Process for manufacturing a steering wheel with thermoplastic composites

Abstract

A steering wheel or other component for motor vehicle interiors, is produced by pressure thermoforming an external layer of decorative material, together with an internal structural layer of support material that includes a matrix of thermoplastic material and a plurality of reinforcing fibers for the thermoplastic matrix. The matrix may be of polymer that impregnates the fabric or made of fabrics that are interwoven or mixed with the reinforcing fibers.

1 . A steering wheel comprising: 
 (a) a base structure; and    (b) at least one covering element applied onto said base structure, wherein said covering element comprises    (i) at least one internal structural layer comprising a thermoplastic material containing reinforcing fibers, the reinforcing fibers comprising about 10 to about 80% by weight of the internal structural layer, and    (ii) at least one external layer located on a side of the internal structural layer distal from said base structure and having an aesthetic function.    
     
     
         2 . The steering wheel according to  claim 1 , wherein said fibers are in the form of a woven fabric, the reinforcing fibers being at least about 12.0 mm long.  
     
     
         3 . The steering wheel according to  claim 1 , wherein said fibers are in the form of a non woven fabric, the reinforcing fibers being at least about 12.0 mm long.  
     
     
         4 . The steering wheel according to  claim 2 , wherein the amount of said reinforcing fibers in the internal structural layer is within the range of about 20 to about 60% by weight of the internal structural layer.  
     
     
         5 . The steering wheel according to  claim 3 , wherein the amount of said reinforcing fibers in the internal structural layer is within the range of about 20 to about 60% by weight of the internal structural layer.  
     
     
         6 . The steering wheel according to  claim 1 , wherein the weight of the internal structural layer is within the range of about 500 to about 3000 g/m 2 .  
     
     
         7 . The steering wheel according to  claim 1 , wherein the thermoplastic material of the internal structural layer is selected from the group consisting of: polyesters, polyacrylates, and polymethacrylates, homo and copolymers of polypropylene and polyolefines, homo and copolymers of polypropylene and polyolefins grafted with compounds having functional groups, and mixtures thereof.  
     
     
         8 . The steering wheel according to  claim 1 , wherein the fibers located in the thermoplastic material of the internal structural layer are selected from the group consisting of: fiber glass, carbon fiber, aluminum fiber, natural fibers such as cotton, sisal, jute, linen, hemp and similar; resin and plastic material fibers such as polyester, polyolefins, polyamides and polyaramides and a mix thereof, as long as the fibers have a melting temperature higher than the melting temperature of the thermoplastic material.  
     
     
         9 . The steering wheel according to  claim 7 , wherein the fibers located in the thermoplastic material of the internal structural layer are selected from the group consisting of: fiber glass, carbon fiber, aluminum fiber, natural fibers such as cotton, sisal, jute, linen, hemp and similar; resin and plastic material fibers such as polyester, polyolefins, polyamides and polyaramides and a mix thereof, as long as the fibers have a melting temperature higher than the melting temperature of the thermoplastic material.  
     
     
         10 . The steering wheel according to  claim 1 , wherein the at least one external layer located on a side of the internal structural layer distal from said base structure comprises wood.  
     
     
         11 . The steering wheel according to  claim 7 , wherein the at least one external layer located on a side of the internal structural layer distal from said base structure comprises wood.  
     
     
         12 . The steering wheel according to  claim 8 , wherein the at least one external layer located on a side of the internal structural layer distal from said base structure comprises wood.  
     
     
         13 . The steering wheel according to  claim 9 , wherein the at least one external layer located on a side of the internal structural layer distal from said base structure comprises wood.  
     
     
         14 . A steering wheel comprising: 
 (a) a base structure;    (b) at least one internal structural layer adhered directly to the base structure and comprising a thermoplastic material containing reinforcing fibers; and    (c) an external layer comprising wood located on a side of the internal structural layer distal from said base structure.    
     
     
         15 . A component for a motor vehicle interior comprising: 
 (a) a base structure; and    (b) at least one covering element applied onto said base structure, wherein said covering element comprises    (i) at least one internal structural layer comprising a thermoplastic material containing reinforcing fibers, the reinforcing fibers comprising about 10 to about 80% by weight of the internal structural layer, and    (ii) at least one external layer located on a side of the internal structural layer distal from said base structure and having an aesthetic function.    
     
     
         16 . A process for the production of a steering wheel having a base structure and at least one external covering subassembly attached to said base structure, comprising the steps of: 
 (A) producing a covering element subassembly by (a) placing an internal layer of structural material inside a mold, said internal layer of structural material including a thermoplastic material and reinforcing fibers located in said thermoplastic material; the reinforcing fibers comprising 10 to 80% by weight of the internal layer of structural material and the fibers are at least 12.0 mm long and in the form of a mat or in a woven or non-woven fabric impregnated with the thermoplastic material; (b) placing an external layer of a decorative material inside the mold exterior of and adjacent to the internal layer of structural material; (c) heating the mold to a temperature sufficient to shape said internal layer of reinforced thermoplastic material; and (d) bonding together and shaping said structural and decorative layers by pressure thermoforming such that melted thermoplastic material of the internal layer of structural material penetrates pores of the external decorative layer to bind the two layers together in the absence of thermoset resin adhesives to provide the covering element; and thereafter    (B) attaching the covering element produced in step (A) to the base structure.    
     
     
         17 . The process according to  claim 16 , wherein said layer of structural material is heated before placing it in a heated mold.  
     
     
         18 . The process according to  claim 16 , wherein said mold is heated to a temperature within the range of Tf to (Tf+20° C.) where Tf is the melting temperature of said thermoplastic material.  
     
     
         19 . The process according to  claim 16 , wherein said mold is cooled after having shaped and bound together said layers.  
     
     
         20 . The process according to  claim 16 , wherein step (A) is repeated to produce two covering elements shaped as half shells and said half shells are joined together around said base structure by welding.  
     
     
         21 . (canceled)  
     
     
         22 . (canceled)