# US 8,784,983 B2 · Expanded porous polytetrafluoroethylene film-laminated sheet, and gasket composed of said sheet > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,784,983 B2 - Document ID: US8784983B2 - Status: Granted - Kind: B2 - Application number: 12/678,551 - Filed: 2008-09-19 - Published: 2010-11-11 - Granted: 2014-07-22 - Earliest claimed: 2007-09-20 - Assignees: W. L. Gore & Associates, Inc. - Applicants: Hirokaze Hisano; Shinichi Urakami - Inventors: Hirokaze Hisano; Shinichi Urakami - Web page: https://patentgrep.com/patent/US8784983B2 ## CPC - F16J 15/102: {characterised by material} - B29C 55/005: {characterised by the choice of materials} - B32B 7/10: at least one layer having inter-reactive properties - B32B 7/12: using interposed adhesives or interposed materials with bonding properties - B32B 27/08: of synthetic resin - B32B 27/14: next to a particulate layer - B32B 27/322: {comprising halogenated polyolefins, e.g. PTFE} - F16J 15/3236: with at least one lip for each surface, e.g. U-cup packings - B29K 2027/18: PTFE, i.e. polytetrafluoroethylene {, e.g. ePTFE, i.e. expanded polytetrafluoroethylene} - B29K 2105/04: cellular or porous - B29L 2031/265: {Packings, Gaskets} - B32B 2264/0257: Polyolefin particles, e.g. polyethylene or polypropylene homopolymers or ethylene-propylene copolymers - B32B 2307/304: Insulating - B32B 2307/518: bi-axially - B32B 2307/714: Inert, i.e. inert to chemical degradation, corrosion - B32B 2307/72: Density - B32B 2581/00: Seals; Sealing equipment; Gaskets - Y10T 156/10: Methods of surface bonding and/or assembly therefor - Y10T 428/249978: Voids specified as micro - Y10T 428/249979: Specified thickness of void-containing component [absolute or relative] or numerical cell dimension - Y10T 428/249981: Plural void-containing components - Y10T 428/249991: Synthetic resin or natural rubbers - Y10T 428/249992: Linear or thermoplastic - F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS - B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The laminated sheet of this invention is a sheet including expanded porous polytetrafluoroethylene films laminated by thermal compression bonding, wherein the sheet has a specific surface area of 9.0 m2/g or larger and a density of from 0.4 g/cm3 to lower than 0.75 g/cm3, thereby making it possible to improve both the creep resistance and the adhesiveness between the films of the expanded porous PTFE film-laminated sheet. ## Claims ### Claim 1 A laminated sheet comprising laminated expanded porous polytetrafluoroethylene films, wherein the sheet has a specific surface area of 9.0 m2/g or higher and a density of from 0.4 g/cm3 to lower than 0.75 g/cm3, wherein the laminated sheet has a 180-degree peeling strength of 0.20 N/mm or higher between the films at the center in the thickness direction of the sheet and wherein the laminated sheet has a stress-relaxation rate of 45% or lower after 1 hour when compressed at a surface pressure of 50 MPa, and wherein the laminated sheet has a thickness of from about 0.1 mm to about 300 mm. ### Claim 2 (depends on 1) The laminated sheet of claim 1, wherein the sheet has a matrix strength of 120 MPa or higher in at least one direction among in-plane directions of the sheet and has a ratio of matrix strengths of from 0.5 to 2 in two orthogonal directions among in-plane directions of the sheet. ### Claim 3 (depends on 1) The laminated sheet of claim 1, further comprising a fluororesin layer having a density of 1.6 g/cm3 or higher on a surface, or as an intermediate layer, of the laminated sheet. ### Claim 4 (depends on 1) The laminated sheet of claim 1, wherein at least one of the expanded porous polytetrafluoroethylene films is produced by extrusion of a polytetrafluoroethylene powder at a reduction ratio of 100 or higher to form a tape, expanding the tape at an expansion speed of 100%/sec or higher and at an expansion ratio of 3 times or higher in a machine direction of the tape, and then expanding the tape at an expansion speed of 50%/sec or higher and at an expansion ratio of 10 times or higher in a transverse direction of the tape to obtain a film. ### Claim 5 (depends on 4) A gasket comprising the laminated sheet of claim 4, and having an irregularity-fitting portion for following an irregularity on a seal face. ### Claim 6 (depends on 4) The laminated sheet of claim 4, wherein the sheet has a matrix strength of 120 MPa or higher in at least one direction among in-plane directions of the sheet and has a ratio of matrix strengths of from 0.5 to 2 in two orthogonal directions among in-plane directions of the sheet. ### Claim 7 (depends on 1) The laminated sheet of claim 1, wherein the expanded porous polytetrafluoroethylene films are laminated by thermal compression bonding. ### Claim 8 (depends on 1) The laminated sheet of claim 1, wherein the laminated sheet has a thickness of from about 0.5 mm to about 20 mm. ### Claim 9 (depends on 1) The laminated sheet of claim 1, wherein the density of the sheet is from about 0.5 g/cm3 to about 0.70 g/cm3. ### Claim 10 (depends on 1) The laminated sheet of claim 1, wherein the sheet has a specific surface area of 15 m2/g or lower. ### Claim 11 A laminated sheet comprising expanded porous polytetrafluoroethylene films laminated by thermal compression bonding, wherein the sheet has a specific surface area of 9.0 m2/g or higher and a density of from 0.4 g/cm3 to lower than 0.75 g/cm3, wherein the laminated sheet has a 180-degree peeling strength of 0.20 N/mm or higher between the films at the center in the thickness direction of the sheet, wherein the sheet has a stress-relaxation rate of 45% or lower after 1 hour when compressed at a surface pressure of 50 MPa, and wherein the laminated sheet has a thickness from about 0.1 mm to about 300 mm. ### Claim 12 (depends on 11) The laminated sheet of claim 11, wherein the sheet has a specific surface area of 10.0 m2/g or higher. ### Claim 13 (depends on 11) The laminated sheet of claim 11, wherein the sheet has a specific surface area of 15 m2/g or lower. ### Claim 14 (depends on 11) The laminated sheet of claim 11, wherein the sheet has a matrix strength of 120 MPa or higher in at least one direction among in-plane directions of the sheet and has a ratio of matrix strengths of from 0.5 to 2 in two orthogonal directions among in-plane directions of the sheet. ### Claim 15 A laminated sheet comprising expanded porous polytetrafluoroethylene films laminated by thermal compression bonding, wherein the sheet has a specific surface area of from 9.0 m2/g to 15 m2/g and a density of from 0.4 g/cm3 to lower than 0.75 g/cm3, wherein the laminated sheet has a 180-degree peeling strength of 0.20 N/mm or higher between the films at the center in the thickness direction of the sheet, wherein the laminated sheet has a stress-relaxation rate of 45% or lower after 1 hour when compressed at a surface pressure of 50 MPa, and wherein the laminated sheet has a thickness of from about 0.1 mm to about 300 mm.