May, 1931
INDUSTRIAL AND ENGINEERIAVG CHEMIXTRY
505
Manufacture and Characteristics of Laminated Glass’ Willard L. Morgan TRIP] E \ SAFETY GLASSCOMPANY OF NORTH~ V E R I C A CLIFTOVS J
.UlIS-ITED glass is a sandwich consisting of a layer public was rapid. Amory L. Haskell was very much impressed of plastic between two sheets of glass to which the with the life-protective value which laminated glass offered to sheet of plastic has been caused to adhere by the coni- the motorist, and RS a result of his determination to bring this bined effect of heat, pressure, and the application of special safeguard to the American people the Triplex Safety Glass materials. Both plate glass and drawn sheet glass are used. Company of E’orth America was incorporated under license Nitrocellulose has been used chiefly as the plastic sheet, al- from the British concern, who in 1923 had secured the world though in Europe cellulose acetate has been utilized to a small rights from the French Triplex concern. At the present time extent. For use as a window, the plastic must be as trans- the plant a t Clifton, N. J., is the largest of its kind in the parent as possible, but new developments in decorative novel- world. Previous to the last three years England had been the major producer of laminated glass, but the United States ties utilize sheets carrying colored designs. While laminated glass is a quarter of a century old, its de- is now leading by a considerable margin. At present there velopment on a large scale is a matter of the last few years. are a t least eleven concerns in this country interested in the The idea of laminated glass apparently originated with Woods production of safety glass. It has been variously estimated that from 33 to 65 per cent (4) in 1906, although the first practical safety glass was made by a Frenchman, Benedictus, in 1911. Benedictus has stated of all injuries received in automobile accidents are caused by (1) that, in brooding over an automobile accident in which an flying glass. Consequently, while the idea that there was a acquaintance had been seriously cut by flying glass, he sud- non-shatterable glass required considerable sales education denly remembered having once dropped a flask in which a a t first, the rapid adoption of this glass by the automotive lacquer solution had evaporated. While the flask cracked, companies has caused a rapid growth in the industry as indiall the glass particles remained fastened to the dry lacquer cated by the figures from the production of Triplex glass h,I n safety glass we depend upon security froin the dan- alone. P R O D U C T I O N OF TRIPLEX GLASSIN UNITED S T A T E S gers of flying glass splinters by reason of the fact that, while Square feet Year 1926 1.163 the glass will crack, all pieces will remain adherent to the plas50;OOO 1927 tic, which also operates to absorb the breaking force. 1928 2,000,000 1929 6,642,000 After developing several methods for producing laminated 1930 (first 6 months) 3,215,000 glass (g), Benedictus found that he secured best practical Owing to the severe slump in the automobile market startoperation where a film of gelatin was used on the interior glass surfaces to secure adhesion of the celluloid. The gelatin, ing late in 1929, the complete production for 1930 for the inhowever, was not used as an ordinary wet glue, but in a form dustry will show a decrease. However. 85 uer cent of the laminated glass used in dry to sight and touch this c o u n t r y d u r i n g which became adhesive 1930 was manufactured due to thermoplastic under the Triplex procflow under heat and ess. At the end of 1930 pressure (3). it was estimated that The major portion of 4,900,000 c a r s were all laminated glass has equipped with safety been made by this procglass in a t least the ess, a l t h o u g h o t h e r winds‘hield. This is m e t h o d s are in use, 18.5 per cent of all the In France it was made car registrations for b~ the Soci6tB du Verre 1930. This has grown Triplex on a small scale from a usage in apprevious to the TT’orld proximately 80 cars in War, but it was not un1926. til the war that any The automobile inco nsid e r a b le market, dustry, in spite of its was found for it. Dur-. present importance, is ing this period it Tias not the only outlet for used for such things as laminated glass. The airplane and automoThe Triplex Safety Glass Company Factory a t Clifton, N. J. present article, in addibile windshields, bullettion to discussing the proof glass for tanks, glass for submarines, battleship-bridge windows. and eye production of this glass, will summarize the development work blanks for gas masks and aviators’ goggles. In 1912 a British leading into new fields of utilization. The production methods group took over the manufacturing and sales rights for Great outlined below refer t o standard-quality laminated glass such Britain and its colonies from the French concern and the Tri- as that used in windshields, windows, and deflectors of the plex Safety Glass Company, Ltd., was organized. Successful ordinary automobile. production was established in 1914. After the war the market Triplex Manufacturing Operations in the automotive industry offered the most promise of development. Adoption of safety glass by the British motoring Glass sheets are cut to size by means of metal templates. Each piece of glass is wiped on one side by hand with a clesn1 Received March 30, 1931.
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l.vl~us7~ltl.~~ 1' .I'VU Ila&; and the control of tlic laminating process so that the safoty glass will not ilevelop (.oIor, brittleIIBSS; or bubbles and be as frec of ham as possible. As celluloid is quite hygroscopic, it is also essential that the glass edges be protected from the sel!arilting action of rain and hitmid conditions by a waterproof seal which must, he eqiia11y (4Tirient in cold a i d warm weather. The constunt battle against dirt has already becn 1netit,ilialilydevelop, particularly fnr sirch iiidiistrial uses as rnqiiirc greater resistance to hcat than celluloid affords. Tlie cellolose acetatc industry is still in an early stage, and material with improved properties a t reduced cost may lie available within a few years. It does not appcsr that cellulose acetate will displace celluloid for ordinary laminating purposes, such as automobile glass, until the acetate is irnp r o d by more satisfactory plusticiners. In addition to its use in private aiitonioiJiles, taxicabs, and busses, laniinat,ed glass is now finding an expanding market iii railway strrvice, where it is used for the windows in loconiotive cabs, in club and parlor cars, and in street-railway cars. It is also being cmpl(qwl industrially for machine
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I N D U S T R I A L A N D E.VGINEERING CHEiWISTRY
guards and windows on special test equipment. The uses developed during the war in the naval and air services also continue, and considerable multiple-layer laminated glass 1 to 11/4 inches in thickness is used as bullet-proof glass. All of these applications are based on the safety feature of laminated glass. A new field is now being developed, however, in which this feature is secondary and the emphasis is upon the artistic effects which may be obtained by using color and design in the sheet of plastic. Table tops, tray bottoms, mirrors, wall paneling, soda fountains, display signs and novelties, art placques and silhouettes designed in mirror, and many other products of extremely attractive appearance have already been placed on the market. Celluloid can now be printed satisfactorily in four colors, with future prospects of
Vol. 23, KO.5
additional variety if desired, so that marbles and grained and inlaid woods can be secured which rival the natural materials. The opportunities for new and striking artistic effects through the medium of laminated glass are numerous and future development of the industry may be quite as much along this line as along the established one of insuring safety. Literature Cited (1) Benedictus, E.,Glaces e l w r i e s , No. 18, 9 (Oct., 1930). (2) Benedictus, E.,U. S. Patents 1,098,342(May 26,1914); 1,128,094(Feb. 9,1915); 1,206,656(Nov. 28. 1916). (3) Benedictus. E.,U.S.Patent 1,182,739(May 9,1916). (4) Woods, J. C . , U S . Patent 830,398(Sept. 4, 1906).
Energy-Emission Data of Light Sources for Photochemical Reactions' C. E. Greider RESEARCH LABORATORY, NATIONAL
CARBON COMPANY, ISC
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ST, C L E V E L A N D ,
OHIO
Data are presented giving the amount and spectral IGHT sources, in the Light Sources distribution of the radiant energy from a number of ordinary meaning of typical carbon arcs, most of which are in common use the term, are now beThe sources commonly used at the present time. This information is essential ing used for many purposes for the production of visual for the selection of the most suitable light source for other than the production of light, as well as ultra-violet a reaction involving the use of ultra-violet or visual visual light. Physicians and and infra-red, fall into two light. It also illustrates the wide variety of types of clinical workers make use of classes. The first is represpectral-energy distribution that can be obtained from them for various therapeutic sented by incandescent solids, different types of carbon arcs. mmoses. lawnen for health which show an essentiallv con- maintenance, while technical tinuous spectrum of which the workers use light sources for a wide variety of photochemical conimonest illustration is the ordinary tungsten-filament lamp. and analytical reactions influenced by radiation in various The second is the discontinuous or line spectrum caused by the parts of the spectrum. thermal or electrical excitation of gas molecules, commonly In order to determine the effectiveness of a given source produced by an arc or other electrical discharge. of radiation for a specified purpose, it is not sufficient to Both types of radiation are found in the carbon arc. The measure its intensity simply in the broad bands of the spec- crater or electrode tip is heated to incandescence and shows trum designated as ultra-violet, visual, or infra-red, since the typical continuous spectrum of an incandescent solid, many of the effects of radiation are produced by relatively while the arc stream, between the two electrodes, givesoff the narrow portions of these bands. As an example, the actira- characteristic line or band spectrum of the molecules and tion of ergosterol to form vitamin D is brought about on$ atoms present in .the arc. The relative amounts of the two by ultra-violet of shorter wave length than about 3100 A. types of radiation can be varied a t will in accordance with the Since this in many sources constitutes only a small fraction purpose to which the arc is to be put; thus, the radiation of the total ultra-violet and may be practically absent in from the crater of the plain or projector carbon is almost some sources which contain appreciable amounts of ultra- all the continuous spectrum of the incandescent solid, while violet of longer wave length, a determination of ultra-violet from a true flame arc i t is practically all of the second type. intensity tells nothing of the value of a light source for this In this case the incandescent solid electrodes produce only a very small fraction of the total ultra-violet and visual light, purpose. The evaluation of a source of ultra-violet or visual light for most of which comes from the arc stream between the two any of its various purposes may be obtained from measure- electrodes. The difference between the two types of arc is ments of the intensity and distribution of energy throughout clearly shown in Figure 1, A and B. An arc between two pieces of pure carbon will show, in the spectrum. When the response curve of a reaction under consideration is known, the effectiveness of a given source addition to the radiation from the electrodes themselves, can be determined directly from its spectral-energy distribu- certain lines and bands, chiefly in the violet and near ultration curve by determining the intensity in that range of the violet, characteristic of the carbon arc in air. This distribuspectrum to which the material responds. When the response tion of energy can be modified by incorporating other matecurve is not known, information regarding it can be obtained rials in the carbon which are vaporized by the arc and add by comparing the effectiveness of two different sources whose their characteristic spectrum to that of the carbon itself. Such materials may be distributed throughout the electrode, spectral-energy distribution curves are known. but are more commonly concentrated in the center or core. 1 Received March 4, 1931. Presented before the Division of InThe flame carbon arc thus offers a very versatile source of dustrial and Engineering Chemistry at the 81st Meeting of the American radiation, for by changing the nature of the material in its Chemical Society, Indianapolis, Ind., March 30 t o April 3, 1931.
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