Release film and method of manufacturing release film
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.
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.
2. 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.
3. 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.
4. The release film according to claim 1 , wherein the release film has an oxygen gas permeability of 5,000 to 50,000 cc/m 2 ·24 hr·atm as determined at 175° C. in accordance with JIS K7126-1.
5. 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.
6. 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.
7. 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.
8. The release film according to claim 1 , wherein the particles are inorganic particles or organic particles.
9. The release film according to claim 1 , wherein the thickness of the surface layer is 1 μm to 10 μm.
10. The release film according to claim 1 , used for transfer molding or compression molding.
11. The release film according to claim 1 , used for molding two or more times.