|
|Section2= |Section7= }} Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. The best known brand name of PTFE-based formulas is Teflon by DuPont Co., which discovered the compound. PTFE is a fluorocarbon solid, as it is a high-molecular-weight compound consisting wholly of carbon and fluorine. PTFE is hydrophobic: neither water nor water-containing substances wet PTFE, as fluorocarbons demonstrate mitigated London dispersion forces due to the high electronegativity of fluorine. PTFE has one of the lowest coefficients of friction against any solid. PTFE is used as a non-stick coating for pans and other cookware. It is very non-reactive, partly because of the strength of carbon–fluorine bonds and so it is often used in containers and pipework for reactive and corrosive chemicals. Where used as a lubricant, PTFE reduces friction, wear and energy consumption of machinery. It is also commonly used as a graft material in surgical interventions. == History == PTFE was accidentally discovered in 1938 by Roy Plunkett while he was working in New Jersey for DuPont. As Plunkett attempted to make a new chlorofluorocarbon refrigerant, the tetrafluoroethylene gas in its pressure bottle stopped flowing before the bottle's weight had dropped to the point signaling "empty." Since Plunkett was measuring the amount of gas used by weighing the bottle, he became curious as to the source of the weight, and finally resorted to sawing the bottle apart. He found the bottle's interior coated with a waxy white material that was oddly slippery. Analysis showed that it was polymerized perfluoroethylene, with the iron from the inside of the container having acted as a catalyst at high pressure. Kinetic Chemicals patented the new fluorinated plastic (analogous to the already known polyethylene) in 1941, and registered the Teflon trademark in 1945. By 1948, DuPont, which founded Kinetic Chemicals in partnership with General Motors, was producing over two million pounds (900 tons) of Teflon brand PTFE per year in Parkersburg, West Virginia.〔American Heritage's Invention & Technology, Fall 2010, vol. 25, no. 3, p. 42〕 An early use was in the Manhattan Project as a material to coat valves and seals in the pipes holding highly reactive uranium hexafluoride at the vast K-25 uranium enrichment plant in Oak Ridge, Tennessee.〔 〕 In 1954, the wife of French engineer Marc Grégoire urged him to try the material he had been using on fishing tackle on her cooking pans. He subsequently created the first Teflon-coated, non-stick pans under the brandname Tefal (combining "Tef" from "Teflon" and "al" from aluminum).〔"(Teflon History )", ''home.nycap.rr.com'', Retrieved 25 January 2009.〕 In the United States, Marion A. Trozzolo, who had been using the substance on scientific utensils, marketed the first US-made Teflon-coated pan, "The Happy Pan", in 1961.〔Robbins, William (21 December 1986) "(Teflon Maker: Out Of Frying Pan Into Fame )", ''New York Times'', Retrieved 21 December 1986 (Subscription)〕 However, Tefal was not the only company to utilize PTFE in nonstick cookware coatings. In subsequent years, many cookware manufacturers developed proprietary PTFE-based formulas, including Swiss Diamond International, which uses a diamond-reinforced PTFE formula,〔(Swiss Diamond Technology ) Swiss Diamond International〕 Scanpan which uses a titanium-reinforced PTFE formula,〔(About SCANPAN ) SCANPAN〕 and All-Clad〔(FAQ's ) "Is Nonstick Safe," All-Clad FAQ〕 and Newell Rubbermaid's Calphalon which use a non-reinforced PTFE-based nonstick.〔(FAQ's ) "Does your cookware contain Teflon®?" Calphalon FAQ〕 Other cookware companies, such as Meyer Corporation's Anolon, use Teflon〔(Knowledge Base ) Analon〕 nonstick coatings purchased from DuPont. In the 1990s, it was found that PTFE could be radiation cross-linked above its melting point in an oxygen-free environment. Electron beam processing is one example of radiation processing. Cross-linked PTFE has improved high-temperature mechanical properties and radiation stability. This was significant because, for many years, irradiation at ambient conditions had been used to break down PTFE for recycling.〔(Electron Beam Processing of PTFE ) E-BEAM Services website. Accessed May 21, 2013〕 The radiation-induced chain scission allows it to be more easily reground and reused. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Polytetrafluoroethylene」の詳細全文を読む スポンサード リンク
|