JPH08157775A - Air drying aqueous coating material - Google Patents

Abstract

PURPOSE: To obtain an air drying aq. coating material having excellent weather resistance, water resistance, durability and other properties by adding a particular crosslinking agent to a dispersion of a carboxyl-contg. copolymer in water and further incorporating a dispersion of an alkoxysilyl-contg. copolymer in water. CONSTITUTION: An air drying aq. coating material comprising: (A) a dispersion of a carbonly-contg. copolymer in water; and (B) a crosslinking gent of a dihydrazide compd. represented by the formula (wherein n<=8) in an amt. of 0.01 to 2mol per mol of the carbonyl group; and (C) a dispersion of an alkoxysilyl-contg. copolymer in water, the amt. of the component (C) being 0.5 to 50 pts.wt. (solid content) based on 100 pts.wt. solid content of the carbonyl-contg. copolymer dispersion as the component (A). The dispersion of a carbonyl-contg. copolymer in water as the component (A) is pref. the one prepd. by emulsion polymn. of a mixture of 0.1 to 30wt.% carbonyl-contg. monomer, 0 to 10wt.% monomer, such as a monoolefinically unsatd. carboxylic acid, and 60 to 99.9wt.% monomer, such as a vinyl arom, compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-borne paint for normal temperature drying. In particular, the present paint relates to a water-borne paint for room temperature drying, which can omit the sealer painting step and is suitable for painting building interiors and exteriors that require moisture permeability, weather resistance, water resistance, durability, etc. .

[0002]

2. Description of the Related Art Generally, an aqueous dispersion of an acrylic copolymer has been used for a water-borne paint for drying at room temperature (hereinafter referred to as a water-borne paint for normal drying). Aqueous dispersions of acrylic copolymers require fusion of emulsion particles during film formation after coating. Therefore, it is difficult to increase the Tg (glass transition temperature) of the resin in the acrylic copolymer used for the water-based coating composition for constant drying due to its film-forming property, and therefore the stain resistance is lowered, and The fragility of water resistance cannot be denied. Further, when applied to cement-based materials, solvent-based and water-based sealers are required in terms of adhesion. On the other hand, the market tends to require shortening of processes and functionalization year by year, and there is a sealerless function as a required function, and further, the moisture permeability, elasticity, elasticity,
There is also an increasing need to improve toughness, durability and stain resistance. Conventionally, as a sealer-less type, there is a permanent drying coating that uses a special modified acrylic copolymer emulsion (introducing a siloxane group), but this one has a secondary adhesion after cementing with a cement-based material that is slightly non-sticky. There is a sufficient situation.

[0003]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems in the water-based paint for constant drying, and as a result, have found that the fragility of the water-based emulsion paint during film formation has a relatively high molecular weight. If it is reinforced with a small cross-linking agent and is used together with an aqueous dispersion of an alkoxysilyl group-containing copolymer, it does not reduce the original weather resistance of acrylic paints, sealerlessness, moisture permeability, water resistance, elasticity and resistance. It was found that an aqueous coating for constant drying, which has excellent stain resistance and durability, can be obtained,
The present invention has been completed.

The present invention provides "1. An aqueous dispersion of a carbonyl group-containing copolymer (A),
As a cross-linking agent, a dihydrazide compound (B) represented by the following formula is added in an amount of 0.01 to 2 per 1 mol of the carbonyl group.
0.5 to 50 parts by weight of the alkoxysilyl group-containing copolymer aqueous dispersion (C) is added to 100 parts by weight of the solid content of the carbonyl group-containing copolymer aqueous dispersion (A). (Dry solid) Waterborne paint for normal drying. _{H 2 N-NH-CO- (} C n H 2n) -CO-NH-N
H ₂ (n ≦ 8) 2. The carbonyl group-containing copolymer aqueous dispersion (A) is
(A) 0.1 to 30% by weight of a polymerizable carbonyl group-containing monomer having at least one carbonyl group in one molecule, (b) monoolefinic unsaturated having 3 to 5 carbon atoms. Carboxylic acid, unsaturated carboxylic acid amide, N-alkyl and / or N of the unsaturated carboxylic acid amide
0-10% by weight of a monomer selected from the group consisting of alkylol derivatives and mono-olefinically unsaturated carboxylic acids,
And (c) vinyl aromatic compound, n-alkyl ester of acrylic acid having 1 to 8 carbon atoms, n-alkyl ester of methacrylic acid having 1 to 8 carbon atoms, vinyl ester of saturated carboxylic acid, 1,3- In the presence of a dispersant, a monomer mixture containing 60 to 99.9% by weight of a monomer selected from the group consisting of diene, tert-butyl acrylate, vinyl halide, ethylene, acrylonitrile and methacrylonitrile. The aqueous coating composition for room temperature drying according to item 1, which is a copolymer dispersion obtained by emulsion polymerization in step (1). 3. The monomer (a) is diacetone acrylamide and / or diacetone methacrylamide,
Aqueous paint for normal temperature drying according to item 1 or 2. 4. Alkoxysilyl group-containing copolymer aqueous dispersion (c)
However, a copolymer having an acid group obtained by solution polymerization of an alkoxysilyl group vinyl monomer with another monomer containing an acid group-containing unsaturated monomer is neutralized with an amine compound and dispersed in water. The aqueous coating composition for room temperature drying according to any one of items 1 to 3, which is a copolymer dispersion formed by the above process. Regarding

[0005]

The carbonyl group-containing copolymer aqueous dispersion (A) used in the present invention contains (a) a polymerizable carbonyl group-containing monomer having at least one carbonyl group in one molecule. 1 to 30% by weight, (b) mono-olefinically unsaturated carboxylic acid having 3 to 5 carbon atoms, unsaturated carboxylic acid amide, N-alkyl and / or N-alkyl of the unsaturated carboxylic acid amide Roll derivative,
0 to 10% by weight of a monomer selected from the group consisting of monoolefinic unsaturated carboxylic acids, and (c) vinyl aromatic compounds, n-alkyl esters of acrylic acid having 1 to 8 carbon atoms, and methacrylic acid. N-alkyl ester having 1 to 8 carbon atoms, vinyl ester of saturated carboxylic acid, 1,3
60 to 99.9% by weight of a monomer selected from the group consisting of dienes, tert-butyl acrylate, vinyl halides, ethylene, acrylonitrile and methacrylonitrile.
It can be easily obtained by emulsion polymerization of the contained monomer mixture in the presence of a dispersant.

As the monomer (a), a monomer having a polymerizable double bond having at least one carbonyl group in one molecule is used. Specific examples of the monomer (a) include acrolein, diacetone acrylamide, diacetone methacrylamide, formylstyrene,
Vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) and the like can be mentioned. Particularly preferred are diacetone acrylamide and diacetone methacrylamide.

The cross-linking agent used in the present invention is a dihydrazide compound (B) represented by the following formula, n is preferably 1 to 6, and particularly preferably adipic acid dihydrazide of n = 4. _{H 2 N-NH-CO- (} C n H 2n) -CO-NH-N
H ₂ (n ≦ 8) In the present invention, the ratio of the carbonyl group-containing copolymer aqueous dispersion (A) to the crosslinker dihydrazide compound (B) is such that the carbonyl group 1 contained in the copolymer aqueous dispersion is 1%. The proportion of the hydrazide compound is 0.01 to 2 mol, preferably 0.05 to 1 mol, based on mol. If it is less than 0.01 mol, the brittleness during film formation cannot be improved, and if it is more than 2 mol, the crosslinking effect is not further improved.

In the present invention, the most preferable resin component containing (A) and (B) is JP-A-4-249.
No. 587. Specifically, the alkoxysilyl group-containing copolymer aqueous dispersion (c) used in the present invention can be produced as follows. The alkoxysilyl group-containing vinyl monomer is replaced with another unsaturated monomer which essentially requires an unsaturated monomer having an acid group, for example (meth)
Acrylic acid, alkyl ester of (meth) acrylic acid,
It is obtained by neutralizing a copolymer having an acid group, which is obtained by solution polymerization with a vinyl monomer such as (meth) acrylamide, styrene and vinyltoluene, with an amine compound or the like, and dispersing in water. Particularly preferable in this method is the aqueous dispersion of the alkoxysilyl group-containing copolymer described in JP-A-5-25354. It can also be produced by emulsion polymerization using an emulsifier. In this method, in order to stabilize the functional group of the alkoxysilyl group as a silanol group in an aqueous solution, the alkoxysiluri group is dispersed in the shell part of the emulsion to prevent contact between the silanol groups due to steric hindrance. It is essential to lower it.

Specific examples of the alkoxysilyl group-containing vinyl monomer or polymerizable oligomer used in the production of the above-mentioned aqueous dispersion of the alkoxysilyl group-containing copolymer include vinylsilane (eg vinylmethyldimethoxysilane, vinyltrimethoxysilane, Vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, etc.); (meth) acryloxyalkylsilane (eg,
γ-methacryloxypropyltrimethoxysilane, γ-
Methacryloxypropylmethyldimethoxysilane, γ-
(Acryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropyltriethoxysilane, etc.); a polymerizable oligomer having an alkoxysilyl group; (for example, one or more vinyl groups and alkoxysilyl groups) Polyurethane oligomer, polyether oligomer, polyamide oligomer, epoxy oligomer, polyester oligomer, etc.

In the present invention, the compounding ratio of the carbonyl group-containing copolymer aqueous dispersion (A) and the alkoxysilyl group-containing copolymer aqueous dispersion (C) is the carbonyl group-containing copolymer aqueous dispersion (A). 0.5 to 5 relative to 100 parts by weight of solid content of
It is 0 part by weight, preferably 2 to 20 parts by weight. If it is less than 0.5 part by weight, the adhesion to the cement-based substrate is poor.
If it exceeds 50 parts by weight, the stain resistance and elasticity are lowered and the cost is increased.

In the present invention, the carbonyl group at the polymer molecule end of the carbonyl group-containing copolymer aqueous dispersion (A) and the dihydrazide compound (B) having a relatively low molecular weight react with each other during film formation, resulting in elasticity, toughness, Provides a coating film with excellent weather resistance. At the same time, the alkoxysilyl group or silanol group in the aqueous dispersion of alkoxysilyl group-containing copolymer (C) condenses during film formation to form a siloxane bond, resulting in adhesion to the cement substrate and water resistance of film formation. And improve the moisture permeability. In producing the water-based paint of the present invention,
Appropriately pigments, fillers, aggregates, pigment dispersants, wetting agents, thickeners, defoamers, plasticizers, film-forming aids, organic solvents, preservatives, mildew-proofing agents, pH adjusting agents, rust-preventive agents Etc. can be selected and combined according to each purpose, and can be performed by a usual method.

The water-based paint of the present invention can be applied without a sealer, and is excellent in weather resistance, moisture permeability, water resistance, elasticity, toughness, stain resistance, and durability. Suitable for painting.

[0013]

EXAMPLES The present invention will now be described in more detail by way of examples.

Production of Aqueous Dispersion of Copolymer Containing Carbonyl Group Production Example 1 312 parts by weight of deionized water and 2.3 parts by weight of Newcol 707SF (manufactured by Nippon Emulsifier, solid content 30% by weight) in a 2-liter four-necked flask. Was added and after nitrogen replacement, 80 ° C
Keep on. Immediately before dropping the pre-emulsion having the following composition, 0.7 part by weight of ammonium persulfate was added, and the pre-emulsion was dropped over 3 hours. Deionized water 338 parts by weight Diacetone acrylamide 32 parts by weight Acrylic acid 3.2 parts by weight Styrene 97 parts by weight Methyl methacrylate 260 parts by weight 2-Ethylhexyl acrylate 100 parts by weight n-Butyl acrylate 150 parts by weight Newcol 707SF 62 parts by weight Ammonium persulfate 1 .2 parts by weight From 30 minutes after the completion of dropping, a solution of 0.7 parts by weight of ammonium persulfate in 7 parts by weight of deionized water is added dropwise for 30 minutes, and the solution is kept at 80 ° C. for 2 hours, and then about 40 to 40 parts by weight.
After the temperature was lowered to 60 ° C., the pH was adjusted to 8 to 9 with aqueous ammonia to obtain an emulsion A-1 having a solid content of 51.2% by weight and a particle size of 0.16 μm.

Production of Alkoxysilyl Group-Containing Copolymer Aqueous Dispersion Production Example 1 270 parts by weight of deionized water and 1.8 parts by weight of Newcol 707SF were added to a 2-liter four-necked flask, and the temperature was maintained at 80 ° C. after purging with nitrogen. . Immediately before dropping the pre-emulsion having the following composition, 0.6 part by weight of ammonium persulfate was added, and the pre-emulsion was dropped over 2 hours. Deionized water 210 parts by weight Methyl methacrylate 128 parts by weight Ethyl acrylate 96 parts by weight n-Butyl acrylate 78.4 parts by weight 2-Hydroxyethyl methacrylate 16 parts by weight Acrylic acid 1.6 parts by weight Newcol 707SF 31 parts by weight Ammonium persulfate 0.7 By weight From 30 minutes after the completion of dropping, a pre-emulsion having the following composition was further dropped over 1.5 hours. Deionized water 128 parts by weight Styrene 38.4 parts by weight n-Butyl acrylate 76.8 parts by weight γ-methacryloxypropyltrimethoxysilane 76.8 parts by weight Newcol 707SF 18.5 parts by weight Ammonium persulfate 0.3 parts by weight From 30 minutes later, a solution prepared by dissolving 0.6 part by weight of ammonium persulfate in 7 parts by weight of deionized water was added dropwise for 30 minutes, and the temperature was kept at 80 ° C for 2 hours, and then about 40 ° C.
After lowering the temperature to 2, adjust the pH to 8-9 with aqueous ammonia,
An emulsion A-2 having a solid content of 44.7% by weight and a particle size of 0.17 μm was obtained.

Preparation of Resin Mixture In a 1 liter stainless steel container, 513 parts by weight of emulsion A-1, 7.65 parts by weight of adipic dihydrazide, 35% by weight of glass call SW-135 (alkoxysilyl group manufactured by Sanyo Kasei Co., Ltd.) 37.5 parts by weight of the copolymer-containing aqueous dispersion containing the copolymer and the Si content of 1.45% by weight were added and stirred to obtain a resin mixture D-1. Similarly, resin mixture liquids D-2 to D-8 were obtained based on the formulations shown in Table 1.

[0017]

[Table 1]

Example 1 A 1-liter stainless steel container was charged with the pigment paste formulation shown in Table 2 below and stirred with a disper for 30 minutes to prepare a pigment paste. Then, in a letdown step, resin liquid D-1 was used.
558.2 parts by weight, Texanol 38 parts by weight, SN Deformer A-63 7 parts by weight, Primal TT-6
6 parts by weight of 35, 1 part by weight of aqueous ammonia and 20 parts by weight of mineral spirit were added and stirred for 20 minutes to obtain an aqueous paint.

[0019]

[Table 2]

(Note) All compounding amounts are parts by weight. * 1 San Nopco Co., Ltd. pigment dispersant * 2 Asahi Denka Co., Ltd. thickener * 3 San Nopco Co., Ltd. defoamer * 4 Takeda Pharmaceutical Co., Ltd. preservative * 5 Teika Co., Ltd. white pigment * 6 ROHM & House Co., Ltd. Thickener

Examples 2 to 5 and Comparative Examples 1 to 3 Based on the formulations shown in Table 3, water-based paints were obtained in the same manner as in Example 1. Coating E obtained in Examples 1-5 and Comparative Examples 1-3
-1 to E-8 are diluted with tap water to 100 mm x 300 mm
× 3mm slate plate coated with a doctor blade to a wet film thickness of 1mm, the coated plate at 20 ℃, 65 wt% R
It was left under H for 14 days. The following test was done about the obtained test plate. Table 3 shows the results.

[0022]

[Table 3]

(1) Initial Adhesion Property The coating film is scratched at an angle of 60 ° with an NT cutter, a gum tape is attached, and the gum tape is peeled off at a rapid speed. The coated surface was visually evaluated. ⊚: No peeling is observed. ◯: Peeling is observed in a part of the coating film of the scratch on the cutter. Δ: 10 to 25% Peeling of the coating film is recognized. X: 25% or more peeling of the coating film is recognized.

(2) Water resistance test The test plate was half-immersed in running water, and after 7 days, the test plate was pulled up and the coated surface was visually evaluated. ⊚: No change ◯: Partial blistering ×: After full blistering evaluation, after initial drying for 1 day at 20 ° C. and 65% RH, (1) initial adhesion test was conducted again.

(3) Water Permeability Test Using the test plate, a water permeability test of JISA-6910 was conducted.

(4) Strength of adhesion (standard time, after water immersion) According to JISA-6910. Test plate is 70 × 70 × 20
E-1 ~ E directly on m / m mortar board without sealer
-8 was applied in a 1 m / m thick mold.

(5) Hot and cold repeated test: JISA-6
According to 910. Create a test plate in the same manner as the adhesion strength in (4).

(6) Moisture Permeability Test E-1 to E-8 were respectively applied to a release paper with a 1 mm doctor blade, dried at 20 ° C. and 65% RH for 7 days, and then the coating film was peeled off to remove the surface. Turn it over on the back,
After drying again for 7 days, a moisture permeability test was conducted by the cup method of JISZ-0208-76.

(7) Zero-span test A groove having a depth of 2.5 mm and a width of 3 mm is provided on the lower surface of a 70 × 150 × 5 mm flexible plate, and 1 mm is provided on the opposite side of the groove.
Each of E-1 to E-8 was applied with a doctor blade of No. 1 and dried at 20 ° C. and 65% RH for 14 days, and then the flexible plate was cut into two in the middle of the groove for use in the test. The tensile speed of the tester is 5 mm / min, and the elongation when cracks occur on the coated surface is taken as the zero span value (mm).

(8) Weather resistance test The test plate was mounted on a 35 ° outdoor bakuro test stand on the south side, and 3
The surface was washed with water after being subjected to a yearly background, and the coated surface was visually evaluated. ⊚: No change ○: Slight stain and no decrease in gloss Δ: Stain or decrease in gloss is recognized. X: Staining or deterioration in gloss is remarkable.

[0031]

As can be seen from Table 3, the water-based coating composition for normal drying of the present invention has a secondary adhesion after the water resistance test as compared with the water-based coating compositions (Comparative Examples 1 to 3) which do not satisfy the requirements of the present invention. Good, well-balanced and excellent in water resistance, water permeability, adhesion strength, hot and cold repeatability, moisture permeability, zero span and outdoor weather resistance. In the comparative example, the composition of the aqueous carbonyl group-containing copolymer and the dihydrazide compound (Comparative Example 1) and the composition of the aqueous carbonyl group-containing copolymer solution and the aqueous dispersion of the alkoxysilyl group-containing copolymer (Comparative Example 2) The two-component system of
It can be seen that the effects of the present invention are excellent because the secondary adhesion after water resistance is poor.

Claims (4)

[Claims] 1. A dihydrazide compound (B) represented by the following formula as a crosslinking agent is added to an aqueous dispersion of a carbonyl group-containing copolymer (A) in an amount of 0.0 to 1 mol of a carbonyl group.
1 to 2 mol was added, and the alkoxysilyl group-containing copolymer aqueous dispersion (C) was further added in an amount of 0.5 to 5 with respect to 100 parts by weight of the solid content of the carbonyl group-containing copolymer aqueous dispersion (A).
Aqueous paint for normal temperature drying, which is blended with 0 parts by weight (solid content). _{H 2 N-NH-CO- (} C n H 2n) -CO-NH-N
H ₂ (n ≦ 8) 2. The carbonyl group-containing copolymer aqueous dispersion (A) contains (a) a polymerizable carbonyl group-containing monomer having at least one carbonyl group in one molecule of 0.1.
To 30% by weight, (b) monoolefinic unsaturated carboxylic acid having 3 to 5 carbon atoms, unsaturated carboxylic acid amide, N-alkyl and / or N-alkylol derivative of the unsaturated carboxylic acid amide , 0 to 1 monomer selected from the group consisting of mono-olefinically unsaturated carboxylic acids
0% by weight, and (c) vinyl aromatic compound, n-alkyl ester of acrylic acid having 1 to 8 carbon atoms, n-alkyl ester of methacrylic acid having 1 to 8 carbon atoms, vinyl ester of saturated carboxylic acid, Disperse a monomer mixture containing 60 to 99.9% by weight of a monomer selected from the group consisting of 1,3-dienes, tert-butyl acrylate, vinyl halides, ethylene, acrylonitrile, and methacrylonitrile. The room-temperature drying aqueous paint according to claim 1, which is a copolymer dispersion obtained by emulsion polymerization in the presence of an agent. 3. The aqueous coating composition for normal temperature drying according to claim 1, wherein the monomer (a) is diacetone acrylamide and / or diacetone methacrylamide. 4. An alkoxysilyl group-containing copolymer aqueous dispersion (c) was obtained by solution polymerization of an alkoxysilyl group vinyl monomer with another monomer containing an acid group-containing unsaturated monomer. The copolymer dispersion liquid formed by neutralizing a copolymer having an acid group with an amine compound and dispersing the copolymer in water.
An aqueous paint for normal temperature drying according to any one of 1 to 3.