A release layer of a release film for producing a membrane electrode assembly of a polymer electrolyte fuel cell comprises a cyclic olefin polymer comprising an olefin unit having a C.sub.3-10alkyl group as a side chain thereof. The release layer may have a glass transition temperature of about 210 to 350 C. The release layer may have a transition point of a dynamic storage modulus E in a range from 50 to 100 C. An ion exchange layer comprising an ion exchange polymer may be laminated on the release layer of the release film by a roll-to-roll processing to produce a laminate. The release film may be separated from the laminate to give the membrane electrode assembly. The release film achieves improved production of a membrane electrode assembly (an electrolyte membrane and/or an electrode membrane) of a polymer electrolyte fuel cell.

A heat resistant release sheet of the present disclosure includes a polyimide substrate, and a first polytetrafluoroethylene (PTFE) layer and a second PTFE layer that sandwich the polyimide substrate therebetween. PTFE composing the first PTFE layer and PTFE composing the second PTFE layer each have a number-average molecular weight of 6 million or more, and a peel force required to peel the first PTFE layer from the polyimide substrate is 0.5 N/20 mm or more, and a peel force required to peel the second PTFE layer from the polyimide substrate is less than 0.5 N/20 mm. The heat resistant release sheet of the present disclosure has a new structure and can also be used for thermocompression bonding at a higher temperature.

A heat resistant release sheet of the present disclosure includes a polyimide substrate, and a first polytetrafluoroethylene (PTFE) layer and a second PTFE layer that sandwich the polyimide substrate therebetween. PTFE composing the first PTFE layer and PTFE composing the second PTFE layer each have a number-average molecular weight of 6 million or more, and a peel force required to peel the first PTFE layer from the polyimide substrate is 0.5 N/20 mm or more, and a peel force required to peel the second PTFE layer from the polyimide substrate is less than 0.5 N/20 mm. The heat resistant release sheet of the present disclosure has a new structure and can also be used for thermocompression bonding at a higher temperature.

A method for producing a fiber-reinforced composite material is provided. By satisfying particular conditions, this method is capable of suppressing the problem of poor appearance caused by the release film in the production of the fiber-reinforced composite material having a three-dimensional shape by heat-press molding to enable production of the fiber-reinforced composite material having a high quality appearance in high cycle. A method for manufacturing a fiber-reinforced composite material wherein a fiber-reinforced substrate containing a reinforcing fiber (A) and a thermosetting resin (B) is sandwiched between release films (C) to constitute a layered material, and the layered material is pressed in a mold heated to molding temperature to thereby cure the thermosetting resin (B), wherein the method satisfies the following (i), (ii), and (iii) or (i), (ii), and (iv): (i) the fiber-reinforced composite material has at least 1 bent part, (ii) the molding temperature is 130 to 180 C., and pressure application time is 0.5 to 20 minutes, (iii) the release film (C) has a thermal contraction rate satisfying the following expressions (1) and (2):
0<Ta20expression (1), and
1TaTb20expression (2), Ta: the thermal contraction rate (%) of the release film (C) measured by using a thermomechanical analyzer at the temperature the same as the molding temperature Tb: the thermal contraction rate (%) of the release film (C) measured by using a thermomechanical analyzer at a temperature 30 C. lower than the molding temperature, and (iv) hardness of the fiber-reinforced substrate and the hardness of the release film (C) measured by using a durometer corresponding to JIS-K-7215, type A satisfy the following expressions (3) and (4):
0.8Hrc/Hrf1.2expression (3),
1<Hhc/Hhf1.5expression (4), Hrc: hardness of the release film (C) at 30 C., Hrf: hardness of the fiber-reinforced substrate at 30 C., Hhc: hardness of the release film (C) at the molding temperature, Hhf: hardness of the fiber-reinforced substrate at the molding temperature.

A method for producing a fiber-reinforced composite material is provided. By satisfying particular conditions, this method is capable of suppressing the problem of poor appearance caused by the release film in the production of the fiber-reinforced composite material having a three-dimensional shape by heat-press molding to enable production of the fiber-reinforced composite material having a high quality appearance in high cycle. A method for manufacturing a fiber-reinforced composite material wherein a fiber-reinforced substrate containing a reinforcing fiber (A) and a thermosetting resin (B) is sandwiched between release films (C) to constitute a layered material, and the layered material is pressed in a mold heated to molding temperature to thereby cure the thermosetting resin (B), wherein the method satisfies the following (i), (ii), and (iii) or (i), (ii), and (iv): (i) the fiber-reinforced composite material has at least 1 bent part, (ii) the molding temperature is 130 to 180 C., and pressure application time is 0.5 to 20 minutes, (iii) the release film (C) has a thermal contraction rate satisfying the following expressions (1) and (2):
0<Ta20expression (1), and
1TaTb20expression (2), Ta: the thermal contraction rate (%) of the release film (C) measured by using a thermomechanical analyzer at the temperature the same as the molding temperature Tb: the thermal contraction rate (%) of the release film (C) measured by using a thermomechanical analyzer at a temperature 30 C. lower than the molding temperature, and (iv) hardness of the fiber-reinforced substrate and the hardness of the release film (C) measured by using a durometer corresponding to JIS-K-7215, type A satisfy the following expressions (3) and (4):
0.8Hrc/Hrf1.2expression (3),
1<Hhc/Hhf1.5expression (4), Hrc: hardness of the release film (C) at 30 C., Hrf: hardness of the fiber-reinforced substrate at 30 C., Hhc: hardness of the release film (C) at the molding temperature, Hhf: hardness of the fiber-reinforced substrate at the molding temperature.

A method for producing a composite material structure contains a film attachment step (S2) of attaching a protective film to a molding member; a molding step (S3) of attaching a composite material which is a heating target to the molding member from above the protective film, accommodating the molding member in a pressure container, and molding a molded article; and a molded article removal step (S4) of removing the molded article from the molding member to which the protective film is attached. The protective film is a heat-resistance mold release film having a fluorine content of less than 0.1%.

A method for producing a composite material structure contains a film attachment step (S2) of attaching a protective film to a molding member; a molding step (S3) of attaching a composite material which is a heating target to the molding member from above the protective film, accommodating the molding member in a pressure container, and molding a molded article; and a molded article removal step (S4) of removing the molded article from the molding member to which the protective film is attached. The protective film is a heat-resistance mold release film having a fluorine content of less than 0.1%.

The present disclosure refers to a method for manufacturing carbon fiber panels stiffened with omega stringers for the construction of aircraft structures, such as fuselage sections, wing panels, etc. One tubular pressure member is provided for each omega stringer of the structure to be manufactured, wherein the tubular pressure member is configured with the shape of the omega stringer. Each tubular pressure member is enclosed between the omega stringer and part of the laminate, and autoclave pressure is applied to the interior of the tubular pressure member, so that the tubular pressure member is used to consolidate the omega stringers and/or part of the laminate from the interior of these two elements, while these two elements are being co-cured or co-bonded in an autoclave. Imperfections on those internal surfaces such as resin wrinkles of the structure are reduced.

The present disclosure refers to a method for manufacturing carbon fiber panels stiffened with omega stringers for the construction of aircraft structures, such as fuselage sections, wing panels, etc. One tubular pressure member is provided for each omega stringer of the structure to be manufactured, wherein the tubular pressure member is configured with the shape of the omega stringer. Each tubular pressure member is enclosed between the omega stringer and part of the laminate, and autoclave pressure is applied to the interior of the tubular pressure member, so that the tubular pressure member is used to consolidate the omega stringers and/or part of the laminate from the interior of these two elements, while these two elements are being co-cured or co-bonded in an autoclave. Imperfections on those internal surfaces such as resin wrinkles of the structure are reduced.

A system for forming a composite component includes a close mold tool defining a cavity that corresponds to a shape of the composite component and configured to receive a composite material. The system further includes a perforated release film defining a plurality of openings and configured to be positioned on a surface of the composite material within the cavity. The system further includes a breather configured to be positioned on the perforated release film, to allow a vacuum to be applied to the composite material through the breather and the plurality of openings, and to allow pressurized fluid to be applied to the perforated release film through the breather.