 g of MEK thereto and uniformly stirring, the temperature in the flask was lowered to 40 ° C.
5.06 g of TEA was added and stirred for 10 minutes. Next, 16.5 g of Emulgen 985 (a nonionic surfactant manufactured by Kao) as an emulsifier and polyvinyl alcohol containing acetoacetyl group (polyvinyl alcohol obtained by reacting diketene with polyvinyl alcohol by a solid-gas reaction: degree of polymerization: 1000, degree of saponification) An aqueous solution in which 32.4 g of 97.5 mol%, acetoacetyl group content of 5 mol%) was dissolved in 520 g of distilled water was added to the prepolymer, and the mixture was emulsified by stirring with a homomixer for 1 minute.
An aqueous solution obtained by dissolving 7.59 g of ETA and 4.42 g of EDA in 494 g of distilled water was added, and the mixture was mixed with a homomixer.
The reaction was carried out by stirring for minutes. Thereafter, the MEK was removed by a rotary evaporator, and the solid content was 40 wt%.
Thus, a polyurethane-based emulsion was obtained.

Production Example 5 PMPA2150 537.
5 g, IPDI 194.5 g, DMPA 33.53
g and 249.1 g of MEK were weighed and stirred at 60 ° C. for 8 hours in a dry nitrogen atmosphere to quantitatively react the hydroxyl groups in the system to obtain an isocyanate-terminated prepolymer. Thereafter, the temperature in the flask was lowered to 40 ° C., and TEA 25.
30 g was added and the mixture was stirred for 30 minutes. Next, 720.0 g of distilled water was added and the mixture was stirred to emulsify the polyurethane prepolymer in water. Immediately after the copolymerization of primary hydroxyl group-containing polyvinyl alcohol (allyl glycidyl ether and vinyl acetate), 2-mercaptoethanol was converted to NaOH Was added as a catalyst and further saponified. Polyvinyl alcohol: degree of polymerization 500, degree of saponification 97.5 mol%, primary hydroxyl group modification amount 1.0 mol
%) 41.8 g, DETA 17.02 g and IPD
An aqueous solution in which 14.05 g of A was dissolved in 576 g of distilled water was added, and the mixture was stirred for 1 minute with a homomixer to perform a reaction.
Thereafter, MEK was removed by a rotary evaporator to obtain a polyurethane emulsion having a solid content of 40% by weight.

Comparative Production Example 1 A polyurethane emulsion was obtained in the same manner as in Production Example 1, except that no amino group-containing polyvinyl alcohol was used.

Examples 1 to 10 and Comparative Examples 1 to 3 Adhesives were prepared according to the composition shown in Table 1, and a soft PV was prepared.
The C sheet and the Lauan plywood were bonded together, and the following adhesion test was performed. Table 2 shows the results. (Adhesion conditions) Adherend: Soft PVC sheet 1 mm thick / Lauan plywood (Type # 1, 5.5 mm thick) Coating amount: 10 g / 30 × 30 cm Curing: After applying and bonding, lightly pressing with a rubber hand roller, 3 Curing at 20 ° C and 65% RH for 60 days (Test conditions) Normal strength: Cut out to inch width and peel 180 degrees as it is (200 mm / min) Water resistance strength: After 24 hours immersion in water, peel 180 degrees wet (200 mm / min) Heat resistance creep: 80 ° C, 95% RH, 90 degree angle, 1k
Length peeled by g load

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

The water-based adhesive of the present invention can be used for a wide range of applications because it gives a film having excellent water resistance and heat resistance.
For example, it is preferably used for bonding various plastic films or bonding plastic films to various metals, paper materials, wood, and the like.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masato Nakamae 3-8-2 Nihonbashi, Chuo-ku, Tokyo F-term in Kuraray Co., Ltd. F-term (reference) 4J034 BA08 CA03 CA04 CA14 CA15 CC03 CC23 CC26 DA01 DA03 DB04 DB05 DF01 DF02 DF03 DF19 DF20 DF21 DF22 DG02 HA01 HA06 HA07 HC03 HC12 HC13 HC17 HC22 HC71 HC73 JA13 JA41 JA42 KA01 KC16 KC17 KD02 KD04 KD12 MA12 MA14 QC05 RA08 4J040 EC032 EC052 EC062 EC072 EC102 EC112 EC122 EC152 EC162 EC202 EC242 EC252 EF051 EF061 EF181 EF191 EF321 GA03 GA05 GA06 GA07 GA12 GA13 GA14 GA22 GA24 GA25 HA126 HC16 HC22 HC25 HC26 JA03 JB11 KA16 LA01 LA07 LA08 MA02 MA08 MA09 MA10

Claims (2)

[Claims] In an aqueous medium, a polyurethane prepolymer having an isocyanate group in a molecule is provided with (a)
Obtained by reacting a vinyl alcohol polymer having at least one functional group selected from an amino group, a primary hydroxyl group and an acetoacetyl group in the molecule, and (b) a low molecular compound having an amino group or a hydroxyl group in the molecule. An aqueous adhesive made of a polyurethane emulsion. 2. The polyurethane emulsion (A) according to claim 1 and a compound (B) having at least two functional groups selected from an aziridine group, an epoxy group, an oxazoline group, an oxazine group, an isocyanate group and a carbodiimide group in a molecule. Aqueous adhesive comprising: