JPH08120175A - Polyamide-imide resin composition and heat resistant paint - Google Patents

Abstract

PURPOSE: To obtain the subject composition excellent in low-temperature curability and storage stability by compounding a modified polyamide-imide resin obtained by reacting a polyamide-imide resin with a specific bisoxazoline compound with an epoxy resin. CONSTITUTION: This composition is composed of (A) 100 pts.wt. of a modified polyamide-imide resin (preferably, its acid value is <2KOHmg/g) obtained by reacting a polyamide-imide resin with a bisoxazoline compound of the formula (R1 , R2 , R4 and R5 are each H, a lower alkyl, etc.; R3 and R6 are each H, a phenyl, etc.; X is a 1-8C alkylene or a phenylene; m=0, 1) [e.g. 2,2'-bis(2-oxazoline)] and (B) 1-50 pts.wt. of an epoxy resin. The polyamide-imide resin constituting the component A is obtained e.g. by reacting a trivalent or higher valent polycarboxylic acid anhydride with an aromatic diisocyanate or an aromatic diamine, wherein trimellitic anhydride is preferable as the polycarboxylic acid anhydride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide-imide resin composition and a heat resistant coating, and more particularly to a low temperature curable polyamide-imide resin composition and a heat resistant coating.

[0002]

2. Description of the Related Art Polyamide-imide resins have excellent heat resistance, chemical resistance, solvent resistance, abrasion resistance, etc., and are widely used as varnishes for enameled wires and heat-resistant paints as coating agents for various base materials. Has been done. However, in order to obtain these excellent properties, it is necessary to cure at a high temperature. For example, when baking an enamel wire, the temperature is usually 300 ° C. or higher, and even when it is used in a heat resistant coating, it is usually 250 ° C. or higher. It has been cured. On the other hand, in the field of heat-resistant coating materials, it is desired to reduce the curing temperature for preventing the hardness reduction of the surface substrate and for improving the dimensional accuracy as the substrate becomes aluminum due to the weight reduction of the members. The addition of an epoxy resin has been studied in order to lower the curing temperature of the polyamide-imide resin, but the storage stability becomes poor and the range of use is limited.

[0003]

DISCLOSURE OF THE INVENTION As a result of intensive studies, the present inventors have found that after reacting a carboxyl group remaining in a polyamide-imide resin with a bisoxazoline compound, an epoxy resin is added, The present invention has been accomplished by finding that the above problems can be solved. The present invention provides a polyamideimide resin composition and a heat resistant coating which are excellent in low temperature curability and storage stability.

[0004]

That is, the present invention provides 100 parts by weight of a modified polyamideimide resin obtained by reacting a polyamideimide resin with a bisoxazoline compound represented by the following general formula (I) and 1 to 50 parts by weight of an epoxy resin. TECHNICAL FIELD The present invention relates to a polyamide-imide resin composition containing parts and a heat-resistant paint using the composition.

Embedded image (In the formula, R ₁ , R ₂ , R ₄ and R ₅ are each independently hydrogen,
Selected from the group consisting of a lower alkyl group, a phenyl group and a hydroxymethyl group, R ₃ and R ₆ are each independently selected from the group consisting of hydrogen, a methyl group and a phenyl group,
X is selected from the group consisting of an alkylene group having 1 to 8 carbon atoms and a phenylene group, and m is an integer of 0 or 1.)

Polyamideimide resin is disclosed in Japanese Patent Publication No. 44-19
Manufactured by the already known manufacturing method shown in Japanese Patent Application Publication No. 274, etc., for example, tricarboxylic or higher polycarboxylic acid having an acid anhydride group or a derivative thereof and aromatic diisocyanate or aromatic diamine in an organic polar solvent. Obtained by reacting. Examples of the tricarboxylic or higher polycarboxylic acid having an acid anhydride group or a derivative thereof include those represented by the general formula (II) or (II
A compound represented by I) can be used, and a trivalent or higher polycarbohydrate having an acid anhydride that reacts with an isocyanate group or an amino group.

Embedded image (In both formulas, R represents hydrogen, an alkyl group or a phenyl group, and Y represents —CH ₂ —, —CO—, —SO ₂ —, or —O—). There is no limit. Considering heat resistance and cost, trimellitic anhydride is most preferable. If necessary, a part of this may be pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, bicyclo- [2,2,2] -oct-7-ene-2: 3: 5: 6
It may be replaced with a tetracarboxylic acid dianhydride such as tetracarboxylic acid dianhydride, an aliphatic or aromatic dibasic acid and the like.

Examples of aromatic diisocyanates include 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenyl ether diisocyanate,
4,4 '-[2,2-bis (4-phenoxyphenyl)
Propane] diisocyanate or the like can be used,
These can also be used in combination. You may use a polyisocyanate that has been synthesized in advance,
You may use what was stabilized with the suitable blocking agent in order to avoid a secular change. Examples of aromatic diamines include 4,4′-diaminodiphenylmethane and 4,4′-
Diaminodiphenyl ether, m-xylenediamine,
Toluylenediamine, p-phenylenediamine, 2,2
-Bis [4- (4-aminophenoxy) phenyl] propane and the like can be used, and these can also be used in combination.

The amount of the above polycarboxylic acid or derivative thereof and the aromatic diisocyanate or aromatic diamine used is
It is preferable to select such that the ratio of the isocyanate group or amino group to the carboxyl group or its derivative group and the acid anhydride group is 1.5 to 0.7. In order to obtain a high molecular weight resin, the carboxyl group or The ratio of the isocyanate group or the amino group to the derivative group and the acid anhydride group is 1.
It is preferably around 0.

The reaction is carried out by heating and condensing in the temperature range of 80 to 150 ° C. in the presence of an organic polar solvent while removing carbon dioxide gas which is liberated in the case of aromatic diisocyanate from the reaction system. The reaction time is appropriately selected depending on the scale of the batch and the reaction conditions adopted.

Examples of the organic polar solvent include N-methyl-2-pyrrolidone, N, N-dimethylformamide,
N, N-dimethylacetamide, dimethylsulfoxide, γ-butyrolactone, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether and the like can be used alone or in combination of two or more thereof, and the amount thereof is 1. 0 to 5.0 times (weight) is preferable.

When the aromatic diisocyanate is used after the synthesis of the polyamide-imide resin, the isocyanate group at the terminal of the resin can be blocked with a blocking agent such as alcohols, lactams and oximes.

The polyamide-imide resin in the present invention preferably has an acid value (KOHmg / g) of 1 to 100, more preferably 5 to 60, particularly preferably 10 to 50.

Examples of the bisoxazoline compound represented by the general formula (I) in the present invention include 2,2'-bis (2-oxazoline), 5,5'-dimethyl-2,
2'-bisoxazoline, 4,4,4 ', 4'-tetramethyl-2,2'-bisoxazoline, 4,4'-diethyl-2,2'-bisoxazoline, 2,2'-methylenebis (2 -Oxazoline), 2,2'-ethylenebis (2-oxazoline), 2,2'-ethylenebis (4,
4-dimethyl-2-oxazoline), 2,2'-trimethylenebis (4,4-dimethyl-2-oxazoline),
2,2'-tetramethylene bis (4,4-dimethyl-2
-Oxazoline), 2,2'-pentamethylenebis (4,4-dimethyl-2-oxazoline), 2,2'-
Hexamethylenebis (4,4-dimethyl-2-oxazoline), 2,2'-heptamethylenebis (4,4-dimethyl-2-oxazoline), 2,2'-octamethylenebis (4,4-dimethyl-) 2-oxazoline), 2,
2'-ethylenebis (4-methyl-2-oxazoline), 2,2'-trimethylenebis (4-methyl-2-
Oxazoline), 2,2'-tetramethylenebis (4-
Methyl-2-oxazoline), 2,2′-pentamethylenebis (4-methyl-2-oxazoline), 2,2′-
Hexamethylene bis (4-methyl-2-oxazoline), 2,2'-heptamethylene bis (4-methyl-2)
-Oxazoline), 2,2'-tetramethylenebis (5
-Methyl-2-oxazoline), 2,2'-tetramethylenebis (4,4-diphenyl-2-oxazoline),
2,2'-tetramethylenebis-2-oxazoline-4
-Methanol, 2,2'-tetramethylenebis-2-oxazoline-4,4'-dimethanol, 2,2'-tetramethylenebis-2-oxazoline, 2,2'-octamethylenebis-2-oxazoline, 2,2'-tetramethylenebis [4- (hydroxymethyl) -4-methyloxazoline], 2,2'-heptamethylenebis [4-
(Hydroxymethyl) -4-methyloxazoline],
2,2 '-(1,3-phenylene) bis (2-oxazoline), 2,2'-p-phenylenebis-2-oxazoline, 2,2'-p-phenylenebis (4,4-dimethyl-2) -Oxazoline), 2,2'-p-phenylenebis (5-phenyl-2-oxazoline) and the like.

The amount of the bisoxazoline compound represented by the general formula (I) to be used is preferably an equivalent amount or more with respect to the terminal carboxyl group of the polyamideimide resin. If the amount of the bisoxazoline compound used is less than this, the storage stability of the polyamideimide resin composition to which the epoxy resin is added tends to decrease.

The reaction between the polyamideimide resin and the bisoxazoline compound, that is, the reaction between the carboxyl group and the oxazoline, is 50 to 50, as described in US Pat. No. 3,476,712 and JP-A-2-120325.
It can be carried out in the presence of an organic polar solvent in the temperature range of 200 ° C. The reaction time is appropriately selected depending on the scale of the batch and the reaction conditions adopted. As the organic polar solvent, for example, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, γ-butyrolactone, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether or the like alone or 2 They may be used in combination of two or more kinds, and the organic polar solvent used for the synthesis of the above-mentioned polyamide-imide resin may be used as it is. The amount of the used modified polyamideimide resin is 1.0 to
It is preferably 5.0 times (weight).

The modified polyamide-imide resin in the present invention preferably has an acid value (KOHmg / g) of less than 5, and more preferably less than 2.

The epoxy resin used in the present invention is not particularly limited, and for example, Yuka Shell Epoxy Co., Ltd.
Made by Epicoat 815, 825, 827, 828, 83
4, 1001, 1004, 1007, 1009 and other bisphenol A type epoxy resins, Epicoat 152, 15
4. Phenolic novolac type epoxy resins such as EPPN-201 manufactured by Nippon Kayaku Co., Ltd. and DEN-438 manufactured by Dow Chemical Co., Ltd., EOCN-102S manufactured by Nippon Kayaku Co., Ltd., 10
3S, 104S and other o-cresol novolac type epoxy resins, Epon 103 manufactured by Yuka Shell Epoxy Co., Ltd.
1S, Ciba Geigy Araldite 0163, Nagase Kasei Denacol EX-611, EX-614,
EX-614B, EX-622, EX-512, EX-
521, EX-421, EX-411, EX-321 and other multifunctional epoxy resins, Tohto Kasei Co., Ltd. YH-43
4, Yuka Shell Epoxy Co., Ltd. Epicoat 604, Mitsubishi Gas Chemical Co., Ltd. TETRAD-X, TETRAD-
C, GAN manufactured by Nippon Kayaku Co., Ltd., ELM manufactured by Sumitomo Chemical Co., Ltd.
Amine type epoxy resin such as −120, heterocyclic ring containing epoxy resin such as Araldite PT810 manufactured by Ciba Geigy, ERL4234, 4299, 422 manufactured by UCC
Alicyclic epoxy resins such as 1,4206 can be used, and one kind or two or more kinds of them can also be used. The amount of the epoxy resin used is 1 to 50 parts by weight, and preferably 2 to 30 parts by weight, based on 100 parts by weight of the modified polyamideimide resin obtained by reacting the polyamideimide resin with a bisoxazoline compound. If the amount of epoxy resin used is less than 1 part by weight, low temperature curability will decrease,
If the amount is more than 50 parts by weight, the adhesion of the cured product to the substrate will be reduced.

As a method of adding the epoxy resin, the epoxy resin to be added may be previously dissolved in the same solvent as the solvent contained in the modified polyamideimide resin, and then added.
Alternatively, it may be directly added to the modified polyamide-imide resin.

The polyamideimide resin composition according to the present invention comprises N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, γ-butyrolactone, diethylene glycol dimethyl ether and triethylene glycol dimethyl ether. 10-40% by weight of resin content in organic polar solvents such as
It can also be used as a diluted solution. In this case, xylene, NISSEKI HISOL-100, 150, as a cosolvent, in consideration of the resin content concentration and viscosity,
Butyl acetate, cellosolve acetate, butyl cellosolve acetate, methyl ethyl ketone, ethylbenzene, p-cymene and the like may be used in combination.

An amine-based additive may be added to the polyamide-imide resin composition of the present invention in order to improve its curability. Examples of the amine-based additive include 4,4′-diaminodiphenylmethane and 4,4′-
Primary amines such as diaminodiphenyl ether and p-phenylenediamine, secondary amines such as piperidine and pyrrolidine, N, N, N ', N'-tetramethylhexamethylenediamine, N, N, N', N'- Tetramethylpropylenediamine, N, N, N ', N ", N" -pentamethyldiethylenetriamine, trimethylaminoethylpiperazine, N, N'-dimethylcyclohexylamine,
Bis (2-dimethylaminoethyl) ether, N,
N ', N "-tris (3-dimethylaminopropyl) hexahydro-s-triazine, N, N-dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N-trioxyethylene-N, N-dimethylamine , Triethylenediamine, 1,8-diazabicyclo (5.4.0) undecene-7, N, N, N-tris (3-dimethylaminopropyl) amine, N-methyldicyclohexylamine, N-methyl-N, N- Screw (3
-Dimethylaminopropyl) amine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, N, N'-dimethylpiperazine, pyridine, picoline, 1,2,2,6. A tertiary amine such as 6-pentamethyl-4-piperidinol or triethylamine, dicyandiamide or the like can be used.

The polyamide-imide resin composition according to the present invention is mainly used as a heat-resistant paint by mixing with the above-mentioned organic polar solvent, but it is used for other purposes, for example, varnish for enameled wire, impregnated varnish for electrical insulation. It can also be used as a sheet varnish combined with a base material such as a cast varnish, mica and glass cloth, an MCL laminated plate varnish, and a friction material varnish.

[0021]

EXAMPLES The present invention will be described below with reference to comparative examples and examples, but the present invention is not limited thereto. Comparative Example 1 N-methyl-2-pyrrolidone 7 was placed in a 2-liter four-necked flask equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer.
47 g, 4,4'-diphenylmethane diisocyanate 298 g (1.19 mol) and trimellitic anhydride 22
7 g (1.18 mol) was charged and the temperature was raised to 130 ° C. When reacted for about 4 hours, the number average molecular weight was 17,0.
A resin having an acid value of 00 and an acid value of 30 KOHmg / g was obtained. This resin was diluted with a mixed solvent of 70 parts by weight of N-methyl-2-pyrrolidone and 30 parts by weight of N, N-dimethylformamide to obtain a polyamideimide resin varnish having a nonvolatile content of 30% by weight.

Comparative Example 2 In the same flask as in Comparative Example 1, 703 g of N-methyl-2-pyrrolidone, 281.7 g (1.13 mol) of 4,4'-diphenylmethane diisocyanate and 213.1 g of trimellitic anhydride (1. 11 mol), 130 ℃
The temperature was raised to. After reacting for about 6 hours, a resin having a number average molecular weight of 23,000 and an acid value of 20 KOHmg / g was obtained.
This resin was diluted with a mixed solvent of 75 parts by weight of N-methyl-2-pyrrolidone and 25 parts by weight of xylene to obtain a nonvolatile content of 25
A weight% polyamide imide resin varnish was obtained.

Comparative Example 3 23.1 parts by weight of 2,2 '-(1,3-phenylene) bis (2-oxazoline) based on 100 parts by weight of the resin component of the polyamide-imide resin varnish obtained in Comparative Example 1. (4 equivalents to the terminal carboxyl group of the polyamide-imide resin) was added and the temperature was raised to 100 ° C. After reacting for about 3 hours, the number average molecular weight was 22,000 and the acid value was 1.3 KO.
A modified polyamideimide resin of Hmg / g was obtained. After cooling to room temperature, the mixture was diluted with a mixed solvent of 70 parts by weight of N-methyl-2-pyrrolidone and 30 parts by weight of N, N-dimethylformamide to obtain a modified polyamideimide resin varnish having a nonvolatile content of 30% by weight.

Comparative Example 4 In Comparative Example 3, 2,2 '-(1,3-phenylene)
The same operation as in Comparative Example 3 was repeated except that the amount of bis (2-oxazoline) was changed to 34.7 parts by weight (6 times the equivalent of the terminal carboxyl group of the polyamideimide resin), and the number average molecular weight was 22,000. A modified polyamideimide resin varnish having an acid value of 0.9 KOHmg / g was obtained.

Comparative Example 5 In Comparative Example 3, 2,2 '-(1,3-phenylene)
Except that the amount of bis (2-oxazoline) was changed to 5.2 parts by weight (0.9 times equivalent to the terminal carboxyl group of polyamideimide resin), the same operation as in Comparative Example 3 was carried out to obtain a number average molecular weight of 23, A modified polyamideimide resin varnish having an acid value of 30,000 and an acid value of 10.3 KOHmg / g was obtained.

Comparative Example 6 2,4 '-(1,3-phenylene) bis (2-oxazoline) 15.4 parts by weight based on 100 parts by weight of the resin component of the polyamide-imide resin varnish obtained in Comparative Example 2. (4 equivalents to the terminal carboxyl group of the polyamide-imide resin) was added and the temperature was raised to 100 ° C. After reacting for about 3 hours, the number average molecular weight was 25,000 and the acid value was 1.1 KO.
A modified polyamideimide resin of Hmg / g was obtained. After the temperature was lowered to room temperature, it was diluted with a mixed solvent of 75 parts by weight of N-methyl-2-pyrrolidone and 25 parts by weight of xylene to obtain a nonvolatile content of 25
A modified polyamide-imide resin varnish of weight% was obtained.

Example 1 YH-434 (Tohto Kasei) was added to 100 parts by weight of the resin content of the modified polyamideimide resin varnish obtained in Comparative Example 3.
Brand name, amine type epoxy resin, epoxy equivalent 1
21) 10 parts by weight were diluted with a mixed solvent of 70 parts by weight of N-methyl-2-pyrrolidone and 30 parts by weight of N, N-dimethylformamide to make a nonvolatile content of 30% by weight, and the nonvolatile content was 30%. A modified polyamide imide resin composition of weight% was obtained.

Example 2 In Example 1, 10 parts by weight of YH-434 was added to TET.
RAD-X (trade name, N, N, manufactured by Mitsubishi Gas Chemical Co., Inc.)
N ', N'-Tetraglycidyl-m-xylenediamine, epoxy equivalent 100) 10 parts by weight was carried out in the same manner as in Example 1 to obtain a modified polyamideimide resin composition having a nonvolatile content of 30% by weight. Obtained.

Example 3 Example 3 was repeated except that 10 parts by weight of YH-434 was changed to 10 parts by weight of Denacol EX-411 (trade name, manufactured by Nagase Kasei Kogyo KK, tetrafunctional epoxy resin, epoxy equivalent 231). The same operation as in Example 1 was performed to obtain a modified polyamideimide resin composition having a nonvolatile content of 30% by weight.

Example 4 Example 3 was repeated except that 10 parts by weight of YH-434 was changed to 10 parts by weight of Denacol EX-321 (trade name, manufactured by Nagase Kasei Kogyo Co., Ltd., trifunctional epoxy resin, epoxy equivalent 145). The same operation as in Example 1 was performed to obtain a modified polyamideimide resin composition having a nonvolatile content of 30% by weight.

Examples 5 and 6 The procedure of Example 4 was repeated, except that the addition amount of Denacol EX-321 was changed to 5 parts by weight and 3 parts by weight, respectively, and the nonvolatile content was 30% by weight. A modified polyamideimide resin composition of was obtained.

Example 7 Denacol EX-321 was added to 100 parts by weight of the resin content of the modified polyamideimide resin varnish obtained in Comparative Example 4.
10 parts by weight was diluted with a mixed solvent of 70 parts by weight of N-methyl-2-pyrrolidone and 30 parts by weight of N, N-dimethylformamide to make a nonvolatile content 30% by weight, and the nonvolatile content was 30% by weight. A modified polyamideimide resin composition of was obtained.

Example 8 Denacol EX-321 was added to 100 parts by weight of the resin content of the modified polyamideimide resin varnish obtained in Comparative Example 5.
10 parts by weight was diluted with a mixed solvent of 70 parts by weight of N-methyl-2-pyrrolidone and 30 parts by weight of N, N-dimethylformamide to make a nonvolatile content 30% by weight, and the nonvolatile content was 30% by weight. A modified polyamideimide resin composition of was obtained.

Example 9 Denacol EX-321 was added to 100 parts by weight of the resin content of the modified polyamideimide resin varnish obtained in Comparative Example 6.
A modified polyamideimide resin having a nonvolatile content of 25% by weight is added by diluting 10 parts by weight of a mixed solvent of 75 parts by weight of N-methyl-2-pyrrolidone and 25 parts by weight of xylene to a nonvolatile content of 25% by weight. A composition was obtained.

Comparative Example 7 Denacol EX-321 1 was added to 100 parts by weight of the resin component of the polyamide-imide resin varnish obtained in Comparative Example 1.
0 parts by weight was diluted with a mixed solvent of 70 parts by weight of N-methyl-2-pyrrolidone and 30 parts by weight of N, N-dimethylformamide to make the nonvolatile content 30% by weight, and the nonvolatile content was 30% by weight. A modified polyamideimide resin composition of was obtained.

Comparative Example 8 Denacol EX-321 was added to 100 parts by weight of the resin content of the modified polyamideimide resin varnish obtained in Comparative Example 2.
10 parts by weight was diluted with a mixed solvent of 70 parts by weight of N-methyl-2-pyrrolidone and 30 parts by weight of N, N-dimethylformamide to make a nonvolatile content 30% by weight, and the nonvolatile content was 30% by weight. A modified polyamideimide resin composition of was obtained.

Comparative Examples 9 and 10 The same operation as in Example 4 was carried out except that the addition amount of Denacol EX-321 was changed to 0.9 parts by weight and 55 parts by weight in Example 4, respectively. A modified polyamide imide resin composition of weight% was obtained.

The properties of the polyamideimide resin compositions obtained in the above Comparative Examples and Examples were measured by the following methods, and the results are shown in Tables 1 and 2. (1) Curability The polyamideimide resin composition was applied on a glass plate and then cured at 180 ° C. for 60 minutes. This is N-methyl-
It was evaluated by the extraction rate when immersed in 2-pyrrolidone at 40 ° C. for 2 hours (film thickness: 20 μm, size of test piece: 20 × 5).
0 mm).

(2) Storage stability It was evaluated by the rate of change in viscosity after standing at 40 ° C. for one month (measured with a B-type viscometer). (3) Adhesion The polyamideimide resin composition was applied on an aluminum plate, cured at 180 ° C. for 60 minutes, and evaluated by the cross-cut residual rate after immersion in a 1% sodium hydroxide aqueous solution (film thickness: 2
0 μm, 5 times peeling method).

From the results shown in Tables 1 and 2, it is shown that the polyamideimide resin composition of the present invention is excellent in low temperature curability, storage stability and adhesion of the cured product.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

The polyamide-imide resin composition of the present invention has excellent low-temperature curability and excellent properties of the obtained cured product. Therefore, when used as a heat-resistant coating, the curing temperature can be lowered. When a lightweight base material such as aluminum is used as the surface base material, it can be expected to prevent the hardness from decreasing and improve the dimensional accuracy.

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Claims (3)

[Claims] 1. A polyamide-imide resin composition comprising 100 parts by weight of a modified polyamide-imide resin obtained by reacting a polyamide-imide resin with a bisoxazoline compound represented by the general formula (I) and 1 to 50 parts by weight of an epoxy resin. Stuff. Embedded image (In the formula, R ₁ , R ₂ , R ₄ and R ₅ are each independently hydrogen,
Selected from the group consisting of a lower alkyl group, a phenyl group and a hydroxymethyl group, R ₃ and R ₆ are each independently selected from the group consisting of hydrogen, a methyl group and a phenyl group,
X is selected from the group consisting of an alkylene group having 1 to 8 carbon atoms and a phenylene group, and m is an integer of 0 or 1.) 2. A resin content of 10 to 40 depending on the organic polar solvent.
The polyamide-imide resin composition according to claim 1, which is diluted to a weight percentage. 3. A heat resistant coating containing the polyamideimide resin composition according to claim 1 and an organic polar solvent.