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US 2014/0174632 A1Published application
Curable prepregs with surface openings
AssigneeCytec Industries Inc.
InventorsMark Roman, Stephen J Howard, Jack D Boyd, Scott Lucas
Life of this patent
Estimating the term…
Abstract
Curable prepregs possessing enhanced ability for the removal of gases from within prepregs and between prepreg plies in a prepreg layup prior to and/or during consolidation and curing. Each curable prepreg is a resin-impregnated, woven fabric that has been subjected to a treatment to create an array of openings in at least one major surface. The location of the openings is specific to the weave pattern of the fabric. Furthermore, when these prepregs are laid up and subjected to a debulking process to form a composite part, a shorter debulking time can be achieved as compared to using prepregs without the same surface openings.
Claims13
A method for fabricating a composite part wherein an overall cure time is reduced as a result of a decrease in debulking time prior to curing, said method comprising:
- laying up a plurality of uncured prepregs to form a composite layup;
- debulking the composite layup to remove air and volatiles therefrom by:
- (a) sealing a vacuum bag over the composite layup;
- (b) drawing a vacuum from within said vacuum bag;
- (c) applying pressure external to the vacuum bag;
- and (c) continuing to draw vacuum and to apply pressurize for a predetermined time interval;
- and
- curing the composite layup after debulking,
- wherein at least some of the uncured prepregs are porous prepregs with surface openings, each of said porous prepregs comprising:
- a woven fabric having two opposing faces and a weaving pattern in which one or more tows in a first weaving direction float over one or more tows in a second weaving direction, then pass under one or more tows in the second weaving direction,
- wherein a pocket is defined in the fabric surface when a first tow in the first weaving direction passes over a second tow in the second weaving direction then under an adjacent third tow in the second weaving direction, or when the first tow passes under a second tow in the second weaving direction then over an adjacent third tow in the second weaving direction, and the pocket location is defined by the portion of the first tow that is going up or going down between the adjacent second and third tows;
- a curable, hot-melt resin film covering one or both face(s) of the fabric and penetrating partially through the thickness of the fabric leaving an inner section of the fabric, in the thickness direction, substantially free of the resin film;
- and
- an array of openings in at least one of the resin films, each opening exposing at least a portion of the pocket in the fabric surface and configured to create a fluid flow path from the inner section of the fabric to at least one outer surface of the prepreg, or from at least one outer surface of the prepreg to the inner section, or from one outer surface of the prepreg to an opposite outer surface, or combination thereof.
11 more elements
A method for fabricating a composite part wherein an overall cure time is reduced as a result of a decrease in debulking time prior to curing, said method comprising:
- laying up a plurality of uncured prepregs to form a composite layup;
- debulking the composite layup to remove air and volatiles therefrom by:
- (a) sealing a vacuum bag over the composite layup;
- (b) drawing a vacuum from within said vacuum bag;
- (c) applying pressure external to the vacuum bag;
- and (c) continuing to draw vacuum and to apply pressurize for a predetermined time interval;
- and
- curing the composite layup after debulking,
- wherein at least some of the uncured prepregs are porous prepregs with surface openings, each of said porous prepregs comprising:
- a woven fabric having two opposing faces and a weaving pattern in which a tow in a first weaving direction passes over another tow in a second weaving direction, then pass under an adjacent tow in the second weaving direction, and interstices are defined between adjacent tows;
- a curable, hot-melt resin film covering one or both face(s) of the fabric and penetrating partially through the thickness of the fabric leaving an inner section of the fabric, in the thickness direction, substantially free of the resin film;
- and
- an array of openings in at least one of the resin films, each opening exposing an interstice in the fabric and configured to create a fluid flow path from the inner section of the fabric to at least one outer surface of the prepreg, or from at least one outer surface of the prepreg to the inner section, or from one outer surface of the prepreg to an opposite outer surface, or combination thereof.
10 more elements
A method for fabricating a composite part wherein an overall cure time is reduced as a result of a decrease in debulking time prior to curing, said method comprising:
- laying up a plurality of uncured prepregs to form a composite layup;
- debulking the composite layup to remove air and volatiles therefrom by:
- (a) sealing a vacuum bag over the composite layup;
- (b) drawing a vacuum from within said vacuum bag;
- (c) applying pressure external to the vacuum bag;
- and (c) continuing to draw vacuum and to apply pressurize for a predetermined time interval;
- and
- curing the composite layup after debulking,
- wherein at least some of the uncured prepregs are porous prepregs with surface openings, each of said porous prepregs being formed by a method comprising:
- (i) partially impregnating a woven fabric with a curable, hot-melt resin such that a continuous resin film covers each face of the fabric and penetrates partially through the thickness of the fabric leaving an inner section of the fabric, in the thickness direction, substantially free of said resin,
- wherein the woven fabric has two opposing faces and a weaving pattern in which one or more tows in a first weaving direction float over one or more tows in a second weaving direction, then pass under one or more tows in the second weaving direction,
- wherein a pocket is defined in a face of the fabric when a first tow in the first weaving direction passes over a second tow in the second weaving direction then under an adjacent third tow in the second weaving direction, or when the first tow passes under a second tow in the second weaving direction then over an adjacent third tow, and
- wherein the partially impregnated fabric comprises a plurality of enclosed air pockets, each air pocket coincides with a pocket in the fabric;
- and (ii) heating the partially impregnated fabric so that the resin film on at least one face of the fabric becomes flowable, and subsequently, portions of the resin film over the air pockets break open, thereby creating openings in the resin film that correspond to locations of the air pockets,
- wherein the openings are configured to provide fluid flow paths from the inner section of the fabric to at least one outer surface of the prepreg, or from at least one outer surface of the prepreg to the inner section, or from one outer surface of the prepreg to an opposite outer surface, or combination thereof.
12 more elements
Dependencies are inferred from the claim text.