TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Film: In the film (F1), exchangeable ions of the denatured clay (at least 50%) are lithium ions, where the water resistance of the film (F1) is enhanced through a thermal treatment. The light transmittance, gas barrier properties, water-vapor barrier properties or mechanical strength are improved by forming new chemical bonds within molecules of the additive, between the molecules of the additive, between the additive and an inorganic layered compound, and between inorganic layered compound crystals, through a chemical reaction such as an addition reaction, a condensation reaction or a polymerization reaction, using method such as heating or light irradiation. Preferred Components: The denatured/non-denatured clay is made of natural clay or synthetic clay. The clay used in the denatured clay is at least one of mica, vermiculite, montmorillonite, beidellite, saponite, hectorite, stevensite, magadiite, ilerite, kanemite, illite and sericite. The denatured clay comprises quaternary ammonium cations or quaternary phosphonium cations, as organic cations, where an organic cation composition in the denatured clay is less than 30 wt.%, and chlorine concentration is less than 150 parts per million (ppm). The denatured clay is obtained by reacting clay with silylating agent, where the composition of silylating agent relative to the clay and silylating agent is less than 30 wt.%. The silylated clay is epoxy-terminated silylated clay, and covalent bonds are formed between clays by an epoxy reaction in a film manufacture process. A silylated clay A and a silylated clay B are mixed, and covalent bonds are formed between clays by causing the ends of the silylated clay A to react with the ends of the silylated clay B, where the ends of the silylated clay A are epoxy groups, and the ends of the silylated clay B are amino groups. The non-denatured clay is at least one of mica, vermiculite, montmorillonite, iron montmorillonite, beidellite, saponite, hectorite, stevensite and nontronite.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The pre-gel solvent of denatured clay is water. The polar solvent is ethanol or dimethylacetamide.    TECHNOLOGY FOCUS - POLYMERS - Preferred Film: The film (F1) is subjected to a surface treatment (preferably water-repellency treatment, water-proofing treatment, reinforcement treatment, or surface flattening treatment). The surface treatment comprises forming, on the surface of the film (F1), silicon oxide film, fluorine-based film, silicon-based film, polysiloxane film, fluorine-containing organopolysiloxane film, an acrylic resin film, a vinyl chloride resin film, polyurethane resin film, high water-repellent plating film, metallic vapor deposition film, or carbon vapor deposition film. The thickness of the film (F1) is 0.003-0.3 mm. The film (F1) is reinforced with a reinforcing material. The multilayer film (F2) comprises film having non-denatured clay, where the weight ratio of the non-denatured clay is at least 70% relative to clay total solids. The thickness of the film (F2) is 0.003-0.5 mm. The composite multilayer film (F3) comprises plastic film, at least one of polyethylene, polypropylene, polyethylene terephthalate, polyamide, fluororesin, acrylic resin, polyimide, polyallylate, polysulfone and polyetherimide. Preferred Components: The additive in the film (F1) is at least one of 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, silicone 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 polyetherimide, where the epoxy resin is a lignin-based epoxy resin or sucrose-based epoxy resin. The reinforcing material is selected from mineral fibers, glass wool, carbon fibers, ceramic fibers, plant fibers and organic polymer fibers. The reinforcing material has the form of a fabric (preferably woven fabric, nonwoven fabric or paper). The weight ratio of the reinforcing material in the film (F1) is at most 30% relative to total solids. The additive of the film (F2) having a non-denatured clay as a main component is at least one of 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 and benzoic acid compound. The weight ratio of the additive, in the film (F2) is at most 30% relative to total solids. EXAMPLE - A commercially available product, in which dimethylstearylbenzyl-type quaternary ammonium ions, and trimethoxysilane as a silylating agent, were introduced in natural bentonite, was used as denatured clay. The denatured clay was added (14 g) to toluene (440 cm3), then placed in a plastic sealed container, followed by vigorous shaking for 2 hours at 25 degrees C to give homogeneous dispersion. The dispersion was divided into two, and then to each half were added, respectively, an epoxy resin (agent A) of commercially available epoxy-based adhesive agent (3 g), and denatured polyamide (agent B), followed by vigorous shaking to yield homogeneous dispersions. The two dispersions were mixed, followed by further vigorous shaking for 20 minutes at 25 degrees C to give a homogeneous clay paste. The clay paste was deaerated in a vacuum defoaming apparatus and then applied onto a metal plate having bonded to a 0.1 mm thick film to form molded clay paste film having a uniform thickness. The tray was left to dry naturally at room temperature, to give uniform denatured clay thin film having a thickness of 60 mu m. After standing for 24 hours, the denatured clay film was detached from the tray, to give a self-supporting film (WR30-60) (test) having excellent flexibility. Kunipia P (RTM: natural montmorillonite) (2.7 g), and Somasif ME-100 (RTM: synthetic mica) (0.72 g) were added, as clays, to distilled water (100 cm3), then placed in a plastic sealed container, followed by vigorous shaking for 2 hours at 25 degrees C to give homogeneous dispersion. To the dispersion was added, as an additive, methyl vinyl ether/maleic anhydride copolymer (0.18 g), followed by vigorous shaking, to yield a homogeneous dispersion comprising natural montmorillonite and methyl vinyl ether/maleic anhydride copolymer. The dispersion was dried gradually to give a clay paste. The clay paste was deaerated and then applied onto a brass plate to form clay paste film having a uniform thickness. The thickness of the paste was 2 mm. The tray was placed in a forced draft oven and was dried for 1 hour under temperature conditions of 60 degrees C, to give a homogeneous additive-composite clay film having a thickness of 40 mu m. The formed clay film was detached from the tray, to give a self-supporting clay film (HR) (comparative) having excellent flexibility. The test/comparative film was tested for water-vapor permeability at 40 degrees C and 90% relative humidity, and it was found to be 2.15/71.9 g/m2/day, respectively.