US2243054A - Detergent composition and manufacture thereof - Google Patents

Description

Patented May 20, 1941 UNITED sraras PATENT {O ICE DETERGENT CM1POSITION AND MANUFACTURE THEREOF James G. Vail, Media, Pa", assignor to l hiladelphia Quartz Gompany, Philadelphia, Pin, a corporation oi Pennsylvania No Drawing. Application November 27, 1937,

Serial No. 178,931

acid being such that the final product contains.

at least about'5 per cent of soap and a substantial proportion of alkali metal silicate, advantageously having a molecular ratio of alkali metal oxide to $102 ranging from about 1:1.5 to 1:3.3. My invention also includes the detergent composition formed as a result of the de-- scribed process, this detergent comprising particles of an alkali metal silicate substantially may be avoided by cooling the frames as quickly as may be convenient, thus increasing the viscosity and in efiect producing a frozen heterogeneous mixture. This process is time consuming and has rather severe limitations since the soap and silicate are not miscible in all proportions and the more siliceous silicates are likely to take up alkali from the soap, resulting in a grainy condition. If the product is made in the form of bars, the amount of silicate which can be added is limited by the shrinkage of the bar soap upon drying and also due to the fact that a highly silicated soap hardens and becomes difiicultly soluble upon ageing.

Spray dried mixtures of silicates and soap are manufactured by spraying a fluid mixture into a current of hot air, this operation causing the evaporation of much ofthe water present and producing a product inthe form'of small bubuniformly combined with at least about 5 per cent of an alkali metal soap formed in'situ by reaction of said particles of alkali metal silicate with a fatty acid, said particles containing alkali metal silicate, advantageously having a molecular ratio of alkali metal oxide to SiOz-ranging from about 1:15 to 1:3.3; all as more fully-hereinafter set forth and as claimed.

The field of detergents is one of the most ancient of the chemical arts. Fats and fatty oils have been saponifled with alkalis of all types and it has long been known, for example, that soaps can be made by the use of alkali metal silicates as saponifying agents. It has also long been known that fatty acids can be substituted for the fats and fatty oils in the manufacture of soaps. Alkali metal silicates have been used not only as saponifying agents but also as builders for soaps and it has been definitely established bles, having a high specific volume and ready solubility. A substantial amount of water is evaporated during the spray drying process. Spray cooling processes are also known for making mixtures of silicates and soap. In these processes it is necessary to add roughly 20 per cent of sodium carbonate which eliminates the necessity for evaporating the Water present. But

that the presence of alkali metal silicates substantially increases the detergency of soaps with which they are mixed. But no entirely satisfactory commercial process has as yet been'proposed for incorporating alkali metal silicates in soaps in the desired proportions. a

The usual process of making silicated soaps is to crutch, that is, to mix a hot kettle soap with a silicate solution at a temperature in the neighborhood of 140 F. until an apparently homogenous mass is produced. The resulting mixture, which is poured into frames to cool at this stage, is not at equilibrium, however, and-always exhibits more or less tendency for the silicate solution to separate in the frames. Separation the product thus formed is not as desirable from a detergent viewpoint. Both of these processes are diflicult to control and are costly. In the present process evaporation of the water is entirely avoided and it is not necessary to add extraneous salts.

I have found that solid alkali metal silicates "will react readily and to substantial completion with fatty acids of high molecular weight in the substantial absence of water to form a homogeneous product, provided that the physical state of the alkali silicate is such as to expose a large surface area per unit of volume, that is provided that its specificsurface (surface divided by volume) is sufliciently large ,or that its apparent specific gravity is sulficiently low, 1. e. provided that expanded silicates are employed.

This process is characterized by the fact that,

unless the particles of alkali metal silicate are disrupted during the reaction, by grindingfor example, the particles of the resultant product are substantially determined by the physical characteristics of. the particles of the silicate used in the process. If a so-called intumescent silicats is employed, having an "apparent specific gravity of the order of 0.1, for example, the speci fic gravity or the resulting product may be in creased to-about 0.3, but this product otherwise in my process.

possesses most of the physical characteristics of the silicate from which it was made. Even the shapes of the silicate particles are retained. The mechanism of my reaction thus appears to be a saponification which proceeds from the interface between 'the silicate and the fatty acid,

resulting in the formation of a solid soap in apparently homogeneous'relation to the silicate which may be present in large amounts, the soap being formed on the alkali nuclei by accretion but penetrating to the cores of the particles, that is, completely through the silicate. This enables my product to be identified and distinguished from products. of similar composition produced by other methods.

The reaction between the alkali silicate and the fatty acid in my process can be conducted at temperatures ranging from room temperatures to temperatures approaching those at which the fatty acid is decomposed or volatilized. Temperatures above the melting points of the fatty acids are advantageous. One important advantage of my process is that temperatures substantially below those causing damage to the fatty acid can be employed. At the lower temperatures, if an anhydrous silicate is used, it is desirable to add a small amount of water to the process since otherwise the reaction is time consuming. The amount of water required, however, amounts to only about 1 to per centby weight, based on the weight of the mixture. When a hydrated silicate is employed the addition of water is not required. It will-be noted that one molecule of which is heated. When a liquid 'fatty acid is employed, mixing may be accomplished by the use of an ordinary rotary drum. If desired the solid silicate can be added gradually to the liquid fatty acid and this mixture agitated until the desired granular product is obtained. When a flaked silicate is employed the process of flaking and mixing can be combined by spraying the fatty acid over the film of silicate formed on the rotating drum prior to the scrapers. The silicate and fatty acidcan be ground together during the reaction if desired. A considerable amount of heat is given off during the reaction.

If the product is to bC-StOICd prior to use, the silicate particles can be coated with fatty acid in the cold and the reaction allowed to proceed to It is seen from the above that my process produces a product which is stable and homogeneous water is formed during the chemical reaction inthat the amount of water desired in the flnal product can be accurately predetermined by the addition of the required amount during the process. A certain amount of water is usually desired in my detergents since this makes the products more readily soluble.

I have found that the use of the so-called intumescent silicates is particularly advantageous These silicates are formed by rapidly heating hydrated silicates to expel part of the water in the form of bubbles which expand as they are released from the surface of the more-or-less plastic silicate, resulting in a highly porous product of very low apparent specific and which possesses the greatly desired characteristics. of rapid solubility, and lightness in Y weight. 'This'process is capable of producing compositions containing widely varying ratios of soap to silicate and also widely different ratios of alkali metal oxide to silica in the silicate component of the product. It should also be mentioned that my reaction" goes to substantial completion which is in contrast to the process in which fatty. acids are reacted with sodium carbonate, for example, which process is incomplete and requires the addition of caustic soda in order that the fatty acid should be completely saponifled.

It is possible, of course, to add other detergent salts during my process. Examples of suitable salts are sodium carbonate and phosphates, which may be added in the form of their solutions, if desired. These salts appear in the final product in more-'or-less unchanged form. They are not required in th Product, however, and in some gravity. Advantageous results have also been obtained by using flaked silicates produced. by the rotation of cooled drums in heated, concentrated silicate solutions, followed by scraping the resulting films of silicate from the drums. These flaked silicates also have very low apparent ape-- ciflc gravities and large specific surfaces. Spray dried silicates of low apparent specific gravity are cases are not desired. a

The following specific examples illustrate certain processes which are wlthinthe scope of the present invention and which represent practical methods of making my novel products.

Example 1 56.! parts stearic acid were melted in a mixer and agitated at about 70 C. 33.3 parts of anhydrous crystalline metasilicate (Na:SiOa)-65 mesh-were added, this product having an appar- -The product had an apparent density of about 0.7.

Example 2 parts of expanded NazO.2SiOa containing 14 per cent water and an apparent density of are usually more advantageous.

about .04 were agitated by rolling in a drum at about 25 C. Oleic acid, 100 parts were distributed over the moving mass which remained solid throughout the process, but lost its apparent oiliness as the reaction proceeded. The temperature rose to about 45 C. and the final product had an apparent density of .18. A similar product was made with melted stearic acid at about 70 C. This had an apparent density of 0.2.

Such products made with redoil are soluble in cold water, while hot water is necessary to dissolve the products made from stearic acid.

While I have described what I consider to be the more advantageous embodiments of my process, it is evident that many modifications can be made in the specific procedures which havebeen described, without departing from the purview of this invention. As mentioned previously, it is merely necessary to thoroughly mix a soap-forming fatty acid with a solid expanded silicate in suitable proportions'to produce the desired reaction, this reaction usually taking place even in the absence of added water. When water is added, this may be accomplished by the addition of. a suitable solution of an alkali metal silicate or of another salt, the water thus added appearing in the final product and tending to make the latter more readily soluble. The addition of silicate solutions as sources of water for the reaction-is a useful means of regulating the ratio of alkali to silica in the finished product. Any soap-forming fatty acid can be used in my process, oleic and steanic acids being chosen to illustrate high and low melting points. The fatty acids used in the process may be dissolved in a suitable solvent, such as petroleum ether, prior to or during their admixture with the silicate, if desired. The silicates of various alkali metals can be employed. For example, expanded potassium silicates can be used in place of sodium silicates and are capable of producing very similar products. While I prefer to employ solid silicates having apparent specific gravxities ranging up to about 0.7, somewhat more dense products can be employed provided that a longer time is allowed for the reaction to take place. The lighter weight silicates produce lighter weight products if the same amounts of fatty acid are added, and the lighter weight products It is possible to produce products having apparent specific gravities as low as about 0.1, for example, this value rising to about 0.9 when the heavier silicates are employed. Intumescent silicates having apparent specific gravities as low as about 0.01 can be produced and are useful in my process. The resulting products have little tendency to produce dust. I have also subjected spray dried silicates to a rapid heating to produce intumescence, thus obtaining an extremely light-weight silicate for use in my process. While my process can be varied in such manner that the residual alkali metal-silicate in the product has a rather wide range of molecular ratios of NazOto $102, the more advantageous detergents within this invention contain silicates wherein this ratio lies between about 1:15 and 1:33. It has been found that the particles of my detergents usually contain somewhat higher proportions of soap on the surface than in the interior which serves to distinguish my products from the usual silicatedsoap products. This difference is so slight, however, that the products can be called substantially homogeneous. Other modifications of my process which fall within the scope of the following' claims will be immediately evident to those skilled in the art. What I claim is:

1. As a new detergent, particles of an expanded alkali metal silicate substantially uniformly combined with at least about 5 per cent-of an alkali metal soap formed in situ by reaction of said particles of alkali metal silicate with a high molecular fatty acid, said particles containing slightly larger proportions of soap on. their surfaces than in their interiors, said detergent having an apparent specific gravity between about Y 0.1 and. 0.9. v

2. The product of claim 1 wherein the alkali metal silicate component contains alkali metal oxide and SiOz in a molecular ratio ranging from about 1:15 to'1:3.3.

3. The product of claim 1 wherein the alkali metal silicate component is sodium silicate containing NazO and SiOz in a molecular ratio varying from about 1:15 to 1:3.3.

4. As a new detergent, intumescent particles of a sodium silicate substantially uniformly combined with at least about 5 per cent of a sodium soap but containing on their surfaces slightly larger proportions of soap than in their interiors, said particles having an apparent specific gravity ranging fromabout 0.1 to 0.9, said sodium soap resulting from the reaction of a highmolecular fatty acid with said intumescent particles of sodium silicate.

5. The product of claim 4 containing sufficient water to make it readily soluble.

6. As a new detergent, expanded particles of a sodium silicate substantially uniformly combined with at least about 5 per cent of a sodium soap formed in situ by reaction of said particles with a high-molecular fatty acid, the sodium silicate in said product containing NazO and SiOz in a ratio varying from about 1:15 to 123.3 and the apparent specific gravity of said product varying from about 0.1 to 0.9.

7. In the manufacture of detergents, the process which comprises slowly agitating granular particles of an expanded sodium silicate, having an apparent specific gravity not substantially exceeding 0.7 and having a molecular ratio of NazO to S102 within the range of about 1:15 to 1:3.3, in the presence of liquid, soap-forming fatty acid in amount suflicient to form at least