# US 9,040,151 B2 · Ultra-stiff coextruded shrink films > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,040,151 B2 - Document ID: US9040151B2 - Status: Granted - Kind: B2 - Application number: 13/669,557 - Filed: 2012-11-06 - Published: 2014-05-08 - Granted: 2015-05-26 - Earliest claimed: 2012-11-06 - Assignees: Dow Global Technologies LLC - Applicants: Dow Global Technologies LLC - Inventors: Martin Pavlik - Web page: https://patentgrep.com/patent/US9040151B2 ## CPC - B32B 7/02: Physical, chemical or physicochemical properties - B32B 27/08: of synthetic resin - B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)} - B32B 2250/242: All polymers belonging to those covered by group B32B27/32 - B32B 2270/00: Resin or rubber layer containing a blend of at least two different polymers - B32B 2307/406: Bright, glossy, shiny surface - B32B 2307/54: Yield strength; Tensile strength - B32B 2307/5825: Tear resistant - B32B 2307/736: Shrinkable - B32B 2439/00: Containers; Receptacles - B32B 2439/02: Open containers - B32B 2439/40: Closed containers - Y10T 428/24992: Density or compression of components - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The present invention generally pertains to multilayer film including four or more discrete layers. The films contain two external layers, an internal stiffening layer and an internal shrink layer. The external layers include linear low density polyethylene resin, the stiffening layer includes polypropylene or a high density polyethylene and the shrink layer includes low density polyethylene. The multilayer films of the present invention have a gloss of at least 62% at 45 degrees, together with a 2% secant tensile modulus greater than 400 MPa. ## Claims ### Claim 1 A multilayer film comprising four or more discrete layers comprising: a. a first and a second external layer, wherein each external layer independently comprises: i. from 60 to 100% by weight of the external layer of a linear low density polyethylene resin characterized by having a melt index in the range of 0.3 to 4 g/10 min and a density in the range of from 0.917 to 0.950 g/cm3, and a MWD of from 3 to 9 and ii. from 0 to 40% by weight of the external layer of a first high pressure low density polyethylene resin characterized by having a melt index in the range of 0.3 to 4 g/10 min and a density in the range of from 0.918 to 0.935 g/cm3; b. at least one internal stiffening layer, wherein the stiffening layer or layers cumulatively comprise at least 20% of the film by weight and wherein each stiffening layer independently comprises: i. from 60 to 100% by weight of the stiffening layer of a stiffening resin selected from the group consisting of 1) a polypropylene resin, wherein said polypropylene resin is selected from the group consisting of homopolymer polypropylene and a propylene random copolymer derived from more than 90% by weight propylene and up to 10% by weight ethylene or one or more alpha olefins having 4 to 10 carbon atoms, wherein the polypropylene resin is characterized by having a melt flow rate in the range of 0.1 to 2 g/10 min; and 2) a first linear high density polyethylene resin characterized by having a melt index in the range of 0.25 to 4 g/10 min and a density in the range of from 0.935 to 0.975 g/cm3; and 3) blends thereof, and; c. at least one internal shrink layer, wherein each shrink layer independently comprises: i. from 50 to 100% by weight of the shrink layer of a second high pressure low density polyethylene resin characterized by having a melt index in the range of 0.2 to 1 g/10 min and a density in the range of from 0.917 to 0.935 g/cm3;and ii. from 0 to 50% of a second linear high density polyethylene resin characterized by having a melt index in the range of 0.2 to 4 g/10 min and a density in the range of from 0.930 to 0.975 g/cm3; wherein the multilayer film is characterized by having a gloss of at least 60% at 45 degrees, together with a 2% secant tensile modulus greater than 400 MPa in the machine direction, the cross direction or both the machine direction and the cross direction. ### Claim 2 (depends on 1) The multilayer film of claim 1 where the film comprises at least 5 layers, two of which are stiffening layers. ### Claim 3 (depends on 2) The multilayer film of claim 2 wherein each external layer comprises the same material and each stiffening layer comprises the same material. ### Claim 4 (depends on 1) The multilayer film of claim 1 wherein the first high pressure low density polyethylene resin and the second high pressure low density polyethylene resin are the same. ### Claim 5 (depends on 1) The multilayer film of claim 1 wherein the first high pressure low density polyethylene resin in the external layer has a melt index in the range of 0.8 to 1.5 g/10 min. ### Claim 6 (depends on 1) The multilayer film of claim 1 wherein the high pressure low density polyethylene resin in the external layer has a density in the range of from 0.923 to 0.928 g/cm3. ### Claim 7 (depends on 1) The multilayer film of claim 1 wherein the resin used in each internal stiffening layer comprises only the stiffening resin. ### Claim 8 (depends on 1) The multilayer film of claim 1 wherein the polypropylene has a melt flow rate in the range of from 0.5 to 1.5 g/10 min. ### Claim 9 (depends on 1) The multilayer film of claim 1 wherein the resin used in each internal shrink layer comprises only the second high pressure low density polyethylene. ### Claim 10 (depends on 1) The multilayer film of claim 1 wherein the multilayer film has a total thickness of less than or equal to 35 microns. ### Claim 11 (depends on 1) The multilayer film of claim 1 wherein each external layer comprises 5 to 25% of the total thickness of the film. ### Claim 12 (depends on 1) The multilayer film of claim 1 wherein the stiffening layer or layers collectively comprise from 20 to 60% of the total thickness of the film. ### Claim 13 (depends on 1) The multilayer film of claim 1 wherein the shrink layer or layers collectively comprise from 30 to 70% of the total thickness of the film. ### Claim 14 (depends on 1) The multilayer film of claim 1 further characterized by having a total haze less than 10%. ### Claim 15 (depends on 1) The multilayer film of claim 1 further characterized by having an average shrink in the machine direction of from 40 to 90%. ### Claim 16 (depends on 1) The multilayer film of claim 1 further characterized by having an average shrink in the cross direction of from 0 to 25%. ### Claim 17 (depends on 1) The multilayer film of claim 1 further characterized by having a puncture resistance of at least 2 J/cm3.