NO872717L - TRANSPARENT SOAP. - Google Patents

Description

The invention relates to a transparent soap mixture. Transparent soap, especially transparent toilet soap, is a well-known product. However, the production of transparent soap was complicated and involved expensive techniques such as mixing with high-shear mixers or e.g. addition of alcohol as a solvent for the soap. It has also often been necessary to introduce significant amounts of special components such as resin fatty acid soap, lanolin or the like.

A recent development in this field is indicated in GB-A-2,126,603 (Colgate Palmolive Co.) where lanolin (fatty acids) is incorporated into the soap composition and where, as shown in the examples, a mixture of tallow fat and coconut oil soap was prepared by classical way by boiling, to which the other ingredients, e.g. lanolin (fatty acid), possibly polyol etc. are added. Afterwards, therefore, is added to this soap material, which contains approx. 0.5% sodium chloride as well as glycerol, lanolin (fatty acid) etc. The sodium chloride present serves to salt out the soap and also brings the required hardness to the soap tablet to be made. In the description of the said British patent, it is also coincidentally mentioned, on page 6, line 29, that the soap can also be produced by continuous saponification of fatty acid, after which the additional components, such as e.g. lanolin, is introduced.

For simple processing according to the British patent, it would be desirable to feed all components directly into a device that causes direct saponification of fatty acids, but then a complication occurs that the lanolin is saponified, which destroys its activity.

The invention now provides a transparent soap composition which can be prepared, in a simple manner, by direct saponification of fatty acid, and this material differs from that described in British Patent Specification (GB-A-) 2,126,603 in that there is no lanolin (fatty acid) present and that the amount of sodium chloride is less than 0.2%, while the soap tablet produced from it has excellent transparency and e.g. is also sufficiently hard and has excellent foaming characteristics.

Accordingly, the invention provides a transparent soap with the following composition:

A: 55-79.5% by weight alkali metal or tert.-amine soap of

a fatty acid mixture consisting of:

90-70% by weight, preferably 85-70% by weight, of Ci6-C22 - fatty acids and

10-30% by weight, preferably 15-30% by weight, of C 10 -C 14 fatty acids;

B: 7-20% by weight of a thermostable polyol, i.e. a polyol

which does not discolor appreciably at 150°C;

C: 0.5-7.5% by weight free C10-C22 fatty acids;

D: 12-20 wt% water;

E: less than 0.2 wt% NaCl;

F: up to 2% of common components such as perfume,

dye, stabilizer, etc.

The soap mixture is preferably as follows:

A: 64-78%

B: 8-15%

C: 2-5%

D: up to 16%, preferably at least 12%

E: less than 0.1% (by weight) NaCl.

Although transparent soap, as a rule, contains potassium and/or triethanolamine soap, according to the present invention excellent results have already been obtained with predominantly or even exclusively sodium soap.

Coconut fatty acids or palm kernel fatty acids are normally used as Ci 0-Ci 4 fatty acids; as Ci 6-C22 fatty acids (saturated or unsaturated), tallow and/or palm oil fatty acids are very suitable, and these are advantageously partially replaced so that they contain up to 40% branched monocarboxylic acids. Suitable branched monocarboxylic acids are conveniently obtained as a by-product from the polymerization of unsaturated fatty acids. The branched monocarboxylic acids have short side chains (C1-C3) which are distributed over the carbon chain with a statistical preference for the central carbon atoms.

In the first place, sugar alcohols, e.g. sorbitol, mannitol, and so-called (poly)glycols derived from C2-C3 glycols having a molecular weight between 62 and 1200, as thermostable polyol; also other C3-Ce polyols containing 3-6 hydroxyl groups, polyols such as trimethylol propane, trimethylol ethane, glycerol, can be used.

An unsaponified fatty acid starting material, C10-C22 fatty acids, especially C10-C14 fatty acids, is particularly suitable. They can be added as such, but the saponification can also be carried out with a small amount of alkali metal hydroxide. The saponification takes place at temperatures of 20-160°C and at atmospheric pressure or superatmospheric pressure. The saponification can take place in an autoclave operated atmospherically or under pressure, or in a unit specially designed for saponification. As far as the hydroxide is concerned, it is preferable that sodium hydroxide is used, mainly or even exclusively. Adding potassium hydroxide gives no or little improvement, and in any case increases the price of the product. As common components, perfume, stabilizers and dyes must be considered. These ingredients should be chosen carefully, as they can cause opacity. However, suitable components for transparent soaps are already known from the prior art.

The present invention also provides a simple method for the production of transparent soaps, in which a fatty acid mixture of Ci 6-Ci 8 - and Ci 0-Ci 4 fatty acids and possibly other components in a suitable ratio to each other is saponified, completely or not completely, and after adding the other components B and C as defined above, it is dried to a water content of 12-20%, and the material thus obtained is processed, preferably with a standard soap processing unit, into transparent soap tablets. This equipment consists, for example, of of a mixer in which the perfume and dye are mixed with the soap granules, a refiner plodder and a vacuum plodder, in which, at the outlet, an extruded bar of soap is formed which is cut into suitable pieces and punched to

pills.

Example 1

2000 g of a mixture consisting of 80% tallow fatty acids (mainly consisting of approx. 24% palmitic acid, 20% stearic acid, 2% myristic acid and 40% oleic acid and homologues thereof) and 20% coconut fatty acids (mainly consisting of approx. 5%

capric acid, 50% lauric acid, 20% myristic acid, 11% palmitic acid and 10% oleic acid) were mixed and heated to 60°C. Then this mixture was saponified at 100°C by adding to it 1105 g of aqueous sodium hydroxide (27.6% solution in water) in an autoclave. After 10 minutes, 464 g of sorbitol solution (70% in water), 75 g of technically pure lauric acid (93% pure), 42 g of polyethylene glycol with an average molecular weight (M) of 400 and 12.5 ml of an aqueous solution of the Na salt of ethane-1-hydroxy-1,1-diphosphonic acid (EHDP) (30% in water) was added to this so-called "unmixed

soap". After thorough mixing of these components, the whole mixture was dried to a water content of 16%. The NaCl content was less than 0.01% (mainly from the technical grade sodium hydroxide), the free fatty acid content 5.3%. After processing to noodles, the visual transparency thereof was good. The noodles were fed into a plodder; a continuous bar was obtained, which was cut and punched to give soap tablets. Such an uncolored soap tablet 2 cm thick absorbed only 40% of a white light beam .

Example II

Analogously to what is described in Example I, a transparent soap was prepared in which the 42 g of polyglycol was replaced by 40 g of polyethylene glycol (M = 1000), and drying was carried out to a water content of 18%; The NaCl content was also below 0.01%. The transparency of this soap was somewhat better than for the above example.

Example III

In an analogous manner to what is described in example I, a transparent soap mixture was produced. Now, however, not 75 g of lauric acid of technical quality was added, but 42 g, and this resulted in transparent soap material with 0.01% NaCl and 3% free fatty acid content. In this case, the light absorption was significantly lower than that obtained according to Example I, namely 25%.

Example IV

According to a method analogous to that in example I, a fatty acid mixture consisting of 62% straight-chain Ci6-C22 - monocarboxylic (= fatty) acid, 22% by weight Ci0-Ci4 fatty acids and 16% by weight branched Cie-C22 -fatty acids (by-product from polymerization of fatty acids) saponified with 97% of the stoichiometric amount of sodium hydroxide. Further processing was identical to that in example I, but no fatty acid was added after the saponification. The NaCl content was below 0.01%; the light absorption was 20%.

Claims (10)

1. Transparent soap mixture, characterized in that it contains the following ingredients: A: 55-79.5% by weight alkali metal tert.-amine soap of a fatty acid mixture consisting of 90-70% by weight Ci6 -C22 fatty acids and 10-30% by weight of C10-C14 fatty acids; B: 7-20% by weight of a thermostable polyol; C: 0.5-7.5% by weight of free Ci 0 - Cz 2 fatty acids; D: 12-20 wt% water; E: less than 0.2 wt% NaCl; F: up to 2% of conventional components such as perfume, dye, stabilizer, etc. 2. Mixture as specified in claim 1, characterized in that the percentages are: A: 64-78% B: 8-15% C: 2-5% D: 12-16% E: less than 0.1% (by weight) of NaCl. 3. Mixture as stated in claim 1 or 2, characterized in that the soap contains sodium soap. 4. Mixture as stated in any one of claims 1 to 3, characterized in that the C 6 -C 22 fatty acid groups comprise up to 40% by weight of branched monocarboxylic acids. 5. Mixture as stated in any one of claims 1 to 3, characterized in that the soap also comprises triethanolamine soap. 6. Mixture as stated in any one of claims 1 to 5, characterized in that it contains 0.01-2% by weight of ethane-1-hydroxy-1,1-diphosphonic acid or a salt thereof. 7. Mixture as stated in any one of claims 1 to 6, characterized in that the polyol comprises a sugar alcohol. 8. Mixture as stated in any one of claims 1 to 7, characterized in that the polyol component comprises sorbitol. 9. Mixtures as stated in any of claims 1 to 8, characterized in that the polyol component comprises a glycol polyether having a molecular weight of between 200 and 600. 10. Process for producing a transparent soap mixture as stated in any one of claims 1 to 9, characterized in that a fatty acid mixture of Ci 6-Ci 8 - and Cio-Ci 4 fatty acids is saponified, completely or not completely, and after addition of the other components B and possibly C, it is dried to a water content of 12-20% and the material obtained is processed in a manner known per se with standard soap processing equipment into transparent soap tablets.