# US 5,352,534 A · Oriented polyester film > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,352,534 A - Document ID: US5352534A - Status: Granted - Kind: A - Application number: 08/203,923 - Filed: 1994-03-01 - Granted: 1994-10-04 - Earliest claimed: 1992-03-19 - Assignees: Teijin Limited - Inventors: Hisashi Hamano; Masahiro Hosoi; Masanori Nishiyama; Yasuhiro Saeki - Web page: https://patentgrep.com/patent/US5352534A ## CPC - C08J 5/18: Manufacture of films or sheets - C08G 63/185: containing two or more aromatic rings - C08G 63/672: Dicarboxylic acids and dihydroxy compounds - H01B 3/422: {Linear saturated polyesters derived from dicarboxylic acids and dihydroxy compounds} - C08J 2367/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence) - Y10T 428/31786: Of polyester [e.g., alkyd, etc.] - 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) - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS - H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K}) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An oriented polyester film (A) which comprises modified polyethylene-2,6-naphthalenedicarboxylate containing a 4,4'-diphenyldicarboxylic acid component and having a heat of crystallization of 16 to 25.5 Joule/g, and (B) which is biaxially oriented; and an oriented polyester film (A') which comprises modified polyethylene-2,6-naphthalenedicarboxylate containing of a glycol component derived from a compound represented by the following formula, ##STR1## wherein each of n and m is independently a positive number of 1 to 9 as an average, provided that m+n equals 2 to 9 as an average, and having a heat of crystallization of 6 to 20 Joule/g, and (B) which is biaxially oriented. These films are useful as a base film for a magnetic recording tape or as an electric insulation film. ## Claims ### Claim 1 An oriented polyester film: (A') which comprises modified polyethylene-2,6-naphthalenedicarboxylate containing of a glycol component derived from a compound represented by the following formula, ##STR5## wherein each of n and m is independently a positive number of 1 to 9 as an average, provided that m+n equals 2 to 9 as an average, and having a heat of crystallization of 6 to 20 Joule/g, and (B) which is biaxially oriented. ### Claim 2 (depends on 1) The oriented polyester film of claim 1, (C') Which exhibits a heat of fusion of the crystal of 7 to Joule/g. ### Claim 3 (depends on 1) The oriented polyester film of claim 1, which has a thickness of 40 to 350 .mu.m and is used for electric insulation. ### Claim 4 (depends on 1) The oriented polyester film of claim 1, which has a thickness of 4 to 35 .mu.m and is used as a base film for a magnetic recording tape. ### Claim 5 (depends on 4) The oriented polyester film of claim 4, which has a Young's modulus of at least 750 kg/mm.sup.2 in at least one direction of its longitudinal and transverse directions. ### Claim 6 (depends on 1) The oriented polyester film of claim 1, wherein the glycol component derived from the compound represented by the formula in claim 1 is contained in an amount of 0.1 to 2.0 mol% based on a total glycol component content of the modified polyethylene-2,6-naphthalenedicarboxylate. ### Claim 7 (depends on 6) The oriented polyester film of claim 6, wherein an ethylene glycol component is contained in an amount of 98 to 99.9 mol% based on a total glycol component content. ### Claim 8 (depends on 1) The oriented polyester film of claim 1, wherein 2,6-naphthalenedicarboxylic acid component is contained in an amount of at least 90 mol% based on a total acid component of the modified polyethylene-2,6-naphthalenedicarboxylate. ### Claim 9 A magnetic recording tape comprising a magnetic film layer and a base film which comprises modified polyethylene-2,6-naphthalenedicarboxylate containing a 4,4'-diphenyldicarboxylic acid component as a polymerized unit in its polymer chain, in an amount of 1 to 5 mol% based on a total acid component content of the modified polyethylene-2,6-naphthalenedicarboxylate, and having a heat of crystallization of 16 to 25.5 Joule/g, and which is biaxially oriented. ### Claim 10 An electric insulating film having electric insulating properties which comprises modified polyethylene-2,6-naphthalenedicarboxylate containing a 4,4'-diphenyldicarboxylic acid component as a polymerized unit in its polymer chain, in an amount of 1 to 5 mol% based on a total acid component content of the modified polyethylene-2,6-naphthalenedicarboxylate, and having a heat of crystallization of 16 to 25.5 Joule/g, and which is biaxially oriented. ### Claim 11 A magnetic recording tape comprising a magnetic film layer and a base film which comprises modified polyethylene-2,6-naphthalenedicarboxylate containing a glycol component derived from a compound represented by the following formula, ##STR6## wherein each of n and m is independently a positive number of 1 to 9 as an average provided that m+n equals 2 to 9 as an average, and having a heat of crystallization of 6 to 20 Joule/g, and which is biaxially oriented. ### Claim 12 An electric insulating film having electric insulating properties which comprises modified polyethylene-2,6-naphthalenedicarboxylate containing a glycol component derived from a compound represented by the following formula, ##STR7## wherein each of n and m is independently a positive number of 1 to 9 as an average, provided that m+n equals 2 to 9 as an average, and having a heat of crystallization of 6 to 20 Joule/g, and which is biaxially oriented.