Method for the preparation of composite material in sandwich form

Abstract

The object of the invention can be a method of manufacturing a product in the form of a sandwich comprising a core and outer layers. The outer layers may be composed of composite material comprising a fiber-reinforced polymeric matrix. The method uses an insert of heat-resistant material, for example silicone. The object of this invention can be to provide a method of manufacturing a sandwich that dissociates the choice of material of the core of the sandwich from the choice of the material of the outer layers.

What is claimed is: 
     
         1 . A method of manufacturing a sandwich-shaped composite material product wherein the sandwich-shaped composite material product comprises two outer layers and a core, the outer layers having a matrix of fiber-reinforced polymeric material, the polymeric material having a melting point below the melting point of the material constituting the fibers;
 wherein the method being is characterized in that it uses an insert consisting of material having a melting point higher than the melting point of the polymeric material, on which the outer layers are consolidated; and   wherein this insert is subsequently replaced by the core of the sandwich-shaped composite material product to form an assembly, the assembly then undergoing a consolidation treatment for bonding the outer layers to the core,   wherein the method is further characterized in that it comprises the following steps:   juxtaposition, in a mold, of a fabric or knit made of reinforcing material, the insert, and a second fabric or knit made of reinforcing material;   injection of a resin of polymeric material under pressure and temperature;   removal of the insert and insertion of the core of the sandwich;   consolidation curing to adhere the outer layers to the core of the sandwich;   cooling of the product thus obtained.   
     
     
         2 . The method according to  claim 1 , characterized in that the insert is made of silicone. 
     
     
         3 . The method according to  claim 1 , characterized in that the reinforcing material is chosen from glass, carbon and aramid fibers. 
     
     
         4 . The method according to  claim 1 , characterized in that the polymeric material is of the thermoplastic type chosen from polycarbonate (PC), polyetherimide (PEI), polypropylene (PP), poly(ethylene terephthalate) (PET), and polyether ether ketone (PEEK). 
     
     
         5 . The method according to  claim 1 , characterized in that the polymeric material is of the thermosetting type, chosen from epoxy, cyanate ester, phenolic resins and polyester. 
     
     
         6 . The method according to  claim 1 , characterized in that the core of the sandwich-shaped composite material product consists of cellular honeycomb material. 
     
     
         7 . The method according to  claim 1 , characterized in that the thickness of the core is at least about 2 mm and not greater than about 50 mm. 
     
     
         8 . The method according to  claim 1 , characterized in that the thickness of each of the outer layers is at least about 0.2 mm and not greater than about 5 mm.