The present invention relates to a method for manufacturing a polyimide-based film and a polyimide-based film manufactured thereby and, particularly, to a method for manufacturing a polyimide-based film and a polyimide-based film manufactured thereby, wherein the polyimide-based film is useful as a cover substrate for a flexible electronic device since flexure characteristics thereof, represented by yield elongation, are excellent.

A technology for improving molding properties while minimizing curling after molding in a battery packaging material comprising a laminate that is provided with a barrier layer, a heat-sealable resin layer positioned on one surface side of the barrier layer, and a polyester film positioned on the other surface side of the barrier layer. This battery packaging material is configured from at least a laminate provided with a barrier layer, a heat-sealable resin layer positioned on one surface side of the barrier layer, and a polyester film positioned on the other surface side of the barrier layer. The birefringence of the polyester film is in the range of 0.016-0.056.

A technology for improving molding properties while minimizing curling after molding in a battery packaging material comprising a laminate that is provided with a barrier layer, a heat-sealable resin layer positioned on one surface side of the barrier layer, and a polyester film positioned on the other surface side of the barrier layer. This battery packaging material is configured from at least a laminate provided with a barrier layer, a heat-sealable resin layer positioned on one surface side of the barrier layer, and a polyester film positioned on the other surface side of the barrier layer. The birefringence of the polyester film is in the range of 0.016-0.056.

A resin molding system 1 comprises a gripping device 3 provided with a gripping frame 30 for gripping a resin sheet material 2, a heating device for heating the resin sheet material 2 and a molding device for clamping a lower die 61 and an upper die, and affixing the resin sheet material 2 to a substrate 63. The molding device is provided with: a lowering device for lowering the gripping device 3 and causing the resin sheet material 2 gripped by the gripping frame 30 to approach the lower die 61; and a pair of bent posts 67, 68 which are provided on both Y-direction sides of the lower die 61, and which come in contact with portions of the gripping frame 30 when the gripping device 3 is lowered, and which convexly bend the gripping frame 30 upward as viewed from the side along the Y-direction.

In some embodiments, the present invention is directed to an actuator which includes at least the following: a pre-stretched electro-active polymer film being pre-stretched in a single or biaxial planar directions; at least one first semi-stiff conductor attached to a first surface of the pre-stretched electro-active polymer film, wherein the first surface is parallel to the single or biaxial planar stretch directions; at least one second semi-stiff conductor attached to a second surface of the pre-stretched electro-active polymer film, wherein the second surface is opposite to the first surface; where the semi-stiff conductors are configured to: fix the pre-stretched electro-active polymer film in a pre-stretched state and allow the pre-stretched electro-active polymer film to expand; a pair of mechanical connectors coupled to each end of an active region of the pre-stretched electro-active polymer film.

[Problem] To provide: a biaxially oriented polyester film that exhibits excellent transparency, enables easy secondary processing such as coating and vapor deposition, provides excellent post-secondary-processing properties, and is environmentally friendly in that the film is made from polyester resins recycled from the market and society, including those from PET bottles; and a production method for such a film. [Solution] A biaxially oriented polyester film comprising a polyester resin composition containing particles and polyester resins recycled from the market and society, including those from PET bottles, the film having at least one surface that satisfies all requirements (1)-(3). (1) The number of fine projections having a height less than 3 nm per an area of 4×10-12m2 is 250-600. (2) The number of fine projections having a height not less than 3 nm per an area of 4×10-12m2 is 300-600. (3) The arithmetic average height Sa is 0.01-0.025 μm.

Provided is a porous polytetrafluoroethylene membrane in which an absolute value of a difference in lightness between one principal surface and the other principal surface is 1.0 or more, where the lightness is lightness L* of CIE 1976 (L*, a*, b*) color space specified in JIS Z8781-4: 2013. The porous polytetrafluoroethylene membrane may be colored black or gray. The porous polytetrafluoroethylene membrane provided can have properties with a reduced coloring-induced deterioration.

A method is for producing a coextruded and biaxially stretched composite film using a novel combination of stretching and relaxation steps. A corresponding composite film has little or no shrinkage.

Provided is a biaxially oriented polypropylene film that has high stiffness, has excellent heat resistance at a high temperature of 150° C., easily maintains a bag shape when being made into a packaging bag, and has less pitch shift during printing or fewer wrinkles in a sealed portion when being heat-sealed. A biaxially oriented polypropylene film, wherein a stress at 5% elongation (F5) at 23° C. of the biaxially oriented polypropylene film is not lower than 40 MPa in a longitudinal direction and not lower than 160 MPa in a width direction, and a heat shrinkage rate at 150° C. of the biaxially oriented polypropylene film is not higher than 7% in the longitudinal direction and not higher than 16% in the width direction.

In the polyester film according to an embodiment, the strain with respect to tensile load and the crystallinity are adjusted to specific ranges, whereby it is possible to achieve the flexibility that does not cause deformation even when a certain load is sustained for a long period of time and the resistant characteristics to the impact of external pressing. Accordingly, the polyester film can be applied to a cover of a flexible display device, in particular, a foldable display device to exhibit excellent characteristics.