Boots – shoes – and leggings – Insoles – Laminated
Reexamination Certificate
1999-05-18
2001-03-13
Patterson, M. D. (Department: 3728)
Boots, shoes, and leggings
Insoles
Laminated
C036S00300B
Reexamination Certificate
active
06199304
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a sockliner and more particularly to a sockliner which cushions a foot while preserving a cool and dry environment for the foot.
When walking and running, various portions of the foot impact the ground at different times during the gait cycle. Generally, an outside (i.e., lateral) portion of the heel strikes the ground first, and the foot pivots on the heel to bring the outside portion of the forefoot into contact with the ground. From this position, the foot rapidly rotates inwardly to a neutral position in which the bottom of the heel and the forefoot are in contact with the ground. Thus, certain parts of the foot are subjected to repeated impact forces during walking and running. Moreover, these impact forces transfer to related anatomical features such as the shins and knees. Over time, these forces can cause pain and injury to the structures and tissue of the feet and the related anatomical features.
Foam sockliners frequently are used in shoes to attenuate the impact forces applied to the feet by the ground during walking and running. In the past, these sockliners frequently were made of closed cell polyurethane foam which offered excellent shock attenuation properties and durability. However, when closed cell foam is compressed, it generates heat due to a phenomena known as hysteresis. Moreover, the closed cell foam does not breathe well because it is substantially impermeable to air. Thus, closed cell foam sockliners heat the foot and do not keep the foot dry.
SUMMARY OF THE INVENTION
Among the several objects and features of the present invention may be noted the provision of a sockliner which provides cushioning to attenuate impact without heating the foot and while permitting the foot to breathe; and the provision of a method of making sockliners which permits a closed cell foam to be molded adjacent an open cell foam without substantially adversely affecting the breathability of the sockliner.
Briefly, apparatus of this invention is a laminated foam sockliner for use in combination with footwear to cushion a foot inserted in the footwear. The sockliner comprises a compressibly resilient closed cell foam lower layer having top and bottom surfaces sized and shaped for insertion into the footwear and for supporting at least a portion of the foot. The lower layer has a compressibility sufficient to permit the layer to resiliently compress under the foot in response to pressure applied to the layer by the foot during periods of a gait cycle when the footwear impacts the ground thereby absorbing shock and cushioning the foot during impact. The sockliner further comprises an open cell foam upper layer having top and bottom surfaces sized and shaped for insertion in the footwear. The bottom surface of the upper layer is permanently bonded to the top surface of the lower layer for spacing the lower layer from the foot to reduce heat transfer from the lower layer to the foot and insulate the foot from thermal energy generated by the lower layer in response to compression of the lower layer by the foot during the gait cycle.
In another aspect of the invention, the sockliner comprises a compressibly resilient closed cell foam lower layer and a porous upper layer fashioned from a flexible material which is permeable to air having top and bottom surfaces sized and shaped for insertion in the footwear. The bottom surface of the upper layer is permanently bonded to the top surface of the lower layer. The upper layer has a plurality of openings extending upward from the bottom surface aligned with the openings extending through the lower layer for permitting air to pass through the upper and lower layers to cool and dry the foot.
In yet another aspect, the present invention is a method of manufacturing a sockliner for use in combination with footwear to cushion a foot inserted in the footwear. The method comprises the step of continuously applying a porous adhesive substance to at least one of a bottom surface of a cloth layer and a top surface of an open cell foam upper layer. Further, the method includes the steps of marrying the cloth layer and the upper layer to permanently bond the upper layer and the cloth layer, cutting the cloth layer and the upper layer to a size and shape for insertion into the footwear and for supporting at least a portion of the foot, and compression molding the bonded upper layer and the cloth layer in a first mold to partially close exposed open cells in a bottom surface of the upper layer. The method also includes the steps of removing the compression molded upper layer and the cloth layer from said first mold, and inserting the compression molded upper layer and the cloth layer into a second mold. In addition, the method comprises the step of pouring a polyurethane onto the bottom surface of the upper layer in the second mold. Still further, the method includes the steps of foaming the polyurethane to form a closed cell foam lower layer adjacent the upper layer, and removing the cloth layer, the upper layer and the lower layer from the second mold.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.
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Nine West Group Inc.
Patterson M. D.
Senniger Powers Leavitt & Roedel
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