JP3385436B2 - Water-based paint composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolymer of a phosphoric acid ester-modified epoxy resin and a carboxyl group-containing ethylenically unsaturated monomer which can be converted into water with a basic substance. The present invention relates to a water-based coating composition containing a solubilized water-soluble resin as an essential component, and particularly to a water-based coating composition that produces a coating film having excellent water resistance and corrosion resistance. 2. Description of the Related Art In recent years, regulations on the concentration of organic solvents in paints have been increasing. The resin forms currently used in water-based paints include an emulsion type and a water-soluble type.
Since the emulsion type uses a large amount of a hydrophilic emulsifier, these remain in the coating film after the formation of the coating film, and have a disadvantage of deteriorating physical properties such as water resistance. The water-soluble type generally needs to have a high acid value in order to make it water-soluble. However, when the acid value is high, there is a disadvantage that water resistance is poor, and when the acid value is low, there is a problem that stability is poor. A phosphoric acid-modified epoxy resin is known as a method for remedying these drawbacks, and although the water resistance is improved by this, there is a drawback that the stability of the paint is remarkably poor. [0003] The present invention solves the above-mentioned problems and provides an aqueous coating composition having good paint stability and excellent water resistance of the coating film. is there. SUMMARY OF THE INVENTION The gist of the present invention is to provide a
70-95% by weight of enol type epoxy resin and phenol
Novolak type epoxy resin 5 to 30% by weight epoxy resin
Fat and monohydroxyphosphoric acid diester as main components
A reaction product with a phosphoric acid ester having an acid value of 5 mg KO
H / g or less, phosphorus content 1 to 8%, oxirane oxygen content
Yes weight phosphate ester modified epoxy resin (a) 50 to 90 parts by weight 0.2% or less, the carboxyl group-containing ethylenically unsaturated monomer (b) 10 to 50 parts by weight and the acid value
Copolymerized to be in the range of 30~80mgKOH / g triethylamine carboxyl groups of the copolymer product obtained <br/>
Obtained neutralized with down water-soluble resin (A), the aqueous thermosetting resin (B), an aqueous coating composition comprising及beauty hardening agent (C), the water-soluble resin (A) To water-based coating composition 1
An aqueous coating composition characterized by containing 2 to 20 parts by weight per 00 parts by weight. That is, in the present invention, the epoxy resin is modified with a phosphoric acid ester to improve the adhesion, and the acid value is adjusted to 5 mgKOH / g or less and the oxirane oxygen content to 0.2% in order to further improve the stability of the paint. Reduced to below, copolymerized with a carboxyl group-containing ethylenically unsaturated monomer , and neutralized with triethylamine, which is a basic substance, to provide good stability and excellent water resistance. Thus, it is possible to obtain a water-based coating composition that gives the coating film properties such as water resistance and corrosion resistance. Hereinafter, the present invention will be described in detail. [0005] Epoxy resins used in the present invention, mixing the epoxy resin der of bisphenol type and novolac
You. As the bisphenol type epoxy resin, a diglycidyl ether type of bisphenol A type and bisphenol F type is preferable. The molecular weight of the epoxy resin can be in the range of about 312 to about 10,000. If the molecular weight is large, the phosphorus content of the phosphate-modified compound is reduced, and the effect of the present invention is reduced. Preferably, the molecular weight range is about 312 to 2,000. As the novolak type epoxy resin, phenol novolak, orthocresol novolak, alkylphenol novolak and the like can be used, and phenol novolak type is preferable. The mixing ratio of the bisphenol epoxy resin and the novolak epoxy resin is 7
It is preferably in the range of 0:30 to 95: 5% by weight. When the novolak type epoxy resin is less than 5% by weight, the improvement of water resistance and corrosion resistance is not sufficient,
This is because in the above case, gelation occurs during the phosphoric acid ester reaction. As the preferred phosphoric acid ester used in the present invention, monohydroxyphosphoric acid diester is desirable, but a mixture with dihydroxyphosphoric acid monoester can also be used. Examples of the phosphate ester include dibutyl phosphate, dioctyl phosphate, monoisodecyl phosphate, di (2-ethylhexyl) phosphate, ethyl acid phosphate, butyl acid phosphate, isopropyl acid phosphate,
Isodecyl acid phosphate, tridecanol acid phosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, β-chloroethyl acid phosphate, heptyl acid phosphate, (2-hydroxyethyl methacrylate)
Acid phosphate and the like, but are not limited thereto. The reaction for adding a phosphate to the epoxy resin of the present invention is preferably carried out with the acid equivalent of the phosphate being within the range of 0.2 to 0.9 per equivalent of the epoxy group. If it is less than 0.2, the phosphorus content will be low, and if it is more than 0.9, unreacted phosphoric acid ester will remain to increase the acid value. The reaction temperature is 50 to 150.
C., preferably at 80 to 120 ° C., gradually add the phosphoric acid ester to the heated epoxy resin in 30 minutes to 2 hours so that the acid value becomes 1 mgKOH / g or less.
Let react for ~ 10 hours. The phosphorus content of the adduct is preferably 1 to 8%, and if it is 1% or less, the corrosion resistance is poor, and if it is more than 8%, it is not so good. When the acid value is 10 mgKOH / g or more, the storage stability as a water-based coating composition is poor.
/ G, preferably 5 mgKOH / g or less. The reaction is preferably carried out without a solvent, but a solvent may be used. When a phosphate-modified epoxy resin and a carboxyl group-containing ethylenically unsaturated monomer are copolymerized, as described below, if a hydrophilic solvent is used as the solvent to be used, it is necessary to change the solvent in the next step. Is preferred because there is no If a large amount of epoxy groups remain after the reaction, an ester-type graft having poor hydrolysis resistance occurs when copolymerized with the carboxyl group-containing ethylenically unsaturated monomer, so that the oxirane oxygen content after the reaction is 0.2%. % Is preferred. As a means for reducing such oxirane oxygen content, after copolymerizing a phosphate ester-modified epoxy resin and a carboxyl group-containing ethylenically unsaturated monomer, the copolymer is reacted with a tertiary fatty acid. preferable. This reaction can be reduced to 0.2% or less by adding 0.5 to 1.0 mol of a tertiary fatty acid to the remaining epoxy groups and reacting at 100 to 180 ° C. for 1 to 10 hours. . [0008] Copolymerization of the phosphate-modified epoxy resin of the present invention with a carboxyl group-containing ethylenically unsaturated monomer means that the carboxyl group-containing ethylenically unsaturated monomer is added to the phosphate ester-modified epoxy resin by a conventional method. Is the addition polymerization of a monomeric product, specifically, the addition of a carboxyl group-containing ethylenically unsaturated monomer to a phosphate-modified epoxy resin in the presence of a free radical generator in an organic solvent solution It is. The carboxyl group-containing ethylenically unsaturated monomer used in the present invention contains a monoethylenically unsaturated carboxylic acid containing a carboxyl group such as acrylic acid, methacrylic acid or fumaric acid as an essential component, It may contain a carboxyl group-containing ethylenically unsaturated monomer, and forms a water-dispersible salt by copolymerization with an epoxy resin.
Acrylic acid and / or methacrylic acid must be contained at least 3% or more in all ethylenically unsaturated monomers in order to make them water-soluble. Unsaturated monomers other than acrylic acid or and methacrylic acid include methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate,
Acrylates such as isoamyl acrylate, 2-ethylhexyl acrylate, decyl acrylate and the like, and alkyl esters of methacrylic acid corresponding thereto,
Styrene, vinyltoluene, 2-methylstyrene, t-
Styrene-based monomers such as butylstyrene, hydroxyethyl acrylate, hydroxyethyl methacrylate, polyethylene glycol monomethacrylate, hydroxypropyl acrylate, hydroxypropyl-containing monomers such as hydroxypropyl methacrylate, N-methylolacrylamide, methylol groups such as dimethylolacrylamide The monomer can be selected from one or more of a monomer containing, an alkoxymethyl group-containing monomer such as N-butoxymethylacrylamide, an epoxy group-containing monomer such as glycidyl acrylate and glycidyl methacrylate, and acrylonitrile. The free radical generator used in the present invention includes, for example, benzoyl peroxide, perbutyl octate, t-butyl hydroperoxide, azobisisobutyronitrile and the like, and particularly preferred is benzoyl peroxide. It is an oxide. These are used as at least 1.5% by weight or more of all the ethylenic monomers. Examples of hydrophilic organic solvents that can be used in the copolymerization of the present invention include alkyl alcohols such as methanol, ethanol, propanol, and butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, and diethylene glycol. Examples include ether alcohols such as monomethyl ether and diethylene glycol monoethyl ether, and ether esters such as ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate. Inert organic solvents that do not mix with water can also be used, for example, aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, and ketones such as acetone and methyl ethyl ketone. Preferably, these organic solvents can be removed by distillation under normal pressure or reduced pressure. In the copolymerization of the present invention, it is preferable to use 50 to 90% by weight of the phosphate-modified epoxy resin (a ) and 10 to 50% by weight of the carboxyl group-containing ethylenically unsaturated monomer (b) . When the content of the modified epoxy resin is less than 50% by weight, the corrosion resistance aimed at by the present invention is insufficient, and 9
If it is more than 0% by weight, a good dispersion cannot be obtained. The copolymerization is carried out at a temperature of 40 to 200 ° C, preferably 60 to 150 ° C, for 3 to 10 hours. The acid value of the obtained copolymer product is usually from 10 to 300, particularly from 30 to 300.
Preferably it is in the range of 100 mg KOH / g. To solubilize the copolymerized product obtained in the present invention in water, a basic compound such as amine or ammonia may be added to partially or completely neutralize the carboxyl group. Examples of the compound include ammonia or triethylamine, triethanolamine, monomethylamine, monoethylamine, monomethanolamine, dimethanolamine, trimethanolamine, dimethylethanolamine, and the like. Since the effect of improvement is not sufficient, those having a boiling point of 120 ° C. or less are preferable, and triethylamine is particularly preferable. Water-based thermosetting resin used in the present invention
Examples of (B) include, but are not limited to, water-soluble or water-dispersible alkyd resins, oil-free alkyd resins, polyester resins, and acrylic resins. Further, the curing agent (C) used in the present invention
Examples thereof include amino resins and resole resins. Furthermore,
If necessary, various additives such as a coloring pigment, a rust-preventive pigment, an anti-sagging agent and a surface conditioner can be blended. The water-based coating composition of the present invention thus obtained is particularly cured by heating with an aqueous amino resin, and when the water-based thermosetting resin is an alkyd resin obtained using a drying oil or its fatty acid. Can be used as an ordinary dry paint by adding a metal dryer. The resin composition for a water-based paint of the present invention thus obtained can provide a coating film having excellent storage stability and excellent water resistance and corrosion resistance. Examples and Comparative Examples Hereinafter, the present invention will be described in detail with reference to examples, but it is needless to say that the present invention is not limited to these examples. The “parts” are parts by weight unless otherwise specified. Production Example 1 A reaction vessel equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with YD-128 (bisphenol A type liquid epoxy resin manufactured by Toto Kasei Co., epoxy equivalent = 187 g / eq).
00 parts and YDPN-638 (a phenol novolak type epoxy resin manufactured by Toto Kasei Co., Ltd., epoxy equivalent = 178 g / e)
q) Add 200 parts and heat to 100 ° C., then dibutyl phosphate (acid value = 264 mg KOH / g) 804.5
Was added dropwise over 1 hour and the reaction was continued for another 6 hours. Furthermore, neo acid (Exxon Chemical Co., Ltd., acid value = 321 mgKOH /
g) 95.6 parts and 0.1 part of triphenylphosphine as a catalyst were charged and reacted at 150 ° C. for 8 hours to obtain an acid value of 3.9 mg KOH / g and an oxirane oxygen content of 0.03.
%, A phosphate ester-modified epoxy resin having a number average molecular weight of 2,500. Ethylene glycol monobutyl ether 7 was added to 320 parts of the above phosphate-modified epoxy resin.
0.6 part was added and dissolved by heating to 115 ° C., and a mixture of 23.0 parts of methacrylic acid, 57 parts of methyl methacrylate and 6.5 parts of 75% benzoyl peroxide was heated to a temperature of 1 in a reaction vessel.
After dropwise addition over 2 hours while maintaining the temperature at 15 to 120 ° C., the reaction was further continued at the same temperature for 2 hours to obtain a copolymer having an acid value of 42 mgKOH / g. Next, 41 parts of ethylene glycol monobutyl ether was added, and the mixture was heated to 80 ° C., and 33.3 parts of triethylamine was added dropwise over 1 hour, and 202.3 parts of ion-exchanged water was added dropwise over 2 hours, and the viscosity was 950 cp.
A water-soluble resin having s / 25 ° C. and PH = 6.7 was obtained. Production Example 2 240 parts of a modified resin described in Production Example 1 having an acid value of 3.9 mg KOH / g, an oxirane oxygen content of 0.03%, and a number average molecular weight of 2,500, and 37.5 parts of n-butyl alcohol,
112.5 parts of ethylene glycol monobutyl ether was placed in a reaction vessel and dissolved at 115 ° C., and then 17.3 parts of methacrylic acid, 9.1 parts of styrene monomer, 0.3 parts of ethyl acrylate, and 75% benzoyl peroxide 2.4 parts of the mixture was added dropwise over 2 hours, and the mixture was further reacted at the same temperature for 2 hours to obtain a copolymer having an acid value of 60 mgKOH / g. Next, the mixture was cooled to 85 ° C., and 27.7 parts of triethylamine and 5 parts of ion-exchanged water were added.
60 parts were added and mixed, viscosity = 870 cps / 25 ° C.
A water-soluble resin having a pH of 7.4 was obtained. Production Example 3 YD-128, 186 parts and ethylene glycol monobutyl ether, 70 parts, were placed in the same reaction vessel as in Production Example 1, heated to 100 ° C., and then butyl acid phosphate (acid value = 437 mg KOH). / G) After dropping 93 parts in 30 minutes, the mixture was reacted at 100 ° C. for 2 hours, and the acid value was 99.4 mgK.
A modified resin having OH / g, oxirane oxygen content = 0.4%, and number average molecular weight = about 1200 was obtained. Next, after cooling to 80 ° C., 48.5 g of dimethylethanolamine and 264 g of ion-exchanged water were added dropwise, and the pH = 8.2 and the viscosity = 64 cp.
s / 25 ° C., resin content = 50%, solvent content = 10%, moisture =
40% of a colorless transparent water-soluble resin was obtained. Example 1 Aqueous acrylic resin (Amatex W911 manufactured by Mitsui Toatsu Co., Ltd. as solid content of 33.3 as a water-based thermosetting resin)
Part, titanium oxide as pigment (Taipaek R manufactured by Ishihara Sangyo Co., Ltd.)
830), 13 parts of an amino resin (Cymel 303 manufactured by Mitsui Cyanamid Co.) as a curing agent, and Production Example 1
10 parts by weight of the water-soluble resin obtained in the above, and 0.3 part of an amine salt of p-toluenesulfonic acid (4040 manufactured by Mitsui Cyanamid Co.) as a catalyst were added thereto to obtain an aqueous paint. Example 2 A paint was prepared in the same manner as in Example 1 except that the water-soluble resin obtained in Production Example 2 was used, to obtain a paint of Example 2. Comparative Example 1 A coating material was prepared in the same manner as in Example 1 except that the water-soluble epoxy resin was not added, and a coating material of Comparative Example 1 was obtained. Comparative Example 2 A coating material of Comparative Example 2 was obtained in the same manner as in Example 1 except that the water-soluble resin obtained in Production Example 3 was used. Table 1 shows the results of evaluating the stability and physical properties of the coatings prepared in Examples and Comparative Examples. The test method is as follows. -Stability test of paint After the paint was stored at a temperature of 40 ° C for one month, the presence or absence of separation was examined. Coating physical property test Zinc phosphate-treated steel plate, applied to a test piece of 50 × 150 × 0.3 mm with a bar coater so as to have a dry film thickness of 25 to 30 μm, and baked for 20 minutes in a dryer set at 160 ° C. . -Pencil hardness test A pencil hardness test was performed according to the pencil scratch test of JIS K5400. -Adhesion test The cross-cut tape peeling test was performed, and the results are shown in Table 1 as ○: no peeling, Δ: slight peeling, ×: full peeling. Water resistance test The coated plate was immersed in water and subjected to a hot water treatment at 100 ° C. for 2 hours, and then a cross-cut tape peeling test was performed as a state observation and adhesion test of the coating film.・ Corrosion resistance test A cross cut was made with a cutter knife to reach the base of the coating film, and after spraying 5% salt water at 35 ° C. for 240 hours,
The state of the cross cut portion was observed. The sample was evaluated as ○ when there was no abnormality in the coating film, Δ when the blister was generated, and × when the amount of the generated blister was large. Also, the rust width from the cross-cut portion was measured. ○: rust width 1 mm or less, Δ: rust width 1-2 mm, ×: 3-4
It is shown in Table 1 as mm. [Table 1] As is clear from Table 1, the water-based paint of the present invention has excellent storage stability and can provide a coating film having excellent water resistance and corrosion resistance. [0024]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-320569 (JP, A) JP-A-52-117929 (JP, A) JP-A-5-320566 (JP, A) JP-A-59-117 193970 (JP, A) JP-A-62-112603 (JP, A) JP-A-59-199711 (JP, A) JP-A-5-163330 (JP, A) JP-A-53-17641 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) C09D 1/00-10/00 C09D 101/00-201/10 C08G 59/00-59/72 C08K 3/00-13/08 C08L 1 / 00-101/16

Claims (1)

(57) [Claims] 1. Bisphenol type epoxy resin 70 to 9
5% by weight and phenol novolak type epoxy resin 5 to 3
0% by weight of epoxy resin and dihydroxy monophosphate
It is a reaction product with a phosphate ester containing
The acid value is 5 mg KOH / g or less, and the phosphorus content is 1 to 8
%, A phosphoric acid ester-modified epoxy resin (a) having an oxirane oxygen content of 0.2% or less ;
Carboxyl group-containing ethylenically unsaturated monomer (b) 10
Acid value of 30 to 80 mgKOH / g
Of the copolymerization product obtained by copolymerization
Water-soluble resin obtained by neutralizing the hydroxyl group with triethylamine
(A), an aqueous thermosetting resin (B),及Beauty hardening agent (C)
An aqueous coating composition comprising the water-soluble resin
A water-based coating composition comprising (A) in an amount of 2 to 20 parts by weight per 100 parts by weight of the water-based coating composition.