Membranes of polyurethane based materials including...

Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Layered – stratified traversely of length – or multiphase...

Reexamination Certificate

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C264S176100, C428S423100, C428S424800, C428S424600, C428S424700, C428S424400, C428S423500, C428S423300

Reexamination Certificate

active

06797215

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to membranes and, more particularly, to membranes which, under certain embodiments, serve to selectively control the diffusion of gases through the membrane. Additionally, the membrane not only selectively controls the diffusion of gases through the membrane, but also allows for the controlled diffusion of gases normally contained in the atmosphere.
BACKGROUND OF THE INVENTION
Membranes, and more particularly, membranes useful for containing fluids, including liquids and/or gases, in a controlled manner, have been employed for years in a wide variety of products ranging from bladders useful in inflatable objects, including vehicle tires and sporting goods for example; to accumulators used on heavy machinery; to cushioning devices useful in footwear. Regardless of the intended use, membranes must generally be flexible, resistant to environmental degradation and exhibit excellent gas transmission controls. Often, however, materials which exhibit acceptable flexibility characteristics tend to have an unacceptably low level of resistance to gas permeation. In contrast, materials which exhibit an acceptable level of resistance to gas permeation tend to have an unacceptably low level of flexibility.
In an attempt to address the concerns of both flexibility and imperviousness to gases, U.S. Pat. No. 5,036,110 which issued Jun. 30, 1991, to Moreaux describes resilient membranes for fitting hydropneumatic accumulators. According to Moreaux '110, the membrane disclosed consists of a film formed from a graft polymer which is the reaction product of an aromatic thermoplastic polyurethane with a copolymer of ethylene and vinyl alcohol, with this film being sandwiched between layers of thermoplastic polyurethane to form a laminate. While Moreaux '110 attempts to address the concerns in the art relating to flexibility and imperviousness to gases, a perceived drawback of Moreaux is that the film described is not processable utilizing conventional techniques such as sheet extrusion, for example. Thus, the present invention is directed to membranes which are flexible, have good resistance to gas transmission, and under certain embodiments are processable into laminates utilizing conventional techniques such as sheet extrusion which are highly resistant to delamination.
While it should be understood by those skilled in the art upon review of the following specification and claims that the membranes of the present invention have a broad range of applications, including but not limited to bladders for inflatable objects such as footballs, basketballs, soccer balls, inner tubes; substantially rigid flotation devices such as boat hulls; flexible floatation devices such as tubes or rafts; as a component of medical equipment such as catheter balloons; fuel lines and fuel storage tanks; various cushioning devices such as those incorporated as part of an article of footwear or clothing; as part of an article of furniture such as chairs and seats, as part of a bicycle or saddle, as part of protective equipment including shin guards and helmets; as a supporting element for articles of furniture and, more particularly, lumbar supports; as part of a prosthetic or orthopedic device; as a portion of a vehicle tire and particularly, the outer layer of the tire, as well as being incorporated as part of certain recreation equipment such as components of wheels for in-line or roller skates, to name a few, still other applications are possible. For example, one highly desirable application for the membranes of the present invention include their use in forming accumulators which are operable under high pressure environments such as hydraulic accumulators as will be discussed in greater detail below.
For convenience, but without limitation, the membranes of the present invention will hereinafter generally be described in terms of either accumulators or in terms of still another highly desirable application, namely for cushioning devices used in footwear. In order to fully discuss the applicability of the membranes in terms of cushioning devices for footwear, a description of footwear in general is believed to be necessary.
Footwear, or more precisely, shoes generally include two major categories of components namely, a shoe upper and the 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 particularly designed to provide traction and protect the wearer's feet and body during use. The considerable forces generated during 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 2-3 times the body weight of an individual while certain other activities such as, for example, 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 shoes 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 midsole.
It has therefore been a focus of the industry to seek midsole designs which achieve 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 particular focus in the footwear manufacturing industry has been to seek midsole 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. Nos. 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 Sep. 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. 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, Oreg. To date, millions of pairs of athletic shoes of this typ

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