JPS6340811B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyamideimide. More specifically, the present invention relates to a method for producing polyamideimide, which comprises subjecting a tribasic acid anhydride and a diisocyanate compound to a polycondensation reaction in the presence of a tertiary amine catalyst. In recent years, so-called polyamide-imide resins having amide bonds and imide bonds in their main chains have attracted attention because of their excellent heat resistance, mechanical properties, electrical properties, and the like. Polyamide-imide is produced by a low-temperature solution polycondensation method between a tribasic acid monohalide anhydride and a diamine, and a melt or solution polycondensation method (Tokuko Showa) between a tribasic acid anhydride and a diisocyanate compound.
44-19274). The former reaction is a two-step reaction and hydrogen chloride is produced as a by-product, so it cannot be said to be very preferable. On the other hand, the latter reaction can be said to be an excellent method, not only because the reaction is in one step, but also because the generated carbon dioxide gas can be easily removed from the system. In the reaction of tribasic acid anhydrides and diisocyanate compounds carried out in the presence of tertiary amine contact,
In order to obtain high molecular weight polyamide-imide, the necessary conditions for the solvent used are that it be inert to the polymerization reaction, be able to dissolve at least one of the raw materials, have a high boiling point, and have a low dielectric constant. Examples include big things. in particular,
Amide solvents such as N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methyl-2-pyrrolidone, and nitrobenzene are commonly used. A resin with a molecular weight of about 0.5 can be obtained directly as a solution, but a high molecular weight product cannot be obtained. Also,
Nitrobenzene solvents tend to yield high molecular weight products with an intrinsic viscosity of about 1.0, but this does not dissolve in the solvent and is obtained as a precipitate, so when using the resulting polyamideimide as a varnish, it is difficult to There is an inconvenience in that it must be dissolved in a suitable solvent, and this solvent is also limited to N-methyl-2-pyrrolidone etc. due to the poor solubility of high molecular weight substances. The present inventor has conducted various studies in search of a solvent that can produce high molecular weight polyamideimide and also obtain the produced high molecular weight polyamideimide directly as a resin solution. It has been found that 1-dioxide (melting point: 27.4-27.8°C, boiling point: 285°C, viscosity at 30°C: 10.34 cps) satisfies these objectives. Therefore, the present invention relates to a method for producing polyamideimide, which is produced by polycondensing a tribasic acid anhydride and a diisocyanate compound in the presence of a tertiary amine catalyst, and performing the reaction in a sulfolane solvent. Manufactured by doing. Tribasic acid anhydrides include trimellitic anhydride, 1,2,3-benzenetricarboxylic anhydride, 1,2,5-naphthalenetricarboxylic anhydride, and 3,3',4-tricarboxybenzophenone anhydride. dibasic acids such as isophthalic acid and terephthalic acid (approximately 50 mol% or less) or dibasic acids such as pyromellitic dianhydride and benzophenonetetracarboxylic dianhydride. It can also be used by replacing it with a tetrabasic acid dianhydride (approximately 30 mol% or less). As the diisocyanate compound, diphenylmethane diisocyanate, diphenyl ether diisocyanate, 2,4-tolylene diisocyanate,
2,6-tolylene diisocyanate, biphenylene diisocyanate, m-phenylene diisocyanate, 1,5-naphthalene diisocyanate, or mixtures thereof are used. and,
These tribasic acid anhydride and diisocyanate compound are subjected to the reaction in substantially equimolar amounts. Tertiary amines used as reaction catalysts include:
1,8-diazabicyclo[5,4,0]undecene-7,1,4-diazabicyclo[2,2,2]
Octane, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyl-1,3-diaminobutane, N,N'-diethylpiperazine, triethylamine or their inorganic acids A salt or the like is used in a proportion of about 0.1 to 20 mol%, preferably about 0.2 to 18 mol%, based on the acid component. Sulfolane used as a solvent is preferably purified by distillation over granular sodium hydroxide and dried before use, but it may be purified by other methods. The polycondensation reaction is carried out using sulfolane as a solvent in an amount that is, for example, about 3 to 20 times the total solid weight used in the reaction, preferably about 10 to 20% (by weight) of the resulting polymer. The reaction is carried out at a reaction temperature of about 120 to 150°C, while the carbon dioxide gas generated is successively removed. The polyamideimide produced as a result of the reaction is obtained as a sulfolane solution, which can be used as it is as a varnish by adding necessary additives. However, due to the relationship with the melting point of sulfolane, it becomes opaque below about 25℃, but if you add a small amount of dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, etc. to dilute it, it becomes stable even at about 25℃. form a solution state. Moreover, at temperatures above about 30°C, a transparent solution state is formed. While thus obtained in the form of a solvent solution, the polyamideimide forms a polymer of high molecular weight, so that when a film is formed from it, for example, a film with good physical properties is obtained therein. . Next, the present invention will be explained with reference to examples. Example A stirrer, a reflux tube with a calcium chloride tube, a nitrogen gas introduction tube, and a thermometer were attached to a four-necked flask with a capacity of 500 ml, and 19.2 g of trimellitic anhydride was placed in the flask.
(0.1 mol), diphenylmethane diisocyanate
25.0 g (0.1 mol) and 270 g of sulfolane were charged in a nitrogen gas atmosphere and heated until the internal temperature of the flask reached 140°C. When the ingredients are uniform, add 2.0 g (0.018 mol) of 1,4-diazabicyclo[2,2,2]octane and continue heating and stirring while maintaining this temperature, the viscosity of the solution will increase rapidly. , carbon dioxide gas begins to be generated. When the reaction in this state was continued for 3 hours, a pale yellow polyamideimide solution was obtained. A certain amount of this polyamide-imide solution was precipitated with acetone, and the precipitated resin was further washed with acetone and then dried (yield 98%). The intrinsic viscosity of this is 1.52 (0.5 g/dl N-methyl-2-pyrrolidone,
(30°C), it was confirmed by infrared absorption spectrum measurement that it had a polyamideimide structure. In addition, when the polyamide-imide solution was cast onto a glass plate and dried (drying with ventilation at 120°C for 1 hour, and then drying under reduced pressure at 100 to 120°C/2 mmHg or less for 1 hour), it was found to be flexible and strong. A good film was obtained. Comparative Example 1 In the example, 100 g of N,N'-dimethylacetamide was used instead of sulfolane as the reaction solvent. When measuring the intrinsic viscosity of the resin precipitated with acetone from the obtained polyamide-imide solution,
0.445 (0.5g/dlN, N'-dimethylacetamide,
30℃) was obtained. Furthermore, a flexible film was obtained from the polyamide-imide solution. Comparative Example 2 In Example, when 200 g of nitrobenzene was used instead of sulfolane as a reaction solvent, 1,4-diazabicyclo[2,2,2] as a catalyst
A precipitate separates out about 20 minutes after adding octane. 3
After continuing the reaction for an hour, the precipitate is redispersed in acetone, washed two to three times with acetone, and dried (yield 98%). When the intrinsic viscosity of this resin was measured, a value of 1.04 (0.5 g/dl N-methyl-2-pyrrolidone, 30°C) was obtained;
- A flexible film was obtained from the pyrrolidone solution. The tensile strength and elongation values of the films obtained in the above examples and comparative examples were measured,
The results shown in the following table were obtained. 【table】

Claims (1)

[Claims] 1. A method for producing polyamide-imide, which comprises performing a polycondensation reaction of a tribasic acid anhydride and a diisocyanate compound in the presence of a tertiary amine catalyst in a sulfolane solvent.