# US 11,298,927 B2 · White polyester film, laminate, and packaging bag

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- Number: US 11,298,927 B2
- Document ID: US11298927B2
- Status: Granted
- Kind: B2
- Application number: 16/320,475
- Filed: 2017-07-24
- Published: 2020-01-23
- Granted: 2022-04-12
- Earliest claimed: 2016-07-27
- Assignees: Toyobo Co., Ltd.
- Applicants: Toyobo Co., Ltd.
- Inventors: Shintaro Ishimaru; Masayuki Haruta
- Web page: https://patentgrep.com/patent/US11298927B2

## CPC

- B32B 27/36: comprising polyesters
- B65D 81/30: by excluding light or other outside radiation (wrappers B65D65/16)
- B32B 5/18: characterised by features of a layer {of} foamed material
- B32B 27/065: {of foam}
- B32B 27/16: specially treated, e.g. irradiated
- B32B 27/18: characterised by the use of special additives
- B32B 27/20: using fillers, pigments, thixotroping agents
- B65D 65/40: Applications of laminates for particular packaging purposes {(B65D1/0215, B65D1/28, B65D3/22, B65D5/0281, B65D5/563, B65D9/30, B65D29/02, B65D31/02, B65D75/26, B65D77/2024, B65D81/1275, B65D81/3811, B65D81/3823, B65D81/3834, B65D81/3846, B65D81/3858, B65D81/3874, B65D81/3886, B65D81/3897 take precedence; laminates per se or laminated packages characterised by the composition or)}
- C08G 63/181: Acids containing aromatic rings
- B32B 2250/03: 3 layers
- B32B 2264/0214: Particles made of materials belonging to B32B27/00
- B32B 2264/0235: Aromatic vinyl resin, e.g. styrenic (co)polymers
- B32B 2264/025: Acrylic resin particles, e.g. polymethyl methacrylate or ethylene-acrylate copolymers
- B32B 2264/102: Oxide or hydroxide
- B32B 2264/104: Oxysalt, e.g. carbonate, sulfate, phosphate or nitrate particles
- B32B 2266/0214: Materials belonging to B32B27/00
- B32B 2266/0228: Aromatic vinyl resin, e.g. styrenic (co)polymers
- B32B 2266/0242: Acrylic resin
- B32B 2266/025: Polyolefin
- B32B 2266/0264: Polyester
- B32B 2307/30: having particular thermal properties
- B32B 2307/31: Heat sealable
- B32B 2307/402: Coloured
- B32B 2307/54: Yield strength; Tensile strength
- B32B 2307/72: Density
- B32B 2307/732: Dimensional properties
- B32B 2307/736: Shrinkable
- B32B 2307/748: Releasability
- B32B 2439/46: Bags
- B32B 2439/70: Food packaging
- B32B 2439/80: Medical packaging
- B32B 2553/00: Packaging equipment or accessories not otherwise provided for
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B65D: CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS

## Abstract

The invention provides a white polyester film formed with a polyester resin whose main constituent is ethylene terephthalate, and (1) the film has at least two or more layers, and has at least one white layer and at least one heat sealing layer, wherein at least one of the film surfaces is the heat sealing layer, and the film satisfies the prescribed requirements of (2) the peeling strength of the heat sealing layers, (3) the difference in reversing heat capacity between at a lower and a higher temperature than a glass transition temperature of the heat sealing layer, (4) the heat shrinkage in both a longitudinal and width direction when treated in hot water at 80° C. for 10 seconds, (5) the total light transmittance, and (6) the apparent specific gravity.

## Claims

### Claim 1

A white polyester film which is formed with a polyester resin whose main constituent is ethylene terephthalate, and satisfies the following requirements (1) to (6):
(1) the film consists of either (a) two layers: a white layer and a heat sealing layer or (b) three layers: a heat sealing layer/a white layer/a heat sealing layer, wherein at least one of the film surfaces is the heat sealing layer, and the white layer comprises a thermoplastic resin immiscible with the polyester;
(2) the film has a peeling strength of 4 N/15 mm or more and 25 N/15 mm or less when the heat sealing layers of two identical polyester films are heat-sealed to each other at 160° C. and 0.2 MPa for 2 seconds;
(3) the heat sealing layer of the polyester film has a difference in reversing heat capacity of 0.18 J/g·K or more and 0.35 J/g·K or less, and wherein the difference in reversing heat capacity is measured between at a lower and a higher temperature than a glass transition temperature with a temperature modulated DSC;
(4) the film has a heat shrinkage of −10% or more and 10% or less both in a longitudinal direction and in a width direction when treated in hot water at 80° C. for 10 seconds;
(5) the film has a total light transmittance of 20% or more and 40% or less; and
(6) the film has an apparent specific gravity of 0.90 or more and 1.30 or less.

### Claim 2 (depends on 1)

The white polyester film according to claim 1, wherein a polyester component constituting the polyester film is formed from at least one selected from the group consisting of neopentyl glycol, 1,4-cyclohexanedimethanol, isophthalic acid, and diethylene glycol.

### Claim 3 (depends on 2)

The white polyester film according to claim 2, wherein the polyester component constituting the polyester film is formed from 1,4-butanediol.

### Claim 4 (depends on 3)

The white polyester film according to claim 3, wherein the film has a thickness of 5 to 200 μm.

### Claim 5 (depends on 1)

The white polyester film according to claim 1, wherein a polyester component constituting the polyester film is formed from 1,4-butanediol.

### Claim 6 (depends on 5)

The white polyester film according to claim 5, wherein the film has a thickness of 5 to 200 μm.

### Claim 7 (depends on 1)

The white polyester film according to claim 1, wherein the film has a thickness of 5 to 200 μm.

### Claim 8 (depends on 1)

A packaging bag including at least one of the white polyester film according to claim 1.

### Claim 9 (depends on 3)

A packaging bag including at least one of the white polyester film according to claim 3.

### Claim 10 (depends on 4)

A packaging bag including at least one of the white polyester film according to claim 4.

### Claim 11 (depends on 1)

A laminate comprising at least one layer of the white polyester film according to claim 1.

### Claim 12 (depends on 3)

A laminate comprising at least one layer of the white polyester film according to claim 3.

### Claim 13 (depends on 4)

A laminate comprising at least one layer of the white polyester film according to claim 4.

### Claim 14 (depends on 11)

A packaging bag including at least one of the laminate according to claim 11.

### Claim 15 (depends on 12)

A packaging bag including at least one of the laminate according to claim 12.

### Claim 16 (depends on 13)

A packaging bag including at least one of the laminate according to claim 13.

### Claim 17 (depends on 1)

The white polyester film according to claim 1, wherein the thermoplastic resin is formed from at least one resin selected from the group of a polystyrene-based resin, a polyolefin-based resin, a polyacrylic-based resin, a polycarbonate-based resin, a polysulfone-based resin, and a cellulose-based resin.