Stock material or miscellaneous articles – Hollow or container type article – Nonself-supporting tubular film or bag
Reexamination Certificate
1999-09-14
2003-02-18
Dye, Rena (Department: 3627)
Stock material or miscellaneous articles
Hollow or container type article
Nonself-supporting tubular film or bag
C428S036600, C428S036700, C428S036800, C428S339000, C428S423100, C428S424200, C036S028000, C036S03000A, C036S03500R, C036S044000, C156S244140, C156S244240
Reexamination Certificate
active
06521305
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to cushioning devices for footwear and, more particularly, to a gas-filled cushioning device which includes an elastomeric barrier material for selectively controlling the diffusion of inert gases while allowing controlled diffusion of gases normally contained in the atmosphere, with the cushioning device being particularly employed in footwear products.
BACKGROUND OF THE INVENTION
Shoes, and particularly athletic shoes, can be described as including two major categories of components namely, a shoe upper and a sole. The general purpose of the shoe upper is to snugly and comfortably enclose the foot. Ideally, the shoe upper should be made from an attractive, highly durable, yet comfortable material or combination of materials. The sole, which also can be made from one or more durable materials, is primarily designed to provide traction, and to protect the wearer's feet and body during any use consistent with the design of the shoe. The considerable forces generated during uses such as athletic activities require that the sole of an athletic shoe provide enhanced protection and shock absorption for the feet, ankles and legs of the wearer. For example, impacts which occur during running activities can generate forces of up to two to three times body weight; certain other activities, e.g., playing basketball, have been known to generate forces of up to approximately 6-10 times an individual's body weight. Accordingly, many shoes and, more particularly, many athletic shoe soles are now provided with some type of resilient, shock-absorbent material or shock-absorbent components to cushion the user during strenuous athletic activity. Such resilient, shock-absorbent materials or components have now commonly come to be referred to in the shoe manufacturing industry as the mid-sole.
More specifically, it has been a focus of the industry to seek a mid-sole design which achieves an effective impact response in which both adequate shock absorption and resiliency are appropriately taken into account. Such resilient, shock-absorbent materials or components could also be applied to the insole portion of the shoe, which is generally defined as the portion of the shoe upper directly underlining the plantar surface of the foot.
A specific focus in the shoe manufacturing industry has been to seek mid-sole or insert structure designs which are adapted to contain fluids, in either the liquid or gaseous state, or both. Examples of gas-filled structures which are utilized within the soles of shoes are shown in U.S. Pat. No. 900,867 entitled “Cushion for Footwear” which issued Oct. 13, 1908, to Miller; U.S. Pat. No. 1,069,001 entitled “Cushioned Sole and Heel for Shoes” which issued Jul. 29, 1913, to Guy; U.S. Pat. No. 1,304,915 entitled “Pneumatic Insole” which issued May 27, 1919, to Spinney; U.S. Pat. No. 1,514,468 entitled “Arch Cushion” which issued Nov. 4, 1924, to Schopf; U.S. Pat. No. 2,080,469 entitled “Pneumatic Foot Support” which issued May 18, 1937, to Gilbert; U.S. Pat. No. 2,645,865 entitled “Cushioning Insole for Shoes” which issued Jul. 21, 1953, to Towne; U.S. Pat. No. 2,677,906 entitled “Cushioned Inner Sole for Shoes and Method of Making the Same” which issued May 11, 1954, to Reed; U.S. Pat. No. 4,183,156 entitled “Insole Construction for Articles of Footwear” which issued Jan. 15, 1980, to Rudy; U.S. Pat. No. 4,219,945 entitled “Footwear” which issued Sept. 2, 1980, also to Rudy; U.S. Pat. No. 4,722,131 entitled “Air Cushion Shoe Sole” which issued Feb. 2, 1988, to Huang; and U.S. Pat. No. 4,864,738 entitled “Sole Construction for Footwear” which issued Sep. 12, 1989, to Horovitz; all of which are incorporated herein by reference. As will be recognized by those skilled in the art, such gas filled structures (often referred to in the shoe manufacturing industry as “bladders”) typically fall into two broad categories, namely (1) “permanently” inflated systems such as those disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 and (2) pump and valve adjustable systems as exemplified by U.S. Pat. No. 4,722,131. By way of further example, athletic shoes of the type disclosed in U.S. Pat. No. 4,182,156 which include “permanently” inflated bladders have been successfully sold under the trade mark “Air Sole” and other trademarks by Nike, Inc. of Beaverton, Oregon. To date, millions of pairs of athletic shoes of this type have been sold in the United States and throughout the world.
The permanently inflated bladders are typically constructed under methods using a flexible thermoplastic material which is inflated with a large molecule, low solubility coefficient gas otherwise referred to in the industry as a “super gas,” such as SF
6
. By way of example, U.S. Pat. No. 4,340,626 entitled “Diffusion Pumping Apparatus Self-Inflating Device” which issued Jul. 20, 1982, to Rudy, which is expressly incorporated herein by reference, discloses a pair of elastomeric, selectively permeable sheets of film which are formed into a bladder and thereafter inflated with a gas or mixture of gases to a prescribed pressure which preferably is above atmospheric pressure. Ideally, the gas or gases utilized have a relatively low diffusion rate through the selectively permeable bladder to the exterior environment while gases such as nitrogen, oxygen and argon (which are contained in the atmosphere and have a relatively high diffusion rate) are able to penetrate the bladder. This produces an increase in the total pressure within the bladder by the additive nature of the partial pressures of the nitrogen, oxygen and argon which diffuse into the bladder from the atmosphere and the partial pressures of the gas or gases contained initially injected into the bladder upon inflation. This concept of an almost total “one-way” addition of gases to enhance the total pressure of the bladder is now known in the art as “diffusion pumping.”
In a diffusion pumping system, there is a period of time involved before a steady state of internal pressure is achieved. The period of time is related to the bladder material used and the choice of gas or gases contained in the bladder. For example, oxygen tends to diffuse into the bladder rather quickly with the effect being an increase in the internal pressure of approximately 2.5 psi. In contrast, over the course of a number of weeks nitrogen gas will gradually diffuse into the bladder resulting in an increase of pressure to approximately 12.0 psi. This gradual increase in bladder pressure typically causes an increase in tension in the skin, resulting in a volume increase due to stretching. This effect is commonly referred to in the industry as “tensile relaxation” or “creep.” Thus, the initial selection of materials employed in the bladder and the choice of the captive gas or gas mixture utilized to initially inflate the bladder is critical to achieving a bladder which is essentially permanently inflated at a desired internal pressure and which therefore maintains a desired internal pressure over an extended period of time.
Prior to and shortly after the introduction of the Air Sole™ athletic shoes, many of the mid-sole bladders employed in the industry consisted of a single layer gas barrier type film made from polyvinylidene chloride based materials such as Saran® (which is a registered trademark of the Dow Chemical Co.). These materials which, by their nature are rigid plastics, are less than ideal from the standpoint of flex fatigue, heat sealability, elasticity, and degradation. Attempts to address these limitations by creating bladder films made by techniques such as laminations and coatings (which involve one or more barrier materials in combination with a flexible bladder material such as various thermoplastics) then present a wide variety of problems typical of such combinations. Such difficulties with composite constructions typically include layer separation; peeling; gas diffusion or capillary action at weld interfaces; low elongation which leads to wrinkling of the inflated product; cloudy appearing finished bl
Bonk Henry W.
Mitchell Paul H.
Sell, Jr. James C.
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