JPH02229820A - Composition resin dispersion - Google Patents

Abstract

PURPOSE:To obtain the title dispersion having excellent storage stability and curing properties by copolymerizing specific two kinds of polymerizable unsaturated resins with a polymerizable monomer and optionally an unsaturated monomer to give a graft polymer, neutralizing the graft polymer with a base and dispersing the polymer into water. CONSTITUTION:(A) A polymerizable unsaturated resin to which a polymerizable unsaturated group is introduced, which is obtained by adding a polymerizable unsaturated monomer containing carboxyl or epoxy having reactivity with a functional group of a carboxyl or epoxy-containing polymerizable unsaturated monomer copolymer to the copolymer is copolymerized with (B) a polymerizable unsaturated monomer containing epoxy or carboxyl having reactivity with carboxyl or epoxy of the component A, optionally (C) an unsaturated monomer copolymerizable with the components A and B, a polymerization initiator and an organic solvent to give a graft polymer having 20-200 acid value and 200-5,000 epoxy equivalent. Then the polymer is neutralized with a base and dispersed into water to give the aimed dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an aqueous resin dispersion of a copolymer having carboxyl groups and epoxy groups.

(Prior art and its problems) Conventionally, a mixture of a polymer having a carboxyl group and a polyfunctional epoxy compound, or a mixture of a polymer having a handboxyl group and a polyfunctional carboxyl compound has been used for powder coatings. Although it is known that it can be cured by heating, water-based compositions in which a polymer or compound having a carboxyl group and a polymer or compound having an epoxy group coexist in water have problems with curability and stability and are not practical. has not been standardized. For example, in a composition in which an epoxy group-containing resin is dispersed in water in the presence of a surfactant, and a carboxyl group-containing resin is neutralized with a base and dispersed in water, the two are sufficiently fused during curing. If this is not done properly, the curing properties will be insufficient. Furthermore, a mixture of a water-soluble epoxy resin and a resin solution in which carboxyl groups are neutralized and water-solubilized with a base has a problem of poor storage stability and gelation within a few days.

(Means for Solving the Problems) The present inventors have conducted intensive research to obtain a water-based fat composition that utilizes the curing reaction between an epoxy group and a carboxyl group and is free from the above-mentioned problems. , [I] A polymerizable unsaturated resin having a carboxyl group, an epoxy group-containing unsaturated monomer, and, if necessary, another copolymerizable unsaturated monomer having a specific acid value and epoxy equivalent. A graft polymer, or [II] A polymerizable unsaturated resin having an epoxy group, an unsaturated heptanomer containing a carboxyl group, and, if necessary, a specific acid value obtained by copolymerizing other copolymerizable unsaturated monomers. A neutralized, water-dispersed dispersion of a graft polymer having an epoxy equivalent and an epoxy equivalent surprisingly shows excellent storage stability,
In addition, the inventors discovered that the coating exhibits excellent curability after coating, leading to the completion of the present invention.

That is, the present invention provides (A) a copolymer of a polymerizable unsaturated monomer having a carboxyl group or a copolymer of a polymerizable unsaturated monomer having an epoxy group, with reactivity with the functional group of the copolymer. A polymerizable unsaturated resin having a carboxyl group or an epoxy group, which is obtained by adding a polymerizable unsaturated monomer containing a functional group selected from a carboxyl group and an epoxy group to introduce a polymerizable unsaturated group, B) A polymerizable monomer containing a functional group selected from an epoxy group and a carboxyl group that is reactive with the carboxyl group or epoxy group possessed by the polymerizable unsaturated resin (A), and optionally (C) the resin ( A) and a polymerizable monomer CB) obtained by copolymerizing an unsaturated monomer copolymerizable with an acid value of 20 to 200 and an epoxy equivalent of 200.
The present invention provides an aqueous resin dispersion obtained by neutralizing a graft polymer of 5000 to 5,000 with a base and dispersing it in water.

In the present invention, the copolymer used for producing the polymerizable unsaturated resin (A) may have a carboxyl group or an epoxy group as a functional group. When using a copolymer having a carboxyl group, [I] (A-1) A polymerizable unsaturated monomer containing an epoxy group is added to a copolymer of a polymerizable unsaturated monomer having a carboxyl group. A carboxyl group-containing polymerizable unsaturated resin into which a polymerizable unsaturated group has been introduced, (B-1) an epoxy group-containing polymerizable monomer, and optionally (C-1) a resin (A-1) and a monomer (B-1). Regarding an aqueous resin dispersion obtained by neutralizing with a base a graft polymer having an acid value of 20 to 200 and an epoxy equivalent of 200 to 5,000 obtained by copolymerizing an unsaturated monomer copolymerizable with -1) and dispersing it in water. , In addition, when the copolymer used for producing the resin (A) has an epoxy group, [II] (A-2) The copolymer of a polymerizable unsaturated monomer having an epoxy group contains a carboxyl group. An epoxy group-containing polymerizable unsaturated resin obtained by adding a polymerizable unsaturated monomer to introduce a polymerizable unsaturated group, (B-2) a carboxyl group-containing unsaturated monomer, and optionally (C-2) (A-2) A graft polymer having an acid value of 20 to 200 and an epoxy equivalent of 200 to 5,000 obtained by copolymerizing an unsaturated monomer copolymerizable with the resin and (B-2) monomer is neutralized with a base, This invention relates to an aqueous resin dispersion obtained by water dispersion.

First, the case [I] above will be explained.

The copolymer of a polymerizable unsaturated monomer having a carboxyl group used in the production of the polymerizable unsaturated resin (A-1) can be copolymerized with a polymerizable unsaturated monomer having a carboxyl group and this monomer. It is a copolymer with a monomer. As polymerizable unsaturated monomers having a carboxyl group, mecacrylic acid and acrylic acid are generally used, but other examples include maleic acid, fumaric acid, itaconic acid, crotonic acid, (meth)acrylic acid, and ε monobrolactone. Additives such as can also be used. Examples of monomers copolymerizable with these monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl (meth)acrylate, 2- Alkyl (meth)acrylates having 1 to 18 carbon atoms such as ethylhexyl (meth)acrylate and lauryl (meth)acrylate; Saturated monomer; styrene, α-methylstyrene, vinyltoluene, vinyl acetate, (meth)
Monomers such as acrylamide, (meth)acrylonitrile, and N-methylol(meth)acrylamide butyl ether can be mentioned.

Examples of the manufacturing method include a method in which monomer components are polymerized in the presence of a polymerization catalyst and preferably an organic solvent.

It is desirable that the copolymer obtained as described above has two or more carboxyl groups, preferably 5 to 50 carboxyl groups in one molecule, and the number average molecular weight of the copolymer is 100.
It is preferably within the range of 0 to 50,000, and 300
More preferably, it is within the range of 0 to 30,000.

Examples of the polymerizable unsaturated monomer containing an epoxy group to be added to the above copolymer to introduce a polymerizable unsaturated group include glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, and 3,4-epoxycyclohexylmethyl. Examples include methacrylate, 3,4-epoxycyclohexylmethyl acrylate, and the like.

In order to obtain a polymerizable unsaturated resin (A-1) by adding the above polymerizable unsaturated monomer containing an epoxy group to the copolymer of the above polymerizable unsaturated monomer having a carboxyl group, both The mixture is heated at 50 to 150°C in the presence of an organic solvent and a polymerization inhibitor such as hydroquinone if necessary.
, more preferably, the reaction may be carried out at 50 to 120° C. for about 30 minutes to 2 hours, and it is preferable to carry out the reaction until all the epoxy groups have reacted with the carboxyl groups. In this reaction, it is necessary that the amount of epoxy groups is smaller than the amount of carboxyl groups, and the carboxyl groups that remain unreacted neutralize the graft polymer that is finally obtained, and when mixed with water, it becomes water-dispersible. It is necessary to have as much as possible. The addition reaction between a carboxyl group and an epoxy group can be monitored by measuring the acid value.

The amount of polymerizable unsaturated groups introduced by the addition reaction is preferably 0.2 to 3.0, more preferably 0.5 to 1.5 per molecule.

The carboxyl group-containing polymerizable unsaturated resin (A-1) obtained as described above is then mixed with the epoxy group-containing polymerizable monomer (B-1) and, if necessary, the resin (A-1).
) and an unsaturated monomer (C-1) copolymerizable with monomer C B-1) to obtain a graft polymer having a carboxyl group and an epoxy group.

Examples of the monomer (B-1) include glycidyl mequaacrylate, glycidyl acrylate, allyl glycidyl ether, 3,4-epoxy hexyl methyl methacrylate, 3,4-epoxy hexyl methyl acrylate, and the like. Among these, monomers having an alicyclic epoxy group, such as the following formula (I) Rh
A compound represented by o (wherein R+ represents a hydrogen atom or a methyl group) is particularly preferred from the viewpoint of storage stability and curability of the aqueous resin composition obtained.

Copolymerization methods for producing graft polymers include (
Examples include a method of copolymerizing a mixture of A-1), (B-1), and optionally (C-1) in the presence of a polymerization catalyst and preferably an organic solvent.

The polymerization temperature at this time is 100°C or less, more preferably 8°C or less.
It is desirable that the temperature is 0°C or lower. It is not preferable for the polymerization temperature to exceed 100° C., since addition reactions between carboxyl groups and epoxy groups are likely to occur during polymerization. As the polymerization initiator used for copolymerization, any initiator that generates radicals at the polymerization temperature can be used, such as azobisisobutyronitrile, azobisdimethylbaretonitrile, and azobiscyclohexane luponitrile. , benzoyl peroxide, t-butylbenzoate, acetyl peroxide, t-butyl 2-ethylhexanoate, lauroyl peroxide, bis(4-t-
Examples include butylcyclohexyl)peroxydicarbonate, and among these, azobisdimethylbaretonitrile and bis(4-t-butylcyclohexyl)baroxydicarbonate are particularly preferred.

The graft polymer obtained as described above can be used as it is dissolved in an organic solvent or diluted with an organic solvent, but in the present invention, the graft polymer is then neutralized with a base and dispersed in water. be converted into The graft polymer has an acid value of 20 in terms of water dispersibility and curability.
~200, preferably 50-120, epoxy equivalent 20
0 to 5000, preferably 300 to 2500. Further, the number average molecular weight of the graft polymer is preferably in the range of ●000 to ioooooo.

Examples of the base used to neutralize the graft polymer include triethylamine, dimethylaminoethanol, methyldiethanolamine, tributylamine, and ammonia. The neutralization equivalent may be selected appropriately, but it is usually 0.
．． The range is 1-1.2 equivalents. The graft polymer can be easily dispersed in water by simultaneously neutralizing the graft polymer with a base or by mixing and stirring the graft polymer with water after neutralization, and the desired aqueous resin dispersion can be obtained.

Next, the case [■] above will be explained. The copolymer of a polymerizable unsaturated heptanomer having an epoxy group used in the production of the polymerizable unsaturated resin (A-2) is a copolymer of a polymerizable unsaturated heptanomer having an epoxy group and this monomer. It is a copolymer with copolymerizable monomers. Examples of the polymerizable unsaturated monomer having an epoxy group include glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, 3,4-epoxycyclohexylmethyl methacrylate, and 3,4-epoxycyclohexylmethyl acrylate. Monomers that can be copolymerized with these monomers include monomers that can be copolymerized with a polymerizable unsaturated monomer having a carboxyl group in the copolymer used for producing the polymerizable unsaturated resin (A-1). monomers can be used.

The copolymer can be manufactured by the same method as the method for manufacturing the copolymer used for manufacturing the polymerizable unsaturated resin (A-1).

It is desirable that the copolymer obtained as described above has two or more epoxy groups in one molecule, preferably 5 to 50 epoxy groups, and the number average molecular weight of the copolymer is 1000 to
Preferably within the range of 100,000, 300
More preferably, it is within the range of 0 to 30,000.

The polymerizable unsaturated monomer containing a carboxyl group that is added to the above copolymer to introduce a polymerizable unsaturated group is generally acrylic acid or methacrylic acid, but other examples include maleic acid and fumaric acid. Acids such as itaconic acid, crotonic acid, and adducts of (meth)acrylic acid and ε-cabrolactone can also be used.

In order to obtain a polymerizable unsaturated resin (A-2) by adding the above polymerizable unsaturated monomer containing a carboxyl group to the copolymer of the above polymerizable unsaturated monomer having an epoxy group, both The mixture is heated at 50 to 150°C in the presence of an organic solvent and a polymerization inhibitor such as hydroquinone if necessary.
The reaction may be carried out for about 30 minutes to 8 hours, and it is preferable to carry out the reaction until all the carboxyl groups have reacted with the epoxy groups. In this reaction, it is necessary that the amount of carboxylic groups is less than the amount of epoxy groups.

The amount of polymerizable unsaturated groups introduced by the addition reaction is 0
．． The number is 2 to 3.0, more preferably 0.5 to 1.5.

The epoxy group-containing polymerizable unsaturated resin (A-2) obtained as described above is then added to the carboxyl group-containing polymerizable monomer (B-2) and, if necessary, the resin (A-2).
It is copolymerized with an unsaturated monomer (C-2) copolymerizable with the monomer (B-2) to obtain a graft polymer having a carboxyl group and an epoxy group.

Examples of the monomer (B-2) include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, and an adduct of (meth)acrylic acid and ε-cabrolactone.

As a copolymerization method for producing graft polymers. (
Examples include a method of polymerizing a mixture of A-2), (B-2), and optionally (C-2) in the presence of a polymerization catalyst and preferably an organic solvent. The polymerization temperature at this time was 10
It is desirable that the temperature be 0°C or lower, more preferably 80°C or lower.

The graft polymer obtained as above has an acid value of 20
~200, epoxy equivalent is required to be 200 to 5000, and number average molecular weight is 1000 to 100000.
It is preferable that it is in the range of .

This product is then neutralized and water-dispersed in the same manner as in [I] to obtain an aqueous resin dispersion.

The aqueous resin dispersion of the present invention may contain organic solvents, pigments, paint additives such as antifoaming agents and leveling agents, and the like, if necessary.

(Actions and Effects of the Invention) The aqueous resin dispersion of the present invention has excellent storage stability and curability, and after being applied to the object to be coated, it is crosslinked and cured by heating at 100 to 180°C for about 10 to 30 minutes, resulting in a smooth and smooth surface. A coating film with excellent alkali resistance is formed. When an amine is used for neutralization during this heat curing, the amine acts as a reaction catalyst between the epoxy group and the carboxyl group.

The reason why the aqueous resin dispersion of the present invention has good storage stability and excellent curability is not clear, but the reason is that many carboxyl groups exist on the surface of the water-dispersed resin particles, and There are many epoxy groups in the resin, resulting in a structure in which carboxyl groups and epoxy groups are separated, resulting in good storage stability.In addition, as the resin particles are melted by heating, the epoxy groups and carboxyl groups in the same resin are It is thought that the curability is excellent because the opportunity for contact with the group increases and the reaction occurs. Further, when an amine is used as a neutralizing agent, the amine acting as a neutralizing agent acts as a curing catalyst, which is also a reason for the excellent curability.

(Example) The present invention will be explained in more detail with reference to an example. In addition, hereinafter, "part" and "r%" mean "part by weight" and "wt%", respectively. Example l 7.2 parts of acrylic acid and n-in the presence of 66.7 parts of ethylene glycol monobutyl ether and a polymerization initiator
3.6 parts of chrycidyl methacrylate was added to 166.7 parts of a carboxyl group-containing vinyl copolymer solution with a solid content of 60% and a number average molecular weight of about 15,000 obtained by copolymerizing 92.8 parts of butyl methacrylate. The mixture was added and reacted at 120°C until the resin acid value reached 42. This reaction product solution 1
70.3 parts, 3.4-epoxycyclohexylmethyl methacrylate 22.4 parts, n-butyl methacrylate}-77.6 parts, azobisdimethylvaleronitrile 0.
5 parts of the mixture was heated at 80° C. to copolymerize to obtain a graft polymer solution. The obtained graft polymer had an acid value of 20.4, an epoxy equivalent of 2000, and a number average molecular weight of 28.
It was 000.

15 parts of triethylamine was blended with 266.8 parts of the obtained graft polymer solution, and deionized water was added while stirring to perform water dispersion, resulting in a non-volatile content of 40% and a Gardner viscosity of H.
(25°C) an aqueous resin dispersion was obtained.

Example 2 Solid content 70% obtained by copolymerizing 14.2 parts of glycidyl methacrylate and 85.8 parts of methyl methacrylate in the presence of 42.9 parts of isobrobanol and a polymerization initiator.
0.72 parts of acrylic acid was added to 142.9 parts of an epoxy group-containing vinyl copolymer solution having a number average molecular weight of about 20,000, and the mixture was reacted at 120° C. until the acid value reached 0. 145.05 parts of this reaction product solution, 14.4 parts of acrylic acid,
85.6 parts of methyl methacrylate and bis(4-t
-butylcyclohexyl) baroxydicarbonate 1
A mixture of the above components was heated at 70° C. to copolymerize to obtain a graft polymer solution. The obtained graft polymer had an acid value of 81, an epoxy equivalent of 2200, and a number average molecular weight of 4 g000.
Met.

10 parts of triethylamine was blended with 245.05 parts of the obtained graft polymer solution, and deionized water was added while stirring to perform water dispersion, to obtain an aqueous resin dispersion with a nonvolatile content of 40% and a Gardner viscosity R (25°C). Ta.

Example 3 14.4 parts of acrylic acid, 74.0 parts of n-butylmequaacrylate, 11.0 parts of 2-hydroxyethyl acrylate in the presence of 42.9 parts of n-propanol and a polymerization initiator.
Solid content 70% obtained by copolymerizing 6 parts, number average molecular weight approximately 5
000 carboxyl group-containing vinyl copolymer solution 142
．． 1.4 parts of glycidyl methacrylate was added to 9 parts, and the mixture was reacted at 120°C until the acid value reached 106. A mixture of 144.3 parts of this reaction product solution, 200 parts of 3,4-epoxycyclohexylmethyl methacrylate, and 10 parts of azobisdimethylbenzene nitrile was heated at 80° C. and polymerized to obtain a graft polymer solution. The obtained graft polymer had an acid value of 35, an epoxy equivalent of 306, and a number average molecular weight of 36,000.

30 parts of methyldiethanolamine was blended into 344.3 parts of the obtained graft polymer solution, and deionized water was added while stirring to perform water dispersion to obtain an aqueous resin dispersion with a nonvolatile content of 40% and a Gardner viscosity of P. .

Comparative Example 1 50 parts of the carboxyl group-containing vinyl copolymer solution with a solid content of 60% used in Example 1 and 7 parts of the solid content used in Example 2
0% epoxy group-containing vinyl copolymer solution, 1.5 parts of dimethylaminoethanol was added to this mixture, and after mixing, deionized water was added and stirred uniformly. An aqueous resin dispersion having a viscosity (25° C.) of A was obtained.

The aqueous resin dispersions obtained in Examples and Comparative Examples were each applied to a glass plate to a dry film thickness of 30 microns.
The film performance was tested by baking at 40° C. for 30 minutes.

Furthermore, the storage stability of each aqueous resin dispersion was also tested. The results of these tests are shown in Table 1.

[Test method] The test methods in Table 1 are as follows.

Painted surface condition: Visually evaluated, and those with no abnormalities were rated ○.

Gel fraction: After peeling off the baked coating from the glass plate, its free ID
The i membrane was immersed in acetone under reflux conditions at about 57°C for 4 hours, and the value was determined from the following formula.

Coating film weight after immersion Gel fraction (%) = XIOO Coating film weight before immersion Alkali resistance: A spot test was conducted by contacting the coating film on a glass plate with a 10% caustic soda aqueous solution.

The contact of lO% caustic soda aqueous solution is The test was carried out at 20°C for 24 hours.

Those with no change were designated as O.

Storage stability: 150 g of each of the aqueous resin dispersions obtained in Examples and Comparative Examples were placed in a sealed container with an internal volume of 250 cc, and stored at 20°C for 1 month and 6 months to examine changes due to storage. .

Claims (1)

[Claims] 1. (A) A copolymer of a polymerizable unsaturated monomer having a carboxyl group or a copolymer of a polymerizable unsaturated monomer having an epoxy group, and a functional group of the copolymer. A polymerizable unsaturated resin having a carboxyl group or an epoxy group, which is obtained by adding a reactive polymerizable unsaturated monomer containing a functional group selected from a carboxyl group and an epoxy group to introduce a polymerizable unsaturated group. , (B) a polymerizable monomer containing a functional group selected from an epoxy group and a carboxyl group, which is reactive with the carboxyl group or epoxy group possessed by the polymerizable unsaturated resin (A), and optionally (C ) An acid value of 20 to 200 and an epoxy equivalent of 200 to 5000 obtained by copolymerizing an unsaturated monomer copolymerizable with the resin (A) and the polymerizable monomer (B).
An aqueous resin dispersion obtained by neutralizing the graft polymer with a base and dispersing it in water. 2. The polymerizable unsaturated monomer having an epoxy group in the copolymer of a polymerizable unsaturated monomer having an epoxy group used in the production of resin (A) has the following formula (I) ▲ Numerical formula, chemical formula, table, etc. The aqueous resin dispersion according to claim 1, which is a compound represented by ▼(I) (wherein R_1 represents a hydrogen atom or a methyl group). 3. A claim in which the polymerizable monomer (B) is a compound represented by the following formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (wherein R_1 represents a hydrogen atom or a methyl group) 1. The aqueous resin dispersion according to 1.