Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Nonwoven fabric – Including a foamed layer or component
Reexamination Certificate
1998-04-10
2001-03-20
Cole, Elizabeth M. (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Nonwoven fabric
Including a foamed layer or component
C442S370000, C442S373000, C428S317100, C428S354000, C428S3550EP
Reexamination Certificate
active
06204209
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to vehicle headliners and a method of forming vehicle headliners, and more particularly to vehicle headliners comprising a plurality of thermoformable layers which are compressed and molded to form a laminate having a predetermined contoured shape.
Many vehicle headliners have been constructed utilizing resin impregnated glass fiber. A resin impregnated glass fiber batt is compression molded into the desired headliner shape, and the resin is cured to maintain the molded shape. A thin layer of foam, such as polyurethane, overlies the molded fiberglass shape, and fabric is attached to the foam to form the exposed interior surface of the headliner. Because the glass fiber reinforced layer of such headliners is a rigid, often impermeable layer, it tends to reflect sound. Accordingly, undesirable ambient noises, including noise from the engine compartment or drive train, which enter the cabin are not absorbed by the headliner, but instead are reflected back into the cabin by the fiber reinforced resin layer.
Another type of vehicle headliner is prepared by thermoforming a laminate comprised of a stiff structural, yet thermoformable polystyrene foam layer and layers of kraft paper or a polymer film material bonded to either side of the foam. This laminate is covered with a soft foam backed fabric. Such headliners do not have sufficiently desirable sound absorbing properties because the kraft paper or polymer film tends to reflect sound rather than absorb sound.
A sound absorbing laminate which is useful for forming three-dimensionally contoured articles such as automobile headliners, and which exhibits substantially improved sound absorbing properties, is disclosed in U.S. Pat. No. 5,068,001, the rights of which have been assigned to Prince Corporation, Holland, Mich., the Assignee of the present invention. The laminate is comprised of a resilient, porous fibrous core layer, to which is adhered a fibrous, porous reinforcing mat to give the composite strength. The three-dimensional sound absorbing structure is generally formed by providing a first reinforcing porous, fibrous mat, providing a core defined by a resilient thermoformable porous fiber batt having a thickness of at least about ¼ inch, laminating the mat to one surface of the batt by impregnating the mat and its interface with the batt with sufficient binder resin to effect adherence therebetween, but insufficient resin binder to form a porosity-blocking film, and thermoforming the laminate into a porous three-dimensional configuration. While the sound absorbing laminate described in U.S. Pat. No. 5,068,001 provides substantially improved sound absorbing properties as compared with other known vehicle headliner constructions, vehicle manufacturers desire even better sound absorbing properties, and in particular desire headliner constructions which are capable of exhibiting excellent sound absorbing properties for particular frequency ranges depending on the characteristics of the vehicle. Also, while the method described in U.S. Pat. No. 5,068,001 is useful for mass producing automobile headliners on automated equipment, the amount of time which the laminate must remain in either a thermoforming molding tool or placed in a cooling fixture having a shape substantially identical with that of the molding tool, in order to form a high quality headliner in the desired three-dimensionally contoured configuration, can be more than is desirable.
SUMMARY OF THE INVENTION
In the present invention, it has been surprisingly found that substantially improved sound absorbing characteristics can be achieved, and that enhanced sound absorbing properties for a particular selected range of sound frequencies can be achieved using a laminate comprising a porous fibrous layer and a porous rigid foam layer. The combination of a porous fibrous layer and a rigid foam layer has been found to provide improved sound absorbing characteristics over substantially the entire range of sound frequencies which can be detected by the human ear. Additionally, the inventors have found that by varying the thickness of the layers and by varying the porosity and density of the rigid foam layer, the headliner can be tuned to exhibit specially enhanced sound absorbing properties for a particularly selected range of frequencies.
In addition to achieving improved sound absorbing characteristics, the three dimensionally contoured panels of the invention can be mass produced at higher production rates, and therefore at a lower cost. More specifically, it has been found that the rigid foam layer helps retain the desired three-dimensionally contoured shape at a higher temperature, whereby the thermoformed three-dimensionally contoured panel can be removed from the thermoforming molding tool at a higher temperature. As a result, shorter cycling times are required and more three-dimensionally configured panels can be produced per unit time for a given thermoforming molding tool.
Another advantage with the present invention is that the laminate comprising a porous fibrous core layer and a rigid foam layer can be thermoformed using the same thermoforming molding tools which are used for producing the three-dimensionally contoured panels described in U.S. Pat. No. 5,068,001. These and other objects, advantages and features of the present invention will be more fully understood and appreciated by reference to the written specification and appended drawings.
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Beard Dennis J.
Jung Christoph
Knorr Marie-Christine
Rozek Harry J.
Cole Elizabeth M.
Johnson Controls Technology Company
Price Heneveld Cooper DeWitt & Litton
Ruddock Ula C.
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