Abstract: A front end portion of a following film is superimposed on a rear end portion of a preceding film to form a superimposed portion, and is joined thereto by a double-sided adhesive tape. The length of the double-sided adhesive tape in a film conveyance direction is shorter than that of the superimposed portion. The double-sided adhesive tape adheres to the rear end portion with leaving a rear space from a rear edge, and to the front end portion with leaving a front space from a front edge. The length of the rear space in the film conveyance direction is a maximum shrinkage of a first area, being a part of the front end portion superimposed on the rear space, or more. Likewise, the length of the front space in the film conveyance direction is a maximum shrinkage of a second area or more.

Abstract: A front end portion of a following film is superimposed on a rear end portion of a preceding film to form a superimposed portion, and is joined thereto by a double-sided adhesive tape. The length of the double-sided adhesive tape in a film conveyance direction is shorter than that of the superimposed portion. The double-sided adhesive tape adheres to the rear end portion with leaving a rear space from a rear edge, and to the front end portion with leaving a front space from a front edge. The length of the rear space in the film conveyance direction is a maximum shrinkage of a first area, being a part of the front end portion superimposed on the rear space, or more. Likewise, the length of the front space in the film conveyance direction is a maximum shrinkage of a second area or more.

Abstract: A rear end of a preceding film and a front end of a trailing film are overlapped with an overlap length Lo. Each of a pair of welding heads has a contact surface and a film heating surface. The contact surface has a length Lp in a conveying direction. The film heating surface has a length Lh in the conveying direction. The lengths Lh, Lo, and Lp satisfy Lh<Lo<Lp. Center portions of an overlapped portion, the contact surface, and the heat surface are approximately aligned with each other in the conveying direction. The overlapped portion is sandwiched by the welding heads in an overlapping direction C. The overlapped portion is welded through the film heating surfaces such that temperatures of the films at both ends of each contact surface in the conveying direction are heated to a temperature at which the films are welded.

Abstract: A TAC film has a thickness profile in which its thickness decreases from side edge portions toward a center portion. The TAC film has a retardation profile in which its in-plane retardation Re decreases from the side edge portions toward the center portion. The retardation profile is caused by the thickness profile. In a tenter section, the TAC film is stretched in a width direction while the side edge portions are being held. A difference of increase in the in-plane retardation Re of the film in the width direction after the stretching is compensated by a difference of the in-plane retardation Re of the film in the width direction before the stretching.

Abstract: TAC and additives are mixed in a mixture solvent of dichloromethane, methanol and n-butanol to obtain a dispersion solution. The dispersion solution is heated to become a low concentration dope whose concentration is 19.3 wt. %. The low concentration dope is fed with a pump, and supplied through a flash nozzle to a concentrating apparatus to performing flash evaporation of the solvent in the concentrating apparatus. Thus part of the solvent in the low concentration dope evaporates to obtain a condensed dope. The part of the solvent is condensed on a condensation surface to obtain a condensed solvent. The condensed solvent flows through a pipe out of the concentrating apparatus. The high concentration dope has a solid content of 22.3 wt. %, and drawn through a pump. As the solid content of the high concentration dope is high, a polymer film having the self-supporting property can be easily formed of the high concentration dope in a film production line.

Abstract: An low concentration dope is fed through a nozzle into a concentrating apparatus, and flash evaporation of the low concentration dope is performed at an end of the nozzle. The low concentration dope is concentrated thereby to an concentrating dope which is contained and heated in the concentrating apparatus. Thus part of solvents of the low concentration dope and the concentrating dope is evaporated to a solvent gas. The solvent gas is cooled and condensed in a condensing section of the concentrating apparatus, and thereafter drawn through a first exit from the concentrating apparatus. The concentrating dope is concentrated to a high concentration dope, which is drawn through a second exit from the concentrating apparatus.

Abstract: An low concentration dope is fed through a nozzle into a concentrating apparatus, and flash evaporation of the low concentration dope is performed at an end of the nozzle. The low concentration dope is concentrated thereby to an concentrating dope which is contained and heated in the concentrating apparatus. Thus part of solvents of the low concentration dope and the concentrating dope is evaporated to a solvent gas. The solvent gas is cooled and condensed in a condensing section of the concentrating apparatus, and thereafter drawn through a first exit from the concentrating apparatus. The concentrating dope is concentrated to a high concentration dope, which is drawn through a second exit from the concentrating apparatus.

Abstract: An low concentration dope is fed through a nozzle into a concentrating apparatus, and flash evaporation of the low concentration dope is performed at an end of the nozzle. The low concentration dope is concentrated thereby to an concentrating dope which is contained and heated in the concentrating apparatus. Thus part of solvents of the low concentration dope and the concentrating dope is evaporated to a solvent gas. The solvent gas is cooled and condensed in a condensing section of the concentrating apparatus, and thereafter drawn through a first exit from the concentrating apparatus. The concentrating dope is concentrated to a high concentration dope, which is drawn through a second exit from the concentrating apparatus.

Abstract: A casting die casts onto a belt a dope containing TAC for producing a film after the drying. Edge determining devices having edge correction paths are attached to both sides of a main body of the casting die. Part of the dope is fed as edge correction dopes in edge correction paths, and the remaining part of the dope is fed as a main dope in the manifold. A thickness of the main dopes is regulated so as to control the thickness of the film. In a casting film formed from the dope, both edge portions are thicker than a middle portion, and therefore the strength of the edge portions and the casting film increases. Thus when the casting film is peeled from the belt, the peeling defects are reduced. The edge portions are slit of to obtain a thin film.

Abstract: TAC and additives are mixed in a mixture solvent of dichloromethane, methanol and n-butanol to obtain a dispersion solution. The dispersion solution is heated to become a low concentration dope whose concentration is 19.3 wt. %. The low concentration dope is fed with a pump, and supplied through a flash nozzle to a concentrating apparatus to performing flash evaporation of the solvent in the concentrating apparatus. Thus part of the solvent in the low concentration dope evaporates to obtain a condensed dope. The part of the solvent is condensed on a condensation surface to obtain a condensed solvent. The condensed solvent flows through a pipe out of the concentrating apparatus. The high concentration dope has a solid content of 22.3 wt. %, and drawn through a pump. As the solid content of the high concentration dope is high, a polymer film having the self-supporting property can be easily formed of the high concentration dope in a film production line.

Abstract: An low concentration dope is fed through a nozzle into a concentrating apparatus, and flash evaporation of the low concentration dope is performed at an end of the nozzle. The low concentration dope is concentrated thereby to an concentrating dope which is contained and heated in the concentrating apparatus. Thus part of solvents of the low concentration dope and the concentrating dope is evaporated to a solvent gas. The solvent gas is cooled and condensed in a condensing section of the concentrating apparatus, and thereafter drawn through a first exit from the concentrating apparatus. The concentrating dope is concentrated to a high concentration dope, which is drawn through a second exit from the concentrating apparatus.

Abstract: A solution applying method in which a continuously conveyed web is applied with a coating solution by a solution injector. The solution injector includes a lip with a lower end portion thereof having an angle of 85.degree. or less relative to a surface of the injector. A coating solution flows along the lip of the solution injector to form a bead between the lip and the web. The solution applying conditions and pressures before and after the bead is formed between the web and the lip are controlled before the coating solution is applied to the web such that a lower end portion of the bead coincides with the lower end portion of the lip. The solution applying device may have a lower end portion of the lip with an angle of not more than 89.degree.. A portion of the lip may extend parallel to a roller conveying the web and has a length of 0.1-10 mm.

Abstract: A plastic bag forming and sealing apparatus including a container for a roll of plastic to be formed into bags, the side margins of the roll are presealed to form the plastic into a tube; the roll is unwound to the desired extent, the cover of the container is closed to hold the unwound plastic in place, a blade is moved across the roll to shear the desired length of a plastic bag, with the cover still closed, heat seal means seals the open end of the tube completing the formation of an open sided bag or pouch to be filled.