Release film and method for manufacturing release film
To provide a release film having an electrostatic dissipative property. The present invention provides a release film comprising a base layer formed of a polyester resin and a surface layer formed of a tetrafluoroethylene resin that comprises an electrically conductive filler, and the release film has a surface resistivity Rs of 1×10 11 Ω or less. Preferably, the electrically conductive filler comprises carbon black, and the tetrafluoroethylene resin further comprises particles having an average particle size of 1 μm to 15 μm determined by laser diffraction particle size analysis.
1 . A release film, comprising:
a base layer comprised of a polyester resin; and
a surface layer comprised of a tetrafluoroethylene resin comprising an electrically conductive filler,
wherein:
the release film has a surface resistivity (Rs) of 1×10 11 Ω or less,
the electrically conductive filler comprises carbon black,
the tetrafluoroethylene resin is a cured product which comprises a reactive functional group-containing tetrafluoroethylene polymer and a curing agent,
the reactive functional group-containing tetrafluoroethylene polymer comprises a polymer unit based on a hydroxy group-containing monomer and a polymer unit based on perfluoroolefin comprising tetrafluoroethylene and one or more of hexafluoropropylene and perfluoro (alkyl vinyl ethers),
the tetrafluoroethylene resin comprises silicon dioxide particles each having an average particle size of 1 μm to 15 μm, as determined by laser diffraction particle size analysis, and
an amount of the silicon dioxide particles relative to 100 parts by mass of the tetrafluoroethylene resin is 5.15 parts by mass to 15.79 parts by mass.
2 . The release film according to claim 1 , wherein the carbon black comprises ketjen black.
3 . The release film according to claim 2 , wherein the ketjen black has a dibutyl phthalate (DBP) oil absorption amount of 250 ml/100 g or more.
4 . The release film according to claim 1 , wherein the carbon black further comprises furnace black, and wherein a DBP oil absorption amount of the furnace black is 200 ml/100 g or less.
5 . The release film according to claim 1 , wherein the carbon black further comprises a ketjen black, and wherein the ketjen black has an average particle size of 1 μm to 20 μm, as determined by laser diffraction particle size analysis.
6 . The release film according to claim 1 , wherein the carbon black further comprises a furnace black, and wherein the furnace black has an average particle size of 30 nm to 150 nm, as determined by electron microscopy particle size analysis.
7 . The release film according to claim 1 , wherein the curing agent is an isocyanate curing agent.
8 . The release film according to claim 7 , wherein the isocyanate curing agent is: (i) a single polyisocyanate, or (ii) hexamethylene diisocyanate (HDI) polyisocyanate and one or more polyisocyanates selected from isocyanurate-containing polyisocyanates, adduct-containing polyisocyanates, and biuret-containing polyisocyanates.
9 . The release film according to claim 1 , wherein an amount of the electrically conductive filler contained in the tetrafluoroethylene resin composition is 1 part by mass to 25 parts by mass relative to 100 parts by mass of the reactive functional group-containing tetrafluoroethylene polymer.
10 . The release film according to claim 1 , wherein the polyester resin is a polyethylene terephthalate resin.
11 . The release film according to claim 1 , wherein the polyester resin has a glass transition temperature of 60° C. to 95° C.
12 . The release film according to claim 1 , wherein the surface layer is laminated on one face of two faces of the base layer.
13 . The release film according to claim 12 , wherein on another face of the two faces of the base layer, a surface layer comprised of a fluororesin is laminated.
14 . The release film according to claim 1 , wherein, when sealing a semiconductor with the release film, the release film is placed so that the surface layer that is comprised of the tetrafluoroethylene resin comprising the electrically conductive filler comes into contact with a sealing resin.
15 . A method for manufacturing a release film, the method comprising:
a surface layer forming step of forming, on one face of two faces of a base layer that is comprised of a polyester resin, a surface layer comprised of a tetrafluoroethylene resin comprising an electrically conductive filler, wherein:
the electrically conductive filler comprises carbon black,
the tetrafluoroethylene resin is a cured product of a tetrafluoroethylene resin composition containing a reactive functional group-containing tetrafluoroethylene polymer and a curing agent,
the reactive functional group-containing tetrafluoroethylene polymer contains a polymer unit based on a hydroxy group-containing monomer and a polymer unit based on perfluoroolefin comprising at least tetrafluoroethylene and one or more of hexafluoropropylene and perfluoro (alkyl vinyl ethers),
the tetrafluoroethylene resin comprises silicon dioxide particles,
an average particle size of the silicon dioxide particles is 1 μm to 15 μm, as determined by laser diffraction particle size analysis,
an amount of the silicon dioxide particles relative to 100 parts by mass of the tetrafluoroethylene resin is 5.15 parts by mass to 15.79 parts by mass, and
the manufactured release film has a surface resistivity Rs of 1×10 11 Ω or less.
16 . The method according to claim 15 , wherein in the surface layer forming step, the tetrafluoroethylene resin composition applied to the surface of the base layer is cured to form the cured product.