Dioctyl sulfosuccinate compositions containing antifoaming agents

2,969,332

Patented Jan. 24, 1961

United States Patent Office

2,969,332

DIOCTYL SULFOSUCCINATE COMPOSITIONS CONTAINING ANTIFOAMING AGENTS ⁰

Edward B. Lawler and Kenneth D. Ballou, Charlotte, N.C., assignors to American Cyanamid Company, New York, N.Y., a corporation of Maine

No Drawing. Filed Feb. 5, 1957, Ser. No. 638,237

Claims. (Cl. 252—354)

This invention is directed to wetting and detergent com- 15 positions containing a dioctyl sulfosuccinate as the principal surfactant, together with one or more higher fatty acid antifoaming agents therefor and a solubilizing or dispersing agent. The invention provides wetting and detergent compositions which combine excellent wetting 20 power with good storage stability and a greatly reduced degree of foam development when used under conditions of strong agitation.

There are a number of industrial uses for wetting agents in which the development of foam is objection- 25 able and in which a non-foaming wetting composition is required. For example, in high speed textile process operations such as enzyme or acid desizing, wetting out cloth and other textiles prior to dyeing or printing and in other dyeing processes such as package dyeing or open 30 tub dyeing the development of foam is objectionable. In mechanical detergent processes such as in automatic dish washers and in many automatic home laundering machines the formation of excessive suds is likewise undesirable. . ³⁵

Low-foaming wetting formulations usually contain surfactants of relatively poor surface activity or . include water-immiscible components which interfere with their normal efficiency. It is a particular object of the present invention to provide wetting and detergent compo- 40 sitions wherein the active wetting agent is a water-soluble salt of one or more dioctyl sulfosuccinates, the most powerful wetting agents now available commercially. It is a further object to provide compositions wherein the foaming properties of these wetting agents are materially ₄₅reduced without, however, substantially decreasing their, wetting power and without scum formation.

The water-soluble dialkyl sulfosuccinates are well known wetting agents, being described in U.S. Patent No. 2,028,091. The various esters of this class which ₅₀are available commercially as wetting agents range from “Aerosol OT,” which is a sodium dioctyl sulfosuccinate, to “Aerosol IB,” which is the corresponding di-isobutyl ester. Both the wetting power and the foaming characteristics of these agents increase with their increasing 55 molecular weights; thus “Aerosol IB” and “Aerosol AY” (the diamyl ester) develop little.or no foam at the concentrations in water of 0.025-0.1% in which they are ordinarily used, whereas the corresponding dioctyl esters are strong foaming agents at these concentrations. θθ

We have found that the higher fatty acids, by which term we mean the saturated and unsaturated aliphatic monocarboxylic acids of 16 or more carbon atoms and preferably about 16-22 carbon atoms, are effective antifoaming agents for the dioctyl sulfosuccinate alkali metal ₆₅and ammonium salts, and that they will reduce both foam formation and foam stability without decreasing the wetting power of the surfactants to any considerable extent. Unfortunately, however, dispersions of the higher fatty acids in concentrated aqueous solutions or pastes of the wetting agents, such as those of from 25% to 75% solids that are sold commercially, are not storage-stable and tend to solidify during storage and shipment. Furthermore, the fatty acids tend to separate out when the concentrates are diluted with water and therefore develop excessive scum-formation under these conditions of use.

We have found, however, that these adverse effects of the higher fatty acids can be overcome by using, in conjunction therewith, their diethylene glycol monoesters. In other words, we have found that a mixture of an alkali metal or ammonium salt of a dioctyl sulfosuccinate with both a higher fatty acid and a monoester of a higher fatty acid with diethylene glycol will provide a composition which combines excellent wetting power and good detergency with good storage stability, low foam development and no scum formation. Our invention in its broadest aspects therefore consists in the provision of surfaceactive compositions containing these three essential components, with or without other ingredients as will hereinafter be more fully described.

Any higher fatty acid containing 16 or more carbon atoms may be used in preparing the compositions of our invention, either singly or in admixture. Saturated higher fatty acids and mixtures of fatty acids containing from 16 to 22 carbon atoms are sold commercially as stearic acid, hydrogenated fish oil fatty acids, hydrogenated cottonseed oil fatty acids and hydrogenated tallow fatty acids, and may be used. Unsaturated higher fatty acids such as oleic acid, linoleic acid and the like may also be employed. Tall oil fatty acids, the principal ingredients of which are oleic and linoleic acids, are both relatively cheap and commercially available, and are suitable. Any of these acids or acid mixtures may likewise be esterified with diethylene glycol to form monoesters suitable for use in practicing the invention.

The monoester of diethylene glycol with any fatty acid of 16 or more carbon atoms or any acid mixture, including particularly those enumerated above, may be employed. It is unnecessary to use the monbethylene glycol ester of the particular fatty acid which is to be added to the dioctyl sulfosuccinate as an antifoaming agent; however, it is usually preferable to do so for economic reasons. Thus, for example, a mixture of substantially equal quantities of stearic acid and diethylene glycol monostearate is easily prepared and has given excellent results in practice. Another preferred mixture is that of the monoester of ethylene glycol with tall oil fatty acids and the tall oil fatty acids themselves.

The dioctyl sulfosuccinate wetting agents of greatest commercial importance, with which the above-described mixtures are used, are the sodium di-(2-ethylhexyl) sulfosuccinate (“Aero'Ol OT”) and sodium di-n-octyl sulfosuccinate (“Aerosol OTN”). It will be evident, however, that other dioctyl sulfosuccinates of the same class such as the bis-esters of other octyl alcohols and the ammonium salts or the alkali metal salts other than the sodium salts, all of which present foaming problems, can be treated in accordance with the invention. . . ..

The quantities of the three principal ingredients may be varied through considerable ranges while retaining the advantages of the invention. The dioctyl sulfosuccinate, being the principal active ingredient, is usually but not necessarily present in preponderating amounts; ordinarily it constitutes at least 50% by weight of the solids present in the composition. From this minimum value it may range to as much as 95% by weight of the solids, the higher fatty acid and diethylene glycol ester constituting the balance. In other compositions part of the dioctyl sulfosuccinate may be replaced by other ingredients such as from 5 to 30% of its weight of an alkali metal benzoate, which increases the rate of solution of the ester in water. An alkali metal salt of a higher fatty acid, such as potassium oleate or stearate,

2,969,839 may also be present in amounts of 0.1-1.5% based on the weight of the solids in the composition.

The quantity of higher fatty acid may range from about 5% to 100% of the weight of the dioctyl sulfosuccinate, depending on the particular sulfosuccinate or sulfosuccinate mixture in the composition and the extent of foam reduction that is desired. When sodium di-(2ethylhexyl) sulfosuccinate is used as the surfactant a relatively small proportion of higher fatty acid, within the range of about 2.5% to 50% of the weight of the sulfosuccinate, is usually sufficient. The quantity of diethylene glycol monoester is ordinarily from about 25% to 200% of the weight of the fatty acid.

The wetting compositions of our invention may therefore be defined as consisting essentially of from about 50 to 95 parts by weight of the dioctyl sulfosuccinate constituent, which may be a single ester or a mixture of two or more dioctyl sulfosuccinates, together with from about 5 to 50 parts by weight of a mixture of one or more higher fatty acids and one or more diethylene glycol monoesters thereof, the weight ratio of the diethylene glycol monoester component to the fatty acid component being between about 1:4 and 2:1. In addition to these essential ingredients the composition may also of course contain water in any desired amounts and it may also contain a small proportion, usually less than 2% on the weight of the solids present, of an alkali metal salt of a higher fatty acid which assists in obtaining a smooth and uniform dispersion. Other ingredients such as sodium benzoate or other water-soluble salt of benzoic acid may also be present in minor amounts to improve the watersolubility of the dioctyl sulfosuccinate as noted above.

The invention will be further described and illustrated by the following specific examples. It should be understood, however, that although these examples may describe in detail certain particular compositions the invention in its broader aspects is not limited thereto.

EXAMPLE 1

Samples were prepared by adding higher fatty acids to “Aerosol OT-75%,” a commercial grade of sodium di-(2ethylhexyl) sulfosuccinate containing 75% active ingredient, 20% water and about 5% isopropanol. The wetting agent was heated above 70° C. and the acids were dispersed by agitation. Portions of the samples were then diluted with water to 0.1% concentration and tested for wetting power by the standard Draves test (AATCC Method 17-52) at 77° F. Other portions were tested for foaming by the Ross-Miles pour foam test described in Interscience Manual 4 (TP670-A1-F3) “Detergency Evaluation and Testing.” The results are shown in Table 1.

Table 1

Sample No.

Fatty Acid Used

Percent F.A.

Percent OT-75%

Wetting Time, Seconds

Initial Drain Foam, Time, Ml. Seconds

EXAMPLE 2

Another set of samples was therefore prepared in which diethylene glycol monostearate was added to “Aerosol OT-75%” along with free stearic acid, using the procedure described in Example 1. The compositions and test results at 0.1% concentration in water at 77° F. were as follows:

Table 2

Sample No.

Percent Stearic

Acid

Percent D.E.G. Stearate

Percent OT-75%

Wetting Time, Seconds

Initial Foam, Ml.

Drain Time, Seconds .______ None.—.........

Stearic__________ „do___________ do___________ do._________

Oleic____________ “Acintol FA-2.

.___________do___________

2.5

100 97.5 95 90 85 95 05 90

Inst.

1.0

1.5

1.7

2.7

1.5

1.5

1.7

325

275

235

200

125

230

238

210

300 140

These test results show that the higher fatty acids are effective to control the foaming of sodium dioctyl sulfosuccinate without substantially reducing its wetting power. However the samples were not stable and tended to become non-fluid on storage; and upon dilution with water there was considerable scum formation. It was found that these difficulties could be overcome by adding a diethylene glycol monoester of one or more of the higher fatty acids in amounts of about 25% to 200% based on the quantity of free fatty acid used.

2.

345.

6.

7_

8.

9.

2.5 5

2.5

50

93.5 92.5

1.2

1.7

2.7

3.6

4.6

5.4

9.2

1.5

1.7

275

225

200 125

100

225

275

142

28

300 32 140

These mixtures showed improved storage stability and iio fatty acid separation or scum formation was noted when they were diluted with water and tested.

The test results show that the diethylene glycol monostearate has little or no effect either on the wetting time of the sulfosuccinate or on the amount or stability of the foam. It functions, therefore, as a dispersing and fluidifying agent that prevents crystallization and separation of the stearic acid but does not interfere with its action as a foam inhibitor.

Larger batches having the following compositions were then prepared, the parts being by weight.

NO. 1

Parts “Aerosol OT-75%”90

Stearic acid, commercial 5

Diethylene glycol monostearate 5

NO. 2

Parts “Aerosol OT-75%” 89.4

Stearic acid, commercial 5

Diethylene glycol monostearate 5

Potassium stearate 0.6

NO. 3

Parts “Aerosol OT-75%” 80

Stearic acid, commercial_____ 10

Diethylene glycol monostearate 10

Potassium stearate 1

NO. 4 Parts “Aerosol OT-75%”85

Stearic acid, commercial 10

Diethylene glycol monostearate 5 no. 5 Parts “Aerosol OT-75%”85

Stearic acid, commercial 5

Diethylene glycol monostearate 10

Potassium stearate 1

NO. 6

Parts “Aerosol OT-75%”___________________________90 “Acintol FA-2” ______________________________ 5

Diethylene glycol monostearate of “Acintol FA-2” — 5 (“Acintol FA-2” is a redistilled grade of tall oil fatty acids containing 96.8% total fatty acids of which 50% is oleic γθ acid and 48 % is linoleic acid.)

These batches were stored in glass containers at room temperatures for several weeks. They were then found to be fluid and homogeneous. No fatty acid separation or scum formation was noted when they were dissolved in water to 0.1% solids.

2,869,382

EXAMPLE 3

Mixtures containing sodium di-n-octyl sulfosuccinate (A) and sodium di-(3,5-dimethylhexyl) sulfosuccinate (B) were prepared from 50% aqueous gels by the procedure described in Example 1 and tested. The compositions and results of the wetting and foam tests were as follows:

Table 3

4. A wetting composition consisting essentially of from 50 to 90 parts by weight of sodium di-(2-ethylhexyl) sulfosuccinate and from 10 to 50 parts by weight of a mixture of a fatty acid containing from 16 to 22 carbon atoms and a diethylene glycol monoester of a fatty acid containing from 16 to 22 carbon atoms, the weight ratio

<td rowspan="2"> Sample No.</td><td rowspan="2"> Percent Stearic Acid</td><td rowspan="2"> Percent D.E.G. Stearate</td><td rowspan="2"> Percent Wetting Agent (100% Basis)</td><td colspan="2"> Wetting Time, Sec.</td><td rowspan="2"> Initial Foam, Ml.</td><td rowspan="2"> Drain Time</td>

<td> 0.1%</td><td> 0.05%</td>

<td> 1.............</td><td> None</td><td> None</td><td> (A)</td><td> 8.5</td><td> 17.5</td><td> 300</td><td rowspan="3"> 250 ml. after 5 min. 200 ml. after 5 min. 225 ml. after 5</td>

<td> 2_____________</td><td> None</td><td> None</td><td> (B)</td><td> Inst.</td><td> 5.4</td><td> 250</td>

<td> 3.............</td><td> 5</td><td> 6</td><td> (A) 90</td><td> 7.5</td><td> 29</td><td> 250</td>

<td> 4.............</td><td> 5</td><td> 6</td><td> (B) 90</td><td> 2</td><td> 4.5</td><td> 240</td><td> min. 50 ml. after 5</td>

<td> δ.............</td><td> 7.6</td><td> 2.5</td><td> (A) 90</td><td> 7.5</td><td> 32</td><td> 200</td><td rowspan="4"> mln. 125 ml. after 5 min. 4 min. 4 ml. after 5 min. 100 ml. after 2 mln.</td>

<td> 6............</td><td> 7.6</td><td> 2.5</td><td> (B) 90</td><td> 2.5</td><td> 5.5</td><td> 225</td>

<td> 7.............</td><td> 10</td><td> 2.5</td><td> (A) 87.5</td><td> 11</td><td> 42</td><td> 160</td>

<td> 8.............</td><td> 10</td><td> 2.5</td><td> (B) 87.5</td><td> 3.5</td><td> 8</td><td> 200</td>

The test results show that the foam produced by these wetting agents is also reduced in the compositions of the invention although it is inherently much more stable than that of “Aerosol OT.” The samples showed no separation or solidification on storage and no scum was formed when they were diluted with water.