Gore-Tex is a waterproof/breathable fabric, and a registered trademark of W. L. Gore and Associates. It was co-invented by Wilbert L. Gore, Rowena Taylor, and Gore's son, Robert W. Gore. Robert Gore was granted U.S. Patent 3,953,566 on April 27, 1976, for a porous form of polytetrafluoroethylene (the chemical constituent of Teflon) with a micro-structure characterized by nodes interconnected by fibrils. Robert Gore, Rowena Taylor, and Samuel Allen were granted U.S. Patent 4,194,041 on March 18, 1980 for a "waterproof laminate." For its invention, Robert W. Gore was inducted into the National Inventors Hall of Fame in 2006.[1]
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In 1966, John W. Cropper of New Zealand developed and constructed a machine for producing stretched PTFE tape. Rather than file for a patent, however, Cropper chose to keep the process of creating expanded PTFE as a closely held trade secret and required his producer and its employees to sign confidentiality agreements.[2]
In 1969, Bob Gore independently discovered expanded polytetrafluoroethylene (ePTFE) and introduced it to the public under the trademark Gore-Tex,[3] for which he promptly applied for and obtained U.S. Patent 3,953,566, issued April 27, 1976 and U.S. Patent 4,187,390, issued February 5, 1980.
In the 1970s Garlock, Inc. infringed Gore's patents and was promptly sued by Gore in the Federal District Court of Ohio. After a "bitterly contested case" that "involved over two years of discovery, five weeks of trial, the testimony of 35 witnesses (19 live, 16 by deposition), and over 300 exhibits," (quoting the Federal Circuit) the District Court held Gore's patents to be invalid. On appeal, however, the Federal Circuit disagreed in the famous case of Gore v. Garlock, reversing the lower court's decision on the ground, inter alia, that Cropper forfeited any superior claim to the invention by virtue of having concealed the process for making ePTFE from the public, thereby establishing Gore as the legal inventor.[4]
PTFE is made using an emulsion polymerization process that utilizes the fluorosurfactant PFOA,[5][6] a persistent environmental contaminant. As Gore-Tex is PTFE-based, PFOA is used in its production.[7]
Gore-Tex materials are typically based on thermo-mechanically expanded polytetrafluoroethylene (PTFE) and other fluoropolymer products. They are used in a wide variety of applications such as high performance fabrics, medical implants, filter media, insulation for wires and cables, gaskets, and sealants. However, Gore-Tex fabric is best known for its use in protective, yet breathable, rainwear.
The simplest sort of rain wear is a two layer sandwich. The outer layer is typically nylon or polyester and provides strength. The inner one is polyurethane (abbreviated: PU), and provides water resistance, at the cost of breathability.
Early Gore-Tex fabric replaced the inner layer of PU with a thin, porous fluoropolymer membrane (Teflon) coating that is bonded to a fabric. This membrane had about 9 billion pores per square inch (around 1.4 billion pores per square centimeter). Each pore is approximately 1/20,000 the size of a water droplet, making it impenetrable to liquid water while still allowing the more autonomous water vapour molecules to pass through.
More recent fabrics such as eVent, Nikwax Analogy and Epic avoid the need for this inner PU coating[8] and have been shown to have higher breathability as a result, while still being rainproof.[9]
Both wear and cleaning will reduce the performance of Gore-Tex clothes by wearing away the Durable Water Repellent (DWR) treatment on the surface of the fabric. The DWR prevents the face fabric from becoming wet and thus reducing breathability. However, the DWR is not responsible for the jacket being waterproof. This is a common misconception, so when the face fabric becomes soaked due to an absence of DWR, there is no breathability and the wearer's sweat will cause condensation to form inside the jacket. This may give the appearance that a jacket is leaking when it is not. The DWR can be reinvigorated by tumble drying the garment or ironing on a low setting..[10]
Gore requires that all garments made from their material have taping over the seams, to eliminate leaks. Gore's sister product, Windstopper, is similar to Gore-Tex in being windproof and breathable, but has ability to stretch and is not waterproof.
Gore-Tex is also playing an increasing role in the conservation of illuminated manuscripts.[11]
Explosive sensors have been printed on Gore-Tex clothing leading to the sensitive voltammetric detection of nitroaromatic compounds.[12]
The Gore naming system does not imply specific technology or material but instead specific set of performance characteristics.[13]
The "Gore-Tex" brand name was formerly used for industrial and medical products.[14][15]
Now that the main Gore-Tex patent has expired, there are several other products on the market with similar characteristics that use similar technology.[16]