Abstract:
A process for manufacturing a urethane foam pad comprising the steps of: providing a urethane resin and a filler agent; mixing a predetermined amount of the filler agent with the urethane resin to create a urethane mixture within a mold container; drawing a vacuum on the urethane mixture; allowing the urethane mixture to expand and gel for a predetermined amount of time to form an expanded urethane foam pad; releasing the vacuum on the urethane mixture; and removing the expanded urethane foam pad from the mold container.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 62/331,518, filed on May 4, 2016. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention relates to a process to manufacture ultra high filled urethane foam. More particularly, the invention relates to manufacturing a urethane foam pad with improved thermal conductivity for increasing the heat transfer through the foam pad. 
       2. Description of Related Art 
       [0003]    Automotive vehicles include one or more seat assemblies having a seat cushion and a seat back for supporting a passenger or occupant above a vehicle floor. The seat assembly is commonly mounted to the vehicle floor by a riser assembly. The seat back is typically operatively coupled to the seat cushion by a recliner assembly for providing selective pivotal adjustment of the seat back relative to the seat cushion. Each of the seat cushion and seat back commonly comprise a base foam pad supported by a rigid frame structure and encased in a textile trim cover of cloth, leather, and/or vinyl. The base foam pad provides the firm support and durability to the seat cushion and seat back. A trim foam pad, commonly referred to as a plus pad, is also frequently disposed between the base foam pad and the trim cover to provide a softer surface for seat occupant comfort and to improve the appearance of the seat. 
         [0004]    It is commonly known to provide seat assemblies with heating and cooling mechanisms for selectively heating and cooling the surface of the seat for seat occupant comfort. These known heating and cooling mechanisms are typically independent mechanisms. For example, it is common to provide an electric wire heating pad between the foam pad and trim cover of the seat cushion or seat back which is electrically actuated by the power from the vehicle battery to electrically charge the heating pad and provide heat to the surface of the seat cushion or seat back. It is also known to provide fans and air ducts to force cool air through the foam pad and trim cover and provide cool air to the surface of the seat cushion or seat back. It is also known to provide fans and ducts to draw warm, moist air away from the seating surface to provide a gradual cooling effect. 
         [0005]    However, current heating and cooling mechanisms require a fair amount of time and power to generate sufficient heat or cool air to affect the temperature of the seat assembly and the desired comfort for the seat occupant. 
         [0006]    Additionally, the base foam pad and the trim plus pad are typically composed of cellular urethane foam having a very low thermal conductivity, and as such, heat can build up between the seat occupant and padding materials. The base foam pad and trim plus pad also act as an insulator rather than transferring the heat or cold to the surface of the seat assembly, and thus the power levels of the heating and cooling mechanisms have to be substantial to overcome the insulating properties and effects of the foam pads. 
         [0007]    It is desirable, therefore, to provide a thermally conductive foam pad for transferring and dispersing the heat or cold to and from the surface of the seat assembly. It is also desirable to provide a process for manufacturing ultra high filled urethane foam with filler materials to improve the thermal conductivity of the foam. 
       SUMMARY OF THE INVENTION 
       [0008]    A process for manufacturing a urethane foam pad is provided comprising the steps of: providing a urethane resin and a filler agent; mixing a predetermined amount of the filler agent with the urethane resin to create a urethane mixture within a mold container; drawing a vacuum on the urethane mixture; allowing the urethane mixture to expand and gel for a predetermined amount of time to form an expanded urethane foam pad; releasing the vacuum on the urethane mixture; and removing the expanded urethane foam pad from the mold container. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0010]      FIG. 1  is a perspective view of a container of urethane resin and a container of filler agent; 
           [0011]      FIG. 2  is a perspective view of a mold container of the filler agent added to the urethane resin; 
           [0012]      FIG. 3  is a perspective view of the mold container of a urethane mixture of the resin and filler agent; 
           [0013]      FIG. 4  is a perspective view of the mold container on a vibration table; 
           [0014]      FIG. 5  is a perspective view of the mold container placed in a vacuum chamber; 
           [0015]      FIG. 6  is perspective view of the urethane mixture in the mold container prior to vacuum draw and foam expansion; 
           [0016]      FIG. 7  is a perspective view of the urethane mixture in the mold container after vacuum draw and foam expansion; and 
           [0017]      FIG. 8  is a perspective view of a plurality of expanded foam plus pads formed by the urethane foam process. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0018]    In the automotive seating industry, as one example of use, a seat assembly generally includes a horizontal seat cushion and a generally upright seat back for supporting a seat occupant within the vehicle as is commonly known in the art. Each of the seat cushion and seat back commonly include a molded resilient cellular foam base pad encased in a trim cover, commonly of cloth, vinyl, or leather. The base pad provides the resilient support to the seat occupant. A trim pad, commonly referred to as a plus pad, is typically positioned between the base pad and the trim cover to provide softer surface comfort to the seat occupant and to improve the appearance of the seat. However, both the base pad and the trim plus pad currently have a very low thermal conductivity of approximately 0.043 W/m-K, and as such, heat can build up between the seat occupant and the trim plus pad. It is also commonly known to provide a heating or cooling mechanism, such as an electric heating pad, in the seat assembly for providing occupant comfort. However, the trim plus pad acts as an insulator, and therefore, the desired heating and cooling effects take considerable time to be felt by the occupant. Further, the power levels of the heating and cooling mechanisms have to be substantial to overcome the insulating effects of the trim plus pad. 
         [0019]    The trim plus pad is typically manufactured of urethane foam which includes millions of air pockets that permeate the foam and make it naturally insulating. It is currently known to add filler materials to the urethane foam using a variety of filling agents to enhance the thermal properties of the foam. For example, foams have been created in the bedding industry with enhanced thermal properties by using filling agents including graphite, aluminum, aluminum oxide, silver, copper, as well as other conductive fibers. However, because of the chemistry of urethane foam, the amount of filler is limited. That is, at high loading or filling levels above 40% by weight, the foam becomes unstable and collapses during the foaming process. As a result, these modest filling levels offer only modest improvement in the thermal properties of the foam. 
         [0020]    Traditional urethane foam is created through a process of two separate chemical reactions as is commonly known in the art. The foaming reaction occurs when an isocyanate group reacts with water to create a froth, and one of the products is carbon dioxide gas (CO 2 ). As the CO 2  is produced, the urethane precursors expand and physically grow in the mold or container they are being formed in. Once the expansion in the mold is largely complete, the gelling reaction takes over with isocyanate groups and —OH group, from a common group of chemicals called polyols. The gelling reaction is what actually makes the polyurethane, and creates a stable flexible foam material. However, during the foaming reaction, the urethane precursors are very unstable, and many things can make the froth collapse. For example, vibrations, speed of the frothing, contaminates, and most importantly, the weight of filling agents, can all make the froth collapse in the mold. In fact, filling agents over 40% of the foam mixture by weight, can often collapse the delicate froth simply due to gravity thereby limiting the amount of filler a urethane foam can hold. 
         [0021]    Referring to the Figures, a foam pad and process of manufacturing an ultra high filled urethane foam pad is shown according to one embodiment of the invention. Referring to  FIG. 1 , a pair of mixing containers are shown at  10  and  12 . One of the mixing containers  10  includes a filler material  14 , or filling agent, which may consist of aluminum, copper, graphite, graphene, aluminum oxide, silver or other conductive fibers. The other one of the mixing containers  12  includes elastomeric urethane as the preferred resin  16  which is normally free of water such that there is no foaming reaction and only a gelling reaction to create a solid elastomeric urethane. More specifically, the resin is a mixture of an isocyanate component with a resin/polyol component. Referring to  FIGS. 2 and 3 , the process includes the step of adding the filling agent  14  from container  10  to the resin  16  in container  12  and then thoroughly mixing the filling agent  14  with the resin  16 . The combination of filing agent  14  and resin  16  creates an ultra high filled urethane mixture  18 . It should be appreciated that the container  12  may be a foam mold of any desired shape and size without departing from the scope of the invention. The next step in the process includes placing the container  12  of the ultra high filled urethane mixture  18  comprised of the filling agent  14  and resin  16  onto a vibration table  20  as shown in  FIG. 4  and vibrating the container  12  to remove or reduce any large entrapped bubbles in the mixture  18 . 
         [0022]    Referring to  FIG. 5 , the process further includes placing the container  12  and mixture  18  into a vacuum chamber  22  and sealing the chamber  22  with a vacuum seal  24 . A vacuum pump  26  is then actuated to draw a vacuum on the chamber  22  at a predetermined and desired vacuum rate and intensity to allow the mixture  18  to froth and foam up in the container  12 . The vacuum pump is deactivated and to stop the vacuum draw when the desired foam expansion is achieved allowing the gelling reaction to be completed over a predetermined and desired amount of time. The final step in the process includes releasing the vacuum, opening the vacuum seal  24  and chamber  22 , and removing the container  12  with the foamed mixture  18  from the container  12 .  FIG. 6  shows the mixture  18  prior to the vacuum draw and foam expansion and  FIG. 7  shows the foam plus pad  30  after the foam expansion. 
         [0023]    Referring to  FIG. 8 , the thermally enhanced foam plus pad  30  may be cut to various shapes and desired thicknesses for use between the base pad and the trim cover of a seat assembly. The thermally enhanced foam plus pad  30  has an increased thermal conductivity of approximately 0.365 watts/mK, resulting in an 8× improvement over the traditional foam plus pad. By foaming in the vacuum environment, a stable foam with filling or loading levels of 75% or more are achievable, thereby forming urethane foams with properties of the filler agents to greatly improve the thermal conductivity of the foam plus pad  30 . 
         [0024]    The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described.