Rubber modified styrenic copolymers and their use in forming oriented articles

Abstract

An oriented, i.e. uniaxial or biaxial, thermoplastic article, e.g. extruded sheet, blown film, and cast film, comprising a first component comprising a continuous phase and a dispersed phase, where A) the continuous phase contains a polymer composition resulting from the polymerization of a monomer mixture containing a styrenic monomer and an alkyl (meth)acrylate monomer in the presence of the dispersed phase; and B) the dispersed phase contains one or more block copolymer selected from diblock and triblock copolymers of styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, styrene-isoprene-styrene, partially hydrogenated styrene-isoprene-styrene, wherein the oriented thermoplastic article has a thickness ranging from 0.02 mm to 0.50 mm, a tensile strength ranging from 15 Mpa to 70 Mpa as measured by ASTM D 882, an impact value ranging between 0.05 ft. lb/mil to 1.0 ft. lb/mil as measured by ASTM D 3763, and a Haze value less than 10% as measured by ASTM D 1003.

1 . An oriented thermoplastic article, comprising a first component comprising a continuous phase and a dispersed phase, wherein: 
 A) the continuous phase comprises a polymer composition resulting from the polymerization of a monomer mixture comprising (i) from about 25 parts by weight to 75 parts by weight of a styrenic monomer and (ii) from about 25 parts by weight to 75 parts by weight of an alkyl (meth)acrylate monomer, wherein the alkyl group is a C 1  to C 12  linear, branched or cyclic alkyl group, in the presence of the dispersed phase; and    B) the dispersed phase comprises from about 2 parts by weight to about 50 parts by weight of one or more block copolymers selected from the group consisting of diblock and triblock copolymers of styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, styrene-isoprene-styrene, partially hydrogenated styrene-isoprene-styrene, for a total of 100 parts by weight of the combination of A) and B), and    wherein said oriented thermoplastic article has a thickness ranging from about 0.02 mm to about 0.50 mm, a tensile strength ranging from about 15 Mpa to about 70 Mpa as measured by ASTM D 882, an impact value ranging from about 0.05 ft. lb/mil to about 1.0 ft. lb/mil as measured by ASTM D 3763, and a Haze value less than 10% as measured by ASTM D 1003.    
   
   
       2 . The oriented thermoplastic article of  claim 1  wherein said oriented thermoplastic article is an uniaxially oriented thermoplastic article.  
   
   
       3 . The oriented thermoplastic article of  claim 2  wherein said uniaxially oriented thermoplastic article is selected from the group consisting of extruded sheet, blown film, and cast film.  
   
   
       4 . The oriented thermoplastic article of  claim 1  wherein said oriented thermoplastic article is a biaxially oriented thermoplastic article.  
   
   
       5 . The oriented thermoplastic article of  claim 4  wherein said biaxially oriented thermoplastic article is selected from the group consisting of extruded sheet, blown film, and cast film.  
   
   
       6 . The oriented thermoplastic article of  claim 1  wherein the dispersed phase B) is present as discrete particles dispersed within the continuous phase A).  
   
   
       7 . The oriented thermoplastic article of  claim 1  wherein the volume average particle size of the dispersed phase B) is from about 0.1 μm to about 2 μm.  
   
   
       8 . The oriented thermoplastic article of  claim 1  wherein the difference between the refractive index of the continuous phase A) and the dispersed phase B) is not more than 0.01.  
   
   
       9 . The oriented thermoplastic article of  claim 1  wherein the styrenic monomer is selected from the group consisting of styrene, p-methyl styrene, tertiary butyl styrene, dimethyl styrene, nuclear brominated or chlorinated derivatives thereof and combinations thereof.  
   
   
       10 . The oriented thermoplastic article of  claim 1  wherein the alkyl (meth)acrylate monomer comprises methylmethacrylate and optionally butyl acrylate.  
   
   
       11 . The oriented thermoplastic article of  claim 1  wherein the block copolymer has a weight average molecular weight of not less than about 75,000.  
   
   
       12 . The oriented thermoplastic article of  claim 1  wherein the block copolymer is a linear or radial block copolymer.  
   
   
       13 . The oriented thermoplastic article of  claim 1  wherein the block copolymer is a triblock styrene-butadiene-styrene or styrene-isoprene-styrene copolymer having a weight average molecular weight of from about 175,000 to about 275,000.  
   
   
       14 . The oriented thermoplastic article of  claim 1  wherein at least some of the polymers in A) are grafted onto the block copolymer in B).  
   
   
       15 . The oriented thermoplastic article of  claim 1  further comprising a printed layer over at least a portion of a surface of the thermoplastic sheet.  
   
   
       16 . The oriented thermoplastic article of  claim 1  wherein the monomer mixture further comprises a chain transfer agent.  
   
   
       17 . A multi-layer structure comprising at least two layers and wherein at least one layer of said multi-layer structure is comprised of the oriented thermoplastic article of  claim 1 .  
   
   
       18 . A multi-layer structure of  claim 17  wherein at least the other layer of said multi-layer structure is comprised of a rubber modified polystyrene composition.  
   
   
       19 . A multi-layer structure of  claim 17  wherein at least the other layer of said multi-layer structure is comprised of a polyethylene composition.  
   
   
       20 . A multi-layer structure of  claim 17  wherein at least the other layer of said multi-layer structure is comprised of an ethylvinyl acetate composition.  
   
   
       21 . A process for preparing an oriented thermoplastic article, comprising: 
 forming a thermoplastic composition comprising a continuous phase and a dispersed phase, wherein    A) the continuous phase comprises a polymer composition resulting from the polymerization of a monomer mixture comprising (i) from about 25 to 75 parts by weight of a styrenic monomer and (ii) from about 25 to 75 parts by weight of an alkyl (meth)acrylate monomer, wherein the alkyl group is a C 1  to C 12  linear, branched or cyclic alkyl group, in the presence of the dispersed phase; and    B) the dispersed phase comprises from about 2 to about 50 parts by weight of one or more block copolymers selected from the group consisting of diblock and triblock copolymers of styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, styrene-isoprene-styrene, partially hydrogenated styrene-isoprene-styrene, for a total of 100 parts by weight of the combination of A) and B);    maintaining said thermoplastic composition in a molten state while mixing said composition; and    forming said oriented thermoplastic article; and    wherein said oriented thermoplastic article has a thickness ranging from about 0.02 mm to about 0.50 mm, a tensile strength ranging from about 15 Mpa to about 70 Mpa as measured by ASTM D 882, an impact value ranging from about 0.05 ft. lb/mil to about 1.0 ft. lb/mil as measured by ASTM D 3763, and a Haze value less than 10% as measured by ASTM D 1003.    
   
   
       22 . The process of  claim 21  wherein said oriented thermoplastic article is an uniaxially oriented thermoplastic article.  
   
   
       23 . The process of  claim 22  wherein said uniaxially oriented thermoplastic article is selected from the group consisting of extruded sheet, blown film, and cast film.  
   
   
       24 . The process of  claim 21  wherein said oriented thermoplastic article is an biaxially oriented thermoplastic article.  
   
   
       25 . The process of  claim 24  wherein said biaxially oriented thermoplastic article is selected from the group consisting of extruded sheet, blown film, and cast film.  
   
   
       26 . The process of  claim 21  wherein the dispersed phase B) is present as discrete particles dispersed within the continuous phase A).  
   
   
       27 . The process of  claim 21  wherein the volume average particle size of the dispersed phase B) is from about 0.1 μm to about 2 μm.  
   
   
       28 . The process of  claim 21  wherein the difference between the refractive index of the continuous phase A) and the dispersed phase B) is not more than 0.01.  
   
   
       29 . The process of  claim 21  wherein the styrenic monomer is selected from the group consisting of styrene, p-methyl styrene, tertiary butyl styrene, dimethyl styrene, nuclear brominated or chlorinated derivatives thereof and combinations thereof.  
   
   
       30 . The process of  claim 21  wherein the alkyl (meth)acrylate monomer comprises methylmethacrylate and optionally butyl acrylate.  
   
   
       31 . The process of  claim 21  wherein the block copolymer has a weight average molecular weight of not less than about 75,000.  
   
   
       32 . The process of  claim 21  wherein the block copolymer is a linear or radial block copolymer.  
   
   
       33 . The process of  claim 21  wherein the block copolymer is a triblock styrene-butadiene-styrene or styrene-isoprene-styrene copolymer having a weight average molecular weight of from about 175,000 to about 275,000.  
   
   
       34 . The process of  claim 21  wherein at least some of the polymers in A) are grafted onto the block copolymer in B).  
   
   
       35 . The process of  claim 21  wherein the monomer mixture further comprises a chain transfer agent.  
   
   
       36 . A thermoplastic composition for an oriented thermoplastic article comprising a first component comprising a continuous phase and a dispersed phase, where: 
 A) the continuous phase comprises a polymer composition resulting from the polymerization of a monomer mixture comprising (i) from about 25 parts by weight to 75 parts by weight of a styrenic monomer and (ii) from about 25 parts by weight to 75 parts by weight of an alkyl (meth)acrylate monomer, wherein the alkyl group is a C 1  to C 12  linear, branched or cyclic alkyl group, in the presence of the dispersed phase; and    B) the dispersed phase comprises from about 2 parts by weight to about 50 parts by weight of one or more block copolymers selected from the group consisting of diblock and triblock copolymers of styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, styrene-isoprene-styrene, partially hydrogenated styrene-isoprene-styrene, for a total of 100 parts by weight of the combination of A) and B), and    wherein said first component ranges in an amount of about 0.1 to about 100% by weight, based on the weight of the thermoplastic composition.    
   
   
       37 . A thermoplastic composition of  claim 36 , wherein said composition further comprises about 70% by weight of said first component, and about 30% by weight of a rubber modified polystyrene.  
   
   
       38 . A thermoplastic composition of  claim 36 , wherein said composition further comprises about 70% by weight of said first component, about 15% by weight of a rubber modified polystyrene, and about 15% by weight of a tie component.  
   
   
       39 . A thermoplastic composition of  claim 36 , wherein said composition further comprises about 40% by weight of said first component, about 40% by weight of a rubber modified polystyrene, and about 20% by weight of a tie component.  
   
   
       40 . A thermoplastic composition of  claim 36 , wherein said composition further comprises about 70% by weight of said first component, and about 30% by weight a tie component.  
   
   
       41 . A thermoplastic composition of  claim 36  wherein said thermoplastic article is an uniaxially oriented thermoplastic article.  
   
   
       42 . A thermoplastic composition of  claim 41  wherein said uniaxially oriented thermoplastic article is selected from the group consisting of extruded sheet, blown film, and cast film.  
   
   
       43 . A thermoplastic composition of  claim 41  wherein said thermoplastic article is a biaxially oriented thermoplastic article.  
   
   
       44 . A thermoplastic composition of  claim 43  wherein said biaxially oriented thermoplastic article is selected from the group consisting of extruded sheet, blown film, and cast film.