JP3294576B2 - Water-dispersed coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-dispersed coating composition which forms a coating film having excellent storage stability and excellent water resistance, warm water resistance, solvent resistance and the like.

[0002]

2. Description of the Related Art In recent years, environmental regulations have become stricter, and from the viewpoint of resource saving, the paint industry has shifted from a paint using an organic solvent as a solvent to a paint using water or a solventless paint. Is being made. A typical example of a paint using water is an aqueous emulsion paint.
In fact, the paint has to be said to be inferior in water resistance, warm water resistance, solvent resistance and the like as compared with the organic solvent type paint. As a means for solving this problem, a method has been considered in which an epoxy resin which is considered to have good water resistance is used in combination with an aqueous resin (for example, Japanese Patent Application Laid-Open No. 52-197).
Nos. 29, 57-96073 and 57-13
9160, JP-A-1-207374, and 3
No. 1000082, No. 4-318091, No. 11-124539, etc.).

[0003] In each of the methods disclosed in these publications, a curing agent for an epoxy resin is used, and a two-pack type is mainly used. However, the two-pack type requires that the main agent and the curing agent be mixed immediately before coating, and that the reaction between the two progresses, that is, it is necessary to apply before the pot life, so that the coating workability is poor. There was a problem. On the other hand, a one-pack type in which both are mixed in advance has been developed, but because of the high reactivity of both, the viscosity tends to increase during storage, and it has not yet been widely used.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and has excellent storage stability. Further, even if a curing agent is not used, water resistance and warm water resistance can be attained. It is an object of the present invention to provide a water-dispersed coating composition which forms a coating film having excellent solvent resistance and the like.

[0005]

Means for Solving the Problems The present invention has been intensively studied in order to achieve the above-mentioned object, and as a result, it has been found that the above-mentioned object can be achieved by the following constitution, and the present invention has been achieved. That is, the present invention contains the following component (A) and component (B), and the mass solid content ratio of the component (A) and the component (B) is (100: 1 to 20). It relates to a water-dispersed coating composition characterized by the above. (A) Acrylic resin-based aqueous dispersion obtained by emulsion polymerization of an ethylenically unsaturated monomer containing 0.1 to 10 mol% of an ethylenically unsaturated monomer having a glycidyl group or an alkoxysilyl group in water. And (B) an epoxy resin-based aqueous dispersion.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The acrylic resin-based aqueous dispersion (component (A)) used in the present invention is obtained by dispersing an acrylic resin in water as an emulsion polymer. This acrylic resin-based aqueous dispersion (component (A)) is prepared by mixing a specific ethylenically unsaturated monomer described below in water with an emulsifier, a polymerization initiator, and, if necessary, a chain transfer agent and an emulsion stabilizer. Etc., usually 60
It is an aqueous dispersion obtained by emulsion polymerization at a temperature of ９０90 ° C. for 2 to 10 hours. The ethylenically unsaturated monomer is composed of an ethylenically unsaturated monomer having a glycidyl group or an alkoxysilyl group, and an ethylenically unsaturated monomer copolymerizable with the monomer.

Examples of the ethylenically unsaturated monomer having a glycidyl group include glycidyl (meth) acrylate and glycidyl vinyl ether. Examples of the ethylenically unsaturated monomer having an alkoxysilyl group include, for example, vinyl tris (β-methoxyethoxy)
Silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, β- (meth) acryloxyethyltrimethoxysilane, β -(Meth) acryloxyethyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane, γ- (meth) acryloxypropylmethyldipropoxysilane, γ -(Meth) acryloxybutylphenyldimethoxysilane, γ- (meth) acryloxypropyldimethylmethoxysilane, γ
-(Meth) acryloxypropyldiethylmethoxysilane and the like.

Examples of the comonomer copolymerized with the ethylenically unsaturated monomer having a glycidyl group or an alkoxysilyl group include methyl (meth) acrylate and (meth)
Such as ethyl acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, stearyl (meth) acrylate, and cyclohexyl (meth) acrylate; (Meth) acrylic acid esters; (meth) acrylic acid, carboxyl group-containing monomers such as crotonic acid, itaconic acid, itaconic acid half ester, maleic acid, maleic acid half ester, fumaric acid; hydroxy (meth) acrylate Hydroxyl-containing monomers such as ethyl, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and mono (meth) acrylate of polyhydric alcohol; styrenes such as styrene, methylstyrene, and methoxystyrene Monomer: other, vinyl toluene, N-methylol Acrylamide, vinyl acetate, vinyl chloride, (meth) acrylonitrile as a representative.

Examples of the emulsifier which can be used for producing the acrylic resin-based aqueous dispersion (component (A)) include, for example, sulfates of higher alcohols, polyoxyethylene alkyl sulfates, alkylbenzene sulfones, and polyoxypropylene alkyl sulfates. Anionic surfactants such as salts, polyoxyethylene alkylphenol ether sulfate salts, polyoxypropylene alkylphenol ether sulfate salts; polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxypropylene alkylphenol ether, ethylene Nonionic surfactants such as oxide propylene oxide block polymers and sorbitan derivatives;
And so-called reactive emulsifiers such as acrylates of trimethylolpropane and monoallyl alkenylsuccinate.

The polymerization initiator that can be used in the above-mentioned production is not particularly limited as long as it is generally used for emulsion polymerization, and various polymerization initiators can be appropriately used. Among them, water-soluble ones are preferred. Specifically, for example, persulfates such as potassium persulfate and ammonium persulfate; peroxides such as hydrogen peroxide and t-butyl hydroperoxide; and 2,2′-azobis (2-
Amidinopropane) hydrochloride, 4,4'-azobis-4-
Examples include azo compounds such as cyanovaleric acid and 2,2′-azobis (2-methylamidoxime) hydrochloride. A redox type in which a reducing agent such as L-ascorbic acid or sodium thiosulfate is combined with ferrous sulfate or the like can also be used.

Examples of the chain transfer agent which can be used in the above production include long-chain alkyl mercaptans such as n-dodecyl mercaptan, aromatic mercaptans, halogenated hydrocarbons and the like. Examples of the emulsion stabilizer that can be used in the above production include polyvinyl alcohol, hydroxyethyl cellulose, polyvinyl pyrrolidone, and the like. Emulsion polymerization that can be used in the above production can be performed according to a conventional formulation, for example, a monomer batch charging method, a monomer dropping method in which a monomer is continuously dropped, a monomer and water and Mix and emulsify the emulsifier beforehand,
Examples thereof include a pre-emulsion method in which this is dropped, and a method in which these are combined.

The acrylic resin-based aqueous dispersion (component (A)) thus obtained is prepared from ammonia, trimethylamine, triethylamine, dimethylethanolamine in order to improve freeze-thaw stability and storage stability. Those adjusted to pH 6 to 9 with amines such as are preferred. Acrylic resin-based aqueous dispersion used in the present invention (component (A))
Acrylic resin contained in the, i.e., the emulsion polymer is an ethylenically unsaturated monomer having a glycidyl group or an alkoxysilyl group, in order to improve the water resistance of the resulting coating film, warm water resistance, and solvent resistance. 0.1 to 10 mol%, preferably 1 to 5 mol%.

If the content of the ethylenically unsaturated monomer having a glycidyl group or an alkoxysilyl group is less than the above range, water resistance, warm water resistance, solvent resistance, etc. are deteriorated, and conversely, it is too large. In addition, storage stability is deteriorated, and an ethylenically unsaturated monomer having an alkoxysilyl group is not preferable because the coating film becomes brittle. Further, the emulsion polymer composed of the acrylic resin contained in the component (A),
0.1% of the ethylenically unsaturated monomer having a carboxyl group.
It is desirable to contain 5 to 10 mol%, preferably 1 to 5 mol%. By containing the monomer, the storage stability is improved, and the physical strength of the coating film obtained by the crosslinking reaction with the glycidyl group is improved. In addition,
If the content is too large, the water resistance decreases, which is not preferable.

The epoxy resin aqueous dispersion (component (B)) used in the present invention is an epoxy resin aqueous dispersion.
As the epoxy resin-based aqueous dispersion (component (B)),
Glycidyl ether type epoxy resin obtained by condensing epichlorohydrin with bisphenols or dialcohols, or glycidyl ester type epoxy resin obtained by condensing epichlorohydrin with carboxylic acids A glycidylamine type epoxy resin obtained by a condensation reaction of epichlorohydrin and mainly amines,
An epoxy resin having two or more epoxy groups in one molecule, such as a novolak type epoxy resin obtained by reacting epichlorohydrin and a novolak resin, is treated in water with
Examples thereof include those emulsified in the presence of an emulsifier as described above, and an aqueous dispersion obtained by emulsifying a self-emulsifying epoxy resin in water.

Particularly, the epoxy resin contained in the epoxy resin-based aqueous dispersion (component (B)) of the present invention is a liquid at room temperature, and more preferably an epoxy equivalent of 100 to 100.
An epoxy resin of 300 g / eq is preferred because of good storage stability. The water-dispersed coating composition of the present invention comprises an acrylic resin-based water dispersion (component (A)) and an epoxy resin-based water dispersion (component (B)) as a vehicle component, and the mass solid content ratio of both components is as follows. , (100: 1 to 20), preferably (1
00: 3 to 18). Component (B)
However, if the amount is less than the above range, no improvement in water resistance of the obtained coating film is particularly observed. On the other hand, if the amount is too large, storage stability tends to deteriorate, which is not preferable. The water-dispersed coating composition of the present invention comprises the above-described components (A) and (B) as essential components, and further, if necessary, a fungicide, a preservative,
When blending an ultraviolet absorber, a light stability, a film-forming aid, an antifreezing agent, and further an extender or a coloring pigment, it is composed of a blending of various additives such as a dispersant and an anti-settling agent. The water-dispersed coating composition of the present invention can be applied to various inorganic materials, metal materials, wood materials, plastic materials, etc., and forms an excellent cured coating film by natural drying or forced drying at a temperature of 100 ° C. or less. It is possible to

[0016]

The present invention will be described in more detail with reference to the following examples. In the examples, "parts" and "%" are shown on a mass basis unless otherwise specified. <Preparation of Acrylic Resin Aqueous Dispersion A-1> In a separable flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer, 167.5 parts of ion-exchanged water, ammonium polyoxyethylene alkylphenyl ether sulfate [first After adding 2.5 parts of “Hitenol NO8” manufactured by Kogyo Seiyaku Co., Ltd., the temperature was raised to 78 ° C. After completion of the temperature rise, 1.3 parts of potassium sulfate was added as a polymerization initiator, and after 5 minutes, a previously prepared ethylenically unsaturated monomer mixture (A shown in Table 1)
509 parts, “HYTENOL NO8” 10
Of a pre-emulsion emulsion consisting of 246 parts of ion-exchanged water was dropped over 3 hours. After completion of the dropping, the mixture was aged for 1 hour, 20 parts of a 1% aqueous potassium persulfate solution was added dropwise over 30 minutes, and then aged for 90 minutes. 40
After cooling to ° C., 2.5 parts of 25% aqueous ammonia and ion-exchanged water were added, and the mixture was adjusted to have a nonvolatile content of 50% and a pH of 8.5 to prepare an acrylic resin-based aqueous dispersion A-1.

As the monomers, A-2 to A-2 shown in Table 1 are used.
Except for using the monomer mixture of A-5, in the same manner as the acrylic resin-based aqueous dispersion A-1, a nonvolatile content concentration of 50%,
Acrylic resin-based aqueous dispersions A-2 and A-3 having a pH of 8.5,
A-4 and A-5 were prepared. The abbreviations of the monomers shown in Table 1 have the following meanings. MMA: methyl methacrylate St: styrene 2EHA: 2-ethylhexyl acrylate MAA: methacrylic acid GMA: glycidyl methacrylate MPTMS: γ-methacryloxypropyl trimethoxysilane

<Preparation of Epoxy Resin Aqueous Dispersion B> A novolak type epoxy resin [“Epicoat 154” manufactured by Yuka Shell Epoxy) (liquid at normal temperature; epoxy equivalent)
(176 to 181 g / eq) 60 parts and 3.0 parts of a nonionic surfactant [Deugen ET170 manufactured by Daiichi Kogyo Seiyaku] were added and heated to 70 ° C. Thereafter, 40 parts of ion-exchanged water was added dropwise over 1 hour while stirring with a homomixer, and further cooled to 40 ° C. to prepare an epoxy resin-based aqueous dispersion B having a nonvolatile content of 60%.

Example 1 Acrylic resin-based water dispersion A-1 (concentration of nonvolatile matter: 50)
%) To 100 parts of an epoxy resin-based aqueous dispersion (B)
(Non-volatile content: 60%), and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate [Chisso Corporation's CS
-12 "], 1 part of ethylene glycol monobutyl ether and 3 parts of ethylene glycol were added with stirring, and then diluted with ion-exchanged water to prepare a coating material having a nonvolatile content of 20%.

Examples 2 to 4 and Comparative Examples 1 to 4 In the same manner as in Example 1, the compositions shown in Table 2 were prepared and diluted with ion-exchanged water to prepare a paint having a nonvolatile content of 20%. The coatings obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were tested for adhesion, water resistance, hot water resistance, solvent resistance, and storage stability by the following methods. 2 below. Adhesion test method A film thickness of about 100 when dried on a 7 cm x 15 cm tin plate
It was applied to a thickness of μm and dried at 50 ° C. for 6 hours to prepare a test piece. This test piece was tested by the crosscut tape method and evaluated according to the following criteria. ◎: There is no peeling of the coating film at all. ：: The area of the defective part is less than 20% of the whole. Δ: The area of the defective part is 20 to 60% of the whole. ×: The area of the defective part exceeds 60% of the whole.

Water resistance test method A 7 cm x 15 cm tin plate having a dry film thickness of about 100
It was applied to a thickness of μm and dried at 50 ° C. for 6 hours to prepare a test piece. Further, after the test piece was immersed in water at 20 ° C. for 15 days, the test piece was taken out of the water and evaluated by the following criteria based on the appearance and touch of the blister. The size standard was based on the Japan Paint Manufacturers Association standard. ：: swelling is smaller than 8S ：: swelling is 7S to 6M △: swelling is 5M to 4L ×: swelling is larger than 3L

Test method for warm water resistance A 7 cm x 15 cm tin plate having a dry film thickness of about 100
It was applied to a thickness of μm and dried at 50 ° C. for 6 hours to prepare a test piece. Furthermore, the test piece was immersed in water at 50 ° C. for 15 days, taken out of the water, and evaluated based on the following criteria based on the appearance and touch of the blister. The size standard was based on the Japan Paint Manufacturers Association standard. ：: swelling is smaller than 8S ：: swelling is 7S to 6M △: swelling is 5M to 4L ×: swelling is larger than 3L

According to JIS K5400, a test method for solvent resistance was applied to a glass plate so as to have a dry film thickness of about 500 μm, and dried at 50 ° C. for 6 hours to form a film. Peel this coating from the glass plate,
It was cut into 5 cm × 5 cm. After immersing the test piece in toluene for 24 hours, the test piece was taken out and the side expansion coefficient (%) was measured. The smaller the coefficient of side expansion, the higher the solvent resistance. Test Method of Storage Stability The viscosity change of the liquid when stored at 50 ° C. in a sealed container was measured and evaluated according to the following criteria. ◎: Does not thicken even after 4 weeks or more ：: Thickens about 2 times in 3 weeks or more to less than 4 weeks △: Thickens about 2 times in 3 weeks or more to less than 3 weeks ×: Less than 1 week Gel

As can be seen from Table 2, the water-dispersible paints of the present invention have excellent storage stability as well as adhesion.
Water resistance, warm water resistance and solvent resistance were excellent. On the other hand, Comparative Examples 1 and 2, which did not contain the epoxy resin-based aqueous dispersion, were inferior in adhesion, warm water resistance, and solvent resistance. Comparative Example 3 using an acrylic resin containing no glycidyl group or alkoxysilyl group was inferior in adhesion, hot water resistance and solvent resistance. Comparative Example 4 in which the amount of the epoxy resin-based aqueous dispersion was excessive was inferior in storage stability.

[0025]

Table 1 Table 1 Monomer composition of component A (unit: mol%)

[0026]

[Table 2] Table 2

[0027]

The water-dispersed coating composition of the present invention forms a coating film which is excellent in storage stability, water resistance, hot water resistance, solvent resistance and the like.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuyoshi Tsuneda 1-981 Shimonaga, Nishinasuno-machi, Nasu-gun, Tochigi Prefecture (56) References JP-A-57-96073 (JP, A) JP-A-3-21610 (JP, A) JP-A-6-157982 (JP, A) JP-A-6-287478 (JP, A) JP-A-7-316495 (JP, A) JP-A-2001-131465 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C09D 1/00-201/10

Claims (3)

(57) [Claims] 1. The composition contains the following component (A) and component (B), and the component (A) and the component (B) have a mass solid content ratio of (100: 1 to 20). A water-dispersed coating composition comprising: (A) Acrylic resin-based aqueous dispersion obtained by emulsion polymerization of an ethylenically unsaturated monomer containing 0.1 to 10 mol% of an ethylenically unsaturated monomer having a glycidyl group or an alkoxysilyl group in water. And (B) an epoxy resin-based aqueous dispersion. 2. The water-dispersed coating composition according to claim 1, wherein the acrylic resin contained in the component (A) contains 0.5 to 10 mol% of an ethylenically unsaturated monomer having a carboxyl group. . 3. The epoxy resin contained in the component (B),
The water-dispersed coating composition according to claim 1, which is liquid at ordinary temperature.