Crosslinking agent, and crosslinking polymer composition and molded product formed of the same

- Mar 08, 2019-

It is known that isocyanurate derivatives are effective as a crosslinking agent for crosslinking polymers such as crosslinking elastomers and crosslinking thermoplastic resins . In particular, among these isocyanurate derivatives, triallyl isocyanurates (hereinafter referred to merely as “TAIC”) are excellent in not only heat resistance but also chemical resistance.

However, TAIC which is in the form of a viscous liquid at an ordinary temperature tends to suffer from problems such as poor processing characteristics upon kneading, etc. For example, when kneading the TAIC with a crosslinking elastomer such as a nitrile rubber and a fluororubber using an open roll mill, there tends to arise such a problem that the kneaded material tends to suffer from roll slippage owing to sags and runs of the TAIC. In particular, when kneading the TAIC with the fluororubber having a poor compatibility with the TAIC, the roll slippage tends to be caused more remarkable, resulting in poor workability.

Also, when kneading the TAIC with the crosslinking thermoplastic resin such as polyamides and polyesters using a twin-screw extruder, it may be difficult to not only uniformly blend these components with each other but also supply the components to the extruder, resulting need of using a special supply apparatus therefor.

In particular, when kneading TAIC with the fluororubber in the applications such as semiconductors in which no filler such as carbon is incorporated into the fluororubber, it may be very difficult to supply the TAIC thereto, so that the addition time is prolonged, and the amount of the TAIC added must be limited owing to non-uniformity of the TAIC-added fluororubber, thereby causing considerable deterioration in crosslinking performance thereof. In addition, when molding the TAIC-compounded elastomer composition in a metal mold, there tend to arise problems such as contamination of the metal mold and staining of the resulting molded product (final product) owing to bleeding-out of the liquid TAIC on the surface of the molded product during the crosslinking step. Incidentally, the TAIC may be subjected to the kneading step and the crosslinking step which are carried out in separate stages from each other, in some cases. In such cases, the resulting crosslinking polymer composition in the form of a kneaded material is subjected to crosslinking reaction, for example, after preserving the composition for several days, and then formed into the final product. Under such a condition, bleeding-out of the liquid TAIC tends to be induced even during the preservation, so that the problems such as contamination of the metal mold and staining of the molded product tend to become still more remarkable.

The above conventional problems concerning the processing characteristics are one of the reasons for causing significant influences on productivity or crosslinking performance when subjecting the crosslinking elastomer or crosslinking thermoplastic resin to crosslinking reaction.