Bast fibers for plastics reinforcement and preparation method thereof

Abstract

The present invention refers to bast fibers for plastics reinforcement and preparation method thereof. The bast fibers are composed of the following components by weight ratio; 100 pts.wt. chopped bast fibers, 0.1˜100 pts.wt. bast fiber treating agent, 1˜10 pts.wt. Functional Polyolefin wax, 0.1˜10 pts.wt. coupling agent and 0.1˜0.5 pts.wt. antioxidant. The method includes the steps of: firstly, cut chopped bast fibers and soak them in sodium hydroxide solution, agitate the mixture, after rinse and drying of water, soak the fibers in the aqueous solution of bast fiber treating agent, then dry them and obtain surface-treated chopped bast fibers; secondly, add in order the chopped fibers, the coupling agent, the Functional Polyolefin wax and the antioxidant to a preheated kneader, agitate the mixture and thus obtain bast fibers for plastics reinforcement. Chopped bast fibers according to the invention present good color, rigidity and heat resistance, as well as excellent compatibility with plastics, and can be used in the preparation of high-performance short-bast-fiber\plastic composites, as reinforcement in the plastic matrix.

1 . Bast fibers for plastics reinforcement, characterized in that: the bast fibers for plastics reinforcement consists of the following components by weight ratio: 
       
         
           
                 
                 
                 
                 
               
                     
                 
                     
                   Chopped bast fibers 
                   100 
                   pts.wt. 
                 
                     
                   Bast fiber treating agent 
                   0.1~100  
                   pts.wt. 
                 
                     
                   Functional Polyolefin wax 
                   1~10 
                   pts.wt. 
                 
                     
                   Coupling agent 
                   0.1~10 
                   pts.wt. 
                 
                     
                   Antioxidants 
                   0.1~0.5 
                   pts.wt. 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
               
            
           
         
       
     
     
         2 . Bast fibers for plastics reinforcement according to  claim 1 , wherein the chopped bast fibers are chosen from at least one of the following fibers: ramie fiber, flax fiber, agave fiber, jute fiber and agotai fiber. 
     
     
         3 . Bast fibers for plastics reinforcement according to  claim 1 , wherein the bast fiber treating agent is urea-formaldehyde resin prepolymer, trimethylol melamine resin or hexamethylol melamine resin. 
     
     
         4 . Bast fibers for plastics reinforcement according to  claim 1 , wherein the Functional Polyolefin wax is chosen from at least one of the following components: metallocene polyethylene wax, metallocene polypropylene wax, oxidized metallocene polyolefin wax and maleic-anhydride-grafted metallocene polyolefin wax. 
     
     
         5 . Bast fibers for plastics reinforcement according to  claim 1 , wherein the coupling agent is chosen from at least one of the following components: silane coupling agent, titanium coupling agent, aluminum coupling agent, isocyanate coupling agent and rare-earth coupling agent. 
     
     
         6 . Bast fibers for plastics reinforcement according to  claim 1 , wherein the antioxidant is composed of antioxidant 1010 and antioxidant 168, with a mass ratio of 2:1 between the two. 
     
     
         7 . Method for preparing the bast fibers for plastics reinforcement according to  claim 1 , characterized in comprising the following steps:
 (1) Cut bast fibers to a length of 1˜20 mm to obtain chopped bast fibers; soak the chopped bast fibers in sodium hydroxide solution and agitate the mixture for 1˜20 mins, after rinse with water and drying, soak them in the aqueous solution of bast fiber treating agent at a temperature of 80˜90° C. for 5 mins˜30 mins, then dry them until the solution is exhausted by the bast fibers and thus obtain surface-treated chopped bast fibers;   (2) Add in order the surface-treated chopped bast fibers, the coupling agent, the Functional Polyolefin wax and the antioxidant to a kneader preheated to 70˜80° C. , agitate the mixture, and then obtain bast fibers for plastics reinforcement.   
     
     
         8 . Method according to  claim 7 , wherein in step (1), the mass concentration of the sodium hydroxide solution is of 1%˜10%; the mass concentration of the bast fiber treating agent is of 10%˜50%; the rinse is of centrifugal type; the dry is meant to dry the fibers to the extent that the latter has a water content of 8%˜15%. 
     
     
         9 . Method according to  claim 7 , wherein in step (1), the drying is of the type of vacuum drying at a temperature of 90˜150° C. and to the extent that the fibers have a water content of less than 1%; the rinse is meant to rinse the fibers with water until the pH is between 7.0˜9.0. 
     
     
         10 . Method according to  claim 7 , wherein in step (2), the agitation duration is 5˜10 mins; the agitation speed is 50˜300 rpm.