Production of uniformly resin impregnated carbon fiber ribbon

Claim 2

AN IMPROVED PROCESS FOR THE PRODUCTION OF A UNIFORMLY RESIN IMPREGNATED RIBBON OF A CARBONACEOUS FIBROUS MATERIAL WHICH IS SUITABLE FOR USE IN THE MANUFACTURE OF CARBON FIBER REINFORCED COMPOSITE STRUCTURES COMPRISING: A. CONTINUOUSLY CONVEYING TO AN IMPREGNATION ZONE TO CARBONACEOUS FIBROUS RIBBON CONTAINING AT LEAST ABOUT 90 PERCENT CARBON BY WEIGHT, B. FORCING A LIQUID SOLVENTLESS SYSTEM HAVING A VISCOSITY OF ABOUT 500 TO 10,000 CPS, COMPRISING AN A-STAGE THERMOSETTING RESIN INTO INTIMATE ASSOCIATION WITH SAID CARBONACEOUS FIBROUS RIBBON WHILE PRESENT IN SAID IMPREGNATION ZONE, C. INTERPOSING SAID RIBBON WHILE IN INTIMATE ASSOCIATION WITH SAID SOLVENTLESS SYSTEM BETWEEN THE OUTER SURFACES OF A PAIR OF FLEXIBLE ENDLESS BELTS HAVING A NON POROUS SURFACE AND A WIDTH GREATER THAN THAT OF SAID RIBBON, D. CONNTINUOUSLY PASSING SAID RIBBON IN THE DIRECTION OF ITS LENGTH WHILE INTERPOSED BETWEEN SAID FLEXIBLE ENDLESS BELTS THROUGH A SUBSTANTIALLY ENCLOSED HEATING ZONE PROVIDED WITH A HEATED GASEOUS ATMOSPHERE WHILE SUBSTANTIALLY SUSPENDED THEREIN WHEREIN SAID BELTS AND SAID RIBBON ARE LOOPED IN A SINGLE WRAP ABOUT EACH OF A MULTIPLICITY OF ROTATING PARALLEL ROLLERS WHEREIN THE INNER SURFACES OF SAID BELTS ARE IN ALTERNATING CONTACT WITH SAID ROLLERS AS SAID BELTS AND SAID RIBBON PROGRESS THROUGH SAID HEATING ZONE WITH SAID RIBBON BEING OUT OF CONTACT WITH SAID ROLLERS AND WHEREIN SAID THERMOSETTING RESIN IN INTIMATE ASSOCIATION WITH SAID RIBBON IS CONVERTED TO A B-STAGE CONSISTENCY. E. CONTINUOUSLY WITHDRAWING SAID RIBBON FROM SAID HEATING ZONE WHILE INTERPOSED BETWEEN SAID OUTER SURFACES OF SAID PAIR OF FLEXIBLE ENDLESS BELTS AND WHILE SAID THERMOSETTING RESIN IN INTIMATE ASSOCIATION WITH SAID RIBBON REMAINS IN A B-STAGE CONSISTENCY, AND F. SEPARATING SAID RESULTING RESIN IMPREGNATED CARBONACEOUS FIBROUS RIBBON FROM SAID FLEXIBLE ENDLESS BELTS.

Claim 3

An improved process according to claim 1 wherein said carbonaceous fibrous ribbon comprises a plurality of substantially parallel multifilament fiber bundles.

Claim 4

An improved process according to claim 1 wherein said carbonaceous fibrous ribbon is a tow.

Claim 5

An improved process according to claim 1 wherein said carbonaceous fibrous ribbon contains at least about 95 percent carbon by weight and exhibits a predominantly graphitic X-ray diffraction pattern.

Claim 6

An improved process according to claim 1 wherein said liquid solventless system comprising an A-stage thermosetting resin has a viscosity of about 1,000 to 3,000 cps.

Claim 7

An improved process according to claim 1 wherein said solventless system comprising an A-stage thermosetting resin is forced into intimate association with said carbonaceous fibrous ribbon by passing said ribbon bearing said system upon its surface through a pair of rotating parallel nip rollers.

Claim 8

An improved process according to claim 1 wherein said solventless system comprises an A-stage epoxy resin and a curing agent for said resin.

Claim 9

An improved process according to claim 7 wherein said epoxy resin is a condensation product of bisphenol A and epichlorohydrin.

Claim 10

An improved process according to claim 7 wherein said epoxy resin is an epoxy novolac resin formed by the reacting of epichlorohydrin with a phenol-formaldehyde resin.

Claim 11

An improved process according to claim 1 wherein said resulting uniformly resin impregnated carbonaceous fibrous ribbon contains about 35 to 55 percent B-stage thermosetting resin by volume, and about 45 to 65 percent carbon fiber by volume.

Claim 12

An improved process for the production of a uniformly resin impregnated ribbon of a carbonaceous fibrous material which is suitable for use in the manufacture of carbon fiber reinforced composite structures comprising: a. continuously conveying to an impregnation zone a carbonaceous fibrous ribbon containing at least about 90 percent carbon by weight, b. forcing a liquid solventless system having a viscosity of about 1,000 to 3,000 cps. comprising an A-stage thermosetting epoxy resin and a curing agent for said resin into intimate association with said carbonaceous fibrous ribbon while present in said impregnation zone, c. interposing said ribbon while in intimate association with said solventless system between the outer surfaces of a pair of flexible endless belts having a non porous surface and a width greater than that of said ribbon, d. continuously passing said ribbon in the direction of its length while interposed between said flexible endless belts through a substantially enclosed heating zone provided with a heated gaseous atmosphere at a temperature of about 75* to 175* C. while substantially suspended therein wherein said belts and said ribbon are looped in a single wrap about each of a multiplicity of rotating parallel rollers wherein the inner surfaces of said belts are in alternating contact with said rollers as said belts and said ribbon progress through said heating zone with said ribbon being out of contact with said rollers and wherein said thermosetting epoxy resin in intimate association with said ribbon is converted to a B-stage consistency, e. continuously withdrawing said ribbon from said heating zone while interposed between said outer surfaces of said pair of flexible endless belts and while said thermosetting epoxy resin in intimate aSsociation with said ribbon remains in a B-stage consistency, and f. separating said resulting epoxy resin impregnated carbonaceous fibrous ribbon from said flexible endless belts.

Claim 13

An improved process for the production of a uniformly resin impregnated ribbon of a carbonaceous fibrous material which is suitable for use in the manufacture of carbon fiber reinforced composite structures comprising: a. continuously conveying to an impregnation zone a carbonaceous fibrous ribbon containing at least about 90 percent carbon by weight, b. forcing a liquid solventless system having a viscosity of about 1,000 to 3,000 cps. comprising an A-stage thermosetting epoxy resin and a curing agent for said resin into intimate association with said carbonaceous fibrous ribbon while present in said impregnation zone, c. interposing said ribbon while in intimate association with said solventless system between the outer surfaces of a pair of flexible endless belts having a non porous surface and a width greater than that of said ribbon, d. continuously passing said ribbon in the direction of its length while interposed between said flexible endless belts through a substantially enclosed heating zone provided with a heated gaseous atmosphere at a temperature of about 75* to 175* C. while substantially suspended therein wherein said belts and said ribbon are looped in a single wrap about each of a multiplicity of rotating parallel rollers wherein the inner surfaces of said belts are in alternating contact with said rollers as said belts and said ribbon progress through said heating zone with said ribbon being out of contact with said rollers and wherein said thermosetting epoxy resin in intimate association with said ribbon is converted to a B-stage consistency, e. continuously withdrawing said ribbon from said heating zone while interposed between said outer surfaces of said pair of flexible endless belts and while said thermosetting epoxy resin in intimate aSsociation with said ribbon remains in a B-stage consistency, and f. separating said resulting epoxy resin impregnated carbonaceous fibrous ribbon from said flexible endless belts.

Claim 14

An improved process according to claim 11 wherein said carbonaceous fibrous ribbon comprises a plurality of substantially parallel multifilament fiber bundles.

Claim 15

An improved process according to claim 11 wherein said carbonaceous fibrous ribbon is a tow.

Claim 16

An improved process according to claim 11 wherein said carbonaceous fibrous ribbon contains at least about 95 percent carbon by weight and exhibits a predominantly graphitic X-ray diffraction pattern.

Claim 17

An improved process according to claim 11 wherein said heated gaseous atmosphere provided within said heating zone has a temperature of about 100* to 150* C.

Claim 18

An improved process according to claim 11 wherein said solventless system comprising an A-stage thermosetting epoxy resin and a curing agent for said resin is forced into intimate association with said carbonaceous fibrous ribbon by passing said ribbon bearing said system upon its surface through a pair of rotating parallel nip rollers.

Claim 19

An improved process according to claim 11 wherein said epoxy resin is a condensation product of bisphenol A and epichlorohydrin.

Claim 20

An improved process according to claim 1 wherein said epoxy resin is an epoxy novolac resin formed by the reacting of epichlorohydrin with a phenol-formaldehyde resin.

Claim 21

An improved process according to claim 11 wherein said resulting uniformly epoxy resin impregnated carbonaceous fibrous ribbon contains about 35 to 55 percent B-stage thermosetting epoxy resin by volume, and about 45 to 65 percent carbon fiber by volume.