# US 8,772,419 B2 · Polyester films with low thermal expansion and methods for manufacturing the same

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- Number: US 8,772,419 B2
- Document ID: US8772419B2
- Status: Granted
- Kind: B2
- Application number: 13/494,660
- Filed: 2012-06-12
- Published: 2013-06-13
- Granted: 2014-07-08
- Earliest claimed: 2011-12-13
- Assignees: Industrial Technology Research Institute
- Applicants: Li-Cheng Jheng; Jrjeng Ruan; Ming-Tsong Leu; Kuo-Chen Shih; Jyh-Horng Wu; Cheng-Hsing Fan
- Inventors: Li-Cheng Jheng; Jrjeng Ruan; Ming-Tsong Leu; Kuo-Chen Shih; Jyh-Horng Wu; Cheng-Hsing Fan
- Web page: https://patentgrep.com/patent/US8772419B2

## CPC

- C08L 67/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds (C08L67/06 takes precedence)
- B29C 48/0018: {combined with shaping by orienting, stretching or shrinking, e.g. film blowing (B29C48/0017 takes precedence)}
- B29C 48/92: Measuring, controlling or regulating
- B29C 55/143: {firstly parallel to the direction of feed and then transversely thereto}
- B29C 55/16: simultaneously
- C08G 63/189: containing a naphthalene ring
- C08G 63/199: Acids or hydroxy compounds containing cycloaliphatic rings
- C08J 5/18: Manufacture of films or sheets
- B29C 48/022: {characterised by the choice of material}
- B29C 48/08: flexible, e.g. films
- B29C 2948/9258: Velocity
- B29C 2948/92704: Temperature
- B29K 2267/00: Use of polyesters {or derivatives thereof} as reinforcement
- B29K 2995/0012: having particular thermal properties
- B29K 2995/0053: bi-axially
- C08J 2367/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence)
- C08J 2467/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds (C08J2467/06 takes precedence)
- C08L 2205/02: containing two or more polymers of the same C08L -group
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- 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)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- 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)
- 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

## Abstract

Disclosed is a method for manufacturing a polyester film with low thermal expansion. 95 wt % to 55 wt % of crystalline polyester and 5 wt % to 45 wt % of amorphous polyester are mixed. The blend is then melt extruded to form a sheet. The sheet is then biaxially stretched to obtain a film. The biaxially stretched film is then treated with a heat-setting procedure.

## Claims

### Claim 1

A polyester film with low thermal expansion, consisting of:
95 wt % to 55 wt % of poly(ethylene-2,6-naphthalate) copolymerized of dimethyl-2,6-naphthalene dicaboxylate and ethylene glycol as a crystalline polyester; and
5 wt % to 45 wt % of cyclohexanedimethanol-modified poly(ethylene-terephthalate) copolymerized of terephthalic acid, ethylene glycol, and cyclohexanedimethanol, wherein the ethylene glycol and the cyclohexanedimethanol have a molar ratio of 50:50 to 80:20, and the cyclohexanedimethanol comprises 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, or combinations thereof as an amorphous polyester,
wherein the poly(ethylene-2,6-naphthalate) and the cyclohexanedimethanol-modified poly(ethylene-terephthalate) are mixed with each other.

### Claim 2 (depends on 1)

The polyester film with low thermal expansion as claimed in claim 1, having a thermal expansion coefficient of 1 ppm/° C. to 12.4 ppm/° C.

### Claim 3

A method of manufacturing a polyester film with low thermal expansion, comprising:
drying and then mixing 95 wt % to 55 wt % of crystalline polyester and 5 wt % to 45 wt % of amorphous polyester to form a blend;
melt extruding the blend to form a sheet;
biaxial stretching the sheet to form a film; and
heat-setting the film;
wherein the crystalline polyester is poly(ethylene-2,6-naphthalate) copolymerized of dimethyl-2,6-naphthalene dicaboxylate and ethylene glycol; and
wherein the amorphous polyester is cyclohexanedimethanol-modified poly(ethylene-terephthalate) copolymerized of terephthalic acid, ethylene glycol, and cyclohexanedimethanol, wherein the ethylene glycol and the cyclohexanedimethanol have a molar ratio of 50:50 to 80:20, and the cyclohexanedimethanol comprises 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, or combinations thereof.

### Claim 4 (depends on 3)

The method as claimed in claim 3, wherein the step of biaxial stretching the sheet to form the film is performed by a stretching speed of 1%/sec to 40%/sec.

### Claim 5 (depends on 3)

The method as claimed in claim 3, wherein the step of biaxial stretching the sheet to form the film is performed with a stretching ratio greater than 3.5×3.5.

### Claim 6 (depends on 3)

The method as claimed in claim 3, wherein the step of biaxial stretching the sheet to form the film is performed with a processing temperature of 120° C. to 160° C.