PRIOR ART

The polypropylene glycols and polyoxyethylene-polyoxypropylene copolymers which have bee employed individually as antifoaming agents have several drawbacks. Primarily, they have limited water solubility and dispersibility so that large amounts of these antifoamers must be employed and, even then, the defoaming action is relatively low. Generally, a foam head of less than 2 cm on a 60 square cm surface area is the upper limit of tolerance for commercial defoaming applications and for certain uses not more than 0.3 cm is required. Secondly, formulations containing these compounds are somewhat viscous which presents pumping difficulties in antifoaming processing. Several solid non-foaming dispersing formulations have also been proposed as in U.S. 3,959,176; however these present problems of dispersibility and cannot be pumped into foamable solutions.

Accordingly, it is an object of this invention to overcome the above deficiencies of the prior art and to provide a particularly effective antifoaming/defoaming mixture which is economically prepared.

Another object of this invention is to provide a liquid mixture which is capable of defoaming an aqueous system at a greatly increased rate.

Another object is to provide a liquid antifoaming/defoaming composition having significantly reduced viscosity which can be most economically incorporated into a foamable liquid or added to a foam.

Still another object is to prepare a composition which, in addition to its antifoaming and defoaming properties, provides anti-swelling in solutions of various polymers.

These and other objects of the invention will become apparent from the following description and disclosure.

THE INVENTION

In accordance with this invention there is provided a liquid antifoaming/defoaming mixture or blend of components having a cloud point less than 35 and comprising:

(a) between about 10 and about 90% by weight of an alcohol alkoxylate having the formula

, 3 , 3

HO(CH ₂ CHO) _a (CH ₂ CH ₂ 0) _b (CH ₂ CHO) _C H ;

or

HO _z H

or a mixture thereof;

(bf between about 90 and about 10% by weight of polypropylene glycol having the formula

CH-, HO(CH ₂ -CHO) _d H

and

(c) between about 0.3 and about 10% by weight hydrophobic silica based on components (a) + (b) ,

wherein the lettered subscripts have the following values:

the sum of a + c = 10 to 150, preferably 20 to 70

b = 2 to 100, preferably 4 to 20

d = 15 to 200, preferably 25 to 100

the sum of + z = 2 to 40, preferably 4 to 15

y = 30 to 100, preferably 40 to 80

The cloud points of instant mixtures are below 35; although a cloud point of from about 1 to about 25 is most beneficial.

Component (a) of the present composition is a copolymer having a number average molecular weight of between about 675 and about 15,000, preferably between about 1,000 and about 10,000.

Preferred blends of the present composition are those wherein component (a) and component (b) are each present in an amount between about 35% and about 65% by weight; most preferred are those having about equal proportions of component (a) and component (b) and where propylene oxide units, with respect to ethylene oxide units, predominate in the overall composition. The hydrophobic silica is preferaby employed at concentrations between about 0.1 and about 8% by weight, most desirably, when a liquid mixture having a viscosity of not more than 500 cps is required, the concentration of the silica is not greater than 5% by weight. Although the viscosity of the liquid mixture can vary between about 100 and about 5,000 cps, depending upon its intended use, viscosities in the lower portion of this range, e.g. less than 500 cps, are

usually desired for processing purposes. While increased hydrophobic silica content materially raises the viscosity, such increased amounts do not provide any antifoaming benefit. Accordingly, the amount of hydrophobic silica above 10% by weight is not desirable.

The hydrophobic silica component of the composition, as known in the art, is prepared from hydrophilic silica which is treated to render the silica hydrophobic. One suitable method for rendering the silica hydrophobic is to permanently affix a liquid hydrophobic polysiloxane oil onto the silica particles. Since hydrophobic silica is well known in the art, no detailed description thereof is deemed necessary for a complete understanding of the present invention. The preparation of hydrophobic silica is described in U.S. Patent Nos. 3,207,698; 3,408,306; and 3,076,768, as well as the references referred to in such patents, all of which are hereby incorporated by reference. A preferred silica is a precipitated silica, such as the precipitated silica sold as Quso-G30 or Quso WR-83.

The above blend of components provides a hydrophobic/hydrophilic balance which allows faster diffusion of the antifoamer composition into the liquid/air interface and rapidly transports silica to the interface where a small amount efficiently performs defoaming action. The components of the above mixture also interact to effect destructurization of the monomolecular foamed layer by increasing the free energy of interaction between the foam forming molecules which leads to liberation of air and collapse of bubbles. Because of the hydrophobic/hydrophilic balance in the above formulation, the present composition has greater affinity for, and faster action in, aqueous systems which are subject to foaming. The present blend is capable of reducing the foam head of a foamed liquid by more than 70% upon contact and in less than 1.5 minutes completely destroying the foam.

In addition to its defoaming and antifoaming functions, the present composition provides anti-swelling properties to certain polymers including polyvinyl halides, polypropylenes, polyethylenes, polytetrafluoroethylenes, polychlorotrifluoroethylenes and the like.

Examples of foamed or foamable solutions to which the present composition is applied, include the alkali and alkaline earth metal salts, as well as ammonium salts, of alkyl benzene sulfonates and lauryl sulfates, lauryl ether sulfates, alkoxylated alkyl phenols, urethane polymers, phosphate ester surfactants, salts of fatty acids employed in the paper making industry and photopolymers, such as methacrylic alkyl esters and their carboxylic salts, employed for printed board circuits in the electronic industry. The present blends are useful as defoamers or antifoamers for laundry detergents, dishwashing formulations, paper making processes, metal working processes and many others.

To effect defoaming or antifoaming only a small amount of the blend is needed to provide the desired result. Generally between about 0.001% and about 3% by weight, preferably between about 0.05% and about 0.5% by weight of the present blend, based on foamed or foamable liquid, is employed to defoam on contact. The present mixture is economically and conveniently prepared by merely mixing components (a) , (b) and (σ) in any order at a temperature between about 10°C. and about 100°C. under atmospheric conditions for a period of up to 3 hours depending upon the volume. Generally, the formulation is prepared within a 1 hour mixing period at ambient temperature depending upon the volume and the mixing equipment employed. The resulting mixture is preferably used in undiluted condition; although in certain cases

where desired, it can be diluted to a desired concentration with an inert solvent such as water, PEG, PPG, benzene, heptane, hydrocarbons and the like before contact with a foamed layer or before admixture with a foamable liquid prior to agitation. The defoaming or antifoaming operations are carried out under the same conditions of temperature and pressure described above using conventional foam breaking or liquid mixing techniques.

Having generally described the invention, reference is now had to the accompanying examples which include preferred embodiments. These examples are not to be construed as limiting to the scope of the present antifoaming/defoaming and anti-swelling compositions which are more broadly set forth above and in the appended claims.

EXAMPLE 1

The following composition A was mixed for 5 minutes at ambient temperature under atmospheric conditions in a 200 ml glass beaker.

(a) 50 g. of 10% polyoxyethylene-90% polyoxypropylene copolymer having polyoxyethylene capping blocks (PEGOL L-121) and having a molecular weight of 4,440.

(b) 49 g. of polypropylene glycol having a molecular weight of 4,000 (ALKAPOL PPG 4000).

(c) 1 g. of hydrophobic silica (QUSO WR-83) .

The antifoaming property of the above composition was tested as follows. As a control, 200 g. of 0.1% anionic dodecyl benzene sulfonate sodium salt in water was stirred at ambient temperature in a glass measuring column for 1 minute at 1000 rpm and developed a foam head of 10 cm. Stirring was then discontinued and the liquid left to stand for 1 minute. The foam head was unchanged after 1 minute standing time. The above procedure was repeated except that 0.1% of the above liquid composition was added to the sulfonate before stirring. After stirring this mixture for 1 minute, only 1.5 cm of foam head developed and after l minute standing time, the sulfonate was completely defoa ed.

EXAMPLE 2

The antifoaming test of Example 1 was repeated except that a photopolymer, i.e. methacrylic acid methyl ester (RISTON in 0.85% Na C0 ₃ ) , was substituted for the foamable sulfonate salt. The results were as follows

cm Initial foam head of photopolymer in absence of Composition A/foam head after 1 minute 3.1/2.8

Initial foam head of photopolymer containing 0.1% of Composition A/foam head after 1 minute 0.1/0.0

EXAMPLE 3

Example 1 was repeated except that the following composition (B) was substituted for composition (A) .

(a) 50 g. of 10% polyoxyethylene-90% polyoxypropylene copolymer having the polyoxypropylene capping blocks (PEGOL 31R1) and having a molecular weight Of 3200.

(b) 49 g. of polypropylene glycol having molecular weight of 4000 (AL APOL PPG 4000) .

(c) 1 g. of hydrophobic silica (QUSO WR-83)

The results of the antifoaming tests were as follows.

cm Initial foam head developed in the absence of Composition B/foam head after 1 minute 10.0/10.0

Initial foam head developed in liquid incorporating 0.1% of Composition B/foam head after 1 minute 1.7/0.0

EXAMPLE 4

Example 1 was repeated except that the following composition (C) was substituted for composition (A) .

(a) 50 g. of 20% polyoxyethylene-80% polyoxypropylene copolymer having the polyoxypropylene capping blocks (PEGOL 25R2) and having a molecular weight of 3120.

(b) 49 g. of polypropylene glycol having molecular weight of 4000 (ALKAPOL PPG 4000) .

(c) 1 g. of hydrophobic silica (QUSO WR-83)

The results of the antifoaming tests were as follows.

cm Initial foam head developed in the absence of Composition C/foam head after 1 minute 10.0/10.0

Initial foam head developed in liquid incorporating 0.1% of Composition C/foam head after 1 minute 1.8/0.1

COMPARATIVE EXAMPLE 5

Example 1 was repeated except that the following composition (D) was substituted for composition (A) .

(a) 50 g. of 80% polyoxyethylene-20% polyoxypropylene copolymer having the polyoxypropylene capping blocks.

(b) 49 g. of polypropylene glycol having molecular weight of 2000 (ALKAPOL PPG 2000) .

(c) 1 g. of hydrophobic silica (QUSO WR-83) .

The results of the antifoaming tests were as follows.

cm Initial foam head developed in the absence of Composition D/foam head after 1 minute 10.0/10.0

Initial foam head developed in liquid incorporating 0.1% of Composition D/foam head after 1 minute 5.6/4.5

This example illustrates the affect of excess moles of polyoxyethylene in the overall composition.

COMPARATIVE EXAMPLE 6

Example 1 was repeated except that the following composition (E) was substituted for composition A.

(a) 50 g. of polyoxyethylene (21 moles) polyoxypropylene (16 moles) copolymer having polyoxyethylene capping block groups (PEGOL L-35) and having a molecular weight of 1900.

(b) 49 g. of polypropylene glycol having a molecular weight of 4000 (ALKAPOL PPG 4000) .

(c) 1 g. of hydrophobic silica (QUSO WR-83).

The results of the antifoaming tests were as follows.

cm Initial foam head developed in the absence of Composition E/foam head after 1 minute 10.0/10.

Initial foam head developed in liquid incorporating 0.1% of Composition E/foam head after 1 minute 5.2/4.5

This example illustrates the affect resulting fro component (a) where subscript y has a value less than 30. As shown, the foam head was not reduced to an acceptable limit.

COMPARATIVE EXAMPLE 7

Example 1 was repeated except that the following composition (F) was substituted for composition A-

(a) 45 g. of 10% polyoxyethylene-90% polyoxypropylene copolymer having polyoxyethylene capping blocks (PEGOL L-121) .

(b) 43 g. of polypropylene glycol having a molecular weight of 4000 (ALKAPOL PPG 4000) .

(c) 12 g. of hydrophobic silica (QUSO WR-83) .

Composition F has a viscosity of 4,000 cps which clogged in the supply pump. Accordingly, the 0.1% addition to the foamable liquid was achieved manually with vigorous mixing for a period of more than 4 hours at 110°C. The results of the antifoaming tests are as follows.

cm Initial foam head developed in the absence of Composition F/foam head after 1 minute 10/10

Initial foam head developed in liquid

+ 0.1% of Composition F/foam head after 1 minute 1.5/0.0

Although composition F achieved good antifoaming, the mixture was highly viscous and could not be pumped into the foamable liquid.