-Synthetic
Detergents-
Household and Industrial Use LAWRENCE FLETT,
National Aniline Division,
Allied Chemical & Dye Corp., 40 Rector S t . , New York, N. Y.
In industry synthetic detergents are used when it is desirable to bring any water-insoluble liquid, solid, or gas into contact with any aqueous treating solution. Detergents are used to speed up the treatment, to make i t more complete, or to make it possible; in general better quality is expected. Practically all industrial markets, outside the textile industry, depend on new uses made possible by the unusual properties of synthetic detergents. Household detergents, however, entered a market that was well established by substantial sales of soap. Soap washes slowly but very well; the synthetics wash with great speed but require special formulation to match the washing of soap. Special properties of the synthetics are leading to new cleanliness practices that, in the future, should create a broad expansion of their markets.
A
COSSIDERATIOS of the household and industrial use of detergents is inteiesting because while there is a great deal of similarity, there is also a great deal of contrast in the two uaes. The word “detergent” means many things t o many people. I n this discuesion, it means products that really wash-products that take the dirt out of textiles such as cotton and wool. As the term is now commonly used, i t excludes soap, even though soap is, strictly speaking, a detergent. Detergents are surface active agents, so in addition to dispersing action that makes washing possible, they show the other tension common properties of surface active agents-surface lowering, wetting, emulsification, penetration, and sudsing or foaming. When detergents are used in the home, the housewife expects each and every one of these properties t o manifest itself. I n contrast t o this, in industry, the utility of the detergent is generally limited to one or two specific properties. The other properties may be without effect or may even be harmful. I n discussing industrial uses, it is helpful to remember that detergents were developed by the textile industry. It is easy t o understand the necessity of cleanliness in processing textiles like cotton and woo1 cloth. Consider, for example, the dyeing process. If goods were not cleaned before they were dyed, the dyeing would be uneven and unsightly. Soap was the only material that would do this cleaning until 1930. The use of soap is very old. It does a good job of washing, but there are many limitations to its use. It must be used in alkaline solution, whereas textile operations are often carried out in neutral or acid solution. It is difficult to rinse away. And most troublesome of all, soap is precipitated by both lime and metal salts. To make matters worse, these precipitated soaps gather into gummy masses which stick t o the goods. They make waterproof spots that repel dyestuff solutions and so leave white spots on the goods. The correction of these white spots is very expensive; so ever since people have been using soaps and dyes, they have been seeking wetting, dispersing, and washing agents that would be unaffected by lime salts, acid, or heavy metal salts. The dyer was willing to pay a high price for a detergent that would solve the problems brought about by soap. Shortly after the middle of the last century, the sulfonated oils were developed, and those were followed by a long list of so-called wetting agents. All these surface active agents did most of the things the dyer needed done without the serious defects of soap, but they did not have the most important property of soap-the good washing action. Then, finally in the late
September 1954
’ZO’s, the impossible was accomplished. The goal of decades of research was achieved. Detergents, products that could really wash and products that were free from the defects of soap, became an accomplished fact. The new detergents were introduced into industry in this country in 1932, so their industrial history is just over 20 years old. Contrast this with soap which has a history of more centuries than the new detergents could count years. Such a development was certain to have a profound effect on the whole field of wet processing and on the field of soaps and wetting agents. Here was something new that mill people and chemical processors had been looking for. The demand for such detergrnts already existed. Here was something the long-suffering housewife in hard water areas had always wanted. There was no ready-made market for the detergents outside of certain uses in the textile industry. There was a large latent demand for surface active agents with such unusual properties, but few uses outside the textile industry could justify the high cost of the early production. Nevertheless, new industrial uses were quick to develop. New uses meant more production and made i t possible for industry t o lower costs. It would not be possible to enumerate all the uses of detergents; most oi them are well known by now. It may be interesting t o cite examples of the industrial uses that depend on one specific surface property and where there is little interest in the other properties. The sudsing property of detergents has made possible stronger lighter plaster by the introduction of very fine bubbles. These same bubbles make possible portland cement roads that do not disintegrate under alternate freeeing and thawing. Good suds make possible foam rubber and foamplastics. The wetting property is made use of in the application of insecticides or fungicides so that they may be distributed uniformly over waxlike surfaces of leaves and fruit. The property of emulsification is useful in the manufacture of cutting oils, in wool scouring, and in cosmetic preparations. The lowering of surface tension, which speeds the drainage of water from the dinner dishes, is also used to promote the drainage of water from coal so t h a t it will not freeze into a solid mass in cold weather. Many of the new industrial uses were phenomenal, because they depended on diametrically opposite properties. The importance of detergents in washing-that is, forcing the dirt away from things-is obvious; nevertheless, they are used to penetrate finely divided solids or latex emulsions into textiles. They are used a s emulsifying agents as, for example, in the scouring of wool or in the application of oily insecticides; they are also
INDUSTRIAL AND ENGINEERING CHEMISTRY
1915
usrd for breaking petrolrum emulsions. They are used for \vetting a i d for waterproofing, for sudsiiig and for defoaming. These anomalies depend on the x a y the detergent is used and to some extcnt on the purpose for which it is used. Primarily, detergents are used for the dispersing action that makes t'hem n-ash. They speed up dispersion. Certain det,ergcnts are effective under almost, any conditionf. This property leads to the most important indiist'rial use--the acceleration of wet processing. IVherever any iwter-insoluble material-regardless of whether it is a solid, liquid, or gas-is t o be treated with water or an aqueous solution, it is almost a certaintl- that the operation rvill iie speeded up by use of a synthetic detergent. Froni such processes, i t is reasonable t,o expect a purer improved product. Detergents can clean crystals in the chemical processes as effectively as they can clean drinking glassrs. Some dpiergents stand up under the most rigorous condition?; they may be used even in st'rong hot, acids or alkalies of t'ke cliemical reaction liettlr. In industry, it is common t o take advantage of the improved processing rate to increase production. Sometimes advmtage is taken of the more rapid action to achieve a better result-for example, a cleaner more sterile bott'le from the bottle \vaFher or a better enamel job on a new automobile. The ability of detergents t o speed up operations has led to their almost universal use in the textile industry, of which they are an indispensable part'. INDUSTRIAL MARKETS
The industrial market for soap was small in 1030, Ivlien the detergents were introduced. There was a fair amount used in the text'ilc industry and later some 135,000,000 pounds for processing synthetic rubher. Those marketing synthetic detergents to industry found little made-to-order busines,! out,side thr textile field. Severtheless, industrial uses have expanded rapidly, far beyond the limits indicated by the restricted soap market. *kt t h e present time, the industrial market for detergents is cstimated to be about 300~000,000pounds per year. The importance of the detergent industry t o the nation is far greater t'han the amount used would indicate, because the detergents are used in remarkably small amourits to achieve remarkably Iargr effects on production and product quality. From the longrange standpoint, she industrial market i8 still regarded as new and certain t o develop. It is estimated that another 5 years n-ill see the industrial use mount, to 500,000,000 pounds per j m r , but this is still small compared to household uses. HOUSEHOLD USE
In contrast to the industrial market, the household use of v,-ashing agent's was well established when the synthetic detergent first arrived. The householder had found out how to use soap and holy to live with its faults, even in parts of the country where mater was w r y unfriendly to soap. Although soap bothered the housewife: she definitely was not going to pay t'he high price the dyer paid for detergents when t'hey were first produced. Vhen detergents were first introduced, they were so new and interesting that they fascinated all workers in the field. Although the price was high, it was not long before American chemists visualized the possibility of low- cost materials, and lory cost materials were soon made available for household use. The detergents, as first inwoduced into the home, had limited use. The common neutral mixture of active organic detergent and sodium sulfate was remarkably effective for washing woolens; just a few squeezes in almost cold water, and dirty socks w r e clean. There is very little shrinkage xhen woolens are washed this way. Detergents also gave sparkling dishes without drying. It has been showi since that cert'ain detergents, by a combina-
tion of washing and antiseptic action, give a cleanliness to t1w dinner dishes that approaches sterility. The really great advances in the production of household detergents came viith the development of the so-called heavy-duty detergent-that is, the allialine drtergent built iyith tripolyphosphat,e. These products found immediate accept,ance for the home laundry because they could wash cotton, whereas the original neutral mixture was a very poor cot,tou washer. Recauso of their slippery, soaplike chaiact ics, many people preferred the huilt detergent. They filled the household needs. SOIT, finally, the housen-ife in hard water areas had a washing material that would do all her houschold washing with amazing speed and without the scum from hard water soap. The established packaged soap market \vas a ready-made market for detergents, particularly in those areas where the houseir-ife had been bedeviled bj- hard water soaps. Hrre wits the opport,unit,yfor the tylw of broad promot'ion at xhich the soap companies are masters. MARKETS FOR HOUSEHOLD DETERGESTS
The consumption of solid soap in the household amouiited to 2.8 billion pounds the year before detergents were introduced. In 1953, it amounted to 1.95 billion pounds. The figure is somewhat deceiving. Soap is reported in terms of pounds sold, but the fatty content of soap, varies. I n the past, it was common prnct,ice t o build soaps with large amounrs of cheaper slkalirie salts. For t'his reason, a better comparison can be niadc bctxecn the amounts of fats used for soap. The actual consumption of fats in soap Tr-as about 1.6 billion pounds when the detergcnts were introduced in the '30!s, ana was about 1.4 billion pounds in 1953. I n cont'rast t o the declining soap market, the householtl detergent market, which started from zrro in 1931, is cstiniatetl a t over 2 billion pounds for 1953. I t haa obviously yrorvn at some expense t'o tho existing soap market: ne\-crthelesa, the per capita household consumption o i soaps and detergents is Iiigher than the per capita use of soaps xvhen detergc-nts w r e int~roduced. FUTURE m m E r S
S e w uses for detergents i n the home and in industry hiive 1.csulted in a continual niid consant expansion of detergent production. The synthetic detergent marlict, not\- less than 25 >-piLrs' old, has developed faster than any other synt,hetic market has ever developed. It stands tad thetic plastic market and the which is the greater part of 100 \That has happened t o soap'? Soap has not heen cromled off the market. mhile the detergiants can he made into cake form, of thr cake of soap. The soap people st,ill like t'he charactcri~tic~s cake ivill not disappear in our lifetime. So:~p still docs a fine laundry job where plenty of soft witcxr ie available. Mixturce of synthrtic and soap have useful properties and will be marketed. It is snt,icipat,edthat consuniption of soap is close t o its l o ~ v r s t ~ level and that it will expand ~~~~~ly in the future. The synthetic detergent' market, on the other hand, n-ill coritinur to expand rapidly as new uses are developed in industry arid as its utility increases in the home. I tlet,ergcnt production of 3 kiillion pounds within 5 years should be a rrasonable forecast. It ie obvious that the expanding mri~~ltrt~ for the detergents rneaiis laxer cost. It means greater cleanliness in the home and rlea,ner people. It means more chemists and more research. N o r e research means better detergents to make norlr easier for the overburdened houseivife. -ill of us will lire under more pleasant coiiciitions. Above all, it mcnns a healthier nation. Here in this country, we hare cnjoJwl a health f a r above that oi the rest of the worid. Cleanliness has been a mainsta:: of that rccord. KECIXITED for review hlarch 2 3 , 1934
ACCEPTEDJuly 6 , 1% L.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 46, No. 9
.-.-i
1916
