Multi-component composite film method for preparing the same

A preparation method of a multi-component composite film, comprising:

• a porous polymeric support layer film;
• and
• a porous gellable polymer layer which is formed on one side or both sides of the polymeric support layer film, wherein a pore size of the porous polymeric support layer film is different than a pore size of the porous gellable polymer layer and wherein the porous polymeric support layer film and the porous gellable polymer layer are joined directly to each other, which comprises:
• preparing a nonporous polymeric support layer film;
• dissolving a gellable polymer in a solvent in order to prepare a gellable polymer solution;
• forming a porous gellable polymer layer on one side or both sides of the nonporous polymeric support layer film by coating a release film with the gellable polymer solution to form a gellable polymer layer on it, drying the coated film to form a porous gellable polymer layer, desorbing the porous gellable polymer layer from the release film, and heat-setting the desorbed porous gellable polymer layer film on one side or both sides of the nonporous polymeric support layer film in order to prepare a multiple layer;
• and
• stretching and heat-setting the multiple layer to prepare a multi-component composite film comprising the porous polymeric support layer film and the porous gellable polymer layer wherein the pore size of the porous polymeric support layer film is different than the pore size of the porous gellable polymer layer and wherein the porous polymeric support layer film and the porous gellable polymer layer are joined directly to each other,
• wherein pores are formed on the polymeric support layer film by the stretching step, and
• wherein pores are formed on the gellable polymer layer by a phase transition process including the coating and drying steps, and by the stretching step,
• wherein a material of the polymeric support layer film is at least one selected from the group consisting of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, high crystalline polypropylene, polyethylene-propylene copolymer, polyethylene-butylene copolymer, polyethylene-hexene copolymer, polyethylene-octene copolymer, polystyrene-butylene-styrene copolymer, polystyrene-ethylene-butylene-styrene copolymer, polystyrene, polyphenylene oxide, polysulfone, polycarbonate, polyester, polyamide, polyurethane, polyacrylate, polyvinylidene chloride, polyvinylidene fluoride, polysiloxane, polyolefin ionomer, polymethyl pentene, hydrogenated oligocyclopentadiene (HOCP), and a mixture thereof or a derivative thereof,
• the gellable polymer is at least one selected from the group consisting of polyvinylidene fluoride, polyvinylidene fluoride-chlorotrifluoroethylene copolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polypropylene oxide, polybutylene oxide, polyurethane, polyacrylonitrile, polyacrylate, polymethyl methacrylate, polyacrylic acid, polyamide, polyacrylamide, polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polysulfone, polyphenylene oxide, polycarbonate, polyester, polyvinylidene chloride, polysiloxane, polyolefin ionomer, and a copolymer thereof or a derivative thereof,
• the gellable polymer solution is prepared by adding at least one lithium salt selected from the group consisting of LiSCN, LiClO4, LiCF3SO3, LiAsF6, LiN(CF3SO2), and LiBF4 to the solvent, and by adding at least one porous inorganic particle selected from the group consisting of SiO2, TiO2, Al2O3, MgO, and B2O3 to the solvent,
• the thickness of the porous polymeric support layer film ranges from 1 to 50 μm, and the thickness of the porous gellable polymer layer ranges from 0.01 to 25 μm,
• an interfacial adhesive strength measured by the method according to JIS Z 0237 between the porous polymeric support layer film and the porous gellable polymer layer is from 150 to 250 gf, and
• the air permeability of the multi-component composite film is from 100 to 20,000 sec/100 cc.