JPH06145278A - Production of aqueous dispersion of polyurethane - Google Patents

Abstract

PURPOSE:To provide an aqueous dispersion of a polyurethane having excellent storage stability and giving a coating film highly resistant to discoloration with heat. CONSTITUTION:The objective aqueous dispersion of a polyurethane is produced by polymerizing dimethylaminoethyl methacrylate in the presence of thioglycerol, reacting the obtained macromonomer containing tertiary nitrogen with a polycaprolactone diol having a molecular weight of 1,000, neopentyl glycol and a hydrogenated diphenylmethane diisocyanate in methyl ethyl ketone to effect the urethanization of the macromonomer, adding glacial acetic acid to neutralize the tertiary nitrogen atom in the polyurethane, emulsifying the product by dropping water thereto and distilling out the methyl ethyl ketone under reduced pressure. The aqueous dispersion of polyurethane produced by this process keeps high stability even after being left standing for 3 months and a coating film produced from the aqueous dispersion is resistant to discoloration even by heating in a dryer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a cationic aqueous polyurethane dispersion. More specifically, it relates to a method for producing an aqueous polyurethane dispersion using a special polyol component having a tertiary and / or quaternary nitrogen atom.

[0002]

2. Description of the Related Art A typical method for producing a conventional cationic polyurethane aqueous dispersion is, for example, an alkyl dialkanolamine such as N-ethyldiethanolamine,
A method is known in which other polyols are reacted with polyisocyanate as an essential component, and the tertiary nitrogen atom thereof is neutralized with an acid, or quaternized with an alkylating agent or the like to form a cation.

[0003]

However, the above-mentioned cationic polyurethane aqueous dispersion has the drawback that its stability over time is insufficient and that its coating is markedly colored by heat.

[0004]

The inventors of the present invention have made extensive studies on a method for producing a cationic polyurethane aqueous dispersion which gives a film having good storage stability and being hard to be colored by heat. When a polyol having a specific structure having a tertiary and / or quaternary nitrogen atom is used instead of a polyol such as N-methyldiethanolamine,
The inventors have found that the above problems can be solved and completed the present invention.

That is, the present invention provides a radically polymerizable unsaturated monomer having a tertiary and / or quaternary nitrogen atom in the presence of a mercaptan chain transfer agent having two or more hydroxyl groups and one mercapto group. Macromonomer (A) obtained by radical polymerization of the body and polyisocyanate (B)
The present invention provides a method for producing a polyurethane aqueous dispersion, which comprises reacting with as an essential component.

(Structure) The mercaptan chain transfer agent having two or more hydroxyl groups and one mercapto group used in the present invention (hereinafter, simply referred to as chain transfer agent) is as follows.
For example, 1-mercapto-1,1-methanediol, 1
-Mercapto-1,1-ethanediol, 3-mercapto-1,2-propanediol, 2-mercapto-1,
2-propanediol, 2-mercapto-2-methyl-
1,3-propanediol, 2-mercapto-2-ethyl-1,3-propanediol, 1-mercapto-2,
2-Propanediol, 2-mercaptoethyl-2-methyl-1,3-propanediol, 2-mercaptoethyl-2-ethyl-1,3-propanediol and the like can be mentioned.

The radically polymerizable unsaturated monomer containing a tertiary and / or quaternary nitrogen atom used in the present invention is, for example, dimethylaminomethyl (meth) acrylate or dimethylaminoethyl (meth). Acrylate,
Dimethylaminopropyl (meth) acrylate, diethylaminomethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, diethylaminopropyl (meth) acrylate, dimethylallylamine, dimethyldiallylammonium chloride, acryloylpyrrolidine and these monomers and hydrochloric acid, sulfuric acid, Inorganic acids such as nitric acid; organic acids such as formic acid, acetic acid, propionic acid; methyl chloride, methyl bromide, dimethyl sulfate, diethyl sulfate, benzyl chloride, p-nitrobenzyl chloride, benzyl bromide, ethylene chlorohydrin, ethylene bromine Examples thereof include quaternary nitrogen atom-containing monomers obtained by reacting a quaternizing agent such as hydrin, epichlorohydrin and brombutane.
These monomers may be used alone or in combination.

In some cases, it is possible to copolymerize with the following monomers. Examples of those are:
Alkyl (meth) acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, styrene, vinyl acetate, glycidyl (meth) acrylate, aryl glycidyl Glycidyl group-containing monomer such as ether, methacryloyloxyethyl acid phosphate, phosphoric acid group-containing monomer such as methacryloyloxypropyl acid phosphate and its ester or salt,
Sulfonic acid group-containing monomers such as styrene sulfonic acid and salts thereof, amide group-containing monomers such as (meth) acrylamide, perfluorooctylethyl (meth) acrylate, N-methyl (propyl) perfluorooctylsulfone Perfluoroalkyl group-containing monomers such as amidoethyl (meth) acrylate, polysiloxane group-containing monomers such as polydimethylsiloxylpropyl methacrylate, methoxypolyethylene glycol (meth)
Examples thereof include polyoxyethylene group-containing monomers such as acrylate.

As the method for producing the tertiary and / or quaternary nitrogen atom-containing macromonomer of the present invention, a conventionally known method can be applied, for example, in the presence of the chain transfer agent,
Radical polymerization of a radically polymerizable unsaturated monomer containing the tertiary and / or quaternary nitrogen atom-containing radically polymerizable unsaturated monomer as an essential component, if necessary using a polymerization catalyst. You can easily get it.

Examples of the polymerization catalyst include acyl peroxides such as benzoyl peroxide, tertiary butyl hydroperoxide, alkyl hydroperoxides such as p-methane hydroperoxide, di-tertiary butyl peroxide and the like. Examples thereof include peroxide compounds such as dialkyl peroxides and azobisisobutyronitrile compounds.

The amount of the above-mentioned tertiary and / or quaternary nitrogen atom-containing macromonomer (A) used for obtaining the polyurethane aqueous dispersion of the present invention is sufficient to obtain a stable aqueous dispersion. The solid content of the polyurethane resin is 1
The content of tertiary and / or quaternary nitrogen atoms per 100 parts by weight is at least 0.01 equivalent or more, preferably 0.0
It is necessary to be 2 to 0.2 equivalents.

Examples of the polyisocyanate (B) used in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate and 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.

Other active hydrogen-containing compounds capable of reacting with isocyanate groups used in the preparation of the polyurethane aqueous dispersion of the present invention are, for convenience, an average molecular weight of 300 to 1
It is divided into high molecular weight compounds of preferably 500 to 5,000 and low molecular weight compounds of 300 or less.

Examples of the high molecular weight compound include polyester polyol, polyether polyol, polycarbonate polyol, polyacetal polyol,
Examples thereof include polyacrylate polyol, polyester amide polyol, polythioether polyol and the like.

As the polyester polyol, for example, 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,
Glycol components such as hydrogenated bisphenol A, hydroquinone and their alkylene oxide adducts, and 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) ) Polyesters obtained by a ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone, in addition to polyesters obtained by a dehydration condensation reaction from an acid component such as benzoic acid and an ester-forming derivative of these hydryloxycarboxylic acids, and the like. The copolymerized polyester of

Examples of the polyether include 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, butyric acid with one or more compounds having at least two active hydrogen atoms such as 3-propanetrithiol as an initiator. Emissions oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, cyclohexylene, include those addition polymerization in a conventional manner one or more monomers and the like.

Examples of the polycarbonate polyol include compounds obtained by reacting glycols such as 1,4-butanediol, 1,6-hexanediol and diethylene glycol with diphenyl carbonate and phosgene.

The above low molecular weight compound has a molecular weight of 30.
A compound containing at least two active hydrogens in the molecule of 0 or less, for example, a glycol component used as a raw material for polyester polyol; a polyhydroxy compound such as glycerin, trimethylolethane, trimethylolpropane, sorbitol, pentaerythritol, and the like; Ethylenediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4′-dicyclohexylmethanediamine, 3,
3'-dimethyl-4,4'-dicyclohexylmethanediamine, 1,4-cyclohexanediamine, 1,2-propanediamine, hydrazine, diethylenetriamine,
Examples include amine compounds such as triethylenetetramine.

The method for producing the polyurethane aqueous dispersion of the present invention may be any of the methods well known in the art, and examples thereof include the following methods.

If necessary, a neutralizing agent is added to the organic solvent solution or organic solvent dispersion of the polyurethane resin obtained by reacting the macromonomer (A) and other active hydrogen-containing compounds with the polyisocyanate (B). A method of obtaining an aqueous dispersion by mixing an aqueous solution containing the same.

The terminal isocyanate group-containing urethane prepolymer obtained by reacting the macromonomer (A) and other active hydrogen-containing compound with the polyisocyanate (B) is mixed with an aqueous solution containing a neutralizing agent if necessary. Or a method in which a neutralizing agent is added to the prepolymer in advance, water is mixed and dispersed in water, and then the mixture is reacted with polyamine to obtain an aqueous dispersion.

An aqueous solution containing a polyamine and, if necessary, a neutralizing agent, in a urethane prepolymer containing a terminal isocyanate group obtained by reacting a macromonomer (A) and another active hydrogen-containing compound with a polyisocyanate (B). Or a neutralizing agent is added to the prepolymer in advance, if necessary, and then mixed with an aqueous solution containing a polyamine to obtain an aqueous dispersion.

The polyurethane resin and the urethane prepolymer containing a terminal isocyanate group according to the present invention are produced by a conventionally known method. For example, the polyisocyanate and the active hydrogen-containing compound (including the macromonomer (A)) are also included.
In the case of polyurethane resin, the equivalent ratio of isocyanate group and active hydrogen group is 0.8: 1 to 1.2: 1, preferably 0.9: 1 to 1.1: 1, and the terminal isocyanate In the case of a group-containing urethane prepolymer,
The reaction is carried out at a ratio of 1.1: 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 without 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.

When such an organic solvent is distilled off from the finally obtained polyurethane resin aqueous dispersion, it is preferable to use one 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.

In the methods (1) to (3), in addition to the macromonomer (A) of the present invention, a hydrophilic atomic group used in a conventional method for producing an aqueous polyurethane dispersion or an atomic group capable of becoming hydrophilic by neutralization is included. Moreover, an active hydrogen-containing compound capable of reacting with an isocyanate group may be used in combination.

Examples of such compounds include 2-oxyethanesulfonic acid, phenolsulfonic acid, sulfobenzoic acid, sulfosuccinic acid, 5-sulfoisophthalic acid, sulfanilic acid, 1,3-phenylenediamine-4,6-.
A sulfonic acid-containing compound such as disulfonic acid or 2,4-diaminotoluene-5-sulfonic acid, a derivative thereof, or a polyester polyol obtained by copolymerizing these compounds;
Carboxylic acid-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, dioxymaleic acid, 2,6-dioxybenzoic acid and 3,4-diaminobenzoic acid And derivatives thereof or polyester polyols obtained by copolymerizing these; methyldiethanolamine, ethyldiethanolamine, propyldiethanolamine, butyldiethanolamine, oleyldiethanolamine, N, N-dioxyethylaniline, N, N-dioxyethyltoluidine, alkyl 3 such as diisopropanolamine, allyldiisopropanolamine, dioxyethylpiperazine
A compound containing a tertiary amino group and a derivative thereof, or a polyester polyol or a polyether polyol obtained by copolymerizing the same; a polyester polyol or a polyether obtained by copolymerizing the compound containing a tertiary amino group and a derivative thereof or these Polyol, methyl chloride, methyl bromide, dimethylsulfate, diethylsulfate,
Reactants of quaternizing agents such as benzyl chloride, p-nitrobenzyl chloride, benzyl bromide, ethylene chlorohydrin, ethylene bromohydrin, epichlorohydrin, brombutane; polymers containing at least 30% by weight of ethylene oxide repeating units Molecular weight 300-10,000 containing at least one or more active hydrogen
Nonionic group-containing compounds such as polyoxyethylene-polyoxyalkylene copolymer or polyester polyether polyol obtained by copolymerizing these,
These may be used alone or in combination.

In the method of the present invention, an emulsifier may be used in combination, if necessary. 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.

Examples of the neutralizing agent for neutralizing the tertiary and / or quaternary nitrogen atoms which can be used in the production of the polyurethane aqueous dispersion of the present invention include inorganic substances such as hydrochloric acid, sulfuric acid and nitric acid. Acids; organic acids such as formic acid, acetic acid, propionic acid, etc .; methyl chloride, methyl bromide, dimethyl sulfate, diethyl sulfate, benzyl chloride, p-nitrobenzyl chloride, benzyl bromide, ethylene chlorohydrin, ethylene bromohydrin, epichlorohydrin , Brombutane and the like, and the time of neutralization may be before, during or after the polymerization of the tertiary nitrogen atom-containing unsaturated monomer, or during or after the urethanization reaction. .

Examples of the polyamine which can be used in the production of the aqueous polyurethane dispersion of the present invention include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2-methylpiperazine and 2,5-. Dimethylpiperazine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, 3,
3'-dimethyl-4,4'-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, aminopropylethanolamine, aminohexylethanolamine, aminoethylpropanolamine,
Examples thereof include diamines such as aminopropylpropanolamine and aminohexylpropanolamine; polyamines such as diethylenetriamine, dipropylenetriamine and triethylenetetramine; hydrazines; acid hydrazides, which may be used alone or in combination.

The polyurethane resin aqueous dispersion thus obtained may be used as it is, but it is also possible to distill away the organic solvent as necessary and use it as a polyurethane resin aqueous dispersion.

Various kinds of distillation apparatuses can be used for removing the organic solvent by distillation, but a distillation apparatus which does not release the organic solvent after the distillation efficiency and the distilled solvent is preferable, and a thin-film evaporation apparatus is particularly preferable.

In the above-mentioned methods 1 to 3 for producing the aqueous dispersion of the present invention, if necessary, in addition to water, other aqueous dispersions or aqueous dispersions such as vinyl acetate-based, ethylene vinyl acetate-based,
Acrylic, acrylic styrene, etc. emulsions; styrene / butadiene, acrylonitrile / butadiene, acrylic / butadiene, etc. latex; polyethylene, polyolefin, etc. ionomers; polyurethane, polyester, polyamide, epoxy resins, etc. You may use a dispersion and an aqueous dispersion together.

The polyurethane resin aqueous dispersion thus obtained by removing the organic solvent is a substantially solvent-free aqueous dispersion having a solid content of about 10 to 60% by weight, preferably 15 to 50% by weight. However, even if it is unavoidable that an organic solvent having a boiling point of 100 ° C. or higher has to be used for the production of the polyurethane resin aqueous dispersion, the amount of such an organic solvent used should be limited to 20% by weight based on the total weight of the aqueous dispersion. Should be.

The synthetic resin aqueous dispersion obtained by the method of the present invention may be used as it is, or may be another aqueous dispersion such as a vinyl acetate type, ethylene vinyl acetate type, an acrylic type, an acrylic styrene type emulsion; styrene. It can be used by blending with latex of butadiene type, acrylonitrile / butadiene type, acrylic / butadiene type, etc .; ionomer of polyethylene type, polyolefin type, etc .; water dispersion of polyurethane, polyester, polyamide, epoxy type in any proportion. .

Further, fillers such as carbon black, clay, talc and aluminum hydroxide; additives such as silica sol, alumina sol, plasticizer and pigments; alkylene glycol derivatives or film-forming aids such as dialkyl esters of aliphatic dicarboxylic acids. Agents: Fluorine-based or dialkylsulfosuccinate-based emulsifiers, various leveling agents such as acetylene glycol derivatives; Mineral oil-based, Amide-based
Various antifoaming agents such as silicone-based agents or a small amount of alcohols such as ethanol and isopropyl alcohol can be added.

Further, for the purpose of improving various durability such as light resistance, heat resistance, water resistance, solvent resistance, heat resistance and the like of the above water dispersion, stabilizers such as antioxidants, ultraviolet absorbers, hydrolysis inhibitors and the like. Is added during or after the production process of the polyurethane aqueous dispersion, or also epoxy resin, melamine resin,
A crosslinking agent such as an isocyanate compound, an aziridine compound, or a polycarbodiimide compound may be blended and used.

Tertiary and / or obtainable by the process of the invention
Alternatively, the quaternary nitrogen atom-containing macromonomer not only has a reaction-promoting effect in the urethanization reaction, but can also be stably introduced without problems such as gelation. It is easy to introduce a quaternary nitrogen atom.

The polyurethane aqueous dispersion of the present invention thus obtained has a good film-forming property and is capable of forming a transparent and uniform film, and has good adhesion to various substrates, water resistance, and Excellent solvent resistance, polyester, nylon,
Various plastics such as PVC, metal, glass, paper, textiles,
It is useful as an adhesive, a binder, a sizing agent, a paint, a surface treatment agent, a coating agent, an aqueous gravure ink, etc. for a substrate such as leather or wood.

[0040]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto. In the present invention, parts and% are based on weight unless otherwise specified.

Production Example 1 4 equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen inlet tube
In a two-necked flask, 172 parts of methyl ethyl ketone, 200 parts of dimethylaminoethyl methacrylate, 10 parts of thioglycerin and 1 part of a catalyst were charged and polymerized at 80 ° C. for 8 hours,
Hydroxyl value 26.7, amine value 187.1, solid content concentration 5
5% of tertiary nitrogen-containing macromonomer A was obtained.

Example 1 Polycaprolactone diol having a molecular weight of 1,000 1097.
2 parts, tertiary nitrogen-containing macromonomer A288.4 parts,
Neopentyl glycol 144 parts, dismodular W
[Sumitomo Bayer Ltd. hydrogenated diphenylmethane diisocyanate] 524 parts, dibutyltin dilaurate 0.
4 parts and 1445 parts of methyl ethyl ketone are mixed to obtain 75 ° C.
After reacting at 20 ° C. for urethanization, glacial acetic acid 5
8 parts was added to neutralize the tertiary nitrogen atom in the polyurethane, 4490 parts of water was gradually added dropwise with stirring to emulsify, and further methyl ethyl ketone was distilled off under reduced pressure to remove a polyurethane aqueous solution having a solid content of 30%. A dispersion was obtained. This polyurethane aqueous dispersion was extremely stable even after standing for 3 months. The film obtained from this aqueous dispersion did not become colored even when heated in a dryer.

COMPARATIVE EXAMPLE 1 Instead of the macromonomer A of Example 1, N-methyldiethanolamine was added to the macromonomer A having a tertiary nitrogen content.
In the same manner as in Example 1 except that the same amount as
A cationic polyurethane aqueous dispersion was synthesized. Specifically, the following operation was performed.

1242 parts of polycaprolactone diol having a molecular weight of 1,000, N-methyldiethanolamine 114.
4 parts, neopentyl glycol 43.2 parts, dismodul W524 parts, dibutyltin dilaurate 0.4
And 1574 parts of methyl ethyl ketone were mixed and reacted at 75 ° C. for 20 hours to form a urethane, and then glacial acetic acid 58
Was added to neutralize the tertiary nitrogen atom derived from N-methyldiethanolamine in the molecule, and 4490 parts of water was gradually added dropwise with stirring to emulsify, but a stable aqueous dispersion was not obtained. It was

Example 2 Instead of neutralizing the methyl ethyl ketone solution of the polyurethane resin obtained in Example 1 with glacial acetic acid, methyl iodide was added for quaternization, and then water was added dropwise to emulsify the solution. Further, methyl ethyl ketone was distilled off under reduced pressure to obtain a solid content of 30%.
A cationic polyurethane aqueous dispersion was obtained. This polyurethane aqueous dispersion was extremely stable even after standing for 3 months. The film obtained from this aqueous dispersion did not become colored even when heated in a dryer.

Example 3 Polytetramethylene glycol with a molecular weight of 1,000 939.
6 parts, tertiary nitrogen-containing macromonomer A 709.2 parts,
866 parts of isophorone diisocyanate, 170 parts of 1,4-butanediol and 1260 parts of methyl ethyl ketone were mixed and reacted at 70 ° C. for 6 hours to synthesize an isocyanate group-terminated prepolymer, and then dimethyl sulfate 298
Was added to quaternize the tertiary nitrogen atom in the prepolymer, and 8000 parts of water was added while stirring at high speed with a homomixer to prepare an aqueous dispersion of the prepolymer, and further 70 parts of anhydrous piperazine was dissolved. 350 parts of an aqueous solution was added dropwise over about 1 minute, and then methyl ethyl ketone was distilled off under reduced pressure to obtain a polyurethane aqueous dispersion having a solid content concentration of 25%. This polyurethane aqueous dispersion was extremely stable even after standing for 3 months. The film obtained from this aqueous dispersion did not become colored even when heated in a dryer.

Example 4 Polyester diol having a molecular weight of 2,000 (neopentyl glycol / 1,6-hexanediol / adipic acid) 8
62.8 parts, tertiary nitrogen-containing macromonomer A370.
8 parts, 1,4-butanediol 133.2 parts, tolylene diisocyanate 348 parts, methyl ethyl ketone 865
Parts were mixed and reacted at 75 ° C. for 12 hours to form a urethane, then 74.2 parts of glacial acetic acid was added to neutralize the tertiary nitrogen atom in the polyurethane, and 3620 parts of water was gradually added dropwise with stirring. The mixture was emulsified, and methyl ethyl ketone was distilled off under reduced pressure to obtain a cationic polyurethane aqueous dispersion having a solid content concentration of 30%. This polyurethane aqueous dispersion has 3
It was extremely stable even after left for a month. The film obtained from this aqueous dispersion did not become colored even when heated in a dryer.

The polyurethane aqueous dispersions obtained by the production methods of the examples of the present invention were all very excellent in the dispersibility of various fillers.

[0049]

According to the method of the present invention, the third group as a hydrophilic group is used.
Since a tertiary and / or quaternary nitrogen atom can be introduced into the graft chain at an arbitrary molecular weight, the hydrophilic group can be localized,
A polyurethane aqueous dispersion having good dispersibility in water can be easily obtained even if the hydrophilic group content is smaller than in the conventional method. The aqueous dispersion obtained at the same time has extremely good stability over time and mechanical stability.

Since a hydrophilic group is present in the side chain, various inorganic,
Good dispersibility of organic pigments or various fillers,
Further, there is an advantage that the main chain of the polyurethane resin is relatively resistant to hydrolysis and deterioration, is excellent in hydrolysis resistance, and is also resistant to coloration by heat.

Claims (1)

[Claims] 1. A radical-polymerizable unsaturated monomer containing a tertiary and / or quaternary nitrogen atom is radicalized in the presence of a mercaptan chain transfer agent having two or more hydroxyl groups and one mercapto group. A method for producing a polyurethane aqueous dispersion, which comprises reacting a macromonomer (A) obtained by polymerization with a polyisocyanate (B) as an essential component.