JPH0455480A - thermosetting coating composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a thermosetting coating composition, and more specifically, it is used in fields such as aluminum sash, which require high cosmetic properties and coating performance, and is used to coat metals. It is used as a coating for
The present invention relates to a thermosetting coating composition suitable for electrodeposition coating that has excellent water resistance, water repellency, stain resistance, and weather resistance.

(Prior art) Conventionally, in addition to the acrylic melamine type of the present invention, thermosetting resins such as alkyd melamine type and epoxy melamine type have been used for electrodeposition paints, but acrylic melamine type in particular has excellent weather resistance. Because of its excellent film performance and appearance, it is used as a top coat in various metal coating fields.

(Problem to be solved by the invention) However, systems using ordinary acrylic copolymers have insufficient water repellency, and if the material is made of iron, where corrosion resistance is important, electrodeposition Finishing with one coat of paint has the problem of insufficient corrosion resistance and poor stain resistance.

Therefore, the purpose of the present invention is to maintain the cosmetic properties, weather resistance, hardness and flexibility of acrylic thermosetting coatings, and to improve stain resistance and corrosion resistance by copolymerizing a specific fluorine monomer. An object of the present invention is to provide a thermosetting coating composition for electrodeposition that can form an excellent coating film.

(Means and effects for solving the problems) That is, the thermosetting coating composition of the present invention comprises a thermosetting polycarboxylic acid acrylic copolymer (A) and an alkoxyalkylated melamine resin (B) as a vehicle. This relates to a thermosetting coating composition in which a metal material is electrodeposited in an electrodeposition bath and cured by heating, wherein the acrylic copolymer (A) contains (1) 0.5 to 40% by weight of fluorine; contains atoms,
+21 (a) (meth)acrylic acid ester having a fluoroalkyl group or perfluoroalkyl group 5 to 50
% by weight, (b) 10 to 50% by weight of a hydroxyl group-containing (meth)acrylic acid ester represented by the general formula (I), R'0CH2=C-C-0-R5-OH(I) (in the formula, R4 represents a hydrogen atom or a methyl group, and R5 represents a C to C6 alkylene group.) fc) Vinyl monomers 1 to 20 containing at least one functional group selected from a carboxyl group, a sulfonic acid group, and a phosphoric acid group. (d) (meth)acrylic acid ester represented by general formula (II) 15-70% by weight R' 0 CH2=C-C-0-R7(n) (wherein, R6 is a hydrogen atom or methyl (R7 represents a C3 to C2° hydrocarbon substituent.) (e) Copolymerizing 0 to 50% by weight of other vinyl monomers copolymerizable with the components (a) to (d) above. The hydroxyl value obtained is 40
~170■KOH/g, acid value 10~80■KOH/
g, weight average molecular weight is 1oooo to 1oooo.

60-90% by weight of a copolymer salt obtained by partially or completely neutralizing the acrylic copolymer (A) with a base;
It is a thermosetting coating composition containing -40% by weight and having an aqueous solvent as an essential component.

The acrylic copolymer (A) used in the thermosetting coating composition suitable for electrodeposition coating of the present invention contains 0.5 to 40 fluorine atoms.
It is contained within a range of % by weight. This can be achieved by copolymerizing (meth)acrylic acid esters containing fluorine atoms to form a (meth)acrylic copolymer.
This is to impart good water repellency and stain resistance inherent to fluororesin.

If the content of fluorine atoms is less than 0.5% by weight, the water repellency and stain resistance of the cured coating film will be low, and if it exceeds 40% by weight, problems such as foaming and repelling during coating film formation and adhesion to metal substrates may occur. This is not preferable because it reduces performance.

A more preferred range is 2 to 25% by weight. The acrylic copolymer (A) used in the present invention is the above-mentioned (a)
It is obtained by copolymerizing each component of ~(e).

The (meth)acrylic acid ester that is the (al component) is
1 or more carbon atoms, preferably 2 to 2 carbon atoms, substituted with a fluorine atom
It represents a (meth)acrylic acid ester having a fluoroalkyl group having 18 carbon atoms or a perfluoroalkyl group in the side chain, and contains 5 to 50% by weight of the total monomer component of the acrylic copolymer. However, if this proportion is less than 5% by weight, the stain resistance and water repellency will not be sufficient, and if it exceeds 50% by weight, the adhesion to the undercoat film and the metal substrate will decrease. Undesirable. Further, the secondary adhesion after the water resistance test also decreases. Preferably 5-30% by weight
It is. As the (meth)acrylic acid ester which is the component (a), for example, CH2=CHC00CH2CF
3, CH2=C(CHs)COOCf(2cFs,C
H2=CHC00CF[2CF2CH2CF,,CH2
=C(CH,)COOCH,CF2CH2CF3,CH
2= CHCOOCH2C2F5, CH,=C(CH3
)C00CH2C2F5, CH2=CHC00C)l(
CHs)CJs, CH2=C(CH3)C00CR(C
H3) C2F6, CH2=CHC00CH(CF,)!
, CH2=C(CH3)C00CR(CF,)2,CH
,=CHC00CHzCFzCHFCFs, CH2=C
(CH3)C00CH2CF2CHFCF! .

CH2=CHC00CH(CI,)CJ 7,CH,=
C(CH3)C00CH(CH3)CsFr,CH,=
CHC00CCICF,)4H,CH2=C(C)! riC00CJ(!(CF2),H,CJ(,=C)IC0
0C) 12c, F, 5, C) I2=C(CH,)C00
CH2C2F5, CH2=CHC00(C)12)2
(CF2)4F, CH2=C(1&)COO(CH
2) 2(CF, ), F, CH2=CHC00(CH2
)2(CF2),F, CH,=C(C)lC00(
CH2)2(CF,)eF, CH2=CHC00CH
2C8F+7, CH2=C(CH,)COOCH2C,
F, 7, CH2=CHC00(CH2)2C11F+7
,C)1. =C(CH3)C00(CH2)2C,F,
7, CH2=CHC00(CHz)2c+. F2.
, CH2=C(CH3)C00(CH2)2CN)F2
+ is mentioned. These may be used singly or as a mixture of two or more. These can be produced by reacting acrylic acid or methacrylic acid or their acid chlorides with fluorinated alcohols having linear or branched side chains, or by reacting fluorinated carboxylic acids with linear or branched side chains or by reacting these with fluorinated alcohols having linear or branched side chains. It can be obtained by a known synthesis method such as reacting an acid chloride with a hydroxyl group-containing vinyl monomer such as 2-hydroxyethyl (meth)acrylate or 2-hydroxypropyl (meth)acrylate.

The hydroxyl group-containing (meth)acrylic acid ester of the general formula (I) represented by the above item tb) is contained in the range of 10 to 50% by weight. If it is less than 10% by weight, the crosslinking density of the cured coating will be low (and solvent resistance and weather resistance will be reduced; if it exceeds 50% by weight, the coating will become brittle and have reduced flexibility and water resistance. Undesirable.

Specific examples of hydroxyl group-containing (meth)acrylic esters include 2-hydroxyethyl (meth)acrylate, 2-
Examples include hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, etc. You may use more than one species together.

(The vinyl monomer having at least one kind of functional group selected from a carboxy group, a sulfonic acid group, and a phosphoric acid group as shown in item C1 is contained in a range of 1 to 20% by weight.1
If it is less than % by weight, the water solubility will be insufficient, the stability of the electrodeposition bath over time will be poor, and the appearance (gloss, luster) will be low. Also,
If it exceeds 20% by weight, water resistance decreases, which is not preferable.

Specifically, carboxyl group-containing vinyl monomers such as (meth)acrylic acid, itaconic acid, fumaric acid, maleic acid, monomethyl itaconate, monobutyl itaconate, maleic acid, monomethyl maleate, and monobutyl maleate; -Sulfoethyl (meth)acrylate, vinylbenzenesulfonic acid, 2-acrylamido-2-methylpropane, sulfonic acid group-containing vinyl monomer, Light Ester PA, Light Ester PM (manufactured by Kyoeisha Yushi ■),
Examples include phosphoric acid group-containing vinyl monomers such as Kayamer PM2 and Kayamer PM21 (manufactured by Nippon Kayaku ■).

In addition, the (meth)acrylic acid ester represented by the general formula (ff) in (d1) is an essential component from the viewpoint of weather resistance, cosmetic properties, and flexibility, and is used in a range of 15 to 70% by weight. If it is less than 15% by weight, water resistance and flexibility will decrease, and if it exceeds 70% by weight, water solubility will decrease, electrodeposition bath stability will decrease, and hardness and stain resistance will also decrease.

Specific examples include ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, 5ee-butyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, phenylethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, n-octyl Examples include (meth)acrylate, tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, and FA-511A and FA-513M manufactured by Hitachi Chemical.

1. Vinyl monomers copolymerizable with components (a) to ldl shown in fe1 above are used in a range of 0 to 50% by weight, and specifically include styrene, α-methylstyrene, vinyltoluene, etc. styrene derivative; acrylonitrile,
Polymerizable unsaturated nitriles such as metacyclonitrile; N
-N-alkoxy-substituted amides such as methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, and N-butoxymethyl (meth)acrylamide; containing epoxy groups such as nigericidyl (meth)acrylate and (meth)allyl glycidyl ether; Monomers; Basic monomers such as dimethylaminoethyl (meth)acrylic acid and diethylaminoethyl (meth)acrylic acid; (meth)acrylic acid esters such as methyl methacrylate and methyl acrylate. If the amount used exceeds 50% by weight, flexibility and weather resistance will deteriorate, which is not preferable.

In addition, the type and amount of monomers fa)-(e) used in the production of the acrylic copolymer (A) are such that the acid value of the obtained acrylic copolymer (A) is 10 to 80. ■
KO) l/g, hydroxyl value is 40-170■KOH/f
, should be selected so that the weight average molecular weight is 10,000 to 100,000. If the acid value is less than 10 KOL/g, the water solubility after neutralization or partial neutralization with a basic compound will be poor, the appearance such as gloss and shine will be low, and the stability of the electrodeposition bath over time will deteriorate. This is not preferable because it reduces the

If it exceeds 80■KO)f/r, the water resistance of the cured coating film will decrease, which is not preferable. A more preferable range is 20 to 60 K
O) 17g. In addition, the hydroxyl value is 40 ■KOH/g
If it is less than 170 KO)/g, the crosslinking density of the coating film will be low, resulting in poor weather resistance and solvent resistance. This is not preferable because it lowers the temperature. Furthermore, if the weight average molecular weight is less than 10,000, water resistance and weather resistance will be insufficient;
If it exceeds 0, the cosmetic properties and stability over time as an electrodeposition coating will deteriorate, which is not preferable. A more preferable range is 1500
0 to eoooo.

Further, the thermosetting coating composition of the present invention contains 10 to 40% by weight of the alkoxyalkylated melamine resin (B) as described above.
However, if the content is less than 10% by weight, the solvent resistance and weather resistance of the cured coating film will be insufficient, and if it exceeds 40% by weight, the water resistance and flexibility of the coating film will decrease, which is not preferable.

Examples of the alkoxyalkylated melamine resin (B) include those obtained by methylolizing aminotriazine and alkyl etherifying it with cyclohexanol or an alkanol having 1 to 6 carbon atoms.

Specific examples include methoxymethylated melamine resin, ethoxymethylated melamine resin, butoxymethylated melamine resin, and methoxybutoxy mixed methylated melamine resin. More specifically, Cymel 300, Cymel 303, Cymel 325, Cymel 370, Cyinul 380, etc. manufactured by Mitsui Suyanamide■, Sumimaru M-40W, Sumimaru M-63W, etc. manufactured by Sumitomo Chemical ■; manufactured by Sanwa Chemical ■. Two types of Mll-24, MX-40
, Cymel 285 manufactured by Mitsui Suyanamide ■, Cyinul 2
6F etc.

Further, the acrylic copolymer (A) can be obtained by polymerizing each of the above-mentioned monomers, and any known method such as solution polymerization, bulk polymerization, emulsion polymerization, etc. can be adopted as the polymerization method, and in particular, Solution polymerization is preferred. When a solution polymerization method is applied, a mixture of the above-mentioned components is copolymerized in the presence of an organic solvent and a polymerization initiator. Examples of this organic solvent include isopropanol, butyl cellosolve,
Ethyl cellosolve ethanol, n-butanol, i-butanol, butyl acetate, etc. are commonly used.

As the polymerization initiator, for example, azobisisobutyronitrile, benzoyl peroxide, and cumene hydroperoxide are usually used. Furthermore, chain transfer agents such as 2-mercaptoethanol and n-dodecylmercaptan may be used as necessary.

In order to dissolve the acrylic copolymer (A) thus produced in an aqueous medium, it is used after being partially neutralized or neutralized with a basic compound. Specific examples of basic compounds include ammonia, triethylamine, diethylamine, monoethanolamine, jetanolamine, triethanolamine, N,N-dimethylaminoethanol, N,N-diethylaminoethanol, motuprobanolamine, etc. .

In producing the thermosetting coating composition of the present invention, a phosphoric acid catalyst or a sulfonic acid catalyst may be used to lower the curing temperature. Examples of these catalysts include Catalyst 4040, Catalyst 600, Catalyst 269-9, and King (Mitsui Suyanamide).
Naikure 155 and Naikure 52 manufactured by KING)
25 and Naicure 3525. Other,
Auxiliary additives such as suitable surface conditioning agents may also be added.

In addition, pigments such as titanium oxide, carbon black, quinacridone, and cyanine blue; resins other than acrylic resins such as epoxy resins, cellulose resins, and polyesters are added as necessary to color the cured coating film. Good too.

Furthermore, water is the main component of the aqueous medium used in preparing the electrodeposition paint, but a water-soluble organic solvent such as methanol, ethanol, ethyl cellosolve, butyl cellosolve may be used in combination.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, in Examples and Comparative Examples, all "r parts" indicate "parts by weight."

70 parts of isopropanol was charged into a reaction vessel equipped with a stirrer, a temperature controller, and a condenser.

The contents were heated to 80°C, and then 20 parts of styrene, 12.5 parts of methyl methacrylate, 30 parts of n-butyl acrylate, 20 parts of 2-hydroxyethyl acrylate, I
102 parts of a monomer mixture consisting of 12.5 parts of H,IH,2H,2H-nonafluorohexyl methacrylate, 5 parts of acrylic acid, 1 part of n-dodecylmercaptan, and 1 part of azobisisobutyronitrile was added dropwise to the dropwise apparatus over 3 hours. It was dripped more continuously. Then, 1 part of azobisisobutyronitrile was continuously added in small portions into the reaction vessel over a period of 2 hours. After further aging at 82° C. for 1 hour to increase the conversion rate to resin, 30 parts of isopropanol was added to complete the reaction to obtain an acrylic copolymer (A) of P-1.

Next, the combinations of the above components (a) to (e) were changed to obtain acrylic copolymers (A) of P-2 to P-12 shown in Table 1-1 and Table 1-2. .

The viscosity, nonvolatile content, and acid value of each of the 12 types of acrylic copolymer solutions P-1 to P-12 obtained were as shown in Table 1-1 and Table 1-2. .

11. Electrodeposition paints T-1 to T-12 were prepared using the above six types of acrylic copolymer solutions and according to the paint formulations shown in Table 2.

In this specific example, β-dimethylaminoethanol was added according to the acid value of 12 types of acrylic copolymers (A) to partially neutralize the polymers so that the degree of neutralization was 60%.

Next, titanium oxide (CR-95) was added in the amount shown in Table 2, kneaded in a ball mill for 24 hours, and an alkoxyalkylated melamine resin was added as shown in Table 2 to prepare a paste.

Further, an electrodeposition bath was prepared with pure water so that the solid content was 12% by weight, and the electrodeposition was applied using a phosphate-iron treated plate for 3 minutes at a distance between electrodes of 40'' and a voltage of 80V. After the coating film was air-dried for 30 minutes, it was baked at 180° C. for 30 minutes.

As is clear from the results shown in Table 3, the coating films obtained in Examples exhibit excellent gloss, water repellency, and stain resistance. In addition, in the case of Comparative Example-1, which deviates from the scope of the claims, the water repellency, stain resistance, etc. were lower than those of the Examples, and in the case of Comparative Example-2, the water repellency was very good. However, the adhesion to the object to be coated was poor, and foaming was noticeable when forming into a paint, which caused problems in paint workability.

Comparative Example 2 had a good appearance, but peeled off from the base material.

Comparative Examples 3 to 6 showed a remarkable decrease in gloss, and Comparative Example 7 had a relatively good appearance, but peeled off from the base material. Furthermore, Comparative Example 8 showed significant yellowing.

(Effects of the invention) The thermosetting coating film using the thermosetting coating composition suitable for electrodeposition coating of the present invention has excellent properties such as stain resistance, water repellency, weather resistance, and cosmetic properties. It is extremely useful for metal material applications such as , exterior use, and pre-coal metal.

same Up Nagai righteousness Procedural amendment (spontaneous) 1.Display of the incident 1990 Patent Application No. 164739 2. Name of the invention thermosetting coating composition 3. Person who makes corrections Relationship to the incident Patent applicant address Name (603) 4. Agent $101 Mitsubishi Rayon Co., Ltd. 5. Date of amendment order: Voluntary amendment 6. Subject of correction Description, detailed description of the invention 7. Contents of correction The specification and detailed description of the invention are amended as follows.

(1) On page 9, line 12, "carboxy group" is corrected to "carboxyl group."

+2+Page 11, line 17, "N-butoxymethyl (meth)acrylamide" is corrected to "N-ethoxymethyl (meth)acrylamide."

(Page 3N2, lines 3 and 4 "methyl methacrylate, methyl acrylate" is replaced with "methyl methacrylate, methyl acrylate")
I am corrected.

+4123, Table 3, bottom note) Correct the first line "Side-made digital transformation gloss needle" to "Hook-made digital variable angle gloss meter."

Claims (1)

[Claims] A thermosetting polycarboxylic acid acrylic copolymer (A),
A thermosetting coating composition in which a metal material is electrocoated in an electrodeposition bath using an alkoxyalkylated melamine resin (B) as a vehicle and cured by heating, wherein the acrylic copolymer (A) is (1)0 Contains .5 to 40% by weight of fluorine atoms, (2
) (a) 5 to 50% by weight of (meth)acrylic ester having a fluoroalkyl group or perfluoroalkyl group (b) 10 to 50% by weight of (meth)acrylic ester having a hydroxyl group represented by general formula (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) (In the formula, R^4 is a hydrogen atom or methyl group, R^5 is C_
Represents an alkylene group of 1 to C_6. ) (C) 1 to 20% by weight of a vinyl monomer containing at least one functional group selected from a carboxyl group, a sulfonic acid group, and a phosphoric acid group; (d) (meth) represented by general formula (II); Acrylic acid ester 15-70% by weight, ▲Mathematical formulas, chemical formulas, tables, etc.▼(II) (In the formula, R^6 represents a hydrogen atom or a methyl group, R^
7 represents a C_2 to C_2_0 hydrocarbon substituent. )
(e) The hydroxyl value obtained by copolymerizing 0 to 50% by weight of other vinyl monomers copolymerizable with the above components (a) to (d) is 40 to 170 mgKOH/g, and the acid value is 10 to 80.
mgKOH/g, weight average molecular weight 10000-100
000 and 60-90% by weight of a copolymer salt obtained by partially or completely neutralizing the acrylic copolymer (A) with a base.
, the alkoxyalkylated melamine resin (B) is 10-40% by weight based on the acrylic copolymer (A).
A thermosetting coating composition containing an aqueous solvent as an essential component.