Rubbery Polymer WIth Low Compression Set

Abstract

A rubbery polymer comprising: (a) butyl acrylate or a mixture of butyl acrylate and 2-ethylhexyl acrylate, (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a half ester maleate soap, and (f) a crosslinking agent selected from allyl methacrylate, and mixtures of allyl methacrylate with glycidyl methacrylate, trimethylolpropanetrimethyl acrylate, dicyclopentenyloxyethyl methacrylate and divinylbenzene.

1 . A rubbery polymer, which can be blended with a thermoplastic resin, comprising:
 (a) butyl acrylate or a mixture of butyl acrylate and 2-ethylhexyl acrylate,   (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate,   (c) acrylonitrile,   (d) styrene,   (e) a half ester maleate soap, and   (f) a crosslinking agent selected from allyl methacrylate, glycidyl methacrylate, trimethylolpropanetrimethyl acrylate, dicyclopentenyloxyethyl methacrylate, divinylbenzene, and mixtures thereof,   
       wherein said rubbery polymer is obtainable by a process comprising the steps of:
 (I) polymerizing monomers selected from (a) to (f) as defined above under emulsion polymerization conditions to produce an elastomeric seed polymer containing latex, allyl methacrylate being necessarily present, 
 (II) adding additional monomers selected from (a) to (f) as defined above to the elastomeric seed polymer containing latex under emulsion polymerization conditions, 
 (III) recovering the rubbery polymer from the emulsion containing the rubbery polymer. 
 
     
     
         2 . A rubbery polymer according to  claim 1 , wherein step (I) comprises polymerizing the monomers (a), (b), (c), (e) and (f), allyl methacrylate being necessarily present, and step (II) comprises adding additional monomer (c), the monomer (d) and additional monomer (f), (a) to (f) being as defined in  claim 1 . 
     
     
         3 . A rubbery polymer according to  claim 1 , comprising:
 (a) from 40 to 80 weight percent butyl acrylate or from 40 to 80 weight percent of a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 weight percent 2-ethylhexyl acrylate,   (b) from 1 to 35 weight percent of a member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate,   (c) from 4 to 30 weight percent acrylonitrile,   (d) from 3 to 25 weight percent styrene, and   (e) from 0.5 to 8 weight percent half ester maleate soap, and   (f) from 0.2 to 8 weight percent crosslinking agent selected from allyl methacrylate and mixtures of allyl methacrylate with glycidyl methacrylate, trimethylolpropanetrimethyl acrylate, dicyclopentenyloxyethyl methacrylate, and divinylbenzene.   
     
     
         4 . A rubbery polymer according to  claim 1 , comprising:
 (a) from 50 to 80 weight percent butyl acrylate, or from 50 to 80 weight percent of a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 weight percent of 2-ethylhexyl acrylate,   (b) from 1 to 25 weight percent of a member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate,   (c) from 6 to 30 weight percent acrylonitrile,   (d) from 5 to 18 weight percent styrene, and   (e) from 1 to 5 weight percent half ester maleate soap, and   (f) from 0.25 to 4 weight percent of crosslinking agent selected from allyl methacrylate and mixtures of allyl methacrylate with glycidyl methacrylate, trimethylolpropanetrimethyl acrylate, dicyclopentenyloxyethyl methacrylate, divinylbenzene.   
     
     
         5 . A rubbery polymer according to  claim 1 , comprising:
 (a) from 55 weight percent to 75 weight percent butyl acrylate, or a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40 weight percent of 2-ethylhexyl acrylate,   (b) from 1 weight percent to 20 weight percent of at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate,   (c) from 10 weight percent to 25 weight percent acrylonitrile,   (d) from 8 weight percent to 14 weight percent styrene,   (e) from 2 weight percent to 4 weight percent of a half ester maleate soap, and   (f) from 0.25 weight percent to 3 weight percent of a crosslinking agent selected from allyl methacrylate, and mixtures of allyl methacrylate with glycidyl methacrylate, trimethylolpropanetrimethyl acrylate, dicyclopentenyloxyethyl methacrylate, divinylbenzene.   
     
     
         6 . A rubbery polymer according to  claim 1  wherein the crosslinking agent is allyl methacrylate. 
     
     
         7 . A rubbery polymer according to  claim 6  containing 0.25 to 3 weight percent, preferably around 0.5 weight percent of allyl methacrylate. 
     
     
         8 . A polymeric composition which is a blend comprising at least one thermoplastic resin and a rubbery polymer according to anyone of the preceding claims. 
     
     
         9 . A polymeric composition according to  claim 8 , further comprising an ingredient selected from plasticizers, antioxidants, fillers, colorants, pigments and mixture thereof. 
     
     
         10 . A polymeric composition according to  claim 8  or  9 , wherein the thermoplastic resin is PVC. 
     
     
         11 . A gasket with low compression set comprised of a polymeric composition according to anyone of  claims 8  to  10 . 
     
     
         12 . A method for preparing a rubbery polymer according to  claim 1 , comprising the steps of:
 (I) polymerizing monomers selected from (a) to (f) as defined in  claim 1  under emulsion polymerization conditions to produce an elastomeric seed polymer containing latex, allyl methacrylate being necessarily present,   (II) adding additional monomers selected from (a) to (f) to the elastomeric seed polymer containing latex under emulsion polymerization conditions,   (III) recovering the rubbery polymer from the emulsion containing the rubbery polymer.   
     
     
         13 . A method according to  claim 12 , wherein step (I) comprises polymerizing the monomers (a), (b), (c), (e) and (f), as defined in  claim 1 , allyl methacrylate being necessarily present, and step (II) comprises adding additional monomer (c), the monomer (d) and additional monomer (f).