US1743054A - Process for rendering harmless substances which cause hardness in soaping and washing operations and for the production of means suitable therefor - Google Patents

Description

Patented Jan. 7, 1930 UNITED STATES PATENT OFFICE GUSTAV ULLMANN, OF VIENNA, AUSTRIA PROCESS FOR RENDERING HARMLESS SUBSTANCES WHICH CAUSE HARDNESS IN SOAP- ING AND WASHING OPERATIONS AND FOR THE PRODUCTION OF MEANS SUITABLE THEREFOR No Drawing. Application filed February 11, 1926, Serial No. 87,682, and in Austria March 6, 1925.

For many purposes, particularly in commercial processes, and also in domestic washing and other cleansing operations, where soap is used, the presence of substances which cause hardness or salts such as those contained in sea water and alkali salts, bicarbonates, and sulphate of sodium, which are often contained in the natural water employed causes great inconvenience. There are indeed methods of artificially softening such waters (e. g. the lime soda method, the Permutit method, etc.) but these methods require special apparatus or constant supervision in operation, and it is an economic impossibility to produce or keep in stock in the necessary and frequently very large quantity water purified in this way. In the textile trade, for example, it is very frequently necessary to cleanse the goods by submitting them to the action of soap or to obtain other eifects by treating them 'with soap solutions, for example, in the milling or fulling operation, in

the developing of vat dyes by a subsequent hot soa ping operation, in the developing of dyes of the type of Griesheim red, in the scouring of silk, in the so-called boiling of bleached yarn, laces and fabrics, and in a great numher of other operations. Now it is perhaps possible to produce clean water in quantities sufficient to carry out the soap treatment as such, without difficulties due to the presence of substances which cause hardness, which substances are principally bicarbonates, sulphates, and chlorides and other salts of calcium and magnesium. But a washing operation must always follow the soap treatment in order to remove the soap or the impurities removed by it from the goods. This washing operation requires many times the volume of water required for the soap treatment and almost invariably natural water loaded with substances which cause hardness must be used for rinsing. In this washing operation, there-v owing to the large volume of rinsing water employed. The result of this is that the soap still contained in the goods is converted into lime soap and this latter gives the goods a harsh feeling, makes them sticky and brings about other well known troubles. Substances have been known for many years which, from a chemical standpoint, closely resemble true soaps and which form with the substances which cause hardness, such as lime or magnesium, Water soluble compounds which to a high degree are insensitive to salts and which are also distinguished by great moistening power and other desirable properties, There exists a large number of similar, although chemically different, products which contain sulphonated fatty acids and which may be derived from various fats and oils, resins and resin oils or mixtures of these substances. These products have been used in industry and exhibit the same properties in respect to substances which cause hardness and solutions of different salts, such as chlorides, carbonates, alkali sulphates. These products are known under various trade names, such as Monopol Soap, Oleonate R, Monol, etc. In the following description, for the sake of brevity, such soaps will be termed special soap or special soaps, whereas a soap containing about 60 per cent of fatty acid and alkali will be termed ordinary soap. It is known how to obviate the damage caused by such substances as cause hardness but the known bodies for that purpose have to be used in quantities which are not inconsiderably greater than is demanded by the chemical equation for the reaction between the substances which cause hardness and the fatty acids. However that the materially higher price of such substances possessing the aforesaid qualities makes their use in practice uneconomical, apart from the fact that soaps of the type mentioned are greatly inferior in lathering power to true soaps and lack certain other properties possessed by the true soaps. v

The surprising discovery has nowbeen made that the favourable action of these bodies resembling special soaps is fully manifested even when mixtures of ordinary soaps and compounds of this kind are used, in which however the special soaps added may be much less in quantity than the amounts prescribed by the law of stoichiometry. The particular special soap that is employed in-the present process of manufacturing and production of the present soap includes a well known soap which is of a gelatinous consistency'and consists in a completely sulphonized oleaginous matter composed o fats, oils, fatty acids or oleic acids, either separately or ointly, in which the remaining sulphuric acid has been separated and finally being perfectly saponified by a quantity of.alkali equivalent to the existing fatty acids, to free the produced soap from the fatty acids and the alkali. This particular type of soap was discovered and used for the same purpose that the present soap is now used, the present soap, however, requiring a lesser quantity of the gelatinous substance soap for the given quantity of water in which it is used. An example will explain this:

'Ewam-ple I .In a water of 12 degrees of hardness (German scale) goods are to be soaped', which when treated in chemically pure water or water artificially softened, or water obtained from the condensation of steam, would require the addition of l g. of soap containing 60'per cent of fatty acid. When the above mentioned water of 12 degrees of hardness is used the same result will be obtained if 3 g. of soap and 0.6 g. of'the product known under the trade name Oleonate or of that known as Monol to 1 litre of water be used. Such a combination produces a soap having a different action toward lime and salts and contains about 62 per cent of fatty acids and 4.3 per cent of S0 The economy in the consumption of soap obtained in the foregoing example will be clear by the following calculation. CaO has the molecular weight 56 and requires 2 molecules of fatty acid havin an avera e molecular weight of 282 (C 0 fine litre of water of 12 degrees of hardness contain g. CaO and theserequire 1.2 g. of fatty acid, corresponding to 2 g; of soap or of the aforesaidOleonate R or Monol, containing 62% of fatty acid. In other words the lime contained in one litre of water would bind stoichiometrically 2 g. of soap and the lime soap formed would be precipitated, whereas in the above example only 0.6 g. of Oleonate is consumed, that is to say, 30% of the stoichiometric quantity. Besides there is no loss in soap because the small amount of undissolved particles is innocuous.

In this method it is possible, however, to proceed to a limit at which separation from the soap takes place, owing to the action of the substances which cause hardness. This separation, however, differs very materially from the well known lime soap, etc., which is sticky and separates in the form of lumps.

It is in the form of a substance which can be easily rubbed up in the hand and which always tends to produce lather. It entirely lacks the stickiness of lime soap and can easily be washed out of the goods, whereas lime soap can only be removed by chemical action, that is to say, by decomposition with acid and subsequent treatment with soap.

Another discovery is that, when working according to this method, the amount'of soap can be reduced to such an extent that, even in the case of hard waters, a smaller'amount of soap is required than when working with chemically pure water or water artificially softened, or water obtained by the condensa tion of steam. The amounts of special soap which have to be added in order to secure the result according to the method. described are, as stated above, not more than one third of the amount equivalent to the substances which cause hardness. It must therefore be assumed that the body formed between the lime soap and the special soap takes part directly in the process or operation of washing.

Explanation of the whole method and the likewise fortuitous and surprising phenomenon above referred to is supplied by the principles of colloidal chemistry, the process herein referred to being based entirely on colloidal principles and systematically scientific investigation. What may be assumed as known is that any separation of colloids, of which soap solutions may be regarded as specific representatives, has as a paramount condition the fact that the dispersion is reduced to a certain degree. When substances which cause hardness,-such for example as lime salts, act on soap this degree of dispersion is arrived at very quickly. The small particles coalesce to form large ones until a. certain maximum is reached'and separation follows accordingly. Whereas this separation takes place very easily when substances which cause hardness act on soap, owing to the increase in the size of the particles, special soaps always yield onlv particles of a considerably finer degree of dispersion, in which case there is no cause, according to the laws of colloidal chemistry, for any separation to take place. An investigation was therefore made to ascertain whether it would be possible to so influence'the size oftheparticles. of the body formed by the substances which cause hardness plus fatty acid, by the addition of special soap and whether the dispersion of this mixture could be raised to a maximum so as to prevent the caking together of the ordinary lime soaps and their precipitation or their separation in the deleterious sticky form. It has actually been found that this result can be obtained and furthermore (which is entirely in accordance with colloidal chemical experience) not with the same roportions in the mixture as are demanded y the law of stoichiometry but with other due proportions than the latter .and such as are far below the proportions by Weight laid down by the law of stoichiometry.

These experiences are fully supported by measurements which have been made under the ultramicroscope. In these measurements it was found, under certain conditions, which were the same in all cases of a comparative investigation, that, if solutions of soap in hard water and of soap in distilled water be taken as the extreme points, the number of particles in hard water closely approaches that given by the solutions of soap in distilled Water with the mixtures of ordinary soap and special soap far below the stoichiometric limits. This phenomenon is exactly analogous to the peptization of colloids. Even comparatively small quantities of special soap act on the lime soap as peptizing agents. The said substances possess these powers, on the one hand, by virtue of their tendency to form complexes with the lime soap and, on the other hand, by virtue of their relationships to the solvent (and consequently hydration) which imparts stability to the colloidal system. The colloidal particles of lime soap are therefore prevented even by small quantities of the special soap with which they form complexes, from coalescing and separating, but even if separation docs take place on further dilution with hard water, the fine structure of the precipitate acquires a form which enables it to be washed away easily.

It is therefore in agreement with theory that, when such mixtures are used in practice, with hard water similar results ensue in soaping operations as occur when softened water is used. Furthermore, other extremely important advantages were discovered. The special soaps are distinguished by their high degree of dispersion and properties of penetrating the fibres and of difi'using osmotically, with extraordinary ease, into the interior of the fibre. Ordinary soap solutions, particularly lime soaps etc.. remain sticking to the outside of the fibres and are incapable of penetrating into the interior thereof. If the soap treatment be carried out with the hereinbefore described mixtures of ordinary soap and special soap, the latter apparently deposits itself in the interior of the fibres and, when the soap solution impregnating the goods is afterwards diluted in the washing operation, the ordinary soap solution or the precipitate deposited on the outside of the fibres is first washed off and the special soap which diffuses slowly out of the fibre is dissolved off therefrom. The special soap therefore forms a kind of protecting agent, so that the excess of lime and other substances which cause the hardness produced during the operation of washing by the addition of large volumes of water, is rendered incapa ble of depositing itself on the fibre in any which contain salts viz: the salts contained in sea water, and alkali salts, bicarbonatcs, and sulphate of sodium, which are often contained in natural Water. The process can therefore be used. with excellent results in soaping and washing operations which are carried out with sea water.

The remarks made above in connection with operations in textile industries apply also to other soaping operations, whether they be for industrial purposes or in connection with soap for cleaning purposes such, for example as toilet soaps, medicated soaps, shaving soaps, household soaps, etc. Since, as has been already stated, the process is suited for'soaping and washing operations which are carried out with water containing salts, it is therefore suitable-for soaping and wash mg operations which are carried out with sea water, where even a slight addition of the said special soap, in the sense of the above mentioned phenomena, prevents salting out to a great extent, or keeps the soap ina state of fine dispersion and gives the power to the soap to form lather, which secures very great advantages in comparison with the soaps at present available. The mixing of ordinary soap with special soap is well known, but when such mixtures have heretofore been used the endeavour was always made to effect the complete conversion of the insoluble soaps into solution, which requires great consumption of special soap and makes the process uneco'nomical. The discovery on which the present invention is based, namely that-of making the substances which cause hardness and the before-mentioned salts harmless, even with the addition of the said special soap, is that less special soap is required than what is demanded stoichiometrically, so that when the soap mixture is used separations take place which, however, do not exhibit the character of sticky metallic soaps. This discovery has opened up further applications of the present invention, in which its technological and economical advantages are manifested. Instead of introducing the ordinary soap and the special soap into the bath or washing water separately, as described above, toilet, shaving, washing and medicated soa s may be prepared which render the su stances which cause hardness and the before-mentioned salts contained in the water harmless. The same result is indeed achieved ifthe said special soap or the like be introduced into the bath or washing water in the same manner as hereinbefore described; it is however advantageous for the consumer to obtain the mixture ready prepared, as will be obvious from the following remarks.

In the manufacture of shaving soap, in order to increase its lathering power and softness to the skin, it is usual toadd an ordinarily high percentage of the necessary alkali in the form of expensive hydroxide or carbonate of potassium, the amount of which, when the process of this invention is used, can be considerably reduced in favour of the much cheaper sodium hydroxide or carbonate. Furthermore, whereas in order to ob- .tain a lather, it has been customary, as is well known, to incorporate an excess of fat with a shaving soap, when such a soap is made according to the present process, such addition of fat, which gives shaving soap a tendenc to turn rancid, may be omitted. The adc ition of the said special soap according to the present invention, in the production of shaving soaps also makes it possible to use cheaperkinds of fat, such as distilled bone grease, and in particular all kinds of distilled fatty acids, in the manufacture thereof, whereas hitherto soaps made on the above mentioned fat basis are particularly sensitive to the action of lime and of the before-mentioned salts and will scarcely produce a lather in even only semi-hard waters.

The same is true as to toilet soaps.. As is well known, soaps known as glycerine soap are on the market which originally contained a kind of colloidal solution of an alkali salt of a fatty acid in glycerine, (but more recently a similar one in alcohol) and which, on account of their transparency, are very popular. But such soaps, on the one hand, possess very little lathering power and, on the other hand, are not pleasant when used as toilet soaps, owing to the action on the skin of the alcohol which they contain. According to the present process, the addition of the said special soap to the glycerine soap gives the glycerine soap the softness and lathering power which, in its ordinary state, it lacks, without altering the appearance which renders it attractive and without the above described objectionable efi'ects. Further, the so called glycerine soap, manufactured according to the process herein described, does not exhibit the undesirable stickiness which the soaps prepared with .the addition of glycerine possess.

The coconut-oil soaps, made by the cold stirring process and mainlv used as toilet soaps, are liable to irritate the skin owing to the presence of an unavoidable excess of free alkali, but this can be considerably mitigated by the present process, quite a art from the fact that, in toilet soaps, and a so in shaving soaps etc., the avoidance of theformation of lime soap is specially important.

In milled toilet soaps, as is well known, the softness of the soap is often increased by the addition of lanoline or the like in small quantities. This addition, which is not always desirable, may be omitted when the present process is used, whereby the disadvantage which the lanoline has of imparting an undesirable stickiness to the toilet soap is eliminated.

Ewample II.--6O kg. of tallow and 40 kg. of bone grease are saponified with 60 kg. of caustic soda lye of 30 degrees B., in the well known way, salted out and boiled up. The mass is then allowed to settle, drawn off from the lye and the hot mass of soap crutched with from 4 to 6 kg. of the product known as Oleonate R or of that known as Monol. The soap is then allowed to solidify and further treated in the well known way.

The soaps produced by the method herein described exhibit, without difiering in appearce from the usual soaps of the same type, a particularly persistent power of lathering and emulsification for neutral fats, and consequently possess an excellent softness which hitherto has been unknown, protect 'the ma: terials on which they are used, are particularly economical in use, and possess a-surprising degree of cleansing power.

When mention is made in old publications, e. g. in the specification of United States Patent 585,347, of the use of bodies of the type of the special soap in admixture with ordinary soap in order to retard the deleterious action of the substances which cause hardness, nothing whatever is said about itsbeing possible to obtain such effects if the operation be carried out with quantities of theadded special soap which are far less than those required by the law of stoichiometry. Only the colloidal chemical researches of the most recent times have made it possible to devise a process of the kind herein described and only such researches'have provided both the scientific basis for such a purpose and also the explanation of the surprising reactions envolved.

A further improvement of the process herein described is obtained if the mixtures of ordinary soap and special soap above described be incorporated with substances which assist the favourable colloidal chemical action, that is to say, increase the degree of dispersion or, in other words, are capable of ensuring the stability of the suspension of acting as pep tizing agents. As such bodies the following .have proved of advantage: urea, mixtures of amino acids such as are obtained by the decomposition or breaking down of glutines, also soluble lactates, phosphates, borates, silicates and the like. These bodies are added in small quantities either to the mixture of soaps or to the washing water. Either method of carrying out the process is again suitable both for industrial and domestic washing operations, personal-cleansing etc.

Example Ill.-As in Example I, a water of 12 degrees of hardness (German scale) is to be used in which woven goods are to be washed. The washing operation is carried out with 3 g. of soap containing 60 per cent of fatty acid, 0.45 g. and 0.1 g. of urea to each litre of water. The urea ensures the stability of the suspension or acts as a peptizing agent.

Example I V.Like Example III. 0.08 g. of neutral sodium lactate is used as the added substance instead of urea.

E wample V.Like Example III. Instead of urea there is added 10 0. cm. of a solution which is obtained by the decomposition or breaking down of glutine in a 1% solution bythe action of a solution of normal lye containing 40 g. of NaOH to one liter of water in an autoclave for one hour at a pressure of three atmospheres.

Example Vl.-Like Example III. Instead of urea thereis added 0.06 g. disodium phosphate (Na PHO or of the equivalent quantity of borax or water glass.

What I claim is:

1. In a process of laundering in hard water; the method of rendering harmless the substances contained in said water and which cause hardness thereof, consisting in adding to the water and ordinary soap an amount of another soap which is insensitive to said substances and produced by saponifying sulphonated fats or the like in a proportion less than the quantity chemically equivalent to said substances contained in the water.

2. A method accordin to claim 1 wherein a small quantity of a sta ilizing or peptizing agent is added to the water and soap.

In testimony whereof I have hereunto set my hand.

GUSTAV ULLMANN.