JPH0156090B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a polyamideimide resin with improved heat resistance, and its purpose is to improve the heat resistance of the polyamideimide resin. [Conventional technology and problems] Polyamide-imide resin, which has been well known until now, has excellent electrical properties, heat resistance, and mechanical properties, so it has been used in electrical insulation varnishes and heat-resistant films. . However, for example, as a film for printed wiring boards, 260 to 280
It is desired to have something that can withstand soldering baths at ℃.
Currently commercially available polyamide resins have a problem with heat resistance in this solder bath. [Means and Effects for Solving the Problems] The present inventors added N-methylolated (meth)acrylamide or its derivative to a polyamideimide resin solution having carboxyl groups at a concentration of 1.0 per molar equivalent of carboxyl groups. By adding ~5.0 molar equivalent of bismaleimide compound to the reacted system and modifying it by adding 5 to 50% by weight of the polyamideimide resin, heat resistance can be improved without impairing other electrical properties. The present invention has been achieved based on the discovery that this can be improved. That is, in order to improve the heat resistance of carboxyl group-containing polyamideimide resin, it is possible to make the curing temperature even stricter, but in this case, the hydrogen atom on the nitrogen of the intermolecular amide bond and the carboxyl group are condensed. It has been found that due to this, the molecular weight between crosslinking points decreases, resulting in a significant decrease in folding durability. However, by condensing the carboxyl group with N-methylolated (meth)acrylamides, crosslinking between highly reactive acryloyl groups can proceed more easily without reducing the molecular weight between crosslinking points as described above. . For this reason, heat resistance can be improved without impairing folding durability. The polyamide-imide resin used in the present invention preferably has a carboxyl group, and this polyamide-imide resin having a carboxyl group can be synthesized by various methods. Among polyamide-imides synthesized from polybasic acid anhydrides and diisocyanates, polyamide-imide resins produced from aromatic polybasic acid anhydrides and aromatic diisocyanates are particularly preferred in order to improve heat resistance. For example, excess trimellitic anhydride and aromatic diisocyanate are reacted at 50 to 200°C for several hours. In this case, trimellitic anhydride is preferably used in an amount of 1.0 to 1.2 mol per mol of diisocyanate. This does not preclude the use of acid anhydrides in amounts greater than this, but if the amount of acid anhydrides is too large, only low molecular weight polyamide-imide resins will be obtained, which may be insufficient in strength when used as a film. It may happen. In addition, by the method described in Japanese Patent Publication No. 42-16080, polyamideimide having an isocyanate group at the end is synthesized, and this is reacted with excess trimellitic anhydride or pyromellitic anhydride to add carboxyl groups to the polyamideimide resin. can also be introduced. Generally, for polyamide-imide resins having carboxyl groups, it is convenient to use a mixture of aromatic diisocyanates, aromatic tribasic acid anhydrides, and in some cases aromatic tetrabasic acid anhydrides, and the heat resistance of the resulting resin Good results can also be obtained. As the aromatic diisocyanate, toluylene diisocyanate, diphenylmethane diisocyanate, diphenyl ether diisocyanate, etc. may be used alone or as a mixture thereof. Examples of the aromatic polybasic acid compound include trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, and the like.
The use of at least 50 mol% of trimellitic anhydride gives good results in terms of solubility. The amount is preferably mol % or less, preferably in the range of 0 to 40 mol %. During this polycondensation reaction, it is more convenient to use a solvent, such as dimethylformamide,
dimethylacetamide, dimethyl sulfoxide,
Aprotic polar solvents such as hexamethylphosphoricamide and N-methylpyrrolidone can be used alone or as a mixture. Furthermore, it is also possible to add aromatic hydrocarbons and ketones to the extent that the polyamide-imide resin does not precipitate. The above polycondensation reaction is preferably carried out at a temperature of 50 to 200°C, more preferably 100 to 180°C, and the carboxyl groups in the resulting polyamideimide resin are determined by potentiometric titration using sodium methylate. The thus obtained polyamide-imide resin having carboxyl groups preferably has at least four or more carboxyl groups in one molecule. This does not preclude the use of resins with fewer carboxyl groups, but the modification effect of adding N-methylolated (meth)acrylamides is small. The amount of N-methylolated (meth)acrylamide and its derivatives used is 1 carboxyl group.
It is preferred to use about 1.0 to 5.0 molar equivalents, more preferably about 1.0 to 2.0 molar equivalents. Examples of N-methylolated (meth)acrylamide and its derivatives include N-methylolated acrylamide, N-methoxyacrylamide, N-butoxyacrylamide, N-methylolated methacrylamide, and N-butoxymethacrylamide. These compounds can be used alone or in a mixture, but the total amount thereof is not preferably more than 5 molar equivalents per 1 molar equivalent of carboxyl group. Also, no more N-
The use of methylolated acrylamides deteriorates the folding durability of the resulting film. Polyamideimide with carboxyl group and N
- Reaction with methylolated (meth)acrylamides at a temperature of 50 to 200°C, preferably 100 to 150°C.
0.5 to 3 hours is appropriate. If the temperature is high, N-methylolated (meth)acrylamides may polymerize during the reaction, so preferably a polymerization inhibitor such as BHT is present in the range of 5 to 200 ppm to obtain favorable results. Can be done. The resulting polyamide-imide resin has the characteristic of radical curability, and as compared to the original resin, it can not only improve heat resistance but also improve the folding durability of the film. In the present invention, heat resistance can be further improved by further adding a bismaleimide compound to the polyamide-imide resin with improved heat resistance as described above. This bismaleimide compound is represented by the following general formula. [In the formula, X represents _CH2 , O, _SO2 , S, C( _CH3 ) ₂ ] Carbon-carbon double bond of bismaleimide and carbon-carbon double bond of N-methylolated (meth)acrylamides Since the bonds are copolymerized, the resulting film is transparent and has excellent heat resistance. The amount of bismaleimide added is in the range of 5 to 50% by weight based on the polyamideimide resin. If it is less than 5% by weight, the effect of improving heat resistance will be small, while if it exceeds 50% by weight, the folding durability of the film will deteriorate. When making a film, azo compounds such as azobisisobutyronitrile and azobisvaleronitrile, and peroxides such as di-t-butyl peroxide and benzoyl peroxide are added to speed up film formation. It can also be heated to 150℃.
When a film is formed at the above temperature, the desired polyamide-imide resin film can be obtained by heating alone even in the absence of these radical initiators. EXAMPLES The present invention will be specifically described below with reference to Examples and Reference Examples, but the present invention is not limited to these Examples. Synthesis of polyamide-imide resin 0.95 mol of diphenylmethane diisocyanate and 1.00 mol of trimellitic anhydride were replaced with nitrogen.
Pour into a three-necked flask and add N-methyl-2-
1200 ml of pyrrolidone was added. With stirring, the reaction mixture was incubated at 100°C for 1.5 hours and at 130°C for 2 hours at 180°C.
The reaction was carried out at ℃ for 6 hours. The viscosity of the N-methyl-2-pyrrolidone solution of this polyamideimide resin was 2000 centipoise at room temperature. Synthesis of polyamide-imide resin 1.02 mol of diphenylmethane diisocyanate and 1.00 mol of trimellitic anhydride were replaced with nitrogen.
Pour into a three-necked flask and add N-methyl-2-
Added 1200ml of pyrrolidone. The reaction mixture was reacted at 100°C for 1 hour, 130°C for 2 hours, and further at 180°C for 4 hours, and then 0.04 mol of pyromellitic anhydride was added and the reaction was continued at 130°C for 2 hours. This resin's N-
The viscosity of methyl-2-pyrrolidone solution at room temperature is
It was 14,000 centipoise. Reference Examples 1 to 3 N-methylolated acrylamide was added to a solution of the above polyamide-imide resin and a commercially available polyamide-imide resin (HI-400 manufactured by Hitachi Chemical), and the mixture was treated at 120°C for 1 hour in the presence of 10 ppm of BHT. . After cooling to room temperature, 2% by weight of benzoyl peroxide was added. The obtained resin solution was applied on a glass plate and heated at 180°C.
Table 1 summarizes the results of producing a corresponding film by raising the temperature to ~280°C for 30 minutes.

【table】

[Table] Examples 1 to 5 Films were prepared in the same manner by adding bismaleimide to the resins of Reference Example 2 and Reference Example 3, and the heat resistance was examined. The results are summarized in Table 2.

【table】

【table】

Claims (1)

[Claims] 1. N-
Methylorated (meth)acrylamide or its derivatives per molar equivalent of carboxyl group,
1. A method for producing a heat-resistant resin, which comprises adding 1.0 to 5.0 molar equivalents to cause a reaction, and then adding a bismaleimide compound to the reaction system in an amount of 5 to 50% by weight based on the polyamideimide resin for modification. 2. The manufacturing method according to claim 1, wherein the bismaleimide compound is represented by the following general formula. [In the formula, X represents CH ₂ , O, SO ₂ , S, C(CH ₃ ) ₂ ]