JP2000178335A - Polyisocyanate composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyisocyanate compsn. having a low viscosity and excellent workability, capable of being easily stirred when preparing an aq. coating compsn., and attaining a long pot life, and effective as a coating substituting for a solvent type polyurethane coating, especially such as a coating for repainting exterior of buildings, a coating for repair of automobiles, and a coating for plastics. SOLUTION: This highly emulsifying polyisocyanate compsn. comprises 50-95 wt.% isocyanate prepolymer obtainable from an aliphatic or alicyclic diisocyanate and 1-50C monoalcohol (a), 5-50 wt.% nonionic hydrophilic component having at least a hydroxy group and comprising repeated units of 3-50 ethylene oxides, (b) and, if desired, 0.5-20 wt.% ionic surfactant contg. essentially no water. This aq. coating compsn. is prepared by blending the isocyanate compsn. (A) and an aq. emulsion (B) at an equivalent ratio of isocyanate/ hydroxy group = 0.5-5.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyisocyanate composition having a high emulsifying property, and a coating composition of a two-component aqueous crosslinking urethane comprising an aqueous emulsion and a polyisocyanate composition. For details,
The water-based coating composition of the present invention is excellent in pot life, water resistance, water dispersibility, mainly water-based paint for construction, water-based paint for automobiles, adhesives, building materials, water-based paint for home use, other coating agents, sealing agents, It can be effectively used for inks, casting materials, elastomers, foams, plastic raw materials, and fiber treatment agents.

[0002]

2. Description of the Related Art In recent years, guidelines on volatile organic compounds have become strict, and regulations have already been implemented in the United States and Germany, and it is expected that regulations will be implemented in Japan in the near future. Therefore, it has been desired that the cold-crosslinkable two-pack urethane coating composition conventionally used as a solvent-based coating composition be converted to an aqueous system. However, the polyisocyanate used as a curing agent in the two-part urethane coating composition is difficult to disperse in water, easily reacts with water, and has a problem of generating carbon dioxide. Development of a polyisocyanate capable of suppressing a reaction between an isocyanate group and water in a water-dispersed state has been promoted.

[0003] Japanese Patent Publication No. 55-7472, Japanese Unexamined Patent Publication No.
No. 222150 discloses a water-dispersible polyisocyanate in which a nonionic hydrophilic group is introduced into a polyisocyanate as a method for obtaining a polyisocyanate having a high emulsifying property, but the pot life when emulsified is reduced. There was the disadvantage of being short. Japanese Patent Application Laid-Open No. Hei 9-71720 proposes a water-dispersed polyisocyanate composition comprising a nonionic hydrophilic group-introduced polyisocyanate and an ionic surfactant, and the pot life of a coating composition combined with an aqueous polyol is dramatically increased. Although a coating film which is extended in length and has excellent water resistance was achieved, the viscosity sometimes increased, and in some cases, the viscosity was reduced by adding an organic solvent.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-viscosity polyisocyanate composition having high emulsifying properties and an aqueous coating composition using the same.

[0005]

As a result of various studies on the above problems, the present inventors have found that the above problems can be solved by incorporating a monoalcohol into a polyisocyanate composition having a high emulsifying property. Was completed. That is, the present invention provides: (a) 50 to 95% by weight of an isocyanate prepolymer obtained from an aliphatic and / or alicyclic diisocyanate and a monoalcohol having 1 to 50 carbon atoms;
Nonionic hydrophilic component having at least one hydroxyl group and comprising 3 to 50 ethylene oxide repeating units.
A polyisocyanate composition having high emulsifiability by reacting with 0% by weight. Further, there is provided a polyisocyanate composition having high emulsifiability comprising the polyisocyanate composition described above and (c) 0.5 to 20% by weight of an ionic surfactant containing substantially no water. Further, (A) an aqueous emulsion having a hydroxyl value of 1 to 300 mgKOH / g and (B) the polyisocyanate composition described in 1 or 2 above, in an isocyanate group / hydroxyl group equivalent ratio of 0.5 to 5.0. An aqueous coating composition is provided.

Hereinafter, the present invention will be described in detail. (1) Polyisocyanate composition The polyisocyanate composition of the present invention comprises: (a) an aliphatic and / or alicyclic diisocyanate;
0 to 50% by weight of an isocyanate prepolymer obtained from a monoalcohol, and (b) 5 to 50% by weight of a nonionic hydrophilic component having at least one hydroxyl group and comprising 3 to 50 ethylene oxide repeating units. It is obtained by reacting. Furthermore, (c) 0.5 to 20% by weight of an ionic surfactant containing substantially no water can be contained. That is, (a) isocyanate prepolymer (i) diisocyanate component As the aliphatic and / or alicyclic diisocyanate used in the present invention, for example, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (hereinafter, HDI), Trimethylhexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate (hereinafter, IPDI),
Examples include hydrogenated xylene diisocyanate, 1,4-diisocyanate cyclohexane, and the like. HDI and I
PDI and hydrogenated xylene diisocyanate are easily available industrially and are good.

(Ii) Monoalcohol component The monoalcohol having 1 to 50 carbon atoms used in the present invention is:
It is a linear or side chain aliphatic monoalcohol or alicyclic alcohol, or a monoalcohol having an ether group or an ester group in the molecule. The carbon number of monoalcohol is
1 to 50, preferably 3 to 20, more preferably 6 to 9
It is. If the number of carbon atoms exceeds 50, the effect of lowering the viscosity of the polyisocyanate composition may not be obtained, which is not preferable. Examples of the monoalcohol component include n-propanol, i-propanol, n-butanol and i-propanol.
Butanol, n-pentanol, n-hexanol, n
Aliphatic alcohols such as octanol, 2-octanol, 2-ethylhexanol, nonanol, decanol and tridecanol; alicyclic alcohols such as cyclohexanol and 4-methylcyclohexanol: alcohols having an ester group such as cellosolve acetate and cellosolve butyrate. And the like, with n-hexanol, 2-octanol and 2-ethylhexanol being particularly preferred.

The amount of the monoalcohol used is 1 to 50% by weight, preferably 3 to 40% by weight, more preferably 5 to 30% by weight, based on the isocyanate prepolymer. If it is less than 1% by weight, the effect of lowering the viscosity may be small, which is not preferable. If it exceeds 50% by weight, the crosslink density of the coating film is lowered, and the coating film may be weakened, which is not preferable.

(Iii) Characteristics of isocyanate prepolymer The above-mentioned aliphatic and / or alicyclic diisocyanate and the isocyanate prepolymer obtained from a monoalcohol having 1 to 50 carbon atoms include buret, isocyanurate and urethane in the molecule. , Uretdione, allophanate and the like. Among the isocyanate prepolymers, those having a burette structure have excellent adhesiveness, those having an isocyanurate structure have excellent weather resistance, those having a urethane structure using an alcohol compound having a long side chain have elasticity and Those having excellent extensibility and having a uretdione structure or an allophanate structure are characterized by low viscosity.

In the present invention, the viscosity of the isocyanate prepolymer can be reduced by incorporating the monoalcohol into the structure of the isocyanate prepolymer. As a method of incorporating into the isocyanate prepolymer structure, for example, biuretization of diisocyanate,
Performing isocyanuration, urethanization, uretdionation, or reacting with a monoalcohol before or simultaneously. A polyisocyanate composition obtained by subjecting a diisocyanate and a monoalcohol to urethanization and then isocyanuration is particularly preferred because of its low viscosity.

In the present invention, the isocyanate prepolymer is used in an amount of 50 to 95% by weight, preferably 60 to 90% by weight, more preferably 70 to 85% by weight based on the polyisocyanate composition having a solid content of substantially 100%. % By weight. If the amount is less than 50% by weight, the components involved in crosslinking are reduced, and the coating film may become brittle when formed. 95
If the amount is more than 10% by weight, the emulsifying ability may decrease because the number of hydrophilic groups decreases. The “substantially 100% solids state” in the present invention refers to a state in which a volatile component such as a diisocyanate or a solvent is not substantially contained in a polyisocyanate composition. A state in which a volatile component is 1% or less in the substance. In addition,
As will be described later, the polyisocyanate composition of the present invention may be used by mixing an organic solvent or the like when actually used.

(B) Nonionic hydrophilic component The nonionic hydrophilic component comprising an ethylene oxide repeating unit used in the present invention is a polyalkylene oxide ether alcohol containing an ethylene oxide repeating unit. In this case, the number of hydroxyl groups in the hydrophilic component is
At least one, but preferably one. Such compounds include polyethylene glycol, pluronic type polyalkylene glycol, etc., and particularly preferred is polyethylene glycol monomethyl ether. The number of ethylene oxide repeating units is 3 to 50, preferably 3 to 30, more preferably 4 to 1.
0. If the number of ethylene oxide repeating units is less than 3, the emulsifying ability may decrease, which is not preferable. 50
If it exceeds, the crystallinity of the polyisocyanate composition may be high, and the composition may be easily solid.

The nonionic hydrophilic component can be incorporated into the structure of the polyisocyanate composition by reacting its hydroxyl group with the terminal isocyanate group of the isocyanate prepolymer to have a function as a surfactant. The emulsifying ability of the polyisocyanate composition can be improved. The amount of the nonionic hydrophilic component used in the present invention is 5 to 50% by weight, preferably 10 to 40% by weight.
%, More preferably 15 to 30% by weight. If it is less than 5% by weight, sufficient emulsifying ability may not be exhibited. If the content exceeds 50% by weight, the hydrophilicity of the polyisocyanate composition becomes too high, so that the reaction between the isocyanate group and water when emulsified may not be suppressed in some cases.

(C) Ionic surfactant The polyisocyanate composition of the present invention further contains 0.5 to 20% by weight, preferably 0.7 to 12% by weight of an ionic surfactant substantially containing no water. %, More preferably 1.0 to 8% by weight. The term "substantially free of water" as used in the present invention means that water and isocyanate groups contained in the ionic surfactant react with each other to prevent foaming, clouding and increase in viscosity. 1% by weight or less based on the weight of the surfactant. The ionic surfactant is determined to be anionic or cationic depending on the method of neutralizing the aqueous emulsion. That is,
It is preferable to use an anionic surfactant when the aqueous emulsion is neutralized with a base, and to use a cationic surfactant when neutralized with an acid. If the aqueous emulsion is not neutralized, either may be used.

(I) Anionic surfactant As the anionic surfactant, carboxylate type,
Sulfate, sulfonate and phosphate types are suitable. For example, ammonium alkyl benzene sulfonate, sodium alkyl disulfate, sodium alkyl diphenyl ether disulfonate, sodium dialkyl sulfosuccinate and the like can be mentioned. (ii) Cationic surfactant As the cationic surfactant, quaternary ammonium salts, pyridinium salts, and imidazolinium salts are suitable. For example, alkyltrimethylammonium bromide, alkylpyridinium bromide and imidazolinium laurate can be mentioned. (iii) Critical significance of added amount of ionic surfactant If the added amount is less than 0.5% by weight, the effect of water dispersion stability by mixing the ionic surfactant is not exhibited, so that it is not suitable. . If it exceeds 20% by weight, components that do not participate in crosslinking may increase too much, which may cause the coating such as a coating film to become brittle.

(D) Characteristics of Polyisocyanate Composition (i) Combination of Nonionic Hydrophilic Component and Ionic Surfactant By using a nonionic hydrophilic component and an ionic surfactant together, polyisocyanate oil droplets By forming a protective film of a nonionic hydrophilic group and an ionic surfactant on the surface, the aqueous dispersion stability and long pot life of the polyisocyanate composition can be achieved. (ii) Isocyanate group content The isocyanate group content in the polyisocyanate composition having high emulsifiability of the present invention is substantially 100% solids.
%, 3 to 24% by weight, preferably 6 to 20% by weight, more preferably 8 to 18% by weight. If it is less than 3% by weight, the number of cross-linking points in the coating composition decreases,
It has the disadvantage of causing a decrease in the curing speed or weakening of a coating such as a coating film. Further, since the isocyanate group content is uniquely determined from the amount of introduction of the hydrophilic group and the molecular weight, when a hydrophilic group necessary for having a high emulsifying ability is introduced, the upper limit is necessarily 24% by weight or less. .

(Iii) Viscosity The polyisocyanate composition of the present invention has a viscosity of 50 to 3000 mP at 25.degree.
a. s, preferably 200 to 2000 mPa.s. s, more preferably 500 to 1500 mPs. s. 300
If it exceeds 0 mPa · s, the workability, especially at low temperatures, may decrease. Considering the dispersion in water, the lower the viscosity is, the more desirable it is. If it is less than s, the average number of functional groups may decrease, and the crosslinking ability may decrease.

(Iv) State of Polyisocyanate Composition The polyisocyanate composition used in the present invention is desirably "emulsified" and used in the form of an aqueous dispersion.
The emulsification referred to in the present invention means that the polyisocyanate composition is
/ W type is a state in which the polyisocyanate composition is added to water and mechanically stirred using a stick, a hand mixer or the like.

The polyisocyanate composition of the present invention comprises:
An organic solvent may be added. Since the polyisocyanate composition mixed with an organic solvent has a low viscosity, it has an effect of improving water dispersibility, further increasing the residual ratio of isocyanate groups during water dispersion, and prolonging the pot life. In this case, it is necessary that the organic solvent does not have a functional group that reacts with the isocyanate group. The organic solvent must be compatible with the polyisocyanate composition of the present invention. Such organic solvents include, for example, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, methoxypropyl acetate, 3-methoxybutyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate,
Ester compounds such as cyclohexyl acetate, methyl propionate, butyl propionate, butyl butyrate, dioctyl adipate, diisopropyl glutarate: ether compounds such as diisopropyl ether, dibutyl ether, dioxane, and diethoxyethane:

2-pentanone, 3-pentanone, 2-
Hexanone, methyl isobutyl ketone 2-heptanone,
Ketone compounds such as 4-heptanone, diisobutyl ketone, isophorone, cyclohexanone, and methylcyclohexanone: aromatic compounds such as benzene, toluene, xylene, ethylbenzene, butylbenzene, and p-cymene: diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, and the like Polyethylene glycol dialkyl ether-based compounds: polyethylene glycol dicarboxylate-based compounds such as diethylene glycol diacetate.

The amount of the organic solvent added to the highly emulsifiable polyisocyanate composition of the present invention is preferably 1 to 50% by weight. If it is less than 1% by weight, there is no merit of mixing an organic solvent, that is, no improvement in water dispersibility or an effect of extending the pot life is obtained. If it exceeds 50% by weight, the amount of the volatile organic compound in the water-based coating composition of the present invention is undesirably increased.

(2) Aqueous coating composition The present invention further comprises a component (A) having a hydroxyl value of 1 to 300 mg.
An aqueous emulsion of KOH / g and a polyisocyanate composition having a high emulsifiability of the component (1) as the component (B) are mixed with an isocyanate group / hydroxyl group equivalent ratio of 0.5 to 0.5.
The present invention provides a water-based coating composition formulated in a range of 5.0.

(A) Aqueous emulsion The aqueous emulsion used in the present invention includes all of latex and emulsion. For example, polyvinylidene chloride copolymer, polyvinyl chloride copolymer,
Examples include vinyl acetate copolymer, urethane emulsion, acrylic emulsion, fluorine copolymer emulsion, styrene butadiene copolymer latex, acrylonitrile butadiene copolymer, rubber latex, polybutadiene copolymer, urethane acrylic emulsion and the like. Urethane emulsions, acrylic emulsions, and fluoropolymer emulsions are particularly preferred.

(I) Hydroxyl value The hydroxyl value of the aqueous emulsion used in the present invention is from 1 to
300 mg KOH / g, preferably 5-150 mg KO
H / g, more preferably 10 to 100 mgKOH / g. If the amount is less than 1 mgKOH / g, the number of crosslinking points in the coating composition decreases, which may cause a decrease in the curing speed or weakening of a coating such as a coating film, which is not preferable. If it exceeds 300 mgKOH / g, on the contrary, since the number of crosslinking points is too large, the coating may be hard and brittle.
Incidentally, the hydroxyl value in the present invention is a value with respect to the non-volatile component of the aqueous emulsion.

(Ii) Particle size The particle size of the aqueous emulsion used in the present invention is 0.0
It is 1 to 1.0 μm, preferably 0.02 to 0.5 μm, more preferably 0.05 to 0.2 μm. 0.01μ
If it is less than m, the viscosity of the aqueous emulsion may increase, which is not preferable. If it exceeds 1.0 μm, the stability of the aqueous dispersion of the aqueous emulsion may deteriorate, which is not preferable.

(Iii) Isocyanate group of component (A) / (B)
In the present invention, the equivalent ratio of isocyanate group / hydroxyl group in the aqueous emulsion (A) and the high emulsifiable polyisocyanate composition (B) is 0.5 to 5.0, preferably 0.8 to 0.8. ~ 3.
0, more preferably 1.0 to 2.0. If it is less than 0.5, the number of cross-linking points in the coating composition decreases, which may cause a decrease in the curing rate or weakening of a coating such as a coating film, which is not preferable. If it exceeds 5.0, the coating may be hard and brittle, which is not preferable.

(4) Characteristics of the polyisocyanate composition and the water-based coating composition containing the same: The polyisocyanate composition having high emulsifiability and the water-based coating composition of the present invention may contain, if necessary, Stabilizers, viscosity modifiers, leveling agents, light stabilizers, antioxidants, ultraviolet absorbers, fillers, plasticizers,
A lubricant, a curing acceleration catalyst, and the like can be added. The polyisocyanate composition having high emulsifiability of the present invention is excellent in workability because the viscosity can be reduced, and can be easily stirred when mixed with an aqueous emulsion to prepare a water-based coating composition. . Further, the polyisocyanate composition using the ionic activator suppresses the reaction between the isocyanate group and water in a water-dispersed state, so that a long pot life can be achieved when used in an aqueous coating composition. Accordingly, it can be used as a coating material in which a solvent-based polyurethane coating material has been used conventionally, particularly as a coating material for repainting an architectural exterior, a coating material for automobile repair, or a plastic coating material. Furthermore, it can be applied to a wide range of fields such as sealing agents, adhesives, inks, coating materials, casting materials, elastomers, foam and plastic raw materials, and fiber treatment agents.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The measuring method and the adjusting method used in the present invention are described below. <Measurement Method> Isocyanate Group Content The isocyanate group content was determined by adding 10 ml of toluene to about 2 g of the sample, neutralizing the isocyanate group with an excess of 2N amine (toluene solution), and performing back titration with 1N hydrochloric acid. Viscosity The viscosity was measured at 25 ° C. using an E-type viscometer (manufactured by Tokimec Co., Ltd.). Weight average molecular weight The weight average molecular weight was determined by using gel permeation chromatography (GPC). In addition, GPC (column: TSKgelSuper100 manufactured by Tosoh Corporation)
0, TSKgelSuper2000, TSKgelS
upper 3000, carrier: THF, detection method: parallax refractometer). Particle size The particle size is measured using a Microtrac UPA particle size distribution analyzer (Lee
ds + Northrup).

<Preparation Method> Aqueous Dispersion The aqueous dispersion was prepared by mixing the polyisocyanate composition: water in a ratio of 40: 6.
The mixture was prepared by mixing at a weight ratio of 0 and stirring at 600 rpm for 10 minutes. Water-based coating composition The water-based coating composition is prepared by adding a predetermined amount of a polyisocyanate composition to an aqueous emulsion, and adding 1 at 600 rpm.
It was made by stirring for 0 minutes.

[0030]

[Synthesis Example 1 of Isocyanate Prepolymer] 500 g of HDI and 15 g of 2-ethyl-1-hexanol were charged into a four-necked flask equipped with a stirrer, a thermometer and a condenser, and urethanized at 80 ° C. for 2 hours with stirring. The reaction was performed to complete the urethanization. Then, at 80 ° C., 0.015 g of tetramethylammonium capryate was added as an isocyanuration catalyst. After 4 hours, when the conversion to polyisocyanate becomes 28% by measurement of the isocyanate group content and the refractive index of the reaction solution, phosphoric acid 0.0
The reaction was stopped by adding 6 g. The increase in the refractive index immediately after the addition of the catalyst poison was 0.011.

After the precipitates were removed by filtration, the first 0.3 torr. (155
° C), 0.2 Tor. Unreacted H at (145 ° C)
DI was removed. The resulting polyisocyanate composition was a pale yellow, transparent liquid, with a yield of 144 g and a viscosity of 5
50 mPa · s, the isocyanate group content was 20.8% by weight. The amount of the component derived from 2-ethyl-1-hexanol contained therein was 10%.

[0032]

[Synthesis example 2 of isocyanate prepolymer] HDI was added to the same apparatus as in synthesis example 1 of isocyanate prepolymer.
Then, 00 g and 50 g of 2-ethyl-1-hexanol were charged, and a urethanization reaction was performed at 90 ° C. for 2 hours with stirring to complete the urethanization. Then, at 90 ° C., 0.03 g of tetramethylammonium capryate as an isocyanuration catalyst was added. Four hours later, when the conversion of polyisocyanate to 47% was measured by measuring the isocyanate group content and the refractive index of the reaction solution, phosphoric acid 0.07% was added.
g was added to stop the reaction. The increase in the refractive index immediately after the addition of the catalyst poison was 0.015. Then, purification was performed in the same manner as in Example 1. The obtained polyisocyanate composition,
Light yellow, clear liquid, yield 258g, viscosity 410
mPa · s, isocyanate group content is 17.6% by weight
Met. The content of the component derived from 2-ethyl-1-hexanol contained therein was 19%.

[0033]

[Synthesis Example 1 of Aqueous Emulsion] In a 2 liter four-necked flask equipped with a dropping funnel and a mechanical stirrer, 675 g of water and emanol NC (anionic surfactant, 3
5% aqueous solution, manufactured by Kao Corporation) at 80 ° C
And 8 g of ammonium persulfate (2% aqueous solution) was added as an initiator. Next, the following mixture was dropped into the flask over 4 hours, and the temperature was kept at 80 ° C. for 1 hour after completion of the dropping. 25 g of 2-hydroxymethyl methacrylate (3.5% by weight) 10 g of acrylic acid (1.4% by weight) 2 g of acrylamide (0.3% by weight) 27 g of glycidyl methacrylate (3.8% by weight) 353 g of methyl methacrylate (49.%) 0 wt%) Butyl acrylate 293 g (40.7 wt%) Styrene 9 g (1.3 wt%) Water 400 g Ammonium persulfate (2% aqueous solution) 31 g Eleminor JS-2 (Note 1) 38 g Emulgen 920 (Note 2) 9 g

(Note 1) Reactive emulsifier, 39% aqueous solution, manufactured by Sanyo Kasei Co., Ltd. (Note 2) Nonionic surfactant, 25% aqueous solution, Kao Corporation The obtained aqueous emulsion is milky white, solid content of 38%, stable And the particle size was 0.1 μm. Hydroxyl value 15.0 mgKOH / g, acid value 1
0.8 mgKOH / g, glass transition point temperature was 15.7 ° C.

[0035]

Example 1 Methoxy polyethylene glycol (MPG
-130, ethylene oxide repeating unit = 9.4
Pieces, manufactured by Nippon Emulsifier Co., Ltd.) and sodium dioctyl sulfosuccinate (Newcol 291M, solid content 70%,
(Nippon Emulsifier Co., Ltd.) was mixed at a solid content weight ratio of 3: 1, and water and the solvent were removed by distillation under reduced pressure.
100 g of the isocyanate prepolymer obtained in Synthesis Example 1 of the isocyanate prepolymer and 25 g of a mixture of methoxypolyethylene glycol and sodium dioctylsulfosuccinate obtained above were mixed, and a urethanization reaction was performed at 90 ° C. for 8 hours.

The obtained polyisocyanate composition is a pale yellow liquid having an isocyanate group content of 15.5.
%, Weight average molecular weight is 1000, viscosity is 1040 mPa
-It was s. When the polyisocyanate composition is dispersed in water, the dispersibility is good. When the aqueous dispersion is left at 20 ° C. for 6 hours, the residual ratio of the isocyanate group content is 90%.
%Met.

[0037]

Example 2 Methoxy polyethylene glycol (MPG
-130, ethylene oxide repeating unit = 9.4
Pieces, manufactured by Nippon Emulsifier Co., Ltd.) and sodium dialkyl sulfosuccinate (Newcol 291M, solid content 70%,
(Manufactured by Nippon Emulsifier Co., Ltd.) at a solid content weight ratio of 4: 1, and water and solvent were removed by distillation under reduced pressure.
100 g of the isocyanate prepolymer obtained in Synthesis Example 2 of the isocyanate prepolymer and 20 g of the mixture of methoxypolyethylene glycol and sodium dialkylsulfosuccinate obtained above were mixed, and a urethanization reaction was performed at 90 ° C. for 8 hours. The obtained polyisocyanate composition is a pale yellow liquid, has an isocyanate group content of 12.5%, a weight average molecular weight of 900 and a viscosity of 720.
mPa · s. When this polyisocyanate is dispersed in water, the dispersibility is good. When the aqueous dispersion is left at 20 ° C. for 6 hours, the residual ratio of the isocyanate group content is 85%.
%Met.

[0038]

Example 3 Methoxy polyethylene glycol (MP
G, 4.2 units of ethylene oxide repeating units (manufactured by Nippon Emulsifier Co., Ltd.) and sodium dialkyl sulfosuccinate (Newcol 291M, solid content 70%, manufactured by Nippon Emulsifier Co., Ltd.) in a weight ratio of solid content of 9: 1. And water and solvent were removed by vacuum distillation. 100 g of the isocyanate prepolymer obtained in Synthesis Example 1 of the isocyanate prepolymer and 25 g of a mixture of methoxypolyethylene glycol and sodium dioctylsulfosuccinate obtained above were mixed, and a urethanization reaction was performed at 90 ° C. for 8 hours. The obtained polyisocyanate composition is a pale yellow liquid and has an isocyanate group content of 1
2.6%, weight average molecular weight 800, viscosity 1300m
Pa · s. When this polyisocyanate is dispersed in water, the dispersibility is good. When the aqueous dispersion is left at 20 ° C. for 6 hours, the residual ratio of the isocyanate group content is 70%.
Met.

[0039]

Example 4 100 g of the isocyanate prepolymer obtained in Synthesis Example 1 and methoxypolyethylene glycol (M
PG-130, ethylene oxide repeating unit = 9.
20 g of the mixture (4 pieces, manufactured by Nippon Emulsifier Co., Ltd.) were mixed, and a urethanization reaction was performed at 90 ° C. for 8 hours. The obtained polyisocyanate composition was a pale yellow liquid, the isocyanate group content was 15.5%, the weight average molecular weight was 800, and the viscosity was 710 mPa · s. When this polyisocyanate composition is dispersed in water, the dispersibility is good.
The residual ratio of the isocyanate group content when left at 0 ° C. for 3 hours was 80%, and the residual ratio of the isocyanate group content when left at 20 ° C. for 6 hours was 0%.

[0040]

Example 5 Synthesis of Aqueous Emulsion The aqueous emulsion obtained in Synthesis Example 1 and the polyisocyanate composition obtained in Example 1 were mixed at an equivalent ratio of isocyanate groups to hydroxyl groups = 1.5 to obtain an aqueous coating composition. . This aqueous coating composition did not show an increase in viscosity or foaming even after being left at 20 ° C. for 8 hours. Using this coating composition, a coating film having a thickness of 40 μm was prepared, and was coated at 20 ° C. and 65% RH for 24 hours.
After curing for a time, a transparent coating film was obtained. The gel fraction was measured to be 79%. No whitening of the coating film was observed even after immersion in water at 20 ° C. for 4 hours.

[0041]

Comparative Example 1 Methoxy polyethylene glycol (MPG
-130, ethylene oxide repeating unit = 9.4
Pieces, manufactured by Nippon Emulsifier Co., Ltd.) and sodium dioctyl sulfosuccinate (Newcol 291M, solid content 70%,
(Nippon Emulsifier Co., Ltd.) was mixed at a solid content weight ratio of 3: 1, and water and the solvent were removed by distillation under reduced pressure.
100 g of isocyanurate type polyisocyanate (Duranate THA-100, manufactured by Asahi Kasei Corporation)
And 25 g of a mixture of methoxypolyethylene glycol obtained above and sodium dioctylsulfosuccinate were mixed, and a urethanization reaction was carried out at 90 ° C. for 8 hours. The obtained polyisocyanate is a pale yellow liquid, having an isocyanate group content of 15.3% and a weight average molecular weight of 100.
0 and the viscosity was 3500 mPa · s.

[0042]

The polyisocyanate composition having high emulsifiability according to the present invention is excellent in workability because the viscosity can be reduced, and is easily mixed with an aqueous emulsion to prepare a water-based coating composition. Can be stirred. Further, the polyisocyanate composition using the ionic activator suppresses the reaction between the isocyanate group and water in a water-dispersed state, so that a long pot life can be achieved when used in an aqueous coating composition.
Accordingly, it can be used as a coating material in which a solvent-based polyurethane coating material has been used conventionally, particularly as a coating material for repainting an architectural exterior, a coating material for automobile repair, or a plastic coating material. Furthermore, it can be applied to a wide range of fields such as sealing agents, adhesives, inks, coating materials, casting materials, elastomers, foam and plastic raw materials, and fiber treatment agents.

Continued on the front page F-term (reference) 4J002 AA05X AC00X AC02X AC07X AC08X BD05X BD10X BD12X BF02X BG03X CK02X CK04W EN136 EU046 EU116 EV186 EV256 FD316 GH01 GJ01 HA07 4J034 BA03 DA01 DB03 DB07 DN03 DP12 DP13 H03 DP02 HC08 HC17 HC18 HC22 HC35 HC52 HC61 HC71 JA13 JA42 QB19 QC05 RA07 RA08 4J038 DG131 DG251 DG261 DG301 KA09 MA08 MA10 NA04 NA26 NA27 PB02 PB05 PB07 PC02 PC04 PC06

Claims (3)

[Claims] 1. (a) 50 to 95% by weight of an isocyanate prepolymer obtained from an aliphatic and / or alicyclic diisocyanate and a monoalcohol having 1 to 50 carbon atoms, (b) having at least one hydroxyl group, A highly emulsifiable polyisocyanate composition characterized by reacting 5 to 50% by weight of a nonionic hydrophilic component composed of 3 to 50 ethylene oxide repeating units. 2. High emulsifiability characterized by comprising the polyisocyanate composition according to claim 1 and (c) 0.5 to 20% by weight of a water-free ionic surfactant. Polyisocyanate composition having. (A) a hydroxyl value of 1 to 300 mg KOH /
g of the aqueous emulsion and (B) the polyisocyanate composition according to claim 1 or 2 in an isocyanate group / hydroxyl group equivalent ratio of 0.5 to 5.0. Water-based coating composition.