JPH05320361A - Production of aqueous dispersion of polyurethane resin having high solid content - Google Patents

Abstract

PURPOSE:To provide an aqueous dispersion of a polyurethane resin having high solid content and excellent aging stability. CONSTITUTION:An aqueous dispersion of a polyurethane resin having high solid content is produced by dissolving an isocyanate-terminated prepolymer containing hydrophilic group in a hydrophobic organic solvent, emulsifying and dispersing the prepolymer under mechanical shearing force to extend the chain and subsequently removing the solvent under reduced pressure. An aqueous dispersion of polyurethane resin particles having uniform and large particle diameter can be produced by this process and the dispersion has extremely excellent long-term aging stability and mechanical stability. An aqueous adhesive of a polyurethane resin having high solid content and excellent dryability and initial bond strength can be produced from the dispersion.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aqueous dispersion of a high solid content polyurethane resin. More specifically, it relates to a method for producing a polyurethane resin aqueous dispersion having a solid content of more than 50% by weight and excellent storage stability.

[0002]

As a conventional method for producing an aqueous dispersion of a polyurethane resin, a hydrophilic group-containing isocyanate-terminated prepolymer dissolved in a hydrophilic organic solvent such as N-methylpyrrolidone, methyl ethyl ketone, or acetone is used, if necessary. Either neutralize with a neutralizing agent and then mix with water, or if necessary, mix with water containing a neutralizing agent and once disperse in an aqueous medium and then react with a chain extender, or chain extender There is known a method in which a chain extension reaction is carried out simultaneously with the dispersion in an aqueous medium by mixing with a water containing an agent and optionally a neutralizing agent.

[0003]

However, in the above-mentioned method, since the hydrophilic organic solvent is used for the purpose of assisting the dispersion in water, the dispersion of the polyurethane resin in the aqueous medium is extremely good, and the obtained resin is obtained. The particle size of the aqueous polyurethane dispersion is extremely small, usually about 0.5 μm or less. Therefore, in the conventional manufacturing method, at most 50% by weight
It has a drawback that only a polyurethane aqueous dispersion having a solid content of about a certain degree can be obtained.

Polyurethane aqueous dispersions are used in many applications in place of conventional organic solvent-based polyurethane resins because they do not contain harmful and fire-safe organic solvents, but are common to aqueous dispersions. However, there is a problem that the drying property is slow, and particularly when the conventional low solid content aqueous dispersion is used as an adhesive, the drying property is slow and the initial adhesive property is remarkably poor.

Therefore, the present inventors have conducted intensive studies on a method for producing an aqueous dispersion of a polyurethane resin having a high solid content and excellent stability over time, and as a result, completed the present invention.

[0006]

According to the present invention, (1) a solution of a hydrophilic group-containing isocyanate-terminated prepolymer in a hydrophobic organic solvent is mixed with water optionally containing a neutralizing agent under mechanical shearing force. After mixing and dispersing in an aqueous medium, it is reacted with a chain extender or a solution of a hydrophilic group-containing isocyanate-terminated prepolymer in a hydrophobic organic solvent contains a chain extender and, if necessary, a neutralizing agent. A high solid content polyurethane resin aqueous dispersion characterized in that water is mixed under mechanical shearing force to carry out chain extension reaction and dispersion in an aqueous medium at the same time, and then (2) desolvation is carried out under reduced pressure. A manufacturing method is provided. (Structure) In the present invention, the “shearing force” is a force exerted by the object portions on both sides of an arbitrary unit area taken inside the object, and two orthogonal reference lines are formed in the object. It is concretely expressed as the stress (SHEAR STRENGTH) that occurs when a deformation (shear) occurs such that the angle formed by these lines is displaced from a right angle when pulled. "Mechanical" means that a work is performed by a mechanical device driven by power (in the case of the present invention,
A job is "mixing." ).

"Mixing under mechanical shear" means that when two orthogonal reference lines are drawn in the mixed fluid,
Mixing is performed by a mechanical device that moves by power so that stress deformation (shearing) such that the angle formed by these lines deviates from a right angle due to deformation.

The "water containing a neutralizing agent as necessary" includes two forms, that is, a form of only water and a form of a mixture of the neutralizing agent and water, and water is an essential component of the present invention. It is a constituent. "Water containing a chain extender and optionally a neutralizing agent"
The chain extender and water are essential constituents, and includes two forms, a form consisting of the chain extender and water alone, and a form consisting of the chain extender, water and a neutralizing agent. . It should be noted that the word "as needed" never extends to "water".

In the present invention, the "hydrophilic group" includes both a functional group which is hydrophilic by itself and a functional group which can be converted into a hydrophilic group by neutralization as described later. Examples of the polyisocyanate used in the production of the hydrophilic group-containing isocyanate-terminated prepolymer according to the present invention include 2,4-tolylene diisocyanate and 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, tetramethylxylyl Examples thereof include diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and 3,3′-dimethyl-4,4′-dicyclohexylmethane diisocyanate.

Examples of the raw material used for introducing the hydrophilic group of the isocyanate-terminated prepolymer having a hydrophilic group of the present invention include, for example, at least one active hydrogen atom in the molecule, and a carboxylic acid Basically ionic compounds containing at least one functional group selected from the group consisting of salts, salts of sulfonic acids, quaternary amino groups, carboxylic acid groups, sulfonic acid groups and tertiary amino groups are preferred. In addition to this, a nonionic group having at least one active hydrogen atom in the molecule and containing a group consisting of ethylene oxide repeating units and a group consisting of ethylene oxide repeating units and other alkylene oxide repeating units You may use together the compound of.

Examples of the hydrophilic group-containing compound include 2-oxyethanesulfonic acid, phenolsulfonic acid,
Sulfobenzoic acid, sulfosuccinic acid, 5-sulfoisophthalic acid, sulfanilic acid, 1,3-phenylenediamine-
4,6-disulfonic acid, 2,4-diaminotoluene-5
-Sulfonic acid-containing compounds such as sulfonic acid and derivatives thereof or polyester polyols obtained by copolymerizing these; 2,2-dimethylolpropionic acid, 2,2-
Dimethylol butyric acid, 2,2-dimethylol valeric acid, dioxymaleic acid, 2,6-dioxybenzoic acid, 3,4-
Carboxylic acid-containing compounds such as diaminobenzoic acid and derivatives thereof or polyester polyols obtained by copolymerizing these; methyldiethanolamine, ethyldiethanolamine, propyldiethanolamine, butyldiethanolamine, oleyldiethanolamine, N,
Tertiary amino group-containing compounds such as N-dioxyethylaniline, N, N-dioxyethyltoluidine, alkyldiisopropanolamine, allyldiisopropanolamine and dioxyethylpiperazine, and their derivatives or copolymers thereof Polyester polyol or polyether polyol; Polyester polyol or polyether polyol obtained by copolymerizing the above-mentioned tertiary amino group-containing compound and derivatives thereof, and methyl chloride, methyl bromide, dimethylsulfate, diethylsulfate, chloride Reactants of quaternizing agents such as benzyl, p-nitrobenzyl chloride, benzyl bromide, ethylene chlorohydrin, ethylene bromhydrin, epichlorohydrin, brombutane; at least 30-fold ethylene oxide repeating units % By weight or more, a molecular weight from 300 to 2 containing at least one or more active hydrogen in the polymer
10,000 polyoxyethylene glycols or polyoxyethylene-polyoxypropylene copolymer glycols, polyoxyethylene-polyoxybutylene copolymer glycols, polyoxyethylene-polyoxyalkylene copolymer glycols or monoalkyl ethers thereof, etc. And the polyester polyether polyols obtained by copolymerizing these, and these are used alone or in combination.

When the hydrophilic group-containing isocyanate-terminated prepolymer used in the present invention is produced, the content of the hydrophilic group bonded in the molecule is such that the hydrophilic group is a carboxyl group, a sulfonic acid group, a sulfonate group, In the case of an ionic group such as a tertiary amino group or a quaternary amino group,
At least 0.001 to 0.1 equivalent, preferably 0.1 to 100 parts by weight of the solid content of the polyurethane resin finally obtained.
002 to 0.05 equivalent is required. In particular, as the hydrophilic group, anionic hydrophilic groups such as a carboxyl group, a sulfonic acid group, and a sulfonate group are preferable.

When a nonionic compound is used,
If the amount used is too large, the viscosity of the finally obtained aqueous dispersion becomes high, so at least 10 parts by weight or less, preferably 5 parts by weight or less per 100 parts by weight of the solid content of the polyurethane resin finally obtained. is necessary.

The other active hydrogen-containing compound capable of reacting with the isocyanate group used in the production of the hydrophilic group-containing isocyanate-terminated prepolymer of the present invention is, for convenience, an average molecular weight of 300 to 10,000, preferably 500 to 10,000.
It is divided into high molecular weight compounds of 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, 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 Acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4
Of naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane-p, p′-dicarboxylic acid and these dicarboxylic acids Anhydrides or ester-forming derivatives; polyesters obtained by dehydration condensation reaction with acid components such as p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid and ester-forming derivatives of these hydoxycarboxylic acids Other examples include polyesters obtained by a ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone and copolymerized polyesters thereof.

As the polyether, 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, hydroxy Ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin with one or more compounds having at least two active hydrogen atoms such as phthalic acid, 1,2,3-propanetrithiol and the like as an initiator. Examples thereof include those obtained by addition-polymerizing one or more monomers such as tetrahydrofuran and cyclohexylene 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.

The 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 hydrophilic group-containing isocyanate-terminated prepolymer of the present invention is, for example, a compound produced from the above-mentioned compound containing a hydrophilic group, other active hydrogen-containing compound and polyisocyanate, and produced by a conventionally known method. Any of them can be used as long as they are, for example, the polyisocyanate, the compound containing a hydrophilic group, and the other active hydrogen-containing compound, the equivalent ratio of the isocyanate group and the active hydrogen group is 1.1: 1 to 3: 1. , Preferably 1.2: 1
20 to 120 ° C., preferably 30 to 1 at a ratio of 2: 1
Examples include those reacted at 00 ° C.

These reactions can be carried out either without solvent or in the presence of an organic solvent. In order to achieve high solidification, the hydrophilic group-containing isocyanate terminated prepolymer of the present invention is finally added. It is necessary to disperse in water as a solution of a hydrophobic organic solvent. By using a hydrophobic organic solvent, while maintaining the stability of the aqueous dispersion over time, which was difficult when using a conventional hydrophilic organic solvent, to make the particle diameter of the aqueous dispersion uniform and large. This enabled high solidification for the first time. Examples of the hydrophobic organic solvent include basic hydrocarbons having a solubility of 1 part or less in 100 parts of water such as aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic hydrocarbons such as heptane, hexane and cyclohexane. Examples include hydrophobic organic solvents. It is necessary that the amount of the hydrophobic organic solvent used is at least 1 part or more, preferably 2 to 100 parts, based on 100 parts of the solid content of the hydrophilic group-containing isocyanate-terminated prepolymer.

Further, a conventional hydrophilic organic solvent may be partially used in combination within the range of not inhibiting the high solidification of the present invention. As such a hydrophilic organic solvent, for example,
Ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; acetic acid esters such as ethyl acetate and butyl acetate; amides such as dimethylformamide and N-methylpyrrolidone.

Since 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 unavoidable that an organic solvent having a boiling point of 100 ° C. or higher must be used, it is preferable to keep the amount used to the minimum necessary.

In the present invention, a solution of the hydrophilic group-containing isocyanate-terminated prepolymer as described above in a hydrophobic organic solvent is neutralized with water containing a neutralizing agent if necessary, or with a chain extender and, if necessary, neutralized. Water containing the agent is mixed under mechanical shearing force to disperse it in an aqueous medium, or simultaneously perform chain extension reaction and dispersion in an aqueous medium.

The magnitude of the mechanical shearing force can be expressed by the number of powers per cubic meter per hour, and usually it can be arbitrarily selected within the range of 0.05 to 100 kw / m ³ · hr ^−1. However, since it depends on the type of mixer described later, it is preferable to determine the conditions appropriately using an actual mixer.

Examples of the mixer used when mixing the prepolymer hydrophobic organic solvent solution and water under mechanical shear include, for example, a line mill, a rotor-stator mixer, a harell homogenizer, a microfluidizer and others Engineering Handbook, 779-782
Page (1989) ”, a mixer for generating a shearing force, such as a high-speed rotating pipe-in mixer, an internal circulation type continuous stirrer in-line mixer, a pressure nozzle type emulsifier, an ultrasonic emulsifier, etc. is preferable. Mixing in a batch having a strong stirring mixer is also acceptable.

Specific mixers include, for example, Hareru Homogenizer manufactured by Domestic Seiko Co., Ltd., Pipeline Homo Mixer manufactured by Tokushu Kika Kogyo Co., Ltd., Milder manufactured by Ebara Corporation, Supraton manufactured by Tsukishima Kikai Co., Ltd. , Microfluidizer, Doton Shoji Co., Ltd. Manton Gorin, and the like.

The specific magnitude of mechanical shearing force is, for example, 15 in the case of Harel homogenizer manufactured by Domestic Seiko Co., Ltd.
˜50 kw / m ³ · hr ⁻¹ , 0.2 to ³⁰ kw / m ^{3 in} the case of pipeline homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.
・ Hr ^-1 and 2. in case of Milder made by EBARA CORPORATION.
5-40 kw / m ³ · hr ^-1 , 1.25-40 kw / m ³ · hr ^-1 for Tsukishima Kikai Co., Ltd., 10 for Tsukishima Kikai Microfluidizer
100 kW / m ³ · hr ^-1 , ^{3 to} 50 kW / m ³ · hr in the case of Goei Co., Ltd.'s Gorin and homogenizer
It is preferably ^-1 .

As described above, in the case where the hydrophilic group-containing isocyanate-terminated prepolymer is an isocyanate-terminated prepolymer containing a functional group capable of becoming a hydrophilic group by neutralization, it is necessary to neutralize the functional group. Soap agents are used.

The neutralizing agent that can be used in the present invention is not particularly limited as long as it can neutralize or ionize the above hydrophilic group-containing compound. For example, non-volatile agents such as sodium hydroxide and potassium hydroxide. Base; tertiary amines such as trimethylamine and triethylamine, and volatile bases such as ammonia are mentioned, and volatile bases are particularly preferable. The time of neutralization or ionization with these neutralizing agents may be before, during, or after the production of the hydrophilic group-containing isocyanate-terminated prepolymer, or may be present in the water used for dispersion. Absent. Further, the amount of the neutralizing agent used is such that neutralizing agent / acid group =
The range of 0.5 / 1 to 1/1 is preferable.

In the method of the present invention, an emulsifier may be used in combination. Examples of such an emulsifier include polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrenated phenyl ether and polyoxyethylene sorbitol tetraole. Nonionic emulsifiers such as ates; fatty acid salts such as sodium oleate, alkyl sulfate ester salts, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, sodium alkane sulfonates, sodium alkyl diphenyl ether sulfonates, etc. Anionic emulsifiers: nonionic anionic emulsifiers such as polyoxyethylene alkylphenyl sulfate and polyoxyethylene alkyl sulfate. Among these, anionic or nonionic anionic emulsifiers are preferable because they are excellent in the effect of lowering the viscosity when highly solidified. The amount of the emulsifier to be added needs to be within a range that does not adversely affect the adhesiveness of various kinds of finally obtained polyurethane resin to various substrates, water resistance, etc., and is 10 parts per 100 parts of the solid content of the polyurethane resin. It is preferably used in an amount of 5 parts or less.

Examples of the chain extender which can be used in the present invention include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine,
2-methylpiperazine, 2,5-dimethylpiperazine,
Isophoronediamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, aminoethylethanolamine, aminopropylethanol Amine,
Diamines such as aminohexylethanolamine, aminoethylpropanolamine, aminopropylpropanolamine and aminohexylpropanolamine; polyamines such as diethylenetriamine, dipropylenetriamine and triethylenetetramine; hydrazines; acid hydrazides, and these alone Alternatively, they are used in combination. The amount of the chain extender used is not particularly limited, but in an equivalent ratio, amino group / isocyanate group in prepolymer = 0/1 to 1/1, preferably 0.6 / 1 to
It needs to be 0.98 / 1.

The polyurethane resin aqueous dispersion thus obtained is further concentrated by distilling off the organic solvent and / or water. Various types of distillation apparatuses can be used for distilling and removing the organic solvent and / or water, 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.

A particularly preferable continuous type thin film evaporation apparatus used in the present invention is, for example, “Chemical Equipment Handbook, No. 4”.
04-407 (1989) ”, such as a stir-film evaporator of the type described in Hitachi, Ltd., for example, Cebucon evaporator, horizontal controller or vertical controller, WFE thin film manufactured by Shinko Faudler Co., Ltd. Examples of the apparatus include a distillation apparatus. Among them, a vertical apparatus having a rotating shaft installed in a vertical direction may have no liquid pool.

Distillation is generally carried out at a jacket temperature of the apparatus of about 20 to 100 ° C., preferably 30 to 90 ° C., and a reduced pressure of about 5 to 300 mmHg, preferably 10 to 200 mmH.
performed under the conditions of g.

In the production method of the present invention, if necessary, in addition to water, other aqueous dispersions such as vinyl acetate type, ethylene vinyl acetate type, acrylic type, acrylic styrene type emulsion; styrene-butadiene Polymers, acrylonitrile-butadiene-based, acrylic-butadiene-based latexes; polyethylene-based, polyolefin-based ionomers; various emulsions such as polyurethane, polyester, polyamide, and epoxy resins, and aqueous dispersions may be used in combination.

Thus, the method of the present invention provides a solids content of about 4%.
A polyurethane resin aqueous dispersion having a high solid content of 0 to 65% is obtained. The polyurethane resin aqueous dispersion obtained by the method of the present invention includes other aqueous dispersions such as vinyl acetate-based, ethylene vinyl acetate-based, acrylic-based, acrylic styrene-based emulsions; styrene-butadiene-based, acrylonitrile-based emulsions.
It can be used by blending with a latex of butadiene type, acrylic-butadiene type, etc .; an ionomer type aqueous dispersion of polyethylene type, polyolefin type, etc .; an aqueous dispersion of polyurethane, polyester, polyamide, epoxy type in an arbitrary ratio. Further, fillers such as carbon black, clay, talc and aluminum hydroxide; additives such as silica sol, alumina sol, plasticizer and pigments; film forming aids such as alkylene glycol derivatives; epoxy resins, melamine resins, isocyanate compounds, aziridine. Compound,
A cross-linking agent such as a polycarbodiimide compound; a leveling agent, etc. may be blended and used.

The polyurethane resin aqueous dispersion obtained by the method of the present invention is various plastics such as vinyl chloride, nylon, polyester, polyurethane, etc., textile products, synthetic leather products, or metals such as aluminum, copper and iron, paper, wood. , Excellent adhesion to glass, etc., for example, impregnating agents or coating agents for fibers and synthetic products, adhesives for various substrates, coating agents, water-based paints, water-based inks or base resins for sizing agents for organic and inorganic fibers Can be widely used as.

[0039]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples without departing from the technical idea of the present invention. However, all parts and% in the examples are by weight. Example 1 First, polycaprolactone diol (OH value 56) was placed in a 4-necked flask equipped with a thermometer, a stirrer, and a reflux condenser.
1800 parts were added, dehydration was carried out under reduced pressure at 120-130 ° C., then cooling to 50 ° C., 104 parts 1,6-hexanediol, 96 parts dimethylolpropionic acid and 11 parts.
After adding 55 parts of toluene and thoroughly stirring and mixing, 696 parts of Coronate T-80 (2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate = 8/2 mixture manufactured by Nippon Polyurethane Industry Co., Ltd.) were added, 70 ° C
The mixture was warmed to room temperature and reacted at this temperature for 6 hours to obtain a prepolymer solution having a terminal isocyanate group. Then, 1959 parts of an aqueous solution in which 72 parts of triethylamine was dissolved was added to this prepolymer, and it was subjected to mechanical shearing force (10 kw / m) by using Supraton (mixer) manufactured by Tsukishima Kikai Co., Ltd.
^The mixture was thoroughly mixed under high-speed stirring under ³ · hr ⁻¹ ) to prepare an aqueous dispersion of the prepolymer, and 453 parts of an aqueous solution containing 122 parts of anhydrous piperazine was added dropwise over about 1 minute. The milky white aqueous dispersion thus obtained is distilled under reduced pressure at 60 ° C. to obtain a solid content of 60% and a viscosity of 880.
An aqueous dispersion of polyurethane in cps was obtained. The particle size of the polyurethane resin particles in the dispersion was 0.8 μm.

When this aqueous dispersion was used as an adhesive between a polyvinyl chloride film and a cloth, the drying time was short,
The initial adhesion was also good. Comparative Example 1 A polyurethane aqueous dispersion was prepared in the same manner as in Example 1 except that a propeller stirrer that did not generate mechanical shearing force was used in place of the homogenizer. However, the emulsification was insufficient and anhydrous piperazine was added at the same time. No viscous and stable aqueous dispersion was obtained. Comparative Example 2 Example 1 except that acetone was used instead of toluene.
A polyurethane aqueous dispersion was prepared in the same manner as
The solid content was 50% and the viscosity was 1600 cps.

When this aqueous dispersion was used as an adhesive between a polyvinyl chloride film and a cloth, the drying time was longer than in Example 1 and the initial adhesion was poor. Example 2 In the same manner as in Example 1, 1259 parts of ethylene glycol / neopentyl glycol / adipic acid polyester (OH value 112), 88 parts of neopentyl glycol, 53 parts of dimethylolpropionic acid, 833 An isocyanate terminated prepolymer was obtained from 1 part isophorone diisocyanate, 0.2 parts stannous octylate and 1202 parts toluene. Then 4 in this prepolymer
1490 parts of an aqueous solution in which 0 part of triethylamine was dissolved was added, and this was added to Supraton (mixer) manufactured by Tsukishima Kikai Co., Ltd.
To mix with high speed stirring under mechanical shearing force (10 kw / m ³ · hr ⁻¹ ) to prepare an aqueous dispersion of prepolymer, and further 270 parts of an aqueous solution containing 105 parts of anhydrous piperazine dissolved therein for about 1 minute. Was added dropwise. The milky white aqueous dispersion thus obtained was distilled under reduced pressure at 60 ° C. to obtain a polyurethane aqueous dispersion having a solid content of 60% and a viscosity of 460 cps.

The particle size of the polyurethane resin particles in the dispersion was 1.1 μm. When this aqueous dispersion was used as an adhesive between a polyvinyl chloride film and a cloth, the drying time was short and the initial adhesiveness was good. Comparative Example 3 A polyurethane aqueous dispersion was prepared in the same manner as in Example 2 except that a propeller stirrer that did not generate mechanical shearing force was used in place of the homogenizer. However, the emulsification was insufficient and anhydrous piperazine was added at the same time. No viscous and stable aqueous dispersion was obtained. Comparative Example 4 Example 2 except that acetone was used instead of toluene.
A polyurethane aqueous dispersion was prepared in the same manner as
The solid content was 50% and the viscosity was 1000 cps.

When this aqueous dispersion was used as an adhesive between a polyvinyl chloride film and a cloth, the drying time was longer and the initial adhesion was poorer than in Example 2. Example 3 In the same manner as in Example 1, 1931 parts of 1,6-hexanediol / neopentyl glycol / adipic acid polyester (OH value 56), 74.5 parts of 1,4-butanediol, 94 0.7 parts of dimethylolpropionic acid, 108
An isocyanate terminated prepolymer was obtained from 1 part 4,4'-dicyclohexylmethane diisocyanate, 0.3 parts stannous octylate and 795 parts toluene. Then, 2139 parts of an aqueous solution in which 71 parts of triethylamine and 159 parts of Latemur PS [anionic emulsifier manufactured by Kao Soap; solid content 40%] were dissolved in this prepolymer were added to the supraton manufactured by Tsukishima Kikai Co., Ltd. Mixing under mechanical shearing force (10 kw / m ³ · hr ⁻¹ ) with high speed stirring to prepare an aqueous dispersion of the prepolymer, and further about 648 parts of an aqueous solution containing 137 parts of anhydrous piperazine dissolved therein. It dripped over 1 minute. The milky white aqueous dispersion thus obtained was distilled under reduced pressure at 60 ° C. to obtain a polyurethane aqueous dispersion having a solid content of 60% and a viscosity of 260 cps. The particle size of the polyurethane resin particles in the dispersion was 1.0 μm.

When this aqueous dispersion was used as an adhesive between a polyvinyl chloride film and a cloth, the drying time was short,
The initial adhesion was also good. Comparative Example 5 A polyurethane aqueous dispersion was prepared in the same manner as in Example 3 except that a propeller stirrer that did not generate mechanical shearing force was used in place of the homogenizer. However, the emulsification was insufficient and anhydrous piperazine was added at the same time. No viscous and stable aqueous dispersion was obtained. Comparative Example 6 Example 3 except that acetone was used instead of toluene.
A polyurethane aqueous dispersion was prepared in the same manner as
The solid content was 50% and the viscosity was 1800 cps.

When this aqueous dispersion was used as an adhesive between a polyvinyl chloride film and a cloth, the drying time was longer than in Example 3 and the initial adhesion was poor.

[0046]

EFFECTS OF THE INVENTION According to the production method of the present invention, while maintaining the stability of the aqueous dispersion over time, which is difficult with the conventional method for producing an aqueous dispersion of a polyurethane resin using a hydrophilic organic solvent, The particle size of the liquid can be made uniform and large, which makes it possible to easily produce a high solid content polyurethane resin aqueous dispersion having excellent long-term stability or mechanical stability.

Since the aqueous dispersion of polyurethane resin obtained by the present invention has a high solid content as compared with the conventional aqueous dispersion of polyurethane resin, it requires less drying energy,
The low-temperature drying property and the drying time can be shortened, and when it is used as an adhesive, the initial adhesive property is remarkably improved, and the workability in various bonding processes is expected to be improved.

Further, the polyurethane resin aqueous dispersion obtained in the present invention has a uniform particle size containing no coarse particles.
Even when it is used as a coating agent, the dried film is excellent in transparency, smoothness, gloss, water resistance and mechanical strength, and at the same time, it is excellent in adhesion to various substrates.

Claims (3)

[Claims] (1) A solution of a hydrophilic group-containing isocyanate-terminated prepolymer in a hydrophobic organic solvent is mixed with water optionally containing a neutralizing agent under mechanical shearing force and dispersed in an aqueous medium. Then, it is reacted with a chain extender or a solution of a hydrophilic group-containing isocyanate-terminated prepolymer in a hydrophobic organic solvent is added with water containing a chain extender and optionally a neutralizing agent under mechanical shearing force. A method for producing an aqueous dispersion of a high-solid content polyurethane resin, which comprises mixing and carrying out a chain extension reaction and dispersion in an aqueous medium at the same time, followed by (2) solvent removal under reduced pressure. 2. The method for producing an aqueous dispersion of a high-solid content polyurethane resin according to claim 1, wherein the water mixed under mechanical shearing force contains an emulsifier. 3. The method for producing an aqueous dispersion of a high-solid content polyurethane resin according to claim 2, wherein the emulsifier is an anionic or nonionic anionic emulsifier.