US1377843A - Soap - Google Patents

Description

LEONARD MERRITT LIDDLE, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR I0 ANDREW JEEGJENS COMPANY, 0F CINCINNATI, OHIG, A GGRPORATION OI? Patented ay Ml, Idfill.

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11,377 @413 Specification of Letters Patent.

Ito Drawing.

To all whom it may concern.

Be it known that l, LEONARD M. LIDDLE, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny, State oilennsylvania, have invented certain new and useful Improvements in Soa and I do hereby declare the following to a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in the manufacture of soap which is neutral or nearly neutral or even acid or superfatted in character and which contains an alkali metal salt of a weak organic acid of low molecular weight, for example, sodium or potassium acetate or'lactate.

The present invention is based upon the discovery that increased hardness or improved detergent properties, or both increased hardness and improved detergent properties, can be imparted to soap by the incorporation therein of an alkaline metal salt of one of the lower alifatic acids; and that such salts are also-advantageous as a filling for making filled Soap.

It is well known that not ever oil and fat will yield a soap fulfilling t edemands made upon it for household, toilet and manufacturers purposes;,a'nd it is customary, in the soap-making art, to blend the diiferent oils or fats available in such a manner as to roduce a soap which is most suitable for t e intended urpose. In general oils and fats of low titer give soft soaps, and hard fats of high titer give hard soaps; and it is common practice to blend oils andfats, depending upon the titers of the dif ferent raw materials, to ive a" composite mixture having the desire titer and which will give asoap of the proper hardness.

According to the present invention, oils and fats which are not themselves adapted to give a soap of proper hardnessmay have the proper degree of hardness imparted thereto without the admixture of hard fats and without the incorporation therewith of strong alkaline substance such as soda asli,

borax or sodium silicate.

In the manufacture of soap from natural oils and fats by means of caustic soda, it is customary to use an excess of soda in order Application filed July 7, 1919. Serial. No. 309,080.

to bring about complete saponification of the neutral fat or oil. As a result, there is an excess of caustic alkali present in the soap at the end of the soap-making reaction.

In order to remove as much as possible of this excess alkali, it is customary to salt out the soap and separate the soap curd from the aqueous layer containing the salt, glycerin and excess caustic soda, and to retreat the soap curd by boiling it up with fresh amounts of water, and again salting it out to separate further amounts of alkali therefrom. Nevertheless, the finished soap produced in this way will usuall still contain a small amount of excess alkali, and even the highest grades of soap upon the market will usually contain small amounts of this excess alkali. This small amount of alkali may not be objectionable for many purposes,

the soap varying-amounts of alkali salts,

such as soda ash, borax or sodium silicate. llhese salts, however, have a strong alkaline reaction and the soap containing them is injurious to sensitive skins and to delicate silk and woolen fabrics. According to the .present invention, the presence. of such alkaline reagents is avoided, and the soap is made of a neutral or nearly neutral character, while itis, nevertheless, given improved detergent and other propertles, comparable with the properties of soap containing the strong alkaline salts above referred to, without the objectionable alkalinity of such soap.

According to the present invention there is incorporated with the soap, at a suitable stage of the soap-making process, asufiicient amount of asalt of one of the lower fatty acids, such as sodium acetate or sodium lactate, to im art to the soap the desired properties, suc as increased hardness or improved detergent properties or to rovide the soap with a suitable filling. T e soap with which such alkaline metal salts of'the lower alifatic acids are-compounded, is itself alkali is unobjectionable for many purposes,

but the soap may even be freed from this slight excess of alkali, according to the present invention, so that it will be neutral. The soap may also be of an acid character,

a due to the presence of a slight excess of fatty acids.

The addition and incorporation of the sodium acetate or lactate, or like salt, will usually be effected after the soap-making process has been nearly completed. Thus, in the usual process of making finished soap, the sodium acetate may be incorporated with the soa during the usual crutching operation, a ter the soap has been freed from the excess alkali, and after it has been permitted to stand for the separation therefrom of the nigre. The sodium acetate may thus be added to the finished soap in the soap crutcher, together with a small amount of water, or with varying amounts of water, depending upon the amount still present in the soap and the amount which it may be desired to incorporate in the finished soap. The addition of the sodium acetate makes possible the incorporation of a somewhat increased amount of water when this is desirable. The incor poration of the sodium acetate will also serve to increase the hardness of the resulting soap, so that soaps of the desired hardness can thus be made from starting materials which, without the addition of the sodium acptate, would give a soap objectionably so t.

In the common soap-making process, as above stated, varying amounts of excess alkali will usually be present in the finished soap. In transparent soap or in soaps made by the cold process, if precautions are not taken to avoid excess of alkali in the finished soap, a considerable amount of alkali may be present therein. This excess alkali may, with advantage, according to the present invention, be neutralized by adding thereto acetic acid in amounts corresponding to the excess alkali, so. that it will combine there- 'with and form the alkali metal acetate, for

example, sodium acetate, where caustic soda is used as the alkali in the soap-making process. This method of incorporating sodium acetate with the soap has the added advantage of reducing or entirely removing the excess alkali, so that the finished soap is neutral in character.

For transparent soaps, it is common to use the finest grades of soap material and pure strong lye and to add alcohol at the amount ofsodium acetate is not too large, and the detergent roperties of the soap will can be readily made to harden by the addition of a small amount of sodium acetate,

end of the saponification and leave the glycerin with the finished soap, so that the. finished soap will remain alkaline in character. This excess alkali can with advantage be left in the soap and neutralized therein by the addition of sufiicient acetic acid in the manner above referred to, so that the transparent soap will retain all of its usual ingredients, but will have its excess alkali neutralized by the added acetic acid, so that the soap will be given improved roperties, due to the sodium acetate. This sodium acetate will increase the hardness of the soap without destroying its transparency, if the at the same time e improved. For slight hardening of transparent soap one or two per cent. of sodium acetate or sodium lactate will have an appreciable hardening effect. This amount, however, maybe somewhat increased to increase. the hardness or the deter ent properties.

transparent soap may thus be made from a mixture of about 50 per cent. of tallow, 30 per cent. of cocoanut oil and 20 per cent. of castor oil. If to,o much water is added during the soap-making process, the resulting soap will not harden or set, but it and the resulting soap will still be of a transparent character and retain as usual its content of glycerin and the added alcohol.

In general, I' reg ard sodium lactate as more advantageous for use in transparent soap, for the reason that it is less likely to crystallize out, and apparently has more valuable properties in promoting the transparency. I have found soap containing sodium lactate to be more transparent than soaps containing equal quantities of sodium acetate.

In the manufacture of soap powders, it is customary to use a relatively hard fat so that the resulting soap powder will be hard enough without requiring added hardness to be imparted thereto. The compounding or incorporating therewith of sodium acetate will, nevertheless, increase the detergent 115 power of the soap powder. Moreover, a softer fat, or a fat of lower titer can be used in making the soap powder, and increased hardness can be imparted thereto by the addition and incorporation of sodium acetate.

acetate in varying portions up to as much as 35 per cent. or more of sodium acetate and 65 per cent. or less of pure soap.

The soap can be made in other forms than the form of soap powder; for example, in the form of flakes, by incorporating the sodium acetate or a solution thereof with the soap prior to the flaking operation' In the manufacture of soap it is common to add varying amounts of rosin, so that rosin soaps are present in the final soap products. Rosin soaps frequently become soft and runny, and may require special.

treatment to overcome this tendency. According to the present invention such soaps can be readily hardened, and their detergent property at the same time increased, by adding a sufficient amount of sodium acetate, or other suitable salt, to give the desired hardness.

The present invention also provides an improved means for filling soap and for making filled soap, where such soaps are desired. The sodium acetate, for example, can be added in a solution of suitable strength and in sufficient amounts' in the manufacture of liquid soap, such as is used, for example, for shampooing and in liquid soap dispensers, it is common to add alkali'salts having a strong alkali reaction, for example, soda ash, borax or sodium silicate. Such alkali salts increase the latherin'g properties of the liquid soap, but they are objectionable because of their strongly alkaline reaction, and if present in any considerable amount, may result in an objectionable dryness of the skin or of the hair brushed or shampooed therewith. According to the present invention, such objectionable alkalinity is avoided, and liquid soaps are, nevertheless, given improved detel-gent and lathering properties, while still retaining them of a neutral or nearly neutral or even slightly acid character. The liquid soaps of the present invention are thus of particular value for use in shampooing and in liquid soap dispensers. llnasmuch as the addition of sodium acetate or like salt will serve to harden the soap, it may be necessary to add further amounts of water to prevent its solidification. Even concentrated solutions of the li uid'soap can, nevertheless, be freely used wlthout injury to even tender skins or to delicate fabrics.

The amount of sodium acetate or lactate can be varied within rather wide limits. In some soaps. where a slight hardening is desired,as little as one or two per cent of sodium acetate will materially assist in the hardening. For many purposes, however,

an addition of as much as five to ten per.

cent. or more of sodium may be desirable. If the soap without the addition of the sodium acetate would be objectionably mushy or slimy, a few per cent. of the sodium acetate will usually suffice to convert the material into a soap of the desired hardness. Where the sodium acetate is to be added as a filling or to increase the detergent power, as in laundry soaps and soap powders, as much as thirty per cent. or more may be added to the soap composition. The sodium acetate or lactate or other salt can be added in a drystate, as in the production of a soap or washing powder by grinding the dry sodium acetate with the soap, or where the soap already contains the desired amount of water. It can also be added in the form of a solution of varying strength. A solution containing about thirty or forty per cent. of sodium acetate will have an efi'ective hardening action upon the soap to which it is added. In the production of liquid soap, the water which may be added as a solvent of sodium acetate or otherwise I should be suflicient to keep the amount of sodium acetate added from hardening or solidifying the soap, and thereby preventing it from remaining in a liquid form.

In general, sodium salts of the lower alif atic acids, such as sodium acetate or lactate, should be added to soda soap, and potassium salts should be added to potash soap. Thus, for example, potassium acetate, or other potassium salts, should be added to a high grade potash soap, such as a potash shaving soap, and similarly sodium acetate or other sodium salt should be added to the common soda soap, so that the alkali metal of the added salt and of the soap itself will be the same.

The soap compositions of the present invention, can, of course, be compounded with other ingredients, such as perfume or coloring matter, or ingredients which will adapt the soap for special purposes. There may thus be compounded with the soap, material such as chalk, barytes, sand and the like, which will serve to adapt the..soap as a scouring soap or naphtha, petroleum or tar oils, may be incorporated with the soap, to form naphtha soap, petroleum soap, or tar soap.

Inasmuch as the alkali metal salts of the lower fatty acids which are employed in the soap compositions of the present invention are free from any objectionable alkaline reaction, the resulting soaps are well adapted for use for various purposes, where the pres ence of alkali is objectionable. They-are detergent properties to soaps containing corresponding amounts of strong alkalies, such as soda ash or sodium silicate, while itis free from the objectionable alkaline properties of such soaps.

The alkalimetal salts of the lower alifatic acids are salts of a strong base and of a weak organic acid of low molecular weight. They are, nevertheless, neutral in reaction, in the sense that they do not have any such alkaline reaction as do inorganic salts, such as soda ash, borax or sodium silicate. In fact, these alkali metal salts of .the lower alifatic acids themselves partake of the nature of soaps, inasmuch as the soaps are likewise alkali metal salts of fatty acids. The soaps themselves are, however, distinguished from these alkali metal salts of the lower alifatic acids by the fact that they are made from higher fatty acids having a characteristic greasiness, and a relatively high molecular weight; whereas, the lower fatty acids are free from the characteristic greasiness of the higher fatty acids, and their salts are free from the characteristic soap consistency and solutions of the salts from the colloidal character of strong soap solutions.

From the foregoing descnption it will be evident that the present invention is of general application to the soap-making art and that' soaps of various kinds and for various purposes may be made in accordance therewith. Soa s can thus be made in various forms, suc as in the form of soap powder or flakes, or in cake or liquid form, or in the form of paste, such as tooth paste, etc.

The soaps maybe such as are commonly used for household or'toilet' purposes, or they may be such as are used in laundries or in other manufacturing plants where treatment with soaps of various kinds is required,

as in the treatment of textiles and the like.

The soaps of the present invention, irrespective of the purpose for which they are to be used, present the characteristic advantages of freedom from any appreciable amount of free alkali and improved detergent properties. In addition the soap may have an increased degree of hardness imparted thereto 1 by the added sodium acetate or other salt, or

the soaps may be filled with such salt. The present invention, accordingly, includes soaps of. various kinds which contain in an appreciable amount sodium acetate or lactate or salts of a similar character, irrespective of whether the salts are added to impart hardness or to improve the detergent properties, or as a filler, or for two or more of these purposes.

I claim:

1. A solid soap composition of a neutral or nearly neutral character, comprising soap and an alkali metal salt of a lower alifatic filled soap having as a filling therefor an alkali metal salt of a, lower alifatic acid. 1

5. A soap powder comprising soap and an alkali metal salt of a lower alifatic acid, said soap powder being free from any appreciable excess of alkali or compounds of a strong alkaline reaction.

6. A solid soap composition comprising substantially pure neutral or nearly neutral soap and alkali metal salt of a lower alifatic acid.

7. A transparent solid soap of a neutral or nearly neutral character, containing an alkali metal salt of a lower alifatic acid.

8. Soap compositions of the character referred to in the preceding claims in which sodium acetate is the alkali metal salt.

In testimony whereof I aflix my signature.

LEONARD MERRITT LIDDLE.; Witnesses i P. F. 'EIQHENLAUB, F. H. Anusosu.