Milled carbon fiber

Abstract

A milled carbon fiber is made of a carbon fiber, which is coated with a sizing at an amount X between 0.05 and 0.30 weight %. The sizing is formed of a heat resistant polymer or a precursor of the heat resistant polymer. The amount X of the sizing is expressed with a following formula: X = w o - w 1 w o × 100 where W 0 is the weight of the carbon fiber with the sizing, and W 1 is the weight of the carbon fiber without the sizing.

1 . A milled carbon fiber formed of a carbon fiber coated with a sizing at an amount X between 0.05 and 0.30 weight %, said sizing being formed of a heat resistant polymer or a precursor of the heat resistant polymer, said amount X being expressed with a following formula: 
       
         
           
             
               X 
               = 
               
                 
                   
                     
                       w 
                       o 
                     
                     - 
                     
                       w 
                       1 
                     
                   
                   
                     w 
                     o 
                   
                 
                 × 
                 100 
               
             
           
         
         where W 0  is a weight of the carbon fiber with the sizing, and W 1  is a weight of a carbon fiber without the sizing, 
         wherein said heat resistant polymer is applied on the carbon fiber in a form of at least one of an aqueous solution, an aqueous dispersion or an aqueous emulsion. 
       
     
     
         2 . (canceled) 
     
     
         3 . The milled carbon fiber according to  claim 1 , wherein said heat resistant polymer is selected from a group consisting of a phenol resin, a melamine resin, a urea resin, a polyimide resin, a polyetherimide resin, a polysulfone resin, a polyethersulfone resin, a polyetheretherketone resin, a polyetherketoneketone resin, a polyamide resin, and a polyphenylenesulfide resin. 
     
     
         4 . The milled carbon fiber according to  claim 1 , wherein said carbon fiber is produced in a continuous process including carbonization, surface treatment, sizing application and winding. 
     
     
         5 . The milled carbon fiber according to  claim 1 , wherein said carbon fiber has a length of 2 mm or less. 
     
     
         6 . The milled carbon fiber according to  claim 1 , wherein said heat resistant polymer has a thermal degradation onset temperature higher than 300 degrees Celsius. 
     
     
         7 . The milled carbon fiber according to  claim 1 , wherein said heat resistant polymer has a 30% weight reduction temperature higher than 350 degrees Celsius. 
     
     
         8 . The milled carbon fiber according to  claim 1 , wherein said carbon fiber has an interfacial shear strength A greater than an interfacial shear strength B of the carbon fiber without the sizing to satisfy a relation of A>B, said interfacial shear strength A and B being measured with a single fiber fragmentation test. 
     
     
         9 . The milled carbon fiber according to  claim 1 , wherein said carbon fiber is produced through a fabrication process including a drying process at a temperature higher than 200 degrees Celsius for longer than 6 seconds. 
     
     
         10 . The milled carbon fiber according to  claim 1  wherein the sizing amount X is greater than or equal to 0.05 and less than 0.1. 
     
     
         11 . The milled carbon fiber according to  claim 1  exhibiting a drape value of less than 2 cm. 
     
     
         12 . The milled carbon fiber according to  claim 1  exhibiting a rubbing fuzz count A when the sizing amount X is greater than or equal to 0.05 and less than 0.1 and a rubbing fuzz count B when the sizing amount X is greater than or equal to 0.1 and less than or equal to 0.3, wherein A is less than B. 
     
     
         13 . A milled carbon fiber formed of a carbon fiber coated with a sizing at an amount X between 0.05 and 0.30 weight %, said sizing being formed of a heat resistant polymer or a precursor of the heat resistant polymer, said amount X being expressed with a following formula: 
       
         
           
             
               X 
               = 
               
                 
                   
                     
                       w 
                       o 
                     
                     - 
                     
                       w 
                       1 
                     
                   
                   
                     w 
                     o 
                   
                 
                 × 
                 100 
               
             
           
         
       
       where W 0  is a weight of the carbon fiber with the sizing, and W 1  is a weight of a carbon fiber without the sizing,
 wherein said heat resistant polymer has a thermal degradation onset temperature higher than 300 degrees Celsius. 
 
     
     
         14 . A milled carbon fiber formed of a carbon fiber coated with a sizing at an amount X between 0.05 and 0.30 weight %, said sizing being formed of a heat resistant polymer or a precursor of the heat resistant polymer, said amount X being expressed with a following formula: 
       
         
           
             
               X 
               = 
               
                 
                   
                     
                       w 
                       o 
                     
                     - 
                     
                       w 
                       1 
                     
                   
                   
                     w 
                     o 
                   
                 
                 × 
                 100 
               
             
           
         
       
       where W 0  is a weight of the carbon fiber with the sizing, and W 1  is a weight of a carbon fiber without the sizing,
 wherein said carbon fiber has an interfacial shear strength A greater than an interfacial shear strength B of the carbon fiber without the sizing to satisfy a relation of A>B, said interfacial shear strength A and B being measured with a single fiber fragmentation test.