JPH0643474B2 - Thermosetting polyamide composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-resistant synthetic resin, and particularly to a heat-resistant aromatic polyamide having a thermosetting property.

[Prior Art] As the demand of the plastics industry has become more sophisticated, industrial materials having special properties have been required, and this tendency is rapidly developing in combination with the sophistication of the technology.

The demands for improved heat resistance include plastics, films, fibers,
It is also for imparting heat resistance to industrial materials in the fields requiring heat resistance such as laminates, laminates, and adhesives to expand the market and to expand into a wide range of new fields with new functions.

In response to such demand, a group of synthetic resins called engineering plastics such as aromatic polyamide, polyimide, polysulfone, polyphenylene oxide, etc. have already been developed, and industrial production as a plastic having new functions different from conventional synthetic resins. Aromatic polyamide known under the name of aramid is one of them.

As aromatic polyamides, polyparaphenylene terephthalamide (trade name: Kepler) and polymetaphenylene isophthalamide (trade name: developed by Du Pont).
Nomex or HT-1) is a typical type.

All of these polyamides are classified as thermoplastic synthetic resins, and polyamides of the type in which an oligomer is thermoset have not been found yet.

For this reason, although it has a higher melting point than ordinary thermoplastic synthetic resins, a decrease in hardness, strength, etc. is inevitable as the temperature rises, and it is practically impossible to use above the softening point. there were.

The reason why there was no thermosetting aromatic polyamide was
It is generally considered that the melting point was sufficiently higher than that of the conventional thermoplastic synthetic resin, and that it was judged that the introduction of the unsaturated bond had a large risk of causing undesired gelation during the molding process.

[Problems to be Solved by the Invention] Aromatic polyamide is a heat-resistant polymer that is relatively stable even at a considerably high temperature, has excellent electrical properties and mechanical strength, and has high chemical stability. .

The present invention aims to further increase mechanical strength and chemical stability at high temperatures without losing these properties.

[Means for Solving the Problem] The present inventors have a relatively low melting point when molding as a molding material or a laminated plate, and can be molded into a desired shape under heating and pressurization. Research to obtain an aromatic polyamide that has sufficient heat resistance, mechanical strength, and chemical stability after curing, and can be cured under general formula A thermosetting aromatic polyamide composition was developed in which 5% by weight or less of a radical polymerization initiator was added to the aromatic polyamide oligomer represented by. It was found that this cured aromatic polyamide also possesses the above-mentioned excellent properties, and has completed the present invention.

The aromatic polyamide oligomer having a terminal unsaturated group of the present invention can be represented by the following reaction formula as an example.

In order to smoothly proceed the reaction of the above [A], a hydrogen chloride acceptor, which is a by-product, is required.
The use of primary amines or caustic is convenient.

In this case, a value of n of 1 to 15, preferably about 3 to 7, is advantageous from the viewpoint of easy moldability, and it is not particularly necessary to polymerize at this stage. In this reaction, amines are generally mixed in an aqueous phase and acid chloride is mixed with an inert organic solvent which is insoluble in water to carry out an interfacial polycondensation reaction, or both are dissolved in an inert organic solvent and condensed at a low temperature. It can be carried out by a low temperature solution polycondensation reaction.

Examples of the aromatic diamine that can be used in the present invention include metaphenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 4, 4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 4,
4'-diaminodiphenyl sulfone, dianisidine, 2,4
-Toluylenediamine, 2,4 / 2,6-toluylenediamine mixture, 1,3-bis (3-aminophenoxy) benzene and the like can be used, and a mixture of two or more kinds can also be used.

Examples of the aromatic monoamine having a terminal unsaturated group include m-
Examples thereof include isopropenylaniline, p-isopropenylaniline, o-aminostyrene, m-aminostyrene, p-aminostyrene, etc. However, it is possible to synthesize a terminal unsaturated polyamide oligomer at low temperature, stability of the produced polyamide oligomer, From the viewpoint of availability and price, m-isopropenylaniline, p-isopropenylaniline, p
-Aminostyrene is most commonly used. These amines may be free amines or hydrohalide salts, but in the case of hydrohalide salts, a tertiary amine or the like that simultaneously binds to hydrogen halide is used in combination. Is required.

Further, as the aromatic dicarboxylic acid dihalide that can be used in the present invention, a dichloride of an aromatic dibasic acid is convenient, and for example, terephthalic acid dichloride, isophthalic acid dichloride, phthalic acid dichloride or a mixture thereof is typical.

In terms of practicality, phthalic acid dichloride has insufficient heat resistance of the aromatic polyamide after curing, and when terephthalic acid dichloride is used, it has sufficient heat resistance.
The aromatic polyamide oligomer obtained has a high melting point and tends to be difficult to handle, and isophthalic acid dichloride is most suitable for the purpose of the present invention.

Since this synthetic reaction proceeds in a relatively stoichiometric manner, after calculating n in the above formula [A], the required amount of terminal unsaturated aromatic monoamine, aromatic diamine and aromatic dicarboxylic acid dihalide was calculated. The reaction can be carried out, and if precise adjustment is required, the molar ratio can be determined by a simple test.

As described above, the aromatic polyamide oligomer obtained by this reaction can be easily selected in its composition and can be molded at a temperature of 200 ° C. or lower.

The aromatic polyamide oligomer having an unsaturated terminal group synthesized by the present invention can be cured by heat curing or by using a radical generating catalyst in combination, and the heat resistance can be remarkably improved.

The radical generating catalyst does not need to be limited, but the peroxide type is industrially suitable, and the molding temperature is 1
When the temperature is 00 ° C. or higher, a so-called high-temperature decomposition type, for example, dicumyl peroxide type is used.

The amount used is 5 phr or less, preferably 1 to 3 phr.

Further, the combined use of the unsaturated bond and the copolymerizable monomer is possible when the monomer dissolves the oligomer, and particularly when the value of n in the formula [A] is small, the applicable range is wide.

The aromatic polyamide oligomer having an unsaturated terminal group in the present invention is a reinforcing agent, a filler, a release agent, and
As a matter of course, other polymers such as a colorant and a low-shrinking agent can be used in combination if necessary.

The composition thus formulated has high stability at room temperature, and it goes without saying that it is formulated immediately before use.
Storage for a short period with radical polymerization initiator
Transport is possible.

Most of the polyamide oligomers are 300 ° C.
Since it has the following melting point and has a lower viscosity than that of a usual aromatic polyamide, it can flow even in a complicated shape before being cured.

However, once it is polymerized and cured, it has no melting point or softening point, and only thermal decomposition leads to a polymer having little temperature dependence of physical properties.

Next, the following examples will be shown in order to facilitate understanding of the present invention.

[Example] (Synthesis example 1) Into a four-necked separable flask equipped with a reflux condenser, a dropping funnel, a thermometer, and a stirrer was charged 20.3 g (0.1 mol) of isophthalic acid dichloride and 100 g of dimethylformamide (DMF), and 10 ° C. Cool to:

Next, 16.67 g of 3,4'-diaminodiphenyl ether
(0.083 mol), 16.87 g of triethylamine
(0.167 mol) and 75 g of DMF are weighed and mixed, and added dropwise to a separable flask. Subsequently, 4.43 g (0.033 mol) of p-isopyropenylaniline, 3.33 g (0.033 mol) of triethylamine and 25 g of DMF are weighed and mixed, and the mixture is added dropwise to a separable flask. Meanwhile, the temperature of the reaction mixture is kept below 10 ° C. After completion of the dropping, the temperature of the reaction mixture was kept at 10 ° C. or lower for 2 hr. Continue stirring.

Then, the reaction mixture is gradually added to a large amount of water with vigorous stirring to precipitate crystals. The precipitated crystals are suction filtered, washed with water and dried.

m. p. 170-185 ° C (Synthesis example 2) Instead of 4.43 g (0.033 mol) of p-isopropenylaniline, 4.43 g of m-isopropenylaniline
The same method was used as in Synthesis Example 1 except that (0.033 mol) was used.

m. p. 170-185 ° C (Synthesis example 3) Instead of 4.43 g (0.033 mol) of p-isopropenylaniline, 3.97 g (0.0
The same procedure as in Synthesis Example 1 was performed except that 33 mol) was used.

m. p. 180-192 ° C (Synthesis example 4) 3,4'-diaminodiphenyl ether 16.67g
2,4-toluylenediamine / 2,6-toluylenediamine mixture (80:20) 1 instead of (0.083 mol)
Same as Synthesis Example 1 except that 0.17 g (0.083 mol) and p-aminostyrene 3.97 g (0.033 mol) were used instead of p-isopropenylaniline 4.43 g (0.033 mol). By the way.

m. p. 190 to 205 ° C. (Example 1) 1 part by weight of the oligomer [I] synthesized in Synthesis Example 1 and 1 part by weight of dicumyl peroxide (2% acetone solution) were added to a test tube, and the temperature was gradually raised to add acetone. It was blown dry. Then, the temperature was raised to 200 ° C. and curing was carried out for 7 hours. As a result, an amber-colored tough, insoluble and infusible bulk polymer was obtained. The obtained polymer was crushed in a mortar and dried in air for 10 minutes.
When thermogravimetric analysis was performed at a temperature rising rate of ° C / min, the result was as shown in (1) of Fig. 1.

(Example 2) 1 part by weight of the oligomer [II] synthesized in Synthesis Example 1 and 1 part by weight of dicumyl peroxide (2% acetone solution) were added to the test tube, the temperature was gradually raised, and the acetone was blown off and dried. Then, the temperature was raised to 200 ° C. and curing was carried out for 7 hours. As a result, an amber-colored tough, insoluble and infusible bulk polymer was obtained. The obtained polymer was crushed in a mortar and dried in air for 10 minutes.
When thermogravimetric analysis was carried out at a temperature rising rate of ° C / min, it became as shown in Fig. 1 (2).

(Example 3) 1 part by weight of the oligomer [III] synthesized in Synthesis Example 3 and 1 part by weight of dicumyl peroxide (2% acetone solution) were added to a test tube, the temperature was gradually raised, and the acetone was blown off and dried. Then, the temperature was raised to 200 ° C. and curing was carried out for 7 hours. As a result, an amber-colored tough, insoluble and infusible bulk polymer was obtained. The obtained polymer was crushed in a mortar and dried in air for 10 minutes.
When thermogravimetric analysis was performed at a temperature rising rate of ° C / min, the result was as shown in (3) of Fig. 1.

Example 4 1 part by weight of the oligomer [IV] synthesized in Synthesis Example 4 and 1 part by weight of dicumyl peroxide (2% acetone solution) were added to the test tube, the temperature was gradually raised, and the acetone was blown off and dried. Then, the temperature was raised to 200 ° C. and curing was carried out for 7 hours. As a result, an amber-colored tough, insoluble and infusible bulk polymer was obtained. The obtained polymer was crushed in a mortar and dried in air for 10 minutes.
When thermogravimetric analysis was performed at a temperature rising rate of ° C / min, the result was as shown in (4) of Fig. 1.

Example 5 100 parts of the oligomer [II] synthesized in Synthesis Example 2 and 2 parts of dicumyl peroxide were added to 100 parts of dimethylformamide.
After immersing the glass cloth in the solution dissolved in
A prepreg was prepared by drying at ℃ for 1 hour. After that, several prepregs were piled up and heat-press molded at a pressure of 15 kg / cm ² and a temperature of 160 ° C. for 1 hour, and then at 200 ° C. for 5 hours.
Time-cured to obtain a laminated plate. Flexural strength of the laminate is 53kg / mm ² at 25 ° C., in a 200 ° C. was 42 kg / mm ^2. The flexural strength after heating at 230 ° C. for 200 hours was 54 kg / mm ² at 25 ° C.

[Effect] Among the engineering plastics that have been developed one after another recently, there is a group of aromatic polyamides called aramids. This group has a higher melting point, higher hardness, and higher strength than conventional thermoplastic resins, and some of them have no melting point, which is extremely difficult to process and mold.
Generally, it is a thermoplastic, and it is unavoidable that the hardness and mechanical strength at high temperature decrease.

The present invention aims to develop a resin having excellent processability, hardness at high temperature, and excellent mechanical strength, which is obtained by curing an aromatic polyamide oligomer having an unsaturated group at the end of the resin. The purpose was achieved with group polyamides.

Furthermore, a composition suitable for obtaining this aromatic polyamide was developed, and the moldability of the aromatic polyamide was dramatically improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a thermogravimetric analysis diagram in air of cured resins of Examples 1, 2, 3, and 4.

Claims (1)

[Claims] 1. A general formula A thermosetting composition for aromatic polyamide, wherein 5% by weight or less of a radical polymerization initiator is added to the aromatic polyamide oligomer.