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Laminated glass is a type of safety glass that holds together when shattered. In the event of breaking, it is held in place by an interlayer, typically of polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA), between its two or more layers of glass. The interlayer keeps the layers of glass bonded even when broken, and its high strength prevents the glass from breaking up into large sharp pieces. This produces a characteristic "spider web" cracking pattern when the impact is not enough to completely pierce the glass. In the case of the EVA, the thermoset EVA, offers a complete bounding (cross-linking) with the material whether it is glass, polycarbonate, P.E.T. or other types products. Laminated glass is normally used when there is a possibility of human impact or where the glass could fall if shattered and also for architectural applications. Skylight glazing and automobile windshields typically use laminated glass. In geographical areas requiring hurricane-resistant construction, laminated glass is often used in exterior storefronts, curtain walls and windows. Laminated glass is also used to increase the sound insulation rating of a window, where it significantly improves sound attenuation compared to unlaminated glass panes of the same thickness. For this purpose a special "acoustic PVB" compound is used for the interlayer. In the case of the EVA material, no additional acoustic material is required, since the EVA provides sound insulation. An additional property of laminated glass for windows is that a PVB and EVA interlayer can block essentially most ultraviolet radiation. A thermoset EVA could block up to 99,9% of the UV rays. ==History== In 1902, the French ''Le Carbone'' corporation obtained a patent for coating glass objects with celluloid in order to render them less susceptible to cracking or breaking.〔Le Carbon, S.A., French patent no. 321,651 (registered: May 31, 1902). See also: Jean-Marie Michel (April 27, 2012) ''Contribution à l'Histoire Industrielle des Polymères en France'', (Société Chimique de France, 2012), (Chapter A3: Le verre renforcé Triplex, page 1 ) (in French).〕 Laminated glass was invented in 1903 by the French chemist Édouard Bénédictus (1878-1930), inspired by a laboratory accident. A glass flask had become coated with the plastic cellulose nitrate and when dropped shattered but did not break into pieces.〔Édouard Bénédictus (October 1930), ''Glaces et verres; revue technique, artistique, pratique'', 3 (18): 9. The relevant quote is reprinted (in French) in: Jean-Marie Michel (April 27, 2012) ''Contribution à l'Histoire Industrielle des Polymères en France'', published on-line by the (Société Chimique de France ), see (Chapter A3: Le verre renforcé Triplex, page 7. )〕 However, it was not until 1909 that Benedictus filed a patent.〔French patent 405,881 (registered November 25, 1909).〕 In 1911, he formed the ''Société du Verre Triplex'', which fabricated a glass-plastic composite to reduce injuries in car accidents.〔Michel (2012), pp. 1,2.〕 Production of Triplex glass was slow and painstaking, making it expensive. It was not immediately widely adopted by automobile manufacturers, but laminated glass was widely used in the eyepieces of gas masks during World War I. In 1912, the process was licensed to ''The English Triplex Safety Glass Company''. Subsequently, in the United States, both Libbey Owens-Ford and Du Pont de Nemours with Pittsburg Plate Glass produced Triplex.〔Michel (2012), p. 2.〕 Meanwhile, in 1905, John Crewe Wood, a solicitor in Swindon, Wiltshire, England, patented a laminated glass for use as windscreens / windshields. The layers of glass were bonded together by Canada balsam.〔John Crewe Wood, ("Transparent screen," ) (filed: March 12, 1906 ; issued: Sept. 4, 1906).〕 In 1906 he founded the Safety Motor Screen Co. to produce and sell his product.〔David Burgess-Wise, "A good idea at the time: Safety Motor Screen," ''The Telegraph'' (U.K.), December 1, 2001. Available on-line at: (''The Telegraph'' )〕 In 1927, the Canadian chemists Howard W. Matheson and Frederick W. Skirrow invented the plastic polyvinyl butyral (PVB).〔Howard W. Matheson and Frederick W. Skirrow, ("Vinyl ester resins and process of making same," ) (filed: August 15, 1927 ; issued: August 20,Edouard Benedictus 1929).〕 By 1936, United States companies had discovered that laminated "safety glass" consisting of a layer of polyvinyl butyral between two layers of glass would not discolor and was not easily penetrated during accidents. Within five years, the new safety glass had virtually replaced its predecessor.〔Earl L. Fix, ("Safety glass," ) (filed: February 25, 1936 ; issued: June 23, 1936)〕〔Fred Aftalion, ''A History of the International Chemical Industry'', 2nd ed. (Philadelphia, Pennsylvania: Chemical Heritage Foundation, 2001), (p. 153. )〕 In the Road Traffic Act of 1930, the British parliament required new cars to use windscreens of "safety glass".〔Alan Irwin, ''Risk and the Control of Technology: Public Policies for Road Traffic Safety in Britain and the United States'' (Manchester, England: Manchester University Press, 1985), (p. 197. )〕 By 1939 some of "Indestructo" safety glass was being used every year in vehicles produced at the Ford Motor Company works in Dagenham, England. "Indestructo" safety glass was manufactured by British Indestructo Glass, Ltd. of London.〔 This was the laminated glass used by the Ford Motor Company in 1939, chosen because "it gives the most complete protection. In addition to being splinter-proof, it is crystal clear and permanently non-discolourable."〔 This quote hints at some of the technical issues, problems and concerns that stopped laminated glass from being widely used in automobiles immediately after it was invented. Modern laminated glass is produced by bonding two or more layers of ordinary annealed glass (or tempered glass) together with a plastic interlayer, usually polyvinyl butyral or ethylene-vinyl acetate (EVA). The PVB or the EVA are sandwiched by the glass, which is either passed through a series of rollers, or vacuum bagging systems, and ovens, or autoclaves, to expel any air pockets. Then it is heated to form the initial melting. These constructions are then heated under pressure in an autoclave or oven, to achieve the final bounded product(fully crosslinked in the case of the thermoset EVA). The tint at the top of some car windshields is in the PVB. Also, colored P.E.T. films can be combined with the thermoset EVA material, during the laminating process, in order to obtain a colored glass. Once a thermoset EVA is properly laminated during the process, the glass could be exposed frameless and there will be no water/moisture infiltration, the yellowing index is very low and it shouldn't delaminate, due to the high level of bounding (crosslinking). 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「Laminated glass」の詳細全文を読む スポンサード リンク
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