Ethylene polymer blend and polymerization process for preparation thereof

Claim 2

A NORMALLY SOLID, HOMOGENEOUS, HIGH IMPACT, HIGH DENSITY ETHYLENE POLYMER BLEND COMPRISING A MAJOR AMOUNT OF INTERMEDIATE MOLECULAR WEIGHT HIGH DENSITY ETHYLENE POLYMER CONSISTING ESSENTIALLY OF ETHYLENE AND OPTIONALLY OTHER A-OLEFIN COMONOMER UNITS AND A MONOR AMOUNT OF AT LEAST ABOUT 3 WEIGHT PERCENT BASED ON THE BLEND OF HIGH MOLECULAR WEIGHT, NON-ELASTOMERIC ETHYLENE/A-OLEFIN COPLYMER HAVING A CRYSTALLINITY OF AT LEAST 5 PERCENT AND AN A-OLEFIN COMONOMER CONTENT FROM ABOUT 12 TO ABOUT 40 WEIGHT PERCENT BASED ON THE COPOLYMER, SAID HIGH MOLECULAR WEIGHT COPOLYMER HAVING (1) MELT FLOW VISCOSITY VALUE NOT GREATER THAN ABOUT ONE-FIFTH THE MELT FLOW VISCOSITY VAUE OF SAID INTERMEDIATE MOLECULAR WEIGHT POLYMER AND (2) AN A-OLEFIN COMONMOMER CONTENT AT LEAST ABOUT 3 TIMES ON A WEIGHT BASIS OF ANY A-OLEFIN COMONOMER CONTENT OF SAID INTERMEDIATE MOLECULAR WEIGHT POLYMER, BOTH OF SAID ETHYLENE POLYMERS HAVING BEEN PREPARED UNDER SOLUTION POLYMERIZATION CONDITIONS AND BLENDED IN THE LIQUID STATE.

Claim 3

The blend according to claim 1 comprising (A) at least about 60 weight percent of intermediate molecular weight ethylene polymer containing from about 0 to about 6 weight percent based on the polymer of polymerized aliphatic Alpha -monoolefin with from 3 to 12 carbon atoms and having density of from about 0.945 to about 0.970 gm/cc and melt flow viscosity of from about 0.5 to about 500 decigrams per minute and (b) from about 5 to about 40 weight percent of a high molecular weight, non-elastomeric ethylene/ Alpha -olefin copolymer having a crystallinity of at least about 10 percent and containing from about 16 to about 40 weight percent based on the copolymer of polymerized aliphatic Alpha -monoolefin with from 3 to 12 carbon atoms and having density of from about 0.870 to about 0.955 gm/cc and melt flow viscosity of from about 0.0001 to about 6 decigrams/minute, said high molecular weight copolymer having (1) a melt flow viscosity value not greater than about one-tenth the melt flow viscosity value of said intermediate molecular weight polymer and (2) an Alpha -olefin comonomer content at least about 10 times on a weight basis the Alpha -olefin comonomer content of said intermediate molecular weight polymer, said blend having an Alpha -olefin comonomer content of from about 1 to about 15 weight percent based on the blend, a melt flow viscosity of from about 0.2 to about 20 decigrams/minute and density of from about 0.940 to about 0.967 gm/cc.

Claim 4

The blend according to claim 2 wherein the intermediate molecular weight ethylene polymer is polyethylene.

Claim 5

The blend according to claim 3 wherein the high molecular weight ethylene/ Alpha -olefin copolymer is an ethylene/propylene copolymer containing from about 16 to about 25 weight percent based on the copolymer of polymerized propylene.

Claim 6

The blend according to claim 4 wherein the blend has an Izod impact strength of from about 1.0 to about 10.0 foot-pounds/inch of notch, a density of from about 0.946 to about 0.964 gm/cc, and a melt flow viscosity in the range of from about 1.0 to about 10.0 decigrams/minute.

Claim 7

The blend of claim 1 wherein the copolymer contains 16 weight percent of polymerized propylene.

Claim 8

The blend of claim 2 wherein the copolymer contains 24.9 weight percent of polymerized propylene.

Claim 9

A process for the preparation of a normally solid, homogeneous, high impact, high density ethylene polymer blend which process comprises the steps of (1) polymerizing ethylene in a solvent in a primary polymerization zone in the presence of a Ziegler catalyst at solution polymerization temperature under pressure sufficient to insure that substantially no vapor phase is formed; (2) copolymerizing ethylene and an Alpha -olefin in a solvent in an auxiliary polymerization zone in the presence of a Ziegler catalyst at solution polymerization temperature under pressure sufficient to substantially insure that no vapor phase is formed, said polymerization of steps (1) and (2) being carried out in cooperation such that (A) the resultant polymer product of said auxiliary zone has a melt flow viscosity value not greater than one-fifth the melt flow viscosity value of the resultant polymer product of said primary polymerization zone and (B) said product of said auxiliary zone having an Alpha -olefin comonomer content of at least 3 times on a weight basis the Alpha -olefin comonomer content of said product of said primary polymerization zone; and (3) combining the resultant polymerization products of said pOlymerization zones in liquid state in proportion such that the polymer product of said primary zone constitutes a major amount of the resultant blend.

Claim 10

A process for the preparation of a normally solid, homogeneous, high impact, high density ethylene polymer blend which process comprises the steps of (1) polymerizing ethylene in a solvent in a primary polymerization zone in the presence of a Ziegler catalyst at solution polymerization temperature under pressure sufficient to insure that substantially no vapor phase is formed; (2) copolymerizing ethylene and an Alpha -olefin in a solvent in an auxiliary polymerization zone in the presence of a Ziegler catalyst at solution polymerization temperature under pressure sufficient to substantially insure that no vapor phase is formed, said polymerization of steps (1) and (2) being carried out in cooperation such that (A) the resultant polymer product of said auxiliary zone has a melt flow viscosity value not greater than one-fifth the melt flow viscosity value of the resultant polymer product of said primary polymerization zone and (B) said product of said auxiliary zone having an Alpha -olefin comonomer content of at least 3 times on a weight basis the Alpha -olefin comonomer content of said product of said primary polymerization zone; and (3) combining the resultant polymerization products of said pOlymerization zones in liquid state in proportion such that the polymer product of said primary zone constitutes a major amount of the resultant blend.