TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Compound: The denatured clay is natural clay or synthetic clay, preferably mica, vermiculite, montmorillonite, beidellite, saponite, hectorite, stevensite, magadiite, ilerite, kanemite, illite and/or sericite. The non-denatured clay is natural or synthetic clay, preferably mica, vermiculite, montmorillonite, iron montmorillonite, beidellite, saponite, hectorite, stevensite or nontronite. Preferred Composition: The denatured clay comprises quaternary ammonium cations or quaternary phosphonium cations as organic cations. The multilayer film comprises a film containing non-denatured clay. Preferred Properties: The content of the organic cation composition in denatured clay is 30 wt.% or less. The chlorine concentration in the film is 150 ppm or less. The content of silylating agent with respect to total content of clay and silylating agent is 30 wt.% or less. The exchangeable ions (50%) in the denatured clay are lithium ions. The film in the multilayer film has weight ratio of non-denatured clay of 70% with respect to clay total solids. Preferred Process: The denatured clay is obtained by reacting clay with a silylating agent.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The pre-gel solvent is water. The polar solvent is ethanol or dimethylacetamide.    TECHNOLOGY FOCUS - POLYMERS - Preferred Compound: The additive is celluloid, phenolic resin, alkyd resin, urea resin, cellulose acetate, vinyl acetate resin, acrylic resin, styrene resin, vinyl chloride resin, melamine resin, polyethylene, polyurethane resin, vinylidene chloride resin, polyamide resin, unsaturated polyester, silicon resin, acrylonitrile-styrene resin, fluororesin, epoxy resin, diallyl phthalate resin, acrylonitrile-butadiene-styrene resin, polyethylene terephthalate, polypropylene, polycarbonate, polyacetal, polyimide, polysulfone, polyphenylene ether, polybutylene terephthalate, polyethersulfone, liquid crystal polymer, polyphenylene sulfide and/or polyetherimide. The epoxy resin is lignin-based epoxy resin or sucrose-based epoxy resin. The ends of silylated clay (A) are epoxy groups. The ends of silylated clay (B') are amino groups. The additive of film containing non-denatured clay is epsilon caprolactam, dextrin, starch, cellulose resin, gelatin, agar, wheat flour, gluten, alkyd resin, polyurethane resin, epoxy resin, fluororesin, acrylic resin, methacrylic resin, phenolic resin, polyamide resin, polyester resin, polyimide resin, polyvinyl resin, polyethylene glycol, polyacrylamide, polyethylene oxide, protein, deoxyribonucleic acid, ribonucleic acid, polyamino acid, polyhydric phenol or benzoic acid compound. Preferred Process: The water resistance of the film is enhanced by thermal treatment. The silylated clay is epoxy-terminated silylated clay, and covalent bonds are formed between clays by epoxy reaction during film manufacture. The silylated clay (A) and silylated clay (B') are mixed, and covalent bonds are formed between clays by reacting ends of the silylated clay (A) with ends of silylated clay (B'). The film is subjected to surface treatment, preferably water-repellency treatment, water-proofing treatment, reinforcement treatment or surface flattening treatment. The surface treatment is carried out by forming a silicon oxide film, a fluorine-based film, a silicon-based film, a polysiloxane film, a fluorine-containing organopolysiloxane film, an acrylic resin film, a vinyl chloride resin film, a polyurethane resin film, a high water-repellent plating film, a metallic vapor deposition film or a carbon vapor deposition film on the surface of the film. The film is reinforced with a reinforcing material. The light transmittance, gas barrier property, water-vapor barrier property or mechanical strength of the film are improved by forming new chemical bonds within molecules of additive, between additive and an inorganic layered compound, and between inorganic layered compound crystals through chemical reaction such as addition reaction, condensation reaction or polymerization reaction by heating or light irradiation. Preferred Composition: The reinforcing material comprises mineral fiber, glass wool, carbon fiber, ceramic fiber, plant fiber or organic polymer fiber. The reinforcing material is in the form of fabric, preferably woven fabric, nonwoven fabric or paper. The plastic film contains polyethylene, polypropylene, polyethylene terephthalate, polyamide, fluororesin, acrylic resin, polyimide, polyallylate, polysulfone and/or polyetherimide. Preferred Component: The surface protection film protects a to-be-protected component of metal, metal oxide, ceramic, plastic, plastic foamed material, wood, plaster and rubber. Preferred Properties: The weight ratio of reinforcing material is 30%. The film has thickness of 0.003-0.3 mm, permeability coefficient at room temperature with respect to oxygen gas of 2x 10-9 or less cm2second-1cmHg-1, water-vapor permeability at 40 degrees C and relative humidity of 90% of 10 gm-2day-1 or less, water absorption rate at 20 degrees C and relative humidity of 65% of 2% or less, bending radius of 8 mm without cracking, 5%-weight reduction temperature of 235-760 degrees C measured by thermogravimetry, average linear thermal expansion coefficient of film at 50-250 degrees C along a direction parallel to the film plane of 5-10 ppm, volume resistivity along direction perpendicular to the film of 2.8x 1011 Omega .cm, ion conductivity along direction perpendicular to the film of 1x 10-4 Scm-1, exhibits no visibly observable damage in shape, and has permeability coefficient with respect to oxygen gas at room temperature of 2x 10-9cm2second-1cmHg-1, after immersion in superheated water at 150 degrees C for 1 hour. The weight ratio of additive in the multilayer film is 30%. The thickness of film in the multilayer film is 0.003-0.5 mm. The multilayer film has permeability coefficient with respect to oxygen gas at room temperature of 2x 10-9 cm2second-1cmHg-1 or less, water-vapor permeability at 40 degrees C and relative humidity of 90% of 6 gm-2day-1 or less.