Abstract:
A vehicular headliner comprising a molded foam element is described. The headliner comprises energy management capabilities to improve vehicle occupant safety. The headliner comprises an A-surface disposed to face an interior of a vehicle and a B-surface substantially opposed to the A-surface. The headliner includes a molded foam element having a substantially uniform density and an indentation force deflection at 25% deflection in the range of from about 150 pounds to about 4000 pounds when measured pursuant to ASTM 3574-B 1 . The foam element comprises a peripheral portion, a non-peripheral portion and an intermediate portion disposed therebetween, the intermediate portion having a greater cross-sectional thickness than at least one of the peripheral portion and the non-peripheral portion. A process for producing the headliner is also described. A mold for producing the headliner is also disclosed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    In one of aspects the present invention relates to a headliner, more particularly a vehicular headliner. In another of its aspects, the present invention relates to process for the production of a headliner. In yet another of its aspects, the present invention relates to a mold useful for the production of a foam element, particularly a headliner, more particularly a vehicular headliner.  
           [0003]    2. Description of the Prior Art  
           [0004]    Vehicular headliners are generally known in the art. More particularly automotive headliners are generally known in the art.  
           [0005]    As is known such automotive headliners are used to line the roof of the automobile. Conventionally, an automotive headliner is a laminate structure comprising, for example, a foam or other padded element having a cover material secured thereto. The cover material comprises a finished outer surface that faces the interior of the automobile and this the cover material is disposed adjacent or is comprised in the so-called A-surface of the headliner. The surface of the headliner adjacent the A-surface is the so-called B-surface. The B-surface of the headliner may or may not comprise a cover material.  
           [0006]    Conventionally, foamed automotive headliners have made produced from isocyanate-based foams such as polyurethane foams.  
           [0007]    When producing automotive headliners from polyurethane foams, it is conventional to utilize the so-called free-rise or slab polyurethane foams.  
           [0008]    In a typical slab polyurethane foam production plant, the resultant foam is usually produced by dispensing a foamable composition into a trough having an open top (also known as a tunnel) and a conveyor bottom to move the composition away from the mixhead as the foam rises. Low pressure mixing is typically used and involves metering the components for foam production into a mixhead equipped with a stirrer (or other suitable agitation means) at a pressure generally less than 500 psi (usually 200-350 psi). The components are mixed in the mixhead and the foamable composition is expanded to produce polyurethane foam. As is known in the art, low pressure mixing is conventionally used to produce slabstock foam. It is known to vary the properties of the resulting foam by varying the nature and/or amount of one or more of the metered components.  
           [0009]    Commercial slabstock polyurethane foam plants produce foam “buns” having dimensions such as 4 feet (height)×6 feet (width)×100 feet (length). Each bun is then cut into a plurality shorter length (e.g., 5 feet) buns, depending on the specifications of the particular automotive headliner being produced. The shorter length bun is then sliced into sheets of appropriate thickness (e.g., ½ to 1½ inches). Each sheet is then covered, trimmed and secured in the automobile. It is also known in the art to subject each sheet to further processing steps such as thermoforming so to confer to the planar sheet a slightly contoured appearance which more closely assumes the shape of the roof of the automobile.  
           [0010]    Thus, slabstock polyurethane foam conventionally used in the production of automotive headliners is known as a foam (e.g., a resilient foam) having at least one uncontoured surface (i.e., the foam is a “free-rise” foam).  
           [0011]    Regardless of the precise mode of production, an automotive headliner produced from slabstock foam suffers from the disadvantage of requiring many productions steps and resulting the in the production of relatively large amounts of scrap foam which can be difficult to discard.  
           [0012]    U.S. Pat. Nos. 5,683,796 and 5,721,038 [both to Kornylo et al. (Kornylo)] teach a vehicular headliner made from molded polyurethane foam. The headliner taught by Kornylo purportedly comprises a substantially constant density while having central sections with a greater cross-sectional thickness than peripheral portions. The central sections must be relatively thick such that the headliner possesses acceptable sound absorbing properties while the peripheral portions must be relatively thin so as to facilitate securing of the headliner to the roof of the automobile.  
           [0013]    Notwithstanding, the teachings of Kornylo there is significant room for improvement. For example, Komylo does not teach or suggest a vehicular headliner which can be regarded as an energy management device. While Komylo does teach the use of a reinforcing layer at the A-surface of the headliner this does not confer energy management properties to the headliner. Specifically, as is known in the art, the use of a reinforcing layer at the impact surface of the foam renders the impact surface harder and does note necessarily confer energy dissipation properties to the foam body.  
           [0014]    Further, the process taught by Kornylo is disadvantageous since it is a requirement to spray the entire surface of the mold with varying amounts of foamable composition depending on the thickness of the finished part in the area being sprayed. Specifically, Komylo teaches that, during the process, foamable material is sprayed such that a greater amount of foamable material per unit area will generally be applied to central portions of the part relative to the amount of foamable material per unit area applied to peripheral portions of the part, the foamable material being applied to the different areas in amounts generally commensurate with a desired thickness of the headliner assembly at the different areas. Apparently, this results in apart having a substantially uniform density. The disadvantages accruing from this approach include the requirement to spray the entire surface of the mold (i.e., this has a deleterious affect on the overall efficiency of the assembly line) and the spraying mechanism is relatively-complicated since it must dispense varying amounts of foamable material depending on the area of the part being sprayed.  
           [0015]    There is a developing need for headliners which possess energy management properties. Ideally, the energy management properties would obviate or mitigate injury to an occupant of the vehicle upon impact of the headliner by the occupant (i.e., compared to conventional headliners having little or energy management properties).  
           [0016]    It would be preferable if a vehicular headliner having energy management properties could be manufactured in a moulding process. It would be even more preferable if the moulding process had desirable combination of efficiency and simplicity compared to the difficulties associated with the Kornylo process described above.  
         SUMMARY OF THE INVENTION  
         [0017]    It is an object of the present invention to provide a novel vehicular headliner which obviates or mitigates at least one of the above-mentioned disadvantages of the prior  
           [0018]    It is another object of the present invention to provide a novel process for producing a vehicular headliner.  
           [0019]    It is another object of the present invention to provide a novel mold for producing a vehicular headliner.  
           [0020]    Accordingly, in one of its aspects, the present invention relates to a headliner comprising an A-surface disposed to face an interior of a vehicle and a B-surface substantially opposed to the A-surface, the headliner comprising a molded foam element having a substantially uniform density and an indentation force deflection at 25% deflection in the range of from about 150 pounds to about 4000 pounds when measured pursuant to ASTM 3574-B 1 , the foam element comprising a peripheral portion, anon-peripheral portion and an intermediate portion disposed therebetween, the intermediate portion having a greater cross-sectional thickness than at least one of the peripheral portion and the non-peripheral portion.  
           [0021]    In another of its aspects, the present invention relates to a process for producing a headliner in a mold comprising a first mold half and a second mold half engagable to define a mold cavity, the process comprising the steps of:  
           [0022]    (i) placing a first cover material in the first mold half;  
           [0023]    (ii) applying a-vacuum to the first mold half such that the cover material substantially assumes a shape of the first mold half;  
           [0024]    (iii) dispensing a liquid foamable polymeric composition on a portion of a surface of one of the first mold half and the second mold half;  
           [0025]    (iv) closing the first mold half and the second mold half;  
           [0026]    (v) expanding the liquid foamable polymeric composition to fill substantially the mold cavity to produce the headliner.  
           [0027]    In another of its aspects, the present invention provides a mold for producing a vehicular headliner, the mold comprising:  
           [0028]    a first mold half and a second mold half releasably engagable between an open position and closed position to define a mold cavity in the closed position;  
           [0029]    a seal disposed on at least one of the first mold half and the second mold half such that in the closed position of the mold, a substantially fluid tight seal is created between the mold cavity and an exterior thereof;  
           [0030]    a vacuum chamber interposed between the seal and the mold cavity, the vacuum chamber having a cross-sectional thickness which allows entry of gases produced during expansion of a liquid foam composition in the mold cavity but which prevents entry of the liquid foam composition;  
           [0031]    at least one ribbon vent interposed between the vacuum chamber and the mold cavity, the at least one ribbon vent comprising a passageway having a cross-sectional thickness which causes the liquid foam composition to enter the passageway. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0032]    Embodiments of the present invention will be described with reference to the accompanying drawings, in which:  
         [0033]    [0033]FIG. 1 illustrates a perspective view of an embodiment of the present mold;  
         [0034]    [0034]FIG. 2 illustrates an enlargement of a part-line vent disposed in the mold illustrated in FIG. 1;  
         [0035]    [0035]FIG. 3 illustrates a sectional view taken along line III-III in FIG. 2;  
         [0036]    [0036]FIG. 4 illustrates a sectional view taken along line IV-IV in FIG. 2;  
         [0037]    [0037]FIG. 5 illustrates aspects of the present process;  
         [0038]    [0038]FIG. 6 illustrates a perspective view of an embodiment of the present vehicular headliner; and  
         [0039]    [0039]FIG. 7 illustrates a schematic view of placement of the headliner in relation to occupants in a vehicle. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]    With reference to FIG. 1, there is illustrated a mold  100  comprising a lid  105  and a bowl  110 . Lid  105  and bowl  110  are interconnected by four guiderails  112 , 114 , 116 , 118 .  
         [0041]    As will be appreciated by those of skill in the art, mold  100  is not a so-called “clam shell” mold where a lid and a bowl are engagable by pivoting near the part line of the mold. Rather, in the case of mold  100 , the open and closed positions of the mold are achieved by appropriate upward (i.e., to open the mold) or downward (i.e., to close the mold) movement of lid  105  via guiderails  112 , 114 , 116 , 118 . The relative movement between lid  105  and bowl  110  can be achieved by any suitable means (not shown).  
         [0042]    In the illustrated embodiment, bowl  110  will shape and form the B-surface of the vehicular headliner whereas lid  105  will form and shape the A-surface of the vehicular headliner. Of course, if desired, this arrangement could be reversed.  
         [0043]    With continued reference to FIG. 1, lid  105  comprises a mold surface  120  which is designed to assume the shape of the A-surface of the finished vehicular headliner. Disposed within mold surface  120  are a plurality of apertures  165  (for clarity, only some of the apertures are illustrated). A fluid impermeable seal  125  (e.g., a rubber bumper, a foam bead or the like) is disposed on the periphery of lid  105 . As will be evident, seal  125  is substantially continuous about the perimeter of a surface of lid  105 . A part-line surface  130  is interposed between mold surface  120  and seal  125 .  
         [0044]    Bowl  110  comprises a mold surface  135 . Mold surface  135  comprises a pair of troughs  140 , 145  disposed generally longitudinally and adjacent to an edge of mold surface  135 . Mold surface  135  also comprises a plurality of apertures  165  (for clarity, only some of the apertures are illustrated). Interposed between troughs  140 , 145  is a form  150 .  
         [0045]    A part-line surface  155  is disposed on bowl  110 . A plurality of grooves  160  are disposed in part-line surface  155 .  
         [0046]    With reference to FIG. 2, there is illustrated an enlarged view of a peripheral portion of each of lid  105  and bowl  110  of mold  100 . As shown, each of part-line surfaces  130 , 155  comprise a plurality of apertures  165 . Apertures  165  are also disposed in grooves  160 .  
         [0047]    Apertures  165  are in communication with a chamber (not shown) within lid  105 . Emanating from this chamber are a series of hoses  170  which are connected to a vacuum source (not shown). Similarly, apertures  165  disposed in bowl  110  are in communication with a chamber(not shown) within bowl  110 . Emanating from this chamber are a series of hoses  175  which are connected to a vacuum source (not shown). As will be appreciated by those of skill in the art, it is possible to connect hoses  170  and hoses  175  to a common vacuum source (not shown) or independent vacuum sources (not shown).  
         [0048]    With further reference to FIG. 2, it will be seen that seal  125  is in substantial alignment with a marginal edge of part-line surface  155  of bowl  110  which does not comprise apertures  165 .  
         [0049]    With brief reference to FIGS. 3 and 4, it will be seen that, when lid  105  and bowl  110  are closed, two types of vent passageways are defined.  
         [0050]    In FIG. 3, seal  125  serves to define a so-called differential vent  180  formed between part-line surfaces  130 , 155 . In FIG. 4, in addition to a differential vent  180 , a so-called ribbon vent  185  is formed between part-line surface  130  and the major face of groove  160 .  
         [0051]    Preferably, ribbon vent  185  comprises a cross-sectional thickness in the range of from about 0.002 inches to about 0.030 inches, more preferably in the range of from about 0.005 inches to about 0.020 inches. The design of the vent component is described in more detail in U.S. Pat. Nos. 5,356,580 Re.36,413),5,482,721 (Re.36,572), and 5,587,183 [Clarke et al]. As set out the Clarke et al patents, the ribbon vent is sized to allow entry of some foamable material (this will be discussed in more detail hereinbelow).  
         [0052]    Differential vent  180  preferably has a cross-sectional thickness of less than about 0.002 inches. A vent of this size generally will allow venting of gases produced during the foaming reaction but is sufficiently small to inhibit substantially foam extrusion into the vent. In this manner, the vent acts as a differential vent allowing passage of gas, but inhibiting passage of foam.  
         [0053]    The operation of mold  100  will now be discussed.  
         [0054]    With reference to FIG. 5, various steps in the present process are illustrated in a single Figure for clarity-purposes. Of course, those of skill in the art will recognize that it is not necessary to conduct all of the steps simultaneously (although this could be done if convenient).  
         [0055]    Thus, the vacuum source (not shown) attached to hoses  170  is turned on thereby creating a sucking motion through apertures  165  in lid  105 . At this point, a cover stock material  190  is disposed in lid  105  in the direction of arrows A.  
         [0056]    The nature of cover stock  190  is not particularly restricted. Preferably, cover stock  190  comprises a laminate structure having a first outer layer and an inner layer. The first outer layer may be substantially permeable to air or substantially impermeable to air. Those of skill in the art will recognize that the first outer layer is adjacent mold surface  120  of lid  105  and the inner layer faces the mold cavity. The inner layer can comprise a cellular material or a non-cellular material or, in some cases, can be omitted entirely.  
         [0057]    The vacuum source (not shown) connected to hoses  175  is turned on thereby creating a sucking effect through apertures  165  in bowl  110 . It is preferred, at this point to apply a scrim or other layer over mold surface  135  of bowl  110 . The purpose of such a layer is to obviate or mitigate plugging of apertures  165  in bowl  110  by foam material which is poured into bowl  110 . The sucking effect created by the vacuum will shape the scrim or other layer to mold surface  135 .  
         [0058]    Next, a liquid foamable composition  195  is dispensed from a dispensing head  200 . It will be recognized that composition  195  may be sprayed or poured. Preferably, composition  195  is poured in troughs  140 , 145 . It is not necessary to dispense composition  195  over the entire surface of mold surface  135 .  
         [0059]    Once the appropriate amount of composition  195  has been dispensed into bowl  110 , lid  105  and bowl  110  are closed. By continuing to apply a vacuum through all of apertures  165  in lid  105  and bowl  110 , it will be recognized that, whereas apertures  165  on mold surfaces  120 , 135  are covered and the vacuum is used to hold the covering materials in place, apertures  165  disposed on part-line surfaces  130 , 155  act in combination to form an intermediate vacuum chamber around the perimeter (i.e., a perimeter differential vent) of the mold cavity defined by closing lid  105  and bowl  110 . This intermediate vacuum chamber serves to facilitate venting of gases produced during the foaming reaction and distribution of the foam to substantially fill the mold cavity.  
         [0060]    With reference to FIGS. 3 and 4, such venting serves to migrate the foam composition into ribbon vent  185  but not into differential vent  180 . This vacuum-assisted venting facilitates proper filling of the mold cavity without the requirement of applying a foamable composition over the entire surface of mold surface  135 .  
         [0061]    After foamable composition  195  expands and fills the mold cavity defined by closure of lid  105  and bowl  110 , the mold is opened and a vehicular headliner  205  is de-molded (see FIG. 6). With reference FIG. 6, headliner  205  comprises a pair of longitudinally extending energy management portions  208 , 210  which are disposed longitudinally and adjacent a peripheral longitudinal edge of headliner  205 . As is evident, energy management portions  208 , 210  are thicker in cross section than marginal portions  215 , 225 . Further, energy management sections  205 , 210  are thicker in cross section than a central portion  230  of headliner  205 . Disposed in central portion  230  is an aperture  235  which is produced by cutting out a portion of headliner weakened by form  150  in bowl  110  of mold  100 .  
         [0062]    As shown in FIG. 6, headliner  205  comprises a plurality of ribbons  235  which correspond to portions of foam which entered ribbon vent  185 . If the foam composition used in the process is an energy management foam composition, it is preferred to trim ribbon portions  235  from the periphery of headliner  205 . This can be achieved by any conventional means.  
         [0063]    After production of headliner  205 , the foam element therein has an indentation force deflection at 25% deflection in the range of from about 150 to about 4,000 pounds, more preferably from about 500 to about 2500 pounds, most preferably from about 900 to about 2000 pounds, when measured pursuant to ASTM 3574-B 1 .  
         [0064]    It will be appreciated by a person skilled in the art that it is only the foam element of the headliner of the present invention which is made of foam, preferably polyurethane foam, and it is this foam which should meet the ASTM test recited in the previous paragraph.  
         [0065]    After expansion of the liquid foamable composition  195 , the resultant foam is preferably a polyurethane foam. The polyurethane foam preferably has a specific gravity of less than about 0.40, more preferably in the range of from about 0.0.25 to about 0.25, preferably from about 0.10 to about 0.25. The preferred embodiment of foamable composition  195  comprises a liquid foamable polyurethane composition  195  having a free rise density of from about one to about twenty pounds per cubic foot, more preferably from about two to about eight pounds per cubic foot. For most mold foams, this would give use to a foam core having a density in the range of from about 1.5 to about 24 pcf, more preferably from about 2.5 to about 12 pcf.  
         [0066]    Non-limiting and preferred examples of suitable polyurethane foams for use in producing the present headliner are available from Woodbridge Foam Corporation under the tradename Enerflex.  
         [0067]    Generally, the polyurethane foam suitable for use in the present headliners and having desirable energy management characteristics may be produced from the following general non-limiting formulation:  
                                                           Component   Amount                                Polymer Polyol   100-0   parts       Polyol   0-100   parts       Crosslinker   0-30   parts/100 parts total polyol       Catalyst   0.05 to 3.5   parts/100 parts total polyol       Silicone Surfactants   0-1.5   parts/100 parts total polyol       H 2 O   0.5 to 4.5   parts/100 parts total polyol            Isocyanate   Adequate quantity for an index of from           about .60 to 1.30 ratio of NCO equivalents to           the equivalents of NCO reactive sites.                  
 
         [0068]    Suitable polymer polyols, polyols and isocyanates are described in U.S. Pat. Nos. 3,304,273, 3,383,351, 3,523,093, 3,939,106 and 4,134,610, Belgian patent 788,115, Canadian Patent 785,835 and “Polymer/Polyols, a New Class of Polyurethane Intermediate”, Kuryla, W. C. et al., J. Cellular Plastics, March (1966).  
         [0069]    Suitable crosslinkers, catalysts and silicone surfactants are described in U.S. Pat. Nos. 4,107,106 and 4,190,712.  
         [0070]    The preferred polyurethane foam suitable for use in the present head liner may be produced from the following formulation:  
                                   Component   Amount                   Polymer Polyol 1      20-100 parts       Polyol 2       0-80 parts       Crosslinker 3       5-15 parts/100 parts total polyol       Catalyst 4      0.5-1.2 parts/100 parts total polyol       Silicone Surfactants 5      0.3-1.1 parts/100 parts total polyol       H 2 O   1.75-2.75 parts/100 parts total polyol       Isocyanate 6     Adequate quantity for an index of from about           0.8 to 1.1 ratio of NCO equivalents to the           equivalents of NCO reactive sites.                                                                  
 
         [0071]    With reference to FIG. 7, a very schematic illustration is provided of placement of headliner  205  with reference to the location of occupants in a vehicle. Such a headliner can be designed to possess advantageous energy management properties thereby obviating or mitigating injuries to the occupants upon impact of the occupants and headliner  205 .  
         [0072]    While a specific embodiment of producing the present headliner has been shown with reference to the Figures, those of skill in the art will recognize that a number of modifications to the specific embodiment can be made without departing from the spirit and scope of the present invention. For example, the use of form  150  on mold  135  in the illustrated embodiment is optional and thus, may be omitted (e.g., if a dome light is not to be attached to the finished headliner). Still further, the design of troughs  140 , 145  can vary depending on factors such as the specific vehicle in the headliner is to be used, the specific requirements for the headliner in that vehicle and the like. For example, it is not necessary that the troughs continuous and longitudinal as illustrated. Still further, in some cases, it may be desirable to heat mold  100  during expansion of foamable composition  195  (e.g., depending on the chemical composition of foamable composition  195 . In such cases, hoses  170 , 175  may be used for this purposes and the vacuum applied to apertures  165  may be generated from other hoses, conduits and the like (not shown). Still further, it is possible to utilize a cover stock  190  having a cloth outer layer and a plastic inner layer and couple the use of such a cover stock with a post-production step of piercing or otherwise rendering breathable the inner layer of the cover stock. This can be achieved by any suitable means such as by using a plurality of needles applied to the cover stock of the finished part thereby piercing the inner layer interposed between the foam element and the finished cover. Alternatively, it is possible to utilize a cover stock comprising a finished outer layer and an inner layer which will disintegrate or otherwise become air permeable after production of the headliner. Still further, it is possible to include in the cover stock a layer of material which will confer advantageous sound absorbing properties to the resultant headliner. The use of such a layer would obviate the need to increase the thickness of the foam (as suggested by Komylo) to achieve advantageous sound absorbing properties. An example of such a sound absorbing layer could be polyester fibre mat, melamine-based foam, GC (density and permeability controlled flexible polyurethane) foam and the like applied to the finished cover stock material. Further, reinforcing layers or chopped fibre can be used at the surface of or disposed within the foam element to provide appropriate reinforcement, where necessary. Of course, the mold illustrated above can be modified to allow insertion of design components (e.g. clips, dome lights, wiring harnesses and the like) during production. Thus, various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments.  
         [0073]    All publications, patents and patent applications referred to herein are incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety.