Abstract:
A method of making a cosmetic cover includes coating the interior of a mold with successive layers of one or more curable materials. An outer such layer is provided with means to create a non-homogeneous color effect in that layer, and at least an inner such layer is provided with means to create a background color, for the said outer layer, in the said inner layer.

Description:
TECHNICAL FIELD 
     The present invention relates to a method of making a cosmetic cover comprising coating the interior of a mould with successive layers of one or more curable materials. 
     BACKGROUND ART 
     Such a method has already been proposed in which each layer contains different pigments at different loadings to produce the desired overall colouring for the cover. 
     One disadvantage of a cover made by such a method is that the colouring is not very realistic. 
     It is an aim of the present invention to obviate this disadvantage. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a method as set out in the opening paragraph of the present specification, in which at least an outer such layer is provided with means to create a non-homogeneous colour effect in that layer, and at least an inner such layer is provided with means to create a background colour, for the said outer layer, in the said inner layer. 
     It will be appreciated here that the outermost layer of the cover is the layer which is first-formed in the moulding. 
     The total number of layers with which the interior of the mould is coated may be three or more. 
     The said one or more curable materials may comprise a liquid monomer. Alternatively, or in addition, the said one or more materials may comprise a semi-liquid monomer. 
     The said means to create a non-homogeneous colour effect may be in the form of coloured lengths of fibres. Alternatively, they may comprise a variation in the thixotropy of the said one or more curable materials. Alternatively, the means to create a non-homogeneous colour effect may comprise dye-containing capsules having a form which will allow the passage of dye material within them into the layer during or after the curing process. Thus, the passing of the dye into the layer from the capsules may be caused by the curing process itself, or alternatively for example upon the exposure of the layer to sunlight. 
     Alternatively, such dyes could be introduced as solids, such as powders or crystals, or liquids directly into the layer. 
     The dyes used might be sensitive to light, such as for example polychromatic dyes. 
     The present invention extends to a method of making a coloured layer of material comprising introducing a dyestuff in a curable or cured layer to provide a non-homogeneous coloured layer. 
     The present invention also extends to a method of making a coloured layer of material comprising varying the thixotropy of one or more curable materials from which such a layer is made, thereby to produce a non-homogeneous colour effect in the layer. 
     An example of a method of making a cosmetic cover in accordance with the present invention is illustrated in the accompanying diagrammatic drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an elevational perspective side view of apparatus for effecting the method; and 
     FIG. 2 shows an axial sectional view of a product of that method. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows an elongate mould  10  with a closed generally hemispherical base  12  held on an axis of a rotary drum  14  by means of foam packing  16  between the walls of the drum  14  and the mould  10 . The mould  10  has an outer open end  18  projecting beyond front end faces  20  of the foam packing  16 . To assist in the insertion of the mould  10  in the foam packing  16  within the drum  14 , the drum is in two halves, which are hinged together and which are held in a closed position by means of toggle clamps  22 . 
     Around the periphery of the drum  14  at its forward end, there is a toothed drive ring  24  engaged by a toothed wheel  26  of a drive roller  28 . The drum  14  is also supported by an idle roller  30  spaced apart horizontally from the drive roller  28 . 
     A probe  32  extends axially within the mould  10  to feed warm air into the interior thereof, which enters the probe  32  from a tube  34  connected to a source of warm air (not shown). 
     When the apparatus is used, the mould  10  outside the drum  14  is filled with a curable silicone fluid. The mould  10  is then emptied, the viscous nature of the silicone fluid being such as to leave a coating on the interior of the mould  10 . 
     The latter is then placed in the foam packing  16  of the drum  14  as shown in FIG.  1  and the drum  14  is rotated by the drive roller  28  about the axis of the drum, as shown by the arrow a in FIG.  1 . Simultaneously, hot air is fed through the hose  34  into the probe  32 , from which it exits into the interior of the mould  10 . Eventually, hot air along with the solvent vapour of the silicone fluid escapes through the open end  18  of the mould  10 . During this process strongly coloured short-length fibres are fed into the interior of the mould  10 . This may be accomplished through the same probe  32 . It produces a non-homogeneous colour effect in the layer thus formed. Eventually, the silicone gels to form a first layer on the interior of the mould  10 . 
     The mould  10  is now removed from the drum  14 , and is once again filled with silicone fluid, which again is then tipped out from the mould  10 . This further amount of fluid silicone is dyed uniformly to provide a background colour for the layer already created. 
     The second layer of silicone is gelled in the same way as the first, by placing the mould in the drum  14 , rotating the latter and simultaneously passing hot air into the interior of the drum  14 . The resulting cured silicone layers are then removed from the mould  10 . They constitute a cover as shown in FIG. 2 having an outer layer  40  and an inner layer  42 . The outer layer has a non-homogeneous colour effect created by the presence of the non-uniformly distributed fibres  44 . The cover  36  also has an inner layer  42  providing a background colour for the outer layer  40 . This cover  36  has a realistic skin-like appearance and is therefore particularly suitable for a prosthesis. 
     In an alternative method of creating such a cover, which will not now be described with reference to any particular Figures in the drawings, a mould like the mould  10  is heated in an oven. It is then removed from the oven and vinyl chloride monomer is poured into the mould. The mould is then emptied and the mould with a layer of the monomer on its interior, is replaced in the oven. 
     Either just before or during the heating of this layer of monomer, brightly coloured short-length fibres are scattered on to this layer so as to produce a non-homogeneous colour effect in that layer. 
     Once the layer of monomer has polymerised to become polyvinyl chloride, the mould is removed from the oven and a further amount of vinyl chloride monomer is poured into the mould to fill the latter. The liquid monomer is again tipped out so that the second layer of the monomer is left on the polymerised layer. This second layer is uniformly covered with a dye to create a background cover for the first layer. The mould is then re-inserted into the oven and the second layer is polymerised. Once the curing process is complete, the cover is removed from the mould and, although it is made of a different substance, looks substantially the same as the cover shown in FIG.  2 . 
     Numerous variations and modifications to the illustrated method may occur to the reader without taking the resulting method outside the scope of the present invention. For example, there may be three or more layers altogether in the finished cover, providing there is at least one outer layer having a non-homogeneous colour effect, and at least one inner layer providing a background colour. Further printing may be applied on the exterior of the cover  36  shown in FIG. 2 to enhance the overall colouring effect even further. Alternatively, further colouring could be injected into the surface of the cover  36  to this end. 
     The fluid silicone or vinyl chloride monomer and resulting cured material in the layer  40  itself has no pigment loading, or a very low pigment loading, the final colouring effect in the layer  40  being effected substantially solely by the strongly coloured short fibres  44  in these examples. 
     Materials other than polyvinyl chloride may be used to create the layers. Silicone or polyurethane could be used. 
     Curing of the monomer may be by chemical means rather than by heating. 
     The mould  10  may be of a different shape, and may comprise more than one part.