Thin walled polynitrile oxide crosslinked rubber film products and methods of manufacture thereof

Abstract

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.