JPS646225B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel polyimide resin, and more particularly to a polyimide resin soluble in organic polar solvents, particularly an aromatic polyimide resin soluble in organic polar solvents. It is already known that polyimide polymers have excellent properties such as heat resistance and chemical resistance, and are particularly useful for applications such as wire coatings, films, and adhesives that are used at high temperatures. Very useful. Conventionally known polyimide polymers that have important coating film-forming properties for film and wire coating applications are usually prepared by mixing aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent. High molecular weight polyamic acids subjected to addition reaction at low temperatures are known. Polyimide is generally insoluble in solvents and is difficult to melt-mold. Therefore, after the polyamic acid is molded, it is dehydrated and ring-closed by a method such as heating, and then used as polyimide.
Although this polyamic acid has excellent heat resistance, it has poor stability during storage, and has the disadvantage that it must be stored at low temperatures because it increases viscosity and gels even at room temperature. In addition, in polymerization to obtain such a polyamic acid, the polymerization solvent must be completely dehydrated in order to obtain a high molecular weight polyamic acid, and the tetracarboxylic dianhydride used must be dried by heating for a long time. It has the disadvantage that it must be Another inherent problem is that the polyamic acid is dehydrated and ring-closed after being formed into wire coatings and films, resulting in poor workability during processing. As a manufacturing method and a processing method for imide-based polymers that do not have these drawbacks and problems, first, a high molecular weight solvent-soluble ring-closed polyimide is synthesized, and the solvent is removed from this polyimide solution. One possible method is to obtain an imide polymer or a molded article thereof. Based on this idea, the present inventors conducted research and found that a diamine with a specific structure and an organic tetracarboxylic acid or its acid anhydride were mixed in an organic solvent under certain conditions. It was discovered that a polyimide resin soluble in an organic polar solvent, which has excellent coating film-forming ability, is produced by reaction, and the present invention was achieved based on this discovery. The present invention relates to a novel polyimide resin, particularly a novel aromatic polyimide resin, which is soluble in organic polar solvents and has the following chemical structural formula. (In the formula, R is

[Formula] or

A tetravalent organic group consisting of [Formula], where n is m-cresol or methylpyrrolidone.
As a 20% solution by weight, the solution viscosity at 20℃ is 1000~
This number indicates 50000cps. ) In the present invention, isophorone structure

Although a diamine or diisocyanate having the formula is used, the decrease in heat resistance is smaller than when using a generally known aliphatic diamine or diisocyanate.
The resulting polyimide resin is treated with an organic polar solvent, especially
It is possible to make it soluble in cresol solvents. The polyimide resin having the above chemical structural formula of the present invention comprises an organic tetracarboxylic acid or a functional derivative thereof and isophorone diamine (3-
aminomethyl-3,5,5-trimethylcyclohexyl-amine). The polyimide resin having the above chemical structural formula can be obtained by reacting an organic tetracarboxylic acid or its anhydride with isophorone diisocyanate (3-isocyanatomethyl-3,5,5-trimethylcyclohexyl-isocyanate) having the following chemical structural formula. . Examples of organic tetracarboxylic acids include pyromellitic acid, benzophenonetetracarboxylic acid, 1,2,
5,6-naphthalenetetracarboxylic acid, 2,3,
6,7-naphthalenetetracarboxylic acid, 1,2,
Examples include 3,4-butanetetracarboxylic acid and tetrahydrofurantetracarboxylic acid. From the viewpoint of heat resistance, aromatic tetracarboxylic acids are desirable. Derivatives other than the above-mentioned tetracarboxylic acids having similar functions include their dianhydrides, monoanhydrides, esters, amides, etc., but it is preferable to use tetracarboxylic anhydrides. It is better to do so. Furthermore, by replacing a part of isophorone diamine and isophorone diisocyanate with aromatic diamine, diisocyanate, or aliphatic diamine and diisocyanate, "heat resistance" and "flexibility" can be improved. Examples of these compounds include 4,4'-diaminodiphenylpropane,
4,4'-diaminodiphenyl ether, diphenylmethane diisocyanate, diphenyl ether diisocyanate, hexamethylene diamine,
2,4,4 trimethylhexamethylene diamine,
Examples include hexamethylene diisocyanate, 2,4,4 trimethylhexamethylene diisocyanate, and the like. The polyimide polymerization reaction of the present invention is preferably carried out in the presence of a chemically inert organic polar solvent, such as N-methylpyrrolidone, dimethylacetamide, dimethylformamide, dimethylsulfoxide, dimethylsulfone, N-methylcarbon Prolautum, resolic acid, P-cresol, m-
Cresol etc. can be used. Generally, cresol solvents are inexpensive compared to other polar solvents, so it is desirable to use cresol solvents from an industrial perspective. Furthermore, mixtures of the above solvents and mixtures of the above solvents with small amounts of toluene, xylene, ethylbenzene, etc. can also be used. The molar ratio of organic tetracarboxylic acid or its derivative having a similar function to isophorone diamine or isophorone diisocyanate is:
This mole is desirable. However, even if there is a slight excess of either, it is possible to carry out polymerization by selecting specific conditions such as temperature, type and amount of catalyst, and pressure. Polymerization temperature is 50℃ to 300℃, preferably 100℃ to 250℃
It is preferable to choose a temperature range of °C. The polyimide resin of the present invention is soluble in organic polar solvents, particularly cresol solvents, and in particular cresol solvents, and if a cresol solvent is used as a reaction solvent, it can be used as a solution for coil impregnation varnish, wire enamel, varnish cloth, etc. Used as electrical insulating varnish. Furthermore, a film with excellent heat resistance and mechanical strength can be produced from the resin solution, and can be used in various applied fields. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. Example 1 21.8 g (0.1 mol) of pyromellitic dianhydride and 117 ml of m-cresol were placed in a 500 ml four-necked flask equipped with a stirrer, thermometer, cooling tube, and nitrogen gas inlet tube.
was added and dissolved. Next, 17.0 g (0.1 mol) of isophoronediamine was added and the temperature was raised to 160°C, which increased the viscosity while distilling the produced water. After distilling about 3.6g of water in 1 hour, after heating at 200℃ for 3 hours, m-
Diluted by adding cresol. The obtained solution is
It was a clear, pale yellow, viscous solution, and the solution viscosity was measured at 20°C and was 28,000 cps (12% by weight solution). Next, when we measured the infrared spectrum of the resin produced, it showed a spectrum as shown in Figure 1, especially at 1770 cm ^-1 and 1700 to 1720 cm -1, which are the characteristic absorption bands of imide rings.
It showed remarkable absorption in cm ^-1 and was confirmed to have an almost completely ring-closed polyimide structure as shown in the formula below. Apply this resin solution on a glass plate and apply 100 to 150
A casting film was prepared by raising the temperature to ℃ over 30 minutes. The obtained film was a pale yellow transparent film. Next, heat this film to 190℃.
A heat resistance test was conducted after leaving the sample in an atmosphere of ~280°C for 30 minutes. When the prepared film was immersed in a 260°C solder bath for 3 seconds, no change was observed and it showed the expected heat resistance. Example 2 Using the same equipment and method as in Example 1, 32.2 g (0.1 mol) of benzophenonetetracarboxylic dianhydride and 148 ml of m-cresol were added and dissolved, and then 17.0 g (0.1 mol) of isophoronediamine was added. and heated. When the temperature reached 160°C, the viscosity increased while distilling the produced water. After distilling off about 3.6 g of water in 1 hour, the mixture was further heated at 200°C for 6 hours, and then diluted with m-cresol. The obtained solution was a dark red viscous solution, and the solution viscosity was measured at 20°C.
It was 6800 cps (20% by weight solution). Next, when we measured the infrared spectrum of the resin produced, we found that it had a characteristic absorption band of imide rings at 1770 cm.
It was confirmed that it had a nearly completely ring-closed polyimide structure as shown in the formula below, showing remarkable absorption at ^-1 1700 to 1720 cm ^-1 . Example 3 10.9 g (0.05 mol) of pyromellitic anhydride instead of 21.8 g (0.1 mol) of pyromellitic anhydride
Benzophenonetetracarboxylic dianhydride 16.1
Polymerization was carried out using the same apparatus and method as in Example 1, except that 0.05 g (0.05 mol) was used. The obtained resin solution was a transparent red viscous solution, and when the viscosity was measured at 20℃, it was 13000 cps (20
wt% solution). As a result of measuring the infrared spectrum, Examples 1 and 2
Similar to the spectrum of , there is absorption in the characteristic absorption band of imide, confirming that it has an almost completely ring-closed polyimide structure. Example 4 Using the same equipment and method as in Example 1, m-
120 ml of cresol was added and dissolved. Next, 23.1 g (0.104 mol) of isophorone diisocyanate was added,
The mixture was heated and stirred at 140°C to 160°C for 2 hours and at 200°C for 8 hours. The resulting solution is a dark red viscous solution at 20°C.
When the viscosity was measured, it was 2000 cps (25% by weight). When the infrared spectrum of the obtained resin was measured, it showed the same infrared spectrum as the resin obtained in Example 1, which confirmed that it had a substantially ring-closed polyimide structure that was the same as that of Example 1. It was done. Example 5 Using the same equipment and method as in Example 4, 21.8 g (0.1 mol) of pyromellitic anhydride and anhydrous N-methyl-
127 g of 2-pyrrolidone was added and dissolved. Next, 22.2g (0.1mol) of isophorone diisocyanate
The mixture was added dropwise over 2 hours while heating and stirring at 140°C. When the temperature was further raised to 200°C and the reaction was continued for 4 hours, a dark red viscous solution was obtained. From the infrared spectrum of this resin, it was confirmed that it had the same nearly ring-closed polyimide structure as the resin of Example 1. Example 6 Using the same equipment and method as in Example 1, 25.4 g (0.1 mol) of pyromellitic acid was used instead of pyromellitic anhydride, and 148 ml of m-cresol was added and dissolved, followed by 17.0 g (0.1 mol) of isophoronediamine.
was added and heated. When the temperature reached 160°C, the viscosity increased while distilling the produced water. Approximately 7.2g in 1 hour
After distilling off the water, after further heating at 200℃ for 6 hours,
It was diluted by adding m-cresol. The obtained solution was a dark red viscous solution, and the solution viscosity was measured at 20°C and was 7200 cps (20% by weight solution). As a result of measuring the infrared spectrum, Examples 1 and 2
Similar to the spectrum of , there is absorption in the characteristic absorption band of imide, confirming that it has an almost completely ring-closed polyimide structure.

[Brief explanation of drawings]

Figure 1 shows the infrared absorption spectrum of the resin obtained in Example 1.

Claims (1)

[Scope of Claims] 1. A novel polyimide resin soluble in organic polar solvents and having the following chemical structural formula (1). (In the formula, R is [formula] or a tetravalent organic group consisting of [formula], and n is m-cresol or methylpyrrolidone.
20% solution by weight, solution viscosity at 20℃ is 1000~
This number indicates 50000cps. )