JPH0621236B2 - Method for producing aqueous coating composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel method for producing an aqueous coating composition, wherein the aqueous coating composition is excellent in rust prevention, anticorrosion and anionic base material. On the other hand, it provides a paint exhibiting excellent performance.

[Conventional technology]

As a so-called non-soap type emulsion which does not conventionally use a surfactant, for anionic type, for example, a maleated polybutadiene neutralized product, a water-soluble alkyd resin,
A method for emulsion polymerization in the presence of a water-soluble acrylic resin or the like is provided.

[Problems to be Solved by the Invention]

However, as for the cationic type, at present, non-soap type emulsions have not been sufficiently studied.

[Means for Solving the Problems]

As a result of earnest research, the present invention is an aqueous coating composition which is a novel cationic non-soap emulsion having excellent adhesion to an anionic base material, corrosion resistance to metal materials, and high water resistance and chemical resistance. The invention of the product was completed.

That is, according to the present invention, an alkoxyl group or an alkoxyl group in the presence of an acid neutralized product of a copolymer of a vinyl monomer containing a tertiary amino group and another vinyl monomer is used without using a cationic surfactant. A monomer mixture of a silyl group-containing vinyl monomer substituted with an alkoxyalkoxyl group and another vinyl monomer copolymerizable therewith is emulsion-polymerized.

To further explain this in detail, in ordinary emulsion polymerization, anionic, nonionic or cationic surfactants are used to polymerize monomers in micelles formed by the surfactant molecules. However, deterioration of various properties such as water resistance and chemical resistance due to these surfactants cannot be avoided.

However, according to the present invention, an acid neutralized product of a copolymer of a cationic tertiary amino group-containing vinyl monomer and another vinyl monomer is used as a dispersion stabilizer without using a surfactant. Therefore, there is no adverse effect of the above-mentioned surfactant unlike ordinary emulsions.

Further, in the present invention, an alkoxyl group or a silyl group-containing vinyl monomer substituted with an alkoxyalkoxyl group is used, and an alkoxyl group or a silyl group substituted with an alkoxyalkoxyl group is an acid, a base or a metal. Is easily hydrolyzed by the catalytic action of to become a silanol group of Si—OR → SiO. This SiOH is very reactive and has the property of reacting promptly with the siloxane bonds of the same SiOOH or with the -OH group on the surface of the substance.

Next, the constitution of the aqueous coating composition of the present invention will be specifically described. First, (A) the above-mentioned tertiary amino group-containing vinyl monomer used in the copolymer of the cationic tertiary amino group-containing vinyl monomer used in the present invention and another vinyl monomer As for the body,
Examples thereof include vinyl monomers having a tertiary amino group such as N · N ′ dimethylaminoethyl (meth) acrylate, N · N′diethylaminoethyl (meth) acrylate, and vinylpyridine. Other vinyl monomers copolymerized with the tertiary amino group-containing vinyl monomer include C _{1 to} C ₁₈ alkanols such as methyl (meth) acrylate and ethyl (meth) acrylate, and unsaturated carboxylic acids. Ester, styrene, vinyltoluene, β-hydroxyethyl (meth) acrylate having a hydroxyl group as a monomer having a functional group, β-hydroxypropyl (meth) acrylate, polyethylene glycol (meth) acrylate, N-methylol acrylamide, etc. , Those having an oxirane ring, glycidyl (meth) acrylate, allyl glycidyl ether, those having an amide group, (meth) acrylamide, N. butoxy acrylamide, diacetone acrylamide, N. methylol acrylamide, carboxylic acid Examples include acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid.

The monomer mixture can be usually copolymerized by solution polymerization, but since it is neutralized with an acid to make it water-dispersible, a solvent for polymerization is methanol, ethanol, isopropyl alcohol, or the like. It is preferable to use hydrophilic solvents such as C _{1 to} C ₃ alcohols, ketones such as acetone and methyl ethyl ketone, and glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and ethylene glycol monobutyl ether. As the polymerization initiator, usual benzoyl peroxide, t-butyl peroxybenzoate,
Peroxides such as t-butylperoxy / 2-ethylhexanoate, azobisisobutyronitrile, 2 ・
2'Azobis2.4 dimethylvaleronitrile, 2.2
Azobis 4. An azo-based polymerization initiator such as methoxy-2,4-dimethylvaleronitrile can be used, but since a vinyl monomer containing a tertiary amino group is used in the present invention, an azo that does not decompose due to the alkalinity of the monomer. The use of a system polymerization initiator is preferred.

The copolymer of the tertiary amino group-containing vinyl monomer and other vinyl monomer thus polymerized is usually polymerized and then neutralized with an inorganic or organic acid such as hydrochloric acid, formic acid or acetic acid. It is cationic and water-dispersible, but it may be neutralized with the above-mentioned acid before the polymerization.

(B) The silyl group-containing vinyl monomer substituted with an alkoxyl group or alkoxyalkoxyl group used in the present invention, the formula _{CH 2: CHSi (OC 2 H} 5) 3 CH 2: CHSi (OCH 3) 3 CH _{2: C (CH 3) COOC} 3 H 6 Si (OCH 3) 3 CH 2: C (CH 3) COOC 3 H 6 Si (OC 2 H 4 OCH 3) 3 CH 2: CHCOOC 3 H 6 Si (OC 2 H ₄ OCH ₃ ) ₃ Silyl group-containing vinyl monomer substituted with an alkoxyl group or an alkoxyalkoxyl group such as NH ₂ C ₃ H ₆ Si (OC ₂ H ₅ ) ₃ NH ₂ CONHC ₃ H ₆ Si (OC ₂ H ₅ ) ₃ NH ₂ C ₂ H ₄ NHC ₃ H ₆ Si (OCH ₃ ) _{3 and the} like silane coupling agent having an amino group and a glycidyl monomer having a vinyl group and an oxirane ring in the same molecule, for example, Reaction with.

A reaction product with a silane compound having a mercapto group such as the above glycidyl monomer HSC ₃ H ₆ Si (OC ₂ H ₅ ) ₃ .

Examples thereof include vinyl monomers having a silyl group substituted with 1 to 3 alkoxyl groups, such as a reaction product of α-β unsaturated carboxylic acid.

The ratio of the alkoxyl group or the silyl group-containing vinyl monomer substituted with an alkoxyalkoxyl group in the water-dispersed composition is preferably 1 to 40% by weight, and if it is less than this, the various performances of the present invention are not satisfied. , If it is more than this, it is disadvantageous in terms of dispersion stability and cost.

(C) In the present invention, as the vinyl monomer copolymerizable with the above-mentioned (B), all vinyl monomers used in the synthesis of the copolymerization of (A) can be used.

In the present invention, the monomer mixture consisting of (B) and (C) is emulsion-polymerized in the presence of such (A), and a usual emulsion polymerization is applied as the polymerization method at this time. That is, deionized water is usually used, and potassium persulfate, ammonium persulfate, or 2.
2'-Azobis (2-aminodipropane) hydrochloride or the like can be used, and polymerization is carried out by applying a monomer dropping method, a monomer emulsion dropping method or the like.

〔Example〕

Example 1 Preparation of Tertiary Amino Group-Containing Copolymer Methyl Methacrylate 120 parts Butyl Acrylate 75 parts β-Hydroxyethyl Methacrylate 30 parts NN 'Dimethylaminoethyl Methacrylate 30 parts Isobutyl Methacrylate 45 parts 2.2' Azobis2.4 Dimethylvalero Nitrile 6 parts 150 parts of isopropyl alcohol was placed in a flask equipped with a stirrer and a condenser, and the temperature was adjusted to 80 under a nitrogen stream.
The temperature is raised to 0 ° C. and the mixture is added dropwise over 3 hours.

Then, a solution prepared by dissolving 1 part of 2.2 'azobis2.4 dimethylvaleronitrile in 50 parts of isopropyl alcohol was added 30 minutes, 60 minutes, and 180 minutes after completion of the dropping of the above mixture, and then added to 80 ° C. The copolymer solution obtained by reacting for 2 hours while holding the solution has a viscosity W, a nonvolatile content of 60% and a color number of 2
Met.

Example 2 Preparation of aqueous coating composition Styrene 54 parts 2 Ethylhexyl acrylate 50 parts γ Methacryloxypropyltrimethoxylane 5 parts Methyl methacrylate 35 parts Stearyl methacrylate 22 parts In one flask equipped with stirrer and cooler. 60 parts of the obtained tertiary amino group-containing copolymer, 250 parts of deionized water and 1 part of glacial acetic acid are charged and sufficiently stirred to homogenize the copolymer, and the temperature is raised after neutralizing the copolymer.

When the temperature reached 80 ° C., 20 parts of deionized water was added with 2.2 parts of 2.2′azobis (2amidinopropane) hydrochloride.
Add 5 parts melted. After 5 minutes, 30 parts of the above monomer mixture was charged and reacted for 10 minutes. After that, the remaining monomer mixture was added dropwise over 3 hours, and the mixture was held for 1 hour and then the processing was completed. The temperature is maintained at 80 ± 2 ° C during this reaction.

The aqueous coating composition thus obtained had a solid content of 40.
The residual monomer content was 1% and the viscosity was 6000 CPS, and the residual monomer content was 0.2% or less.

Example 3 Manufacture of aqueous coating composition Styrene 52 parts 2 Ethylhexyl acrylate 50 parts γ Methacryloxypropyltrimethoxylane 30 parts Methyl methacrylate 10 parts All the equipment and the like are the same as in Example 2, the third obtained in Example 1. 100 parts of primary amino group-containing copolymer, deionized water 24
Charge 3 parts and 1.7 parts of glacial acetic acid, heat to 80 ° C while neutralizing by stirring until uniform, and add 20 parts of deionized water.
Add 0.5 parts of 2.2 'azobis (2amidinopropane) hydrochloride dissolved therein. After 5 minutes, 30 parts of the above monomer mixture was charged and reacted for 10 minutes. After that, the remaining monomer mixture is added dropwise over 3 hours, and the mixture is held for 2 hours, and then the processing is completed.

The aqueous coating composition thus produced has a solids content of 4
0.5%, viscosity 5500 CPS and residual monomer 0.5%
It was below.

Comparative Example 1 Production of Aqueous Coating Composition Not Containing Alkoxysilyl Group All were produced under the same conditions except that 5 parts of γ-methacryloxypropyltrimethoxysilane in Example 2 was changed to isobutyl methacrylate.

The produced aqueous coating composition had a solid content of 40.6% and a viscosity of 1
It was 500 CPS.

Comparative Example 2 Production of General Cationic Emulsion Copolymer Using Surfactant 148 parts of deionized water and Catiogen L (quaternary ammonium salt manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) were added to the same apparatus as in Example 2.
Part is charged and the temperature is raised to 80 ° C. Separately, 102 parts of deionized water, 50 parts of styrene, 70 parts of methyl methacrylate, 76 parts of 2-ethylhexyl acrylate, 4 parts of acrylamide, 5 parts of cationogen L, 0.5 part of 2.2 'azobis (2 amidinopropane) hydrochloride. Then, prepare an emulsion of the monomer with a homomixer.

When the temperature reached 80 ° C., 0.5 parts of 2.2 ′ azobis (2amidinopropane) hydrochloride dissolved in 10 parts of deionized water was added, and after 10 minutes, the emulsified monomer mixture was added for 3 hours. Drop it and hold for 2 hours, then finish. Solid content of emulsion 42.3%, viscosity 100
It was 00 CPS.

Comparative Example 3 Production of General Anionic Emulsion Copolymer Using Surfactant The same apparatus as in Example 2 was charged with 148 parts of deionized water and 1 part of sodium dodecylbenzenesulfonate and heated to 80 ° C. When the temperature reaches 80 ° C., 0.5 part of ammonium persulfate is added. Separately, 100 parts of styrene,
5 parts of acrylamide, 4 parts of acrylic acid, 16 parts of methyl methacrylate, 75 parts of 2 ethylhexyl acrylate,
A mixture prepared by charging 0.5 parts of ammonium persulfate, 1 part of sodium dodecylbenzenesulfonate and 112 parts of deionized water and emulsifying the monomer with a homomixer was prepared, and after 5 minutes, 32 parts of this was added, and further. After 10 minutes, the remaining emulsified monomer mixture is added dropwise over 3 hours and kept for 2 hours. Produced anion emulsion solids 44.1
%, The viscosity was 6000 CPS.

Various physical property comparison test examples Test example 1 The test results of the properties of Examples 2 and 3 and Comparative examples 1, 2 and 3 are shown.

Test example 2 What was apply | coated on the flexible asbestos slate board and dried for 20 days at 20 degreeC and a humidity of 65% shows adhesiveness and water resistance at room temperature water immersion for 96 hours.

It shows the alkali resistance of what was immersed in an alkaline water (sodium hydroxide) of PH10 for 96 hours.

The adhesion was tested with a surf bond tester, and 6 kg / cm ² <is a value that cannot be measured because cohesive failure of the asbestos slate plate itself occurs.

◎ No abnormality at all 〇 Almost no abnormality □ A little abnormality △ Considerable abnormality Consideration Considering the results of Test Examples 1 and 2, the aqueous coating composition according to the present invention, which does not use the emulsifier, forms a film at a low temperature. It has excellent properties and gloss, and since it is a type that cures after drying, it has excellent water resistance and alkali resistance. In addition, it exhibits excellent adhesion due to a strong adhesive force due to a chemical bond with an alkali base material.

Front page continuation (72) Inventor Hironori Hata 18 Ichigayama, Uchikoshi, Miyoshi-cho, Nishikamo-gun, Aichi Natco Paint Co., Ltd./Miyoshi Plant

Claims (1)

[Claims] 1. An acid neutralized product of a copolymer of (A) a tertiary amino group-containing vinyl monomer and another vinyl monomer in an amount of from 5% by weight to 50% by weight.
1% to 40% by weight of (B) an alkoxyl group or a silyl group-containing vinyl monomer substituted with an alkoxyalkoxyl group in the presence of 1% by weight, and another vinyl copolymerizable with (C) and (B). A method for producing an aqueous coating composition, which comprises emulsion-polymerizing a monomer mixture containing 94% by weight to 10% by weight of a monomer in water.