Novel strengthening composite

Abstract

According to the invention, in the unidirectional strengthening composite ( 1 ) based on thread laps, said thread laps consist of a first lap ( 2 ) of mutually parallel strengthening threads ( 3 ), a second lap ( 4 ) of bonding threads ( 5 ) composed of a fibrous core coated with a thermoplastic and running transversely to the threads ( 3 ) of the first lap ( 2 ), being crossed without interlacing, said strengthening threads ( 3 ) of the first lap ( 2 ) being bonded, at least locally, to the bonding threads ( 5 ) of the second lap ( 4 ) by fusion of the thermoplastic, and optionally a third lap ( 6 ) of strengthening threads ( 7 ) parallel to one another and to those of the first lap ( 2 ) and bonded, at least locally, to the coated bonding threads ( 5 ) by fusion of the thermoplastic, the coated bonding threads ( 5 ) of the second lap ( 4 ) being trapped between the strengthening threads ( 3 ) of the first lap ( 2 ) and the strengthening threads ( 7 ) of the third lap ( 6 ).

What is claimed is:  
     
         1 . A unidirectional strengthening composite ( 1 ) based on thread laps, wherein said thread laps consist of: 
 a first lap ( 2 ) of mutually parallel strengthening threads ( 3 ),    a second lap ( 4 ) of bonding threads ( 5 ) composed of a fibrous core coated with a thermoplastic and running transversely to the threads ( 3 ) of the first lap ( 2 ), being crossed without interlacing, said strengthening threads ( 3 ) of the first lap ( 2 ) being bonded, at least locally, to the bonding threads ( 5 ) of the second lap ( 4 ) by fusion of the thermoplastic,    and optionally a third lap ( 6 ) of strengthening threads ( 7 ) parallel to one another and to those of the first lap ( 2 ) and bonded, at least locally, to the coated bonding threads ( 5 ) by fusion of the thermoplastic, the coated bonding threads ( 5 ) of the second lap ( 4 ) being trapped between the strengthening threads ( 3 ) of the first lap ( 2 ) and the strengthening threads ( 7 ) of the third lap ( 6 ).    
     
     
         2 . A composite according to  claim 1  wherein at least 95% by weight of the strengthening composite ( 1 ) consists of strengthening threads ( 3 ,  7 ).  
     
     
         3 . A composite according to  claim 1  or  2  wherein the strengthening threads ( 3 ,  7 ) have a coverage of approximately 100%.  
     
     
         4 . A strengthening composite ( 1 ) according to one of  claims 1  to  3  wherein the coated bonding threads ( 5 ) have a titer of between 30 and 600 tex.  
     
     
         5 . A strengthening composite ( 1 ) according to one of  claims 1  to  3  wherein the coating of thermoplastic on the coated bonding threads ( 5 ) is between 10 and 500 g per 1000 linear meters.  
     
     
         6 . A strengthening composite ( 1 ) according to one of  claims 1  to  3  wherein the strengthening threads ( 3 ) of the first lap ( 2 ) are bulked or texturized.  
     
     
         7 . A strengthening composite ( 1 ) according to one of  claims 1  to  3  wherein the strengthening threads ( 3 ) of the first lap ( 2 ) are at least partially covered with an anti-tear thermoplastic powder ( 8 ).  
     
     
         8 . A strengthening composite ( 1 ) according to  claim 7  wherein the anti-tear thermoplastic powder ( 8 ) is covered by a sheet ( 9 ) for imparting a particular appearance, which is intimately bonded to the product ( 1 ) by at least partial fusion of the anti-tear powder ( 8 ).  
     
     
         9 . A strengthening composite ( 1 ) according to  claim 8  wherein the anti-tear powder ( 8 ) is associated with a mat of chopped glass fibers.  
     
     
         10 . A strengthening composite ( 1 ) according to  claim 3  wherein the strengthening threads ( 3  and  7 ) are contiguous in the first lap ( 2 ) and optionally in the third lap ( 6 ).  
     
     
         11 . A strengthening composite ( 1 ) according to  claim 3  wherein the strengthening threads are distributed over a first lap ( 2 ) of strengthening threads ( 3 ) that are mutually parallel and arranged in a sliver, and over a third lap ( 6 ) of strengthening threads ( 7 ) that are parallel to one another and to those of the first lap and are also arranged in a sliver, the slivers of the first lap being contiguous with those of the third lap so that the strengthening threads have a coverage of approximately 100%.  
     
     
         12 . A strengthening composite according to one of  claims 1  to  3  wherein the bonding threads ( 5 ) are distributed in groups of two, three or four.  
     
     
         13 . A strengthening composite according to  claim 1  or  12  wherein the spacing existing between each bonding thread ( 5 ) or group of bonding threads ( 5 ) has a pitch of between 1 and 10 cm.  
     
     
         14 . A strengthening composite ( 1 ) according to  claims 1  to  3  wherein the thermoplastic is selected from polypropylene, polyethylene, polyamide, polyethylene terephthalate, polyester, ethylene/vinyl acetate or mixtures thereof.  
     
     
         15 . A strengthening composite ( 1 ) according to one of  claims 1  to  3  wherein the strengthening threads ( 3  and  7 ), as well as the coated core of the bonding threads ( 5 ), are made of a material selected from glass, carbon, aramide and HP synthetics.  
     
     
         16 . A process for the manufacture of a strengthening composite ( 1 ) according to one of  claims 1  to  15  which comprises the following steps: 
 forming a first lap ( 2 ) of mutually parallel strengthening threads ( 3 ) and superimposing on this first lap ( 2 ) a second lap ( 4 ) of bonding threads ( 5 ) composed of a fibrous core coated with a thermoplastic and running transversely to the strengthening threads ( 3 ) of the first lap ( 2 ), being crossed without interlacing,  
 and bonding said laps ( 2  and  4 ) at their intersection by thermocompression.  
 
     
     
         17 . Use of a strengthening composite ( 1 ) according to one of  claims 1  to  15  in the manufacture of skis, wind blades or pultruded elements.