THIN WALLED POLYNITRILE OXIDE CROSSLINKED RUBBER FILM PRODUCTS AND METHODS OF MANUFACTURE THEREOF
Natural rubber and/or synthetic polyisoprene film products having enhanced tear strength and tensile strength crosslinked with a one polynitrile oxide, intended for direct or indirect contact with living tissue or fluids to be placed in living organisms.
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10 . A method for forming dip-molded or cast thin walled rubber film products comprised of natural rubber or synthetic cis-1,4-polyisoprene rubber crosslinked with a polynitrile oxide crosslinking agent, comprising:
(a) compounding a natural rubber or synthetic cis-1,4-polyisoprene rubber so as to substantially reduce or prevent pre-vulcanization of the resulting rubber compound;
(b) dip-molding or casting the rubber compound to form the thin-walled rubber film product;
(c) admixing the rubber compound or thin walled film product with at least one polynitrile oxide crosslinking agent; and
(d) curing the rubber compound to produce crosslinking therein.
11 . The method of claim 10 , wherein the polynitrile oxide crosslinking agent is admixed with the rubber compound in step (a).
12 . The method of claim 10 , wherein the rubber compound does not contain a sulfur-containing accelerator or nitrosatable substance.
13 . The method of claim 10 , wherein the crosslinking agent comprises mesitylene dinitrile oxide (MDNO) or 2,4,6-triethylbenzene dinitrile oxide (TON-2).
14 . The method of claim 10 , wherein the thin walled film product is formed by dip-molding a rubber latex.
15 . A method according to claim 10 wherein the rubber compound is cured at a temperature of about 150° F. or less.
16 . The method of claim 10 , wherein pre-vulcanization is substantially reduced or prevented by
(i) reducing the temperature of the compounding ingredients in step (a) to below about 25° C.; or
(ii) forming a microencapsulate containing the polynitrile oxide prior to compounding; or
(iii) compounding the latex with the polynitrile oxide immediately prior to curing; or
(iv) imbibing the polynitrile oxide into a wet or dry rubber gel; or
(v) placing the polynitrile oxide in a coagulation bath; or
(vi) curing the rubber compound by applying and curing alternating layers of the rubber and the polynitrile oxide; or
(vii) adding freshly compounded rubber to a dip-molding chamber and dipping a plurality of formers in the rubber compound and curing the rubber thereof; or
(viii) substantially reducing or eliminating a maturation period for the compounded rubber.
17 . The method of claim 16 , wherein pre-vulcanization is substantially reduced or prevented by forming a microencapsulate containing the polynitrile oxide prior to compounding.
18 . The method of claim 16 , wherein pre-vulcanization is substantially reduced or prevented by imbibing the polynitrile oxide into a wet or dry rubber gel.