JP2003064294A - Cold-drying aqueous coating agent - Google Patents

Abstract

(57) [Summary] [Problem] Excellent low-temperature film-forming properties without using a volatile organic compound such as a film-forming aid or an antifreezing agent that causes health problems, and has blocking resistance and low-temperature stability. To provide an air-drying coating agent excellent in properties. SOLUTION: The copolymer comprises an aqueous urethane resin (A) and a copolymer (B) having a glass transition temperature of 5 ° C. or more obtained by copolymerizing an ethylenically unsaturated monomer, and a solid content ratio by weight. Contains (A) :( B) = 10: 90 to 90:10 as an essential component, and the content of the volatile organic compound having a boiling point of 50 to 250 ° C. in the total amount of the coating agent 1% by weight or less of the air-drying aqueous coating composition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coating agent applicable to various base materials such as inorganic base materials, organic base materials, metal base materials, etc., without adding a film forming aid, an antifreezing agent, etc. In particular, the present invention relates to a normally dry water-based coating material which has good film-forming property at low temperature, low temperature stability, and excellent blocking resistance.

[0002]

2. Description of the Related Art In recent years, from the viewpoints of protection of the global environment and occupational health, various coating agents are being changed from solvent-based to water-based. In the field of architectural paints, emulsion paints, which are water-based coatings, have been the mainstream for a long time, but recently health problems caused by trace amounts of volatile organic compounds contained in building materials and auxiliary materials have become a problem. However, it is urgent to remove or reduce these. Emulsion paint contains far less volatile organic compounds than solvent-based paint. However, it is a reality that the present emulsion paint contains a volatile organic compound as a film-forming aid, an antifreezing agent, etc. in the paint in an amount of several percent, and in the case of a large amount, tens of percent.

Under such circumstances, from the viewpoint of health problems, emulsion paints in which these volatile organic compounds are reduced or not contained are desired. In order to satisfy this requirement, an emulsion that does not contain a film-forming aid is formed in the winter, that is, a film is formed at a low temperature and has low-temperature stability (freeze-thaw stability) without using an antifreezing agent. Development is essential. In order to form a film at a low temperature without containing a film-forming auxiliary, the emulsion resin can be softened, that is, a minimum film-forming temperature of 0 ° C. or less can be used. However, if the emulsion resin is softened, the blocking resistance is deteriorated, and as a result, the stain resistance is deteriorated when the emulsion paint is prepared. In addition, this method cannot be expected to improve the low temperature stability.

Therefore, there is an urgent need to develop an emulsion resin which does not contain a film-forming auxiliary and has a low-temperature film-forming property while maintaining anti-blocking property, and has a low-temperature stability even when it does not contain an antifreezing agent. Has been done. For example, it has been proposed that an emulsion resin having both blocking resistance and film-forming property can be obtained by blending a hard emulsion and a soft emulsion. Although the blocking resistance is improved by this method, the balance between the blocking resistance / film forming property is not yet sufficient.

A method using a core / shell emulsion composed of a hard component and a soft component has also been proposed, but this method also improves the balance of blocking resistance / film forming property, but is not sufficient. I can not say. Further, the effect of improving the low temperature stability is not sufficient by any of these methods.

[0006]

The problem to be solved by the present invention is to achieve low-temperature film-forming properties without using volatile organic compounds such as film-forming aids and antifreezing agents which cause health problems. An object of the present invention is to provide a normally dry coating agent which is excellent in blocking resistance and low temperature stability.

[0007]

Means for Solving the Problems As a result of intensive investigations, the present inventors have found that an aqueous urethane resin (A), preferably an aqueous urethane resin (A) having a glass transition temperature of 0 ° C. or lower, and an ethylenically unsaturated monomer. An aqueous coating agent containing as an essential component an aqueous resin dispersion (C) in which a polymer (B) having a glass transition temperature of 5 ° C. or higher obtained by copolymerizing a monomer is used in a specific composition range, Even if the content of the volatile organic compound having a boiling point of 50 to 250 ° C. is 1% by weight or less in the total amount of the coating agent,
The inventors have found that they have excellent low-temperature film-forming properties as well as excellent blocking resistance and low-temperature stability, and have completed the present invention.

That is, the present invention is based on the aqueous urethane resin (A),
Preferably, an aqueous urethane resin (A) having a glass transition temperature of 0 ° C. or lower and a copolymer (B) having a glass transition temperature of 5 ° C. or higher obtained by copolymerizing an ethylenically unsaturated monomer And the solid content weight ratio is (A) :( B)
= 10:90 to 90:10 aqueous resin dispersion (C)
And an volatile organic compound having a boiling point of 50 to 250 ° C. in an amount of 1% by weight or less based on the total amount of the coating agent.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The details of the invention will be described below. There are no particular conditions for the aqueous urethane resin (A) used in the present invention, but it is preferable to use a water-dispersible urethane resin having a glass transition temperature of 0 ° C. or lower or a water-soluble urethane resin from the viewpoint of low-temperature film-forming property. The water-based urethane resin (A) is water-dispersed or water-solubilized with an emulsifier or the like, or is self-dispersed or water-solubilized by introducing a hydrophilic group into the urethane resin skeleton. Any of these can be used regardless of the form.
However, among these, it is preferable to introduce a hydrophilic group such as a carboxyl group into the urethane skeleton and use a self-dispersed or water-solubilized one from the viewpoint of film-forming property / blocking resistance.

The method for producing the aqueous urethane resin (A) used in the present invention is not particularly limited, but for example, it can be produced by the following method.

If necessary, a neutralizing agent is added to an organic solvent solution or an organic solvent dispersion of a hydrophilic group-containing polyurethane resin obtained by reacting an active hydrogen-containing compound and a hydrophilic group-containing compound with a polyisocyanate. A method in which an aqueous urethane resin is obtained by mixing an aqueous solution containing the above and removing the solvent as necessary.

Aqueous solution containing a neutralizing agent in a urethane prepolymer containing a hydrophilic group and having an isocyanate group at the terminal, which is obtained by reacting an active hydrogen-containing compound and a hydrophilic group-containing compound with polyisocyanate. Or a method in which a neutralizing agent is added to the prepolymer in advance and then water is mixed and dispersed in water, and then reacted with polyamine to obtain an aqueous urethane resin.

A urethane prepolymer containing a hydrophilic group and having an isocyanate group at its end, which is obtained by reacting an active hydrogen-containing compound and a hydrophilic group-containing compound with a polyisocyanate, a neutralizing agent and a polyamine A method of obtaining an aqueous urethane resin by mixing with an aqueous solution containing the above or by adding a neutralizing agent to a prepolymer in advance and then mixing with an aqueous solution containing a polyamine.

As the polyisocyanate used for producing the above-mentioned aqueous urethane resin (A), for example, 2,4-
Tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 3,3 '-Dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-
4,4'-biphenylene diisocyanate,

1,5-naphthalene diisocyanate,
1,5-tetrahydronaphthalene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,
3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 3,3′- Dimethyl-4,4'-dicyclohexylmethane diisocyanate and the like can be mentioned.

The active hydrogen-containing compound used in the production of the aqueous urethane resin (A) can react with an isocyanate group, and has an average molecular weight of 300 to 10, for convenience.
000, preferably 500 to 5,000, and high molecular weight compounds, and low molecular weight compounds having a molecular weight of 300 or less.

Among the active hydrogen-containing compounds, the high molecular weight compounds include, for example, polyester polyols, polyether polyols, polycarbonate polyols, polyacetal polyols, polyacrylate polyols, polyester amide polyols, polythioether polyols, polybutadiene-based polyolefin polyols and the like. Is mentioned.

As the polyester polyol, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol,
1,6-hexanediol, neopentyl glycol,
Diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (molecular weight 300 to 6,000), dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A, a glycol component such as hydrogenated bisphenol A, hydroquinone and their alkylene oxide adducts,

Succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4
-Cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid,
2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid,
1,2-bis (phenoxy) ethane-p, p'-dicarboxylic acid and anhydrides or ester-forming derivatives of these dicarboxylic acids; p-hydroxybenzoic acid, p- (2-
(Hydroxyethoxy) benzoic acid, and polyesters obtained by dehydration condensation reaction with acid components such as ester-forming derivatives of these hydroxycarboxylic acids,

Further, a polyester obtained by a ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone,

And polyesters obtained by reacting two or more kinds of polyesters selected from the above polyesters.

As the polyether polyol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, Glycerin, trimethylolethane, trimethylolpropane, sorbitol, sucrose, aconit sugar, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, diethylenetriamine, triisopropanolamine, pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acid, 1,2, Ethylene oxide, propylene oxide using, as an initiator, one or more compounds having at least two active hydrogen atoms such as 3-propanetrithiol. Butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, cyclohexylene, those one or more of the monomers equal by addition polymerization by a conventional method.

As the polycarbonate polyol,
1,4-butanediol, 1,6-hexanediol,
Examples thereof include compounds obtained by reacting a glycol such as diethylene glycol with diphenyl carbonate or phosgene.

Among the active hydrogen-containing compounds described above, the low molecular weight compound is a compound having a molecular weight of 300 or less and containing at least two or more active hydrogens.
Glycol components used as raw materials for polyester polyols; polyhydroxy compounds such as glycerin, trimethylolethane, trimethylolpropane, sorbitol, pentaerythritol; ethylenediamine, 1,6-
Hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,
Examples thereof include amine compounds such as 4′-dicyclohexylmethanediamine, 1,4-cyclohexanediamine, 1,2-propanediamine, hydrazine, diethylenetriamine and triethylenetetramine.

The hydrophilic group-containing compound used for producing the above-mentioned aqueous urethane resin (A) is used for introducing a hydrophilic group into the aqueous urethane resin (A), and for example, at least in the molecule. It has one or more active hydrogen atoms and is composed of carboxylic acid salt, sulfonic acid salt, phosphoric acid salt, quaternary ammonium salt, carboxylic acid group, sulfonic acid group, phosphoric acid group, and tertiary amino group. A basically ionic compound containing at least one functional group selected from the group, or a group having at least one or more active hydrogen atoms in the molecule and comprising an ethylene oxide repeating unit, an ethylene oxide repeating unit And a nonionic compound containing a group consisting of other repeating units of alkylene oxide. Among these hydrophilic groups, an anionic group consisting of a carboxylic acid group and a salt of a carboxylic acid, and / or a nonionic group containing a repeating unit of ethylene oxide is particularly preferable.

Specific examples of the hydrophilic group-containing compound include 2-oxyethanesulfonic acid, phenolsulfonic acid, sulfobenzoic acid, sulfosuccinic acid, 5-sulfoisophthalic acid, sulfanilic acid and 1,3-phenylenediamine-4. , 6-Disulfonic acid, 2,4-diaminotoluene-5-sulfonic acid and other sulfonic acid-containing compounds and their derivatives, or polyester polyols produced by using these as a part of raw materials;

2,2-dimethylolpropionic acid, 2,
2-dimethylol butyric acid, 2,2-dimethylol valeric acid,
Dioxymaleic acid, 2,6-dioxybenzoic acid, 3,
Carboxylic acid-containing compounds such as 4-diaminobenzoic acid and derivatives thereof, or polyester polyols produced by using these as a part of raw materials;

Tertiary amino group-containing compounds such as methyldiethanolamine, butyldiethanolamine, alkyldiisopropanolamine, etc. and their derivatives or polyester polyols or polyether polyols produced by using these as a part of raw materials; Group-containing compounds and their derivatives, or polyester polyols or polyether polyols produced by using these as a part of raw materials, and methyl chloride, methyl bromide, dimethyl sulfate, diethyl sulfate, benzyl chloride, benzyl bromide with these , A reaction product of a quaternizing agent such as ethylene chlorohydrin, ethylene bromohydrin, epichlorohydrin, brombutane;

It contains at least 30% by weight of repeating units of ethylene oxide and has at least 1 unit in the polymer.
Molecular weight 300 to 20,000 containing one or more active hydrogens
0, polyoxyethylene glycol or polyoxyethylene-polyoxypropylene copolymer glycol, polyoxyethylene-polyoxybutylene copolymer glycol, polyoxyethylene-polyoxyalkylene copolymer glycol or nonionics such as monoalkyl ethers thereof Examples thereof include group-containing compounds and polyester polyether polyols obtained by copolymerizing these compounds, and these can be used alone or in combination.

When the aqueous urethane resin (A) used in the present invention is produced, the content of the hydrophilic group bonded in the molecule is such that the hydrophilic group is an ionic group such as a carboxyl group or a sulfonic acid group. Is at least 0.005 per 100 parts by weight of the finally obtained aqueous urethane resin solid content.
To 0.2 equivalents, preferably 0.01 to 0.1 equivalents, and a hydrophilic group such as a carboxyl group is particularly preferable.

When the nonionic compound is used, the content is 1% by weight of the finally obtained aqueous urethane resin solid content.
The amount is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, per 100 parts by weight.

In the present invention, an external emulsifier can be used in combination with the hydrophilic group-containing compound. Examples of such emulsifiers include nonionic emulsifiers such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrenated phenyl ether, and polyoxyethylene sorbitol tetraoleate; fatty acid salts such as sodium oleate; Anionic emulsifiers such as ester salts, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, sodium alkane sulfonates, sodium alkyl diphenyl ether sulfonates; polyoxyethylene alkyl sulphates, polyoxyethylene alkyl phenyl sulphates Examples include nonionic anionic emulsifiers such as salts.

The above-mentioned manufacturing method according to the present invention,
The hydrophilic group-containing polyurethane resin and the terminal isocyanate group-containing urethane prepolymer used in, are produced by a conventionally known method, for example, the polyisocyanate and the active hydrogen-containing compound (including the hydrophilic group-containing compound),
In the case of the polyurethane resin, the equivalent ratio of the isocyanate group and the active hydrogen group is 0.8: 1 to 1.2: 1, preferably 0.9: 1 to 1.1: 1, and the terminal isocyanate group is contained. In the case of urethane prepolymer, 1.
The reaction is carried out at a ratio of 1: 1 to 3: 1, preferably 1.2: 1 to 2: 1 at 20 to 120 ° C, preferably 30 to 100 ° C.

These reactions can be carried out in the absence of a solvent, but an organic solvent can be used for the purpose of controlling the reaction of the reaction system or reducing the viscosity. The organic solvent is not particularly limited, but examples thereof include aromatic hydrocarbons such as toluene and xylene; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; acetic acid esters such as ethyl acetate and butyl acetate; dimethylformamide, N Amides such as methylpyrrolidone. In this application, since it is necessary to remove the organic solvent by distillation from the finally obtained aqueous urethane resin, it is preferable to use an organic solvent having a relatively low boiling point, which is easily removed by distillation. Even when it is necessary to use an organic solvent having a boiling point of 100 ° C. or higher, it is preferable to keep the amount used to the minimum necessary.

Examples of the neutralizing agent that can be used in the production of the aqueous urethane resin (A) include non-volatile bases such as sodium hydroxide and potassium hydroxide; trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine, triethanol. Examples include tertiary amines such as amines and volatile bases such as ammonia.

Examples of the polyamine that can be used in the production of the aqueous urethane resin (A) include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2-methylpiperazine, 2, and the like.
5-dimethylpiperazine, isophoronediamine, 4,
4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine,
Diamines such as 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, aminopropylethanolamine, aminohexylethanolamine, aminoethylpropanolamine, aminopropylpropanolamine and aminohexylpropanolamine; diethylenetriamine, Examples include polyamines such as dipropylenetriamine and triethylenetetramine; hydrazines; acid hydrazides and water, and these may be used alone or in combination.

When the aqueous urethane resin thus obtained contains an organic solvent, it is removed by distillation before use. Various types of distillation apparatuses can be used for removing the organic solvent by distillation, but a distillation apparatus that does not release the distilled solvent and the organic solvent that has been distilled off to the atmosphere is preferable, and a thin-film evaporation apparatus is particularly preferable.

The copolymer (B) having a glass transition temperature of 5 ° C. or higher obtained by copolymerizing an ethylenically unsaturated monomer is a copolymer of an ethylenically unsaturated monomer, and Any material having a glass transition temperature of 5 ° C. or higher can be used. That is, a so-called emulsion resin produced by emulsion-polymerizing an ethylenically unsaturated monomer, or ethylene containing an ethylenically unsaturated monomer containing a hydrophilic group such as a carboxyl group in an organic solvent as an essential component. Solution polymerization of polyunsaturated monomer,
An aqueous resin obtained by phase inversion emulsification and solvent removal can be used. Above all, it is preferable to use an emulsion resin produced by emulsion polymerization from the viewpoint of durability, ease of production, and the like. Further, as the ethylenically unsaturated monomer, it is preferable to use an acrylic monomer as an essential component.

The glass transition temperature (hereinafter abbreviated as Tg) of the copolymer (B) having a glass transition temperature of 5 ° C. or higher obtained by copolymerizing an ethylenically unsaturated monomer is generally well known. It is a value calculated by the formula shown below. The Tg of the homopolymer used for the calculation is shown below. As for Tg, which is not described below, the value generally described in the literature can be used. It can also be determined by measurement using a differential scanning calorimetry method or a dynamic viscoelasticity measurement method.

[Formula of Fox] 1 / Tg = Σ (Wn / Tgn) Tg: Glass transition temperature of polymer (absolute temperature) Wn: Weight fraction of monomer n Tgn: Homopolymer of monomer n Glass transition temperature (absolute temperature)

[Tg of Homopolymer] Homopolymer of 2-ethylhexyl acrylate (2EHA): -55.3 ° C. Butyl acrylate (BA) homopolymer: -45.4
C. Methyl methacrylate (MMA) homopolymer: 10
4.2 ° C. Styrene (St) homopolymer: 100.0 ° C. Methacrylic acid (MAA) homopolymer: 143.5 ° C. Acrylic acid (AA) homopolymer: 86.6 ° C. Glycidyl methacrylate (GMA) homo. polymer:
46.3 ° C Homopolymer of diacetone acrylamide (DAA
M): 65.0 ° C. (hereinafter, described using the abbreviations in the parentheses above).

On the other hand, the glass transition temperature of the aqueous urethane resin (A) does not have the concept of being obtained by calculation as described above, and the glass transition temperature can be obtained by measurement.
In this case, the value measured by the differential scanning calorimetric method or the dynamic viscoelasticity measuring method is preferable. In particular, it is preferable to use the maximum value of the loss elastic modulus measured by the dynamic viscoelasticity measuring method. The minimum film forming temperature is a value determined by the method specified in JIS-K-6828.

The emulsion resin can be produced by a known method. To give one example, 0.01 to 10 parts by weight of a radical polymerization initiator is used per 100 parts by weight of an ethylenically unsaturated monomer, and an aqueous medium is 50 to 1000.
0 parts by weight can be used to polymerize in the presence of an emulsifier at 0-100 ° C. In addition, the above-mentioned initiator and reducing agent 0.01
It can also be carried out by redox polymerization using 10 to 10 parts by weight. At this time, a compound that generates a polyvalent metal salt ion such as iron ion or copper ion can be used together as an accelerator.

The ethylenically unsaturated monomer that can be used here is not particularly limited, and any one that is generally used for polymerization can be used. Specific examples include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate. , Methacrylic acid esters such as cyclohexyl methacrylate;

Esters of maleic acid, fumaric acid, and itaconic acid; vinyl esters such as vinyl acetate, vinyl propionate, and tertiary vinyl carboxylate; aromatic vinyl compounds such as styrene and vinyltoluene; vinylpyrrolidone. Heterocyclic vinyl compounds; vinyl chloride, acrylonitrile, vinyl ethers, vinyl ketones, vinylamides; vinylidene halide compounds such as vinylidene chloride, vinylidene fluoride; α-olefins such as ethylene and propylene; and dienes such as butadiene. ,

If desired, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid,
Carboxyl group-containing ethylenically unsaturated monomers such as itaconic acid half ester, maleic acid half ester, maleic anhydride, itaconic anhydride, and 2-methacryloylpropionic acid; α, β- such as acrylamide, methacrylamide, and maleic acid amide. Amides of ethylenically unsaturated acids; glycidyl group-containing monomers such as glycidyl methacrylate and allyl glycidyl ether; hydroxyl group-containing monomers such as 2-hydroxyl ethyl methacrylate and 2-hydroxyl ethyl acrylate;

Amino group-containing monomer such as dimethylaminoethyl methacrylate; Substituted amide of unsaturated carboxylic acid such as N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide; γ-
Unsaturated bond-containing silane compound such as methacryloxypropyltrimethoxysilane; a single compound having two or more unsaturated bonds in one molecule such as diallyl phthalate, divinylbenzene, allyl acrylate, trimethylolpropane trimethacrylate and ethylene glycol dimethacrylate. Mention may also be made. It is of course possible to use two or more kinds of ethylenically unsaturated monomers in combination. Also,
Among these, it is preferable to use acrylic acid ester or methacrylic acid ester as an essential component.

An emulsifier is generally used in emulsion-polymerizing the ethylenically unsaturated monomer, but the emulsifier used here is not particularly limited, and any emulsifier generally used in the emulsion polymerization reaction can be used. However, it can be used. As an example, anionic emulsifiers such as alkylbenzene sulfonates, alkyl sulfates, polyoxyethylene alkylphenyl sulfonates, and dialkylsulfosuccinate salts, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, and polyoxyethylene alkylphenyl ethers. Examples thereof include nonionic emulsifiers such as ethylene-polyoxypropylene block copolymers.

Further, vinyl sulfonates, acrylic acid polyoxyethylene sulphates, methacrylic acid polyoxyethylene sulphonates, polyoxyethylene alkenylphenyl sulphonates, polyoxyethylene alkenyl phenyl sulphates, sodium allylalkyl sulphosuccinates. Anionic reactive emulsifiers such as methacrylic acid polyoxypropylene sulfonate and nonionic reactive emulsifiers such as polyoxyethylene alkenyl phenyl ether and polyoxyethylene methacryloyl ether can also be used. Of course, it is possible to use a plurality of these emulsifiers.

Of course, the kind of the emulsifier is not limited to the above structure, any emulsifier can be used, and generally commercially available ones can be used. Recently, a method of emulsion polymerization without using an emulsifier, that is, soap-free polymerization has been frequently performed, but an aqueous dispersion polymerized by this method can also be used.

Examples of the radical polymerization initiator include persulfates such as potassium persulfate, ammonium persulfate and sodium persulfate, azobisisobutyronitrile and its hydrochloride, 2,2'-azobis (2- Amid initiators such as amidinopropane) dihydrochloride and 4,4'-azobis (4-cyanovaleric acid), and peroxide initiators such as hydrogen peroxide, tertiary butyl hydroperoxide, cumene hydroperoxide Etc. Examples of reducing agents that can be used in combination with these radical initiators include sodium sulfoxylate formaldehyde, sodium pyrosulfite, and L-ascorbic acid. In addition, mercaptans, alcohol organic solvents, aliphatic organic solvents, aromatic organic solvents and the like can be used together as a molecular weight modifier.

In the present invention, the aqueous urethane resin (A)
An aqueous resin dispersion (C) consisting of a copolymer (B) having a glass transition temperature of 5 ° C. or higher, obtained by copolymerizing an ethylenically unsaturated monomer with As the amount, (A) :( B) = 10: 90-9
Within the range of 0:10, preferably (A) :( B) =
It is in the range of 10:90 to 60:40. Within this range, durability such as water resistance, blocking resistance, low-temperature film-forming property, and low-temperature stability will be excellent.
Further, by using the aqueous urethane resin (A) having a glass transition temperature of 0 ° C. or less, it becomes possible to provide a coating material having a better low-temperature film-forming property.

Further, the use of the water-based urethane resin (A) having a smaller average particle diameter, specifically, 100 nm or less makes it possible to obtain a resin having a higher effect of the present invention. The average particle size referred to here means a volume average particle size measured by a light scattering particle size measuring device. Further, by using a polyether-based urethane resin as the water-based urethane resin (A), the low-temperature film-forming property can be further improved.

In the present invention, the method for producing the aqueous resin dispersion (C) is not particularly limited as long as it is a constitutional body comprising the aqueous urethane resin (A) and the copolymer (B).
That is, by copolymerizing an ethylenically unsaturated monomer in the presence of an aqueous resin dispersion (C) obtained by blending the aqueous urethane resin (A) and the copolymer (B), and the aqueous urethane resin (A). The obtained aqueous resin dispersion (C) or the aqueous resin dispersion (C) obtained by copolymerizing an ethylenically unsaturated monomer in the presence of the aqueous urethane resin (A) is further added with an aqueous urethane resin. The excellent effect can be exhibited in any of those obtained by blending.

In the present invention, a pigment may be incorporated in addition to the aqueous resin dispersion (C). The amount to be used is not particularly limited and any amount can be present, but from the viewpoint that the effect of the present invention is more excellent, the pigment is added per 100 parts by weight of the aqueous resin dispersion (C). It is preferably 200 parts by weight or less, more preferably 5 parts by weight or more and 200 parts by weight or less.

The pigments referred to herein include commonly used pigments, fillers and coloring pigments such as titanium oxide, calcium carbonate, talc, clay, mica, silica sand, red iron oxide, carbon black and phthalocyanine blue. It is meant.

If necessary, the present coating agent is a filler,
It is also possible to add an aggregate, a dispersant, a wetting agent, a thickening agent, a rheology control agent, an antifoaming agent, an antiseptic agent, an antifungal agent, a pH adjusting agent, an anticorrosive agent and the like. Further, if the content of the volatile organic compound in the total amount of the present coating agent is within the range of 1% by weight or less, a film-forming auxiliary agent and an antifreezing agent can be added as necessary. For example, in the case of permanent dry paint,
A pigment paste in which pigments such as titanium oxide and calcium carbonate are finely dispersed using a dispersant or the like is an aqueous resin dispersion (C).
Then, a coating agent for a constantly dry building paint can be obtained by letting it down and adding a thickener, a preservative and the like as required.

In order to attain a higher level in the balance of low temperature film-forming property, low temperature stability and blocking resistance, the aqueous urethane resin (A) has a reactive functional group (a) and has a copolymer It is preferable that the combination (B) has a reactive functional group (b) that is reactive with the reactive functional group (a). Specific examples of the reactive functional group (a) included in the aqueous urethane resin (A) include a carboxyl group, an amino group, a hydrazide group, a carbonyl group, a hydroxyl group, a glycidyl group, an amide group, an oxazoline group, and an alkoxysilyl group. To be

When the reactive functional group (a) is a carboxyl group, the reactive functional group (b) includes glycidyl group, ethyleneimine group, hydroxyl group, amide group, oxazoline group and the like. When the reactive functional group (a) is an amino group, the reactive functional group (b) is a glycidyl group, an ethyleneimine group,
An amide group may be mentioned. When the reactive functional group (a) is a hydrazide group, the reactive functional group (b) is a carbonyl group,
An amide group may be mentioned. When the reactive functional group (a) is a carbonyl group, the reactive functional group (b) may be a hydrazide group. When the reactive functional group (a) is a hydroxyl group,
Examples of the reactive functional group (b) include a glycidyl group, an ethyleneimine group, a carboxyl group, an amide group and an oxazoline group. When the reactive functional group (a) is an amide group, the reactive functional group (b) is a glycidyl group, an ethyleneimine group,
Examples thereof include a carbonyl group, a carboxyl group, an amide group and a hydroxyl group. When the reactive functional group (a) is an oxazoline group, the reactive functional group (b) may be a carboxyl group or a hydroxyl group. When the reactive functional group (a) is an alkoxysilyl group, the reactive functional group (b) may be an alkoxysilyl group.

The amide group mentioned here includes an alkylolamide group. Of course, the combination is not limited to the above combination, and a combination in which the reactive functional group (a) contained in the aqueous urethane resin (A) and the reactive functional group (b) present in the copolymer (B) are reactive. Anything can be used as long as it is.

Further, by introducing a hydrazide group as the reactive functional group (a) and a carbonyl group or an amide group as the reactive functional group (b) in these, low temperature stability, low temperature film-forming property, and resistance to film formation can be obtained. It is possible to improve the balance of blocking properties. The method for introducing the hydrazide group into the aqueous urethane resin is not particularly limited, but there is, for example, a method in which the aqueous urethane resin is produced by using a hydrazine derivative as a chain extender. Further, as a method for introducing a carbonyl group or an amide group into the acrylic copolymer aqueous dispersion, a method of copolymerizing a monomer having a carbonyl group or an amide group can be applied.

Further, both the aqueous urethane resin (A) and the copolymer (B) have a reactive functional group (c), and a crosslinking agent (reactive with the reactive functional group (c) ( By including d) in the coating agent, the effect of the present invention can be further enhanced. For example, a combination using a carboxyl group as the reactive functional group (c) and a polyfunctional epoxy crosslinking agent as the crosslinking agent (d), or a carbonyl group as the reactive functional group (c) and a polyfunctional hydrazide compound as the crosslinking agent (d). The combination etc. which are used are mentioned. In this case, of course, the combination is not limited to this.

According to the present invention, it is possible to provide an always dry water coating agent which has low-temperature film-forming properties even without containing a film-forming auxiliary, has good blocking resistance, and has good low-temperature stability.
Further, in the present invention, since the urethane resin is an essential component, the strength and elongation characteristics at low temperature, the adhesion to various substrates are also good, and it is also effective as a coating agent on elastic substrates. Please note.

[0064]

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The following "parts" and "%" are values based on weight.

[Aqueous Urethane Resin (A)] A-1: Hydran AP-60LM (manufactured by Dainippon Ink and Chemicals, Inc.) Carboxyl group-containing polyester-based aqueous urethane resin Nonvolatile matter: 42.0%, Tg value: 12 ℃, particle size:
180 nm

A-2: Hydran AP-70 (manufactured by Dainippon Ink and Chemicals, Inc.) Carboxyl group-containing polyester-based aqueous urethane resin Nonvolatile matter: 35.0%, Tg value: -4 ° C, Particle diameter:
190 nm

Production Example of Aqueous Urethane Resin (A-3) Polytetramethylene glycol (hydroxyl value = 56.1 m)
100 parts of gKOH / g) and 2 parts of 1,4-butanediol were added to 40 parts of methyl ethyl ketone and sufficiently dissolved with stirring, and 46 parts of isophorone diisocyanate was added and reacted at 80 ° C. for 3 hours. After cooling to 60 ° C, 9 parts of dimethylolpropionic acid and 65 parts of methyl ethyl ketone were added, 0.01 part of stannous octylate was added as a catalyst, and the reaction was carried out at 75 ° C. When the isocyanate value becomes 2.17% or less, the mixture is cooled to 40 ° C., and then 6.8 parts of triethylamine is added to the prepolymer for neutralization. Next, while stirring, 600 parts of water is added and mixed to emulsify and disperse.
46.6 parts of 0% piperazine aqueous solution <80 equivalent% as an amine group with respect to the remaining isocyanate groups> was added to carry out chain extension (increasing the molecular weight). The obtained emulsion was desolvated to obtain an aqueous dispersion having a nonvolatile content of 30%. Nonvolatile matter: 30.0%, Tg value: −73 ° C., particle size: 40 nm (triethylamine 1.6% contained in the aqueous dispersion)

[Production Example 1 B-1 Production Example of Copolymer (B)] St 80 parts, 2EHA 168 parts, MMA 1
A monomer mixture consisting of 44 parts and 10 parts of 80% AA was dispersed in an emulsifier aqueous solution obtained by dissolving 34 parts of Newcol 707SF (30% anionic emulsifier active ingredient manufactured by Nippon Emulsifier Co., Ltd.) in 80 parts of ion-exchanged water. A monomer emulsion was prepared. Further, 1.6 parts of sodium persulfate was dissolved in 32 parts of ion-exchanged water to prepare an initiator aqueous solution.

260 parts of ion-exchanged water was charged into a 1-liter reaction vessel equipped with a stirrer, a thermometer, and a condenser, and the temperature inside the reaction vessel was raised to 80 ° C. with stirring while feeding nitrogen gas. After the temperature was raised, the monomer emulsion and the aqueous initiator solution were dropped into the reaction vessel to carry out polymerization. The dropping time is 3 hours for both the monomer emulsion and the initiator aqueous solution,
The temperature inside the reaction vessel was maintained at 80 ° C. while stirring while dropping.
After maintaining the temperature at 80 ° C. with stirring for 30 minutes after the completion of dropping,
0.4 part of sodium persulfate was added to the reaction vessel, and the temperature was maintained at 80 ° C. with stirring for 2 hours. After cooling 10
The pH was adjusted with a% sodium hydroxide aqueous solution, adjusted water was added, and then taken out.

[Production Examples 2-5, B-2-5 Production Examples of Copolymer (B)] Production was carried out in the same manner as in Production Example 1 except that the raw materials were used according to Table 1.

[0071]

[Table 1]

[B-6 Comparative Production of Acrylic Copolymer] St 60 parts, 2EHA 208 parts, MMA 44
Part, and a monomer mixture consisting of 10 parts of 80% AA was dispersed in an emulsifier aqueous solution obtained by dissolving 26 parts of Newcol 707SF in 64 parts of ion-exchanged water to prepare a monomer emulsion (I). Also, St 2
A monomer emulsion (II) was prepared by dispersing a monomer mixture consisting of 0 part, 2EHA (30 parts) and MMA (30 parts) in an emulsifier aqueous solution prepared by dissolving 8 parts of Newcol 707SF in 16 parts of ion-exchanged water. Further, 1.6 parts of sodium persulfate was dissolved in 32 parts of ion-exchanged water to prepare an initiator aqueous solution.

260 parts of ion-exchanged water was charged into a 1-liter reaction vessel equipped with a stirrer, a thermometer, and a condenser, and the temperature inside the reaction vessel was raised to 80 ° C. with stirring while feeding nitrogen gas. After heating, the total amount of monomer emulsion (I),
And 80% of the aqueous initiator solution was dropped into the reaction vessel to carry out polymerization. The dropping time was 2 hours for both the monomer emulsion (I) and the aqueous initiator solution, and the inside of the reaction vessel was maintained at 80 ° C. while stirring while dropping. After the dropping was completed, the mixture was maintained at 80 ° C. for 2 hours while stirring, and then 20% of the monomer emulsion (II) and the aqueous solution of the initiator was started to be dropped into the reaction vessel, and the dropping was carried out for 1 hour. After completion of the dropping, the mixture was maintained at 80 ° C. for 30 minutes while stirring, then 0.4 part of sodium persulfate was added, and further maintained at 80 ° C. for 2 hours while stirring. After cooling, the pH was adjusted with a 15% sodium hydroxide aqueous solution, adjusted water was added, and then taken out. The obtained emulsion has the following properties.

Core emulsion glass transition temperature; 22 ° C. (calculated value) Shell emulsion glass transition temperature; −18 ° C. (calculated value) Nonvolatile matter; 50.1% Viscosity; 100 mPa · s PH; 8.1 MFT; 0 ° C. or lower

An aqueous resin dispersion (C) was obtained by mixing the aqueous urethane resin (A) and the copolymer (B) in the ratios shown in Tables 2-1 and 2-2.

[0076]

[Table 2]

[0077]

[Table 3]

[Production Example of Aqueous Resin Dispersion (C-8)] S
t 60 parts, 2EHA 124.5 parts, MMA 10
A monomer emulsion was prepared by dispersing a monomer mixture consisting of 3.5 parts, 7.5% of 80% AA and 6 parts of DAAM in an emulsifier aqueous solution obtained by dissolving 25 parts of Newcol 707SF in 60 parts of ion-exchanged water. Further, 1.2 parts of sodium persulfate was dissolved in 24 parts of ion-exchanged water to prepare an initiator aqueous solution.

With a stirrer, thermometer, and cooler attached
Aqueous urethane resin A-3 500 in a 2 liter reaction vessel
Part, Newcol 707SF 20 parts, ion-exchanged water 9
4 parts were charged, and the inside of the reaction vessel was heated to 80 ° C. with stirring while feeding nitrogen gas. After the temperature was raised, the monomer emulsion and the aqueous initiator solution were dropped into the reaction vessel to carry out polymerization. The dropping time was set to 3 hours for both the monomer emulsion and the initiator aqueous solution, and the inside of the reaction vessel was maintained at 80 ° C. while stirring during dropping. After the dropwise addition was completed, the mixture was kept at 80 ° C. for 30 minutes while stirring, then 0.4 part of sodium persulfate was put into the reaction vessel, and kept at 80 ° C. for 2 hours while stirring. After cooling, P with 15% sodium hydroxide solution
After adjusting H and adding adjusted water, it was taken out.

Nonvolatile content: 44.8%, viscosity: 69
0 mPa · s PH: 8.2, calculated Tg of copolymer (B): 15
℃

[Preparation of Permanent Dry Water Coating Agent 1, Examples 1 to 1]
9, Comparative Examples 1 to 5] A coating paste was prepared by dispersing the formulations shown in Table 3 below with a disper.

[0082]

[Table 4]

(* 1) Pigment dispersant manufactured by Kao Corporation (* 2) Antiseptic made by Dainippon Ink and Chemicals, Inc. (* 3) Tyca oxide titanium oxide (* 4) Defoamer manufactured by San Nopco Ltd.

The above aqueous resin dispersion (C), paste and the like were blended as shown in Tables 4-1 to 3 to prepare a coating material.

[0085]

[Table 5]

[0086]

[Table 6]

[0087]

[Table 7]

(* 5) Polyfunctional epoxy crosslinking agent manufactured by Dainippon Ink and Chemicals, Inc. (* 6) Thickener manufactured by UCC (* 7) Thickener manufactured by Asahi Denka Co., Ltd.

[Paint Test Result]

[0090]

[Table 8]

[0091]

[Table 9]

[Test Method] Low-temperature film-forming property: The coating material was applied to a flexible plate with a 6-mil applicator in a 5 ° C. atmosphere, and the film-forming state after drying at 5 ° C. for 24 hours was visually determined. A: A uniform coating film is formed without cracks. ○: Very small cracks are seen. Δ: Fine cracks are seen. X: A coating film is not formed and it becomes powdery.

Blocking resistance: The coating material was applied to a glass plate with a 6 mil applicator, dried at room temperature for 7 days, carbon paper was placed on the glass plate and left for 1 hour under a load of 1 kg. It was judged. A: Not transferred at all ◯: Very small amount is transferred. Δ: About 50% transferred. X: About 50% or more is transferred.

Low temperature stability: The coating is left at -5 ° C for 16 hours and then at room temperature for 8 hours. After repeating this cycle three times, the state of the paint was visually judged. ○: No problem △: Slightly thickened ×: Gelation

Solvent content: Qualitative / quantitative analysis was performed by GC-MS. (Wt% in coating agent) Paint viscosity: The paint viscosity of the prepared paint was measured with a Stormer viscometer. Gloss: A glass plate was coated with a 6 mil applicator, and 60-degree gloss was measured one day later.

Water resistance: A paint diluted with 75 KU was applied to a flexible plate by brushing (twice), dried at room temperature for 1 day, then flooded for half a day for 7 days, and after drying, the gloss of the flooded part and the non-flooded part was changed. It was measured and the gloss retention was calculated. ◯: Gloss retention 70% or more Δ: Gloss retention 50 to 69% X: Gloss retention less than 50%

[Preparation of Permanent Dry Water Coating Agent 2, Example 10
16, Comparative Examples 6 to 10] Compounding was performed according to Tables 7-1 and 2 below to prepare a coating agent.

[0098]

[Table 10]

[0099]

[Table 11]

(* 8) Wetting agent manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. (* 9) Thickener manufactured by Asahi Denka Co., Ltd. (* 10) Color pigments manufactured by Dainippon Ink and Chemicals, Inc. [Paint test results]

[0101]

[Table 12]

[0102]

[Table 13]

[Test Method] Low-temperature film-forming property: The coating material was applied to a flexible plate with a 6-mil applicator in a 5 ° C. atmosphere, and the film-forming state after drying at 5 ° C. for 24 hours was visually determined. A: A uniform coating film is formed without cracks. ○: Very small cracks are seen. Δ: Fine cracks are seen. X: A coating film is not formed and it becomes powdery.

Blocking resistance: The coating material was applied to a glass plate with a 6 mil applicator, dried at room temperature for 7 days, carbon paper was put on the glass plate, and the degree of transfer of carbon was visually observed after leaving it under a load of 500 g for 30 minutes. It was judged. ⊚: No transfer at all ○: Very little transferred Δ: About 50% transferred ×: About 50% or more transferred

Low temperature stability: The coating is left at -5 ° C for 16 hours and then at room temperature for 8 hours. After repeating this cycle three times, the state of the paint was visually judged. ○: No problem △: Slightly thickened ×: Gelation

Solvent content: Qualitative / quantitative analysis was performed by GC-MS. (Wt% in coating agent) Paint viscosity: The paint viscosity of the prepared paint was measured with a Stormer viscometer.

Water resistance: A flexible plate coated with a sealer in advance was brushed with a paint diluted to 75 KU.
After being dried for 1 day at room temperature, the half surface was immersed for 7 days, and after that, the state of blistering and peeling of the coating film was visually determined. ○: Almost no blistering or peeling. Δ: There is blistering. X: Peeling of the coating film can be observed.

[0108]

Industrial Applicability According to the present invention, it is possible to provide an always dry water-based coating composition which has low-temperature film-forming properties even without containing a film-forming auxiliary, has good blocking resistance and good low-temperature stability.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tokio Goto             776-10 Kamishiro-cho, Izumi City, Osaka Prefecture (72) Inventor Yoshihiro Okamoto             3-8-23 Gomonhigashi, Kumatori-cho, Sennan-gun, Osaka Prefecture F-term (reference) 4J038 CA021 CB011 CB081 CD081                       CE051 CG011 CG061 CG071                       CG141 CG161 CH031 CH041                       CH071 CR071 DG111 DG121                       DG131 DG191 DG271 DG281                       GA02 GA09 KA08 PA18

Claims (6)

[Claims] 1. A water-based urethane resin (A) and a copolymer (B) having a glass transition temperature of 5 ° C. or higher obtained by copolymerizing an ethylenically unsaturated monomer, and the solid content weight thereof. The ratio of (A) :( B) = 10: 90 to 90:10 is the aqueous resin dispersion (C) as an essential component, and the content of the volatile organic compound having a boiling point of 50 to 250 ° C. is the total amount of the coating agent. An ever-drying water-based coating agent, characterized in that the content is 1% by weight or less. 2. The normally dry aqueous coating material according to claim 1, wherein the glass transition temperature of the aqueous urethane resin (A) is 0 ° C. or lower. 3. The normally dry aqueous coating composition according to claim 1, which further comprises a pigment in an amount of 5 parts by weight or more and 200 parts by weight or less based on 100 parts by weight of the aqueous resin dispersion (C). 4. The aqueous urethane resin (A) has a reactive functional group (a), and the copolymer (B) has a reactive functional group (b) reactive with the reactive functional group (a). The always dry aqueous coating agent according to claim 1, 2 or 3, characterized in that it has. 5. A cross-linking agent (d) in which each of the aqueous urethane resin (A) and the copolymer (B) has a reactive functional group (c) and which is reactive with the reactive functional group (c). The always dry aqueous coating agent according to claim 1, 2 or 3, further comprising: 6. The normally dry aqueous coating composition according to claim 4, wherein the reactive functional group (a) is a hydrazide group, and the reactive functional group (b) is a carbonyl group and / or an amide group.