US1989312A - Laundry sour composition and method - Google Patents

Description

Patented Jan. 2i9, 1 935 7 I 9 "Lamar soon iGerber, Anniston, Ala, assignor to Swann Research, Incorporated, a corporation of Alabama I :No Drawing. Application Serial NO. 673,313

This invenion relates to a new laundry sour and further to a method by which improved results may be obtained in the cleaning of textile materials.- i

Previous advances in the art of souring textile materials in the laundry have indicated the desirability of utilizing'ammonium salts such, for example, as the chloride and sulphate; These salts react with the sodium carbonate in the clothes in accordancewith well known chemical principles, to form ammonia and carbon dioxide, both of which are gases, and a sodium salt which is harmless and easily removed substance. Various other materials, such as organic or mineral acids, among the latter being mentioned muriatic, sulphuric and phosphoric acids, have been proposed as sours.

The objection, however, to the ammonium salts already disclosed is that salts such as the chloride and sulphate, if not completely decomposed or otherwise removed from the textile fibres, easily decompose due to the action of light or heat and leave a strong mineral acid residue on the fibre which is known to cause serious tendering of the fabric. The difficulty of completely removing even very soluble salts from textile fabrics, due to the absorption effect, is too well know to require further comment.

The objection to such free acids as'muriatic, sulphuric or phosphoric is similar to that above mentioned in the case of the cited ammonium salts. As far as I am aware, such mineral acid sours have never been seriously considered by the laundry industry.

I have now found that the advantages of the ammonium salts in regard to reactivity with alkalies may be realized by utilizing monoammonium phosphate, either as such or combined with sours of the class of sodium acid fluoride or ammonium silicofluoride. -Particular sours for various classes of work will presently be described.

After the usual washing and bleaching operation, it is customary to rinse out the residual alkali, bleach and antichlor if one is used, as completely as possible. As is well known, however, in commercial laundries such rinse does not completely remove the alkali, hence inorder to develop whiteness it is customary to utilize a sour with the object of destroying any alkalinity present. Such an operation is attended by a certain amount of risk to the fabrics treated, and successful manipulation requires a certain modicum of practical care as well as scientific control of this operation. For this reason a considerable amount ofthought has been given to this operation, as attested to by the relatively large number of patents granted in this field in recent years;

While the "theoretical object of the sour is :to arrive at a condition ofneutrality, practically? because of the difficulty of achieving a complete rinse-4t is the customary practice to oversour somewhat. To this end it is customary to sour to the point'where the eflluent from the extractor has'a pH in the range of 4.5 to 5.0. Under these conditions, due to the absorption effect, the pH of the clothes is somewhat higher. A further reason for over-souring is the peculiar shape of the carbonate neutralization curve which, because of the presence of carbonic acid, shows complete neutralization only at a pH between 4 and 5.

By employing monoammonium phosphate, either as such or in certain preferred combine. tions, in the souring bath, I am enabled to sour to this preferred degreewithout'leaying an ob? jectionably strong acid in the fabric,; and hence without'tendering the goods.

For the general souring of white work, I prefer a composition such as the following:-

Parts Sodium acid fluoride 50, Ammonium silico fluoride 30 Monoammonium phosphate In this composition the sodium acid fluoride is used as the major constituent to give the desired acid intensity, while the ammonium silico fluoride increases the total acidity to the desired level; The monoammonium phosphate is present to minimize the danger of over-souring and to maintain a sufficiently high acidity to prevent deposition of silica by neutralization of the silico fluoride. With such a sour it is possible to carry the acidity to a level where it is effective for ironstain removal.

A sour for colored work may have the following composition:

Parts Ammonium silico fluoride 50 Salt (NaCl) 20 Monoammonium phosphate 30 In this formula ammonium silico fluoride supplies the major acidity, the salt being added to prevent bleeding and fading of dyestuffs. The monoammonium phosphate is present up to 30% or more to supply a greater percentage of total acidity at a higher and safer level.

The incorporation of monoammonium phosphate in the souring composition or directly in the bath, due to its comparatively high pH,

will iurnish a material which will not react until all or substantially all of the more acid salts have been neutralized. At this point the ammonium phosphate will come into play to carefully adjust the acidity of the final sour bath; and completely prevent the danger of over-souring. Unreacted sour will be in the form of a safe, mildly acid salt that will not cause loss of tensile strength.

Insofar as silica deposition from completely neutralized silico fluorides is concerned, it has been determined that this is not serious if the acidity is maintained below a pH of 4.5 to 5.0. Monoammonium phosphate will then prevent deposition by giving a pH in the neighborhood of 5.0.

In a sour for colored work the proportion of monoammonium phosphate may be increased advantageously. The alkalinity of wash solutions usedon colored work is lower and a genin water solutions exhibited by these salts.-

Other sours may also be incorporated in the composition for particular purposes.

Although I have described with great particularity certain specific embodiments of my invention, it should be understood that it is not so limited but is susceptible to various changes and modifications, without departing from the spirit thereof, and I desire that only such limitations be placed thereupon as may be required by the prior art or as are specifically set forth in the appended claims.

I claim:

1 In laundering, the method which includes subjecting the fabrics to a bath containing soap and an alkali and thereafter to a bath containing monoammonium phosphate.

2. In laundering, the method which includes subjecting the fabrics to a bath comprising an alkaline detergent and thereafter to a bath containing monoammonium phosphate.

3. In laundering, the method which includes subjecting the fabrics to a bath comprising an alkaline detergent, rinsing said fabrics and thereaftersubjecting said fabrics to a sour comprising monoammonium phosphate.

4. A laundry sour comprising water-soluble compounds of fluorine and monoammonium phosphate.

5. A laundry sour for white. work comprising sodium acid fluoride 50 parts, ammonium silico fluoride30 parts, and monoammonium phosphate 20 parts.

6. A laundry sour for colored work comprising ammonium silico fluoride 50 parts, salt 20 parts, and monoammonium phosphate 30 parts.

ARTHUR B. GERBER.