The U.S. office copying industry is undergoing dramatic changes. Most pronounced is the trend to dry copying methods and greater automation
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special report C&EN
IN OFFICE COPYING Thirty years ago, a company that owned its own office copying machine could count itself among the select and venturesome few. It was rather like a company today that operates its own interoffice network of closed-circuit television—intriguingly modern, but nevertheless an oddity. Not too many years ago, copying devices were viewed as luxuries that only the largest, most expensively equipped offices could possibly afford or justify. Now, few offices in the country are without at least one of these machines. Some have a dozen or more. Throughout the U.S., more than a half million of these devices are in use, spewing out copies at a rate of about 10 billion a year. In the short span of a decade, the copying machine has become just about as indispensable in the modern business office as the typewriter and the telephone. The astonishing growth of office copying is reflected in the fast-rising sales of copying machines and supplies
In the copying field today, a lively growth area is electrostatic machines based on the Electro fax process. Here, Bruning's Copytron 2000 electrostatic copiers are being checked before shipment
(sensitized papers, processing chemicals, and so on). In 1952, these combined sales amounted to less than $50 million. By 1960, they had climbed to about $200 million. This year, they are expected to reach $450 million. Currently growing at a rate of about 20% a year, the sales of the office copying industry are expected to exceed $700 million by 1968. Between 70 and 7 5 % of the industry's total sales are represented by supplies. These call for large quantities of silver halides, photographic developers, diazonium salts, stearates, carbon black, dyes, paper-processing chemicals, resins, zinc oxide, and a host of other chemicals. Although recent declines in the use of wet copying methods have reduced the industry's requirements for silver halides and other conventional photographic chemicals, its demands for numerous other chemicals have been steadily on the increase. Like many other terms, "office copying" is not too rigidly defined. In general, it is the use of an exposing device and an image-forming process to create full-size or essentially fullsize copies of an existing original. As commonly used, the term does not include the copying of large documents, such as engineering drawings. Normally, an office copying machine makes anywhere from one to 10 copies.
Office copying is sometimes confused with duplicating. Duplicating is the use of a device to make copies from a specially prepared master, such as a Mimeograph stencil or a Multilith mat. Generally, a duplicating machine produces anywhere from 10 to 10,000 or more copies. These distinctions in terms of volume of output are sometimes blurred, however. In some cases, a copying machine is called upon to turn out so many copies of a single original that it is actually performing the function of a duplicating machine —at excessive cost. Most office copying devices produce copies for between 1 and 10 cents a copy. Most duplicating machines turn out copies (above a certain minimum) for less than half a cent a copy. Today, more than 40 U.S. companies supply office copying machines. In 1963, the leading firms had these
This is the first of a two-part series on office copying machines and methods. Part 2, which will appear next week, will cover the electrostatic processes. It will also explore the many new techniques now in the research and development stage—some of which may have a profound effect on office copying of the future. JULY
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estimated sales or rentals of copying machines and supplies: Xerox Corp. Minnesota Mining & Mfg. Co. Eastman Kodak Co. American Photocopy Equipment Co. SCM Corp. Anken Chemical & Film Corp. Charles Bruning Co., a division of AddressographMultigraph Co.
office
$150 million** 80 million 42 million* 28 million 17 million 12 million
8 million0
« Includes about $10 million in sales of office copying products for nonelectrostatic processes. 6 Represents the office copying sales of Kodak itself, not the sales of its independent franchised dealers. c Includes office copying machines and supplies for both the diazo and electrostatic processes.
Together, these seven companies, with office copying sales of $337 million, accounted for more than 80% of the industry's total. Besides these and other U.S. firms that sell both copying machines and supplies, there are dozens of others that market only the supplies. These include Peerless Photo Products, Andrews Paper & Chemical, Photek Division of Orchard Paper, Kilborn Photo Paper, Interchemical, and many others. Office copying firms are overwhelmingly confident that the field is headed for continued rapid growth. As one spokesman puts it, "Office copying machines have become absolutely essential to industry in coping with the unrelenting torrent of paper work. Without question, the use of copiers will increase. Actually, these machines are just another form of office the automation—effectively taking place of secretaries, typewriters, and carbon paper. In some companies, copying devices have practically eliminated the need for typing pools." The demand for office copying is growing markedly as users become more and more conscious of the need for fast, accurate communication. Its use is also increasing as American companies expand nationwide and world-wide and as they see more clearly than ever the need for disseminating information efficiently. Many companies that originally bought an office copying machine to make copies of business correspondence and perhaps interoffice memos now find that these devices are also indispensable in copying reports, magazine articles, newspaper clip116
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pings, drawings—in fact, printed matter of all types. At the same time, a growing number of companies are also using copying machines in the routine processing of business forms —purchase orders, bills, inventory records, production reports, job orders, equipment requisitions. And in the future, an important growth area is expected to be the use of copying machines as integral parts of large-scale automatic information-retrieval systems. Underscoring the need for office copying is the rising cost of secretarial help. The cost of having a secretary type a single page usually amounts to about 70 cents and sometimes much more. Having a copying machine copy a page seldom costs more than 10 cents—and with no errors. However, as many producers of office copying equipment see it, the factors that really sell most customers on a copying machine are not so much the expected cost savings but the machine's speed and simplicity of operation—just the sheer convenience of the thing. Preference for Dry Copies For the office copying industry, the past few years have been a period of radical change. By far the biggest development has been the marked swing to dry copying methods based on electrostatics. The electrostatic method, used only to a very limited extent before 1960, has swept the field. This year, about half of all .office copies made in the U.S. will be produced electrostatically. Pre-eminent in the electrostatic field is Xerox Corp. Mainly on the strength of its electrostatic 914 Copier, introduced in 1960, the company's total operating revenue (net sales plus rental income) soared from $32 million in 1959 to $176 million in 1963. Until October 1961, Xerox held the electrostatic copying field entirely to itself. Then, American Photocopy Equipment Co. (Apeco) introduced an electrostatic office copier based on the Electrofax process, developed by RCA. Now, three other companies (SCM, Bruning, and Dennison) also offer machines using this process. In addition, such companies as Savin, Frantz Industries, Quik-Chek Electronics & Photo, Royal McBee, Old Town, and Olivetti expect to market copying machines based on the same process sometime this year. According to recent estimates by
Arthur D. Little, Inc., the sales and rentals of Electrofax machines and supplies will rise from $30 million in 1963 to $90 million in 1 9 6 5 - a gain of 200%. During the same period, the sales and rentals of Xerox's electrostatic copying equipment and supplies are expected to climb from $140 million to $250 million-a gain of 7 9 % . On the other hand, during the same period, the sales of another dry process, thermography, are expected to remain constant at $100 million a year. Wet
Methods
While the dry electrostatic processes are surging to new heights, the wet copying methods are losing ground. This is plainly evident, for example, in the recent sales figures of Apeco, whose business until a few years ago was almost entirely in the field of wet diffusion transfer copying. Apeco's net sales have slipped from $35 million in 1961 to $31 million in 1963, even though the company's sales of electrostatic machines and supplies (introduced in late 1961) have been increasing and reached about $11 million last year. The total sales of diffusion transfer copiers and supplies by all U.S. producers, says Arthur D. Little, will drop from $55 million in 1963 to $40 million in 1965. In the same period, the retail sales of copiers and supplies used in another wet process, the gelatin transfer process (Kodak's Verifax), are expected to decrease by $10 million. In many quarters, customers are developing mounting resistance to copiers that use "messy chemicals" (a term of withering scorn) and commit what is viewed as the unpardonable offense of turning out damp copies. Most office copying, of course, is done by secretaries, many of whom shudder at the thought of handling liquid chemicals, cleaning out chemical-encrusted machines, and fussing with moist papers. Hence, machines that use no liquid chemicals and produce copies described ecstatically in magazine advertisements as "bone dry" or "desert drv" have obvious appeal. More and more users today are demanding copies that are not only dry but are almost indistinguishable from the original. As one company executive says flatly, "Let's face it. The customer has become infinitely more sophisticated." When the new office copying ma-
chines came out in the early 1950's, the typical user was positively thrilled that the things worked at all. All he wanted was a copy that was legibleeven if only barely legible. Usually, he wasn't too concerned about the quality of the paper, the durability of the copy, and all the other niceties. Now, many users are insisting that the copies be on paper similar or identical to regular bond. They want beautifully sharp copies, and they want them to last essentially forever (what the trade calls "copies with archival quality"). In addition, more and more users are demanding that copying machines operate at high speed, be completely automatic, be as compact as possible, and almost never turn out "wastebasket copies" (resulting from wrong exposure or other faulty operation). And they are insisting that the copies cost no more than 5 cents each and preferably less. Of course, not all users make such lofty demands. An office that needs only a few copies a day, that is completely satisfied if the copies are less than sparkling, and that is unperturbed if the machine takes 50 seconds per copy instead of 5 obviously doesn't need the ultimate in office copiers. Even though many machines now on the market are relatively slow and awkward to use and produce inferior copies at comparatively high cost (although the machines themselves are cheap), they are entirely satisfactory for many users—particularly smallvolume users who cannot afford the more elaborate devices with all the alluring refinements. These less expensive machines are also attractive to the customer who wants a large number of copying units scattered at various locations throughout an office. In this way, he can avoid the sometimes exasperating delays caused by trotting documents and copies to and from a distant, centralized copying machine.
The sales of supplies, such as sensitized papers and processing chemicals, account for between 70 and 75% of the total sales of the office copying industry. At Apeco's Clayton Chemical Division, plastic bottles are filled with developer solution for diffusion transfer copying machines
Better Machines and Processes A major trend in recent years has been the concerted effort of many producers of office copying machines to overcome the specific, well-known shortcomings of their equipment. For example:
These machines at Apeco turn out large volumes of coated paper for the diffusion transfer process
• Many potential customers have complained that only the user who needs large numbers of copies can possibly afford the basic rental for a JULY
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Xerox 914 Copier. Also, they have argued, the 914 is too bulky. Last year, Xerox came out with the tabletop 813 Copier, a compact unit priced within the reach of the medium-volume user. • Some customers have vehemently objected to the fact that 3M's ThermoFax machines do not copy all colors and that the copies are made on flimsy paper. Last year, 3M introduced its Dual Spectrum process, which can readily handle all colors. And the copy paper, although treated, feels much like regular bond. • Some companies refused to buy a Kodak Verifax machine because it involved too much manual operation and required the pouring of chemicals. Last year, Kodak introduced its Verifax Cavalcade Copier, which operates more automatically than earlier Verifax machines and uses premixed solutions supplied in disposable plastic bottles (no pouring). In many other ways, office copying firms have made substantial improvements in their equipment. Their aim, obviously, is to offer the most efficient, attractive machines possible to the burgeoning, increasingly competitive copying market. The copying of documents photographically goes back to the earliest days of photography. In 1839 (the
same year that Jacques M. Daguerre, a theatrical scene painter in Paris, announced the first practical photographic process), Albrecht Breyer, a German medical student at the University of Liege in Belgium, was doing experiments on using silver halidecoated paper to copy pages from books. In 1842, Sir John Herschel, a British chemist and astronomer, developed the blueprint process. This method involves the light-induced reaction of ferric ammonium citrate and potassium ferricyanide in the presence of water to form an insoluble blue compound. The image is made permanent by washing away the unreacted chemicals. Although an enormous advance in its day, blueprinting has several drawbacks. The original has to be prepared on a transparent or translucent sheet. The sensitized paper responds only to ultraviolet light. The method is tedious and time-consuming. And it produces white-on-blue copies, which many users find objectionable because they are difficult to write on legibly. The first successful device developed in this country to copy existing documents (not merely specially prepared originals) was the Rectigraph machine. It was invented in the early 1900's by George C. Beidler,
a clerk in an abstract office in Oklahoma City who was primarily looking for an efficient way to copy legal documents. In 1906, he formed Rectigraph Co. in Oklahoma City to market the device and in 1909 moved the firm to Rochester, N.Y. Years later, the company was bought out by Haloid Co. (now Xerox Corp.). A similar copying machine was invented at the turn of the century in France by Rene Graffin, a professor at the Institut Catholique de Paris. Called the Photostat machine, it was first offered commercially in the U.S. in about 1910 by Photostat Corp. (now a subsidiary of Itek Corp.). Generally known as projection photographic copying machines, these devices consist of a large camera (to project right-reading images onto the silver halide-coated paper) and a processing unit. After the sensitized paper is exposed, it is developed, fixed, washed, and then dried—as in conventional photographic processing. The method has the advantage that it can enlarge or reduce images. However, it also has many shortcomings: • The machine is too expensive for most offices. Partly because it requires an expensive lens system, the equipment costs anywhere from $7500 to $14,240. • The method is usually slow (making a finished print may take 15 to 30 minutes or more, depending on the washing time). • Copies normally come out white on black (unless the newer directpositive papers are used). • The machine is fairly large and cumbersome. • An ample supply of running water is needed to wash the prints. • The operator has to be reasonably well skilled.
Between 1910 and the late 1930's, the only practical office copying devices were projection photographic copying machines, which were found in relatively few business offices. Most copying was done by typists. This is the typing department at Montgomery Ward 6- Co. in Kansas City, Mo., in 1913
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Office copying could only begin to make significant headway if essentially all of these obstacles were surmounted. New machines would have to be cheap, quick, compact. Also, they would have to require no running water, no special skill. Some progress was made in the late 1930's with the introduction of contact box printers, supplied by Hunter, Remington Rand, Apeco, and others. Simple machines containing no lens system, they sold for about $100 to $250. A copy was usually made by passing light through a onesided original in contact with a sheet
How the Major Office Copying Processes Work The principal office copying methods are divided into two broad categories—those that use silver halide (primarily silver chloride and silver bromide) and those that do not. In the silver halide category are the diffusion transfer, gelatin transfer, and stabilization processes. The non-silver halide methods include the diazo, thermographic, transfer electrostatic, and direct electrostatic processes. Diffusion Transfer Process The diffusion transfer process uses two different sheets of chemically treated paper. One is the negative sheet, which is coated with a gelatin emulsion containing silver halide and other materials and is sensitive to light. The other sheet is the positive, which is coated with a silver nucleating agent, usually in a gelatin layer, and is not sensitive to light.
light is reflected back to a negative from nonimage areas of original
unexposed silver halide, in the form of a complex, is diffused to a positive sheet and is converted there to metallic silver
undeveloped negative
original developed negative
positive
The original document is placed face down against the gelatin layer of the negative paper and is exposed to visible light by the reflex method. In this method, the light first passes through the sensitized paper, strikes the original, and is reflected back from the nonimage areas of the original onto the sensitized paper. The silver halide emulsion and the exposure time are properly chosen so that the light that goes through the emulsion directly has essentially no effect on it. Only in the areas exposed to both direct and reflected light (areas corresponding to the nonimage areas of the document) is the silver halide sufficiently altered, with the formation of a latent image. After the negative is exposed, it is separated from the original and placed face to face against a sheet of positive paper. The two are immersed in a solution containing a developer, such as methyl-p-aminophenol sulfate (Metol) and hydroquinone, and a silver halide solvent, such as sodium thiosulfate (hypo). The developer converts the silver halide in the latentimage areas of the negative to metallic silver. The silver halide solvent reacts with the unexposed silver halide (in the areas corresponding to the image of the original document) and converts it to a soluble complex. This silver halide complex is transferred by diffusion from the negative sheet to the positive sheet pressed against it. The positive sheet contains a nucleating agent that, in the presence of developer, permits the transferred silver halide to be converted to metallic silver. The nucleating agent most frequently used is colloidal silver. Other possible materials are silver sulfide, colloidal sulfur, and organic sulfur compounds. The two sheets are passed through rollers to bring them into close contact and to remove the excess solution. They are then peeled apart, usually by hand. The positive sheet,
containing a black-on-white image of the original document, is then allowed to dry for a few minutes in air. Normally, only one copy is made per negative sheet. However, some sensitized papers made in Europe allow several copies to be produced from a single negative. Gelatin Transfer Process (Verifax) The gelatin transfer method (Kodak's Verifax) uses a lightsensitive sheet called a matrix, which consists of paper coated with unhardened gelatin containing a variety of chemicals. These include silver halide, a tanning developer, and a colorforming compound. The matrix is exposed to the original image by reflex. The matrix is then immersed in an alkaline activator solution containing sodium carbonate. This solution also contains a gelatin softener that aids the later transfer operation. In the presence of the activator, the matrix swells, and the tanning developer, which may be a hydroquinone or catechol derivative, chemically reduces the silver halide to metallic silver in the light-exposed areas of the matrix. The tanning developer is itself oxidized, and its oxidized product crosslinks the gelatin, hardening it in the light-exposed areas. The rest of the gelatin (in the areas corresponding to the image areas of the original) remains unhardened. During development, some of the color-forming compound is oxidized and couples with its unoxidized form to produce an insoluble blue dye throughout the matrix. This dye can be transferred to another sheet only by the transfer of gelatin that has not been hardened and made insoluble. The excess activator solution is squeezed from the swollen matrix, which is pressed against a sheet of copy paper, usually treated with thiourea. Although copies can be made on ordinary untreated paper, the thiourea-treated paper provides a darker, more permanent image.
undeveloped matrix
... . „ . , , . light is reflected back to a negative from nonimage areas of original
original developed unhardened areas of dyecontaining gelatin are transferred to copy paper copy paper
As the matrix is squeezed against the copy paper, a thin layer of the soft, swollen gelatin is transferred to it. This transferred gelatin contains not only the blue dye but also unexposed silver halide, tanning developer, and a small amount of metallic silver. The dye contributes to the immediate color of the image on the copy paper. This dye, however, gradually fades within a few weeks. With treated copy paper, this fading is largely counterbalanced by the gradual conversion of the transferred silver halide to metallic silver and silver sulfide. After the matrix and copy sheet are squeezed together, they are separated by hand, yielding the finished, slightly damp copy. If desired, the same matrix, after reimmersion in the activator solution, can be used to make five or six JULY
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additional copies. An experienced operator, however, can make as many as 10 copies from a single matrix.
Stabilization Process The stabilization process is designed to eliminate the need for removing unreacted silver halide from conventional photographic paper after it has been exposed and developed. In ordinary photographic processing, the unexposed halide is removed by reacting it with a solubilizing agent, such as sodium thiosulfate, and then washing. In the stabilization process, no attempt is made to remove the silver halide, and, therefore, no washing is required.
light is reflected back to a negative from nonimage areas of original
undeveloped negative
original negative is developed and then treated to make the remaining silver halide essentially insensitive to light
developed negative
In this process, the sensitized paper, coated with silver halide, is exposed by reflex to the document. The sensitized paper is then immersed in a conventional developer solution, which converts the exposed silver halide to metallic silver in the areas corresponding to the nonimage areas of the document. In some systems, the developer is already present in the paper, and the solution merely activates the developer. The paper then goes to the stabilizer bath. The stabilizing compound most frequently used is ammonium thiocyanate. Some methods use thiourea or a combination of sodium thiosulfate and sodium bisulfite. These compounds form complexes with the unexposed silver halide, making it relatively insensitive to light. After leaving the stabilizer bath, the paper is squeezed to remove the excess solution. Finally, the damp sheet is dried in air. Diazo Process The diazo process depends on the fact that many diazonium compounds react with couplers to form azo dyes. The process also depends on the fact that ultraviolet light can decompose these diazonium compounds before they are coupled and thus can prevent the formation of a dye.
ultraviolet light decomposes a diazonium compound on diazo paper in nonimage areas
original
where the diazonium compound has been destroyed, no color reaction takes place. In the moist diazo process, the sensitized paper contains only the diazonium compound. After the paper is exposed to ultraviolet, it is treated with an alkaline solution containing the coupler. The reaction forms a dye in the image areas.
Thermographic Process 3M's Thermo-Fax process, the most popular of the thermographic processes, uses treated paper containing compounds that form a colored substance when heated. The reaction usually involves a ferric compound, such as ferric stearate or ferric myristate, and a phenolic compound, such as pyrogallic acid, gallic acid, or tannic acid. These materials are held in a binder, such as polyvinyl butyral. A waxy ferric compound is used so that the reaction does not take place until the material has melted. Otherwise, the reactants would form a colored product as soon as they were mixed.
in the Thermo-Fax process, heat generated in the infrared-absorbing image areas is transferred to heatsensitive paper, forming a colored compound
heat-sensitive paper
original
The heat-sensitive paper is placed in contact with the original, with the treated side face up over the side to be copied. Infrared radiation is allowed to pass through the treated paper and strike the original. The infrared is not absorbed by the treated paper and, therefore, does not affect it directly. However, the infrared that strikes the printed areas of the original is absorbed (provided the ink contains carbon black or a metallic compound). The heat that, as a result, is generated in the printed areas is transmitted to the heat-sensitive paper. This causes the treated paper to form a colored compound in the corresponding areas, thus producing a copy of the original. The Thermo-Fax paper that was first made by 3M was entirely different. It consisted of a black noninfrared-absorbing sheet coated with a crystalline wax (camauba wax or stearates) that gave the paper an opaque, whitish surface. The image was formed not by a chemical change but by a purely physical change—the melting of the wax in the image areas, which converted it to a translucent form. This allowed the black backing to show through. 3M, after making this paper for about two years, discontinued it because the image formed was not sufficiently sharp, the paper was subject to pressure-marking, and many users complained that it had an objectionable feel.
diazo paper
Transfer Electrostatic Process (Xerox) diazo paper is treated so that a coupler forms a dye with the undecomposed diazonium compound
treated diazo paper
First, the original document, either on a transparent or translucent sheet, is placed face up over the sensitized paper. This sensitized paper contains a diazonium compound, such as a derivative of N,N-diethyl-p-phenylenediamine. In the dry diazo process, the sensitized sheet also contains a coupler, such as the sodium salt of 2,3-dihydroxynaphthalene-6-sulfonic acid. In addition, it contains an acid that prevents the premature reaction of the diazonium compound and the coupler. After the paper is exposed to ultraviolet light passing through the original, it is treated with ammonia. This neutralizes the acid and allows the remaining diazonium compound to combine with the coupler and form a dye in the image areas. In the nonimage areas,
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Xerox's transfer electrostatic process makes use of the photoconducting property of amorphous selenium. This material will hold an electrostatic charge in the dark but will allow it to be dissipated where exposed to light. First, a selenium-coated drum is given a uniform, positive original light dissipates positive electrostatic charge on photoconductor surface in nonimage areas
powder adheres to the remaining charged areas
photoconductor on a metal support photoconductor on a metal support untreated copy paper
powder is transferred to copy paper and then fused
photoconductor on a metal support
electrostatic charge. This is done by passing it under a series of corona-discharge wires in the dark. The drum is then exposed to the document image projected through a lens system. Where the light strikes the drum, the charge is dissipated by flowing off to the conducting aluminum support and then to ground. The electrostatic charge remains, however, in the image areas. Toner powder mixed with a carrier is then cascaded across the surface of the drum. This powder, consisting of a pigmented fusible resin or plastic, is negatively charged and clings by electrostatic attraction to the positively charged areas of the drum. This forms a powder image of the original. Next, a sheet of ordinary untreated paper is placed over the powder image and given a positive electrostatic charge by corona-discharge wires. As a result, most of the negatively charged powder on the drum is transferred to the paper. Finally, the paper is heated to about 200° C. to melt the thermoplastic powder and bond it to the paper. The selenium drum is automatically wiped to remove the remaining toner and is immediately ready for re-use. Direct Electrostatic Process (Electrofax) In principle, the direct electrostatic process is very similar to the transfer electrostatic process. The chief distinction is that, in the direct method, the electrostatic image is formed directly on the final copy paper and, therefore, does not have to be transferred to it. All commercial papers used in the Electrofax process are coated with zinc oxide, which acts as the photoconducting material. The finely divided zinc oxide is held on the paper by an insulating binder, such as silicone resin, polystyrene, or butadiene copolymers. In almost all cases, the coating also contains a combination of dyes that sensitize the zinc oxide to visible light. original light dissipates negative electrostatic charge on coated paper in nonimage areas with dry development, a powder adheres to the remaining charged areas and is then fused; with liquid development, a pigment suspended in a liquid adheres to the charged areas and liquid is removed
photoconductorcoated paper
photoconductorcoated paper
The coated paper is first given a negative charge in the dark by corona discharge. It is then exposed to the image projected through a lens system. Light from the nonimage areas of the document causes the charge on the paper to be dissipated in the corresponding areas. This leaves on the paper an electrostatic pattern that duplicates the image of the original. Either dry development or liquid development is then used to produce the visible image. In the dry method, the developer, consisting of a mixture of pigmented resin powder and iron particles, is applied to the paper by means of a so-called magnetic brush (the developer mixture held on a magnet). As this brush moves across the paper, the positively charged resin powder adheres to the negatively charged areas of the paper, while the iron particles are retained on the magnet. The paper is then heated for a few seconds to fuse the resin powder to it. With liquid development, use is made of pigment particles suspended in an organic liquid. The developer is applied to the paper either by dipping the paper in it or by spraying it on. The suspended pigment particles cling to the charged areas of the paper by electrostatic attraction and are held to it permanently, usually by a resin binder. After most of the liquid has flowed off the paper, the remainder is ordinarily removed by blowing warm air across it.
of silver chloride photographic paper, which could be handled safely in subdued light. Two-sided originals could also be copied, but this required more elaborate processing. The method involved the laborious handling of photographic papers and chemical solutions and also lengthy washing. Making a single print took at least half an hour. Diffusion Transfer Process The real breakthrough came with the commercial introduction in Europe in the late 1940's of the diffusion transfer process (also known as the diffusion transfer reversal process, the silver transfer process, and the silversalt diffusion process). The method, although based on the use of silver halide, is appreciably faster and easier to operate than ordinary photographic processing. In the diffusion transfer method, silver halide in the unexposed areas (the image areas) of a negative sheet is solubilized and allowed to diffuse to a positive sheet. There, the transferred silver halide is converted to metallic silver, thus forming the desired image. The result is a high-quality, black-onwhite copy, made in a minute or less. Pioneering work on the diffusion transfer process was done in Belgium, Germany, and the U.S. In the late 1930's, Andre Rott, a chemist in the laboratories of Gevaert Photo-Producten, N.V., in Mortsel (Antwerp), Belgium, developed the basic principles of this method (U.S. Patent 2,352,014, issued June 20, 1944). His first patents, assigned to Gevaert, were filed in 1939. Independently at about the same time, Dr. Edith Weyde, a chemist in the Agfa laboratories of I. G. Farbenindustrie in Leverkusen, Germany, was working on the same process. She applied for patents in 1941. Among her prime contributions was the development of diffusion transfer papers that gave denser images. In the early 1940's, Dr. Edwin H. Land in the U.S. was also doing work on the diffusion transfer process. Dr. Land, who later gained fame as the inventor of the Polaroid-Land camera, was chiefly interested in using diffusion transfer in popular photography, rather than office copying. The diffusion transfer principle is, in fact, the basis of Polaroid-Land photographic film. For the diffusion transfer method to JULY
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Producers of office copying machines and supplies are stepping up their research on improved products. Fred H. Volhardt, a chemist at Apeco, studies new coatings for diffusion transfer papers
At Kodak, Dr. Henry C. Yutzy (left) and Edward C. Yackel, coinventors of the gelatin transfer process (Verifax), discuss the new Verifax Cavalcade Copier
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become practical in office copying, an efficient machine had to be developed to operate it. Such a machine was invented early in 1949 by Dr. Walter Eisbein of Trikop, G.m.b.H., in Stuttgart, Germany. Using Dr. Eisbein's invention, Agfa in late 1949 introduced its first diffusion transfer unit, the Blitzkopie or Copyrapid. The Eisbein device was first imported into the U.S. by Remington Rand in 1952 and sold as the Transcopy machine. The first U.S. company to make diffusion transfer copiers was Apeco, which introduced its machine in June 1952. The Apeco unit, called the Autostat, found a ready market, and the company has dominated the U.S. diffusion transfer field ever since. Although other American firms obtained licenses under the Eisbein patent (U.S. Patent 2,657,618, issued Nov. 3, 1953), Apeco, regarding the patent as invalid, made its machines without an Eisbein license. In 1955, Copease Mfg. Co., which held the U.S. rights to the Eisbein patent, sued Apeco for patent infringement. After a lengthy legal wrangle, Apeco settled the case in 1962 by paying Copease $5.5 million and at the same time obtaining the U.S. rights to the Eisbein invention. Since then, Apeco has licensed 11 U.S. companies making diffusion transfer machines. As has been true for years, a greater number of U.S. companies sell diffusion transfer machines than sell any other type of office copying device. Today, some two dozen U.S. firms offer this equipment, either made domestically or imported. In addition to Apeco, the leading suppliers are Anken, Speed-O-Print Business Machines, A. B. Dick, SCM, and General Aniline & Film. To make diffusion transfer more competitive with other processes, some companies are now offering cheaper sensitized papers. Normally, for a single diffusion transfer copy, the cost of the paper (one negative and one positive sheet) has been about 8.5 cents. In recent months, however, Peerless Photo Products, A. B. Dick, and others have lowered their price to 5 cents. This has resulted, in part, from the development of a new type of treated positive paper made directly at the paper mill. Usually, positive paper is made by first producing ordinary untreated paper at the mill and then shipping it to another location to be coated with a gelatin layer containing the required silver nucleat-
ing agent. This two-step operation, of course, adds to the cost. Moreover, the new paper, although treated with a nucleating agent, has no gelatin coating. Thus, when later used, the paper retains much less moisture as it comes out of the diffusion transfer machine. Copies dry in a minute, compared to about three minutes for conventional gelatincoated paper. On the other hand, the copy quality is not as good as with conventional paper (blacks are less dense). To attract the customer who dreads the idea of messing with liquid chemicals, many companies are now offering diffusion transfer machines that use premixed solutions in disposable cartridges. As a special feature of many of these newer machines, the solution is returned to the cartridge when not in use, rather than being left in an open tray. Thus, the solution deteriorates less rapidly through attack by carbon dioxide and oxygen in the air. Gelatin Transfer Process In early 1953, Eastman Kodak entered the office copying market with its gelatin transfer process. Also known as the dye transfer method, this is Kodak's Verifax process. Offered solely by Kodak, it involves an intricate series of chemical reactions using gelatin, silver halide, a dye former, a tanning developer, and other compounds. The gelatin transfer method was invented in the late 1940's by two chemists, Dr. Henry C. Yutzy and Edward C. Yackel, working in Kodak's emulsion research laboratory in Rochester, N.Y. In the early days, their process (U.S. Patent 2,596,756, issued May 13, 1952) was known informally around the Kodak laboratories as the 2-Y process (for Yutzy and Yackel). The gelatin transfer method found immediate and widespread acceptance. Its major advantage over the diffusion transfer process is its ability to make as many as 10 copies from a single photosensitive sheet. On the other hand, like the diffusion transfer process, it requires the use of wet chemicals. Between 1955 and 1961, the sales of machines and supplies for the gelatin transfer process were the second largest in the office copying industry (3M's Thermo-Fax process was num-
All Office Copying Processes Have Their Mixture of Advantages and Disadvantages DIFFUSION TRANSFER PROCESS Advantages
• • • •
produces sharp, high-contrast copies can copy all colors machines are compact and relatively inexpensive equipment requires comparatively little maintenance
• involves the handling of ammonia or an alkaline liquid, unless the thermal diazo process is used • does not copy some blues and purples and other colors transparent to ultraviolet light THERMOGRAPHIC PROCESSES Advantages
Disadvantages
• uses wet chemicals •usually involves a relatively large amount of manual operation, although newer machines are fairly automatic • copies come out damp and must be dried •usually the cost per copy is relatively high GELATIN TRANSFER PROCESS (VERIFAX) Advantages
• can make a number of copies (usually up to seven) from a single matrix • if several copies are produced from a single matrix, the cost per copy is low • can copy all colors Disadvantages
• uses wet chemicals • usually requires a good deal of manual operation, although newer machines are more automatic • copies usually come out damp and must be dried • cost of a single copy is high STABILIZATION PROCESS Advantages
• requires only one type of coated paper • can copy all colors • reproduces photographs well Disadvantages
• requires wet chemicals • first copy is white on black, unless direct-positive papers are used •copies may gradually deteriorate through the formation of dark brown stains of silver sulfide DIAZO PROCESS
• no liquid chemicals needed • copies are made easily and rapidly • equipment requires little maintenance Disadvantages
•will only copy inks that absorb infrared radiation—that is, inks containing carbon black or a metallic compound • copies made on treated paper will usually darken if exposed to heat • in many cases, copies are made on lightweight paper that becomes brittle with age TRANSFER ELECTROSTATIC PROCESS (XEROX) Advantages
• uses no liquid chemicals • can copy all colors •copies are made on ordinary untreated paper and are permanent • excellent reproduction of printed type Disadvantages
• machine is too expensive for the low-volume user • does a poor job of copying photographs and large solid areas • complex machine requires more than the usual amount of maintenance •uses a selenium-coated drum that must be replaced periodically (normally, after about every 40,000 to 50,000 copies) DIRECT ELECTROSTATIC PROCESS (ELECTROFAX) Advantages
• requires no liquid chemicals, although some machines use a liquid developer • can copy all colors • excellent reproduction of all printed matter, including photographs and large solid areas • copies are made rapidly and are permanent
Advantages
• lowest cost per copy of any office copying method • can produce copies in any one of a variety of colors • copies are permanent Disadvantages
• normally does not copy opaque originals or originals printed on both sides
Disadvantages
• copies must be made on coated paper • because of coating, the paper may be heavier than ordinary paper • copies can be marred by scratching with metals • if a liquid developer is used, the copies may smear for a short tirr" after they come out of the machine
Dr. Carl S. Miller and the Invention of Thermography
,£?*"&*$
ber one). However, since then, with the rapid growth of Xerox's electrostatic process, the gelatin transfer method has slipped into third place. Over the years, Kodak has steadily improved its Verifax equipment. For example, the new Verifax Cavalcade, introduced in September 1963, is not only more automatic than earlier units but holds enough activator solution to make as many as 2000 copies. Previous machines, using a different activator, could hold only enough solution to make about 200 copies. Kodak's new Readyprint Copier, also introduced last September, is the company's fastest wet copying machine yet. Using an accelerated version of the gelatin transfer process, it can make a copy in only 25 seconds, compared to 40 to 60 seconds normally required. Unlike other Kodak copying machines, however, the Readyprint is designed to make only one copy per matrix. 124
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Stabilization
The discovery of the basic principle of 3M's thermographic process, Thermo-Fax, like the discovery of Xerox's electrostatic process, was the work of art independent inventor. Both methods, however, required years of research and development by large research organizations before they could be launched commercially. The thermographic process was conceived by Dr. Carl S. Miller, a physical chemist who is now senior research specialist in 3M's graphic arts department. He did his first work on the process while still a graduate student at the University of Minnesota. In gathering reference data for his graduate thesis on polarography, he spent long hours searching the chemical literature. The job of recording key information from lengthy scientific reports wasn't too bad. However, the need to copy dozens upon dozens of abstracts verbatim in longhand became increasingly tedious. If only there were some way, he thought, to copy tnis material automatically by a simple chemical process! In the spring of 1940, a few months before he received his Ph.D., he hit upon the idea of using infrared radiation as a means of copying. He reasoned that, if a sheet coated with heat-sensitive, color-forming substances were placed in contact with a document and the two sheets were exposed to infrared radiation, a practical copying method might result. The radiation would be absorbed and converted to heat only in the infrared-absorbing areas (the image areas) of the document. This heat, in turn, would be absorbed by the heat-sensitive sheet, thus producing a color-forming reaction that would create a copy of the original document. Dr. Miller did his first experiments on the process in the workshop of his campus rooming house. He prepared a heat-sensitive sheet by dipping a piece of cellophane from a candy box in a colorless solution of thiourea and lead acetate. He then placed the dried sheet over a piece of printed matter—actually, the return-ad dress envelope from a magazine subscription department ("The letters were big and bold/' he explains). He attached the two to a makeshift cardboard cylinder to ensure good contact between the two
Process
Still another silver halide process is the stabilization method (also known as quick stabilization). In this process, the unreacted silver halide that remains on the photographic paper after it is exposed and developed is not removed to make the print permanent. Instead, the halide is treated with a complexing agent that renders it resistant to light-induced decomposition and darkening. This stabilization reaction replaces two steps in ordinary photographic processing—the conventional fixing step and the especially time-consuming operation of washing. As a result, a print can be obtained in 10 to 15 seconds, instead of the usual 30 minutes or more. In the U.S., the stabilization process is used relatively little in office copying. It does find use, however, in coinoperated copying machines (made by Documat, Inc., and Victoreen Instru-
ment Co.) installed in such places as public libraries, hotels, air terminals, and court-record rooms. It is definitely much more popular in Europe and South America. The stabilization method has been under development for many years. As far back as 1893, Dr. A. Bogisch, a German photographic chemist, studied the use of thiourea to stabilize developed emulsions. In the late 1940's, Mr. Yackel (co-inventor of the Verifax process), Dr. Harold D. Russell, and others at Kodak worked out major improvements in stabilization methods. In 1950, Steven Levinos (now at General Aniline & Film) and co-workers at the Army Signal Corps Laboratories in Fort Monmouth, N.J., made further advances in stabilization processing— for example, by developing better ways to increase the stability of thiourea-treated images to heat and high humidity. The Signal Corps was primarily interested in the stabilization
sheets. He then proceeded to expose the sheets to infrared radiation from an ordinary 1000-watt light bulb. After brief exposure, the two sheets were peeled apart, and there it was—the transferred image. The image wasn't perfect. The edges of the letters were fuzzy. But the process worked. In the presence of heat, the thiourea had reacted with the lead acetate to produce black lead sulfide. For several weeks, Dr. Miller continued his experiments, first at his rooming house and then in the university chemistry laboratory. He found, for example, that he obtained sharper images if, instead of using radiation from an ordinary light bulb, he used sunlight focused by a magnifying glass. He also found that paper treated with lead acetate really wasn't too good after all. On standing, it may gradually discolor by reacting with sulfur compounds in the air. Research at 3M In July 1940, Dr. Miller joined the research laboratories of Minnesota Mining & Mfg. Although at the time the U.S. had not yet entered World War II, the company was actively engaged in defense work. Dr. Miller was given the job of developing pigments for camouflage paints. For the next four years, he did research primarily on pigments. However, he did keep up a sideline interest in thermographic copying and occasionally worked on it in the 3M laboratories. "Most of my efforts," he says, "consisted of mulling over the idea—what the boys in the lab nowadays call 'noodling it.' The whole thing was more or less a hobby with me—rather like collecting butterflies. In fact, I seriously questioned whether the process would ever have any commercial value at all." Early in 1944, Dr. Miller built a crude model of a thermographic copying machine and showed it to Dr. Harry N. Stephens, research director of 3M. The machine produced images only 2 inches square. However, Dr. Stephens and other 3M executives were sufficiently impressed so that in May 1944 the thermographic process became a formal research project, then known as Thermoprinting. Dr. Miller and
process as a quick way to reproduce photographs—without using large amounts of water (often unobtainable under military conditions). Although attractive from some points of view, the stabilization process has a number of drawbacks. It is a wet process that makes damp copies. Moreover, the first copy is usually white on black (this copy, however, can be used to make subsequent copies that are black on white). Also, the copies lack real pennanence. In time, the silver halide complexes may decompose, with the formation of dark brown stains of silver sulfide. However, if the user only wants the copy to last two or three years, this is ordinarily no great hazard. Diazo Process The diazo process, although used mainly in copying engineering and architectural drawings, is also finding
one assistant began working on the project full time. Many problems lay ahead—developing suitable copy paper, creating a proper infrared source, perfecting the machine. By 1946, Dr. Miller and his staff (now enlarged to include two assistants) developed a heat-sensitive paper that uses the reaction of a ferric compound and a phenolic compound to form the colored image. This reaction, used for centuries in tanning leather and making inks, is the basis of most of today's Thermo-Fax papers. A major technical hurdle was the job of finding an effective way to irradiate the heat-sensitive paper. Initially, Dr. Miller assumed that the infrared source would have to expose the sheet all at once. But this would require a prohibitively large and powerful radiation source. Eventually, he developed the idea of rotating the document and the sensitized sheet in front of a narrow beam of infrared radiation (sometimes called "the hot line"), focused by an elliptical reflector. Thus, a much smaller, more economical lamp could be used. This method, however, would require a 2000-watt lamp and one with a straight filament. No such lamp was on the market. Dr. Miller and an assistant spent six months making their first successful lamp. Then, in mid-1945, they approached General Electric to see whether the company would produce these bulbs commercially. At first, GE scientists raised serious doubts as to whether such a bulb could be made at all—until Dr. Miller explained that he and an assistant had already made one, which he promptly pulled out of his briefcase. GE agreed to take up the challenge. Four months later, it delivered to Dr. Miller what he describes as "two beauties." In 1950, after years of research and development, the first commercial Thermo-Fax machine was ready. It was purchased by the Central Intelligence Agency in Washington, D.C. The first shipments to nongovernment users went to Dow Chemical and the New York Public Library. The thermographic process caught on rapidly. In time, Thermo-Fax copying machines and papers became the fastest growing product line in 3M's entire history.
an important place in office copying. The method (also known as the whiteprint or diazotype process) has the prime advantage of being the cheapest office copying method available. Diazo machines make copies for 1 cent each, compared to at least 4 or 5 cents each for almost all other methods. The great limitation of conventional diazo machines, however, is that the original document must be on a transparent or translucent sheet and cannot be printed on both sides. The reason is that, in ordinary diazo copying, the ultraviolet light must first pass through the original before striking the sensitized paper—a method known as printthrough exposure. Other copying processes, on the other hand, normally use either reflex exposure or projection exposure— neither of which requires that the radiation be transmitted through the original. In the reflex method, the
light first passes through the sensitized material and is then reflected off one side of the original onto the sensitized surface. In the projection method, the light is first reflected off one side of the original and is then focused by an optical system onto the sensitized material. Thus, in both the reflex and projection methods, any printing on the opposite side of the original has no effect. With the diazo process, reflex exposure normally cannot be used because the ultraviolet light passing directly through conventional diazo paper would destroy all of the lightsensitive diazonium compound. Projection exposure, on the other hand, could be used, but this would be difficult and expensive because of the quartz optics required by the ultraviolet. The limitations on the types of originals that conventional diazo copying machines can accept have been the JULY
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chief reasons for restricting the use of these machines in office copying. The demand for diazo equipment in office copying is getting a marked boost, however, as more and more companies are deliberately placing their business forms on translucent paper so they can be readily copied by these machines. Also promoting the use of diazo machines has been the recent development of new types of paper for office forms and stationery that look almost like ordinary paper but are translucent enough to be handled by the diazo process. Far from new, diazo copying was investigated as far back as 1884. The first really successful process was developed in the early 1920's by Dr. Gustav Kogel, a German professor of photochemistry and a former Benedictine monk. His dry diazo method (U.S. Patent 1,444,469, issued Feb. 6, 1923) was first offered commercially in Germany in 1924 by Kalle & Co., a part of I. G. Farbenindustrie. To market its diazo machines and papers in the U.S., Kalle in 1933 set up a wholly owned subsidiary, Ozalid ("diazo" spelled backwards with an "1" added). When I. G. Farbenindustrie reorganized its U.S. operations in 1940, Ozalid became a part of General Aniline & Film. Also in the U.S., Charles Bruning Co. entered the diazo field in 1929 with a moist process developed by Dr. Karel van der Grinten and Dr. Lodewijk van der Grinten in the Netherlands (U.S. Patent 1,841,653, issued Jan. 19, 1932, and others). Today, the leading U.S. suppliers of diazo equipment and papers are GAF, Bruning, Ditto, Tecnifax, and Frederick Post. Until recently, commercial diazo machines were divided into two broad categories—those using ammonia gas as the required alkaline agent (dry diazo machines) and those using an alkaline solution containing a dye coupler (moist diazo machines). GAF, Bruning, Ditto, Tecnifax, Frederick Post, Rotolite, and others make the dry machines. Bruning makes equipment for the moist process, as will Frederick Post starting next month. Now, a new category has been added—the thermal diazo process. Commercial development of this method, which has been in research since the mid-1940 , s, is a major advance in the diazo field. In essence, the process is designed to meet the ob-
A secretary uses a 3M Thermo-Fax office copying machine to prepare monthly bills from ledger cards
In a Bruning lab, a technician tests various diazo coatings
The diazo process is being used increasingly in office copying. However, its principal use, illustrated here, is in the copying of engineering drawings
JULY
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1964
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OUR DI-PERBENZOATE SAVES CATALYST MONEY AND IMPROVES PRODUCTS In Premix Prepreg Preform
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jections of users who refuse to fuss with an alkaline solution and simply will not put up with the odor of ammonia. The thermal diazo process requires no alkaline solution, no ammonia g a s in fact, no outside chemicals at all. All of the required chemicals are in the sensitized paper. After the paper is exposed to the image, it is heated. In the method used by such companies as GAF, Bruning, Dietzgen, and Nashua, the heat decomposes a compound that releases the required alkali. Among the possible heat-sensitive materials are urea, thiourea, ethanolamine complexes, and other alkali-releasing compounds. In an alternate method, the heat does not decompose an alkali-releasing compound but breaks down a physical barrier, permitting an alkali to come in contact with the dye-forming components. Entirely different mechanisms for producing azo dye images on heating are also being studied. General Aniline & Film introduced its first commercial thermal diazo copier, the Ozalid 150, in May. Frederick Post will begin marketing a thermal diazo machine late this year. Other companies, such as Bruning, Dietzgen, Nashua, and Rotolite, are also working on thermal diazo machines. An inherent problem in all types of diazo processes is their relative insensitivity to light. All of the energy needed to decompose the diazonium compound in the nonimage areas must come from the light, mainly ultraviolet. Thus, if the process is to be reasonably fast, a high-intensity radiation source is required. By contrast, silver halide processes need relatively little light—just enough to form the latent image. Most of the energy for producing the final silver image comes from the action of the chemical developer. As long as the light produces a microscopic speck of silver in a silver halide grain, the developer will form metallic silver throughout the grain—a multiplication effect (or increase in quantum yield) that may reach a million or more. Methods that could raise the quantum yield of diazo materials beyond the present level of less than one would, of course, be highly desirable. In recent years, much research has been aimed at producing this higher yield, but with uniformly discouraging results. Says one research director, "Unless a radical change in diazo
Recordok Corp., a Kodak subsidiary, recently introduced this thermographic copier based on the Ektafax process. From a single intermediate sheet, it can make 10 or more copies on ordinary paper
chemistry is discovered, such an improvement will not be achieved." Thermographic
Processes
A significant advance in office copying came in January 1950, when Minnesota Mining & Mfg. commercially launched its thermographic process, Thermo-Fax. Unlike silver halide processes, this method is completely dry. Unlike the usual diazo process, it copies two-sided, opaque originals. And it is extremely fast (a copy can be made in five to six seconds). In 1955, 3M, which previously had made its Thermo-Fax machines only in the form of large console models, introduced its first table-top model, the Secretary. With this machine and other compact units that followed, the Thermo-Fax process rocketed in popularity. In fact, more Thermo-Fax machines have been sold than machines for any other office copying process. As one of its strongest appeals, a Thermo-Fax machine uses no "messy chemicals." Although some people grumble about the quality of the copies, many users are absolutely sold on the machine's speed, simplicity, compactness, and economy. The Thermo-Fax process was invented by a physical chemist, Dr. Carl
S. Miller, shortly before he joined the 3M laboratories in 1940. The method (U.S. Patent 2,740,896, issued April 3, 1956) uses the heat generated in the infrared-absorbing image areas of a document to induce a color-forming reaction on treated paper. A broad range of compounds are being used today in 3M's varied selection of heat-sensitive papers (U.S. Patents 2,663,654-7, issued Dec. 22, 1953, and others). Although the most widely used Thermo-Fax papers are buff-colored, they now come in a range of colors, including white. The white paper, introduced in 1961, is not only more attractive to many users but does not darken rapidly until heated to 102° C , compared to 79° C. for buff paper. As a result, the white paper is less apt to become discolored by being left on a window sill in the sun or placed near a radiator. A great point of vulnerability of the Thermo-Fax process (what one competitor dramatically calls the process's "Achilles' heel") is its inability to copy colored inks that do not absorb infrared, such as those used in many ballpoint pens. Although this is only occasionally a serious problem, many users find it disconcerting when a Thermo-Fax copy of a letter, for example, comes out with everything on it but the signature. To solve this problem, 3M in October 1963 began marketing a copying machine based on its Dual Spectrum process, which copies all colors. The method, involving exposure by light and development by heat, uses a tissue-like intermediate sheet coated with a material that is decomposed by visible light. The intermediate sheet is first exposed to the image by reflex. This leaves on the sheet a pattern of undecomposed material corresponding to the image. The intermediate sheet is then placed in contact with a chemically treated copy sheet. When the two are heated to about 100° C , the compound on the copy paper reacts with the undecomposed compound on the intermediate to produce on the copy sheet a stable colored material, forming the image. Apart from the fact that the Dual Spectrum process copies all colors, it has the further advantage of making copies on paper that in later storage is not affected by heat. The copies, therefore, are more permanent than those on Thermo-Fax paper. To satisfy the customer who insists that his copies be made on ordinary
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untreated paper, 3M last February introduced its Copy-Mite machine. Operated together with a Thermo-Fax machine, it uses a heat-sensitive, tissue-like intermediate sheet coated with a relatively low-melting waxy material containing a noninfrared-absorbing dye. When the intermediate and the original are exposed to infrared radiation by reflex in the Thermo-Fax machine, the heat generated in the image areas of the original softens the low-melting material in the corresponding areas of the intermediate. The intermediate and a sheet of ordinary paper are then pressed together without further heating in the Copy-Mite unit, causing part of the softened coating to be transferred to the copy paper. As many as 10 copies can be made from a single intermediate. A closely related method is the Masterfax process, which Ditto began marketing in September 1959. This process (U.S. Patents 3,122,997-8, issued March 3, 1964) uses an intermediate sheet coated with a mixture of natural or synthetic waxes containing azo dyes or other dyes. The standard intermediate sheet makes only one copy. However, special masters, for use in duplicating, can make as many as 50 to 125 copies. A similar process is used in the Drycopy machines made by Commodore Business Machines and the Dryfax units made by ABM Dryfax Corp. Early next year, Speed-O-Print plans to introduce a similar copying system called Prestofax. Eastman Kodak, which previously confined itself solely to making wetprocess copiers, recently moved into the dry copying field with its Ektafax thermographic process. Recordak Corp., a Kodak subsidiary, began offering Ektafax machines commercially last month. For the time being, they are being used together with ThermoFax or other thermographic copiers made by other companies. Within a year, however, Recordak expects to have on the market a combined machine that includes both a thermographic exposure unit and an Ektafax transfer machine. The Ektafax process uses an intermediate sheet coated with a polymer impregnated with a noninfrared-absorbing dye. This sheet and the original are exposed to infrared radiation in a thermographic copier, where the polymer is chemically modified by heat in the image areas. The inter-
mediate sheet then goes to the Ektafax transfer unit, where it is pressed against a piece of copy paper. Under the influence of heat and pressure, some of the dye-impregnated coating in the image areas is transferred to the copy paper. A single intermediate can make 10 or more copies. In addition to its conventional Ektafax intermediate sheet, which makes multiple copies only from a single original, Recordak is also offering a special sheet that has the extraordinary ability to rejuvenate itself. Called the Miracle Master E, a single sheet of this material can be used to make a copy of one original and then only a few minutes later make a copy of an entirely different original—a process that can be repeated 10 times or more. The Ektafax process, like a number of other thermographic processes, makes copies on ordinary paper. This ability, as well as the ability to make copies rapidly and at relatively low cost, is likely to give marked impetus to the new techniques in thermography.
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