INDC;STRIAL ALIrDEXGINEERING CHEMISTRY
July, 1929
nitrocellulose films which retain their original adhesion, whereas nitrocellulose-resin films lose part of their adhesiveness after air-drying for a month. I n using ethyl abietate in nitrocellulose lacquers it has been found best to substitute it for both the plasticizers and the gum (or resin) now used, rather than for either alone. By so doing, lacquers are obtained which have a better heat resistance but not a better light resistance. Ethyl abietate is of value in interior, furniture, and wood lacquers, as well as lacquer undercoats. I n ethyl abietate a natural resin has been changed in chemical composition in such a way that, while it still retains its primary resin characteristics and imparts to the film gloss, depth, body, and adhesion, as a resin should, it has ceased to
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be incompatible with nitrocellulose and has come to have actually a latent solvent action on nitrocellulose. Conclusion
Every chemist mho has formulated lacquers will recognize in some of his own formulas the steps taken t o insure a homogeneous film using nitrocellulose with a resin not entirely compatible therewith, and will appreciate, the simplification of formulas made possible by using a resin which not only is soluble in nitrocellulose solvents but is in itself a latent nitrocellulose solvent. Literature Cited ( 1 ) Johnston, U S P a t e n t 1,682,280 (1925)
Some Aspects of Chemical Patent Searches’ Frederick H. Untiedtz XAIIONAL PRESSBUILDING, WASHINGTON, D. C
OOK before you leap” has its chemical counterpart in “Search before you research.” Patent searches are now well recognized as essential to any research program having in view the development of new processes or new materials. The value of patent protection in the creation of a non-competitive industry is now so fully understood and appreciated that the strength and ability of a corporation to stay in business is sometimes best estimated by the patents it o m s . It is believed that a short description of the functions of the various types of patent searches commonly made will be of interest to the chemist whose contact with patents and patent lawyers may be only to tell the attorney what his invention is, how it differsfrom some prior invention, and t o sign papers. The Patent Ofice has arranged all the United States patents into classes and subclasses. The classification represents years of study and makes it possible for one familiar with the system to locate patents pertinent to an invention with a minimum of time and effort. For example, class 260 covers carbon compounds and in its various subclasses all of the art of making definite organic compounds, such as dyes, resins, alcohols, organic acids, etc., is to be found. Class 23 embraces inorganic compounds and processes of making them. Here one finds, in the appropriate subclasses, processes of making ammonia, sulfuric acid, salts of sulfur, inorganic nitrates, carbonates, aluminates, and the whole field of inorganic chemistry as applied t o the making of inorganic compounds. Class 252 covers “substance preparation” and includes classified patents on refrigerating compounds, flotation agents, and a host of other compositions. Other classes contain patents on liquid coating compositions such as paints, lacquers, and enamels; still others, paten1 s relating to the refining of petroleum, distillation processes, and so on. Generally speaking, patent searches are of four kindsnovelty, validity, infringement, and state-of-the-art-although there is much overlapping. ((
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Novelty Searches
A novelty search is normally concerned only with developing patents and publications which anticipate some specific invention already made. It is not so exhaustive as a validity search and its chief purpose is to determine approximately the patentability of, for instance, a process which has passed I 2
Received M a r c h 2 3 , 1929 P a t e n t lawyer
the experimental stages and is ready t o be embraced in a formal patent application. As a matter of fact, however, it is better t o have a novelty search made just as soon as the laboratory results show something of promise in order to determine as soon as possible whether or not the invention is patentable. If it is not, then it may be advisable t o discontinue the experimental work and, in any event, the patents developed in the novelty search are of material assistance in the further progress of the research. Indeed, instituting a novelty search immediately following the conception of an invention is feasible if there is something more or less definite to look for-that is, if the invention has been conceived in a concrete embodiment. Making a novelty search as soon as possible will often save many dollars otherwise uselessly spent in working out a process thought to be new but which is in fact old. But a novelty search is commonly restricted to some precise invention and is not extended far enough to corer all of a particular field. That is the province of a stateof-the-art search, as will be more fully explained. When making a novelty search, the attorney confines himself to the subclass or classes wherein the invention will most likely be found and to such additional subclasses as would be expected to yield pertinent art. Immediately available foreign patents and literature references, such as Chemical Abstracts, should also be consulted if the nature of the invention indicates that an anticipation is likely to be found therein. Validity Searches
Validity searches, as the name suggests, are for the purpose of developing patents and publications which antedate, and hence invalidate, some existing patent. They are ordinarily made when it appears that a competitor is about to bring suit upon a patent he owns, although validity searches are frequently initiated long before there is any suggestion of a suit in the courts. As an illustration, let us suppose that the XYZ company would like to make and sell a particular type of lacquer, but as a result of an infringement search, wisely made before funds have been expended in a manufacturing and marketing program, it appears that there is an adversely owned patent which will be infringed if the company goes ahead with its plans. Obviously it would not be good business to spend money in developing manufacturing processes and a sales organization to place the lacquer upon the market in the face of a patent that would be infringed if such steps were taken. But if the patent is invalid, then there is no
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legal reason why the company cannot carry out its intention. Accordingly, a validity search is instituted to determine whether or not the adversely owned patent can be sustained in court should an infringement suit be brought. If the search develops art which clearly appears to invalidate the patent, then the company may feel free to make and sell the proposed lacquer without fear of an injunction and an accounting for profits, although they cannot stop the owner of the patent from bringing suit if he so chooses. It is not unusual for the owner of a patent which he thinks is infringed, or which he believes will be infringed, to have a validity search made on his own behalf to determine for himself whether or not his patent is valid, and searches of this character are customarily made prior to the purchase of a patent. T’alidity searches are more exhaustive than novelty searches and extend to all classes and subclasses wherein there is the slightest likelihood of finding anticipating references, and to foreign patents, books, journal literature, etc. The finding of a reference which clearly invalidates an unexpired patent often saves a defendant in an infringement suit thousands of dollars that he would have to pay to a victorious plaintiff if the plaintiff’s patent were not invalidated in the court action. Infringement Searches
Infringement searches are for the purpose of determining whether or not there is an unexpired patent which would be infringed were some process carried out or a certain product made. It is always advisable to have an infringement search made before a process is put into the plant unless it is definitely known that the process is not covered by adversely owned patents still in force. Otherwise large sums of money may be expended only to he thereafter harassed by a suit for infringement. Sometimes infringement searches are made to determine whether one patent infringes another. The issuance of a patent is no guarantee that the patent does not infringe some earlier unexpired patent. Hence in the case of the XYZ company, it may be able to obtain a patent for its particular lacquer yet still infringe an earlier patent which has claims dominating the subject matter of the later patent. Novelty, validity, and infringement searches have their separate functions, but a t the beginning of a research program a “state-of-the-art” search is of greatest value because it reveals patents generally which may be infringed and which may be anticipatory. It is designed to collect all art having to do with the general problem-for instance the utilization of a certain waste material-and can be made reasonably thorough, although it need not and ordinarily cannot take the place of a validity or infringement search. State-of-the-Art Search
A state-of-the-art search has for its object the development of all relevant art prior to embarking upon a program of research and development. To take another hypothetical case for illustrative purposes, let us assume that the XYZ company, in the course of their manufacturing processes, obtain an inert inorganic material as a by-product. The suggestion is made that it might be useful as a filler either as such or after a simple refining process. If uses can be found for the refined material, it is believed that it can be marketed a t a profit. A state-of-the-art search is now desirable, and one should be made before further sums are spent in research and development work. The search, in this instance, would embrace an examination of the patents in numerous classes and subclasses to determine to what extent the material has been used as a filler in cements, plastic compositions, paints, rubber mixes, insulating compounds, etc., together with any processes
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by which it has been refined t o augment its utility. Inspection of patents wherein the material normally results as a by-product would be helpful also because of any incidental statements in the patents as to what the patentee proposed to do with the by-product. A research and development program, with its ultimate objective a marketable commodity and patent protection for what is patentable, can then be planned in the light of what has already been done in the art. From the results of the search, conclusions of great value can be drawn. One of the functions of such a search is to show how the unnecessary expenditure of money appropriated for research may be avoided. Certain lines of research attack may a t once be excluded because they are fully disclosed in the prior patents. This would apply to processes of refining the material as well as to uses thereof, and there have been numerous instances where many dollars have been saved in this manner. I n a search of the character under discussion, a literature investigation may well supplement a patent search, but it can never take the place of the latter. Often unexpired patents are found which would be infringed and it is important a t the outset of an industrial research program to determine how far, and along what lines, research and development can proceed without infringing some unexpired patent. Unless the patent can be purchased, or is known to be invalid, research ought to be directed away from it. It is therefore another function of a state-of-the-art search to point out how the research program may be planned to avoid legal difficulties of this kind. The third function of a state-of-the-art search is to suggest things to be done. With the advantage of knowing everything that has been accomplished in the art, the inventor is in an advantageous position to make patentable improvements on existing processes. A collection of relevant patents is a storehouse of ideas to the inventive mind and the value of such a collection for creative purposes can hardly be overestimated. Most of the chemical inventions of today are improvements on something broadly old, yet control of an improvement rendering an old process commercially practical may mean the establishment of a non-competitive industry. The fourth function of such a search is to indicate with some degree of certainty the scope of patent protection available in view of the existing art. The development of patentable inventions should be one of the major objects of the industrial research program because of the very great economic advantage arising from patent protection. If the art is particularly full, and there appears to he but little room for patent protection, the industry may then be largely competitive and the subsequent investment of money in development can be governed in part by this factor. A state-of-the-art search will also give some indication as to the activities of potential competitors, the lines they are pursuing, and the approximate strength of their patent situation. This information is obviously of p e a t value to an organization about t o embark upon an expensive research and development program as well as to the backers of the project. Finally, a state-of-the-art search, inasmuch as it is broad and comprehensive and pictures the whole art, may develop expired patents, the processes of which are adaptable without patentable modification to the particular problem to be solved. And practicing the process of an expired patent carries with it freedom from harassment. The primary sources in a state-of-the-art search are United States patents. Secondary sources are Chemical Abstracts, examiner’s foreign art, literature references, books, governmental publications, etc. As previously pointed out, secondary sources supplement but cannot take the place of the primary sources, because the latter indicate what has been patented, the trend of industrial development, the scope of
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patent protection available, patents which norm:illy would be infringed and expired patents, the processes of which are feasible in the solution of the particular problem. Thus a search of this kind not only informs the research
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department of what has been done but also indicates what can be done without adverse legal consequences. Thereafter a research program may be planned and executed with a minimum of wasted effort and unnecessary expense.
The Refining of Light Oil with Silica Gel at Rochester, N. Ye1 Rufus E. Fulreader ROCHESTER G A S A Y D ELECTRIC CORPORATION. ROCHESTER. S-. Y
HE recovery of light oil as a by-product from the manufacture of coal gas and water gas was undertaken by the Rochester Gas and Electric Corporation during the war as a source of toluene for the manufacture of T.K.T. After the war the demand for toluene fell rapidly, but an outlet for the product was provided by the motor fuel market, since the merits of light oil as a fuel for internal-combustion engines had already been well established. The method of purification of the crude oil consisted in washing with sulfuric acid and a final distillation, prior to mixing with gasoline, to give a blended motor fuel. A satisfactory product was obtained by this treatment, but it gave a low yield of refined product. The acid used not only removed the undesirable gum-forming constituents from the oil but, in addition, any unsaturated compounds the percentage of which varied with the grade of light oil. Unsaturated compounds of the type occurring in light oil have been shown to have considerable value as a motor fuel, and it was with the idea of retaining these in the oil, resulting in a more desirable product and greater yield, that the silica gel process mas installed a t Rochester. The plant was originally designed for continuous operation with a daily capacity of 4000 gallons. The equipment is housed in a three-story steel-frame building with corrugated-iron siding situated adjacent to the light-oil recorery plant and covers a ground space of 550 square feet. There are two distinct units comprising the plant, the oil-treating unit and the activation unit, the two being separated by an 8inch tile fire wall. It is understood that in future installations the activating unit will not be included as an essential integral part of a silica gel plant. It is planned to have all spent gel returned to the Silica Gel Corporation a t Baltimore, where activation will be centralized, thus reducing initial plant costs and effecting an operating economy. The general layout of the plant is shown in the diagrammatic flow sheet.
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Crude Oil Cycle
The oil to be treated by silica gel is taken from the crude storage tanks of the light-oil recovery plant and pumped through a meter and then to a Venturi mixer where a small quantity of 66" B4. sulfuric acid is intimately mixed with the oil. The amount of acid used is never in excess of 0.05 pound acid per gallon of oil, this quantity being sufficient to.remove all moisture from the crude oil which cannot be completely removed by mechanical separation following the steam distillation of 75ash oil in the recovery plant. This pretreatment with acid is vital, since any moisture in the oil is selectively absorbed by the gel and impairs its refining action on the oil. The oil passes from the Venturi mixer to a settling tank, where any sludge that is formed by Received January 10, 1920.
the acid is allowed to settle out. Two settling tanks are provided so that acid can be mixed with the oil and sludge settled out in one tank n-hile the circulating pump is drawing acidulated clear oil out of the other. The circulating pump is of the piston type and maintains the pressure of the oil throughout the system between 100 and 175 pounds per square inch, this pressure being sufficient t o keep the oil in the liquid phase a t the temperatures required in the process. From the circulating pump the oil passes through a heat interchanger of the shell and tube type, the crude incoming oil passing through the tubes and recovering the heat from the outgoing refined oil. The crude oil then passes through a preheater, where it is heated by live steam to a temperature of 230" F. The crude oil is now properly conditioned for the gel treatment and passes on to the percolator. The percolator is conical in shape, 41/y feet high, and has a capacity of 26 cubic feet. A steam jacket cast as an integral part of the percolator and supplied with live steam allows for temperature control. A centrally guided stirrer for agitation is also provided. Two such percolators are necessary for continuous operation, one being in operation while the other is being charged or discharged. The acidulated oil passes from the preheater upward through the percolator containing a 300-pound charge of silica gel. The temperature of the oil and gel in the percolator is maintained a t 2iO" F. The percolator and circulating pump are of such capacity that the oil is in contact with the gel for one hour, the mixture being stirred constantly during this time. The oil leaves the percolator through two offtake pipes covered with monel metal screens of 350 mesh to prevent the escape of gel with the oil. The gum-forming constituents in the oil have now been removed by the gel and the hot treated oil passes over to the heat interchanger and thence to a cooler, where the temperature is reduced to cooling water temperature. The treated oil is then mashed free from all traces of acid by allowing it t o bubble through a solution of caustic soda and finally runs to the treated light-oil storage tank. The product is now given a final simple batch distillation, which is discontinued a t such a point that the resulting rectified light oil or motor benzene has an end point of 160" F. by the Engler test. Silica Gel Cycle
The chemical composition of silica gel is almost, exactly like that of sand or quartz, though its structure is entirely different. It is made by treating sodium silicate with sulfuric acid. The resultant product is a jelly-like mass which must be dried and crushed t o be used. A grain of 4 i c a gel contains a multitude of infinitesimal capillaries which exhibit a spongy appearance under a microscope. I t is estimated that
