JPS58167640A - Aqueous coating composition - Google Patents

Abstract

PURPOSE:A room temperature rapid drying type aqueous coating material, obtained from a methacrylic ester monomer, and an alpha,beta-monoethylenically unsaturated carboxylic acid monomer, etc., capable of giving coating films having improved performance, e.g. corrosion resistance, water resistance, etc., and having improved coating operability and safety. CONSTITUTION:An aqueous coating composition prepared by polymerizing (A) 5-60wt% at least one methacrylic ester monomer having 8-18C long chain alkyl group with (B) 5-20wt% at least one alpha,beta-monoethylenically unsaturated carboxylic acid monomer and (C) 20-90wt% at least another copolymerizable monomer, and neutralizing the resultant polymer having 3,000-50,000 number- average molecular weight with a volatile basic substance, e.g. ammonia. Octyl methacrylate may be cited as the component (A), and (meth)acrylic acid monomer may be cited as the component (B). Styrene may be cited as the component (C).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous coating composition that dries at room temperature and has excellent coating properties such as corrosion resistance and water resistance.

In recent years, accidents such as ignitions, explosions, and solvent poisoning caused by organic solvents in paints have been increasing year by year, and the concentration of organic bath agents that volatilize into the air is being strictly regulated due to legal issues. is the current situation.

Therefore, water-based paints that do not have these drawbacks have been developed.

The water-based paints are broadly classified into emulsion type and water-soluble type. The former does not produce a glossy coating, and since a large amount of hydrophilic emulsifiers are used, and the hydrophilic groups remain in the coating, the coating has significantly poor water resistance and corrosion resistance. , its uses are limited. On the other hand, the latter, for example, water-bathable alkyd resin paints, can be dried at room temperature by adding a metal dryer, but this has the disadvantage that the drying time is long. In addition, for water-soluble acrylic resin paints with improved drying properties, the carboxyl groups of acrylic acid, etc. are neutralized with organic amines or ammonia, etc. to make salts and make them water-soluble. The problem remains, and if the molecular weight is increased to improve this problem, the viscosity increases and the workability is poor.

The inventors of the present invention have made extensive studies to improve these drawbacks, and as a result, have arrived at the present invention, which is a water-based paint that dries at room temperature and is quick-drying and has excellent water resistance and corrosion resistance.

That is, the present invention provides: (A) at least one monomer selected from methacrylic acid ester monomers having a long chain alkyl group having 8'/-18 carbon atoms, preferably having 10 to 18 carbon atoms; A methacrylic acid ester monomer having a long chain alkyl group, more preferably a methacrylic acid ester monomer having a long chain alkyl group having 12 to 18 carbon atoms 5 to 6
0m1% (hereinafter abbreviated as "CH") Preferably 10 to 50 ratio (B) At least one α,β-monoethylenically unsaturated carboxylic acid monomer, preferably methacrylic acid 5
~20ql, preferably 6-15ql) (C) at least one volume of other polymerizable monomers9
0 to 20, and the number average molecular weight is 6000 to 6000.
50,000 is neutralized with a volatile basic substance to provide an aqueous coating composition.

The aqueous coating composition of the present invention has excellent water resistance and corrosion resistance, and has good gloss coating workability and stability.

In the present invention, 5(A) methacrylic acid ester monomers having a long chain alkyl group having 8 to 18 carbon atoms include methacrylic acid octyl ester, methacrylic acid 2-ethylhexyl ester, methacrylic acid decyl ester, and methacrylic acid ester monomer. Examples include decyl ester, lauryl methacrylate, tridecyl methacrylate, myristyl methacrylate, cetyl methacrylate, and stearyl methacrylate, preferably having 10 to 18 carbon atoms, more preferably having 12 to 1 carbon atoms.
It has eight long-chain alkyl groups.

(B) α,β-monoethylenically unsaturated carboxylic acid monomer as used in the present invention refers to (meth)acrylic acid monomer, itaconic acid monomer, crotonic acid monomer, (anhydrous) maleic acid. monomers, fumaric acid monomers, etc., and methacrylic acid monomers are particularly preferred in terms of water resistance and corrosion resistance.

In the present invention, (e) other polymerizable monomers include styrene, vinyltoluene, α-methylstyrene,
Alkenyl aromatic monomers such as chlorostyrene; (meth)
Lower (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid (iso)propyl ester, (meth)acrylic acid (iso)butyl ester, (meth)acrylic acid tert-butyl ester, etc.
meth)acrylic acid 5-ester; 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, (meth)acrylate
Examples include polymerizable alcohols such as allyl alcohol.

The volatile basic substances referred to in the present invention include ammonia Q, triethylamine, diethylamine, monoethylamine, dimethylethanolamine, monoethanolamine, and the like.

In the present invention, the amount of methacrylic acid ester monomer having a long chain alkyl group of Al is 5 to 60%,
If the number of particles is less than 5, the corrosion resistance will be poor, while if it exceeds 60, the drying properties, writing hardness, etc. will be poor, which is not preferable.

Of these monomers, -methacrylic acid esters having a long chain alkyl group having 12 to 18 carbon atoms are most preferred from the viewpoint of water resistance, corrosion resistance, and adhesion of the coating film.

6- Also, the amount of α, β-unsaturated carboxylic acid monomer in (B) is 5
-20 parts, and if the amount is less than 5 parts, the water solubility and atomization of the polymer and the coating workability of the composition will be poor, while if it exceeds 20 parts, the water resistance and corrosion resistance of the coating film will deteriorate, which is not preferable. .

The number average molecular weight of the compound obtained by the addition reaction of each of the above monomers is suitably 6,000 to 50,000; if the molecular weight is less than 6,000, the corrosion resistance and water resistance of the coating film will be poor, that is, it will cause a whitening phenomenon, so it is not preferable. If it exceeds 50,000, the viscosity of the composition becomes thick and workability decreases, which is not preferable. The molecular weight is 5000 to 400
00 is preferred.

When the polymer in the composition of the invention has hydroxyl groups, crosslinking agents such as melamine resins can be added to the composition. Further, the composition of the present invention may be used in combination with additives such as pigments, leveling agents, surface conditioners, and ultraviolet inhibitors.

The composition of the present invention can be used in coating methods other than aerosol coating, such as air spray coating, airless spray coating, dip coating, paulownia coating, electrostatic coating, electrodeposition coating, and roll coater coating.

Next, the present invention will be further explained by examples.

Example 1 67 parts by weight of ethylene glycol mobutyl ether was charged into a reactor equipped with a stirrer, a cooler, a temperature control device, and a nitrogen gas inlet tube, and the temperature was maintained at 100°C under stirring in a nitrogen gas atmosphere. Meanwhile, 2 parts by weight of penzoyl baroxide, S LMA (Mitsubishi Rayon product name, lauryl methacrylate)) 45. ffi grandpa,
9 parts by weight of methacrylic acid, bunal acrylic ester (S
M: parts, 40 parts by weight of styrene, 1 part by weight of lauryl mercaptan
One part was added dropwise over a period of 4 hours. After the dropwise addition was completed, stirring was continued at the same temperature for 3 hours and cooled to 40'C, then 7 parts by weight of aqueous ammonia (25F) and 81 parts by weight of ethylene glycol monoethyl ether were added, and the non-volatile content was 40%, the number average molecular weight was Lid i3. [100 aqueous resin (I) was obtained. 60 parts by weight of this aqueous resin (I) and 25 parts by weight of carbon black]
Add i parts and 76 parts by weight of water, and mix in a ball mill for 24 hours.
Millbase (I) was obtained by mixing and dispersing for a period of time.

Next, 10 parts by weight of the above aqueous resin (I) and the millbase (I)
When 6 parts by weight were mixed, diluted with a mixed solvent of isopropyl alcohol/water to a viscosity of 30'' (Ford cup≠4), and painted by air spray, it exhibited excellent physical properties as shown in Table 1.

Example 2 In a container similar to Example 1, add 67% isopropyl alcohol.
Parts by weight were added, and the temperature was raised to 8.5 m while stirring in a nitrogen gas atmosphere.
While maintaining the temperature at 0'C, a mixture of 9 parts of benzoyl peroxide double cap, 30 parts by weight of lauryl methacrylic ester, 9 parts by weight of methacrylic acid, 13 parts by weight of butyl acrylic ester, and 48 parts by weight of styrene was added to this for 4 hours. It took a while to drip.

After the dropwise addition, stirring was continued at the same temperature for 6 hours, cooled to 40°C, 10 parts by weight of triethylamine, 65 parts by weight of isopropyl alcohol, and 75 parts by weight of water were added, and the non-volatile content was 40 parts by weight.
%, pH 9.0, and number average molecular weight 21.000.

This aqueous resin (II) was mixed with a mixed solvent of isopropyl alcohol/water to a predetermined viscosity of 30" (Ford cup 44
) and applied by air spray, it showed excellent coating performance and workability as shown in Table 1.

Example 3 Normal propyl alcohol 6 in the same container as Example 1
7 parts by weight was charged, and the mixture was stirred in a nitrogen gas atmosphere at a temperature of 1.
While maintaining the temperature at 00°C, 2 parts by weight of 10-benzoyl oxide, 20 parts by weight of stearyl methacrylate, 11 parts by weight of methacrylic acid, 17 parts by weight of styrene, 47 parts by weight of n-butyl methacrylate, and β- 5 parts by weight of hydroxyethyl methacrylate and 2 parts by weight of lauryl mercaptan were added dropwise over a period of 4 hours. After the addition, stirring was continued at the same temperature for 3 hours and cooled to 40°C.Next, 9 parts by weight of aqueous ammonia (25=1) and 80 parts by weight of isopropyl alcohol were added, and the non-volatile content was 40%.
An aqueous resin (e) having a number average molecule j#8,000 was obtained. To 60 parts by weight of this aqueous resin (II) were added 24 parts by weight of isopropyl alcohol, 49 parts by weight of water, and 25 parts by weight of carbon black, and the mixture was mixed and dispersed in a ball mill for 24 hours to obtain a mill base (n).

Next, when 10 parts by weight of the aqueous resin and 5 parts by weight of MillPace 0I were mixed, excellent physical properties were exhibited as shown in Table 1.

11- Note) Corrosion resistance (salt spray test): JIS K5400-
7.8 (48 hours) Water resistance: JIS K
54Ω0-7.2 (48 hours immersion) Acid resistance:
JIS K5400-7.5 (48 hours immersion) Salt water resistance: JIS K5400-7.6 (48 hours immersion) Dry to the touch: JIS K5400-5.8 (minutes) Curing dry: JIS K5400-5.8 (hours) ) 60 degree specular gloss: JIS K54DO-6,8 Pencil hook test: JIS K5400-6.14 Impact resistance: JIS K5400-6.13 Flexibility: JI
S K5400-6.16 Patent Applicant: Dainippon Ink & Chemicals Co., Ltd. 16-271-

Claims (1)

[Scope of Claims] (A) At least one type of methacrylic acid ester monomer having a long chain alkyl group having 8 to 18 carbon atoms 5
~60% by weight (B) At least one α,β-monoethylenically unsaturated carboxylic acid monomer
5 to 20% by weight (C) Obtained from 20 to 90% by weight of at least one other copolymerizable monomer, and has a number average molecular weight of 3,000 to 50.0
An aqueous coating composition prepared by neutralizing a polymer of No. 00 with a volatile basic substance.