Tack free surface cures of polymers by organic peroxides in the presence of air

Abstract

Compositions are disclosed which comprise mixtures of at least one compound selected from silicone elastomers, bis-, tri- or higher polymaleimides and/or bis-, tri- or higher polyciraconimides, and at least one compound selected from p-phenylene-diamine based antiozonants, sulfur compounds capable of accelerating sulfur vulcanization of polymers capable of being crosslinked by sulfur and polysulfide polymers which when compounded into polymers curable by free radical initiators in the presence of free radical initiators permit substantially tack free surface cure of the polymers by decomposition of the free radical initiator in the presence of molecular oxygen. Compositions containing the above ingredients and at least one free radical initiator, curable compositions containing the combination and processes for making and using the compositions are also disclosed.

We claim:  
     
         1 . A composition comprising: 
 a) At least one compound (A) selected from the group consisting of silcone elastomers and a compound having the formula (I):                          Wherein n is 1, or 2 and R is divalent, or trivalent and is selected from the group consisting of acyclic aliphatic groups having from about 2 to 16 carbon atoms, cyclic aliphatic groups having from about 5 to 20 carbon atoms, aromatic groups having from about 6 to 18 carbon atoms and allyl aromatic groups having from about 7 to 24 carbon atoms, and wherein the divalent, or trivalent groups may contain one or more heteroatoms selected from O, N and S, replacing a carbon atom, or carbon atoms and each R 1  is identical and is hydrogen or an alkyl group of 1 to 18 carbon atoms; and    b) At least one compound (B) selected from the group consisting of p-phenylenediamine based antiozonants and sulfur containing organic compounds selected from the group consisting of sulfur containing organic compounds capable of accelerating sulfur vulcanization of a polymer capable of being crosslinked by sulfur, polysulfide polymers and mixtures of said sulfur containing compounds.    
     
     
         2 . A composition as defined in  claim 1  additionally containing a free radical initiator selected from the group consisting of organic peroxides and azo initiators.  
     
     
         3 . A composition comprising a composition as deemed in  claim 2  and a polymer curable by free radical initiators.  
     
     
         4 . A process comprising forming the composition of  claim 3  into a shaped article and then subjecting it in the presence of molecular oxygen to a temperature sufficient to initiate decomposition of the free radical initiator and thereby obtaining a cured shaped article substantially free of surface tack.  
     
     
         5 . A composition formed by mixing compounds (A) and (B) as defined in claim one.  
     
     
         6 . A composition formed by mixing compounds (A) and (B) as defined in  claim 1  and an organic peroxide in any order.  
     
     
         7 . A composition as defined in  claim 1  wherein compound (A) is selected from bismaleimides and Compound (B) is selected from sulfur accelerators.  
     
     
         8 . A composition as defined in  claim 1  wherein compound (A) is selected from biscitraconimides and compound (B) is selected from sulfur accelerators.  
     
     
         9 . A composition as defined in  claim 1  wherein compound (A) is selected firm bismaleimides and compound (B) is selected from polysulfide polymers.  
     
     
         10 . A composition as defined in  claim 1  wherein compound (A) is selected from biscitraconimides and compound (B) is selected from polysulfide polymers.  
     
     
         11 . A composition as defined in  claim 1  wherein compound (A) is selected from silicone elastomers and compound (B) is selected from polysulfide polymers.  
     
     
         12 . A composition as defined in  claim 1  also comprising a compound selected from the group consisting of chlorinated polyethylene and chlorosulfonated polyethylene.  
     
     
         13 . A composition as defined in  claim 2  wherein the free radical initiator is selected from organic peroxides.  
     
     
         14 . A surface tack free cured polymer cured in the presence of molecular oxygen by free radicals generated by decomposition of the free radical initiator in a composition as defined in  claim 3 .  
     
     
         15 . A process for making a surface tack free cured polymer cured by free radicals generated by decomposition of a free radical initiator contained therein in the presence of molecular oxygen which comprises compounding said polymer with a composition as defined in  claim 2  and supplying sufficient heat energy to decompose the free radical initiator thus introduced into the polymer.  
     
     
         16 . A process for making a curable composition capable of being cured to a tack free surface in the presence of molecular oxygen by a free radical initiator which process comprises compounding a polymer capable of being crosslinked by a free radical initiator with a composition as defined in  claim 2 .  
     
     
         17 . A process for making a curable composition capable of being cured to a tack free surface in the presence of molecular oxygen by a free radical initiator which comprises compounding a polymer capable of being crosslinked by a free radical initiator containing a composition as defined in  claim 1  in the presence of a free radical initiator.  
     
     
         18 . A composition as defined in  claim 1  wherein compound (A) is selected from one or more bismaleimides and compound (B) is selected from the group consisting of dialkylthiuram tetrasulfides diarylthiuram tetrasulfides, alkylphenol disulfides, tetraalkylthiuram monosulfides, tetraalkylthiuram monosulfides and mixtures thereof.  
     
     
         19 . A composition as defined in  claim 2  wherein the free radical initiator is selected from dialkyl peroxides or peroxyketals.  
     
     
         20 . A composition as defined in  claim 18  additionally containing a free radical initiator selected from dialkyl peroxides or peroxyketals.  
     
     
         21 . A composition as defined in  claim 1  wherein compound (A) is selected from one or more bismaleimides and compound (B) is selected from the group consisting of 4,4-dithiomorpholine, acyclicalkyl-2-benzothiazole sulfenane, cyclicalky-2-benzothiazole sulfenamides, aryl-2-benzothiazole sulfenamides, alkylphenol disulfides and mixtures thereof.  
     
     
         22 . A composition as defined in  claim 21  additionally containing a free radical initiator selected from dialkyl peroxides, or peroxyketals.  
     
     
         23 . A composition as defined in  claim 2  comprising dicumylperoxide, N,N-phenylenebismaleimide, 4,4-dithiomoropholine, alkylphenoldisulfide and N-cyclohexyl-2-benzothiazole sulfenamide.  
     
     
         24 . A composition as defined in  claim 2  comprising dicumylperoxide, N,N-phenylenebismaleimide, dipentamethylene thiuram tetrasulfide, alkylphenoldisulfide, and tetramethylthiuram monosulfide.  
     
     
         25 . A composition as defined in  claim 2  comprising dicumyl peroxide, N,N-phenylenebismaleimide, dipentamethylenethiuram is tetrasulfide, alkylphenol disulfide and N-t-butyl-benzothiazole-2-sulfenimide.  
     
     
         26 . A composition as defined in  claim 1  formulated as a masterbatch on a carrier selected from the group consisting of microcrystalline wax, polycaprolactone, EPDM, EPM, EVA, PE and mixtures thereof.  
     
     
         27 . A composition as defined in  claim 2  formulated as a masterbatch on a carrier selected from microcrystalline wax, polycaprolactone, EPDM, EPM, EVA, PE and mixtures thereof.