JPH0678399B2 - 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,
This is also to impart heat resistance to industrial materials in the fields requiring heat resistance such as laminates, laminated plates, and adhesives, to expand the market and to expand into a wide range of 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 intended to produce an aromatic polyamide having improved moldability without losing these excellent properties of conventional polyamides, and further improved mechanical strength and chemical stability at high temperatures. .

[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 an aromatic polyamide that has sufficient heat resistance, mechanical strength, and chemical stability after being cured. 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 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.

Maleimide or citraconic acid imide is used as a precursor of an 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, it is sufficient to calculate n in the above formula [II] and then react the required amount of maleimide, aromatic diamine and aromatic dicarboxylic acid dihalide. If a 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
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 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, maleimide 3.233 g (0.0333 mol), 3,4'-diaminodiphenyl ether (3,4'-DAPE) 16.67 g (0.0833 mol), triethylamine 20.2 g (0.2 mol) and DMF 80 g were weighed and mixed, and added dropwise to the reaction flask. To do.

After completion of the dropping, the dropping funnel is washed with 20 g of DMF, and the washing solution is added to the reaction flask. Meanwhile, the reaction temperature is kept below 10 ° C.

After completion of the dropping, stirring is continued for 2 hours while maintaining the temperature of the reaction mixture at 10 ° C or lower.

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.

<Synthesis examples 2 to 4> The operation was performed under the same conditions as in Synthesis Example 1 except that the composition was as shown in Table-1.

(Example 1) 1 part by weight of the aromatic polyamide oligomer [I] obtained in Synthesis Example 1, dicumyl peroxide (2% acetone solution) 1
Part by weight was added to a test tube, the temperature was gradually raised, and the mixture was heated at 80 ° C. for 1 hour to remove acetone and dry. Then, the temperature was raised to 160 ° C. and the temperature was raised to 200 ° C. for 2 hours, and further the temperature was raised to 200 ° C. and cured for 5 hours.

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 384 ° C 90% weight retention temperature 468 ° C Weight retention at 500 ° C 86.6% (Example 2) Aromatic polyamide oligomer [I] The aromatic compound obtained in Synthesis Example 2 instead of 1 part by weight. The same operation as in Example 1 was performed except that 1 part by weight of the polyamide oligomer [II] was used.

The obtained polymer was crushed in a mortar and subjected to thermogravimetric analysis in air at a temperature rising rate of 10 ° C./min. As a result, it became as shown in (2) of FIG.

95% weight retention temperature 315 ° C. 90% weight retention temperature 376 ° C. Weight retention at 500 ° C. 69.0% (Example 3) Aromatic polyamide synthesized in Synthesis Example 3 instead of 1 part by weight of the aromatic polyamide oligomer [I]. Polyamide oligomer [II
I] The same operation as in Example 1 was performed except that 1 part by weight was used.

The obtained polymer was pulverized in a mortar and subjected to thermogravimetric analysis in air at a temperature rising rate of 10 ° C./min. As a result, it was as shown in (3) of FIG.

95% weight retention temperature 411 ° C 90% weight retention temperature 438 ° C Weight retention at 500 ° C 71.7% (Example 4) Aromatic polyamide synthesized in Synthesis Example 4 instead of 1 part by weight of aromatic polyamide oligomer [I]. Polyamide oligomer [IV]
The same operation as in Example 1 was performed except that 1 part by weight was used.

The obtained polymer was ground in a mortar and subjected to thermogravimetric analysis in air at a temperature rising rate of 10 ° C./min.
It became like.

95% weight retention temperature 387 ° C 90% weight retention temperature 435 ° C Weight retention at 500 ° C 81.8% (Example 5) 100 parts of the oligomer [I] synthesized in Synthesis Example 1 and 2 parts of dicumyl peroxide were added to dimethyl. After immersing the glass cloth in a solution of 100 parts of formamide,
It was dried for an hour to prepare a prepreg. After that, several prepregs were superposed on each other, heat-press molded at a pressure of 30 kg / cm ² and a temperature of 160 ° C. for 1 hour, and then post-cured at 200 ° C. for 5 hours to obtain a laminate.

The bending strength of this laminate was 45 kg / mm ² at 25 ° C. The bending strength after heating at 230 ℃ for 200 hours is 25 ℃.
It was 52 Kg / mm ² .

[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 4.

Claims (1)

[Claims] 1. A general formula A composition for thermosetting polyamide, wherein a radical polymerization initiator is added to the aromatic polyamide oligomer represented by.