JPH0827411A - Coating composition and coating film forming method - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the storage stability of paint in a demelamine curing system for acid rain resistance. A curable resin composition 1 containing a polymer having a carboxyl group and a carboxylic acid (half) ester group / a polymer having a hydroxyl group and an epoxy group, and a polymer having a specific hydroxyl group and a carboxyl group as required.
A coating composition containing 0.1 to 6 parts by weight of oxyacid with respect to 00 parts by weight, and a method for forming a coating film using this coating composition. [Effect] By mixing an oxyacid, the storage stability of the paint can be improved without impairing the basic performance as a paint for acid rain resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition having good storage stability, which can be suitably used as a top coating material for automobiles, a coating material for coil coating and the like, and a coating film forming method using the same.

[0002]

2. Description of the Related Art It is common to use a combination of a hydroxyl group-containing polymer and a melamine resin curing agent in a binder used as a top coating for automobiles. However, a cured coating film obtained by using such a melamine resin as a curing agent generally has poor acid resistance. Therefore, such a coating film is particularly likely to be deteriorated by acid rain, which has been a problem in recent years, and causes a defect in appearance.

It is considered that the coating film obtained by using a melamine resin as a curing agent is inferior in acid resistance due to the triazine nucleus in the melamine resin. Therefore, as long as the melamine resin is used as a curing agent, the drawback of poor acid resistance cannot be solved.

In order to solve such a drawback, the inventors of the present invention have disclosed JP-A-2-45577 and JP-A-3-4577.
In 287650, a novel coating composition that does not use a melamine resin has been proposed. Similar coating compositions are disclosed in US Pat. Nos. 2,977,334 (Zopf et al.), 3399109 (Zimmerman et al.) And 3,528,935 (Marion).
Et al.). Such a coating composition has good acid resistance because it has an ester bond formed by reacting an acid group and an epoxy group as a cross-linking point, and also has sufficient weather resistance as a top coating film for automobiles. Storage stability, especially above 50 ° C, was insufficient

[0005]

DISCLOSURE OF THE INVENTION The present invention is to solve the above-mentioned problems of the prior art. The object of the present invention is to provide good storage stability and high cross-linking density so that the weather resistance, especially It is an object of the present invention to provide a coating composition capable of providing a coating film having excellent resistance to acid rain and also having excellent elongation and scratch resistance, and a method for forming a coating film using the same.

[0006]

According to the present invention, [I]
A curable resin composition containing the following (A) and (B) and optionally the following (C) and / or (D), and (A) (i) (1) acid anhydride group-containing ethylenic An acid anhydride group-containing polymer obtained by copolymerizing 15 to 40% by weight of a saturated monomer and (2) 60 to 85% by weight of another copolymerizable ethylenically unsaturated monomer; and (ii) 1.
A carboxyl group and a carboxylic acid ester obtained by reacting a monoalcohol containing 12 to 12 carbon atoms in an amount such that the acid anhydride group / hydroxyl group molar ratio is 1/10 to 1/1. Polymers having groups 20 to 6
0% by weight (% by weight of the polymer is based on the total weight of the solid content of the resin composition, the same applies hereinafter): and (B) (i) Formula (I)

[0007]

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[Wherein, R is a hydrogen atom or a methyl group, X is a linear or branched alkyl or hydroxyalkyl, m is an integer of 2 to 8, n is an integer of 3 to 7, and q is Is an integer of 0 to 4] 5 to 60% by weight of a hydroxyl group-containing ethylenically unsaturated monomer having a structure represented by
(Ii) Epoxy group-containing ethylenically unsaturated monomer 10 to
60% by weight, and optionally 30 to 60% by weight of a polymer containing a hydroxyl group and an epoxy group, obtained by copolymerizing (iii) another copolymerizable ethylenically unsaturated monomer of 0 to 85% by weight. % (However, when components (C) and (D) are not included, the ratio of 50 to 250 parts by weight of component (B) relative to 100 parts by weight of solid content of component (A))
And 5 to 50% by weight of a polymer having a hydroxyl group and a carboxyl group of the following (C) and / or (D) as necessary: (C) (i) the hydroxyl group-containing ethylenically unsaturated monomer and acid anhydride group-containing compound And hydroxyl group / acid anhydride group molar ratio of 1 / 0.9 to 1 / 0.5 are mixed and reacted to obtain a carboxyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing ethylene. 20 to 100% by weight of a monomer mixture with a polyunsaturated monomer, and optionally (ii) a copolymerizable ethylenically unsaturated monomer
Polymer having a hydroxyl group and a carboxyl group, which is obtained by copolymerizing 80 to 80% by weight of (D) (i) formula (II)

[0009]

[Chemical 4]

[Wherein R ¹ is a methyl, phenyl or phenylethyl group, and R ² and R ³ are independently methyl, phenyl, phenylethyl, 3-hydroxypropyl or 3- (hydroxyethoxy) propyl. R ⁴ is methyl, 3-hydroxypropyl or 3-
Is a (hydroxyethoxy) propyl group, R ⁵ is a methyl, phenyl, phenylethyl or isobutyl group, l is an integer of 1-20, m is an integer of 2-4, and n is 0-2. An integer], at least one selected from the group consisting of compounds having a structure
A hydroxyl group-containing silicone polymer having an average of 3 to 12 hydroxyl groups in the molecule, and (ii) an acid anhydride group-containing compound, wherein the molar ratio of hydroxyl group / acid anhydride group is 1 / 1.0 to 1 /
A silicone polymer having a hydroxyl group and a carboxyl group obtained by carrying out a half-esterification reaction in an amount of 0.2 [II] oxyacid is mixed with 100 parts by weight of a solid content of the curable resin composition (I). A coating composition comprising 0.1 to 6 parts by weight of solids of acid (II) is provided.

According to the present invention, there is also provided (i) a step of forming a base coating film by using a water-based or solvent-based base coating material on an undercoated or undercoated and intermediate coated substrate; (ii) curing the base coating film The step of applying the coating composition as described above to form a clear coating film without doing so; and (iii) a step of curing the base coating film and the clear coating film by heating. A method for forming a coating film is provided, which is performed in this order.

The specific construction of the present invention and its effects will be described below. [I] (A) Polymer Having Carboxyl Group and Carboxylic Acid Ester Group (Polymer A) The polymer (A) having a carboxyl group and a carboxylic acid ester group used in the curable resin composition of the present invention contains an acid anhydride group. Polymer (a) (i) and monoalcohol (a)
A half-ester group-containing polymer obtained by reacting with (ii).

The acid anhydride group-containing polymer (a) (i) is an acid anhydride group-containing ethylenically unsaturated monomer (a) (i) (1).
15-40% by weight, preferably 15-30% by weight and other copolymerizable ethylenically unsaturated monomer (a) (i) (2)
It is obtained by copolymerizing 60 to 85% by weight, preferably 70 to 85% by weight. When the amount of the acid anhydride group-containing ethylenically unsaturated monomer (a) (i) (1) is less than 15% by weight, the curability is insufficient, and when it exceeds 40% by weight, the resulting coating film becomes too hard and brittle. It is not preferable because it lacks the property.

Specific examples of the acid anhydride group-containing ethylenically unsaturated monomer (a) (i) (1) include itaconic anhydride, maleic anhydride and citraconic anhydride. Other copolymerizable ethylenically unsaturated monomers (a) (i) (2)
Is not particularly limited as long as it does not adversely affect the acid anhydride group, and has 3 to 10 carbon atoms having one ethylenically unsaturated bond.
It is preferable that the number of monomers is 15, especially 2 to 12.

It is also possible to mix two or more kinds of ethylenically unsaturated monomers and use them as other copolymerizable ethylenically unsaturated monomers (a) (i) (2). This is because it is effective in improving the compatibility between the resins.
Specific examples of such a monomer that can be suitably used include styrene derivatives such as styrene, α-methylstyrene, and pt-butylstyrene as ethylenically unsaturated monomers,
(Meth) acrylic acid ester (for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid-n, i, and t-butyl, (meth) acrylic acid) 2-ethylhexyl and lauryl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, etc., VeoVa-9 and VeoVa- manufactured by Shell Co.
10 etc. are mentioned. It is also possible to use monomers having a carboxyl group such as acrylic acid and methacrylic acid. If styrene or a derivative thereof is used as the other copolymerizable monomer, it is particularly preferably used in an amount of 5 to 40% by weight.

The above-mentioned copolymerization is carried out by a known method such as solution polymerization such as radical polymerization, and can be carried out, for example, at a polymerization temperature of 100 to 150 ° C. and a polymerization time of 3 to 8 hours. As the initiator, an azo type or peroxide type initiator is preferably used. Other additives such as chain transfer agents can also be used. The number average molecular weight of the obtained polymer is 1500-8000, especially 2000-50.
It is preferably 00. When the number average molecular weight exceeds 8,000, the polymer viscosity becomes high, and it becomes difficult to prepare a coating composition having a high solid content. If the number average molecular weight is less than 1500, the curability of the curable resin composition will be insufficient. The resulting polymer has an average of at least 2 and preferably 2 to 15 acid anhydride groups per molecule. If the number of acid anhydride groups contained in one molecule is less than 2, the curability of the curable resin composition will be insufficient. If it exceeds 15, it becomes too hard and brittle, and the weather resistance is insufficient.

Then, the obtained polymer is mixed in a molar ratio of acid anhydride group / hydroxyl group of 1/10 to 1/1, preferably 1 /.
8 to 1 / 1.1, more preferably 1 / 1.5 to 1/1.
A polymer (A) having a carboxyl group and a carboxylic acid ester group is prepared by reacting with the monoalcohol (a) (ii) in an amount of 3. This ratio is 1
When it exceeds / 10, the excess alcohol is too much and causes cracking during curing. When it is less than 1/1, unreacted anhydride groups remain and storage stability deteriorates.

The monoalcohol (a) (i) usable in the present invention
i) is a low molecular weight compound having 1 to 12, preferably 1 to 8 carbon atoms. This is because the alcohol volatilizes when heated and is good for regenerating the acid anhydride group.
In the present invention, the monoalcohol that can be preferably used includes
Examples include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, methyl cellosolve, ethyl cellosolve, dimethylaminoethanol, diethylaminoethanol, acetol, allyl alcohol and propargyl alcohol. Particularly preferred are acetol, allyl alcohol, propargyl alcohol and methanol.

[I] (B) Polymer Having Hydroxyl Group and Epoxy Group (Polymer B) The polymer (B) having hydroxyl group and epoxy group used in the resin composition of the present invention preferably has an epoxy group on average in one molecule. Has from 2 to 10, more preferably from 3 to 8, and has an average of preferably from 2 to 12, and more preferably from 4 to 10 hydroxyl groups. The epoxy equivalent is preferably 100 to 800, more preferably 200 to 600, and the hydroxy equivalent is preferably 200 to 1200, more preferably 400 to 1000. When the epoxy equivalent is larger than the above upper limit, the curability of the curable resin composition becomes insufficient. On the other hand, if it is less than the above lower limit, the coating becomes too hard and the coating becomes brittle, which is not preferable. When the hydroxy equivalent weight is less than 200, the water resistance of the cured coating film is insufficient,
If it exceeds 1200, the curability is not sufficient, which is not preferable.

Such a polymer (B) has, for example, the formula (I):

[0021]

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[Wherein, R is a hydrogen atom or a methyl group, X is a linear or branched alkyl or hydroxyalkyl, m is an integer of 2 to 8, n is an integer of 3 to 7, and q is Is an integer of 0 to 4] and a hydroxyl group-containing ethylenically unsaturated monomer (b) (i) having a structure of 5 to 6
0% by weight, preferably 15 to 30% by weight, epoxy group-containing ethylenically unsaturated monomer (b) (ii) 10 to 60% by weight, preferably 15 to 50% by weight, and optionally other copolymerizable Ethylenically unsaturated monomer (b) (iii)
It can be obtained by copolymerizing 0 to 85% by weight, preferably 10 to 60% by weight. If the hydroxyl group-containing ethylenically unsaturated monomer is less than 5% by weight, curability is insufficient, and if it exceeds 60% by weight, compatibility is insufficient and the reaction does not proceed sufficiently, which is not preferable. If the epoxy group-containing ethylenically unsaturated monomer is less than 10% by weight, curability is insufficient, and if it exceeds 60% by weight, it becomes too hard and weather resistance becomes insufficient, which is not preferable.

If the hydroxyl group-containing alkyl chain of the hydroxyl group-containing ethylenically unsaturated monomer (b) (i) which can be used for preparing the polymer (B) having a hydroxyl group and an epoxy group is too short, Since the flexibility in the vicinity of the crosslinking points is lost, it becomes too hard, and when it is too long, the molecular weight between the crosslinking points tends to be too large. Therefore, the hydroxyl group-containing alkyl chain preferably has 4 to 20 carbon atoms, and more preferably 4 to 10 carbon atoms. Specifically, with 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and their reaction products with ε-caprolactone, and with ε-caprolactone of 2-hydroxyethyl (meth) acrylate. Compounds such as the reaction products of Such compounds are commercially available, for example, "Plaxel FM1" and "Plaxel FA manufactured by Daicel Chemical Industries, Ltd."
1 ”and the like. Or, such a compound is
(Meth) acrylic acid and large excess (eg 1.5 times (mol))
Or more) diol (for example, 1,4-butanediol,
It can be prepared by esterifying 1,6-hexanediol).

Examples of the monomer (b) (ii) include:
Examples thereof include glycidyl (meth) acrylate and 3,4-epoxycyclohexanylmethyl (meth) acrylate. Examples of the other monomer (c) (iii) include "other copolymerizable ethylenically unsaturated monomer (a) (i) (2)" for preparing the acid anhydride group-containing polymer (a) (i). "
Examples of the monomer include the above-mentioned monomers.

The above-mentioned copolymerization is carried out by a known method such as solution polymerization such as radical polymerization, and can be carried out, for example, at a polymerization temperature of 100 to 150 ° C. and a polymerization time of 3 to 8 hours. As the initiator, peroxide type and azo type initiators are preferably used. Further, the radical polymerization initiator is preferably used in an amount of 0.5 to 15% by weight based on all monomers. Other additives such as chain transfer agents may be added to the above-mentioned monomer composition. The resulting polymer has a number average molecular weight of 500 to 8000, especially 150.
It is preferably 0 to 5000.

According to the present invention, the following polymers (C) and / or (D) can be used if necessary. [I] (C) Polymer Having Hydroxyl Group and Carboxyl Group (Polymer C) The polymer (C) having a hydroxyl group and a carboxyl group that can be used in the curable coating composition of the present invention is at least two types of ethylenic monomers. It is a copolymer of saturated monomers. (C) (i) A mixture of a carboxyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing ethylenically unsaturated monomer has the formula (I) ′

[0027]

[Chemical 6]

[Wherein, R is a hydrogen atom or a methyl group, X is a linear or branched alkyl or hydroxyalkyl, m is an integer of 2 to 8, preferably 2 to 6, and n is 3 to 7] , Preferably an integer of 3 to 5, q is 0 to 4,
Preferably, it is an integer of 0 to 2] A carboxyl group-containing ethylenically unsaturated monomer obtained by half-esterifying a hydroxyl group-containing ethylenically unsaturated monomer having a structure represented by the formula and an acid anhydride group-containing compound. is there. This monomer is used for introducing a carboxyl group in the polymer (C) having a hydroxyl group and a carboxyl group used in the present invention.

The hydroxyl group-containing alkyl chain of the hydroxyl group-containing ethylenically unsaturated monomer that can be used in the present invention becomes too hard because the flexibility in the vicinity of the crosslinking point is lost if the chain length is too short, and the crosslinking point becomes too long if it is too long. The intermolecular weight becomes too large, which is not preferable. Therefore, the hydroxyl group-containing alkyl chain preferably has 4 to 20 carbon atoms, and more preferably 4 to 10 carbon atoms. Specifically, the compounds and preparation methods described above as the polymer (b) (i) can be used.

The acid anhydride group-containing compound that can be used in the present invention is particularly limited as long as it is a compound having a carboxy functionality by reacting with a hydroxyl group under ordinary reaction conditions such as room temperature to 120 ° C. and normal pressure. Not done. Here, it is preferable to use an acid anhydride group-containing compound having a cyclic (unsaturated or saturated) group having 8 to 12 carbon atoms, particularly 8 to 10 carbon atoms, because the compatibility of the resin is good.
Specific examples of preferable acid anhydrides include hexahydrophthalic anhydride, phthalic anhydride, 4-methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride and trimellitic anhydride.

The half-esterification reaction between the hydroxyl group-containing ethylenically unsaturated monomer and the acid anhydride group-containing compound can be carried out according to a conventional method, for example, at a temperature of room temperature to 120 ° C. At this time, it is preferable to use the hydroxyl group-containing ethylenically unsaturated monomer in an excessive amount in order to prevent the unreacted acid anhydride group from remaining.

The preferred monomer (c) (ii) as the copolymerizable ethylenically unsaturated monomer (c) (ii) has 3 to 15 carbon atoms, especially 2 having one ethylenically unsaturated bond.
~ 12 monomers. Furthermore, a hydroxyl group-containing ethylenically unsaturated monomer and a carboxyl group-containing ethylenically unsaturated monomer may be used, and in this case, a hydroxyl group and a carboxyl group can be further introduced into the polymer (c). It is preferable that the hydroxyl group contained in the second monomer is a primary hydroxyl group since the reactivity becomes good after being made into a coating.

It is also possible to use a mixture of two or more kinds of the above-mentioned monomers. This is because it is effective in improving the compatibility between the resins. Specific examples of such a monomer that can be suitably used include styrene, α-methylstyrene and p as the ethylenically unsaturated monomer.
-T-butyl styrene, (meth) acrylic acid ester (for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid -n, i, and t-butyl) , 2-ethylhexyl (meth) acrylate and lauryl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, etc., VeoVa- manufactured by Shell Co.
9 and VeoVa-10 and the like, and as the hydroxyl group-containing ethylenically unsaturated monomer, (meth) acrylic acid 2-
Examples include hydroxyethyl and 4-hydroxybutyl (meth) acrylate. Preferably, the hydroxyl group-containing ethylenically unsaturated monomer represented by the formula [I] may be used. Note that (meth) acrylic acid and itaconic acid can be included as the acid monomer.

Polymerization of a monomer mixture (c) (i) of a carboxyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing ethylenically unsaturated monomer with a copolymerizable ethylenically unsaturated monomer (c) (ii) is also possible. It can be carried out by usual solution polymerization. Polymerization is preferably carried out using an azo or peroxide initiator at a polymerization temperature of 100 to 150 ° C. and a polymerization time of 3 to 8 hours. At that time, a monomer mixture (c) of a carboxyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing ethylenically unsaturated monomer
(i) and the other monomer (c) (ii) are 20 to 100
%, Preferably 40-80% by weight / 0-80% by weight, preferably 20-60% by weight.

If the amount of the monomer mixture (c) (i) of the carboxyl group-containing ethylenically unsaturated monomer and the hydroxyl group-containing ethylenically unsaturated monomer is lower than 20% by weight, the curability becomes insufficient, which is not preferable. Even if the amount of the monomer (c) (ii) exceeds 80% by weight, the amount of the functional group becomes too low and the curability may be insufficient, which is not preferable.

Each of the above-mentioned monomers and radical polymerization initiator (any polymerization initiator usually used in radical polymerization may be used, and examples thereof include t-butylperoxy 2-ethylhexanoate and dimethyl 2,2'-azobisisobutyi. The polymer (C) having a hydroxyl group and a carboxyl group can be obtained by radically polymerizing a monomer composition containing a monomer (eg, rate, etc.).

In the polymerization, a monomer mixture of a carboxyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing ethylenically unsaturated monomer, and a copolymerizable ethylenically unsaturated monomer may be independently mixed in predetermined amounts. However, it is also possible to use the hydroxyl group-containing ethylenically unsaturated monomer represented by the formula [I] in an excessive amount in the above-mentioned half esterification step.

A hydroxyl group-containing ethylenically unsaturated monomer,
In addition to the amount necessary for half-esterification, the amount necessary for copolymerization is added in an excess amount to half-esterify with the acid anhydride group-containing compound to give a carboxyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing ethylenic unsaturated monomer. A monomer mixture with saturated monomers can be obtained. In this case, the hydroxyl group-containing ethylenically unsaturated monomer and the acid anhydride group-containing compound are generally used in a molar ratio of hydroxyl group / acid anhydride group of 1 / 0.9 to 1 / 0.5, particularly 1/0. 8-1 /
It is preferable to mix and react in an amount of 0.5. If this molar ratio is less than 1 / 0.9, it takes time to half-esterify and the monomer may gel,
On the other hand, if the molar ratio exceeds 1 / 0.5, the amount of carboxyl groups becomes too small and the curability becomes insufficient, which is not preferable.

The resulting monomer mixture (c) (i) of a carboxyl group-containing ethylenically unsaturated monomer and a hydroxyl group-containing ethylenically unsaturated monomer is copolymerized by the same method as described above, or if necessary, The polymer (C) having a hydroxyl group and a carboxyl group of the present invention can be obtained by further copolymerizing with the ethylenically unsaturated monomer (c) (ii). When the polymerization is carried out in this way, generally, the monomer mixture (c) (i) 20-1
00% by weight, preferably 40 to 80% by weight, and 0 to 80% by weight, preferably 20 to 60% by weight, of the ethylenically unsaturated monomer (c) (ii) are used.

When the amount of the monomer mixture (c) (i) is less than 20% by weight, the curability is insufficient, which is not preferable.

Thus, the polymer (C) having a hydroxyl group and a carboxyl group, which can be used in the coating composition of the present invention, is obtained. This polymer is 1500-2
0000, especially 2000-5000 number average molecular weight Mn
It is preferable to have If the number average molecular weight is less than 1500, the number of functional groups per molecule may be small and the curability may be insufficient. On the contrary, if it exceeds 20,000, the compatibility with other resins may be deteriorated. The molecular weight of the polymer used in the present invention is determined by the GPC method. The polymer is 25 to 250 in terms of solid content.
mgKOH / g, especially 30-200 mgKOH / g hydroxyl value and 50-200 mgKOH / g, especially 70-180 mgKOH / g
And an acid value of. Hydroxyl value is 25 mgK
If it is less than OH / g, the curability tends to deteriorate, and conversely 25
If it exceeds 0 mgKOH / g, the compatibility tends to deteriorate, which is not preferable. If the acid value is less than 50 mgKOH / g, the curability will deteriorate, and if it exceeds 200 mgKOH / g, the water resistance will tend to deteriorate due to the unreacted acid, which is not preferable.

[I] (D) Silicone Polymer Having Hydroxyl Group and Carboxyl Group (Polymer D) The silicone polymer (D) having a hydroxyl group and a carboxyl group, which is a component of the curable resin composition of the present invention, is a hydroxyl group-containing silicone. It can be obtained by half-esterifying the polymer (d) (i) and the acid anhydride group-containing compound (d) (ii).

The method for producing the hydroxyl group-containing silicone polymer (d) (i) which can be used in the present invention is 199.
Summary of 0th Organosilicon Materials Chemistry Symposium, 29th
It is described on page 30. Several of these are commercially available, for example, the Shin-Etsu Silicone KR shown in the following formula.
-2001 and NVC-Silicone series manufactured by Unicar Japan Ltd. can be mentioned.

[0044]

[Chemical 7]

This hydroxyl group-containing silicone polymer (d)
It is preferable that (i) has an average of 3 to 12 hydroxyl groups in one molecule. Hydroxyl group-containing silicone polymer (d)
(i) When the average number of hydroxyl groups contained in one molecule is less than 3, curability becomes insufficient, and when it exceeds 12, the viscosity becomes high and the nonvolatile content becomes low, which is not preferable.

The acid anhydride group-containing compound (d) (ii) which can be used in the present invention has a carboxy functional group by reaction with a hydroxyl group under ordinary reaction conditions such as room temperature to 120 ° C. and normal pressure. The compound provided is not particularly limited. In the present invention, an acid anhydride group-containing compound having a cyclic (unsaturated or saturated) group having 8 to 12 carbon atoms is preferable because the resin has good compatibility. Specific examples of preferable acid anhydride group-containing compound (d) (ii) include hexahydrophthalic anhydride, phthalic anhydride,
4-Methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride and the like can be mentioned.

Hydroxyl group-containing silicone polymer (d) (i)
The half-esterification reaction between the acid anhydride group-containing compound (d) (ii) and the acid anhydride group-containing compound is carried out according to a conventional method, for example, at room temperature to 120 ° C. for 30 minutes to 8 hours. When the reaction is carried out for a long time under violent conditions exceeding 120 ° C., a polyesterification reaction occurs to tend to produce a high molecular weight silicone polyester, and such a silicone polyester has a small number of functional groups and has a high viscosity. Therefore, it is not preferable for use in the present invention. The reaction ratio of the half-esterification reaction is 1 / 1.0 to 1 for the hydroxyl group and the acid anhydride group.
It is preferable to carry out in an amount of /0.2. If this ratio exceeds 1 / 0.2, the water resistance becomes poor, and 1 /
If it is less than 1.0, an excessive amount of acid anhydride remains in the system, causing a side reaction when used in a coating composition, which is not preferable.

The silicone polymer having a hydroxyl group and a carboxyl group obtained in this manner is 500 to 60.
00, especially a number average molecular weight M in the range of 1000 to 4500
It is preferred to have n. This number average molecular weight is 600
If it exceeds 0, the viscosity may increase and the nonvolatile content may decrease, and if it is less than 500, curability may be insufficient, which is not preferable. The molecular weight of the polymer used in the present invention is determined by the GPC method. The silicone polymer having a hydroxyl group and a carboxyl group preferably has an acid value of 20 to 180, particularly 35 to 150, and a hydroxyl value of 2 to 120, especially 10 to 80. In particular, if the acid value is less than 20, the curability tends to be insufficient, and conversely, if it exceeds 180, the nonvolatile content tends to decrease, which is not preferable.

The curable resin composition used in the present invention is blended in the polymer (A) and the carboxyl group and the polymer (B) contained in the polymer (C) and / or (D) optionally added. The molar ratio with the contained epoxy group is 1 / 1.2-1 to 0.6, preferably 1 / 1.0-1.
/0.8 and the carboxyl group or carboxylic acid ester group contained in the polymer (A) (usually, the carboxyl group and the carboxylic acid ester group in the polymer (A) are present in equimolar amounts) and the polymer. It is preferable to carry out in an amount such that the molar ratio with the hydroxyl group contained in (B) and (C) and / or (D) added as necessary is 1 / 1.5 to 1 / 0.5.

The ratio of the carboxyl groups contained in the polymer (A) and optionally the polymers (C) and / or (D) to the epoxy groups contained in the polymer (B) is 1 / 0.6. If it exceeds the range, the curability of the obtained resin composition tends to decrease, and if it is less than 1 / 1.2, the coating film tends to yellow, which is not preferable. The molar ratio of the carboxyl group or carboxylic acid ester group contained in the polymer (A) to the hydroxyl group contained in the polymer (B) and optionally the polymers (C) and (D) is 1 /.
If it exceeds 0.5, the curability of the obtained resin composition will be deteriorated, and if it is less than 1 / 1.5, hydroxyl groups tend to be excessive and water resistance tends to be deteriorated, such being undesirable.

The above-mentioned compounding amount can be calculated from the hydroxyl value, acid value and epoxy equivalent of each polymer by a calculation method well known to those skilled in the art. In the coating composition of the present invention, when the polymer (C) and / or (D) is not added, 50 to 250 solid parts by weight of the polymer (B), preferably 100 to 100 parts by weight of the solid content of the polymer (A), Is mixed in an amount of 80 to 150 parts by weight of solid content. If the content of (B) is less than 50 parts by weight of solid content, sufficient curing will not be carried out, and the water resistance and weather resistance of the cured coating film will decrease, which is not preferable. When the polymer (C) and / or (D) is added to the polymers (A) and (B), the polymer (C) and / or (D) having a hydroxyl group and a carboxyl group is 5 to 50% by weight, preferably 5 to 40% by weight of a polymer (A) having a carboxyl group and a carboxylic acid ester group, 20 to 60
It can be obtained by blending the polymer (B) containing a hydroxyl group and an epoxy group in an amount of 30 to 60% by weight, preferably 35 to 55% by weight, and preferably 25 to 55% by weight. If the amount of the polymer (C) and / or (D) is more than 50% by weight, the coating film becomes too soft and the acid resistance is lowered, and if it is less than 5%, the scratch resistance tends to be lowered. If the content of the polymer (A) is less than 20% by weight, the acid resistance is lowered, and if it exceeds 60% by weight, the coating film becomes too hard, which is not preferable. Since the polymer (B) is blended in an amount suitable for the total amount of acid groups contained in the system, if the amount is less than the amount corresponding to the acid groups, the curability decreases, and if it is too large, the yellowing resistance deteriorates, which is not preferable. .

The curing mechanism of the coating composition of the present invention thus obtained is as follows. First, the carboxyl group in the polymer (A) reacts with the carboxylic acid ester group to cause acid anhydride in the polymer (A). A physical group is formed and a free monoalcohol is formed. The produced monoalcohol is removed from the system by evaporation. The acid anhydride group formed in the polymer (A) reacts with the hydroxyl group contained in the polymer (B) and optionally the polymer (C) and / or (D) to form a crosslinking point, The acid group is formed again. The acid group and the carboxyl group contained in the polymer (C) and / or (D) optionally added are the epoxy group contained in the polymer (B) and the acid contained in the polymer (A). A cross-linking point is formed by reacting. In this way, the curing proceeds by the mutual reaction of the three types of polymers.

Since the polymers react with each other by the mechanism described above, a high crosslink density can be obtained according to the present invention. Further, according to the present invention, since the hydroxyl group and the carboxyl group of the polymer (C) component are separated from the main chain, the degree of freedom of movement in the vicinity of the cross-linking point is high, so that the elongation rate is high and the abrasion resistance is low. It is presumed that it exerts its performance. Further, the polymer (D) component also improves the scratch resistance.

[II] Oxyacid The oxyacid used in the present invention is preferably a hydroxy acid, which is a compound having a carboxyl group and an alcoholic hydroxyl group in one molecule as shown below, and specific examples include monobasic oxy acid and dioxy acid. Examples of the monobasic oxyacid include basic oxyacids, and examples of the monobasic oxyacid include glycolic acid, lactic acid, hydroacrylic acid and β-oxy acid. Glycolic acid and lactic acid are preferably used, and lactic acid is particularly preferably used. On the other hand, the dibasic acid can be, for example, tartronic acid, malic acid, tartaric acid, citric acid, etc. Among these, malic acid, lactic acid, and glycolic acid are preferably used, and malic acid is particularly preferable. . The above oxy acids can be used alone or as an arbitrary mixture.

The composition of the coating composition according to the present invention comprises component [II] based on 100 parts by weight of curable resin component [I] solid content.
0.1 to 6 solids by weight, preferably 0.2 to 4 solids by weight, more preferably 0.5 to 3 solids by weight. If the compounding amount of the component [II] is less than 0.1 parts by weight solid content, the improvement of the storage stability is insufficient, while if it exceeds 6 parts by weight moisture resistance of the coating film cannot be obtained and blister occurs. Is not preferred. According to the present invention, the storage stability of the obtained coating composition is significantly improved by adding an oxyacid to the coating composition.

Furthermore, in the acid-epoxy curing method described above, the hydroxyl group of the oxyacid blocks the epoxy group, improving the storage stability of the resulting coating composition. During baking after coating, the hydroxyl group of oxyacid reacts with the epoxy group and the acid anhydride group, and free oxyacid does not remain in the coating film, so that the coating film performance after baking is not adversely affected.

Additives In addition to the polymer components (A) and (B) and the polymers (C) and / or (D) optionally blended,
The resin component (I) of the coating composition of the present invention may be mixed with a curing catalyst usually used in the esterification reaction of an acid such as a quaternary ammonium salt with an epoxy. Specific examples of other catalysts that can be used in the resin component (I) of the coating composition of the present invention include, for example, benzyltriethylammonium chloride or bromide, tetrabutylammonium chloride or bromide, salicylate or glycolate, and paratoluene sulfonate. To be You may mix and use these catalysts. The amount of the catalyst blended is not particularly limited, but generally 0.1 to 2.0% by weight based on the solid content of the curable resin composition is preferable. Further, as described in JP-A-2-151651 and JP-A-2-279713, tin compounds may be used in combination therewith. Examples of such tin-based catalysts include dimethyltin bis (methylmalate),
Examples thereof include dimethyltin bis (ethyl maleate), dimethyltin bis (butyl maleate), dibutyltin bis (butyl maleate) and the like. The weight ratio of the curing catalyst to the tin compound is preferably 1/4 to 1 / 0.2.

In the present invention, a melamine-formaldehyde resin and / or a blocked isocyanate may be added to the curable resin component [I] in order to increase the crosslink density and improve the water resistance. Further, in order to improve the weather resistance of the coating film, an ultraviolet absorber, a hindered amine light stabilizer, an antioxidant and the like may be added. Further, crosslinked resin particles as a rheology control agent and a surface conditioner for adjusting the appearance may be added. Furthermore, alcohol-based solvents (for example, methanol, ethanol, propanol, butanol, etc.), hydrocarbon-based solvents, ester-based solvents and the like can also be used as diluents for viscosity adjustment and the like.

Further, since the resin compounded in the coating composition of the present invention has an acid group as a functional group, it can be neutralized with an amine to give an aqueous resin composition containing water as a medium.

Coating system The coating composition of the present invention can be suitably used as a clear coating composition. In this case, as the base coating material, an aqueous coating material containing a bright pigment and / or a coloring pigment and an organic solvent type coating material containing a bright pigment and / or a coloring pigment are preferably used. Upon coating, the base coating surface is not cured, but a clear coating is applied to the surface of the base coating with the coating composition of the present invention, and then both coating films are cured.
The coat 1 bake curing method is preferably used.

However, when an aqueous paint is used,
In order to obtain a good finished coating film, the base coat should be preheated at a temperature of 60 to 100 ° C. for 2 to 2 times before applying the clear paint.
It is preferable to heat for 10 minutes. As base paints, US Pat. Nos. 5,151,125 and 5,18
Those specifically described in No. 3,504 can be used. Particularly, (a) amide group-containing ethylenic monomer 5 to 40 described in US Pat. No. 5,183,504.
% By weight, 3 to 15% by weight of acidic group-containing ethylenic monomer, 10 to 40% by weight of hydroxyl group-containing ethylenic monomer and the number average molecular weight of 6,000 to 50 obtained by copolymerizing the remaining amount of other ethylenic monomer. Film-forming polymer obtained by neutralizing at least a part of the acidic groups of the copolymer of 100,000 (solid content), and (b) a terminal hydroxyl group having a molecular weight of 100 to 5,
000 diol compounds, diisocyanate compounds and hydrophilic group-containing oligomers obtained by reacting a compound having at least one active hydrogen in a molecule and having a hydrophilic group under an isocyanate-rich condition / Or 5 to 90% by weight of urethane-containing water dispersion obtained by dispersing in an aqueous medium containing a secondary polyamine
An aqueous coating composition containing (solid content) is most suitable in terms of finish, appearance and performance.

Production Method The production method of the coating composition of the present invention is not particularly limited, and any method known to those skilled in the art can be used. For example, in the case of an enamel coating, a desired coating composition can be obtained by kneading and dispersing a mixture of pigments and the like using a kneader or a roll according to a conventional method. The solid content of the coating composition according to the present invention is 30-
It is preferably 70% by weight and 10 to 50% by weight at the time of coating.

Coating Method The coating composition of the present invention is applied by spray coating, brush coating,
It can be applied by any conventional general-purpose coating method such as dip coating, roll coating, or flow coating. The substrate as the coating base may be undercoated or undercoated and intermediate coated, if necessary. Known undercoat paints and intermediate paints can be used.

The coating composition of the present invention may advantageously be applied to any substrate, such as wood, metal, glass, cloth, plastics, foams and the like, especially plastic and metal surfaces such as steel, aluminum and alloys thereof. You can

The dry film thickness of the coating film of the coating composition of the present invention can be varied over a wide range depending on the desired use, but in many cases, 20 to 80 μm is useful.

According to the coating method of the present invention, after coating the substrate, the coating film is cured. Curing can give a cured coating film having a high degree of crosslinking at a temperature of 100 to 180 ° C, preferably 120 ° C to 160 ° C. The curing time varies depending on the curing temperature and the like, but generally, it is suitable to cure at a temperature of 120 ° C to 160 ° C for 10 to 30 minutes.

[0067]

EXAMPLES The present invention will be described in more detail below with reference to Examples, but it goes without saying that the scope of the present invention is not limited to these Examples. In the following examples, “parts” means parts by weight unless otherwise specified.

Preparation Examples 1 to 30 Preparation Examples 1 to 10 describe the preparation of the polymer (A) having a carboxyl group and a carboxylic acid ester group used in the curable resin composition of the present invention. In addition, Preparation Examples 1 to 5 are preparation of acrylic polymers (A-i) to (Av) having an acid anhydride group as a precursor thereof.

Preparation Example 1 80 parts of xylene was charged into a 1 liter reaction vessel equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube and a dropping funnel, the temperature was raised to 115 ° C., and 25 parts of styrene and acrylic acid n were added.
-Butyl 21 parts, n-butyl methacrylate 95 parts, 2-ethylhexyl methacrylate 34 parts, itaconic anhydride 5
A monomer consisting of 0 part, 100 parts of propylene glycol monomethyl ether acetate and 10 parts of t-butylperoxy 2-ethylhexanoate, and an initiator solution were added dropwise over 3 hours, and stirring was continued for another 2 hours. %, An acrylic polymer (Ai) having an acid anhydride group having a number average molecular weight of 5,500 was obtained.

Preparation Examples 2 and 3 An acrylic polymer (A-ii) having an acid anhydride group was prepared in the same manner as in Preparation Example 1 except that the formulations shown in Table 1 below were used.
And (A-iii) were obtained.

Preparation Example 4 250 parts of xylene and 500 parts of Solvesso-100 (manufactured by Esso Co.) were charged to a 2 liter reaction vessel equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube and a dropping funnel, and 130 ° C. The temperature is raised to 215 parts of styrene, 225 parts of n-butyl acrylate and 115 parts of isobutyl methacrylate.
Part, 160 parts of itaconic anhydride, 250 parts of propylene glycol monomethyl ether acetate and 100 parts of t-butylperoxy-2-ethylhexanoate, and an initiator solution are added dropwise over 3 hours.
Hold at 30 ° C. for 30 minutes, add 15 parts xylene and 15 parts t-butylperoxy-2-ethylhexanoate dropwise over 30 minutes, continue stirring for an additional 1 hour, and remove 900 parts solvent under reduced pressure. Thus, an acid anhydride group-containing acrylic polymer (A-iv) having a nonvolatile content of 77% and a number average molecular weight of 2300 was obtained.

Preparation Example 5 215 parts of styrene, 2-ethylhexyl acrylate 85
Example 4 except that a monomer consisting of 100 parts by weight, 200 parts of isobutyl methacrylate and 215 parts of maleic anhydride was used.
In the same manner as described above, the nonvolatile content is 78% and the number average molecular weight is 20.
An acid anhydride group-containing acrylic polymer (Av) of No. 00 was obtained.

[0073]

[Table 1]

Preparation Examples 6 to 10 below describe the preparation of the polymer (A) having a carboxyl group and a carboxylic acid ester group.

Preparation Example 6 To 385 parts of the polymer (A-i) obtained in Preparation Example 1 was added 18.2 parts of methanol, and the mixture was reacted at 65 ° C. for 24 hours to have a carboxyl group and a carboxylic acid ester group. A polymer (AI) was obtained. The disappearance of absorption of an acid anhydride group (1785 cm ^-1 ) was confirmed by IR.

Preparation Examples 7 to 10 Polymers (A-II) to (AV) having a carboxyl group and a carboxylic acid ester group were prepared in the same manner as in Preparation Example 6 except that the formulations shown in Table 2 below were used. Got As a result of investigating the obtained polymer by IR, it was confirmed that the absorption of the acid anhydride group disappeared.

[0077]

[Table 2]

Preparation Examples 11-14 Preparation Examples 11-14 describe the preparation of the polymer (B) containing a hydroxyl group and an epoxy group used in the coating composition of the present invention.

Preparation Example 11 500 parts of butyl acetate were charged into a 2 liter reaction vessel equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube and a dropping funnel, and the temperature was raised to 125 ° C.

50 parts of styrene, 400 parts of glycidyl methacrylate, 350 parts of 4-hydroxybutyl acrylate, 200 parts of 2-ethylhexyl acrylate and 7 parts of t-butylperoxy 2-ethylhexanoate were added to the dropping funnel.
0 part of the monomer and the initiator solution were added dropwise over 3 hours. After the dropping is completed, the temperature is maintained at 125 ° C. for 30 minutes, and then t
A solution consisting of 10 parts of -butylperoxy 2-ethylhexanoate and 250 parts of xylene was added dropwise over 30 minutes. After the dropping is completed, the reaction is continued at 125 ° C for 2 hours,
A polymer (BI) having a non-volatile content of 59%, a number average molecular weight of 4,000, a hydroxy equivalent of 411, and an epoxy equivalent of 355 and having a hydroxyl group and an epoxy group was obtained.

Preparation Examples 12 to 14 A polymer having a hydroxyl group and an epoxy group (B-) was prepared in the same manner as in Preparation Example 11 except that the formulations shown in Table 3 below were used.
II) to (B-IV) were synthesized. Table 3 shows the characteristic values of the obtained polymer.

[0082]

[Table 3]

Preparation Examples 15 to 25 In Preparation Examples 15 to 25, the polymer (C) having a hydroxyl group and a carboxyl group used in the curable coating composition of the present invention.
The preparation of is explained.

In Preparation Examples 15 to 19, the carboxyl group-containing ethylenically unsaturated monomer (c-
The preparation of i) to (cv) will be described.

Preparation Example 15 Arcosolve PMA was placed in a 2 liter reaction vessel equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube and a dropping funnel.
(Kyowa Yuka Co., Ltd.) 360 parts solvent, 4-acrylic acid
Hydroxybutyl 777 parts, hexahydrophthalic anhydride 665 parts and hydroquinone monomethyl ether 0.4
8 parts were charged, the temperature was raised to 145 ° C., and the temperature was maintained for 20 minutes. Then, it cooled and taken out from the reaction container, and the carboxyl group-containing ethylenically unsaturated monomer (ci) was obtained.

Preparation Examples 16 to 19 Carboxyl group-containing ethylenically unsaturated monomers (c-ii) to (cv) were obtained in the same manner as in Preparation Example 15 except that the formulations shown in Table 4 below were used. .

[0087]

[Table 4]

Preparation Examples 20 to 25 explain the preparation of the polymer (C) having a hydroxyl group and a carboxyl group.

Preparation Example 20 A 3 liter reaction vessel equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube and a dropping funnel was charged with 300 parts of xylene and 200 parts of Arcosolve PMA solvent and heated to 130 ° C.
The temperature was raised to. Then, the carboxyl group-containing ethylenically unsaturated monomer (ci) 1300 obtained in Preparation Example 15
Parts of t-butylperoxy 2-ethylhexanoate 1
00 parts was added dropwise over 3 hours. After maintaining at 130 ° C. for 30 minutes, 30 parts of a mixed solution of 10 parts of t-butylperoxy 2-ethylhexanoate and 100 parts of xylene was added.
It dripped over minutes. After maintaining at 130 ° C. for 30 minutes, the mixture was cooled and taken out from the container to obtain a polymer C-I having a hydroxyl group and a carboxyl group. This polymer has a nonvolatile content of 54%, a number average molecular weight of 2000, an acid value of 168 mgKOH / g and a hydroxyl value of 42 mgKOH / g in terms of solid content.
It was a transparent liquid having.

Preparation Examples 21 to 25 Polymers (C-II) to (C-XI) having a hydroxyl group and a carboxyl group were obtained in the same manner as in Preparation Example 20 except that the formulations shown in Table 5 below were used. . The properties of these polymers are also shown in Table 5.

[0091]

[Table 5]

Preparation Examples 26 to 29 Preparation Examples 26 to 29 describe the preparation of the silicone polymer (D) having a hydroxyl group and a carboxyl group used in the coating composition of the present invention.

Preparation Example 26 140 parts of butyl acetate were placed in a 2 liter reaction vessel equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube and a dropping funnel.
formula

[0094]

Embedded image

KR manufactured by Shin-Etsu Silicone Co., Ltd.
1088 parts of -2001 and 370 parts of hexahydrophthalic anhydride were charged, the temperature was raised to 125 to 130 ° C, and the reaction was carried out for 2 hours. After confirming the disappearance of absorption of the acid anhydride group by IR analysis, 206 parts of butyl acetate was added to obtain a colorless and transparent varnish. The resulting silicone polymer having a hydroxyl group and a carboxyl group (hereinafter,
The polymer (designated as DI)) had a nonvolatile content of 80% and an acid value of 95 mgKOH / g (solid content).

Preparation Example 27 A colorless and transparent varnish-like product was obtained in the same manner as in Preparation Example 26 except that the formulations shown in Table 6 below were used. Table 6 shows the nonvolatile content and acid value of each of the obtained silicone polymers having a hydroxyl group and a carboxyl group (hereinafter, referred to as polymer (D-II)).

Preparation Example 28 Formula

[0098]

[Chemical 9]

[Wherein Me is a methyl group, Ph is a phenyl group, and A is a 3- (hydroxyethoxy) propyl group], and a silicone polymer having a structure shown in Table 6 below is used. A colorless and transparent varnish-like product was obtained in the same manner as in Preparation Example 26 except that the formulation shown below was used.
Table 6 shows the nonvolatile content and acid value of the obtained silicone polymer having a hydroxyl group and a carboxyl group (hereinafter referred to as polymer (D-III)).

Preparation Example 29 Formula

[0101]

[Chemical 10]

Preparation Example 26 except that a silicone polymer having a structure represented by the formula: wherein Me, Ph and A are as defined above was used and the formulation shown in Table 6 below was used.
A colorless and transparent varnish-like product was obtained in the same manner as in. Table 6 shows the nonvolatile content and acid value of the obtained silicone polymer having a hydroxyl group and a carboxyl group (hereinafter referred to as polymer (D-IV)).

[0103]

[Table 6]

Examples 1-56 In Examples 1-56, the polymers A-I-A-V, B-I-B-IV, C-I-C-VI and D- prepared in Preparation Examples 1-29. A coating composition containing the curable resin composition of the present invention obtained by using I to D-IV will be described.

Example 1 First, the coating composition of Example 1 was prepared with the formulations shown in the table below.

Composition Blend (parts by weight of solid content) Polymer AI (Preparation Example 6) 52 Polymer BI (Preparation Example 11) 48 Malic acid 2 additive ^{* 1} 5.2 Total 107.2 * 1: Tetrabutylammonium bromide / Tinuvin 960 / Sanol LS292 = 1.3 / 2.6 / 1.3 (parts by weight)

Then, the obtained coating composition was diluted with a solvent consisting of ethoxyethyl propionate / xylene = 1/1 (weight ratio) to a coating viscosity (Ford cup No. 4, 30 seconds, 20 ° C.), I got a clear paint. A test plate in which a cation-based electrodeposition paint (Power Top U-30 made by Nippon Paint Co., Ltd.) and an intermediate coating (Olga P-2 made by Nippon Paint Co., Ltd.) are coated on a phosphoric acid-treated steel plate is Super Rack made by Nippon Paint Co., Ltd. After applying the organic solvent type acrylic resin-based metallic base of M-90, the above clear paint is applied wet-on-wet and at 140 ° C for 3 hours.
Bake for 0 minutes. The cured coating film was evaluated by the evaluation methods shown in Table 7 below. The results are shown in Table 7. The dry film thickness of the clear coating was 40 μm.

Examples 2 to 56 Example 2 was carried out in the same manner as in Example 1 except that the coating compositions having the formulations shown in Table 7 below were used and the formulations shown in Table 7 were used.
~ 56 clear paints were prepared and the coating performance was evaluated.
The evaluation results are shown in Table 7.

Examples 57 to 58: Production of Resin for Aqueous Coating Production Example A (Production of Aqueous Acrylic Resin Varnish (A)) Ethylene glycol monobutyl ether was placed in a 1 liter reaction vessel equipped with a stirrer, a temperature controller and a cooling pipe. 76 parts were charged, and further, 15 parts of styrene, 63 parts of methyl methacrylate, 48 parts of 2-hydroxydiethyl methacrylate.
Parts, n-butyl acrylate 117 parts, methacrylic acid 2
61 parts of a monomer mixed solution consisting of 7 parts, 30 parts of acrylamide and 3 parts of azobisisobutyronitrile were added and the temperature was raised to 120 ° C. with stirring. After adding 245 parts of the above-mentioned monomer mixed solution in 3 hours, stirring was continued for 1 hour. Further, 28 parts of dimethylethanolamine and 200 parts of deionized water were added to obtain an aqueous acrylic resin varnish (A) having a volatile content of 50% and a resin number average molecular weight of 12,000.
This resin had an OH number of 70 and an acid number of 58.

Production Example B (Production of Aqueous Acrylic Resin Varnish (B)) 2- Ethoxypropanol was placed in a 3 liter reaction vessel equipped with a nitrogen inlet pipe, a temperature control unit, a dropping funnel, a stirrer and a cooling pipe equipped with a decanter. 500 parts were charged and the temperature was raised to 100 ° C. Styrene monomer 5 on the dropping funnel
0 parts, 50 parts of methyl methacrylate, 200 parts of 2-hydroxyethyl methacrylate, 120 parts of 2-ethylhexyl methacrylate, 380 parts of butyl acrylate and 100 parts of monobutyl maleate and 100 parts of acrylamide dissolved in 300 parts of methanol, and further polymerization. A solution consisting of 30 parts of azobisisobutyronitrile was charged as an initiator.
While keeping this solution at 100 ° C., a solution containing a monomer and an initiator was added dropwise over 3 hours while distilling methanol off with a decanter. After stirring for another 30 minutes, a solution containing 50 parts of butyl acetate and 3 parts of t-butylperoxy 2-ethylhexanoate was added dropwise over 0.5 hour. After the dropping, the temperature was maintained at 100 ° C. for 1.5 hours. During that time, 300 parts of methanol was distilled off. Then, 220 parts of the solvent was distilled off under reduced pressure. Further, 100 g of dimethylethanolamine and 570 g of deionized water were added and dissolved to obtain a nonvolatile content of 50
%, A transparent and viscous aqueous acrylic resin varnish (B) having a number average molecular weight of 10,000 was obtained.

Production Example C (Synthesis of Urethane Prepolymer) To a 1000 ml reaction vessel equipped with a thermometer, a stirrer and a condenser, 40.2 parts of dimethylolpropionic acid, 30 parts of triethylamine and 312 parts of N-methylpyrrolidone were added and the temperature was 90 ° C. It was heated to dissolve. Next, 290 parts of isophorone diisocyanate and 700 parts of polypropylene glycol (molecular weight: 1000) were added, and after stirring for 10 minutes, 1.03 parts of dibutyltin dilaurate was added. Next, the temperature was raised to 95 ° C. and the reaction was carried out for 1 hour to obtain a urethane prepolymer solution. (Preparation of Urethane Emulsion) 15000 parts of deionized water and 9.2 parts of hydrazine hydrate were added to a 5000 ml reaction vessel equipped with a thermometer, a stirrer, a condenser and a dropping funnel, and the urethane prepolymer obtained above was stirred. The solution was added. Then, the mixture was stirred for 30 minutes. The resulting composition was a cloudy, stable urethane emulsion. The acid value of the solid content was 16.2, and the obtained nonvolatile content was 33%.

Example 57: Aqueous metallic coating composition
Prepared aluminum pigment paste (Alpaste 7160N,
To 15 parts of an Al metal content of 65%, manufactured by Toyo Aluminum Co., Ltd., 30 parts of Cymel 303 (methoxylated methylol melamine resin manufactured by Mitsui Cyanamid Co., Ltd.) was added and uniformly mixed.
Further, 2 parts of isostearyl acid phosphate were uniformly mixed to obtain an aluminum pigment solution. Next, the aluminum pigment solution was added to 112 parts of the aqueous acrylic resin varnish (A) obtained in Production Example A and uniformly dispersed, and then 43 parts of the urethane emulsion obtained in Production Example C was uniformly dispersed to obtain an aqueous metallic paint. (1) was obtained. A test plate obtained in the same manner as in Example 1 was spray-coated with the above aqueous metallic paint and precoated at 60 ° C. for 5 minutes,
The clear coating composition of Example 24 was applied and cured at 140 ° C. for 30 minutes, and the same evaluation as in Example 1 was performed. The results are shown in Table 7.

Example 58 Production Example C of the aqueous acrylic resin varnish (A) of Example 57
To 80 parts of the aqueous acrylic resin varnish (B) obtained in step 3, 43 parts of the urethane emulsion was added, and the same urethane emulsion 91 was added.
Aqueous metallic paint (2) was obtained in the same manner as in Example 57 except that the parts were changed. The same coating and evaluation as in Example 57 were carried out except that the aqueous metallic paint (1) of Example 57 was replaced with the aqueous metallic paint (2) and the clear paint was replaced with the clear paint of Example 41. The results are shown in Table 7.

[0114] Except for using the formulation shown in Comparative Examples 1-8 The following Table 7 in the same manner as in Example 1, to prepare a clear coating of Comparative Example 1-8 were evaluated coating film performance. The evaluation results are shown in Table 7.

[0115]

[Table 7]

[0116]

[Table 8]

[0117]

[Table 9]

[0118]

[Table 10]

Preferred embodiments of the present invention are as follows. (1) In the coating composition or coating film forming method of the present invention,
Ingredient [I] / [II] = 100 parts by weight solid content / 0.2-4
A composition or method that is parts by weight of solids. (2) In the coating composition or coating film forming method of the present invention,
Component [I] / [II] = 100 parts by weight of solid content / 0.5 to 3
A composition or method that is parts by weight of solids. (3) In the coating composition or coating film forming method of the present invention,
The composition or method wherein the component [II] is at least one of glycolic acid, lactic acid, hydroacrylic acid, β-oxy acid, tartronic acid, malic acid, tartaric acid and citric acid. (4) In the coating composition or coating film forming method of the present invention,
A composition or method, wherein the component [II] is at least one of malic acid, lactic acid and glycolic acid. (5) In the coating composition or coating film forming method of the present invention,
A composition or method, wherein component [II] is at least one of malic acid and lactic acid. (6) In the coating composition or coating film forming method of the present invention,
Resin (A) / (B) = 100 solids weight part / 80-15
A composition or method which is 0 parts by weight solids. (7) In the coating composition or coating film forming method of the present invention,
Resin (A) / (B) / [(C) and / or (D)] = 2
A composition or method which is 5-55% by weight / 35-55% by weight / 5-40% by weight. (8) In the coating composition or coating film forming method of the present invention,
A composition or method comprising a coating composition further containing a quaternary ammonium salt catalyst. (9) The amount of the quaternary ammonium salt catalyst of the above (8) is 0.
A coating composition or a coating film forming method, wherein 1 to 2 parts by weight / 100 parts by weight of resin solid content. (10) The coating composition or the method for forming a coating film according to the present invention, wherein the coating composition further contains an organotin compound. (11) In the coating composition or coating film forming method of the present invention, the coating composition is resin (A) / (B) / [(C) and /
Or (D)] = 25 to 55% by weight / 35 to 55% by weight /
Component [I] / [II] = 100 solid parts by weight / 0.5 to 3 solid parts by weight at 5 to 40% by weight, and further the component [I]
I] is at least one of malic acid and lactic acid, and contains 0.1 to 2 parts by weight of a quaternary ammonium salt catalyst / 100 parts by weight of resin solids. (12) A coating composition or a method for forming a coating film, wherein the component [II] of (11) above is malic acid.

Claims (2)

[Claims] 1. A curable resin composition containing [I] the following (A) and (B) and optionally the following (C) and / or (D), and (A) (i) (1) Acid anhydride group-containing polymer obtained by copolymerizing 15 to 40% by weight of an acid anhydride group-containing ethylenically unsaturated monomer and (2) 60 to 85% by weight of another copolymerizable ethylenically unsaturated monomer And (ii) 1
A carboxyl group and a carboxylic acid ester obtained by reacting a monoalcohol containing 12 to 12 carbon atoms in an amount such that the acid anhydride group / hydroxyl group molar ratio is 1/10 to 1/1. Polymers having groups 20 to 6
0% by weight (% by weight of the polymer is based on the total weight of the solid content of the resin composition, the same applies hereinafter): and (B) (i) Formula (I) [Wherein, R is a hydrogen atom or a methyl group, X is a linear or branched alkyl or hydroxyalkyl, and m is 2 to
8 is an integer, n is an integer of 3 to 7, and q is 0 to 4
5 to 60% by weight of a hydroxyl group-containing ethylenically unsaturated monomer having a structure represented by the formula: (ii) an epoxy group-containing ethylenically unsaturated monomer of 10 to 60% by weight, and optionally (iii) other Polymer having a hydroxyl group and an epoxy group, obtained by copolymerizing 0 to 85% by weight of a copolymerizable ethylenically unsaturated monomer
0 to 60% by weight (however, when the components (C) and (D) are not included, the ratio of 50 to 250 parts by weight of the component (B) per 100 parts by weight of the solid content of the component (A)): Accordingly, 5 to 50% by weight of a polymer having a hydroxyl group and a carboxyl group of the following (C) and / or (D): (C) (i) The hydroxyl group-containing ethylenically unsaturated monomer and the acid anhydride group-containing compound are hydroxyl groups. / Carboxylic acid group-containing ethylenically unsaturated monomer and hydroxyl group-containing ethylenically unsaturated obtained by mixing and reacting in a molar ratio of 1 / 0.9 to 1 / 0.5 of acid anhydride group 20-100% by weight of monomer mixture with monomers, and optionally (ii) copolymerizable ethylenically unsaturated monomer 0
A polymer having a hydroxyl group and a carboxyl group, obtained by copolymerizing 80 to 80% by weight of (D) (i) formula (II) [Wherein R ¹ is a methyl, phenyl or phenylethyl group, and R ² and R ³ are independently methyl, phenyl, phenylethyl, 3-hydroxypropyl or 3
- a (hydroxyethoxy) propyl group, R ⁴ is methyl, 3-hydroxypropyl or 3- (hydroxyethoxy) propyl group, R ⁵ is methyl, phenyl, phenylethyl or isobutyl group, l is 1
Is an integer of -20, m is an integer of 2-4, and n is 0.
A hydroxyl group-containing silicone polymer having an average of 3 to 12 hydroxyl groups in one molecule, selected from the group consisting of compounds having a structure represented by the formula: Physical group-containing compound
A silicone polymer having a hydroxyl group and a carboxyl group [II] oxyacid, which is obtained by carrying out a half-esterification reaction in an amount such that the molar ratio of acid anhydride groups is 1 / 1.0 to 1 / 0.2. A coating composition comprising the curable resin composition (I) in an amount of 0.1 to 6 parts by weight of solid content of oxyacid (II) with respect to 100 parts by weight of solid content. 2. (i) a step of forming a base coating film by using a water-based or solvent-based base coating on an undercoated or under-coated and intermediate coated substrate; (ii) without curing the base coating, The step of applying the coating composition according to claim 1 to form a clear coating film; and (iii) heating to cure the base coating film and the clear coating film in this order. A method for forming a coating film, comprising: