Process for manufacturing high clarity film containing elastomers

Claim 2

A process for the manufacture of elastomeric film which comprises (a) extruding a molten blend of 10 to 85 wt. % of an elastomer and a 90 to 15 wt..% of polyolefin selected from homopolymers and copolymers of propylene and homopolymers and copolymers of ethylene having short chain branching no less than 10 branches per 1000 carbon atoms to form a web, (b) passing the web at a temperature above its softening point.through the nip of counterrotating rollers, one of said rollers being a mirror finish chill roll and the other roller being a resilient roller having a highly glossy rubber surface, and (c) cooling the-blend to produce a film having a haze value below 30%.

Claim 3

A process as defined in claim 1 wherein the highly glossy rubber surface imparts a gloss (at 60°) of at least 40 to one film surface.

Claim 4

The process as defined in claim 1 or 2 wherein the elastomer comprises no more than 70 wt. % of the blend.

Claim 5

The process as defined in claim 1, 2 or 3 wherein the glossy rubber surface is silicone rubber having a Shore A hardness of from 65 to 95.

Claim 6

The process as defined in any one of claims 1-4 wherein the blend comprises from 20 to 70 wt. % of an elastomer selected from EPR and EPDM and the polyolefin comprises from 80 to 30 wt. % of a homopolymer or copolymer of propylene or ethylene or blends thereof.

Claim 7

The process as defined in claim 5 wherein the polyolefin is a blend of crystalline polypropylene and linear low density polyethylene (LLDPE).

Claim 8

The process as defined in claim 6 wherein polypropylene comprises the major weight portion of the polyolefin blend.

Claim 9

The process as defined in any one of claims 1-7 and further comprising air cooling of the melt in advance of the roller nip.

Claim 10

A process for the manufacture of film comprising (a) extruding a molten blend of a polymer blend comprising 20 to 50 wt. % of an elastomer polymer and 50 to 80 wt. % of a polyolefin comprising crystalline polypropylene and LLDPE, or blends of these, to form a molten web (b) passing the web at a temperature above its softening point through the nip of counterrotating rollers, one of said rollers having a high gloss silicone rubber surface for imparting a gloss of at least 60 to the web surface contacted thereby, and the other surface having a polished metal surface for imparting a gloss (60°) of at least 50 to the web surface contacted thereby, forming a film having a thickness no greater than 200 microns; (c) cooling the web to produce a film having a haze less than 15%.

Claim 11

A process for the manufacture of film comprising (a) extruding a molten blend of a polymer blend comprising 20 to 50 wt. % of an elastomer polymer and 50 to 80 wt. % of a polyolefin comprising crystalline polypropylene and LLDPE, or blends of these, to form a molten web (b) passing the web at a temperature above its softening point through the nip of counterrotating rollers, one of said rollers having a high gloss silicone rubber surface for imparting a gloss of at least 60 to the web surface contacted thereby, and the other surface having a polished metal surface for imparting a gloss (60°) of at least 50 to the web surface contacted thereby, forming a film having a thickness no greater than 200 microns; (c) cooling the web to produce a film having a haze less than 15%.

Claim 12

The process of claim 9 which is carried out at a film line speed of at least 10 metres per minute.

Claim 13

The film prepared by the process of claim 1 and having the following properties: (a) haze of less than 30%, (b) MD tear greater than 4 g/micron, and (c) gloss (60°) greater than 40.

Claim 14

The film prepared by the process of claim 1 and having the following properties: (a) thickness of 125 micron or less, (b) haze of less than 15%, (c) MD tensile greater than 27 MPa, (d) MD tear greater than 4 g/micron, and (e) gloss (60°) greater than 60.

Claim 15

The use of film according to claim 11 or 12, or film manufactured by the process according to any one of claims 1 - 10, in medical packaging applications.

Claim 16

Medical packaging or packages which comprises film according to claim 11 or 12 or film manufactured by the process according to any one of claims 1 - 10.