High toughness propylene polymer compositions

Claim 2

A composition having a melt flow between about 5 and about 50 dg/min (ASTM D1238--Condition L), and a high notched impact value, said composition being obtained by first peroxide-contacting an impact-improved propylene-ethylene copolymer and then melt mixing the resulting visbroken propylene polymer with a linear low density ethylene copolymer and a high density ethylene homopolymer, wherein (a) said impact-improved propylene-ethylene polymer has a melt flow (ASTM D1238-Condition L) of about 0.5-15 dg/min and an elastomeric propylene-ethylene copolymer content of 5-50% by weight, the copolymer fraction having an ethylene content of 30-95% by weight, which propylene-ethylene polymer is the product of sequential polymerization of propylene and a propylene-ethylene mixture over a titanium halide-containing coordination catalyst; (b) said high density ethylene homopolymer has a density in the range from 0.941 to 0.965 grams per cubic centimeter and a melt index (ASTM D1238-Condition E) in the range from 0 to 20 dg/min; (c) said linear low density ethylene copolymer is the product of random polymerization of ethylene with up to 15 mole percent of at least one C 3 -C 8 alpha olefin monomer over a transition metal-based coordination catalyst and which has a density below 0.935 and a melt index (ASTM D1238-Condition E) not exceeding 16; and (d) said composition comprises 50-90% by weight of said impact-modified propylene polymer, 3-45% by weight of said high density ethylene homopolymer, 3-45% by weight of said linear low density ethylene copolymer, wherein the weight ratio of said high density ethylene homopolymer to said linear low density ethylene copolymer is between 80:20 and 20:80.

Claim 3

The composition according to claim 1 wherein said linear low density ethylene copolymer is an ethylene-1-butene copolymer.

Claim 4

The composition according to claim 1 wherein said sequential propylene-ethylene copolymer has a melt flow (ASTM D 1238 Cond. L) between about 4 and 12 dg/min.

Claim 5

The composition according to claim 1 wherein said linear low density ethylene copolymer has a melt index (ASTM D1238 Cond. E) between about 1 and 7 dg/min.

Claim 6

The composition according to claim 1 wherein said linear low density ethylene copolymer has a density between about 0.917 and 0.925 g/cc.

Claim 7

The composition according to claim 1 wherein a nucleating agent is added prior or after visbreaking to improve stiffness and ease of melt processing.

Claim 8

The composition according to claim 1 wherein the peroxide-contacting is accomplished by extruding said propylene polymer in the presence of a peroxide.

Claim 9

The composition according to claim 7 wherein the amount of peroxide employed is between about 150 and 1500 parts by weight per million parts by weight propylene polymer.

Claim 10

The composition according to claim 7 wherein said peroxide is 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane.

Claim 11

The composition according to claim 7 wherein said peroxide-contacting takes place at a temperature between about 190° C. and 260° C.

Claim 12

The composition according to claim 1 wherein said high density polyethylene has a density between about 0.955 and 0.965.

Claim 13

The composition according to claim 1 wherein said high density polyethylene has a density between about 0.955 and 0.965.

Claim 14

A composition having a melt flow between about 5 and about 50 dg/min (ASTM D1238-Condition L), and a high notched impact value, said composition being obtained by first melt blending an impact-improved propylene-ethylene copolymer with a linear low density ethylene copolymer and a high density ethylene homopolymer, and then contacting said blend containing well dispersed polyethylene modifiers with a peroxide during further melt mixing, wherein: (a) said impact-improved propylene-ethylene polymer has a melt flow (ASTM D1238-Condition L) of about 0.5-15 dg/min and an elastomeric propylene-ethylene copolymer content of 5-50% by weight, the copolymer fraction having an ethylene content of 30-95% by weight, which propylene-ethylene polymer is the product of sequential polymerization of propylene and a propylene-ethylene mixture over a titanium halide-containing coordination catalyst; (b) said high density ethylene homopolymer has a density in the range from 0.941 to 0.965 grams per cubic centimeter and a melt index (ASTM D1238-Condition E) in the range from 0 to 20 dg/min; (c) said linear low density ethylene copolymer is the product of random polymerization of ethylene with up to 15 mole percent of at least one C 3 -C 8 alpha olefin monomer over a transition metal-based coordination catalyst and which has a density below 0.935 and a melt index (ASTM D1238-Condition E) not exceeding 16; and (d) said composition comprises 50-90% by weight of said impact-modified propylene polymer, 3-45% by weight of said high density ethylene homopolymer, 3-45% by weight of said linear low density ethylene copolymer, wherein the weight ratio of said high density ethylene homopolymer to said linear low density ethylene copolymer is between 80:20 and 20:80.

Claim 15

A composition having a melt flow between about 5 and about 50 dg/min (ASTM D1238-Condition L), and a high notched impact value, said composition being obtained by first melt blending an impact-improved propylene-ethylene copolymer with a linear low density ethylene copolymer and a high density ethylene homopolymer, and then contacting said blend containing well dispersed polyethylene modifiers with a peroxide during further melt mixing, wherein: (a) said impact-improved propylene-ethylene polymer has a melt flow (ASTM D1238-Condition L) of about 0.5-15 dg/min and an elastomeric propylene-ethylene copolymer content of 5-50% by weight, the copolymer fraction having an ethylene content of 30-95% by weight, which propylene-ethylene polymer is the product of sequential polymerization of propylene and a propylene-ethylene mixture over a titanium halide-containing coordination catalyst; (b) said high density ethylene homopolymer has a density in the range from 0.941 to 0.965 grams per cubic centimeter and a melt index (ASTM D1238-Condition E) in the range from 0 to 20 dg/min; (c) said linear low density ethylene copolymer is the product of random polymerization of ethylene with up to 15 mole percent of at least one C 3 -C 8 alpha olefin monomer over a transition metal-based coordination catalyst and which has a density below 0.935 and a melt index (ASTM D1238-Condition E) not exceeding 16; and (d) said composition comprises 50-90% by weight of said impact-modified propylene polymer, 3-45% by weight of said high density ethylene homopolymer, 3-45% by weight of said linear low density ethylene copolymer, wherein the weight ratio of said high density ethylene homopolymer to said linear low density ethylene copolymer is between 80:20 and 20:80.

Claim 16

The composition according to claim 13 wherein said linear low density ethylene copolymer is an ethylene-1-butene copolymer.

Claim 17

The composition according to claim 13 wherein said sequential propylene-ethylene copolymer has a melt flow (ASTM D 1238 Cond.L) between about 4 and 12 dg/min.

Claim 18

The composition according to claim 13 wherein said linear low density ethylene copolymer has a melt index (ASTM D1238 Cond. E) between about 1 and 7 dg/min.

Claim 19

The composition according to claim 13 wherein said linear low density ethylene copolymer has a density between about 0.917 and 0.925 g/cc.

Claim 20

The composition according to claim 13 wherein a nucleating agent is added prior or after visbreaking to improve stiffness and ease of melt processing.

Claim 21

The composition according to claim 13 wherein the peroxide-contacting is accomplished by extruding said propylene polymer melt blend with polyethylenes in the presence of a peroxide.

Claim 22

The composition according to claim 19 wherein the amount of peroxide employed is between about 150 and 1000 parts by weight per million parts by weight propylene polymer blend with polyethylenes.

Claim 23

The composition according to claim 19 wherein said peroxide is 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane.

Claim 24

The composition according to claim 19 wherein said peroxide-contacting takes place at a temperature between about 190° C. and 260° C.

Claim 25

The composition according to claim 13 wherein said high density polyethylene has a density between about 0.955 and 0.965.

Claim 26

The composition according to claim 13 wherein the peroxide is sufficiently thermally stable such that it can be added with the other components of the composition, and does not decompose to initiate visbreaking until the polyethylene modifiers are well dispersed during melt mixing.

Claim 27

The composition according to claim 24 wherein the peroxide has a one-hour half life for decomposition at a temperature greater than 148° C.

Claim 28

The composition according to claim 24 wherein the peroxide is 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3.

Claim 29

The composition according to claim 1 wherein said linear low density ethylene copolymer has a density in the range from 0.912 to 0.935 g/cc.

Claim 30

The composition according to claim 13 wherein said linear low density ethylene copolymer has a density in the range from 0.912 to 0.935 g/cc.