Conjugated diene/monovinylarene block copolymers blends

Abstract

This invention relates to polymer blends, which comprise at least one tapered conjugated diene-monovinylarene block copolymer and at least one styrenic polymer. The polymer blends possess good optical and mechanical properties.

What is claimed:  
     
         1 . A polymer blend comprising at least one coupled conjugated diene/monovinylarene block copolymer and at least one styrenic polymer, wherein 
 the coupled conjugated diene/monovinylarene block copolymer is produced by a process comprising sequentially contacting under polymerization conditions at least one monovinylarene monomer, an organoalkali metal initiator, at least one conjugated diene monomer, and thereafter coupling with a polyfunctional coupling agent to form the block copolymer;    at least three consecutive monomer mixture charges containing monovinylarene monomer and conjugated diene monomer are provided to produce at least three consecutive conjugated diene/monovinylarene tapered blocks in the block copolymer;    all the monovinylarene monomer and conjugated diene monomer contained in each charge are added at the beginning of the charge allowing excess of monomer to be present in the reactor;    the at least one monovinylarene monomer contains from 8 to 18 carbon atoms, and the at least one conjugated diene monomer contains from 4 to 12 carbon atoms, and    the styrenic polymer is selected from the group consisting of at least one copolymer produced by copolymerizing at least one styrenic co-monomer and at least one unsaturated oxygen or nitrogen containing co-monomer.    
     
     
         2 . The polymer blend of  claim 1  comprising 
 (A) 50 wt % or less of the styrenic polymer; and  
 (B) 50 wt % or more of the coupled conjugated diene/monovinylarene block copolymer.  
 
     
     
         3 . The polymer blend of  claim 2 , wherein 
 the monovinylarene monomer is selected from the group consisting of styrene, 2-methylstyrene 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, α-methylstyrene, and mixtures thereof; and    the conjugated diene monomer is selected from butadiene, isoprene, 2,3-dimethylbutadiene.    
     
     
         4 . The polymer blend of  claim 2 , wherein 
 the styrenic co-monomer is selected from the group consisting of styrene, 2-methylstyrene 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, α-methylstyrene, and mixtures thereof; and    the unsaturated oxygen or nitrogen containing co-monomer is selected from the group consisting of methyl acrylate, ethyl methacrylate, methyl acrylate, ethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, acrylonitrile, and mixtures thereof.    
     
     
         5 . The polymer blend of  claim 2  comprising 60 wt % or more of the coupled conjugated diene/monovinylarene block copolymer.  
     
     
         6 . The polymer blend of  claim 3  comprising 60 wt % or more of the coupled conjugated diene/monovinylarene block copolymer.  
     
     
         7 . The polymer blend of  claim 4  comprising 60 wt % or more of the coupled conjugated diene/monovinylarene block copolymer.  
     
     
         8 . The polymer blend of  claim 7 , wherein 
 the monovinylarene monomer is selected from the group consisting of styrene, 2-methylstyrene 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, α-methylstyrene, and mixtures thereof; and    the conjugated diene monomer is selected from butadiene, isoprene, 2,3-dimethylbutadiene and mixtures thereof.    
     
     
         9 . A polymer comprising at least one coupled conjugated diene/monovinylarene block copolymer and at least one styrenic polymer, wherein 
 the coupled conjugated diene/monovinylarene block copolymer is produced by a process comprising sequentially contacting under polymerization conditions at least one monovinylarene monomer, an organoalkali metal initiator, at least one conjugated diene monomer, and thereafter coupling with a polyfunctional coupling agent to form the block copolymer;    at least three consecutive monomer mixture charges containing monovinylarene monomer and conjugated diene monomer are provided to produce at least three consecutive conjugated diene/monovinylarene tapered blocks in the block copolymer;    all the monovinylarene monomer and conjugated diene monomer contained in each charge are added at the beginning of the charge allowing excess of monomer to be present in the reactor;    the at least one monovinylarene monomer contains from 8 to 18 carbon atoms, and the at least one conjugated diene monomer contains from 4 to 12 carbon atoms;    the styrenic polymer is selected from the group consisting of at least one copolymer produced by copolymerizing at least one styrenic co-monomer and at least one unsaturated oxygen or nitrogen containing co-monomer; wherein    the monovinylarene monomer is selected from the group consisting of styrene, 220 methylstyrene 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, α-methylstyrene, and mixtures thereof;    the conjugated diene monomer is selected from butadiene, isoprene, 2,3-dimethylbutadiene and mixtures thereof;    the styrenic co-monomer is selected from the group consisting of styrene, 225 methylstyrene 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, α-methylstyrene, and mixtures thereof; and    the unsaturated oxygen or nitrogen containing co-monomer is selected from the group consisting of methyl acrylate, ethyl methacrylate, methyl acrylate, ethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, acrylonitrile, and mixtures thereof.    
     
     
         10 . The polymer blend of  claim 9  comprising 60 wt % or more of the coupled conjugated diene/monovinylarene block copolymer.  
     
     
         11 . A polymer comprising at least one coupled conjugated diene/monovinylarene block copolymer and at least one styrenic polymer, wherein 
 the coupled conjugated diene/monovinylarene block copolymer is produced by a process comprising sequentially contacting under polymerization conditions at least one monovinylarene monomer, an organoalkali metal initiator, at least one conjugated diene monomer, and thereafter coupling with a polyfunctional coupling agent to form the block copolymer;    at least three consecutive monomer mixture charges containing monovinylarene monomer and conjugated diene monomer are provided to produce at least three consecutive conjugated diene/monovinylarene tapered blocks in the block copolymer;    all the monovinylarene monomer and conjugated diene monomer contained in each charge are added at the beginning of the charge allowing excess of monomer to be present in the reactor;    the at least one monovinylarene monomer contains from 8 to 18 carbon atoms, and the at least one conjugated diene monomer contains from 4 to 12 carbon atoms;    the styrenic polymer is selected from the group consisting of at least one copolymer produced by copolymerizing at least one styrenic co-monomer and at least one unsaturated oxygen or nitrogen containing co-monomer; wherein    the polymer blend comprises 60 wt % or more of the coupled conjugated diene/monovinylarene block copolymer;    the monovinylarene monomer is selected from the group consisting of styrene, 2-methylstyrene 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, and mixtures thereof;    the conjugated diene monomer is selected from butadiene, isoprene, and mixtures thereof;    the styrenic co-monomer is selected from the group consisting of styrene, 2-methylstyrene 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 4-t-butylstyrene, and mixtures thereof; and    the unsaturated oxygen or nitrogen containing co-monomer is selected from the group consisting of methyl acrylate, ethyl methacrylate, methyl acrylate, ethyl methacrylate, and mixtures thereof.