Patent Publication Number: US-2010109191-A1

Title: Method for making multi-layered molded articles

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part application of U.S. Ser. No. 12/168, 236, filed Jul. 7, 2008 the contents of which are hereby incorporated by reference. The parent application Ser. No. 12/168, 236 in turn claims the benefit of priority under 35 USC 119 from Chinese Patent Application 200710203343.8, filed on Dec. 21, 2007. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to a method for making multi-layer molded articles. 
     2. Description of Related Art 
     Molded articles, such as molded shells, are widely used in many technological fields. One example is a molded shell used with a portable electronic device (e.g., a mobile phone) for protecting internal electronic components. Another example is a molded shell used with furniture (e.g., a mini sofa) to provide decoration. 
     The molded shells may include a plastic substrate having some kind of decorative and/or protective (hereinafter “second”) layer formed thereon. The molded shell may be made using an insert molding process. The second layer is placed in the mold cavity and then bonds to the molten plastic injected into the mold for forming the substrate. 
     Various difficulties may be faced when manufacturing this multi-layer molded article. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the method for making the multi-layered molded article can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the method for making the multi-layered molded article. Moreover, in the drawings like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  shows an exploded, schematic view of an exemplary embodiment of the present multi-layered molded article; 
         FIG. 2  shows a schematic view of the soft layer positioned between a female mold portion and a male mold portion; 
         FIG. 3  shows a schematic view when a male mold portion is matingly engaged with the female mold portion of  FIG. 2 ; 
         FIG. 4  shows a schematic view of the multi-layered molded article after molten material is injected into a mold cavity; 
         FIG. 5  shows a schematic view of a semi-manufactured article being cut by a punching machine; and 
         FIG. 6  is a cross-sectional view of the punch head. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Referring to  FIG. 1 , an exemplary embodiment of a multi-layered molded article  10  is shown. Article 10 includes a soft layer  12  and a substrate  14  moldingly bonded to the soft layer  12 . 
     The soft layer  12  can be made of a material that is soft relative to the substrate  14 . Exemplary soft materials include leather (natural and artificial), all types of fabrics, woven clothes, textiles, and nylon. The soft layer has first and second surfaces. One surface of the soft layer gives the final molded article its tactility and aesthetics. The other surface of the soft layer  12  acts as a bonding surface  122  for bonding the soft layer  12  to the substrate  14 . When the soft layer  12  is natural leather, typically, both the first and second surfaces are the natural leather. When the soft layer is an artificial leather, typically the first surface will be the artificial leather and the second surface will be a fabric base covering the artificial leather. The fabric base will be used as the bonding surface  122 . 
     The bonding surface  122  should have a rough or coarse surface, formed by, for example, a plurality of tiny pores or projections (schematically shown). For some soft materials, the pores and projections of the bonding surface  122  may be a natural property of the material. For other soft materials, the pores and projections may be formed by grinding or sandblasting the bonding surface  122 . The tiny pores and projections of the bonding surface  122  interlock with the molten material used to make substrate  14 , thereby increasing the bonding of the soft layer  12  to the substrate  14 . 
     The substrate  14  can be formed by injection molding a moldable material. The moldable material can be any of plastic, rubber, and silicone. The plastic material can be any of polyvinylchloride resin (PVC), polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), polyimide (PI), liquid crystal polymer (LCP), polyetherimide (PEI), polyphenylene sulfide (PPS), polystyrene (PS), polypropylene (PP). In particular, ABS and PC exhibit good adhesion to many softer materials. 
       FIGS. 2-5  depict the steps of an exemplary method for preparing an exemplary multi-layered molded article  10 . The soft layer  12 , in the form of a soft material  22  is provided. The soft material  22  includes a first surface  222  and a second surface  224 . The second surface  224  functions as the bonding surface  122  as previously described. In this exemplary embodiment, the soft material  22  is made of natural leather or artificial leather. The natural leather and artificial leather require the ability to endure the temperatures of the molten material which will be injected into the mold and are typically on the order of 300° C. temperature. The surface area of the soft material  22  is larger than the surface area the surface portion of the multi-layered molded article  10  to which a soft layer  12  is applied. 
     Referring to  FIG. 2 , an injection mold is provided. The injection mold includes a female mold portion  32  and a male mold portion  34 , for mating with the female mold portion  32 . The female mold portion  32  defines a recess  322 . A protrusion  342  extends from the male portion  34 . A runner  3422  is defined in a central area of the male mold portion  34 . When the soft material  22  is positioned over/on the female mold portion  32 , the soft material  22  includes a perimeter edge portion  25  freely placed on the female mold portion  32 . The first surface  222  of the soft material  22  faces the male mold portion  34 . 
     Referring to  FIG. 3 , when the female mold portion  32  mates with the male mold portion  34 , a mold cavity  36  is defined between the female mold portion  32  and the male mold portion  34 . However, before the mating, as the male mold portion  34  is moved towards the mating position with the female mold portion  32 , protrusion  342  of the male mold portion comes into contact with, and begins pushing, the soft material  22  into the mold cavity. The deflection of the soft material  22  due to its being pushed by the protrusion  342  causes the perimeter edge portions  25  to be pulled toward the mold cavity  36 . Since the soft material  22  is not fixed to the female mold portion  32 , and not yet clamped between the male and female mold portions, the soft material  22  may be deflected by the incoming male mold portion  34  but not substantially deformed or stretched in a way that would degrade from the final product. When the female mold portion  32  and the male mold portion  34  are finally mated, the perimeter edge portion  25  is clamped between the female mold portion  32  and the male mold portion  34 . Two sloping portions  26 , connected to the perimeter edge portion  25 , are formed in the mold cavity  36 . The sloping portions  26  do not contact the protrusion  342  of the male mold portion  34  or the sidewalls of the recess  322  of the female mold portion  32 . 
     Referring to  FIG. 4 , after mating of the mold portions and partial deflection of the soft layer  12 , molten material is injected into the mold cavity  36  through the runner  3422 . The molten material pushes the soft material  22  away from, and out of contact with the protrusion  342  and further toward the female mold portion  32  and further into the mold cavity  36 . As the molten material continues filling the mold cavity  36 , the air and reaction gases in the mold cavity  36  flow toward the space between the sloping portions  26  and the protrusion  342  and the space between the sloping portions  26  and the sidewall of the recess  322 . The air and reaction gases are then vented from the mold cavity by clearance between the male mold portion  34  and the female mold portion  32 . The release of air and reaction gases during formation of the molded article  12  allows for improved stiffness in the final product. Additionally, because molten material flows from the area of runner  3422  to areas adjacent the perimeter edges of the mold apparatus, wrinkles in the soft layer  12  may be pushed toward the sloping portion  26  by the incoming molten material to decrease wrinkles in the bonding portion of the soft material  22  and achieve a better appearance. 
     When the soft material  22  is made of natural leather, the injected molten material will locally melt portions of the inside leather surface of the natural leather to promote bonding between the molten material and the inside surface of the soft material. When the soft material  22  is made of artificial leather, the injected molten material will locally melt the fabric base of the artificial leather to promote bonding between the molten material and the inside surface of the soft material. 
     The molten material is cooled and the soft material  22  integrally forms with the substrate  14  to form a semi-manufactured article  20 . After the mold cavity  36  is filled, the substrate  24  is formed and the soft material  22  in the mold cavity  36  is pushed into contact with the female mold portion  32 . After cooling, the male mold portion  34  is moved away from the female mold portion  32 , and the semi-manufactured article  20  is taken out from the injection mold. 
     Referring to  FIG. 5 , the semi-manufactured article  20  has an outline  202  formed by the edge separating the angled portion and the perimeter edge portion. The portion of the semi-manufactured article  20  outside the outline  202  needs to be removed. 
     A punching machine (only a portion of which is shown) is provided and configured for performing a punching process that removes excess portions of the semi-manufactured article  20 . The punching machine includes a die cutter  90  and a positioning tool  80 . The position tool  80  includes a base  82  and a platform  84 . The platform  84  is positioning on the base  82 . Referring to  FIG. 6 , the die cutter  90  includes a metal frame  92  and a knife edge  94  formed on four sides. Each knife edge  94  is wedge-shape and has a predetermined configuration according to the pattern of the desired outline  202 . The semi-manufactured article  20  is then fixed on the platform  84  of the positioning tool  80  of the punching machine. The metal frame  92  is heated, and the knife edges  94  are directed onto the outline  202  of the semi-manufactured article  20 . The semi-manufactured article  20  is cut to a predetermined size and shape by the knife edges  94  of the punching machine, thereby forming the multi-layered molded article  10  with the soft layer  12 . The multi-layered molded article  10  achieved by using the punching process may have a smooth brim and the soft layer  12  completely covering a surface of the substrate  14 . 
     The deformation of the soft material  22  by the male mold portion  34  is small since the soft material  22  is not fixed to the female mold portion  32 . Thus, the mold cavity  36  may have a high depth. 
     It should be also understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.