# US 12,112,957 B2 · Release film and method of manufacturing release film

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- Number: US 12,112,957 B2
- Document ID: US12112957B2
- Status: Granted
- Kind: B2
- Application number: 17/252,136
- Filed: 2019-04-08
- Published: 2021-08-19
- Granted: 2024-10-08
- Earliest claimed: 2018-06-22
- Assignees: Kobayashi & Co., Ltd.
- Applicants: Kobayashi & Co., Ltd.
- Inventors: Keisuke Sakai; Norifumi Iwawaki; Nanae Tanaka; Satoshi Hiramatsu; Akane Kawafuchi
- Web page: https://patentgrep.com/patent/US12112957B2

## CPC

- H10W 74/017: {Auxiliary layers for moulds, e.g. release layers or layers preventing residue}
- B29C 33/68: Release sheets
- B32B 27/00: Layered products comprising {a layer of} synthetic resin {(fibrous or filamentary layer made of a synthetic resin B32B5/02; particulate layer made of a synthetic resin B32B5/16; foamed layer made of a synthetic resin B32B5/18)}
- B32B 27/30: comprising vinyl {(co)polymers; comprising acrylic (co)polymers}
- B32B 27/36: comprising polyesters
- H10W 74/47: comprising organic materials, e.g. plastics or resins
- H10W 72/0198: {batch processes}
- H10W 74/00: Encapsulations, e.g. protective coatings
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- 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

## Abstract

To provide a release film not to contaminate a mold or a molded article. The present invention provides a release film comprising a base layer formed of an easily moldable polyethylene terephthalate resin and surface layers laminated on two faces of the base layer and formed of a fluororesin. The present invention also provides a method of manufacturing a release film. The method comprises an applying step of applying a fluororesin composition onto two faces of a base layer formed of an easily moldable polyethylene terephthalate resin and, after the applying step, a curing step of curing the fluororesin composition. By molding with the release film, contamination of a mold or a molded article is prevented. The release film can be used in molding multiple times.

## Claims

### Claim 1

A release film comprising:
a base layer formed of an easily moldable polyethylene terephthalate resin; and
surface layers laminated on two faces of the base layer and formed of a fluororesin;
wherein the easily moldable polyethylene terephthalate resin has a glass transition temperature of 60° C. to 95° C.,
the fluororesin that forms the surface layer comprises a tetrafluoroethylene resin, and the fluororesin that forms the surface layer on at least one face of the base layer comprises particles having an average particle size of 1 μm to 10 μm determined by laser diffraction particle size analysis, and contains a combination of isocyanate-type polyisocyanate and an adduct-type polyisocyanate.

### Claim 2 (depends on 1)

The release film according to claim 1, wherein the content of a tetrafluoroethylene resin in the fluororesin is 70% by mass or more relative to the total mass of the fluororesin.

### Claim 3 (depends on 1)

The release film according to claim 1, wherein
the release film has a tensile breaking strength of 40 MPa to 200 MPa as determined at 175° C. in accordance with JIS K7127, and
the release film has a tensile elongation at break of 200% to 500% as determined at 175° C. in accordance with JIS K7127.

### Claim 4 (depends on 1)

The release film according to claim 1, wherein the release film has an oxygen gas permeability of 5,000 to 50,000 cc/m2·24 hr·atm as determined at 175° C. in accordance with JIS K7126-1.

### Claim 5 (depends on 1)

The release film according to claim 1, wherein the base layer has a tensile breaking strength of 40 MPa to 200 MPa as determined at 175° C. in accordance with JIS K7127.

### Claim 6 (depends on 1)

The release film according to claim 1, wherein the base layer has a tensile elongation at break of 200% to 500% as determined at 175° C. in accordance with JIS K7127.

### Claim 7 (depends on 1)

The release film according to claim 1, wherein the fluororesin that forms the surface layer on at least one face of the base layer comprises an isocyanate curing agent.

### Claim 8 (depends on 1)

The release film according to claim 1, wherein the particles are inorganic particles or organic particles.

### Claim 9 (depends on 1)

The release film according to claim 1, wherein the thickness of the surface layer is 1 μm to 10 μm.

### Claim 10 (depends on 1)

The release film according to claim 1, used for transfer molding or compression molding.

### Claim 11 (depends on 1)

The release film according to claim 1, used for molding two or more times.