Process for making film from low density ethylene hydrocarbon copolymer

Claim 2

A process for forming blown tubular film essentially free of melt fracture from an extrudate formed from molten ethylene hydrocarbon copolymer, said copolymer having been made from ≧90 mol percent of ethylene and ≦10 mol percent of at least one C 3 to C 8 alpha olefin monomer with a transition metal based catalyst and having a narrow molecular weight distribution and a melt index of about ≧0.1 to about ≦5.0 and being susceptible to melt fracture in blown tubular film form when extruded into such form through an extrusion die having a die gap of 15 to ≦45 mils, which comprises extruding said copolymer into such form through an extrusion die having a die gap of greater than about 50 mils and at a drawdown ratio of greater than about 2 to less than about 250.

Claim 3

A process as in claim 1 in which said copolymer has a melt index of about >0.5 to ≦4.0.

Claim 4

A process as in claim 1 in which said copolymer has a density of about ≧0.912 to ≦0.940.

Claim 5

A process as in claim 3 in which said copolymer has a molecular weight distribution of about ≧2.7 to ≦3.6 and a total unsaturation content of about ≧0.1 to ≦0.3 C═C/1000 C atoms.

Claim 6

A process as in claim 3 in which said copolymer has a melt flow ratio of about ≧22 to ≦36 and a total unsaturation content of about ≧0.1 to ≦0.3 C═C/1000 C atoms.

Claim 7

A process as in claim 1 in which said copolymer has a molecular weight distribution of about ≧2.7 to ≦3.6.

Claim 8

A process as in claim 6 in which the alpha olefin comprises butene-1.

Claim 9

A process as in claim 7 in which the die gap is greater than about 50 to less than about 120 mils.

Claim 10

A process as in claim 8 in which said gap is greater than about 50 to less than about 90 mils.

Claim 11

A process as in claim 1 in which said film is formed at a drawdown ratio of about 25 to less than about 150.

Claim 12

A process as in claim 1 in which said copolymer is formed into film having a thickness greater than about 0.1 to about 20 mils.

Claim 13

A process as in claim 11 in which said film has a thickness of greater than about 0.1 to about 6.0 mils.

Claim 14

A process as in claim 12 in which said film has an ultimate elongation of greater than about 400 percent.

Claim 15

A process as in claim 12 in which said film has a puncture resistance of greater than about 7.0 in-lb./mil.

Claim 16

A process as in claim 12 in which said film has a tensile impact strength of greater than about 400 to about 2000 ft.-lbs./in 3 .

Claim 17

A process as in claim 12 in which said film has a tensile strength of greater than about 2000 to about 7000 psi.

Claim 18

A process as in claim 1 in which said film is formed from a composition comprising about 99 to 80 weight percent of said ethylene hydrocarbon copolymer and, about 1 to 20 weight percent of high pressure low density of polyethylene having a melt index of about 0.2 to about 5.0.

Claim 19

A process as in claim 17 in which said composition comprises about 2 to about 12 weight percent of said high pressure low density of polyethylene.

Claim 20

A process as in claim 18 in which said high pressure low density polyethylene has a melt index of about 0.2 to about 5.0.

Claim 21

A process as in claim 18 in which said copolymer has a melt flow ratio of about ≧22 to ≦36 and a total unsaturation content of about ≧0.1 to ≦0.3 C═C/1000 C atoms.

Claim 22

A process as in claim 20 in which said copolymer has a molecular weight distribution of about ≧2.7 to ≦3.6.

Claim 23

A process as in claim 21 in which the alpha olefin comprises butene-1.

Claim 24

A process as in claim 22 in which the die gap is greater than about 50 mils to less than about 120 mils.

Claim 25

A process as in claim 23 in which said die gap is greater than about 50 mils to less than about 90 mils.

Claim 26

A process as in claim 1 wherein the extruded copolymer is cooled to form a frost line providing improved optical properties in the film product according to the following relationships: 45° specular gloss=336.4 φ .sup.-0.664 wherein φ is a cooling rate parameter φ=τ (MI) 0 .29 [(Tm-Tc)/Tm] -1 Tc=resin crystallization temp. (K°) Tm=compound temp. (K°) MI=resin melt index (grams/10 min.) τ=residence time of extrudate between the die and the frost line (sec.), and wherein τ is calculated assuming, that to a first approximation, extrudate extension between the die and the frost line height is a constant strain rate deformation, wherein ##EQU2## where FLH=frost line height (cm.) V 1 =linear nip roll velocity (cm/sec) V 0 =average linear extrudate velocity at the die exit (cm/sec) and is calculated as V.sub.0 =Q/ρmπDG where Q=extruder output rate (grams/sec) ρm=melt density (grams/cm 3 ) D=die diameter (cm) and G=die gap (cm).