JPH0713207B2 - Water dispersible resin composition for anticorrosion paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application The present invention relates to a water-dispersible resin used in a vehicle for rust-preventive paint for surface coating of metal for interior and exterior of buildings, chassis of automobiles and the like. It relates to a composition.

(2) Conventional Technology Conventionally, as a vehicle for an anticorrosion paint, a solvent-type paint in which various antirust agents and a colorant are dispersed in a solvent-type resin has been generally used. However, the solvent type has many problems such as occupational safety and health, health and pollution because it has a risk of fire and explosion and toxicity.

A method using cement mortar has been devised to solve these problems, but it is difficult to give a beautiful appearance,
Moreover, due to the increased weight, the use of anticorrosion paints using this is extremely limited.

(3) Problems to be Solved by the Invention Under such circumstances, there are great expectations for water-based rust preventive paints, and various aqueous solution resins and synthetic resin emulsions for this purpose have been introduced. However, paints using aqueous solution resins as a vehicle are sagging. On the other hand, it has a drawback that it is liable to cause stains and has poor water resistance. On the other hand, a paint using a synthetic resin emulsion as a vehicle has poor gloss and thus is inferior in appearance, and is also satisfactory in terms of adhesion to metal materials and rust prevention. It wasn't.

(4) Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of such circumstances, and as a result, have found that the particle size is extremely small and the emulsifier is strongly bonded to the emulsion particles by covalent bonding such as grafting. The inventors have found that a (meth) acrylic acid alkyl ester copolymer water-acid resin emulsion is effective for solving the above-mentioned problems, and completed the present invention.

That is, the present invention includes a (meth) acrylic acid alkyl ester-based monomer selected from a (meth) acrylic acid alkyl ester or a mixed monomer thereof with styrene, which contains an unsaturated carboxylic acid in an amount of 0.1 to 10% by weight, in the presence of a reactive emulsifier. It is composed of a water-dispersible resin composition of a (meth) acrylic acid alkyl ester-based copolymer obtained by emulsion polymerization below, and the glass transition temperature of the copolymer is the copolymer component excluding the reactive emulsifier component. A water-dispersible resin composition for rust-preventive paints, characterized in that it has a temperature of 20 ° C. or higher as calculated by the weight fraction method, and the water-dispersible resin has an average particle diameter of 200 nm or less.

Hereinafter, the present invention will be described in more detail.

The (meth) acrylic acid alkyl ester-based monomer used in the present invention is selected from (meth) acrylic acid alkyl ester or a mixed monomer thereof with styrene. Among them, as the (meth) acrylic acid alkyl ester, a C _{1 to} C ₁₂ alkyl ester of acrylic acid or methacrylic acid, for example, methyl acrylate, ethyl acrylate,
Butyl acrylate, isobutyl acrylate, acrylic acid
2-ethylhexyl, decyl acrylate, dodecyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, lauryl methacrylate, methacrylic acid
2-ethylhexyl and the like, and one or more of these can be used.

Examples of unsaturated carboxylic acids include mono- or di- or higher-valent carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, and itaconic acid.

The amount of the unsaturated carboxylic acid used is 0.1% by weight or more and 10% by weight or less, preferably 1.0% by weight or more and 8% by weight or less, based on 100 parts by weight of the monomer.

If the amount of unsaturated carboxylic acid is less than 0.1% by weight, the adhesion to metal materials will decrease, and conversely the amount of unsaturated carboxylic acid will be 10%.
If it is more than 10% by weight, the water resistance tends to be remarkably reduced.

The glass transition temperature (Tg) of the present invention can be determined from the glass transition temperature of each component constituting the copolymer excluding the reactive emulsifier component according to the following equation.

Tg: Glass transition temperature of copolymer WA: Weight fraction of A component WB: Weight fraction of B component TgA: Glass transition temperature of A component TgB: Glass transition temperature of B component Alkyl (meth) acrylate of the present invention The ester copolymer needs to have a glass transition temperature of 20 ° C. or higher, which is determined by this formula. When the temperature is 20 ° C. or lower, the rust preventive power is inferior, and the glass transition temperature of 20 ° C. or higher, preferably 30 ° C. or higher is suitable for developing the rust preventive power. Further, when the glass transition temperature is high, a uniform film may not be formed by room temperature drying, but addition of a film-forming aid well known in the art, high-temperature drying, or combination of these means, etc. A uniform film can be formed on the surface, and various performances including rust prevention performance can be sufficiently exhibited.

Next, the reactive emulsifier used in the present invention can form particles having an average particle size of 200 nm or less by emulsion polymerization, and has a polymerizable reactive group such as vinyl group, allyl group and methacryl group in its chemical structure. Any emulsifier may be used, but particularly preferred reactive emulsifiers include those having the following general formula.

(1) General formula (However, R ₁ is a hydrocarbon group which may have a substituent,
R ₂ represents hydrogen or a methyl group, and M represents Na or NH ₄ . ) (2) General formula 2 (However, R ₁ represents a hydrocarbon group which may have a substituent, R ₂ represents hydrogen or a methyl group, and M represents Na or NH _4. ) (3) General formula 3 (However, R ₁ represents a hydrocarbon group which may have a substituent, R ₂ represents hydrogen or a methyl group, A is an alkylene group having 2 to 4 carbon atoms, and m is a number of 0 to 100. And X is hydrogen, or a nonionic or anionic hydrophilic group.) (4) General formula 4 (However, R ₁ is an alkyl group, an alkenyl group, or an aralkyl group having 4 to 18 carbon atoms, and R ₂ is hydrogen or 4 to 4 carbon atoms.
18 alkyl group, alkenyl group, or aralkyl group, A is an alkylene group having 2 to 4 carbon atoms, or a substituted alkylene group, n is an integer of 2 to 200, M is an alkali metal atom, NH ₄ , alkanolamine residue It is a base. It is preferable that the reactive emulsifier having the above structural formula is an anion because the object of the present invention is to obtain a water-dispersible resin having an average particle size of 200 nm or less.

Known anionic, nonionic and cationic emulsifiers may be used in combination as necessary, but care should be taken so that the average particle diameter of the water-dispersible resin produced is 200 nm or less.

When the average particle size of the water-dispersible resin is larger than 200 nm, the rust-preventive paint using the water-dispersible resin composition as a vehicle is inferior in smoothness, gloss, etc., and fine irregularities on the substrate surface. Therefore, the object of the present invention cannot be achieved because the adhesiveness may be poor and the adhesion may be poor.

As the polymerization initiator, persulfates such as potassium persulfate and ammonium persulfate, peroxides such as hydrogen peroxide benzoyl peroxide, cumene hydroperoxide and tert-butyl hydroperoxide, and azobisisobutyronitrile are generally used. However, water-soluble initiators and water-soluble redox type initiator systems are particularly preferable.

In obtaining the water-dispersible resin composition of the present invention, the above-mentioned monomers can be used as they are by a conventionally known emulsion polymerization method in the presence of a pre-reactive emulsifier and an initiator. For example, the monomers are polymerized in the presence of an initiator corresponding to 0.1 to 1.0% by weight of the monomers and a reactive emulsifier corresponding to 0.3 to 3.0% by weight, and the solid content concentration is usually
40 to 60% by weight of water-dispersible resin composition is obtained.

The water-dispersible resin composition of the present invention has a glass transition temperature of 20 ° C. or higher as described above, and an unsaturated carboxylic acid in the solid content of 0.1 to 1
It is a water-dispersible resin composition containing 0% by weight and having an average particle size of 200 nm or less obtained by emulsion polymerization in the presence of a reactive emulsifier, but if necessary, it is commonly used in this kind of water-dispersible resin composition. Known film forming aids, dispersants, preservatives, antifoaming agents, anticorrosives and other auxiliary additives can be added.

(5) Examples Next, the present invention will be described in detail with reference to Examples.

Paint formulation Water-dispersible resin composition (concentration 40%) 70.0 parts by weight Water 6.0 Ammonia water 1.3 Texanol (Note 1) 2.3 Butyl cellosolve 3.5 Methanol 2.3 Adecanate UH-420 (Note 2) 0.15 Bissurf 1400 (Note 3) 0.15 Water 6.0 SA Black SBB-167 (Note 4) 2.9 Viscous water (Note 5) α (Note 1) Eastman Kodak Manufacturing Membrane Aid (Note 2) Thickener manufactured by Asahi Denka Kogyo Co., Ltd. (Note 3) Kao (Shares) ) Thickener (Note 4) Carbon black dispersion manufactured by Mikuni Dye Co., Ltd. (Note 5) Add viscous water so that the viscosity of the coating is around 210 cps (30 ° C BL type viscometer 60 rpm).

Evaluation method of paint physical properties (A) Kosawa Paint cold-rolled steel sheet bright (SPCC ・ B70 × 150 × 0.8m
m) using a spray gun with a diameter of 2.0 mm, spray pressure 2 kg /
Spray 60 cm gloss of the coated surface obtained by spraying so that the coating thickness is 20 to 30 μm in cm ² and drying for 24 hours at 20 ° C., 65% RH unless otherwise noted. The measurement was performed using a digital variable angle gloss meter UGV-4D manufactured by Suga Test Instruments Co., Ltd.

(B) Water resistance (A) With respect to a coated plate prepared by the same procedure as described in the section of gloss, after sealing the part other than the coated surface with paraffin,
It was immersed in water at 20 ° C for 24 hours, and the appearance such as whitening of the coated surface and the state of blister was visually judged.

(C) Salt spray resistance (A) Gloss of a coated plate prepared by the same procedure as described in the section of "5. Spray water. The appearance was visually evaluated after spraying salt water for 48 hours.

(D) Tare paint is a tin plate (0.3 ×) specified in JIS G-3303 (STE).
200 × 300 mm) spray gun with a 2.0 mm diameter spray gun at a spray pressure of 2.0 kg / cm ² to a coating thickness of 20 to 30 μm and hold it vertically at 20 ° C. and 65% RH. The sagging condition of the film was visually judged.

(E) Particle size of water-dispersible resin The average particle size of the water-dispersible resin composition obtained by emulsion polymerization is DYNAMIC LIGHT SCATTERING SPECT manufactured by Otsuka Electronics Co., Ltd.
It was measured using ROPHOTOMETER DLS-700.

Example 1 4.19 parts by weight of water and a reactive emulsifier (Eleminol JS-2 manufactured by Sanyo Kasei Co., Ltd.) represented by the general formula 2 in a reaction vessel equipped with a thermometer, a stir bar, a reflux condenser and a dropping funnel 317.
Add 1 part by weight and raise the temperature to 75 ° C. On the other hand, in 221 parts by weight of water, the reactive emulsifier represented by the general formula 2 (Eleminol JS
-2 Sanyo Chemical Industry Co., Ltd.) 6.0 parts by weight and 7 parts by weight of polyoxyethylene nonylphenyl ether (HLB 16) having an ethylene oxide addition mole number of 30 were added and dissolved, and 300.77 parts by weight of methyl methacrylate was added thereto. , 2-ethylhexyl acrylate 111.25 parts by weight, methacrylic acid 2
440.69 parts by weight of the mixed monomer of 8.67 parts by weight is added, well stirred and well emulsified, and this is put in a dropping funnel. Next, 33.73 parts by weight of this emulsion was transferred to a reactor and 10
Add 8.5 parts by weight of potassium persulfate aqueous solution at 80% by weight
After the temperature is raised to 10, the temperature is maintained for 10 minutes, and then the remaining emulsion and 50.0 parts by weight of a 3% by weight aqueous potassium persulfate solution are uniformly added dropwise over 3 hours. After completion of the dropping, an aging reaction was carried out at 80 ° C. for 1 hour, followed by cooling to room temperature and adding 5 parts by weight of ammonia water for neutralization to obtain a desired water-dispersible resin composition.

Example 2 Emulsion polymerization was carried out in the same manner as in Example 1 except that 300.77 parts by weight of styrene was used as a monomer instead of 300.77 parts by weight of methyl methacrylate to obtain a desired water-dispersible resin composition.

Example 3 Emulsion polymerization was carried out in the same manner as in Example 1 except that the reactive emulsifier represented by the general formula 2 was used as the emulsifier, and the reactive emulsifier represented by the general formula 3 was used. A composition was obtained.

Example 4 Emulsion polymerization was carried out in the same manner as in Example 1 except that 282.65 parts by weight instead of 300.77 parts by weight of methyl methacrylate was used as a monomer, and 129.37 parts by weight of butyl acrylate was used instead of 111.25 parts by weight of 2 ethylenehexyl. A water-dispersible resin composition was obtained.

Example 5 Emulsion polymerization was carried out in the same manner as in Example 1 except that the reactive emulsifier represented by the general formula 2 was used as the emulsifier instead of the reactive emulsifier represented by the general formula 2, and the desired water-dispersible resin was obtained. A composition was obtained.

Example 6 Emulsion polymerization was carried out in the same manner as in Example 1 except that the reactive emulsifier represented by the general formula 2 was used as the emulsifier instead of the reactive emulsifier represented by the general formula 1, and the desired water-dispersible resin was obtained. A composition was obtained.

Example 7 300.77 parts by weight of methyl methacrylate as a monomer, 354.75 parts by weight, 2 ethylhexyl acrylate 11
Emulsion polymerization was carried out in the same manner as in Example 1 except that 1.25 parts by weight was changed to 57.27 parts by weight to obtain the desired water-dispersible resin composition.

Since the glass transition temperature of this water-dispersible resin composition by the weight fraction method is as high as 65 ° C, the paint according to the above-mentioned paint formulation is sprayed with a spray gun and put in a hot air circulation dryer at 80 ° C.
It was left for 20 minutes and dried to prepare a coated plate.

Comparative Example 1 Example 1 was repeated except that a conventional non-reactive emulsifier polyoxyethylene alkyl sulfate ammonium salt was used in place of the reactive emulsifier represented by the general formula 2 as the emulsifier.
Emulsion polymerization was carried out in the same manner as above to obtain the desired water-dispersible resin composition.

Comparative Example 2 300.77 parts by weight of methyl methacrylate as a monomer, 2-
Emulsion polymerization was carried out in the same manner as in Example 1 except that 206.01 parts by weight of methyl methacrylate and 206.01 parts by weight of 2-ethylhexyl acrylate were used instead of 117.25 parts by weight of ethylhexyl acrylate to obtain a desired water-dispersible resin composition.

Comparative Example 3 Instead of 28.67 parts by weight of methacrylic acid, 1.4 of methacrylic acid was used.
Emulsion polymerization was performed in the same manner as in Example 1 except that 3 parts by weight of ammonia water was used instead of 5 parts by weight of ammonia water added after cooling to 300.77 parts by weight of methyl methacrylate, and the desired water-dispersible resin composition. I got a thing.

Comparative Example 4 Methacrylic acid 57.34 instead of methacrylic acid 28.67 parts by weight
Emulsion polymerization was carried out in the same manner as in Example 1 except that 10 parts by weight of ammonia water was used instead of 5 parts by weight of ammonia water added after cooling to obtain a desired water-dispersible resin composition.

Comparative Example 5 The reactor described in Example 1 was charged with 317.1 parts by weight of water,
Raise the temperature to 80 ° C. On the other hand, to 221 parts by weight of water, 6.0 parts by weight of the reactive emulsifier represented by the general formula 2 and 7.0 parts by weight of polyoxyethylene nonylphenyl ether (HLB16) having an ethylene oxide addition mole number of 30 were added and dissolved, and methyl was added thereto. Methacrylate 300.77 parts by weight, 2-ethylhexyl acrylate 111.25 parts by weight, methacrylic acid 28.67 parts by weight 440.69 parts by weight of a mixed monomer are added and well emulsified,
This was added to the dropping funnel. On the other hand, 50.0 parts by weight of a 3% by weight potassium persulfate aqueous solution was added to another dropping funnel. These emulsions and potassium persulfate aqueous solution are uniformly added dropwise over 3 hours, and after completion of the addition, an aging reaction is performed at 80 ° C. for 1 hour.
After cooling to room temperature, 5 parts by weight of aqueous ammonia was added for neutralization to obtain a desired water-dispersible resin composition.

The above reaction recipe and the coating properties of the resulting water-dispersible resin composition are summarized in Table 1.

(6) Effects of the Invention The water-dispersible resin composition for rust-preventive paints of the present invention has an extremely small particle size and has an emulsifier bonded to the emulsion particles, so that it has gloss, water resistance, salt spray resistance, and sag. Excellent and extremely useful as a vehicle for anticorrosion paints.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C09D 131/06 PDT 133/06 PFY 151/00 PGZ

Claims (2)

[Claims] 1. Containing 0.1 to 10% by weight of an unsaturated carboxylic acid,
(Meth) acrylic acid alkyl ester-based copolymer obtained by emulsion polymerization of a (meth) acrylic acid alkyl ester-based monomer selected from a (meth) acrylic acid alkyl ester or a mixed monomer thereof with styrene in the presence of a reactive emulsifier. A water-dispersible resin composition of a polymer, wherein the glass transition temperature of the copolymer is 20 ° C. or higher calculated by the weight fraction method of the copolymer component excluding the reactive emulsifier component, and the water A water-dispersible resin composition for rust-preventive coatings, wherein the dispersible resin has an average particle diameter of 200 nm or less. 2. A water-dispersible resin composition for a rust preventive coating composition according to claim 1, wherein at least one emulsifier represented by the following general formulas 1 to 4 is used as the reactive emulsifier. object. (1) General formula 1 (However, R ₁ is a hydrocarbon group which may have a substituent, R ₂ is hydrogen or a methyl group, and M is Na or NH _4. ) (2) General formula 2 (However, R ₁ represents a hydrocarbon group which may have a substituent, R ₂ represents hydrogen or a methyl group, and M represents Na or NH _4. ) (3) General formula 3 (However, R ₁ represents a hydrocarbon group which may have a substituent, R ₂ represents hydrogen or a methyl group, A is an alkylene group having 2 to 4 carbon atoms, and m is a number of 0 to 100. And X is hydrogen, or a nonionic or anionic hydrophilic group.) (4) General formula 4 (However, R ₁ is an alkyl group, an alkenyl group, or an aralkyl group having 4 to 18 carbon atoms, and R ₂ is hydrogen or 4 to 4 carbon atoms.
18 alkyl group, alkenyl group, or aralkyl group, A is an alkylene group having 2 to 4 carbon atoms, or a substituted alkylene group, n is an integer of 2 to 200, M is an alkali metal atom, NH ₄ , alkanolamine residue It is a base. )