US2390212A - Antifoaming agents - Google Patents

Description

Patented Dec, 4, 1945 AGENTS James H. Fritz, Montclair, N. 1., assignor to Na.-

tional Oil Products Company,

Harrison, N. 1.,

a corporation of New J erscy No Drawing. Application September 22, 194% Serlal N0. 459,302

4 Claims. (Cl. 106-131) a ing fatty esters of glycols and polyglycols.

A large class of 'aqueous stocks such as solutions, suspensions, pulps, slurries and the like, tend to develop foam on the surface thereof under various conditions of use and processing. v Such foaming is highly disadvantageous in that it frequently causes loss of the aqueous stock due to the overflowing of the foam; interferes with the proper operation. of the apparatus containing the stock; brings about a flotation and aggregation of impurities of the stock; and results in irregularity of the materials treated with the stock or manufactured therefrom. On this account a large number of substances have been tried out for the prevention of foam on the surface of aqueous stocks, with varying success. These substances are variously termed, foam killers, "defoamers, "anti-irothing agents, "anti-foaming agents and the like. Not all agents which have been tried for this purpose are of general application, being ineffective or even harmful in the treatment of particular aqueous stocks. Furthermore, a large number of these agents are quite expensive and are not always available. Accordingly there exists a considerable field for the introduction of novel anti-foaming agents.

One object of this invention is to provide an anti-foaming agent for aqueous stocks which will be highly eflective when usedin minute amounts.

Another object is to provide an anti-foaming agent which may be made from cheaply and readily available materials.

Still another object is to provide an anti-foaming agent which will be compatible with a large variety of aqueous stock solutions.

These and other objects are secured in accordance with this invention by the addition, to

aqueous stocks which are foaming or likely to foam, of fatty esters of the glycols and polyglycols. These esters are preferably added in small amounts, and in the form of an aqueous emulsion, to the stock at any point in the processing or use of the stock at which foaming is apt to occur, or at some stage in advance of this point. The emulsion may advantageously include certain oily and waxy materials of high titre, which waxy substances considerably enhance and extend the action of the fatty esters. Such compositions, when added in even very small quantities, will abate foam that has already developed or will prevent the development of foam under conditions which would otherwise produce the same.

Referring to the glycols and polyglycols forming the alcoholic portion of the fatty esters employed in this invention, these may be any of the lower molecular weight alkylene glycols such as ethylene glycol, propylene glycol or butylen glycol. or the polymers of these glycols containing up to about 15 alkylene oxide residues. The unpolymerized glycols suitable for use in this invention are readily and cheaply obtained by the oxidation and hydration of unsaturated lower petroleum fractions and the polymerized glycols are readily and cheaply derived from the monomeric glycols by various well known condensation reactions, such as by heating the glycols or alkylene oxides under pressure for a sufllcient length of time to secure the desired condensation. Obviously the glycols and poly alkylene glycol rnishing the'alcoholic portion of the esters employed in this invention need not be pure substances, but may occur as heterogeneous mixtures of substances coming within "the above requirements.

The fatty residues combined in the esters employed in this invention may be in general those fatty residues whose hydrophilic derivatives exhibit appreciable surface activity, that is to say, those fatty residues containing upwards of 8, and preferably from 18 to 22, carbon atoms such as the capryl, lauryl, myristyl, stearyl, ricinoleyl, and the like residues. Preferably these residues will contain a hydroxyl Or other similar hydrophilic group, as the esters produced from such hydroxylated fatty residues exhibit a highly superior defoaming action. It is understood, of coufse, that instead of the pure fatty radicals, the esters employed in this invention may contain any mixture of fatty radicals meeting the requirements above outlined, such as the mixtures of fatty radicals occurring naturally in the various fats, oils and waxes of commerce, for instance in tallow lard, coconut 011, corn oil, cottonseed oil, linseed oil, olive oil, palm oil, peanut oil, soyabean oil menhaden oil, sperm oil and the like, and in the hydroxylated oils such as castor oil or oils in which hydroxyl radicals have been artificially developed. as by wet blowing or sulfonation and hydrolysis.

Referring to the nature and preparation of the glycol and polyglycoi fatty esters for use in this invention, these may be prepared by condensing the (poly) glycols and any 'suitable substances containing the fatty radicals in any appropriate manner. In all cases it is preferable that the proportions of the reactants and the conditions of condensation be such that at least one hydrorwl radical will be left free upon the glycol 01' poly glycol residue in order to impart to the ester a suitable degree of water-solubility or dispersibility. In the case of the glycols themselves and their lower polymers up to those containing about 5 or 6 ethylene oxide residues, such a free hydroxyl residue is absolutely necessary in order to secure the requisite degree of water solubility; and even in the higher polyglycols it is advantageous to leave such a free hydroxyl group, although the plurality of, polar ether linkages in such compounds will impart a sufilcient degree of water dispersibility without the presence of free hydroxyl groups. Thus it may be stated that the mathematical criterion of the operability of a given ester in the practice of this invention is that the sum of the number of free hydroxyl radicles, plus one-seventh of the number of alkylene oxide residues in the alcohol residue as combined in the ester, shall equal at least 1. The esteriflcation may be brought about by any suitable means which will not simultaneously bring about a deterioration of the glycol or polyglycol. One very excellent method for effecting this reaction is by the transesteriflcation of a fatty glyceride with the selected glycol or polyglycol in the presence of an alkaline catalyst. In such cases, in addition to the esters of the glycol or polyglycol, there will also be formed partial fatty glycerides, which will themselves contribute to the defoaming action of the composition as a whole.

As stated above, the compositions of this invention are preferably added in the form of readyprepared aqueous emulsions to the stocks to be defoamed. In commercial practice, the emulsions will ordinarily be prepared in a central establishment and distributed to the various users thereof, and accordingly it will be advantageous to include the least possible amount of water in emulsions intended for such distribution. In general, sta- -ble-emulsions according to this invention may be prepared containing as little as 30% water. These emulsions may, if necessary, be stabilized by the addition of small amounts of alkali, soap or other like emulsifiers. However, these extraneous emulsiflers detract from the foam-killing power of the emulsions, and their use should be kept to a minimum.

The emulsified compositions of this invention may contain, in addition to the fatty esters, certain hydrophobic greasy or waxy constituents of high titre, such as paraflin wax; the true waxes such as carnauba, candelilla and montan wax; stearic acid; and insoluble metallic soaps. Such constituents serve to extend, and partly replace. the fatty esters, and will accordingly hereinafter be designated hydrophobic extenders." The proportion of extenders may be varied as indicated by experience in various applications: in general, from about 1 to about parts of-the hydrophobic extenders may be employed for each part of ester, Certain of these extenders, particularly the hard vegetable waxes such as candelilla wax, appear to impart a certain metastability to the emulsions, so that the objectionable use of extraneous emulsifiers may be greatly reduced and even eliminated.

A large variety of aqueous stocks may be effectively defoamed in accordance with this insteps in the production of evaporated and condensed milk, etc.

The amount of the defoaming compositions of this invention required to prevent or destroy foam will vary in accordance with the nature of the material bein treated and with the circumstances which tend to produce the foaming thereof. Accordingly, no exact rule may be given on this point, and' the required amount in each case is best determined by preliminary trial and e periment.

Defoaming agents prepared as above described are effective in extremely small amounts. Further, these defoaming compositions are compatible with, and efiective in, a wide variety of aqueous stocks, not being affected by salts or acids. With the above general discussion in mind there are given herewith specific examples of the practice of this invention. All parts given are by weight.

Exmu I A number of batches of defoaming agents were prepared from various (poly) alkylene glycol fatty esters as follows: 15 parts of the selected ester, 20 parts of paraffin wait, '7 parts of stearic acid and 2 parts of candelilla wax were melted and stirred together to form a homogeneous melt. 2.6 parts of 49% aqueous potash were then stirred in, after which 53.4 parts of hot water were mixed in with vigorous agitation. The resulting emulsions, which were stable under the usual condi tions of storage and shipment, were then individually tested for defoaming power in glue solutions and on paper-stock, in the manner which will now be described.

Glue test 20 grams of glue were dissolved in 120 grams of water by heating to C. and .3 cc. of the defoamer under test were added thereto. cc. of the resulting solution were placed in a 250 cc. beaker, and agitated with a malted-milk mixer. The height of foam in the beaker was observed (1) 30 seconds, (2) 2 minutes and (3) 4 minutes after commencement of the agitation.

Paper stock test 2 parts of the defoamer under test were added to 97 /2 parts of water and the resultant solution was dripped into a stock of chip furnish ahead of the flat screens on a paper-board machine at the rate of 1 pint of the diluted solution per ton of air dry Paper stock.

The results of these tests are tabulated herevention and include, by way of example, glue with:

Height of foam in glue Ester used test (mm') Performance on paper machine Fatty radicals Glycol radicals V 30 sec. 2 min. 4 min.

Hydrogenated soyabean oil- Ethylene glycol 6 5 3 Good.

0 Propylene glycol... l5 6 5 Do. Hydrogenated castor oil. Ethylene glycol 10 7 Excellent.

Do Propylene glycol l0 6 3 Very good.

Mixed polymers of ethylene 3 0 0 Excellent; superior to all glycol averaging 9 ethylene others tried. glycol residues per molecule.

Exmu: II

Parts methylene glycol monostearate 25 Candelilla wax 4 Potash (50% aqueous) 2 Water 69 Mixed polyglycol stearate 1 25 Paraflln wax 25 Water 50 Mixed polyglycol stearate 1 16.7 Paraflin wax 33.3 W Water 50.0

Mixed polyglycol stearate 1 15 Paraffln wax 20 Hydrogenated soyabean oil 5 Potash (48% aqueous lye) 2 Water nu 58 100 Mixed polyglycol stearate 1 12.5 Paraflin wax 21.0 Hydrogenated sardine oil 7.5 Water 59.0

This ester was prepared from hydrogenated soyabean oil and mixed polymers of ethylene glycol averaging about 9 ethylene oxide residues per molecule.

Emulsions were prepared from the materials listed in each of the foregoing recipesaccording to the procedure outlined in connection with Example 1. Excellent foam-killing agents were secured in each case.

From the foregoing examples. it will be seen that this invention provides novel defoaming agents which are highly effective even when used in very minute quantities. Moreover, the fatty oils and the glycol and polyglycol esters serving as the chief ingredients thereof are cheaply and readily procurable from established and reliable sources of supply.

I therefore claim:

1. An anti-foaming agent comprising an aqueous emulsion of an ester of a fatty acid containing from 8-22 carbon atoms per molecule with a mixture of ethylene glycol polymers containing an average of 9 ethylene oxide residues per molecule of polymer, said emulsion also containing a hydrophobic extender selected from the class consisting of wax, stearic acid and insoluble metallic soaps.

2. An antifoaming agent comprising an aqueous emulsion of an ester of the fatty acid residues of hydrogenated castor oil with mixed polymers of ethylene glycol containing an average of 9 ethylene oxide residues per molecule of polymer, said emulsion also containing a hydrophobic extender selected from the class consisting of wax, stearlc acid and insoluble metallic soaps.

3. A substantially nonfoaming aqueous glue stock having dispersed therein an ester of a fatty acid containing from 8 to 22 carbon atoms per molecule with a mixture of ethylene glycol polymers containing an average of 9 ethylene oxide residues per molecule of polymer and a hydrophobic extender selected from the class consisting of wax, stearic acid and insoluble metallic soaps.

4. A substantially non-foaming paper pulp suspension having dispersed therein an ester of a fatty acid containing from 8 to 22 carbon atoms per molecule in a mixture of ethylene glycol polymers of 9 ethylene oxide residues per molecule of polymer and a hydrophobic extender selected from the class consisting of wax, stearic acid and insoluble metallic soaps.

JAMES H. FRITZ.