US1831610A - Manufacture of soap - Google Patents

Description

Patented Nov, 10, 1931 UNITED STATES PATENT OFFICE EUGENE SCHUCK, OF LOS ANGELES, CALIFORNIA, ASSIGNOIR. OF ONE-FOURTH TO GEORGE E. MCCREERY, DE LOS ANGELES, CALIFORNIA MANUFACTURE or-s'onr No Drawing.

This invention relates to an improved method for the manufacture of .soaps of high soap content and low water content and which are moreover stable and durable.

The ordinary methods of soap manufacture result in the production of soap of high water content. In order to produce soap of high soap and low water content, the soap of high water content has been subjected to a drying operation. In general, two methods of procedure have been followed in making soap of high soap content and low water content. According to 'one method, the fatty material is saponified in large kettles, with boiling and final settling .of the soap, which is then run over cooling rolls, shredded and dried in a suitable dryer. Ac cording to the other and older method, the hot soap from the soap kettle is cooled in frames, cut into slabs and bars, shredded with the socalled chipper, and placed on drying screens to be dried, either byletting it stay on these screens long enough or by putting the screens into a drying chamber. Soap can be produced according to these and other methods qtt manufacture which contains a high percentage of soap and a low water content, but they involve expensive drying and other operations, as well as costly machinery, and they consume a great deal of time.

The present invention provides an improved method in which such objectionable drying and other operations are eliminated or greatly simplified, and in whicha soap of high soap content is directly produced in a simple and advantageous manner.'

I have found that if glycerides of animal or vegetable origin and containing a varying percentage of free fatty acids are intimately mixed with alimited amount of water, sufficient to dissolve the caustic alkali employed, and finely pulverized caustic soda or potash then admixed under conditions described bewith a hot freshly formed solution of caustic v alkali dissolved in a minimumamount of wa- Application filed March 19, 1930. Serial in. 437,273.

soaps can be thus produced which are perfectly saponified and do not contain more than 0.025% free caustic alkali, the saponification being more complete than that obtained with cither'the boiled or the so-called cold and semi-boiled processes of soap manufacture. The soap is moreover, directly produced with a low water content and high soap content so that further drying is unnecessary.

The following more detailed description will further illustrate the process of the invention:

A suitable quantity of animal fat or vegetable oil is placed in a mixer with revolving screw or paddle arrangement for bringing about intimate mixture of the fatty material and added ingredients. The temperature of the fatty material may range between about 100 and 150 F. According to the saponification number of the fatty material, powdered caustic soda of 76% sodium oxide (Na O) is carefully weighed and prepared for adding to the mixer. One part of such caustic soda can be dissolved in about 0.4 to 0.7 parts of Water, thereby forming solutions of caustic alkali having concentrations of about per cent and 58 per cent respectively. A I

suflicient quantity of water for dissolving the weighed amount of caustic soda is added to and intimately mixed with the fatty material in the mixer. Then the powdered caustic soda is slowly added under constant agitation or admixture until the mass presents a uniform emulsified appearance. Caustic alkali and water may 'be used in any ratio not less than one. An aqueous caustic alkali solution is saturated at ordinary room temperatures when equal parts of water and alkali are employed. The use of alkali solutions having concentrations lower than 50 per cent involves the introduction of excess water which of course is one factor found.

in ordinary soap manufacture which is avoided in my novel process.

This emulsified mass is withdrawn from the mixer as soon as it begins to thicken and is collected in a suitable receiving tank. In a few minutes, a self-heating process takes place. The mass develops such an intense r saponification is about 40.7 parts.

heat that its temperature rises, e. g. to around 300 to 320 F, with formation of steam and raising of the mass in the container. This generation of heat and accompanying saponi- 5 tication process continues, according to the size of the batch, for a period of several minutes, e. g. around 8 to 10 minutes, more or less, ai'ter which the newly formed soap settles back in the container. After standing or a further period of time, for example. around 25 to 30 minutes, the saponification reaction is substantially completed, and the hot liquid soap can then be removed from the container and cooled, for example, by passing it between revolving water cooled iron rolls, revolving against each other. on which it is cooled and solidified, and from which it can be scraped off or peeled off by knives closely set against the rolls. The soap 0 is thus directly produced in a flaked or shredded form and may be either packed immediately as soap chips, or it may be pulverized and formed into powdered or granulated soap. or it may be further treated, for example. by passing it through a plodding ma-- chine to form milled toilet soap.

,By using a limited amount of water, sufficient to dissolve the powdered caustic soda, and mixing it with the fat before the caustic soda is added, the caustic soda, when added, dissolves in water which is distributed through the fat, forming a saturated or nearly saturated solution of caustic soda in the water which solution then acts upon the fat to bring about rapid and complete saponification. Owing to the limited amount of water employed, there is no large amount of Water to be removed. Some of the water 0 milled soap.

The process will be further illustrated by the following specific examples. The parts are by weight:

Ewample 1-300 parts of corn oil of sapon ification number about 190 are put into a mixer. There is added and intimately admixed with the oil an amount of water which, together with that contained in. the powdered caustic soda, will be suflicient for dissolving the caustic soda. The amount'of water is in the neighborhood of 16.3 parts (in addition to that in the caustic soda), and the amount of caustic soda required for If the caustic soda is employed as 7 6% caustic containing 24% moisture, this moisture should container where the reaction will proceed and the emulsion will gradually begin and develop a great deal of heat, so much, in fact, that during the saponification or self-heating process, the newly formed soap reaches a temperature above the boiling point of water and rises considerably in the container.

After a certain time, the self-heating process stops and the soap recedes in the container. At this stage it may be shredded between water cooled iron rollsagainst which a shredding knife is closely set, and the shredded soap can then be packaged for shipment.

Theoretically, the soap made according to the above-example would have approximately the following composition, expressed in terms of the ingredients employed:

- P t Glycerides (corn oil) 300 8 Sodium oxide (Na O) 30.93 Water 26.06

The theoretical moisture content of a soap produced from these ingredients would be about 7.2%, but in practice it is somewhat less because of the self-heating and resulting evaporation of moisture during saponification.

Emample 2.300 parts of cocoanut oil are treated in a manner similar to that described in Example 1, except for the change in the amount of caustic soda required for the saponification, and the corresponding adjustment of the amount of water used.

It is also possible to replace part of the caustic soda with caustic potash in order to produce a product which will mill more smoothly and have a finer texture. It is also possible. and in some cases desirable, that the smallest dissolving ratio of water be used in dissolving the caustic soda before the mixing, that is. about 0.4 parts of water for 1 part of caustic soda. in which case the admixture will be of the caustic soda solution with the glycerides. A solution of caustic. alkali of alkali-water ratio of 1:0.4 may be obtained by taking advantage of the heat of solution of caustic alkali or by dissolving the alkali with the aid of heat. Such a solution is supersaturated with respect to ordinary room temperature.

It will thus be seen that the present in- I vention provides a simple and rapid method of forming soaps v of high soap and low water content in cake, chip or powder form, from fatty glycerides in which the ingredients can be mixed cold, and the reaction carried rapidly to completion with selfheating by the heat of saponification. 1t will further be seen that the process results directly in the production of complete-' ly saponified and relatively dry soap from low titre glycerides, with only a low or minimum moisture content, which can be directly converted into a merchantable form, for example, by rapid chilling on cooling rolls. Such soaps are firm, durable. less subject to hydrolysis and therefore not as likely to turn rancid as soaps of high moisture content made by the common methods of manufacture above referred to. v The process presents many advantages, giving a marketable soap in a short period of time, with saving of time, machinery, labor, heat, factory space, etc. 5

Different glycerides can be used formaking soaps according to the present process, and such g cerides may contain varylng percentages 0 free fatty acid. The process can also be varied in the amountsand proportions of the ingredients employed without departing from the spirit and scope of the invention.

I claim: 1. A process for the manufacture of soap with caustic alkali, which comprises admixing with the fatty materials a iven weight of caustic alkali and a limited amount of water weighing not more than theweight of said caustic alkali, emulsifying the resulting mixture, and causin the saponification'to take place under seli content.

2. A process for the manufacture of soap,

which'comprises forminga supersaturated causing the saponi cation to take place wit substantial completeness and under selfneration of heat to produce directly a finis ed soap'produ'ct .of low. water content.

3. A process for the manufacture of soap,

which comprises admixing with the fatty materials a given weight of causticalkali' and a limited. amount of water weighing not more than the weight of said caustic alkali, andbringing about intimate admixture thereof with the fatty material, and causin the saponification totakeplace under se f-genereneration of heat to produce. directly a fini ed soap of low water ation of heat to produce directly a finished