Abstract:
Process for manufacturing carbon fiber fabrics, in which a fabric of carbon fiber ( 1 ) is impregnated with a silicone, polyurethane or acrylic emulsion ( 4 ) which is then dried together with the fabric ( 1 ). The present invention also relates to a fabric manufactured with this process as well as a coating for motor vehicles comprising this fabric.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a 371 of PCT/IB2013/051113, filed Feb. 11, 2013, which claims the benefit of Italian Patent Application No. MI2012A000245, filed Feb. 20, 2012, the contents of each of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a process for manufacturing carbon fiber fabrics, in particular a flexible fabric that can be used to coat inner parts of motor vehicles. The present invention also relates to a coating for motor vehicles comprising this fabric. 
     BACKGROUND OF THE INVENTION 
     Known carbon fiber fabrics comprise a web of thin filaments of carbon fibers arranged perpendicularly to each other. These known fabrics are impregnated with polymeric resins and overlapped according to suitable directions. The resins are cured to obtain rigid materials with a high specific resistance, which are suitable for the production of structural parts or aesthetic parts. These materials, because of their stiffness characteristic, cannot be applied for example to the internal parts of motor vehicles, where flexible fabrics that can be sewn and folded are required. This also excludes the use of raw fabrics made of carbon fiber, which tend to unthread and are not able to keep unchanged the arrangement of the fibers once deformed. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is therefore to provide a fabric made of carbon fiber free from said drawbacks. Said object is achieved with a process, a fabric and a coating, whose main features are specified in the claims. 
     Thanks to its particular features, the fabric according to the present invention can be advantageously used for products and accessories of clothing or leather goods, in particular bags, as well as for other applications requiring a flexible fabric, such as for example coatings of seating and interior walls, in particular of motor vehicles. In fact, the fabric according to the present invention does not fray even when the fibers are stressed by the seams. Furthermore, even if deformed along two transversal axes of curvature, namely with concave or convex deformations, the fabric maintains a substantially perpendicular arrangement and a limited longitudinal sliding of the fibers, so as to avoid permanent deformations of its structure. 
     A particular protective layer is preferably applied to the fabric to improve the handling during the manufacture and/or to limit the flexibility of the fabric, as well as to make it resistant, waterproof, insulating, semi-transparent, non-transparent and/or opaque. 
     The fabric according to the present invention is pleasant to the touch and has a high resistance, superior to that of a raw fabric of carbon fiber, while retaining an extreme flexibility which allows also to create folds or hems on the same fabric without compromising the integrity. The fabric is also very elastic since its particular impregnation ensures a correct arrangement of the texture even after deformations. It is therefore possible to deform this fabric without compromising its texture and without causing unthreadings between the fibers. 
     According to an aspect of the invention, the particular silicone, polyurethane or acrylic emulsion also impregnates the most inner fibers of the fabric of carbon fiber, so as to obtain a fabric resistant to surface wear, but still extremely flexible. 
     At least one edge of the fabric in its final configuration is preferably folded and sewn on itself, so as to form a hem that prevents unthreading of the fibers of the most inner layers of the fabric. 
     Further advantages and characteristics of the fabric and of the process according to the present invention will become apparent to those skilled in the art from the following detailed and non-limiting description of an embodiment thereof with reference to the accompanying drawings in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a partial section of the fabric during a step of the process; 
         FIG. 2  shows the fabric of  FIG. 1  during a subsequent step of the process; 
         FIG. 3  shows the fabric of  FIG. 1  during a subsequent step of the process; and 
         FIG. 4  shows the fabric of  FIG. 1  during a further step of the process. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , it is seen that fabric  1  according to the present invention comprises at least a weave, in particular cloth, twill or satin weave, of yarns of carbon fiber having a linear density between 50 and 5000 g/km and comprising from 1000 to 60000 filaments, in particular from 3000 to 24000 filaments having a diameter comprised between 5 and 10 microns. The thickness of fabric  1  is comprised between 50 and 1000 microns. The basis weight of fabric  1  is comprised between 170 and 270 g/m 2 , in particular 210 and 220 g/m 2 . 
     In a first preliminary operating step, to ensure the regularity and a good aesthetic finish of the weave, fabric  1  is brushed and/or stretched at a temperature comprised between 30° and 200° and/or at a pressure comprised between 1 and 100 bar by means of two cylinders or two plates suitable to exert a variable pressure. 
     In a second preliminary operating step, at least one protective layer  2 , in particular comprising a film, a woven fabric or a nonwoven fabric, more particularly a polyurethane, polyamide or acrylic film, is applied onto one side of fabric  1 . The thickness of the protective layer  2  is comprised between 50 and 500 microns. The basis weight of the protective layer  2  is comprised between 20 and 40 g/m 2 , in particular 25 and 35 g/m 2 . The protective layer  2  is applied to fabric  1  by means of a lamination, in particular a hot calendering or pressing, in which fabric  1  and the protective layer  2  are laminated together at a temperature comprised between 30° and 200° and/or at a pressure comprised between 10 and 200 bar. During this operating step the surface of the protective layer  2  in contact with fabric  1  partially penetrates fabric  1 , so as to create an intermediate layer  3 , having a thickness comprised between 5% and 60% of the thickness of fabric  1 , in which the outer filaments of fabric  1  are integral with the protective layer  2 . 
     Referring to  FIG. 2 , it is seen that in a main operating step fabric  1  is impregnated with a silicone, polyurethane or acrylic emulsion  4  by means of sprayers  5 , or by smearing, immersion or with a “hot-melt” transfer procedure. Sprayers  5  are arranged on the opposite side of fabric  1  with respect to the protective layer  2 , namely fabric  1  is comprised between the protective layer  2  and sprayers  5 . Fabric  1  with the silicone, polyurethane or acrylic emulsion  4  is pressed through laminating rollers at a pressure exerted by the rollers comprised between 1 and 100 bar to penetrate the silicone, polyurethane or acrylic emulsion  4  into fabric  1  and remove the exceeding quantity. 
     In a subsequent step of the process the silicone, polyurethane or acrylic emulsion  4  in fabric  1  is dried, in particular through a heat treatment in an oven at a temperature comprised between 20° and 200° C., for a time comprised between 2 and 40 hours. At the end of this drying step fabric  1  is impregnated with a percentage of silicone, polyurethane or acrylic emulsion  4  comprised between 1% and 60% of the weight of fabric  1 . 
     Referring to  FIG. 3 , it is seen that in a subsequent optional step of the process, an aliphatic solution  6  is sprayed by means of the same sprayers  5  or of other sprayers onto fabric  1 , so as to apply a basis weight of the aliphatic solution  6  comprised between 48 and 90 g/m 2 , in particular 55 g/m 2 ±10% or 80 g/m 2 ±10%, after which the aliphatic solution  6  is dried. 
     The aliphatic solution  6  comprises polyacrylates, glycols and/or aliphatic polyurethane compounds, in particular opacifiers. The aliphatic solution  6  can also comprise silicon-oxygen chains. 
     Referring to  FIG. 4 , it is seen that in a further optional step of the process, an aqueous emulsion  7  of isocyanate and/or crosslinking polyurea substances is sprayed by means of the same spraying  5  or of other sprayers onto fabric  1 , after which this aqueous emulsion  7  is dried. 
     The basis weight of the fabric  1  at the end of the process is preferably comprised between 260 and 320 g/m 2 . 
     In an alternative embodiment, the silicone, polyurethane or acrylic emulsion  4  can be applied to fabric  1  in the described above manner before applying the protective layer  2 . 
     In a final operating step, at least one edge of fabric  1  impregnated with the silicone, polyurethane or acrylic emulsion  4  and joined to the protective layer  2 , if any, is folded and sewn on itself so as to form a hem. 
     Possible variants and/or additions may be made by those skilled in the art to the embodiment of the invention here described and illustrated remaining within the scope of the following claims. In particular, further embodiments of the invention may include the technical features of one of the following claims, with the addition of one or more technical features, taken individually or in any mutual combination, described in the text and/or illustrated in the drawings.