Patent ID: 6306518
Filing Date: 2001-10-23
Classification: B32B,C08K,C08L,Y10T

Abstract:
A co-extruded sheet comprising:(1) at least one outer layer comprising(a) a propylene polymer material selected from the group consisting of(i) a propylene homopolymer or a copolymer of propylene and ethylene or a C.sub.4 -C.sub.8 .alpha.-olefin, both having a melt flow rate of 0.5 to 15 dg/min, wherein the polymerized ethylene or polymerized .alpha.-olefin content of the copolymer is not greater than 20%, and(ii) a graft copolymer comprising a backbone of a propylene polymer material, having graft polymerized thereto polymerized monomers selected from the group consisting of(I) at least one acrylic monomer,(II) at least one styrenic monomer, and(III) mixtures of (I) and (II), and(b) about 0.15% to about 0.70% of a nucleating agent having a melting point greater than 265.degree. C. when the propylene polymer material is (i) or about 0.5% to about 1.5% of a nucleating agent having a melting point greater than 265.degree. C. when the propylene polymer material is (ii), and(2) another layer comprising:(a) about 5% to about 50% of a propylene polymer having strain hardening elongational viscosity selected from the group consisting of (i) a propylene homopolymer, and (ii) a copolymer of propylene and ethylene or a C.sub.4 -C.sub.10 .alpha.-olefin, provided that when the olefin is ethylene, the maximum polymerized ethylene content is about 5%, and when the olefin is a C.sub.4 -C.sub.10 .alpha.-olefin, the maximum polymerized content thereof is 20%,(b) optionally about 5% to about 40% of an inorganic filler,(c) about 2% to about 50% of an olefin polymer composition comprising:(i) about 10 parts to about 60 parts by weight of a crystalline propylene homopolymer having an isotactic index greater than 80, or a crystalline copolymer from monomers selected from the group consisting of (1) propylene and ethylene, (2) propylene, ethylene and a C.sub.4 -C.sub.8 .alpha.-olefin, and (3) propylene and a C.sub.4 -C.sub.8 .alpha.-olefin, the copolymer having a polymerized propylene content of more than 85% by weight and an isotactic index greater than 85;(ii) about 5 parts to about 25 parts by weight of a copolymer of ethylene and propylene or a C.sub.4 -C.sub.8 .alpha.-olefin that is insoluble in xylene at ambient temperature; and(iii) about 30 parts to about 70 parts by weight of an elastomeric copolymer from monomers selected from the group consisting of (1) ethylene and propylene, (2) ethylene, propylene, and a C.sub.4 -C.sub.8 .alpha.-olefin, and (3) ethylene and a C.sub.4 -C.sub.8 .alpha.-olefin, the copolymer optionally containing about 0.5% to about 10% by weight of a polymerized diene, and containing less than 70% by weight of polymerized ethylene and being soluble in xylene at ambient temperature and having an intrinsic viscosity measured in decahydronaphthalene at 135.degree. C. of about 1.5 to about 4.0 dl/g;the total of (ii) and (iii), based on the total olefin polymer composition being from about 50% to about 90%, and the weight ratio of (ii)/(iii) being less than 0.4, wherein the composition is prepared by polymerization in at least two stages and has a flexural modulus of less than 150 MPa; and(d) optionally about 5% to about 70% of at least one propylene polymer material selected from the group consisting of:(i) a crystalline homopolymer of propylene having an isotactic index greater than 80;(ii) a crystalline copolymer of propylene and an olefin selected from the group consisting of ethylene and C.sub.4 -C.sub.10 .alpha.-olefins, provided that when the olefin is ethylene, the maximum polymerized ethylene content is 10% by weight, and when the olefin is a C.sub.4 -C.sub.10 .alpha.-olefin, the maximum polymerized content thereof is 20% by weight, the copolymer having an isotactic index greater than 85;(iii) a crystalline terpolymer of propylene and two olefins selected from the group consisting of ethylene and C.sub.4 -C.sub.8 .alpha.-olefins, provided that the maximum polymerized C.sub.4 -C.sub.8 .alpha.-olefin content is 20% by weight, and, when ethylene is one of the olefins, the maximum polymerized ethylene content is 5% by weight, the terpolymer having an isotactic index greater than 85;(iv) a thermoplastic olefin comprising:(1) about 10% to about 60% of a propylene homopolymer having an isotactic index greater than 80, or a crystalline copolymer from monomers selected from the group consisting of (a) ethylene and propylene, (b) ethylene, propylene, and a C.sub.4 -C.sub.8 .alpha.-olefin, and (c) ethylene and a C.sub.4 -C.sub.8 .alpha.-olefin, the copolymer having a polymerized propylene content greater than 85% and an isotactic index of greater than 85%;(2) about 20% to about 60% of an amorphous copolymer from monomers selected from the group consisting of (a) ethylene and propylene, (b) ethylene, propylene and a C.sub.4 -C.sub.8 .alpha.-olefin, and (c) ethylene and a C.sub.4 -C.sub.8 .alpha.-olefin, the copolymer optionally containing about 0.5% to about 10% of a polymerized diene, and containing less than 70% polymerized ethylene and being soluble in xylene at ambient temperature; and(3) about 3% to about 40% of a copolymer of ethylene and propylene or a C.sub.4 -C.sub.8 .alpha.-olefin that is insoluble in xylene at ambient temperature,wherein the composition has a flexural modulus of greater than 150 but less than 1200 MPa; and(v) a heterophasic polyolefin composition comprising:(1) about 30% to about 98% of a polymeric material selected from the group consisting of a propylene homopolymer having an isotactic index greater than 90, and a crystalline copolymer having an isotactic index greater than 85 of propylene and at least one .alpha.-olefin of the formula CH.sub.2.dbd.CHR, where R is H or a C.sub.2 -C.sub.6 alkyl group, the polymerized .alpha.-olefin being less than 10% of the copolymer when R is H and being less than 20% when R is a C.sub.2 -C.sub.6 alkyl group or a combination thereof with R.dbd.H, and(2) about 2% to about 70% of an elastomeric copolymer of propylene and an .alpha.-olefin of the formula CH.sub.2.dbd.CHR, where R is H or a C.sub.2 -C.sub.8 alkyl group, the polymerized .alpha.-olefin being about 45% to about 75% of the elastomeric copolymer, and about 10% to about 40% of the elastomeric copolymer being insoluble in xylene at ambient temperature, or an elastomeric copolymer of ethylene and a C.sub.4 -C.sub.8 .alpha.-olefin, having a polymerized .alpha.-olefin content of about 15% to about 60%,wherein (a)+(c), (a)+(b)+(c), or (a)+(b)+(c)+(d)=100% and layer (1) comprises about 5% to about 60% of the total thickness of the sheet.