Abstract:
A window including a layer of optically clear structural polymer core and two layers of optically clear silicone applied to first and second sides of the core. A method is disclosed for manufacturing a window that comprises injection molding a layer of optically clear structural polymer and solidifying the structural polymer core. Optically clear silicone is then injected onto the entire surface of both of the first and second sides of the optically clear structural polymer core.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to polymer window articles and methods of manufacturing such window articles. 
       BACKGROUND 
       [0002]    Automakers are continuing to develop technologies directed to significantly reducing the weight of cars to improve fuel economy and reduce carbon admissions. Glass windows add significantly more weight per square meter of surface area than other types of exterior materials. Glass windows are significantly higher in density than polymer body panels and are considerably thicker than aluminum or steel exterior panels. 
         [0003]    Efforts to reduce the thickness of glass windows in vehicles result in increased sound transmission through glazing. Efforts to improve noise, vibration and harshness (NVH) performance by increasing the thickness of glass side panels have the disadvantage of increasing the weight of a vehicle. 
         [0004]    Regulatory requirements for vehicle glazing include standards for clarity and resisting scratches for more than 20 years. Glazing products must be able to withstand 20 years of exposure to ultraviolet light and abrasion from the elements and commercial car washes. Glazing products must also avoid the condition known as birefringence that is caused by the refraction of light in two slightly different directions to form two rays of light. One proposed solution to the above problems is to provide a molded polycarbonate glazing with a coating of UV inhibitors and scratch resistant materials or vacuum metalized surface. One disadvantage of polycarbonate glazing with coatings of UV inhibitors and scratch resistant compositions is that they are expensive and lack the durability to meet the long term standards for UV exposure and abrasion. 
         [0005]    This disclosure is directed to solving the above problems and other problems as summarized below. 
       SUMMARY 
       [0006]    According to one aspect of this disclosure, a window is provided that includes a layer of optically clear structural polymer, a first layer of optically clear silicone applied to a first side of the optically clear structural polymer, and a second layer of optically clear silicone applied to a second side of the optically clear structural polymer. 
         [0007]    The optically clear structural polymer may be polycarbonate, acrylic, or liquid crystal polymer. In one example, the liquid crystal polymer may be cyclo olefin co-polymer. 
         [0008]    The optically clear structural polymer may be between 2.0 and 6.0 mm thick, however, in some cases the thickness of the layer may be reduced to 1.5 mm. The first and second layers of optically clear silicone may be between 0.25 and 0.5 mm thick, however, in some cases the thickness of the layer may be up to 2 mm thick. The optically clear silicone may include a translucent colorant to create a desired aesthetic effect. 
         [0009]    According to one aspect of this disclosure, a method of manufacturing a window glass article is disclosed. The method includes an initial step of injection molding a layer of optically clear structural polymer. Optically clear silicone is then injection molded onto the entire surface of first and second sides of the layer of optically clear structural polymer. 
         [0010]    An alternative aspect of the method may further comprise injecting the optically clear structural polymer in a first mold, solidifying the optically clear structural polymer in the first mold to form a core, and transferring the core to a second mold. Silicone is injected as a liquid to coat first and second sides of the core. The silicone cures to solidify the silicone coatings on both sides of the core. The step of injecting liquid silicone may further comprising injecting a two part liquid polymer including silicone and a platinum catalyst, and holding the mold at a sufficient temperature and pressure to cure the two part liquid polymer. 
         [0011]    The method may further comprise injecting liquid silicone into the second mold to coat a first side of the core to form a core with a coating on a single side. As an alternative, the method may comprise transferring the core with the coating on the single side to a third mold and injecting silicone as a liquid to coat a second side of the core to form a core with a coating on a second side. 
         [0012]    According to another aspect of this disclosure a method is disclosed for manufacturing a window glass article in a rotational stack/cube molding machine. The method comprises injection molding a layer of optically clear structural polymer in a mold and then injection molding optically clear silicone onto first and second sides of the layer of optically clear structural polymer. The layer of the optically clear structural polymer is cured and solidified before injection molding the optically clear silicone. 
         [0013]    This disclosure is directed to solving the above problems and other problems as summarized below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of a vehicle shown in phantom with windows shown in solid lines. 
           [0015]      FIG. 2  is a fragmentary perspective view of a window partially in cross section including an optically clear structural polymer core coated with a layer of silicone on first and second sides. 
           [0016]      FIG. 3  is a diagrammatic partial cross-section view of an injection molding machine used to form the optically clear structural polymer core. 
           [0017]      FIG. 4  is a diagrammatic partial cross-section view of an injection molding machine forming a first layer of silicone bonded to a first side of the core. 
           [0018]      FIG. 5  is a diagrammatic partial cross-section view of an injection molding machine forming a second layer of silicone bonded to a second side of the core. 
           [0019]      FIG. 6  is a diagrammatic perspective view of a rotational stack/cube molding machine. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts. 
         [0021]    Referring to  FIG. 1 , a vehicle  10  is shown in phantom lines with the windows shown in solid lines. Static windows, such as stationary side windows and rear windows, are initially the type of window application to be considered for applying this disclosure and are generally identified by reference numeral  12 . Static windows  12  that do not include a wiper or do not rub against a seal as they are raised and lowered are most likely candidates for application of the disclosed technology. 
         [0022]    Referring to  FIG. 2 , the window  12  made according to one embodiment of this disclosure is shown to include an optically clear structural polymer core  16 . The optically clear structural polymer core  16  may be formed of polycarbonate, acrylic, or liquid crystal polymer. A first layer of silicone  18  is bonded to one side of the core  16 . A second layer of silicone  20  is bonded to an opposite side of the core  16 . The first and second layers of silicone  18  and  20  are formed by injecting a two-part liquid polymer including silicone and a platinum catalyst into a mold, as will be described in greater detail below with reference to  FIGS. 3-5 . 
         [0023]    Referring to  FIG. 3 , an injection molding machine is generally indicated by reference numeral  25 . Pellets of an optically clear structural polymer  26  are supplied to the injection molding machine  24  by a hopper  28 . The hopper  28  feeds the pellets  26  to the injection screw  30  of the injection molding machine  24 . The pellets  26  melt as they are subjected to heat and pressure and are injected into a core mold  32 , that may also be referred to herein as a first mold, to form the core  16 . The core  16  may be between 1.5 and 6.0 mm thick. 
         [0024]    Referring to  FIG. 4 , a two-part injection molding machine is generally indicated by reference numeral  34 . A first silicone mold  36  is provided with silicone  38  and a platinum catalyst  40 . The silicone  38  and platinum catalyst  40  are combined in a mixing head  42  and injected into the silicone mold  36 . The silicone/catalyst mixture is injected into the mold  36  to cover the entire first side  44  of the core  16  with the first layer of silicone  18 . 
         [0025]    Referring to  FIG. 5 , a two-part injection molding machine is generally indicated by reference numeral  34 . A second silicone mold  48  is provided with silicone  38  and a platinum catalyst  40 . The silicone  38  and platinum catalyst  40  are combined in a mixing head  42  and injected into the silicone mold  48 . The silicone/catalyst mixture is injected into the mold  48  to cover the entire second side  50  of the core  16  with the second layer of silicone  20 . The silicone layers  18  and  20  may be between 0.25 and 2.0 mm thick. 
         [0026]    The injection molding machines  25 ,  34  and  46  may be transfer mold injection molding machines, rotary transfer molding machines, or rotational stack/cube molding machines. Three transfer mold injection molding machines may be used to make the glazing article, or window, with a first injection molding machine  24  (shown in  FIG. 3 ) injecting the optically clear structural polymer into a mold to form a core or base. The article is transferred to a second transfer mold injection molding machine  34  (as shown in  FIG. 4 ) that injects the silicone thermoset material onto one side of the base. The article is then flipped over as the article is transferred to a third injection molding machine  46  (as shown in  FIG. 5 ) that injects the silicone thermoset material onto a second side of the base. 
         [0027]    Alternatively, a rotary transfer molding machine may be utilized that includes three injection molding stations. The core is molded at the first station by a first injection molding machine  24  (shown in  FIG. 3 ). The molded core is then transferred to a second station by a second transfer mold injection molding machine  34  (as shown in  FIG. 4 ) where silicone is molded on one side of the core. After molding silicone on one side of the core, the core with one side coated is flipped over and placed in a third station where a third injection molding machine  46  (as shown in  FIG. 5 ) applies a molded layer of silicone on the other side of the article. 
         [0028]    As shown in  FIG. 6 , another alternative is illustrated in which a rotational stack/cube molding machine  52  may be used that includes a plurality of stacked molds  54  on one side of a cube  56  that are injected on one side of the cube  54  at a first injection molding machine  58  to form the optically clear structural polymer core  16 . The cube  54  then rotates to a second injection molding machine  60  that injects the first layer of silicone  18  onto one side of the core  16 . A robot  62  may be used to flip over one (or a plurality of fixture mounted cores) core  16  with the first layer of silicone coating  38  on one side and place it in the third molding machine  64  to be coated with the second layer of silicone  20  on a second side. The finished window may then be unloaded by a robot  66  at a fourth station. 
         [0029]    The optically clear layers of silicone  18  or  20  may include a colorant to tint or color the windows  12  for aesthetics. 
         [0030]    The embodiments described above are specific examples that do not describe all possible forms of the disclosure. The features of the illustrated embodiments may be combined to form further embodiments of the disclosed concepts. The words used in the specification are words of description rather than limitation. The scope of the following claims is broader than the specifically disclosed embodiments and also includes modifications of the illustrated embodiments.