AUGUST, 1936
INDUSTRIAL AND ESGINEERING CHEVfISTRl-
classified. Ander>on and TVilliams (1) report convincing evidence that the animal organism cannot' synthesize either linoleic or linolenic fa.tty acids, both of which are indispen5able. Quoting Burr and Burr (S), they prove that certain fatty acids are indispensable for living animal organisms: "When rats were reared on a fat-free diet, a deficiency disease developed which had not previously been described. This di>ease is rather specific &ice a, scaly condition of the skin develope, while growth continues a t an approximately normal rat'e. Later the tail often becomes necrotic and the kidneys degenerate." Saturated fatt'y acids are ineffective. but eit'lier linoleic or linolenic acid. are t'he outstanding curative or prophylactic agents; so they conclude that warm-blooded animals are unable to Yynthesize linoleic and powihly other of the more highly unsaturated acids. There is much evidence in the literature indicating the advisability of leading the food habits of the general population away from solid fats toward a greater w e of oils, particularly those containing the badly needed linoleic glyceride. It is perhaps significant that those peoples known for the excellence of their cooking instinctively prefer to use liquid oils rather than lard or more modern synthetic vegetable shortenings. It would seem, then, that' a rapid growth in the volume of soybean oil in the national dietary should be distinctly beneficial to the general population. 0
903
Sunimarizing briefly, appareutly a young giant ha* stepped into the picture of agricultural products of our country. Rapid as has been the growth of the newcomer, both the producer on one hand, and the conwmer on the other, have made a sturdy effort to adapt domestic soybean oil to commercial demands. But industry still needs help from research. Where the rewards are so great there can be no question but that help iq on the way.
Bibliography (1) .Inderson, W.E . . and TTillianis. H . H . , Oil aiid S o a p , 12, S o . 12, 282 11935). ( 2 ) Baughman.' K.F.. and Jamieson. G. R.,J . . ~ J J ! . C'heni. Soc., 44, 2947 11922). \-~--, ( 3 ) Burr, G . O., and Burr, SI. SI.,J . B i d . C ' h e m . , 86, 587 (19303. (4) Eisenschiml. 0.. Paint. Oil Cheiii. Rea.. 87, S o . 11, 12-16 (,1929). ~
( 5 ) Jamieson, G. J., and SlacKinney, R. S.,Oil and Soap, 12, No. 4, 70 (1935). (6) Slattill and Craxford, ISD. ESG. C'HEX., 22, 341 (1930). (7) Stewart, C. S., Burlison. TI-. L., Norton, L. J..and Walin, 0. Unir. Ill. .Igr. Espt. .Sta.. Bd1. 385 (Dee.. 19321. (8) U. S. Dept. -Igr., Tearhook of Igriculture for 1931, paragraphs 557-9. (.9) Tushkevich. S . , FettcFie!ii. T - m s c i i n i i . 40, 197-200 (1933).
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SOYBEAN OIL and the Paint Industry E. E. WARE The Sherwin-Williams Company, Cleveland, Ohio
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A l S T interests early realized the necessity for the development of a substitute for linseed oil and the ext'reme desirability of promoting a home-grown product for that purpose. The Paint Manufacturers' Association sponsored experi' mental plantings of soybeans as early as 1910, and the L~ cieiitific Section of the association published a number of circulars dealing with the properties of soybean oil and its utilization in paint products. Comparatively little progress was made from 1910 to 1930 because little domestic oil was available; even after it became available in comrnercial quantities, both it and the foreign oil were handled more or less as an unavoidable by-product whose properties were variable and! in a measure, beyond the control of the producer. The enormous increase in soybean acreage duriiig the past few years brought with it, many problems: some are still unsolved. Since most soybean industrial and food products clemand a relatively oil-free nieal, and animal hushandry experimentation has demonetrated to the farmer thai; he should feed meal rather than the full bean, the utilization of the byproduct soybean oil has become of primary importance. Alt'hough the coiisuinptioii of oils of various'types by paint, varnish, and lacquer iiianufacturers is relat,ively small in comparison with the consumption of fats and oils in other directions (approximately 8 per cent), Burlkoii and other early American iiir-est igators concentrated their efforts on proring
the iuitability of soybean oil for paint purposes rather than parallelirig the research of European and Oriental workers. ~vliofavored food products and ,soap, with the result that the general American public has crmie to consider paint as the natural and economic outlet for the oil froni this important farm crop. The Illiiiois Experiment' Station paintings, d i i c h suppleiiiented the early experiments of Gartliier and Ladd, proved that soybean can be used in high-grde paints, and, to a degree, they have outlined the limitations in the use of the present-day product. Considerable publicity was given to the soyhean oil paints
Soybean oil is not ideal for paint use because of poor drying qualities, but it does possess the excellent characteristics of permanent elasticity and freedom from discoloration. A t present it is seldom used alone; it is either blended with oils of better drying qualities or as a constituent of a synthetic resin vehicle. The utilization of soybean oil in paints and varnishes will progress through pressure of popular opinion and as a result of agricultural and industrial research in the improvement of the product.
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INDUSTRIAL AND ENGrIXEERING CHEMISTRY
used in decorating some of the important structures of the Century of Progress, outstanding among which were the following: American Radiator, Ford, General Motors, Haeger Pottery, Horticulture, Illinois Host House, Irish Village, Swedish, Swift, and Wilson. The excellent performance of the paint on these buildings, from both decorative and protective angles, has helped to make the midwestern paintconsuming public soybean-oil-conscious. These early successes in the use of the new product encouraged the introduction of a soybean program as an important feature in the Farm Chemurgic Council movement. Unfortunately, however, there seemed to have been created the general impression that the introduction of soybean oil in paint is simple and unaccompanied by grief, and also that the demand, if the naturally conservative paint manufacturer could be awakened to his opportunity and obligation, would automatically solve the problem of industrial utilization of this important farm by-product and would relieve the farmer from the necessity of feeding the full bean with the resultant degradation in quality of the fat produced.
Types of Paint The public speaks of paint more or less generically, frequently not realizing that oil paint is only one of the many specialized products used as protective coatings and is by no means the most important one. It is practically impossible to compile accurate figures illustrating the relative importance of items other than oil paint in the protective coating field, but it is reasonable t o assume that oil paints will make up considerably less than half of the total, and a generous share of these are made from oils that, have been specially processed. The type of oil and its proper treatment for paint use varies with the purpose for which the product is designed. For example, a house paint vehicle should be one that will combine ease of brushing, leveling, rapid drying, adhesion, and elasticity with film failure of a type that will give the most satisfactory surface for recoating. An interior wall paint calls for a vehicle whose oil is capable of processing to ensure a final film of absolute uniformity of hiding, smoothness, and sheen, coupled with a maximum resistance to staining and dust collection. It must also have the ability t o withstand chemical cleaners of a more or less destructive nature and must not change color from heat, light, or shadow. A household enamel must possess a fullness of gloss and uniformity of color, to which end the vehicle exerts an important influence, and a hardness to make it resistant t o the abuse of the modern household. A domestic varnish for floors, woodwork, or furniture must be hard, tough, and elastic and must retain its film integrity in the face of the carelessness and mistreatment of the householder who spills everything from whisky t o kitchen grease on its surface and cleans it with anything from sandpaper to the most caustic of washing powders. The vehicles of industrial finishes must meet the most rigid specifications of performance to satisfy the demands of the modern production manager who insists on instantaneous drying, combined with a freedom of flow without sag, curtain, or inequality in film thickness. It must be cRpable of adjustment to meet specific conditions of application (either brush, spray, dip, or roller coat) and must adapt itself to variations in drying conditions from air-drying in zero weather to flash-baking in which the volatile constituent is actually burned out of the film.
Oils Used in Paint Naturally no single formulation will meet all of these conditions, nor have we as yet found a single oil that will adapt itself to such a wide range of demands.
VOL. 28, NO. 8
Practically all paint products carry some oil, but the amount ranges from a negligible quantity in pyroxylin lacquer to approximately 60-65 per cent in outside house paints. The Bureau of Census shows oil consumption to be allocated a s follows (in million pounds), Oil Linseed Tung Perilla Fish Hemp SOY Other
Paint, Linoleum, Ink 1934 1935 350 286 102 111 15 36 25 42 ... 30 13 17 10 10
--Other 1934 S
3 1 100
Uses1935
5 3 5 177
...
...
3605
3962
7
74
Linseed oil is still considered as exclusively a paint and linoleum oil, although small quantities are diverted into other industrial uses such as liquid soap. Its popularity and utility have been assured by years of successful performance, and complete substitution by any other oil is problematical, except as the substitute oil approaches linseed in properties. Tung oil is practically all used in the paint and linoleum industries, the former being by far the more important. Its fast and hard drying, waterproof qualities, and general reactivity will ensure tung oil its place in the varnish and enamel picture. Without radical and probably impossible changes in physical and chemical properties, soybean oil will never replace tung oil. This oil has characteristics of its own and mill be used when available. Any substitution will be compulsory rather than voluntary and will probably be brought about if an insufficient supply forces the price of tung oil to abnormal heights. The same pressure, however, will stimulate the domestic gron-er to supplement his present plantings of tung trees, which now produce less than 1 per cent of our consumption. This movement is already being promoted and will probably result in the production by our own southern states of whatever amount is necessary to supplement importations from the Orient. Even should the shortage of tung oil compel substitution of other oils, it is quite probable that oils more closely comparable to tung, such as the Brazilian oiticica or Oriental perilla, will be used. Such substitutions were made more or less successfully during 1935 and will probably be repeated to a lesser degree during 1936. Perilla oil has in the past never been produced from American-grown seed except in minor quantities from plants grown on experimental plots. During the early months of this year a small tonnage of perilla seed was imported. Part of this is being used for further experimental plantings and part for crushing experiments, but no commercially important quantities of oil will be produced this year and probably not for some years to come. This oil might never have become an important factor in domestic industry had adequate supplies of linseed oil been available. Although perilla dries quickly and hard and its film possesses good weather resistance, its performance is peculiar, especially in air-drying finishes. The paint and linoleum industries will be willing to replace it with linseed or soybean oil of equal drying power. Other industries have never expressed much interest in it. Fish oils have made quite an impression in industrial protective coatings and to some extent may be found in house paint formulas. The oils used are of various origins but the menhaden and sardine, with the possible addition of pilchard, are important in the paint and varnish industry. These oils have excellent drying characteristics under proper conditions, but the difficu!ty experienced and the expense involved in deodorizing the oil have handicapped its sale somewhat. It w& however, continue to make a keen bid for its share of the paint business. Considerable quantities of hempseed (120,000,000 pounds) were imported during 1935. This seed, upon crushing,
AUGUST. 1936
INDUSTRIAL AND ENGINEERING CHEMISTRY
yielded approximately 30,000,000 pounds of oil, most of which found its way into paint and linoleum. Although the drying properties of hempseed oil are somewhat better than those of soybean oil, there is no particular reason, other than price, why it should not be entirely supplanted by domestic-grown soybean oil.
Properties of Soybean Oil
As far as soybean oil is concerned, its freedom from wrinkling and its superior retention of color make it highly desirable for heat-reactive resin formulations, such as baking alkyd resins, and for certain types of interior wall finishes, where linseed oil paints are inclined to afteryellow. The relatively slow drying of soybean oil limits its use as the sole vehicle for strictly air-drying exterior paints where temperature conditions are variable and never ideal. Paints should dry in relatively fast time to simplify the painter's problem and also to minimize dirt collection and danger of washing or spotting from an early rain or excessive dew. The distribution of soybean oil consumption fluctuates with the market demand. Although in 1933 and 1934 a relatively large amount (40 to 60 per cent) was consumed in paint products, during 1935 the percentage was considerably less (approximately 10 per cent). The reasons for this failure of soybean oil consumption to respond to the increase in available supply are twofold: The demand for soybean oil in food products has kept the price a t prohibitive levels, which automatically forces the paint industry to seek substitutes, and soybean oil is handicapped by poor drying and relatively poor film characteristics for general paint purposes unless treated or blended. It would seem that any extensive experimentation directed toward further crowding of soybean oil into the paint industry on a permanent basis will be dependent upon and correlated with experimental work on the bean and the resultant oil to make it dry more like linseed without changing its own desirable characteristics of film elasticity and color retention. Movements are already on foot to promote agrirultural research pointed toward making soybean oil more nearly comparable with linseed. The Farm Chemurgic Council has been instrumental in stirring up interest among agricultural research groups; federal appropriation is now available for a central research laboratory at the University of Illinois, which will undoubtedly work on both agricultural and chemical problems. Judging from past successes of this group of soybean pioneers, we may expect that the agricultural program will result in a bean whose oil will show decidedly improved characteristics. Soybean processing interests have awakened to the necessity for broadening and stabilizing their markets in anticipation of the return of cottonseed oil and animal fats to practical domination of the food industrial consumption. The S o v b e a n Crushers Association i s c o m 12 3 mitted to a program I1 which should make the most of its opport u n i t ies , both from 9 the angle of control of I initial processing and also a l o n g lines of +I 5 subsequent r e f i n i n g "6 operations. Crushers have noted radical differences in the quality of oil f r o m b e a n s grown in d i f f e r e n t localities and under 1996 e29 1950 1931 n
903
different climatic conditions. They are also satisfied that variations in crushing procedure will influence quality a t least to the extent that separations may be made during the pressure build-up in the expeller. The oil from the early stages has somewhat improved properties over the oil of the highpressure stages. Refiners of soybean oil are studying bhe possibilities of their processes and have shown ability in standardizing the quality of their output. They have been able to improve drying somewhat by removal of antioxidant bodies but as yet have not produced an oil that hardens equivalent to linseed oil when used by itself in air-drying paint products. Independent researches are keenly interested and will be bringing forth worthwhile findings. Kraybill's experiments on soybean phosphatides and Working's research are certain to add much to our knowledge of the performance of soybean oil and the possibilities of modifying it for specific operations. I n the past there has been a tendency toward the drawing of false conclusions from experimental work covering the success of refining processes on the drying qualities of soybean oil. It may be true that acid and mild preoxidation treatments will remove the antioxidants to such a degree that drying comparisons between the treated and untreated oils without drier additions show much in favor of the former; on the other hand, when normal drier additions are made to bring the drying time within limits set for paint products, no outstanding advantage other than uniformity may be claimed for the treated oils. I n the early experiments on soybean oil it was customary to recommend extra drier addition as a means of overcoming the slow-drying and aftertack of the oil, but the results obtained did not justify the continuation of such a recommendation. Practically all soybean oil in today's paint products is accompanied by large additions of fast-drying oils such as tung or perilla. In many cases this addition is gallon for gallon.
Future of Soybean Oil If an apparently misinformed Congress carries out the proposed plan of placing a sufficiently heavy tax on imported oil, such as perilla, to limit its use as a reinforcing agent for soy, we may expect this tax to react as a serious handicap to our efforts in the direction of greater soybean oil consumption in paint products. The total U. S. consumption of linseed oil in paint, linoleum, and ink is, according to Bureau of Census figures, between 250,000,000 and 350,000,000 pounds. Of this quantity, a t least half is crushed from imported seed. The 1935-36 soybean crush will be between 25,000,000 and 30,000,000bushels of the 39,000,000 crop of 1935. If we max assume a conservative figure of 8 pounds of oil per bushel of beans, we have a t least 200,000,000 pounds of soybean oil from the 1935-36 crush of beans. This almost quadruples the crush from the 1934 crop. Of this quantity, p r o b a b l y not more than 5,000,000 pounds a d d i t i o n a l will go i n t o p a i n t products, making a total consumption of approximately 20,000,000 pounds. This will be due to the fact that the food product demand on soybean oil keeps the market p r i c e a t an a b n o r I J mally high level as 1932 1933 1934 1935 1936 compared with the
INDUSTRI4L kND ENGINEEKIVG CHE\IISTKY
906
price of the better tlryiiig linseed and perilla oils, which demand, the oil crusliers belieTe, will continue throughout the 1936 consuming season. This contention is supported by a Washington Sews Letter' Tvhich makes the rather startling, though from the soybean oil producer's standpoint, encouraging statement: "The major new domestic source of vegetable oils has been the soybean. But increases in that crop, a t an amazing rate in the last few years, have made available new oil supplies barely sufficient to t'ake care of 5 or 10 per cent of the deficiencies. Further large increases in soybenn supply cannot be expected t o meet the oil situation until simultaneously we find new outlets or iiev uses for bean meal necessarily produced." If we assume that tlie removal of restriction on oil seed crops and on the raising of hogs and cat'tle will bring the normal quantities of cottonseed oil and animal fats into the food products market, it seems certain that part of the soybean oil now used in food products will seek other channels of consumption, probably soap and paint. Unless agricultural and chemical researches result in soybean oil improvement beyond most optimistic expectation, we cannot legitimately expect' it to replace linseed oil from doniest'ic-grown seed. In the light of our present knowledge of soybean oil processing, the most opt,iniistic paint technologist ~vouldprobably not predict t,he replacement of any of the domestic and not more than half of the oil from imported flax. If these predictions are reasonable, n e may not hope to absorb into paint products more than 25 to 50 per cent of the soybean oil that will be diverted from the food industries if cottonseed and animal fat production return to normal, and little, if any, of the oil resulting from an increased planting program.
Difficulties i n Marketing The Paint Manufacturers' Association as a group and its members as individuals are vitally interested in doing their utmost to further the interests of the domestic producer and processor of paint oils. It must be acknowledged, hon-erer, that' we are handicapped by conditions seemingly beyond our control. While n-e have, by processing and blending, been able to produce soybean oil paints of outstanding characteristics, there seem to be almost unsurniountable obstacles in the way of their universal marketing, except in special industrial finishes. Here soybean oil products hare been able to prove their worth, and it' is evident that such increases in aoybean oil consumption as have been shown for the last twoyear period have gone into products in which t'he price differential over other drying oils has been offset by superior performance. The railroads, particularly those of the West and Sorthwest, have recognized the gravity of the situation and have inserted ti soybean oil clause in their paint specifications demanding that a considerable percentage of the oil cont'ent. 1
Chem. R. M e t . Eng., 43, 15i (1936)
VOL. 28, 50.8
shall be soybean oil. The Sorthern Pacific, Missouri Pacific, and Burlington Railroads are particularly insistent that soybean oil constitute a t least part of the oil content. The Sorthwestern and other railroads are vitally interested and will undoubtedly change their specifications shortly. Analysis label legislation in a number of the states, originally proposed t'o protect the retail consumer from the unscrupulous manufacturer, quite properly required the use of any oil other than linseed to show on the label. -1s a result the paint-consuming public has become so thoroughly sold on the merits of linseed oil that a paint label showing soybean oil immediately sets up a prejudice in the mind of the prospectire buyer. with the result that the retail sale of soybean oil paint in districts other than those whose personal interest lies in promoting the grom-ing of soybeans is extremely difficult. The education of the indii-idual consumer to a n appreciation of the value of the new paint' is a task seemingly beyond the power of printer's ink. This education must come through channels other t.han that of paint manufacturers' ad\-ertising literature. The Federal Specifications Board was instrmnental in relieving the linseed oil situation during the World War. Thousands of gallons of fish oil paint were used during that period. I t would seem that thew might be some such agency through which government interests other than legislative might be inspired to a n int'ensive educational program on soybean oil. It is unnecessary and practically pointless that legislation should be promulgated to force the use of domestic products such as soybean oil by restricting, through tariff regulation, the use of imported oils for which soybean oil may substitute, while a t the same time federal, state, and municipal specification writers are setting up paint specifications that practically demand the imported oils. We cannot hope to interest the average coiisiuner in the use of a new product of somewhat changed characteristics, when the technical agencies to whom he looks for advice and guidance tell him through the medium of such specifications that the product we are introducing is of inferior quality. It is true t,hat a certain number of consumers may be reached through tlie farm bureaus, but such agencies can hope to be effective only in agricultural districts growing soybeans and will be totally ineffecbii-e in urban or nonsoy-grom-ing farm districts. The paint industry should be using more soybean oil, is anxious to do so, and is able to formulate excellent paints from t'he domestic product. The situation calls for a program of research and education rather than one of legislation, agricultural research to improve strain, processing research to make the most of what n-e may be able to induce nature to give us, and consumer education to cultivate demand for the type of paint that soybean oil will give us rather than the type that is a t present prescribed by legislation and prejudice. RECEIVED .\pril 29, 1936.
