Method for splitting carbon fiber tow

Abstract

Provided is a method for splitting a carbon fiber tow, which comprises heating a carbon fiber tow sized with a first sizing material to soften the first sizing material and form a spread carbon fiber tow; passing the spread carbon fiber tow through at least one splitter and corresponding cutter to obtain multiple carbon fiber strands spaced apart; and sizing the carbon fiber strands with a second sizing material. With the method, multiple small carbon fiber tows having better tensile strength and/or modulus than the commercially available small carbon fiber tow products can be obtained. Products made of the small carbon fiber tows obtained by the present invention are lighter but stronger, and the production cost is relatively reduced. The present invention also achieves the purpose of energy saving and carbon reduction.

What is claimed is: 
     
         1 . A method for splitting a carbon fiber tow, comprising:
 (A) providing a carbon fiber tow comprising multiple carbon filaments sized with a solution containing a first sizing material;   (B) passing the carbon fiber tow through a first heating device to heat the carbon fiber tow at a temperature of between 45° C. and 140° C., so as to soften the first sizing material and form a spread carbon fiber tow;   (C) adjusting the tension of the spread carbon fiber tow;   (D) passing the spread carbon fiber tow through at least one splitter to obtain a plurality of multiple carbon fiber strands spaced apart;   (E) passing the spread carbon fiber tow through at least one cutter to cut the carbon filaments connected between the carbon fiber strands;   (F) adjusting the tension of the carbon fiber strands;   (G) sizing the carbon fiber strands with a solution containing a second sizing material to obtain multiple sized carbon fiber strands; and   (H) passing the multiple sized carbon fiber strands through a second heating device to heat the sized carbon fiber strands to obtain multiple split carbon fiber tows.   
     
     
         2 . The method as claimed in  claim 1 , wherein the spread carbon fiber tow has a maximum width for the carbon fiber tow. 
     
     
         3 . The method as claimed in  claim 1 , the step (B) is repeated multiple times to obtain the spread carbon fiber tow. 
     
     
         4 . The method as claimed in  claim 1 , further comprising, in the step (H), passing the multiple sized carbon fiber strands through a cooling device after passing the multiple sized carbon fiber strands through a second heating device. 
     
     
         5 . The method as claimed in  claim 1 , further comprising adjusting the width of the multiple sized carbon fiber tows. 
     
     
         6 . The method as claimed in  claim 4 , further comprising adjusting the width of the multiple sized carbon fiber tows. 
     
     
         7 . The method as claimed in  claim 1 , further comprising, after the step (E) and before the step (F), guiding each of the carbon fiber strands to one of guiding rollers respectively, wherein any two adjacent carbon fiber strands were guided to guiding rollers at different height level. 
     
     
         8 . The method as claimed in  claim 1 , wherein the first sizing material is a thermosetting material. 
     
     
         9 . The method as claimed in  claim 1 , wherein the second sizing material comprises a thermoplastic material or a thermosetting material. 
     
     
         10 . The method as claimed in  claim 9 , wherein the thermoplastic material is selected from a group consisting of an acrylonitrile butadiene styrene (ABS), a polypropylene (PP), a polyethylene (PE), a polycarbonate (PC), a polyurethane (PU), a polystyrene (PS), a polyethylene terephthalate (PET), and a polyetheretherketone (PEEK). 
     
     
         11 . The method as claimed in  claim 9 , wherein the thermosetting material is an epoxy resin. 
     
     
         12 . The method as claimed in  claim 1 , wherein the carbon fiber tow is heated at a temperature of between 80° C. and 120° C. in Step (B). 
     
     
         13 . The method as claimed in  claim 1 , wherein the multiple sized carbon fiber strands are heated at a temperature of between 80° C. and 120° C. in Step (H). 
     
     
         14 . The method as claimed in  claim 4 , wherein the multiple sized carbon fiber strands are cooled at a temperature of between 2° C. and 10° C. 
     
     
         15 . The method as claimed in  claim 6 , wherein the multiple sized carbon fiber strands are cooled at a temperature of between 2° C. and 10° C. 
     
     
         16 . The method as claimed in  claim 1 , wherein the at least one splitter is made of metal. 
     
     
         17 . The method as claimed in  claim 1 , wherein the at least one splitter is configured to equally split the spread carbon fiber tow. 
     
     
         18 . The method as claimed in  claim 1 , wherein the at least one cutter is a circular saw blade. 
     
     
         19 . The method as claimed in  claim 1 , wherein the split carbon fiber tow has a breaking strength of 16.0 kgf or higher and a breaking elongation of 4.8% or higher. 
     
     
         20 . The method as claimed in  claim 19 , wherein the split carbon fiber tow has a length of about 5000 meters.