Continuous fiber granulate and procedure and device for manufacturing a long-fiber granulate

Abstract

Continuous strand pellets made of particles, in which reinforcing staple fibers are arranged in a thermoplastic matrix in a helical manner, are provided. The reinforcing staple fibers and the molten matrix material are situated in a peripheral area of the particles and, together with unmolten thermoplastic staple fibers, are present in a core area of the particles. A method for producing the continuous strand pellets from a staple fiber mixture of thermoplastic fibers and reinforcing fibers includes feeding the staple fiber mixture through a preheating zone and then drawing the staple fiber mixture through a heating nozzle to form a strand, which after rotating and consolidation by cooling, is cut into continuous strand pellets.

1 . Procedure for manufacturing continuous fiber granulate out of a staple fiber mixture of thermoplastic fibers and reinforcing fibers, in which a fiber strip comprised of the staple fiber mixture is guided through a preheating zone, then extruded through a heating nozzle into a strand, and the strand is cut into continuous fiber granulate sections after rotation and consolidation via cooling, characterized by the fact that the strand is first cooled, and then rotated, withdrawn and subsequently allowed to rotate freely as it is cut into sections with no impediment.  
     
     
         2 . Procedure according to  claim 1 , characterized by the fact that the thermoplastic fiber portion of the fiber strip is only melted in a sheath area in the preheating zone.  
     
     
         3 . Procedure according to  claim 1  or  2 , characterized by the fact that a ratio of speed to withdrawal rate ranging from 10 to 150 revolutions per meter is used.  
     
     
         4 . Procedure according to one of  claims 1  to  3 , characterized by the fact that the percentage of reinforcing fibers in the fiber strip ranges from 10 to 80%w/w.  
     
     
         5 . Procedure according to one of  claims 1  to  4 , characterized by the fact that an average reinforcing fiber length in the fiber strip ranging from 30 to 200 mm is selected.  
     
     
         6 . Procedure according to one of  claims 1  to  5 , characterized by the fact that a fineness of the fiber strip ranging from 5 to 30 ktex is selected.  
     
     
         7 . Continuous fiber granulate consisting of granulate particles, in which reinforcing staple fibers are helically arranged in a thermoplastic matrix, characterized by the fact that the reinforcing staple fibers are located in a sheathed zone ( 14 ) of the particles ( 15 ) along with the melted matrix material ( 12 ), and in a core zone ( 13 ) of the particles along with unmelted thermoplastic staple fibers.  
     
     
         8 . Continuous fiber granulate according to  claim 7 , characterized by the fact that the particles are strand sections ( 15 ), and the length of their reinforcing fibers ( 11 ) is greater than the length of the strand sections.  
     
     
         9 . Continuous fiber granulate according to  claim 7  or  8 , characterized by the fact that the reinforcing staple fibers are natural fibers, synthetic fibers or mineral fibers.  
     
     
         10 . Continuous fiber granulate according to one of  claims 7  to  9 , characterized by the fact that the diameter of the granulate particles ( 15 ) ranges from 1 to 10 mm.  
     
     
         11 . Continuous fiber granulate according to one of  claims 7  to  10 , characterized by the fact that the percentage of reinforcing fibers ( 11 ) in the granulate particle ( 15 ) ranges from 10 to 80%w/w.  
     
     
         12 . Continuous fiber granulate according to one of  claims 7  to  11 , characterized by the fact that the material of the matrix and thermoplastic fibers preferably consists of polypropylene, polyethylene or polyamide.  
     
     
         13 . Device for manufacturing continuous fiber granulate out of a staple fiber strip consisting of thermoplastic fibers and reinforcing fibers, with a preheating zone ( 4 ), a heating nozzle ( 5 ), a cooling zone ( 6 ), a rotating element ( 7 ) and a granulator ( 8 ), characterized by the fact that the rotating element ( 7 ) that generates the strand torsion is arranged behind the cooling zone ( 6 ) and designed as a withdrawal element for the strand, and that the granulator ( 8 ) exerts no torque, or at most a torque without permanent reverse rotation, on the strand during the separation process.  
     
     
         14 . Device according to  claim 13 , characterized by the fact that the preheating zone ( 4 ) is set up only for melting a sheath zone of the staple fiber strip.