# US 5,707,719 A · Oriented film including polystyrene polymer having syndiotactic configuration > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,707,719 A - Document ID: US5707719A - Status: Granted - Kind: A - Application number: 08/654,583 - Filed: 1996-05-29 - Granted: 1998-01-13 - Earliest claimed: 1995-05-29 - Assignees: Toyo Boseki Kabushiki Kaisha - Inventors: Tomonori Yoshinaga; Naonobu Oda; Tadashi Okudaira - Web page: https://patentgrep.com/patent/US5707719A ## CPC - B29C 55/14: successively - B29D 7/01: Films or sheets - B29K 2025/00: Use of polymers of vinyl-aromatic compounds {or derivatives thereof} as moulding material - Y10S 428/91: Product with molecular orientation - Y10T 428/268: Monolayer with structurally defined element - Y10T 428/269: including synthetic resin or polymer layer or component - 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) - B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00) - 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 - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An oriented polystyrene film including a polystyrene polymer having a syndiotactic configuration, the film having a thickness of 25 .mu.m or more, and a rectangular sample of the film having a value C expressed by equation (I) of 0.007 or less: ##EQU1## wherein A.sub.max is obtained by designating four squares respectively in four apices of the rectangular sample, each square having sides of 100 mm in length, and setting an orientation direction of molecules of a first square to 0.degree., A.sub.max being an absolute value of a maximum angle among angles defined by the orientation direction of molecules of the first square and an orientation direction of molecules of each of the other three squares, R is expressed by equation (II) but is defined as 1 when exceeding 1: R=D/1000 (II), and D is a distance (mm) between a center of gravity of the first square and a center of gravity of the square having the orientation direction which defines A.sub.max with the first square, and HS.sub.max is a size change ratio of a square sample which is cut from the rectangular sample and dry-heated at a temperature of 150.degree. C. for 30 minutes, the square sample being designated in an apex of the rectangular sample and having sides of 100 mm in length. ## Claims ### Claim 1 An orineted polystyrene film including a polystyrene polymer having a syndiotactic configuration, the film having a thickness of 25 .mu.m or more, and a rectangular sample of the film having a value C expressed by equation (I) of 0.007 or less: ##EQU8## wherein the rectangular sample is obtainable from (A) or (B): (A) a rolled film extending in a longitudinal direction and having a width in a width direction perpendicular to the longitudinal direction, two sides of the rectangular sample in sample in the longitudinal direction of the film each being 1,000 mm in length and the other two sides of the rectangular sample each having a size equal to the width of the film; or (B) a sheet of any shape, the rectangular sample constituting an inscribed rectangle having an area larger than any other inscribed rectangle, wherein A.sub.max is obtained by designating four squares respectively in four apices of the rectangular sample, each square having sides of 100 mm in length, and setting an orientation direction of molecules of a first square to 0.degree., A.sub.max being an absolute value of a maximum angle among angles defined by the orientation direction of molecules of the first square and an orientation direction of molecules of each of the other three squares, R is expressed by equation (II) but is defined as 1 when exceeding 1: R=D/1000 (II) D is a distance (mm) between a center of gravity of the first square and a center of gravity of the square having the orientation direction which defines A.sub.max with the first square, and HS.sub.max is a size change ratio of a square sample which is cut from the rectangular sample and dry-heated at a temperature of 150.degree. C. for 30 minutes, the square sample being designated in an apex of the rectangular sample and having sides of 100 mm in length. ### Claim 2 (depends on 1) An oriented polystyrene film according to claim 1; wherein A.sub.max is 21.degree. or less. ### Claim 3 (depends on 1) An oriented polystyrene film according to claim 1, wherein an absolute value of HS.sub.max is 0.03 or less. ### Claim 4 An oriented polystyrene film comprising a polystyrene polymer having a syndiotactic configuration, the oriented polystyrene film having a haze of 1% or less and a planar orientation degree .DELTA.P expressed by equation (III) of 0.06 to -0.04: ##EQU9## where N.sub.x is a refractive index of the film in a longitudinal direction, N.sub.y is a refractive index of the film in a width direction, and N.sub.z is a refractive index of the film in a thickness direction. ### Claim 5 (depends on 4) An oriented polystyrene film according to claim 4, having a thermal shrinkage ratio of 2% or less when heated at a temperature of 150.degree. C. for 30 minutes. ### Claim 6 (depends on 4) An oriented polystyrene film according to claim 4, having a thickness of 25 .mu.m or more.