# US 8,771,569 B2 · Polyethylene film and method for the manufacture thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,569 B2 - Document ID: US8771569B2 - Status: Granted - Kind: B2 - Application number: 13/143,744 - Filed: 2010-01-06 - Published: 2011-11-03 - Granted: 2014-07-08 - Earliest claimed: 2009-01-09 - Assignees: Teijin Aramid B.V. - Applicants: Joris Eem Van Der; Johannes Bos; Anton Peter De Weijer; Sanjay Rastogi; Gerwin Elderman - Inventors: Joris Eem Van Der; Johannes Bos; Anton Peter De Weijer; Sanjay Rastogi; Gerwin Elderman - Web page: https://patentgrep.com/patent/US8771569B2 ## CPC - C08J 5/18: Manufacture of films or sheets - C08J 2323/06: Polyethene - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) ## Abstract The present invention pertains to a polyethylene film and a process for manufacturing such film. The polyethylene film may have a ratio between the strength in a first direction in the film plane and the strength in a second direction in the film plane perpendicular to the first direction in the range of 0.1-10:1, the strength in at least one direction being at least 0.2 Gpa. The process for manufacturing a polyethylene film may have a starting UHMWPE polymer with an average molecular weight of at least 500,000 grams/mole, an elastic shear modulus determined directly after melting at 160° C. of at most 1.4 MPa, and a Mw/Mn ratio of at most 6 to a solvent-free compacting process and a stretching process under such conditions that at no point during the process the temperature of the intermediate polymer film is raised to a value above its melting point. ## Claims ### Claim 1 A polyethylene film comprising polyethylene and having a ratio between a strength in a first direction in the film plane and a strength in a second direction in the film plane perpendicular to the first direction in a range of about 1:10 to 10:1, the strength in at least one direction in the film plane being at least 0.2 GPa, wherein the polyethylene has a weight average molecular weight (Mw) of at least 500,000 grams/mole and a Mw/Mn ratio of at most 6. ### Claim 2 (depends on 1) The polyethylene film according to claim 1, wherein the ratio between the strength in the first direction in the film plane and the strength in the second direction in the film plane perpendicular to the first direction is in the range of 2:10 to 5:1. ### Claim 3 (depends on 1) The polyethylene film according to claim 1, wherein the strength in the first direction is at least 0.2 GPa, while the strength in the second direction in the film plane perpendicular to the first direction is at least 0.2 GPa. ### Claim 4 (depends on 1) The polyethylene film according to claim 1, wherein the strength of the film, in at least one direction in the film plane, is at least 0.3 GPa. ### Claim 5 (depends on 1) The polyethylene film according to claim 1, wherein the polyethylene has a weight average molecular weight (Mw) of between 1×106 grams/mole and 1×108 grams/mole. ### Claim 6 (depends on 1) The polyethylene film according to claim 1, wherein the polyethylene has a Mw/Mn ratio of at most 4. ### Claim 7 (depends on 1) The polyethylene film according to claim 1, wherein the polyethylene film has a thickness of at most 15 microns. ### Claim 8 (depends on 1) The polyethylene film according to claim 1, further having a uniplanar orientation parameter Φ of at least 2. ### Claim 9 A method of manufacturing a UHMWPE film, comprising: subjecting a starting UHMWPE polymer having a weight average molecular weight (Mw) of at least 500,000 grams/mole, an elastic shear modulus determined directly after melting at 160° C. of at most 1.4 MPa, and a Mw/Mn ratio of at most 6, to a solvent-free compacting process and a stretching process under such conditions that at no point during the compacting process and the stretching process is a temperature of the polymer and of an intermediate polymer film raised to a value above their melting point, wherein during the stretching process a force is applied onto the intermediate polymer film during a stretching process, in a first direction and in a second direction which is perpendicular to the first direction. ### Claim 10 (depends on 9) The method according to claim 9, wherein the force applied onto the intermediate polymer film in a first direction is applied in a machine direction, and the force applied in the second direction is applied in a direction perpendicular to the machine direction. ### Claim 11 (depends on 9) The method according to claim 9 wherein the stretching process encompasses at least two stretching steps. ### Claim 12 (depends on 9) The method according to claim 9, wherein the stretching process comprises subjecting the intermediate polymer film to a force in the first direction during all stretching steps, and to a force in the second direction during at least one stretching step. ### Claim 13 (depends on 9) The method according to claim 9, wherein a total stretching ratio, defined as the area of the cross-section of the compacted mothersheet divided by the cross-section of the drawn film produced from the compacted mothersheet, is applied which is at least 40. ### Claim 14 (depends on 9) The method according claim 9, wherein a ratio between a stretching ratio applied in the first direction and a stretching ratio applied in the second direction perpendicular to the first direction in the film plane is in the range of 1:10 to 10:1. ### Claim 15 (depends on 9) The method according to claim 9, wherein the UHMWPE film is in the form of at least of a membrane, packaging, or a product for ballistic applications. ### Claim 16 (depends on 1) The polyethylene film according to claim 1, wherein the strength in the first direction is at least 0.5 GPa, while the strength in the second direction in the film plane perpendicular to the first direction is at least 0.2 GPa. ### Claim 17 (depends on 1) The polyethylene film according to claim 1, wherein the strength in the first direction is at least 1 GPa, while the strength in the second direction in the film plane perpendicular to the first direction is at least 0.2 GPa. ### Claim 18 (depends on 1) The polyethylene film according to claim 1, wherein the strength of the film, in at least one direction in the film plane, is at least 0.5 GPa. ### Claim 19 (depends on 1) The polyethylene film according to claim 1, wherein the strength of the film, in at least one direction in the film plane, is at least 1 GPa. ### Claim 20 (depends on 1) The polyethylene film according to claim 1, wherein the polyethylene has a Mw/Mn ratio of at most 2. ### Claim 21 (depends on 1) The polyethylene film according to claim 1, wherein the polyethylene film has a thickness of at most 7 microns. ### Claim 22 (depends on 9) The method according to claim 9, wherein a total stretching ratio, defined as the area of the cross-section of the compacted mothersheet divided by the cross-section of the drawn film produced from the compacted mothersheet, is applied which is at least 100. ### Claim 23 (depends on 9) The method according to claim 9, wherein a total stretching ratio, defined as the area of the cross-section of the compacted mothersheet divided by the cross-section of the drawn film produced from the compacted mothersheet, is applied which is at least 160. ### Claim 24 (depends on 9) The method according claim 9, wherein a ratio between a stretching ratio applied in the first direction and a stretching ratio applied in the second direction perpendicular to the first direction in the film plane is in the range of 5:10 to 2:1.