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A method of vacuum moulding a composite material in which laid-up prepregs uncured resin and reinforcing filaments are placed on a heated former and covered with a sheet of a microporous film material a breather material and an impermeable membrane. The volume enclosed by the membrane is evacuated a

A method of vacuum moulding a composite material in which laid-up prepregs uncured resin and reinforcing filaments are placed on a heated former and covered with a sheet of a microporous film material a breather material and an impermeable membrane. The volume enclosed by the membrane is evacuated and the temperature of the mould increased to firstly outgas the resin and mould the prepregs to the shape of the former and finally cure the resin. The arrangement ensures excellent access of the prepregs to the vacuum during the moulding operation, thereby in turn ensuring that the resultant moulded article has very low porosity as a result of gas or vapor inclusions or is porosity-free.

대표청구항 ▼

1. A method of vacuum moulding an article from a filament reinforced composite material comprising the steps of (1) laying up, on a suitable former, a plurality of prepregs, each comprising reinforcing filaments enclosed in an uncured resin, (2) overlaying at least a major portion of the exposed

1. A method of vacuum moulding an article from a filament reinforced composite material comprising the steps of (1) laying up, on a suitable former, a plurality of prepregs, each comprising reinforcing filaments enclosed in an uncured resin, (2) overlaying at least a major portion of the exposed surface of said laid-up prepregs with at least one sheet of a microporous film material which acts as a barrier to particles which are greater than 0.04 microns in size and which film is premeable to gases and vapours but impermeable to liquid resin, (3) overlaying at least a major portion of said sheet of microporous film material with a breather material, (4) enclosing said laid-up prepregs, said at least one sheet of microporous film material and said breather material with a gas impermeable membrane, (5) evacuating the volume enclosed by said membrane and maintaining said prepregs at room temperature a sufficient time to preconoslidate said prepregs (6) then gradaully increasing the temperature of said prepregs to a temperature which is high enough to cause the resin in said prepregs to outgas and become sufficiently mobile to permit the coalescing and moulding of said prepregs to take place and for said resin to subsequently gel but low enough for outgasing to be substantially completed before said gelling commences, and holding said temperature for a sufficient time for said outgasing, moulding and gelling to occur, subsequently (7)gradually increasing the temperature of said prepregs to 45 centrigrade degrees higher than the temperature of outgassing step (6). and holding said increased temperature a sufficient time to cure said resin, and then (8) reducing the temperature followed by discontinuing said evacuating and removing the resultant article from said former. 2. A method of vacuum moulding an article as claimed in claim 1 wherein a release material is interposed between the surface of said laid-up prepregs and said sheet of microporous film material. 3. A method of vacuum moulding an article as claimed in claim 1 wherein a release material is interposed between the surface of said laid-up prepregs and said former. 4. A method of vacuum moulding an article as claimed in claim 1 wherein said filaments are of carbon. 5. A method of vacuum moulding an article as claimed in claim 1 wherein said uncured resin is an epoxy resin. 6. A method of vacuum moulding an article from a filament reinforced composite material comprising the steps of (1) laying up, on a suitable former, a prepreg comprising reinforcing filaments enclosed in an uncured resin, (2) overlaying at least a major portion of the exposed surface of said laid-up prepreg with at least one sheet of a microporous film material which acts as a barrier to particles which are greater than 0.04 microns in size and which film is permeable to gases and vapours but impermeable to liquid resin, (3) overlaying at least a major portion of said sheet of microporous film material with a breather material, (4) enclosing said laid-up prepreg, said at least one sheet of microporous film material and said breather material with a gas impermeable membrane, (5) evacuating the volume enclosed by said membrane and maintaining said prepreg at room temperature a sufficient time to preconsolidate said prepreg, (6) repeating steps (1) through (5) to lay up and preconsolidate a plurality of said prepregs, (7) then gradually increasing the temperature of said prepregs to a temperature which is high enough to cause the resin in said prepregs to outgas and become sufficiently mobile to permit the coalescing and moulding of said prepregs to take place and for said resin to subsequently gel but low enough for outgassing to be substantially completed before said gelling commences, and holding said temperature for a sufficient time for said outgassing, moulding and gelling to occur, subsequently, (8) gradually increasing the temperature of said prepregs to a temperature about 45 centigrade degrees higher than the temperature of outgassing step (7) and holding said increased temperature a sufficient time to cure said resin, and then, (9) reducing the temperature followed by discontinuing said evacuating and removing the resultant molded article from said former.