High melt strength, propylene polymer, process for making it, and use thereof

An extrusion coating composition comprising an irradiated normally solid, high molecular weight, non-linear, substantially gel-free, propylene polymer material, having strain hardening elongational viscosity and enhanced melt strength as indicated by a melt tension of greater than or equal to 7.1 selected from the group consisting essentially of:

• (1) a propylene polymer composition consisting essentially of:
• (a) from 10 to 50% of a propylene homopolymer having an isotactic index of from 80 to 99%, or a copolymer selected from the group consisting of (i) propylene and ethylene, (ii) propylene, ethylene and a CH.sub.2 .dbd.CHR alpha-olefin, where R is a C.sub.2-8 straight or branched alkyl, and (iii) propylene and an alpha-olefin, as defined above in (a)(ii), wherein said copolymer contains from 85 to 99% propylene and having an isotactic index greater than 80 to 99%,
• (b) from 5 to 20% of a semi-crystalline, essentially linear copolymer fraction having a crystallinity of about 20 to 60%, by differential scanning calorimetry (DSC), wherein the copolymer is selected from the group consisting of (i) ethylene and propylene containing over 55% ethylene;
• (ii) ethylene, propylene, and an alpha-olefin, as defined above in (a)(ii), containing from 1 to 10% of the alpha-olefin and over 55% up to 98% of both ethylene and alpha-olefin;
• and (iii) ethylene and an alpha-olefin, as defined in (a)(ii), containing over 55% up to 98% of said alpha-olefin, which copolymer is insoluble in xylene at room or ambient temperature, and
• (c) from 40 to 80% of a copolymer fraction selected from the group consisting of a copolymer of (i) ethylene and propylene wherein the copolymer contains from 20% to less than 40% ethylene;
• (ii) ethylene, propylene, and an alpha-olefin, as defined in (a)(ii), wherein the alpha-olefin is present in an amount of from 1 to 10% and the amount of ethylene and alpha-olefin present is from 20% to less than 40%;
• and (iii) ethylene and an alpha-olefin, as defined in (a)(ii), containing from 20 to less than 40% of the alpha-olefin, and optionally containing 0.5 to 10% of a diene, said copolymer fraction being soluble in xylene at ambient temperature, and having an intrinsic viscosity of from 1.7 to 3.0 dl/g, wherein the total amount of ethylene units or said alpha-olefin units or of ethylene and said alpha-olefin units when both are present in the composition is from 15 to 35%, the total amount of (b) and (c) fractions, based on the total olefin polymer composition is from about 65% to 80%, the weight ratio of (b)/(c) is from 0.1 to about 0.3 and the total content of ethylene or C.sub.4-8 alpha-olefin or combination thereof in (b+c) is less than 50%;
• and
• (2) a propylene polymer composition consist essentially of:
• (a) 10-60 parts by weight of homopolymer polypropylene with isotactic index greater than 90to 99, or of crystalline propylene copolymer with ethylene, with a CH.sub.2 .dbd.CHR olefin where R is a 2-6 carbon alkyl radical, or combinations thereof, containing over 85% by weight of propylene and having an isotactic index greater than 85 to 94%;
• (b) 8-40 parts by weight of a semi-crystalline, polymer fraction containing ethylene and propylene, having an ethylene content greater than 50% and insoluble in xylene at room temperature;
• (c) 30-60 parts by weight of an amorphous ethylene-propylene copolymer fraction containing optionally small proportions of a diene, soluble in xylene at room temperature and containing 40 to 70% by weight ethylene.

A film forming composition comprising an irradiated normally solid, high molecular weight, non-linear, substantially gel-free, propylene polymer material having strain hardening elongational viscosity and enhanced melt strength as indicated by a melt tension of greater or equal to 7.1 selected from the group consisting essentially of:

• (1) a propylene polymer composition consisting essentially of:
• (a) from 10 to 50% of a propylene homopolymer having an isotactic index of from 80 to 99%, or a copolymer selected from the group consisting of (i) propylene and ethylene, (ii) propylene, ethylene and a CH.sub.2 .dbd.CHR alpha-olefin, where R is a C.sub.2-8 straight or branched alkyl, and (iii) propylene and an alpha-olefin, as defined above in (a)(ii), wherein said copolymer contains from 85 to 99% propylene and having an isotactic index greater than 80 to 99%,
• (b) from 5 to 20% of a semi-crystalline, essentially linear copolymer fraction having a crystallinity of about 20 to 60%, by differential scanning calorimetry (DSC), wherein the copolymer is selected from the group consisting of (i) ethylene and propylene containing over 55% ethylene;
• (ii) ethylene, propylene, and an alpha-olefin, as defined above in (a)(ii), containing from 1to 10% of the alpha-olefin and over 55% up to 98% of both ethylene and alpha-olefin;
• and (iii) ethylene and an alpha-olefin, as defined in (a)(ii), containing over 55% up to 98% of said alpha-olefin, which copolymer is insoluble in xylene at room or ambient temperature, and
• (c) from 40 to 80% of a copolymer fraction selected from the group consisting of a copolymer of (i) ethylene and propylene wherein the copolymer contains from 20% to less than 40% ethylene;
• (ii) ethylene, propylene, and an alpha-olefin, as defined in (a)(ii), wherein the alpha-olefin is present in an amount of from 1 to 10% and the amount of ethylene and alpha-olefin present is from 20% to less than 40%;
• and (iii) ethylene and an alpha-olefin, as defined in (a)(ii), containing from 20 to less than 40% of the alpha-olefin, and optionally containing 0.5 to 10% of a diene, said copolymer fraction being soluble in xylene at ambient temperature, and having an intrinsic viscosity of from 1.7 to 3.0 dl/g, wherein the total amount of ethylene units or said alpha-olefin units or of ethylene and said alpha-olefin units when both are present in the composition is from 15 to 35%, the total amount of (b) and (c) fractions, based on the total olefin polymer composition is from about 65% to 80%, the weight ratio of (b)/(c) is from 0.1 to about 0.3 and the total content of ethylene or C.sub.4-8 alpha-olefin or combination thereof in (b+c) is less than 50%;
• and
• (2) a propylene polymer composition consist essentially of:
• (a) 10-60 parts by weight of homopolymer polypropylene with isotactic index greater than 90to 99, or of crystalline propylene copolymer with ethylene, with a CH.sub.2 .dbd.CHR olefin where R is a 2-6 carbon alkyl radical, or combinations thereof, containing over 85% by weight of propylene and having an isotactic index greater than 85 to 94%;
• (b) 8-40 parts by weight of a semi-crystalline, polymer fraction containing ethylene and propylene, having an ethylene content greater than 50% and insoluble in xylene at room temperature;
• (c) 30-60 parts by weight of an amorphous ethylene-propylene copolymer fraction containing optionally small proportions of a diene, soluble in xylene at room temperature and containing 40 to 70% by weight ethylene.

Film comprising an irradiated normally solid, high molecular weight, non-linear, substantially gel-free, propylene polymer material having strain hardening elongational viscosity and enhanced melt strength as indicated by a melt tension of greater or equal to 7.1 selected from the group consisting essentially of:

• (1) a propylene polymer composition consisting essentially of:
• (a) from 10 to 50% of a propylene homopolymer having an isotactic index of from 80 to 99%, or a copolymer selected from the group consisting of (i) propylene and ethylene, (ii) propylene, ethylene and a CH.sub.2 .dbd.CHR alpha-olefin, where R is a C.sub.2-8 straight or branched alkyl, and (iii) propylene and an alpha-olefin, as defined above in (a)(ii), wherein said copolymer contains from 85 to 99% propylene and having an isotactic index greater than 80 to 99%,
• (b) from 5 to 20% of a semi-crystalline, essentially linear copolymer fraction having a crystallinity of about 20 to 60%, by differential scanning calorimetry (DSC), wherein the copolymer is selected from the group consisting of (i) ethylene and propylene containing over 55% ethylene;
• (ii) ethylene, propylene, and an alpha-olefin, as defined above in (a)(ii), containing from 1 to 10% of the alpha-olefin and over 55% up to 98% of both ethylene and alpha-olefin;
• and (iii) ethylene and an alpha-olefin, as defined in (a)(ii), containing over 55% up to 98% of said alpha-olefin, which copolymer is insoluble in xylene at room or ambient temperature, and
• (c) from 40 to 80% of a copolymer fraction selected from the group consisting of a copolymer of (i) ethylene and propylene wherein the copolymer contains from 20% to less than 40% ethylene;
• (ii) ethylene, propylene, and an alpha-olefin, as defined in (a)(ii), wherein the alpha-olefin is present in an amount of from 1 to 10% and the amount of ethylene and alpha-olefin present is from 20% to less than 40%;
• and (iii) ethylene and an alpha-olefin, as defined in (a)(ii), containing from 20 to less than 40% of the alpha-olefin, and optionally containing 0.5 to 10% of a diene, said copolymer fraction being soluble in xylene at ambient temperature, and having an intrinsic viscosity of from 1.7 to 3.0 dl/g, wherein the total amount of ethylene units or said alpha-olefin units or of ethylene and said alpha-olefin units when both are present in the composition is from 15 to 35%, the total amount of (b) and (c) fractions, based on the total olefin polymer composition is from about 65% to 80%, the weight ratio of (b)/(c) is from 0.1 to about 0.3 and the total content of ethylene or C.sub.4-8 alpha-olefin or combination thereof in (b+c) is less than 50%;
• and
• (2) a propylene polymer composition consist essentially of:
• (a) 10-60 parts by weight of homopolymer polypropylene with isotactic index greater than 90to 99, or of crystalline propylene copolymer with ethylene, with a CH.sub.2 .dbd.CHR olefin where R is a 2-6 carbon alkyl radical, or combinations thereof, containing over 85% by weight of propylene and having an isotactic index greater than 85 to 94%;
• (b) 8-40 parts by weight of a semi-crystalline, polymer fraction containing ethylene and propylene, having an ethylene content greater than 50% and insoluble in xylene at room temperature;
• (c) 30-60 parts by weight of an amorphous ethylene-propylene copolymer fraction containing optionally small proportions of a diene, soluble in xylene at room temperature and containing 40 to 70% by weight ethylene.