JP3414424B2 - Water-dispersed resin composition and paint using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-dispersible resin composition useful for paints, adhesives and the like, and paints using the same.

[0002]

2. Description of the Related Art In recent years, labor-saving and energy-saving demands have been high for coatings and adhesives for coating automobiles, steel furniture, electric appliances and the like. Furthermore, in order to prevent air pollution due to the organic solvent emitted from the paint, the transition from the conventional organic solvent type paint to the water-based paint is progressing. However, it has not been found that a water-based paint that can be baked for a short time and has a good balance of processability, water resistance, adhesiveness, flexibility, etc. of a cured coating film.

An epoxy resin / acrylic resin reaction product using an epoxy resin obtained by reacting bisphenol A with a low molecular weight epoxy disclosed in JP-A-3-114456 is still insufficient in processability and adhesion. I was not satisfied.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to solve such problems, and enables baking for a short time, and the cured coating film has a water-dispersible resin composition excellent in workability and adhesion. It is to provide things.

[0005]

[Means for Solving the Problems] That is, the present invention provides a method for polymerizing a copolymerizable unsaturated monomer mixture comprising an ethylenically unsaturated aliphatic carboxylic acid and other copolymerizable unsaturated monomers. Acrylic resin (A) obtained by partially neutralizing a polymer having a carboxyl group having an average molecular weight of 5,000 to 12,000 and an acid value of 230 to 350 with ammonia or amine.
And a bisphenol A type epoxy resin are chain-extended under a primary amine to obtain a molecular weight dispersity (weight average molecular weight / number average molecular weight) of 2.0 to 8.0, and a number average molecular weight of 4, The aromatic epoxy resin (B) having a weight ratio of (A) / (B) of 500 to 9,000 is 5/95 to.
The present invention relates to a water-dispersible resin composition obtained by water-dispersing an epoxy / acrylic resin reaction product reacted as 40/60, and a paint using the same.

The present invention will be described in detail below. (A) of the present invention
The component acrylic resin is a copolymerizable unsaturated monomer mixture consisting of an ethylenically unsaturated aliphatic carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, itaconic acid and other copolymerizable unsaturated monomers. Number average molecular weight 5,000 to 12,000 obtained by polymerization and acid value 230 to 350
Is a polymer having a carboxyl group (hereinafter sometimes referred to as an acrylic resin before neutralization) partially neutralized with ammonia or amine.

Other copolymerizable unsaturated monomers mentioned above include 2-hydroxyethyl acrylate and 2-acrylic acid acrylate.
Α, β-ethylenically unsaturated monomers having a hydroxyl group such as hydroxypropyl, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, acrylic acid Alkyl ester of α, β-monoethylenically unsaturated carboxylic acid such as 2-ethylhexyl, methyl methacrylate, n-butyl methacrylate, acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide, etc. Acrylamide derivatives, glycidyl esters of α, β-monoethylenically unsaturated carboxylic acids such as glycidyl acrylate and glycidyl methacrylate, vinyl acetates such as vinyl acetate and vinyl propionate, styrene, α-methylstyrene And the like aromatic unsaturated monomers such as vinyl toluene.

The above polymerization can be carried out by a conventional method in the presence of a radical catalyst such as azobisisobutyronitrile, t-butylperoxybenzoate, benzoyl peroxide, dibutyl peroxide, cumene hydroperoxide and the like. .

The acrylic resin before neutralization has an acid value of 230 to 35.
It is adjusted to 0, preferably 250 to 300. Acid value is 2
If it is less than 30, the water solubility or water dispersibility of the epoxy-acrylic resin reaction product is poor and the stability of the coating composition is poor. On the other hand, when the acid value exceeds 350, the coating film properties (particularly the hot water resistance) are deteriorated, and when the components (A) and (B) are reacted, gelation is likely to occur.

The number average molecular weight (G
PC method, standard polystyrene conversion value) is 5,000 to 1
It is adjusted to 2,000, preferably 7,000 to 10,000. If the number average molecular weight is less than 5,000, the hot water resistance and processability are poor, and if it exceeds 12,000, the viscosity of the final product, the water-dispersible resin composition, becomes high.

The acrylic resin before neutralization is partially neutralized with ammonia or amine, and then water-soluble or water-dispersed to obtain a partially neutralized acrylic resin (A). Suitable amines here include, for example, monopropylamine, monobutylamine, diethylamine, dibutylamine, triethylamine, tributylamine, monoethanolamine, ethylmonoethanolamine, monocyclohexylamine, dimethylaminoethanol, 2-amino-2-. Methyl-1
-Primary grades such as propanol, morpholine, piperidine,
Secondary and tertiary aliphatic or cycloaliphatic amines can be used. Ammonia and amine are preferably used in an amount of 0.6 or more and less than 1.0 mol per 1 equivalent of the acid group. If the amine is less than 0.6 mol, the water dispersibility or water solubility tends to be poor, and if it is 1.0 mol or more, the viscosity of the final product tends to be high.

The aromatic epoxy resin (B) used in the present invention has a molecular weight dispersity (weight average molecular weight / number average molecular weight) of 2 obtained by polymerizing a bisphenol A type epoxy resin under an amine solvent. The number average molecular weight is in the range of 4,500 to 9,000.

Examples of the bisphenol A type epoxy resin include Epicoat 828 and 10 manufactured by Shell Chemical Co.
01, 1004, 1007, 1009, Epon 829,
Dow DER 668, 667, 66 from Dow Chemical
9, R304, R301, R3 manufactured by Mitsui Petrochemical Industry Co., Ltd.
07, R309 and the like.

Examples of amine catalysts include monopropylamine, monobutylamine, diethylamine, dibutylamine, triethylamine, tributylamine, monoethanolamine, ethylmonoethanolamine, monocyclohexylamine, dimethylaminoethanol, 2
Primary, secondary and tertiary aliphatic or cycloaliphatic amines such as -amino-2-methyl-1-propanol, morpholine, piperidine and the like can be used.

The conditions for chain extension of the bisphenol A type epoxy resin under the amine catalyst are not particularly limited, but the following conditions are usually adopted. That is, 0.1 to 5 parts by weight of an amine catalyst and 100 to 20 parts by weight of a bisphenol A type epoxy resin, a solvent (n-butanol, methyl isobutyl ketone, etc.) used as necessary 20 to
100 to 100 parts by weight, 1 to 10 at 90 to 130 ° C
Perform time chain extension.

When the molecular weight dispersity in the aromatic epoxy resin (B) is less than 2.0, the flexibility of the cured coating film decreases,
On the other hand, when it exceeds 8.0, the processability and adhesion of the cured coating film are deteriorated, and the viscosity of the coating composition is increased, so that the stability of the coating composition is degraded. From the viewpoint of these characteristics, 2.8 to 3.1 is preferable.

If the number average molecular weight in the aromatic epoxy resin (B) is less than 4,500, the processability and adhesion of the cured coating film will decrease, while if it exceeds 9,000, the acrylic resin (A) will be At the time of reaction, gelation is likely to occur, the viscosity of the coating material increases, and the stability of the coating material decreases. From the viewpoint of these characteristics, the number average molecular weight is preferably 5,500 to 7,500, more preferably 6,000 to 7,000.

The number of epoxy groups in the aromatic epoxy resin (B) is preferably 1.0 to 1.7 on average in one molecule of the aromatic epoxy resin (B). When the average number is less than 1.0 in one molecule, the viscosity tends to increase during the reaction with the acrylic resin (A), and the stability during water dispersion and the coating viscosity tend to decrease. On the other hand, 1.7 If the number exceeds the limit, the flexibility, processability, adhesion, etc. of the cured coating film will tend to deteriorate.

In the present invention, the reaction between the acrylic resin (A) and the aromatic epoxy resin (B) is carried out by adding the partially neutralized acrylic resin (A) to the aromatic epoxy resin (B) kept at 80 to 100 ° C. Then, the reaction may be performed at 65 to 85 ° C. for 30 minutes to 2 hours. The degree of progress of the reaction can be known by changing the acid value, measuring the oxirane group concentration (%), and the like.

The weight (%) ratio of acrylic resin (A) / aromatic epoxy resin (B) is in the range of 5/95 to 40/60, preferably 10/90 to 40/60. (A)
If the amount of the component used is too large, the processability and corrosion resistance of the coating film will be reduced, and if the amount of component (B) is too large, the water dispersibility and the stability of the coating will be reduced.

The water-dispersible resin composition of the present invention contains hydrochloric acid,
A catalyst such as an inorganic acid such as phosphoric acid or an organic acid such as paratoluenesulfonic acid may be added. The amount used is preferably 1 part by weight or less based on 100 parts by weight of the component (A) (solid content).

The water-dispersible resin composition of the present invention comprises butyl cellosolve, ethyl cellosolve, methyl cellosolve, diacetone alcohol, 3-methoxy-3-methylbutane-.
It can be used by diluting it to a suitable solid content with a mixed solvent of water and a water-soluble solvent such as 1-ol, isopropanol, ethanol, methanol and the like. The mixing ratio of water and the water-soluble organic solvent is 95/5 to 80/20 in weight ratio of water / organic solvent.
Is preferred.

The viscosity when diluted to a solid content of 30% by weight with the above mixed solvent is preferably 50 cps to 2,000 cps. If it is less than 50 cps, the viscosity tends to decrease, and the film thickness of the coating film tends to be thin so that the workability tends to decrease.
If it exceeds 000 cps, the workability during coating tends to be low and the stability of the coating tends to be low.

When the water-dispersible resin composition of the present invention is used as a paint, pigments and other additives may be used depending on the purpose. As the coating method, spray coating, coating with a roll coater, dipping, etc. can be adopted.

[0025]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these. Production Example 1 (Production of acrylic resin) A flask equipped with a stirrer, a reflux condenser, a thermometer and an inert gas inlet was charged with 35 parts by weight of butyl cellosolve and 20 parts by weight of butanol and heated to 130 ° C. 28 parts by weight of styrene and 26 parts of ethyl acrylate
A mixed solution of 50 parts by weight, 46 parts by weight of methacrylic acid and 0.6 part by weight of t-butylperoxybenzoate was applied for 3 hours. Then, 5 parts by weight of butyl cellosolve and 23 parts by weight of butanol were applied for 20 minutes, and then 2
A polymer having a carboxyl group (acid value 30
0, solid content conversion) was obtained.

Thereafter, the mixture was cooled to 100 ° C., 47 parts by weight of water was added, and dimethylaminoethanol 3 was added at 80 ° C.
An acrylic resin was obtained by adding 1 part by weight (neutralization ratio: 65
%). Then, water was added and the heating residue was 43% by weight (1
The temperature was adjusted to 08 ° C. for 3 hours). The acid value of the obtained acrylic resin is 300 (solid content conversion), the number average molecular weight is 9,700, and the weight average molecular weight is 24,200.
Met.

Production Example 2 (Preparation of aromatic epoxy resin) 376 parts by weight of bisphenol A type glycidyl ether type epoxy resin (trade name R307, manufactured by Mitsui Petrochemical) and 125 parts by weight of n-butanol are weighed and stirred. Machine,
A reflux condenser, a thermometer and an inert gas inlet were put into the flask. Dissolve slowly with stirring and then increase the temperature to 1
It was kept at 10 ° C. After dehydration under reflux for 1 hour, 3.0 parts of monoethanolamine was added and reacted at the same temperature for 3 hours to synthesize an aromatic epoxy resin. The number average molecular weight (Mn) of this product is 6,100, the weight average molecular weight (Mw) is 36,
200, the molecular weight dispersity (Mw / Mn) was 5.9, and the number of epoxy groups in one molecule was 1.3.

Production Example 3 (Preparation of aromatic epoxy resin) 376 parts by weight of bisphenol A type glycidyl ether type epoxy resin (trade name R307, manufactured by Mitsui Petrochemical) and 125 parts by weight of n-butanol are weighed and stirred. Machine,
A reflux condenser, a thermometer and an inert gas inlet were put into the flask. Dissolve slowly with stirring and then increase the temperature to 1
It was kept at 10 ° C. After dehydration under reflux for 1 hour, 2.6 parts of monoethanolamine was added and reacted for 3 hours to synthesize an aromatic epoxy resin. At this time, the number average molecular weight (Mn) is 5,010, the weight average molecular weight (Mw) is 22,540, the molecular weight dispersity (Mw / Mn) is 4.5, and the number of epoxy groups in one molecule is 1.5. Met.

Production Example 4 (Preparation of Aromatic Epoxy Resin) 376 parts by weight of bisphenol A type glycidyl ether type epoxy resin (trade name R304, manufactured by Mitsui Petrochemical) and 125 parts by weight of n-butanol are weighed and stirred. Machine,
A reflux condenser, a thermometer and an inert gas inlet were put into the flask. Dissolve slowly with stirring and then increase the temperature to 1
It was kept at 10 ° C. After dehydration under reflux for 1 hour, 3.4 parts of monoethanolamine was added and reacted for 3 hours to synthesize an aromatic epoxy resin. At this time, the number average molecular weight (Mn) was 6,200, the weight average molecular weight (Mw) was 24,600, the molecular weight dispersity (Mw / Mn) was 4.0, and the number of epoxy groups in one molecule was 1.4. Met.

Production Example 5 (Preparation of Aromatic Epoxy Resin) 376 parts by weight of bisphenol A type glycidyl ether type epoxy resin (trade name R304 manufactured by Mitsui Petrochemical Co., Ltd.) and 125 parts by weight of n-butanol are weighed and stirred. A reflux condenser, a thermometer and an inert gas inlet were put in the flask. Dissolve slowly with stirring and then increase the temperature to 11
It was kept at 0 ° C. After reflux dehydration for 1 hour, 4.5 parts of monoethanolamine was added and reacted for 3 hours to synthesize an aromatic epoxy resin. The number average molecular weight (Mn) at this time is 4,
The weight average molecular weight (Mw) was 700, the molecular weight dispersity (Mw / Mn) was 2.7, and the number of epoxy groups in one molecule was 1.6.

Production Example 6 (Production of Aromatic Epoxy Resin) Diglycidyl ether type DE of bisphenol A
405 parts by weight of R343 (manufactured by Dow Chemical Co.) and 220 parts by weight of bisphenol are weighed out and stirred, a stirrer, a reflux condenser,
The flask was charged with a thermometer and an inert gas inlet. Adjust the heating to reach about 130 ℃ in 30 minutes,
After that, the heating was stopped and the reaction heat was used to raise the temperature to 190 ° C. The reaction was carried out at that temperature for 2 hours to synthesize an epoxy resin. The average number of epoxies in one molecule was 1.35. The number average molecular weight (Mn) is 6,550, the weight average molecular weight (Mw) is 19,600, and the molecular weight dispersity (Mw / M).
n) was 2.99.

Example 1 Solfit 66. was added to the epoxy resin solution obtained in Production Example 2.
5 parts by weight and 75.4 parts by weight of butanol were added and well stirred, and when the temperature reached 100 ° C., 255.3 parts by weight of the acrylic resin synthesized in Production Example 1 was added (epoxy resin / acrylic resin = 80 / 20; solid fraction). 1 at 80 ° C
After stirring for an hour, an epoxy-acrylic resin reaction product was obtained. The acid value at this time was 22.2. Thereafter, 1,060 parts by weight of water was added over 1 hour to obtain a white water-dispersible resin. Then, it was subjected to vacuum dewatering, and the solvent composition was adjusted to be water / solfit / 1-butanol = 85/7/8. The resin was further adjusted to a solid content of 30% by weight with water.
At this time, the viscosity is 100 cps (B type viscosity 6 rp.
m).

Example 2 Solfit 66. was added to the epoxy resin solution obtained in Production Example 3.
After adding 5 parts by weight and 75.4 parts by weight of butanol, stirring well, and cooling to 100 ° C., 255.3 parts by weight of the acrylic resin synthesized in Production Example 1 was added (epoxy resin / acrylic resin = 80/20; Solid fraction). 1 at 80 ℃
The stirring was continued for a period of time to obtain an epoxy-acrylic resin reaction product. The acid value at this time was 19.8. Then water 1,
060 parts by weight was added over 1 hour to obtain a white water-dispersible resin. Then, it was dissolved under reduced pressure, and the solvent composition was adjusted to be water / solfit / 1-butanol = 85/7/8. This resin was adjusted with water to a solid content of 30% by weight. The viscosity at this time is 100 cps (B type viscosity 6
r. p. m).

Example 3 Solfit 66. was added to the epoxy resin solution obtained in Production Example 4.
5 parts by weight and 75.4 parts by weight of butanol were added and well stirred, and when the temperature reached 100 ° C., 255.3 parts by weight of the acrylic resin synthesized in Production Example 1 was added (epoxy resin / acrylic resin = 80 / 20; solid fraction). 1 at 80 ° C
After stirring for an hour, an epoxy-acrylic reaction product was obtained. The acid value at this time was 20.6. Thereafter, 1,060 parts by weight of water was added over 1 hour to obtain a white water-dispersible resin. After that, the solution was decompressed under reduced pressure and the solvent composition (water / solfit / 1-
Butanol = 85/7/8). The resin was further adjusted to a solid content of 30% by weight with water. The viscosity at this time is 1,200 cps (B-type viscosity 6 r.p.m.)
Met.

Example 4 Solfit 66. was added to the epoxy resin solution obtained in Production Example 5.
After adding 5 parts by weight and 75.4 parts by weight of butanol, stirring well, and cooling to 100 ° C., 255.3 parts by weight of the acrylic resin synthesized in Production Example 1 was added (epoxy resin / acrylic resin = 80/20; Solid fraction). 1 at 80 ℃
The stirring was continued for a period of time to obtain an epoxy / acrylic reaction product. The acid value at this time was 14.6. Then water 1,0
60 parts by weight was added over 1 hour to obtain a white water-dispersible resin. Then, it was dissolved under reduced pressure and adjusted to a solvent composition (water / solfit / 1-butanol = 85/7/8. This resin was adjusted to 30% by weight in solid content with water. Had a viscosity of 1,040 cps (B-type viscosity of 6 rpm).

Comparative Example 1 The epoxy resin obtained in Production Example 6 was cooled to 130 ° C., butanol (50 parts by weight) was added, and the mixture was stirred well. When the temperature reached 100 ° C., the partially neutralized acrylic resin synthesized in Production Example 1 was used. Resin 4
35 parts by weight was added (epoxy resin / acrylic resin =
80/20; solid fraction). The mixture was stirred at 80 ° C. for 30 minutes to obtain an epoxy / acrylic reaction product. The acid value at this time was 34. Then, 1,100 parts by weight of water was added over 1 hour to obtain a white water-dispersible resin. This resin is a solid component 30
Further adjusted to wt% with water. The viscosity at this time is 450c
It was ps (B type viscosity 6 r.p.m).

Comparative Example 2 Using the acrylic resin of Example 1, R309 as an aromatic epoxy resin (Mitsui Petrochemical, Mn: 4800, M
A water-dispersible resin was obtained by the same method using w: 18700, Mw / Mn = 3.9 (no chain extension). That is, 625 parts by weight of Epon 1009 is heated to 130 ° C.,
Thereafter, 50 parts by weight of butanol was used and further cooled to 10
Add 435 parts by weight of partially neutralized acrylic resin at 0 ° C.,
Incubate at 0 ° C for 30 minutes (acid value 35), then water 1,10
0 part by weight was added to obtain a white water-dispersible resin. Further, the heating residue of this resin was adjusted to 30% by weight with water. Viscosity is 7,800cps (B type viscosity 6r.pm)
Met.

Coating Property Tests The coating properties of the water-based coating compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated under the following conditions. The water-based paint was applied to an aluminum plate (thickness 0.3 mm) with a bar coater # 12. The film thickness was 5 to 7 μm after baking. The coated plate was baked at 270 ° C. for 1 minute and 20 seconds. Then, it was left at room temperature for 24 hours. The coating film characteristic test results are shown in Table 1.

[0039]

[Table 1]

Coating film test method-Pencil hardness: Evaluated according to JIS K5400 using Mitsubishi Uni.・ Boiling resistance; soak in boiling water for 1 hour, then remove
The appearance was judged.・ Adhesion resistance to boiling water; 1 mm on the coating after immersion in boiling water for 1 hour
100 pieces of 1 mm squares were cut and cellophane tape was peeled off, and the peeling rate was determined. Erichsen value after boiling water resistance: After immersion in boiling water for 1 hour, an Erichsen test was used to extrude 5 mm, and the appearance of the coating film was observed. -Stability: The paint was allowed to stand at room temperature (25 ° C) for 60 days, the appearance of the paint was measured, and separation and sedimentation were observed. -Workability: 2T bending (2 kg weight was dropped from a height of 30 cm) was performed. The case where a crack was generated in the bent portion was evaluated as ×, and the case where there was no abnormality was evaluated as ○.

[0041]

The water-dispersible resin composition of the present invention has excellent stability and can be baked for a short time, and the obtained cured coating film is
It has excellent workability and adhesion.

Continuation of front page (56) Reference JP-A-4-342780 (JP, A) JP-A-56-109243 (JP, A) JP-A-60-79072 (JP, A) JP-A-58-40363 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 59/00-59/72 C09D 163/00-163/10

Claims (3)

(57) [Claims] 1. A number average molecular weight of 5,000 to 1 obtained by polymerizing a copolymerizable unsaturated monomer mixture consisting of an ethylenically unsaturated aliphatic carboxylic acid and other copolymerizable unsaturated monomers.
Obtained by chain extending an acrylic resin (A) obtained by partially neutralizing a polymer having a carboxyl group of 2,000 and an acid value of 230 to 350 with ammonia or amine and a bisphenol A type epoxy resin under a primary amine. An aromatic epoxy resin (B) having a molecular weight dispersity (weight average molecular weight / number average molecular weight) of 2.0 to 8.0 and a number average molecular weight of 4,500 to 9,000 (A). A water-dispersible resin composition obtained by water-dispersing an epoxy-acrylic resin reaction product reacted with a weight ratio of / (B) of 5/95 to 40/60. 2. The primary amine is monoethanolamine.
The water-dispersible resin composition according to claim 1. 3. A process according to claim 1 or paint with 2 water-dispersed resin composition.