JPH0662723B2 - Thermosetting polyamide and composition thereof - Google Patents

Description

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

[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, laminated plates and adhesives, for expanding the market and for expanding 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 essentially classified as thermoplastic synthetic resins, but generally have a high melting point, and some have a small difference between the melting point and the thermal decomposition temperature or they are reversed. Therefore, there is a problem that melt molding is difficult or impossible depending on the structure. On the other hand, polyamides of the type that prepares an oligomer as a precursor and heat-cures it have not been proposed yet.

The reason why there was no thermosetting aromatic polyamide was
It is considered that its melting point was generally sufficiently higher than that of conventional thermoplastic synthetic resins, and that it was judged that the introduction of unsaturated bonds had a large risk of causing undesirable 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 is directed to the production of aromatic polyamides which have improved molding processability without losing the excellent properties of conventional polyamides, and have improved mechanical strength and chemical stability at high temperatures.

[Means for Solving the Problems] The inventors of the present invention have a relatively low melting point and can form a desired shape under heating and pressurization as a molding material or in the case of systematic processing as a laminated plate, Moreover, research was conducted to obtain an aromatic polyamide that can be cured under relatively mild conditions and that has 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 polyamide composition containing the following radical polymerization initiator was developed. This cured aromatic polyamide has the excellent chemical and mechanical properties of conventional aromatic polyamides, as well as the excellent characteristics of easy molding and less deterioration of mechanical strength at high temperature. The present invention has been completed and the present invention has been completed.

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 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 in terms of 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 solvent which does not dissolve 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.

Acrylamide and methacrylamide are used as precursors of the organic residue having a terminal unsaturated group.

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.

The heat resistance of the aromatic polyamide derived from phthalic acid dichloride is a little insufficient, and the heat resistance of the polymer after thermosetting is sufficient when terephthalic acid dichloride is used, but the aromatic compound used as a precursor. Since the melting point of the group polyamide oligomer tends to be high and handling tends to be difficult, isophthalic acid dichloride has the best balanced property from a practical viewpoint, which is consistent with the object of the present invention.

Since this synthetic reaction proceeds relatively stoichiometrically, after calculating n in the above formula [II], the required amount of (meta)
It is sufficient to react acrylamide, aromatic diamine and aromatic dicarboxylic acid dihalide, and if precise adjustment is required, the molar ratio can be determined by a simple test.

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

The aromatic polyamide oligomer having a terminal unsaturated 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.

It is not necessary to limit the radical generation catalyst, but industrially the peroxide type is suitable and the molding temperature is 10
When the temperature is 0 ° 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 of the aromatic polyamide oligomer and the copolymerizable monomer is possible when the monomer dissolves the oligomer, and particularly when the value of n in the formula [I] is a small value, the applicable range is wide.

The aromatic polyamide oligomer having a terminal unsaturated group in the present invention is a reinforcing agent, a filler, a release agent, and
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 have a melting point of 300 ° C. or lower, and have a low viscosity as compared with ordinary aromatic polyamides, so that they can flow even in a complicated shape before curing.

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) 500 ml equipped with reflux condenser, dropping funnel, thermometer, stirrer
In a 4-neck separable flask, 20.3 g (0.1 mol) of isophthalic acid chloride and 1 dimethylformamide (DMF)
Charge 00g and cool to below 10 ℃.

Next, a predetermined amount (0.0333 mol) of acrylamide or methacrylamide, a predetermined amount (0.0833 mol) of aromatic diamine, 20.2 g (0.2 mol) of toluethylamine, and 100 g (or 80 g) of DMF are weighed and mixed, and added dropwise to the reaction flask. 〔D
When MF80g is used, the dropping funnel is washed with DMF20g after completion of the dropping, and the washing solution is dropped into the reaction flask. Meanwhile, the reaction temperature is kept at 10 ° C. or lower.

After the completion of dropping, keep the temperature of the reaction mixture at 10 ° C or lower for 2 hours.
Continue stirring.

Next, 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.

(Example 1) 1 part by weight of the oligomer [I] obtained in Synthesis Example 1 and 1 part by weight of dicumyl peroxide (2% acetone solution) were added to a test tube, the temperature was gradually raised, and acetone was blown off to dry. next
When the temperature was raised to 200 ° C. and curing was carried out for 7 hours, a solid, insoluble and infusible bulk polymer having an amber color was obtained. The obtained polymer was crushed 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 (1) of FIG.

95% weight retention temperature 304 ° C 90% weight retention temperature 423 ° C 500 ° C weight retention 74.4% (Example 2) Instead of the oligomer [I] synthesized in Synthesis Example 1, an oligomer [II synthesized in Synthesis Example 2 was used. Example 1 except that
The same operation was performed.

The thermogravimetric analysis of the obtained polymer gave the result shown in (2) of FIG.

95% weight retention temperature 305 ° C 90% weight retention temperature 387 ° C 500 ° C weight retention 72.3% (Example 3) Instead of the oligomer [I] synthesized in Synthesis Example 1, an oligomer [III synthesized in Synthesis Example 3 was used. ] The same operation as in Example 1 was performed except that

Thermogravimetric analysis of the obtained polymer shows that (3) in FIG.
It became like.

95% weight retention rate temperature 317 ° C. 90% weight retention rate temperature 408 ° C. 500 ° C. weight retention rate 72.0% (Example 4) Instead of the oligomer [I] synthesized in Synthesis Example 1, an oligomer [IV synthesized in Synthesis Example 4 was used. Example 1 except that
The same operation was performed.

Thermogravimetric analysis of the obtained polymer gave the following results.

95% weight retention temperature 323 ° C 90% weight retention temperature 426 ° C 500 ° C weight retention 73.5% (Example 5) Instead of the oligomer [I] synthesized in Synthesis Example 1, an oligomer [V synthesized in Synthesis Example 5 was used. Example 1 except that
The same operation was performed.

Thermogravimetric analysis of the obtained polymer gave the following results.

95% weight retention temperature 301 ° C 90% weight retention temperature 418 ° C 500 ° C weight retention 73.8% (Example 6) 100 parts of the oligomer [I] synthesized in Synthesis Example 1 and 2 parts of dicumyl peroxide were added to dimethylform. A glass cloth was immersed in a solution prepared by dissolving 100 parts of amide and then dried at 100 ° C. for 1 hour to prepare a prepreg. After that, several prepregs were piled up, pressure 15Kg / cm ² , temperature 180 ℃
After heat-press molding for 1 hour, the mixture was cured at 200 ° C. for 5 hours to obtain a laminated plate.

The bending strength of this laminate was 43 Kg / mm ² at 25 ° C. The bending strength after heating at 230 ° C. for 200 hours was 4 kg / mm ² at 25 ° C.

[Effects] Among the engineering plastics that have been developed one after another, 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.
The essence is a thermoplastic, and it is unavoidable that the hardness and mechanical strength decrease at high temperatures.

The present invention is researched for the purpose of developing a heat-resistant 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 terminal. The object was achieved by developing a thermosetting aromatic 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 (1)

[Claims] 1. A general formula [I] A composition for thermosetting polyamide resin, which comprises an aromatic polyamide oligomer represented by the formula (2) and a radical polymerization initiator (b).