JPH05247406A - Coating resin composition - Google Patents

Abstract

PURPOSE:To provide the title composition which can improve the resistance to chipping of a vehicle such as an automobile and allows thick coating thereof. CONSTITUTION:The title composition consists of a carboxylated urethane resin emulsion and other resin emulsion and an oxazoline-base crosslinking agent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition for paint. More specifically, it relates to a resin composition for chipping-resistant rust-preventive paint for vehicles such as automobiles.

[0002]

2. Description of the Related Art Undercoat agents for vehicles such as automobiles are
In addition to rust prevention, it is required that the coating film should not be damaged by gravel impact while the vehicle is running, that is, chipping resistance. Conventionally, as a resin composition used for a chipping-resistant rust preventive coating, a chipping-resistant coating composition comprising a water-dispersible acrylic resin emulsion is known (for example, JP-A-63-10678).

[0003]

However, the conventional ones have problems that the chipping resistance is insufficient and the thick film coating property is insufficient.

[0004]

The present inventors have arrived at the present invention as a result of intensive studies to obtain a resin composition for a chipping-resistant vehicle anticorrosive coating which does not have the above problems. That is, the present invention is a resin composition for coatings, which comprises a urethane resin emulsion (A-1) having a carboxyl group and a crosslinking agent (B) having an oxazoline group.

In the present invention, the urethane resin emulsion (A-1) having a carboxyl group includes, for example, a polymer polyol (a), a compound (b) having two or more hydroxyl groups and one or more carboxyl groups, an organic compound. Emulsifying a urethane prepolymer synthesized from a polyisocyanate (c) and optionally a chain extender (d) and / or a polymerization terminator (e) in water using a salt-forming agent (f). The resulting anionic or cationic self-emulsifying emulsion is included.

In the present invention, the polymer polyol (a) used is, for example, a polyether polyol,
Mention may be made of polyester polyols, polylactone polyols, polycarbonate polyols and polyolefin polyols. As a polyether polyol,
Examples thereof include those obtained by polymerizing or copolymerizing alkylene oxides (ethylene oxide, propylene oxide, 1,2-butylene oxide, tetrahydrofuran, etc.). Specific examples of the polyether polyol include:
Polyethylene glycol, polypropylene glycol,
Examples thereof include polyoxyethylene-polyoxypropylene (block or random) glycol, polyoxyethylene-polytetramethylene ether glycol (block or random), and polytetramethylene ether glycol.

Examples of polyester polyols include dicarboxylic acids such as aliphatic dicarboxylic acids (succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid, etc.) and / or aromatic dicarboxylic acids (isophthalic acid, terephthalic acid, etc.). Dihydric alcohols (ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-
Pentanediol, neopentyl glycol, 1,4-
Dihydroxymethylcyclohexane) and the like. Specific examples of the polyester polyol include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene / butylene adipate diol, and poly-3-.
Examples include methylpentane adipate diol and polybutylene isophthalate diol.

Specific examples of the polylactone polyol include polycaprolactone diol, polycaprolactone triol, and poly-3-methylvalerolactone diol. Specific examples of the polycarbonate polyol include polyhexamethylene carbonate diol and the like. Specific examples of the polyolefin polyol include polybutadiene glycol, polyisoprene glycol, and hydrides thereof. Two or more of those exemplified as (a) may be used in combination.
Among those exemplified as these polymer polyols (a), preferred are polyether polyols, polyester polyols, polylactone polyols, and polycarbonate polyols. The number average molecular weight of the polymer polyol (a) is usually 300 to 5,000, preferably 500 to 3,000.

Examples of the compound (b) having two or more hydroxyl groups and one or more carboxyl groups include dimethylolalkanoic acid such as dimethylolacetic acid, dimethylolpropionic acid, and dimethylolbutyric acid. Preferred is dimethylolpropione. It is an acid. The amount of (b) is 0.5 to 5 as a carboxyl group in the urethane prepolymer.
%, Preferably 1 to 3% by weight. When the amount of the carboxyl group is 0.5% by weight or less, it is difficult to obtain a stable emulsion, and when it exceeds 5% by weight, the hydrophilicity becomes high, the viscosity of the emulsion becomes extremely high, and the water resistance of the coating film is lowered. ..

As the organic polyisocyanate (c),
For example, an aliphatic diisocyanate having 2 to 12 carbon atoms (excluding carbons in the NCO group), an alicyclic diisocyanate having 4 to 15 carbon atoms, an araliphatic diisocyanate having 8 to 12 carbon atoms, and an aromatic having 6 to 20 carbon atoms. Diisocyanate,
Included are isocyanurates and belet modified polyisocyanates derived from aliphatic or cycloaliphatic diisocyanates. As the aliphatic diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, etc., as the alicyclic diisocyanate, cyclohexylmethane diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, etc., as aromatic diisocyanate Is tolylene diisocyanate, α, α, α ', α'
-Tetramethyl xylylene diisocyanate, diphenyl methane diisocyanate, naphthylene diisocyanate, xylylene diisocyanate, etc. are mentioned. You may use together 2 or more types of these. Among these, preferred are aliphatic diisocyanates and alicyclic diisocyanates, and particularly preferred are hexamethylene diisocyanate, cyclohexylmethane diisocyanate and isophorone diisocyanate. Isocyanurates and burette modified polyisocyanates derived from aliphatic or cycloaliphatic diisocyanates can likewise be used as preferred.

The chain extender (d) optionally used includes low molecular weight polyols and polyamines.
Examples of the low molecular weight polyol include glycols and their alkylene oxide low molar adducts (number average molecular weight less than 500), bisphenol alkylene oxide low molar adducts (number average molecular weight less than 500), and trivalent, which are mentioned as the raw materials of the above polyester polyols. Examples thereof include alcohols (glycerin, trimethylolethane, trimethylolpropane, etc.) and alkylene oxide low molar adducts thereof (number average molecular weight less than 500). Examples of polyamines include aliphatic polyamines (ethylenediamine, N-hydroxyethylethylenediamine, tetramethylenediamine, hexamethylenediamine, diethylenetriamine, etc.), alicyclic polyamines (4,4′-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, isophorone). Diamines), aliphatic polyamines having an aromatic ring (xylylenediamine, α, α, α ′, α′-tetramethylxylylenediamine, etc.), aromatic polyamines (4,4′-diaminodiphenylmethane, tolylenediamine, Benzidine, phenylenediamine, etc.) and the like. You may use together 2 or more types of these. The amount of the chain extender (d) is usually 30.0% by weight or less, preferably 0.5 to 20.0% by weight, based on the polymer polyol (a).

Further, as a polymerization terminator (e) which is optionally used, a low molecular weight monoalcohol (methanol,
Butanol, cyclohexanol, etc.), alkyl monoamines (mono- and di-ethylamine, mono- and di-
Butylamine etc.), alkanolamines (mono- and di-ethanolamine etc.) and the like.

Examples of the salt-forming agent (f) include trialkylamines (trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, tri-amine).
n-butylamine, etc.), N-alkylmorpholines (N
-Methylmorpholine, N-ethylmorpholine, etc.), N-
Examples thereof include dialkylalkanolamines (N-dimethylethanolamine, N-diethylethanolamine, etc.). You may use together 2 or more types of these. Among these, trialkylamine is preferable, and triethylamine is particularly preferable. The amount of the salt-forming agent (f) added is usually 0.3 to 1.0 equivalent, preferably 0.4 to 0.8 equivalent, relative to 1 equivalent of the carboxyl group of (b) used.

The urethane resin emulsion (A-1) is prepared in the presence or absence of an organic solvent as described above (a), (b),
(C) If necessary, (d) and / or (e) are reacted by a one shot method or a multi-step method to form a carboxyl group-containing polyurethane resin, and after (f) is neutralized or mixed with water while being neutralized. To form a dispersion, which is adjusted by removing the solvent if necessary, and has an average particle size of 0.
It is an aqueous dispersion of a self-emulsifying polyurethane resin of about 001 to 1.0 μm. Polyurethane formation reaction is usually 20
-150 degreeC, Preferably it is 50-120 degreeC (however, when reacting an amine, it is 80 degreeC or less normally, Preferably it is carried out at 0-60 degreeC). To accelerate the reaction,
Amine-based or tin-based catalysts used in ordinary urethanization reaction (specifically, dioctyltin dimaleate, dibutyltin dilaurate, stannous octylate, dibutyltin oxide, bis (tri-n-butyltin oxide), etc.) May be used. When a solvent is used, it is particularly preferably water-soluble and has a boiling point not higher than that of water (specifically, acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, and two or more of these may be used in combination).

The cross-linking agent (B) having an oxazoline group is a compound usually having two or more oxazoline groups, and a specific example thereof is an acrylic styrene emulsion type polymer cross-linking agent having an oxazoline group [eg, polymer cross-linking agent]. Agent Epocros K series (manufactured by Nippon Shokubai Kagaku Co., Ltd.)].

Examples of the resin emulsion (A-2) include acrylic resin emulsion, vinyl acetate resin emulsion, ethylene vinyl acetate copolymer resin emulsion, polyester resin emulsion, acrylate latex and styrene butadiene latex. An acrylic resin emulsion is one in which acrylic resin particles are uniformly dispersed in an aqueous medium, and is obtained by emulsion polymerization using an acrylic monomer and a known polymerization catalyst in an aqueous solution of a dispersion stabilizer. Be done. Examples of the dispersion stabilizer include nonionic surfactants such as polyoxyethylene nonyl phenyl ether, anionic surfactants such as polyoxyethylene alkyl allyl ether sulfate ester salt, and a number average molecular weight of 5 with an acid value of about 20 to 150. A water-soluble resin such as acrylic resin of about 1,000 to 30,000 is used. Acrylic monomers used in emulsion polymerization include (meth) acrylates of aliphatic alcohols having 1 to 14 carbon atoms, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, octyl (meth) acrylate, 2
-Ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, linear or branched natural or synthetic (oxo method, Ziegler method, etc.) alcohol ( (Meth) acrylates; (meth) acrylates of alicyclic alcohols such as cyclohexyl (meth) acrylate, (meth) acrylates of aromatic alcohols such as benzyl (meth)
Acrylate etc. are mentioned. Of these, preferred are (meth) acrylates of aliphatic alcohols having 1 to 10 carbon atoms, and particularly preferred are (meth) acrylates of aliphatic alule having 1 to 8 carbon atoms. You may use these 2 or more types together.

These acrylic monomers may be used in combination with other copolymerizable monomers. As such a monomer, a monomer having a reactive functional group, for example, a carboxy group is included. Vinyl monomer [(meth) acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, etc.]; Vinyl monomer having a hydroxyl group [hydroxyethyl (meth) acrylate, hydroxylpropyl (meth) acrylate, etc.]; Vinyl monomers having an amide group [(meth) acrylamide etc.]; vinyl monomers having an epoxy group [glycidyl (meth) acrylate etc.]; vinyl monomers having a methylol group [N-methylol acrylamide etc.] Examples include monoethylenically unsaturated monomers. Two or more of these examples may be used in combination. Further, a monomer having a non-reactive functional group, for example, an aromatic monomer (styrene, vinyltoluene, etc.); a monomer having an allyl group (allyl acetate, etc.); a monomer having a nitrile group [(meth Acrylonitrile etc.]; halogen-containing vinyl or vinylidene type monomers (vinyl chloride, vinylidene chloride etc.); vinyl ester type monomers (vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatate etc.); vinyl ether type monomers And the like (eg, vinyl ethyl ether, vinyl propyl ether, vinyl isobutyl ether), etc. These exemplified compounds may be used in combination of two or more. In the monomer, a vinyl monomer having a carboxy group, a vinyl monomer having a hydroxyl group and a vinyl monomer having an amide group are used. Acrylic acid, hydroxyethyl acrylate and acrylamide are particularly preferable as the monomer, and vinyl ester monomers are particularly preferable as the monomer having a non-reactive functional group, and acetic acid is particularly preferable. Vinyl and vinyl propionate.

The vinyl acetate resin emulsion contains the above-mentioned vinyl ester-based monomer and is a known emulsifier (such as dioctyl sulfosuccinate soda), protective colloid (such as partially saponified polyvinyl alcohol), catalyst (such as hydrogen peroxide). , An accelerator (such as sodium bicarbonate), a regulator (such as acetaldehyde) and water, and is obtained by emulsion polymerization.

An example of a method for producing an ethylene vinyl acetate copolymer resin emulsion is found in the following patent [West German Patent 112:
7085 (1962), JP-A-38-8988],
Those having a carboxyl group as a functional group are preferable,
A commercially available product can be used.

The polyester resin emulsion is a high molecular weight polyester, and the following (1) to (4)
A resin emulsion obtained by dispersing a high molecular weight polyester having at least one kind of functional group represented by in the side chain in water is exemplified. (1) COOX (2) SO ₃ X (3) P = O (O
X) ₂ (4) OH (X represents H, alkali metal, alkaline earth metal or organic amine)

The acrylate latex and the styrene butadiene latex preferably have a carboxyl group as a functional group, and commercially available products can be used.

The resin composition for a vehicle anticorrosive paint of the present invention comprises resin emulsions (A-1), (B) and (A-2).
The main component of the composition is a paint formed by a known method using this composition, and the composition is applied to the electrodeposition-coated steel sheet, the plating-coated steel sheet, and the top coating surface of a vehicle such as an automobile.

The mixing ratio of each component constituting the composition of the present invention is such that the solid content of the urethane resin emulsion (A-1) is 10 parts.
Based on 0 parts by weight, other resin emulsion (A-
The amount of 2) used is usually 10 to 90 parts by weight (solid content), preferably 20 to 80 parts by weight (solid content). If it is less than 10 parts by weight, cracking and pinholes will be generated during baking after coating a thick film, and if it exceeds 90 parts by weight, the chipping resistance will be poor.
The amount of the crosslinking agent (B) having an oxazoline group is the carboxyl group, hydroxyl group, sulfonic acid group and phosphoric acid group contained in the urethane resin emulsion (A-1) and / or other resin emulsion (A-2). Is usually 0.3 to 5.0 equivalents, preferably 0.5 to 4.0 equivalents
It is equivalent. If it is less than 0.3 equivalents, the chipping resistance becomes poor, and if it exceeds 5.0 equivalents, the baked coating film becomes brittle and the chipping resistance becomes poor.

When the composition of the present invention is used as a paint, it usually contains a filler. As the filler, those conventionally used can be used. For example, powdery materials such as talc, calcium carbonate, diatomaceous earth, mica, kaolin, barium sulfate, graphite, alumina, iron oxide, titanium oxide and silica are used. As a color pigment,
Carbon black, metal chromate, metal phosphate, metal metaborate, etc. may be contained. Furthermore, if necessary, various pigment dispersion stabilizers, thickeners, leveling agents,
An antifoaming agent or the like can also be included.

The resin composition for a vehicle anticorrosive paint of the present invention can be applied to an electrodeposition coated steel plate, a plating coated steel plate and a portion on the inner or upper coating surface by an airless method, a spray method, a dipping method or a roll coating method. A method such as brush coating can be used.

The coating film thickness of the resin composition for vehicle anticorrosive paint of the present invention on the above-mentioned coated surface is usually 0.1 to 2 mm.
After that, heat treatment is performed, and the temperature in that case is usually 80 to 1.
The temperature is 20 ° C. and the time is 20 to 40 minutes.

[0027]

EXAMPLES The present invention will be further described below with reference to test examples, but the present invention is not limited thereto. Parts in the test examples are parts by weight. Test Example 1 (1) 335 parts of polycaprolactone diol (manufactured by Union Carbide Japan Co., Ltd .: TONE-0210, molecular weight 830), 7.6 parts of ethylene glycol, 22 parts of dimethylolpropionic acid were placed in a glass pressure-resistant flask having an internal capacity of 2 L.
235 parts of cyclohexylmethane diisocyanate, 400 parts of methyl ethyl ketone and 0.05 parts of dibutyltin dilaurate were charged. After substituting the inside of the system with nitrogen gas with stirring, the system was gradually heated to 90 ° C. and then reacted at 90 ° C. for 5 hours to obtain a methyl ethyl ketone diluted prepolymer having an NCO content of 1.7%. Thereafter, the mixture was cooled to 50 ° C., 10 parts of triethylamine was charged, and a quaternization reaction was carried out at 50 ° C. for 1 hour. To a separately prepared 3 L glass separable flask, 814 parts of warm water at 40 ° C. was charged, and 900 parts of the methyl ethyl ketone diluted prepolymer obtained above was gradually added dropwise to the mixture to emulsify, and then chain extension was carried out at 50 ° C. for 3 hours. The reaction was carried out. Then, methyl ethyl ketone was collected under reduced pressure by gas chromatography until the content of methyl ethyl ketone was 100 ppm or less, to obtain a resin emulsion (A-1) having a solid content of 40%. (2) The acrylic copolymer resin 4 of another resin emulsion (A-2) is added to 45 parts of the above resin emulsion (A-1).
5 parts (Hoechst Synthetic Co., Ltd .: Movinyl DM772, solid content 46%) and 15 parts of a polymer crosslinking agent containing an oxazoline compound as a crosslinking agent (Nippon Shokubai Co .: K-1010).
E, solid content 40%) were mixed. (3) The mixture was made into a coating material and defoamed under reduced pressure by a known method to prepare a coating material having PWC of 80% and NV of 70%. (4) The coating is applied to a cationic electrodeposition coated steel sheet to a thickness of 0.
The coating was applied so as to have a thickness of 3 to 0.5 mm, air-dried at 25 ° C. for 15 minutes, and then heat-treated at 90 ° C. for 30 minutes. As a result, a coating having excellent adhesion was obtained. Further, the adhesiveness of this product was not changed after being immersed in warm water at 40 ° C. for 10 days.

Test Example 2 335 parts of the polycaprolactone diol used in Test Example 1 (1) were replaced with 318 parts of tetramethylene glycol (PTMG-1000, MW 1000, manufactured by Mitsubishi Kasei Co.) and 7.6 parts of ethylene glycol. A paint was prepared in the same manner as in Test Example 1 except that 24.7 parts of 6-hexanediol was replaced.

Test Example 3 Resin emulsion (A-2) used in Test Example 1 (2)
A coating composition was prepared in the same manner as in Test Example 1, except that 45 parts of the acrylic copolymer resin of No. 1 was replaced with 45 parts of an ethylene vinyl acetate copolymer emulsion having a carboxy group (Denka EVA39, solid content 53%). did.

Test Example 4 Resin emulsion (A-2) used in Test Example 1 (2)
45 parts of acrylic copolymer resin of 45 parts of functional group-containing polyester emulsion (manufactured by Takamatsu Yushi Co., Ltd .: PES Resin 360
A coating material was prepared in the same manner as in Test Example 1 except that A, solid content 30%) was used.

Comparative Test Example 1 Resin emulsion (A-1) used in Test Example 1 (2)
45 parts of the urethane resin emulsion of 39 parts of acrylic copolymer resin (manufactured by Hoechst Synthetic Company: Movinyl DM772,
A coating material was prepared in the same manner as in Test Example 1 except that the solid content was changed to 46%.

Comparative Test Example 2 Resin emulsion (A-1) used in Test Example 1 (2)
45 parts of urethane resin emulsion of 45 parts of styrene butadiene latex (manufactured by Zeon Corporation: NipolL
X-432A, solid content 41%) was used to prepare a coating material in the same manner as in Test Example 1.

Comparative Test Example 3 15 parts of a polymer crosslinking agent containing the oxazoline compound of the resin emulsion (B) used in Test Example 1 (2) (K-1010E manufactured by Nippon Shokubai Co., solid content 40%) was not used. A coating material was prepared in the same manner as in Test Example 1 except for the above. Table 1 shows the results of evaluation of coating film characteristics of the coating compositions of Test Examples and Comparative Test Examples.

[0034]

[Table 1]

(Note) Performance evaluation items XA: presence of blisters and cracks after baking XB: chipping resistance, initial impact test (-20 ° C.) DuPont, 6 mm (1/4 inch), 1 kg, 50 cm XC: 40 Impact test after immersion in warm water at ℃ × 10 days (-20 ℃)
DuPont, 6mm (1/4 inch), 1Kg, 50c
m XD: Impact test after salt spray for 300 hours (-20 ° C) DuPont, 6 mm (1/4 inch), 1 Kg, 50 cm XE: Maron mechanical stability test, load 10 Kg, rotation speed 1
000 rpm x 5 minutes Resin residue%, 5% or less good, 5-10% somewhat good, 10
% Or more defective

[0036]

The present invention has the following effects. (1) The composition of the present invention has excellent chipping resistance and chipping resistance after water resistance, and enables thick film coatability. (2) Conventionally, a resin emulsion-based resin composition for chipping rust-resistant rust paint used for this purpose is an improved version of the above-mentioned insufficient performance. (3) The paint baking temperature is 30 to 50 ° C higher than the conventional one.
It is possible to lower it. Therefore, the heat energy at the time of baking the paint is greatly reduced, and the industrial merit is very large. (4) The resin composition for a vehicle anticorrosive paint of the present invention can also be used as an undercoating agent for automobiles, and has become a problem with conventional PVC plastisol composition-based undercoating agents and the like. It is also expected to be effective against pollution of the global environment (acid rain) due to the generation of chlorine gas. (5) The resin composition for vehicle anticorrosive paint of the present invention can be applied to various industrial uses as an adhesive, sealant, paint, etc.
In particular, it is useful as a resin composition for rust preventive paints for car body body sealers, undercoatings, fuel tanks, etc., which have been subjected to cationic electrodeposition coating and plating coating on the undercoat of automobiles.

Claims (3)

[Claims] 1. A resin composition for coating material comprising a urethane resin emulsion (A-1) having a carboxyl group and a crosslinking agent (B) having an oxazoline group. 2. Another resin emulsion (A-2)
The composition according to claim 1, which comprises: 3. A resin composition for vehicle anticorrosive paints, which comprises the composition according to claim 1.