Manufacture of FRP composites

Abstract

Techniques are provided for producing low-cost FRP composites which contain heavy tow fibres. Techniques are provided for uniform impregnation and efficient bonding of these heavy tow fibres which eliminates “racetracking,” thus resulting in cost-effective and well performing FRP composites.

1 . A method of manufacturing fibre reinforced plastics (FRP) composites, comprising: 
 impregnation of heavy tow fibres with a low viscosity resin.    
   
   
       2 . The method of  claim 1 , wherein the fibres comprise one of: 
 carbon fibres; and    glass fibres.    
   
   
       3 . The method of  claim 2 , wherein the carbon fibres are combined with at least one other type of fibres.  
   
   
       4 . The method of  claim 3 , wherein the at least one other type of fibres comprise glass fibres.  
   
   
       5 . The method of  claim 1 , wherein a tow of the fibres is equal to or greater than 24000 filaments.  
   
   
       6 . The method of  claim 1 , wherein the fibres are woven into fabric sheets with interlacing points.  
   
   
       7 . The method of  claim 6 , wherein the fabric sheets are multi-compacted.  
   
   
       8 . The method of  claim 6 , wherein a volume content of the fibres in the fabric sheets is less than 60%.  
   
   
       9 . The method of  claim 6 , wherein a volume content of the fibres in the fabric sheets is less than 30%.  
   
   
       10 . The method of  claim 1 , wherein the resin, at a time of impregnation, has a viscosity less than 50 mPa*s.  
   
   
       11 . The method of  claim 10 , wherein the resin is a thermoplastic resin.  
   
   
       12 . The method of  claim 1 , wherein the impregnation is carried out by injection of the resin into a fabric sheet comprising the fibres.  
   
   
       13 . The method of  claim 12 , wherein an injection point of the resin is directly in the fabric area.  
   
   
       14 . The method of  claim 12 , wherein the resin is injected with stepwise increments of pressure such that a pressure at a flow front of the resin is balanced before a pressure increment.  
   
   
       15 . The method of  claim 12 , wherein a flow front of the injected resin is against gravity.  
   
   
       16 . The method of  claim 12 , wherein a flow direction of the injected resin is not perpendicular to an orientation of the fibres.  
   
   
       17 . The method of  claim 12 , wherein the fabric is clamped at edges of a mould before the resin injection.  
   
   
       18 . The method of  claim 17 , wherein the edges of the mould have a reduced cavity high.  
   
   
       19 . The method of  claim 18 , wherein a fibre volume fraction at the reduced cavity high is no more than 55%.  
   
   
       20 . The method of  claim 18 , wherein a fibre volume fraction at the reduced cavity high is no more than 50%.  
   
   
       21 . A FRP composite product obtained by performing the method of  claim 1 .  
   
   
       22 . The FRP composite product of  claim 21 , wherein a volume content of the fibres in the composite is less than 60%.  
   
   
       23 . The FRP composite product of  claim 21 , wherein a volume content of the fibres in the composite is less than 30%.  
   
   
       24 . An apparatus for the manufacture of FRP by performing the method of  claim 1 .  
   
   
       25 . A method of manufacturing fibre reinforced plastics (FRP) composites, comprising: 
 impregnation of fibres with resin from an injection side towards a downstream side, wherein a pressure on the injection side is incremented stepwise.    
   
   
       26 . The method of  claim 25 , wherein a time interval in between a first pressure increment and a second pressure increment is such that a pressure at a flow front is balanced across the downstream side before the second pressure increment.  
   
   
       27 . The method of  claim 25 , wherein the fibres comprise one of: 
 carbon fibres; and    glass fibres.    
   
   
       28 . An apparatus for manufacturing FRP composites, comprising: 
 a reduced cavity high at edges of a mould wherein fibres or fibre fabric is placed;    a clamping mechanism to prevent displacement of the fibres or the fibre fabric; and    a pressure ramp injection system, wherein a resin is injected into the mould under stepwise increments of pressure.    
   
   
       29 . The apparatus of  claim 28 , wherein the resin is injected directly into the fibres or the fibre fabric under the stepwise increments of pressure.