JPH0662710B2 - Thermosetting aromatic polyamide and composition thereof - 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,
This is also to impart heat resistance to industrial materials in the fields where heat resistance is required, such as laminates, laminates and adhesives, to expand the market and to expand into new fields with new functions.

In response to such requirements, 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 generally have a high melting point and a small difference between the melting point and the thermal decomposition temperature, so that melt molding is difficult or impossible depending on the structure. There was a difficulty.
On the other hand, polyamides of the type in which an oligomer is heat-cured have not yet been found.

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. To obtain aromatic polyamides that can be cured under mild conditions and have sufficient heat resistance, mechanical strength, and chemical stability after curing. In addition to finding a thermosetting aromatic polyamide obtained by polymerizing the aromatic polyamide oligomer represented by, 5% by weight based on the aromatic polyamide oligomer represented by the above general formula
A thermosetting aromatic polyamide composition containing the following radical polymerization initiator was developed. It was found that this cured aromatic polyamide also has the above-mentioned excellent properties,
The present invention has been completed.

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

In order to allow the reaction of the above [II] to proceed smoothly, a hydrogen chloride acceptor, which is a by-product, is required, and it is generally convenient to use an aliphatic tertiary amine or caustic alkali.

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.

As a convenient precursor for obtaining an organic residue having an internal unsaturated group (meaning that the polymerizable unsaturated bond is inside, not at the end of the molecular chain), an organic acid halide, particularly crotonic acid chloride, Styryl acetyl chloride, β-
Styrene sulfonyl chloride, cinnamic acid chloride, sorbic acid chloride and the like can be mentioned, but crotonic acid chloride is most commonly used in terms of availability and price.

Hereinafter, the organic acid halide having an internal unsaturated group will be described by using crotonic acid chloride as a representative.

As the aromatic dicarboxylic acid dihalide that can be used in the present invention, a dichloride of an aromatic dibasic acid is convenient, and representative examples thereof include terephthalic acid dichloride, isophthalic acid dichloride, phthalic acid dichloride and a mixture thereof.

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 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 [II], necessary amounts of internal unsaturated organic acid halide, aromatic diamine and aromatic dicarboxylic acid dihalide were 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 internal unsaturated terminal group synthesized according to the present invention can be cured by the combined use of a radical generating catalyst, and the heat resistance can be markedly 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 monomer capable of being copolymerized with the internal unsaturated bond is possible when the monomer dissolves the oligomer, and particularly when the value of n in the formula [I] is small, the applicable range thereof is wide.

In the present invention, the aromatic polyamide oligomer having an internal unsaturated terminal group can, of course, be used in combination with a reinforcing agent, a filler, a release agent, a colorant, another polymer as a low-shrinking agent and the like, 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, in order to help understanding of the present invention, examples will be shown below.

[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 16.92 g (0.083 mol) of isophthalic acid dichloride and 100 g of dimethylformamide (DMF) at 10 ° C. Cool to:

Next, 3,4'-diaminodiphenyl ether (3,4'-DA
PE) 20 g (0.1 mol), triethylamine 20.
2 g (0.2 mol) and 75 g of DMF are weighed and mixed and added dropwise to a separable flask. Subsequently, 3.483 g (0.033 mol) of crotonic acid chloride and 25 g of DMF are weighed and mixed, and added dropwise to a separable flask. in the meantime,
The temperature of the reaction mixture is kept below 10 ° C. After the completion of 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. 165-180 ° C (Synthesis example 2) Isophthalic acid chloride 10.15 g (0.05 mol), 3,3'-diaminodiphenyl sulfone 16.53
g (0.067 mol), triethylamine 13.6 g
(0.135 mol), crotonic acid chloride 3.483
The same operation as in Synthesis Example 1 was performed except that g (0.033 mol) was used.

m. p. 145-160 ° C (Synthesis example 3) Isophthalic acid chloride 10.15 g (0.05 mol), mixed toluylenediamine (2,4'-toluylenediamine / 2,6-toluylenediamine [80:20]) 6.7
8 g (0.056 mol), triethylamine 20.2 g
(0.2 mol), 10.45 g of crotonic acid chloride
The same operation as in Synthesis Example 1 was performed except that (0.1 mol) was used.

m. p. 170 to 185 ° 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. Flyed 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,
It became like (1) in the figure.

(Example 2) 1 part by weight of the aromatic polyamide oligomer [II] obtained in Synthesis Example 2 and dicumyl peroxide (2% acetone solution) 1
Part by weight was added to the test tube, the temperature was gradually raised, the acetone was blown off, and the test tube was 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 is crushed in a mortar,
When thermogravimetric analysis was performed in air at a temperature rising rate of 10 ° C./min, the result was as shown in (2) of FIG.

(Example 3) Aromatic polyamide oligomer [III] 1 obtained in Synthesis Example 3
Parts by weight, dicumyl peroxide (2% acetone solution)
1 part by weight was added to the test tube, the temperature was gradually raised, the acetone was blown off, and the test tube was 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 pulverized in a mortar and subjected to thermogravimetric analysis in air at a temperature rising rate of 10 ° C./min, and the result was as shown in (3) of FIG.

(Example 4) 100 parts of the oligomer [I] synthesized in Synthesis Example 1 and 2 parts of dicumyl peroxide were mixed with 10 parts of dimethylformamide.
After immersing the glass cloth in the solution dissolved in 0 part, 12
A prepreg was prepared by drying at 0 ° C for 1 hour. After that,
After stacking several prepregs and heat and pressure molding at a pressure of 15 kg / cm ² and a temperature of 160 ° C for 1 hour, 200 ° C, 5
Time-cured to obtain a laminated plate.

The flexural strength of this laminate was 45 kg / mm ² at 25 ° C. The flexural strength after heating at 230 ° C. for 200 hours was 53 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 decrease at high temperatures.

The present invention aims to develop a resin having excellent processability, hardness at high temperature, and excellent mechanical strength. A thermosetting aromatic compound obtained by using an aromatic polyamide oligomer having an internal unsaturated group The purpose was achieved with polyamide.

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

[Brief description of drawings]

FIG. 1 shows the results of thermogravimetric analysis of the polymers obtained in Examples 1 to 3.

Claims (2)

[Claims] 1. A general formula A composition for a thermosetting resin, which comprises an aromatic polyamide oligomer represented by the formula (b) and a radical polymerization initiator (b). 2. In the general formula [I], A and A'are C
The thermosetting resin composition according to claim 1, wherein H ₃ CH = CH-, B and B'are aromatic polyamide oligomers represented by -CO-.