Antifoam compositions - Patent Review 4584125

What is claimed is:

1. A foam destabilizing composition comprising (A) a foam destabilizing agent consisting essentially of

(1) a diorganopolysiloxane having terminal groups selected from the class consisting of hydroxyl, hydrocarbonoxy and triorganosiloxy groups and having the average formula ##STR13## (2) an amine containing compound selected from the group consisting of an aminofunctional organopolysiloxane having a viscosity of from 5 to 100,000 mPa.s at 25.degree. C., an organic amine of the formula ##STR14## and mixtures thereof, where R is a monovalent hydrocarbon radical having from 1 to 50 carbon atoms, in which an average of at least one R group of the diorganopolysiloxane has from 6 to 50 carbon atoms and the remaining R groups have from 1 to 5 carbon atoms, in which the ratio of R groups radical having from 1 to 5 carbon atoms to R groups having from 6 to 50 carbon atoms range from 1:2.5 to 5600:1, R.sup.1 is a monovalent hydrocarbon radical having from 1 to 25 carbon atoms, R.sup.2 is a divalent hydrocarbon radical having from 1 to 10 carbon atoms per molecule, with the proviso that at least one of the radicals represented by R.sup.1 or R.sup.2 must have at least 6 carbon atoms, a has an average value of from about 1.8 to 2.2, b is 0, 1 or 2, c is 0 or 1, and m has an average value greater than 3, in which the diorganopolysiloxane (1) is present in the destabilizing agent in an amount of from 4 to 96 percent by weight and the amine containing compound (2) is present in the destabilizing agent in an amount of from 96 to 4 percent by weight based on the weight of the destabilizing agent; (B) a nonaqueous dispersing agent; and (C) an inorganic filler.

2. The foam destabilizing composition of claim 1, wherein the composition contains water.

3. The foam destabilizing composition of claim 1, wherein the destabilizing agent is present in an amount of from 0.75 to 40 percent by weight based on the weight of the destabilizing composition.

4. The foam destabilizing composition of claim 1, wherein the nonaqueous dispersing agent (B) is present in an amount of from 1 to 98.75 percent by weight based on the weight of the destabilizing composition.

5. The foam destabilizing composition of claim 1, wherein the inorganic filler is present in an amount of from 0.5 to 60 percent by weight based on the weight of the destabilizing composition.

6. The foam destabilizing composition of claim 2, wherein the water is present in an amount up to 18 percent by weight based on the weight of the destabilizing composition.

7. The foam destabilizing composition of claim 1, wherein the amine compound is an aminofunctional organopolysiloxane.

8. The foam destabilizing composition of claim 1, wherein the amine compound is an organic amine of the formula ##STR15## where R.sup.1 is a monovalent hydrocarbon radical having from 1 to 25 carbon atoms, R.sup.2 is a divalent hydrocarbon radical having from 1 to 10 carbon atoms per molecule, with the proviso that one of the radicals represented by R.sup.1 or R.sup.2 must have at least 6 carbon atoms, b is 0, 1 or 2 and c is 0 or 1.

9. The foam destabilizing composition of claim 2, wherein the composition contains an emulsifying agent.

10. The foam destabilizing composition of claim 1, wherein the filler has a surface area of from about 150 m.sup.2 /g to 350 m.sup.2 /g.

11. The foam destabilizing composition of claim 1, wherein the nonaqueous dispersing agent (B) is a diorganopolysiloxane fluid having a viscosity of from about 10 to 5000 mPa.s at 25.degree. C.

12. The foam destabilizing composition of claim 1, wherein the nonaqueous dispersing agent (B) is a mineral oil having a viscosity of from 10 to 200 mPa.s at 25.degree. C.

13. The foam destabilizing composition of claim 1, wherein the nonaqueous dispersing agent (B) is a carboxylic acid ester having from about 14 to 24 carbon atoms.

14. The foam destabilizing composition of claim 1, wherein the nonaqueous dispersing agent (B) is a monohydric alcohol having from 8 to 18 carbon atoms.

15. A foam destabilizing composition comprising (A) from 0.75 to 40 percent by weight based on the weight of the destabilizing composition of a foam destabilizing agent consisting essentially of

(1) a diorganopolysiloxane having terminal groups selected from the class consisting of hydroxyl, hydrocarbonoxy and triorganosiloxy groups and having the average formula ##STR16## (2) an amine containing compound selected from the group consisting of an aminofunctional organopolysiloxane, an organic amine of the formula ##STR17## and mixtures thereof, where R is a monovalent hydrocarbon radical having from 1 to 50 carbon atoms, in which an average of at least one R group of the diorganopolysiloxane has from 6 to 50 carbon atoms and the remaining R groups have from 1 to 5 carbon atoms, in which the ratio of R groups having from 1 to 5 carbon atoms to R groups having from 6 to 50 carbon atoms range from 1:2.5 to 5600:1, R.sup.1 is a monovalent hydrocarbon radical having from 1 to 25 carbon atoms, R.sup.2 is a divalent hydrocarbon radical having from 1 to 10 carbon atoms per molecule, with the proviso that one of the radicals represented by R.sup.1 or R.sup.2 must have at least 6 carbon atoms, a has an average value of from about 1.8 to 2.2, b is 0, 1 or 2, c is 0 or 1, and m has an average value greater than 3, in which the diorganopolysiloxane (1) is present in the destabilizing agent in an amount of from 4 to 96 percent by weight and the amine containing compound (2) is present in the destabilizing agent in an amount of from 96 to 4 percent by weight based on the weight of the destabilizing agent; (B) a nonaqueous dispersing agent in an amount of from 1 to 98.75 percent by weight based on the weight of the destabilizing composition; and (C) an inorganic filler in an amount of from 0.5 to 60 percent by weight based on the weight of the destabilizing composition.

16. A process for preparing a foam destabilizing agent composition which comprises mixing a foam destabilizing agent consisting essentially of from 4 to 96 percent by weight based on the weight of the destabilizing agent of

(1) a diorganopolysiloxane having terminal groups selected from the class consisting of hydroxyl, hydrocarbonoxy and triorganosiloxy groups and having the average formula ##STR18## and from 96 to 4 percent by weight based on the weight of the destabilizing agent of

(2) an amine containing compound selected from the group consisting of an aminofunctional organopolysiloxane, an organic amine of the formula ##STR19## and mixtures thereof, where R is a monovalent hydrocarbon radical having from 1 to 50 carbon atoms, in which an average of at least one R group of the diorganopolysiloxane has from 6 to 50 carbon atoms and the remaining R groups have from 1 to 5 carbon atoms in which the ratio of R groups having from 1 to 5 carbon atoms to R groups having from 6 to 50 carbon atoms range from 1:2.5 to 5600:1, R.sup.1 is a monovalent hydrocarbon radical having from 1 to 25 carbon atoms, R.sup.2 is a divalent hydrocarbon radical having from 1 to 10 carbon atoms per molecule, with the proviso that one of the radicals represented by R.sup.1 or R.sup.2 must have at least 6 carbon atoms, a has an average value of from about 1.8 to 2.2, b is 0, 1 or 2, c is 0 or 1, and m has an average value greater than 3 with (B) a nonaqueous dispersing agent and thereafter adding (C) a filler to the resultant mixture.

Description Submit all comments and votes

The present invention relates to antifoam compositions and more particularly to antifoam compositions which will prevent or abate foaming in aqueous and nonaqueous systems.

BACKGROUND OF THE INVENTION

Antifoam compositions containing linear diorganopolysiloxanes such as dimethylpolysiloxanes have been widely used as defoamers in, for example, jet dyeing of textile materials.

Aqueous silicone emulsions containing dimethyl silicone fluids have been described, for example, in U.S. Pat. No. 4,194,988 to Schneider et al for defrothing purposes in which the dimethylpolysiloxanes are mixed with an emulsifier containing mono- or diesters of orthophosphoric acid until a clear solution is obtained and then an organic base or alkali is added to neutralize the clear solution.

Antifoam compositions for aqueous systems have been described in U.S. Pat. No. 3,666,681 to Keil, which contain (A) a water insoluble organic liquid such as a mineral oil, esters of carboxylic acids, monohydric alcohols, vegetable oils, polyoxypropylene and polyoxybutylene glycols; (B) an organopolysiloxane compound selected from a hydroxyl endblocked dimethylpolysiloxane fluid or a benzene soluble organopolysiloxane resin; (C) a silica filler; and (D) a compound selected from a hydrocarbon amine, ammonia or a disilazane.

An emulsion defoamer composition is also described in U.S. Pat. No. 4,225,456 to Schmidt et al which contains (A) hydrophobic silica; (B) an amide; (C) an organic polymer; (D) an emulsifier; (E) an oil, such as a mineral oil; (F) a silicone oil; and (G) water.

In contrast to the antifoam compositions described heretofore, the antifoam compositions of this invention have certain advantages. For example, emulsions of these antifoam compositions are more effective in an alkali medium and their effectiveness lasts for a longer period of time. Also, emulsions of this invention have a longer shelf-life, have better thermal stability and are more stable to mechanical stresses such as shear stresses. Moreover, the antifoam compositions of this invention are more effective in controlling foam formation in, for example, the evaporation of alkaline black liquor in the paper industry, textile dyeing, sewage disposal and in the concentration of synthetic rubber latices.

Therefore, it is an object of the present invention to provide a novel antifoaming composition which prevents or abates undesirable foaming in aqueous and nonaqueous systems. Another object of the present invention is to provide an antifoam composition having a longer shelf-life and better thermal stability. Still another object of the present invention is to provide an antifoam composition which is easily emulsified to form an aqueous or nonaqueous emulsion. A further object of the present invention is to provide an antifoam composition which is more effective in controlling foam formation.

SUMMARY OF THE INVENTION

The foregoing objects and others which will become apparent from the following description are accomplished in accordance with this invention, generally speaking, by providing foam destabilizing compositions for aqueous and nonaqueous systems comprising (A) a foam destabilizing agent containing (1) a diorganopolysiloxane having the average formula ##STR3## and (2) an amine containing compound selected from the group consisting of an aminofunctional organopolysiloxane and/or an organic amine having the formula ##STR4## where R is a monovalent hydrocarbon radical having from 1 to 50 carbon atoms, in which an average of at least one R group contains from 6 to 50 carbon atoms, R.sup.1 is a monovalent hydrocarbon radical having from 1 to 25 carbon atoms, R.sup.2 is a divalent hydrocarbon radical having from 1 to 10 carbon atoms, with the proviso that at least one of the radicals is represented by R.sup.1 or R.sup.2 must have at least 6 carbons, a has an average value of from about 1.8 to 2.2, b is 0, 1 or 2, c is 0 or 1, and m has a value greater than 3; (B) a nonaqueous dispersing agent; (C) an inorganic filler; and (D) water, if desired.

DESCRIPTION OF THE INVENTION

The foam destabilizing composition of this invention comprises

(A) from 0.75 to 40 weight percent of a foam destabilizing agent based on the weight of the foam destabilizing composition, in which the foam destabilizing agent contains (1) a diorganopolysiloxane in an amount of from 4 to 96 weight percent based on the weight of the foam destabilizing agent and (2) an amine compound selected from the group consisting of an organic amine and/or an aminofunctional organopolysiloxane; in an amount of from 96 to 4 weight percent based on the weight of the destabilizing agent;

(B) from 1 to 98.75 weight percent based on the weight of the composition of a nonaqueous dispersing agent;

(C) from 0.5 to 60 weight percent of an inorganic filler; and

(D) from 0 to 18 weight percent of water based on the weight of the foam destabilizing composition.

The diorganopolysiloxane employed in the foam destabilizing agent may be represented by the general formula ##STR5## where R is a monovalent hydrocarbon radical having from 1 to 50 carbon atoms, in which at least one R group contains from 6 to 50 carbon atoms, and the remaining R groups have from 1 to 5 carbon atoms, a has an average value of from about 1.8 to 2.2 and m has an average value greater than 3.

It is preferred that the ratio of R groups having from 1 to 5 carbon atoms to R groups having from 6 to 50 carbon atoms range from 1:2.5 to 5600:1, preferably from 10:1 to 5000:1, and more preferably from 10:1 to 100:1.

The diorganopolysiloxanes may be either linear or branched siloxanes having an average of from about 1.8 to 2.2 organic radicals per silicon atom. The diorganopolysiloxanes may be fluids or gums having a viscosity of from 5 to 1,000,000 mPa.s at 25.degree. C. and more preferably from 100 to 500,000 mPa.s at 25.degree. C. Also, it is possible to blend high and low viscosity fluids to form a fluid having the desired viscosity range.

Examples of suitable monovalent hydrocarbon radicals represented by R are alkyl radicals such as ethyl, propyl, isopropyl, butyl, isobutyl, isopentyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, docosyl, tetracosyl, hexacosyl, octacosyl, triacontyl, dotriacontyl, tetracontyl and pentacontyl radicals; alkenyl radicals such as vinyl, allyl, 2-butenyl, 2-pentenyl, and cyclohexenyl radicals; aryl radicals such as the phenyl and naphthyl radicals; alkaryl radicals such as the tolyl, xylyl, cumenyl, mesityl, ethylphenyl, methyl- .alpha.-naphthyl and 1-ethyl-B-naphthyl radicals; and aralkyl radicals, such as the benzyl, alpha-phenyl-ethyl,alpha-phenyl-propyl, alpha-phenyl-isopropyl, alpha-phenyl-butyl, alpha-phenyl-isobutyl and beta-phenyl-sec-butyl radicals.

Examples of linear diorganopolysiloxanes which may be used are those that are terminated with R.sub.3 'SiO.sub.0.5 units, in which R' is the same as R above or a hydroxyl group or a hydrocarbonoxy radical. Specific examples of preferred diorganopolysiloxanes which may be employed are triorganosiloxy terminated diorganopolysiloxanes such as trimethylsiloxy terminated methylhexylpolysiloxanes, methyloctylpolysiloxanes, methyldecylpolysiloxanes, methyloctadecylpolysiloxanes, methylphenylpolysiloxanes, methyltriacontylpolysiloxanes, methyltetracontylpolysiloxanes and copolymers of said diorganopolysiloxanes and organosiloxanes in which the organic groups have from 1 to 4 carbon atoms. Also, hydroxyl, alkoxy or aryloxy terminated diorganopolysiloxanes may be employed.

The organic amine which may be employed in the foam destabilizing agent may be represented by the general formula ##STR6## where the R.sup.1, which may be the same or different, is a saturated or unsaturated monovalent hydrocarbon radical having from 1 to 25 carbon atoms, R.sup.2 is a divalent hydrocarbon radical having from 1 to 10 carbon atoms, with the proviso that at least one of the radicals represented by R.sup.1 or R.sup.2 must have at least 6 carbon atoms, b is 0, 1 or 2 and c is 0 or 1.

Examples of monovalent hydrocarbon radicals represented by R.sup.1 are alkyl radicals such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, dodecyl and octadecyl radicals; alkenyl radicals, such as vinyl, allyl, 1-butenyl, 2-butenyl, 1-isobutenyl, 2-pentenyl, 1-hexenyl, 2-hexenyl, octenyl, and decenyl radicals; aryl radicals, such as the phenyl radical; alkaryl radicals, such as tolyl, xylyl, o-cumenyl, m-cumenyl, p-cumenyl and the ethylphenyl radical and aralkyl radicals, such as benzyl, phenyl-ethyl, phenyl-propyl and the phenyl-butyl radicals.

Examples of saturated and unsaturated divalent hydrocarbon radicals represented by R.sup.2 are alkylene radicals such as ethylene, trimethylene, tetramethylene, hexamethylene, octamethylene and decamethylene radicals; alkenylene radicals such as propenylene, butenylene, hexenylene, octenylene and decenylene radicals and aryl radicals such as the phenylene radical.

Suitable examples of organic amines are aniline, m-toluidine, 2,3-xylidine, N-ethyl-N-methyl-hexylamine, N,N-dimethyl-hexylamine, N-hexyl-allylamine, N-hexylamine, dipropylamine, N,N-dimethyl-phenylamine, N-phenyl-benzylamine, N-cyclohexylhexylamine, benzylamine, phenethylamine, 1-naphthalenemethylamine, and diamines, such as ##STR7##

Aminofunctional polysiloxanes which may be employed in the foam stabilizing agent have at least one unit of the general formula ##STR8## where R.sup.3, which may be the same or different, is a divalent hydrocarbon radical selected from the group consisting of saturated divalent hydrocarbon radicals having from 2 to 10 carbon atoms, a divalent hydrocarbonoxy radical in which the oxygen is in the form of an ether linkage and an unsaturated divalent hydrocarbon radical having from 2 to 10 carbon atoms, R.sup.4 is a monovalent hydrocarbon radical having from 1 to 18 carbon atoms, a and b are the same as above.

Examples of suitable divalent hydrocarbon radicals represented by R.sup.3 are alkylene radicals having from 2 to 10 carbon atoms such as ethylene, trimethylene, tetramethylene, hexamethylene and octamethylene radicals. The divalent hydrocarbonoxy radicals may be represented by the general formula, (--OC.sub.2 H.sub.4 --).sub.d, (--OC.sub.2 H.sub.4 OCH.sub.2 --).sub.d and (--OCH.sub.3 H.sub.6 --).sub.d in which d is a number of from 1 to 30, such as ethylene oxide, trimethylene oxide and polymers thereof. Examples of suitable unsaturated divalent hydrocarbon radicals are alkenylene radicals such as vinylene, propenylene, butenylene, hexenylene, octenylene and decenylene radicals.

The aminofunctional siloxanes may be prepared by equilibrating a mixture containing an organopolysiloxane and an aminofunctional silane or siloxane in the presence of an equilibration catalyst. Organopolysiloxanes which may be used in the preparation of these aminofunctional siloxanes are cyclic siloxanes having the general formula ##STR9## or linear or branched organopolysiloxanes having the general formula

R.sub.Y.sup.4 SiR.sub.z.sup.4 O.sub.4-Y-z/2

in which R.sup.4 represents monovalent hydrocarbon radicals having from 1 to 18 carbon atoms, y is a number of from about 0.5 to 3.0, z is a number of from 0.001 to 1 and the sum of y and z is a number of from 1 to 3 and w is a number of from 3 to 10.

Examples of suitable cyclic organopolysiloxanes which may be used in the formation of these aminofunctional silicone fluids are hexamethylcyclotrisiloxane, hexaphenylcyclotrisiloxane, 1,2,3-trimethyl-1,2,3-triphenylcyclotrisiloxane, 1,2,3-trimethyl-1,2,3-trivinylcyclotrisiloxane, octamethylcyclotetrasiloxane, 1,2,3,4-tetramethyl-1,2,3,4-tetravinylcyclotetrasiloxane and the like. Cyclic siloxanes in which w has a value from 3 to 4 are preferred.

Examples of linear or branched chained siloxanes which may be used are triorganosiloxy end-blocked organopolysiloxanes such as trimethylsiloxy end-blocked dimethylpolysiloxanes, diethylpolysiloxanes, methylphenylpolysiloxanes, diphenylpolysiloxanes and copolymers thereof.

Examples of suitable aminofunctional silanes are beta-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, methyl-beta-(aminoethyl) gamma-aminopropyldimethoxysilane, omega-aminohexyltributoxysilane, beta-(aminoethoxy)hexyltriethoxysilane, beta-(aminopropoxy)butyltributoxysilane, methyl-beta-(aminopropoxy)propyldi-(aminoethoxy)silane, and silanes of the formula ##STR10##

Representative examples of aminofunctional siloxanes are ##STR11##

The aminofunctional siloxanes and methods for preparing the same are described in U.S. Pat. No. 3,890,269 to Martin, which is incorporated herein by reference.

Other aminofunctional siloxanes which may be used are those obtained from the reaction of polyaminoalkyl alkoxysilanes of the formula

R.sub.f.sup.4 (E.sub.h M)Si(OR.sup.4).sub.3-f

or the corresponding siloxanes with organosiloxanes of the general formula

R.sub.x.sup.4 Si(OH).sub.n O.sub.4-n-x/2

where R.sup.4 is the same as above, M is an aliphatic hydrocarbon radical having from 1 to 10 carbon atoms and having a valence of h+1, where h is a number of from 1 to 3, E is a monovalent radical attached to M by a carbon-nitrogen bond and is composed of carbon, nitrogen and hydrogen atoms and contains at least one amine group, f is a number of from 0 to 2, n has a positive average value up to and including 2, and x is a number of from about 0.5 to 2.49 and the sum of n and x has an average value up to and including 3.

These aminofunctional siloxane copolymers may be prepared by contacting the aminofunctional silanes or the corresponding siloxanes with the organosiloxane in a liquid phase in accordance with the procedure described in U.S. Pat. No. 3,355,424 to Brown, which is incorporated herein by reference.

Other aminofunctional siloxanes which may be used are tertiary aminoorganosilanes or siloxanes which have at least one ether linkage in the organic group connecting the tertiary amino group to the silicon atoms.

These tertiary aminoorganosiloxanes may be prepared by a platinum catalyzed addition reaction of an alkenyl ether of a tertiary hydroxyalkyl amine and a hydrosilicon compound (i.e., a silane or siloxane containing silicon-bonded hydrogen) in accordance with the procedure described in U.S. Pat. No. 3,402,191 to Morehouse.

Other aminofunctional siloxanes which may be used are those derived from the condensation and/or the partial hydrolysis and condensation of a liquid silanol chain-stopped polydiorganosiloxane and an aminoalkoxyalkylsilane or an aminoalkoxyalkenylsilane having the formula ##STR12## and, if desired, aminoalkylsilanes or from the condensation of the above liquid silanol chain-stopped polydiorganosiloxane with the above aminofunctional silanes in various mole ratios. In the above formula R" is a monovalent hydrocarbon radical having from 1 to 18 carbon atoms or hydrogen; R.sup.3 and R.sup.4 are the same as above and g is a number of from 1 to 10. These aminofunctional siloxanes may be prepared in accordance with the procedure described in U.S. Pat. No. 3,544,498 to Holdstock et al in which a mixture containing the silanol chain-terminated polyorganosiloxane and the aminoalkoxyalkylsilane or aminoalkyoxyalkenylsilane and, if desired, the aminoalkylsilane are partially hydrolyzed and condensed. Also, the aminofunctional organopolysiloxanes may be prepared in accordance with the procedure described in U.S. Pat. No. 3,355,424 to Brown in which an aminofunctional silane and silanol chain-stopped polyorganosiloxanes are condensed.

The viscosity of the aminofunctional siloxanes may range from about 5 up to about 100,000 mPa.s at 25.degree. C., preferably from about 50 to 50,000 mPa.s and more preferably from about 100 to 20,000 mPa.s at 25.degree. C.

The foam destabilizing agent, which consists of a mixture of a diorganopolysiloxane and an amine compound is present in the foam destabilizing composition in an amount of from 0.75 to 40 percent by weight, preferably from 2 to 35 percent by weight and more preferably from 5 to 30 percent by weight based on the weight of the foam destabilizing composition.

The diorganopolysiloxane is present in the foam destabilizing agent in an amount of from 4 to 96 percent, preferably from 15 to 75 percent by weight based on the weight of the foam destabilizing agent.

The amine compound is present in the foam destabilizing agent in an amount of from 96 to 4 percent, preferably from 90 to 10 percent based on the weight of the foam destabilizing agent.

Any nonaqueous liquid which does not substantially interfere with the effectiveness of the foam destabilizing agent may be employed in the compositions of this invention. Nonaqueous liquids such as a liquid petrolatum, vegetable oils, diorganopolysiloxane fluids, carboxylic acid esters having from about 14 to about 24 carbon atoms and monohydric alcohols having from 8 to 18 carbon atoms and mixtures thereof may be employed in the compositions as dispersing agents.

It is preferred that the liquid petrolatum (mineral oil) have a viscosity of from about 10 to 200 mPa.s at 25.degree. C.

Vegetable oils which are employed in the compositions as dispersing agents are generally derived from the seeds of plants and generally are mixtures of mixed glycerides. Preferably, the vegetable oils have a viscosity of from about 10 to 200 mPa.s at 25.degree. C.

Diorganopolysiloxane fluids which may be employed as nonaqueous dispersing agents in the antifoam compositions are trialkylsiloxy endblocked diorganopolysiloxanes having a viscosity of from about 10 to 5000 mPa.s at 25.degree. C. and more preferably from about 100 to 4000 mPa.s at 25.degree. C. Examples of suitable diorganopolysiloxanes are trimethylsiloxy endblocked dimethylpolysiloxanes, triethylsiloxy endblocked diethylpolysiloxanes, and copolymers having dimethylsiloxane units and diphenylsiloxane units or methylphenyl and dimethylsiloxane units. Preferably, the organopolysiloxanes are trimethylsiloxy endblocked polydimethylsiloxanes. These organopolysiloxane fluids are well-known in the art and generally consist predominantely of diorganosiloxane units (R.sub.2.sup.4 SiO).

Preferably, the carboxylic acid esters employed in the compositions of this invention have from 14 to 24 carbon atoms and more preferably from 16 to 20 carbon atoms. Suitable examples of carboxylic acid esters which may be used are isobutyl stearate, isobutyl palmitate, butyl oleate, isocetyl stearate and butoxethyl stearate.

Examples of monohydric alcohols which may be employed are octyl alcohol, 1-decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and tallow alcohol.

The amount of nonaqueous dispersing agent present in the foam destabilizing composition may range from 1 to 99 percent by weight, preferably from 2 to 90 percent by weight and more preferably from 5 to 80 percent by weight based on the weight of the foam destabilizing composition.

The fillers used in the antifoams of this invention may be any fillers which have been or could have been used heretofore in the preparation of antifoams containing an organopolysiloxane and a filler. Examples of such fillers are titanium oxide, calcium carbonate, aluminum oxide, ground quartz, talc, magnesium oxide, zinc oxide and finely divided silicas which have a particle size that does not exceed 25 microns.

The preferred silicas are pyrogenically prepared or precipitated silicon dioxide having a surface area of from about 150 m.sup.2 /g up to about 350 m.sup.2 /g. Additional examples of fillers which may be used in this invention are lithium stearate and magnesium aluminum silicate. Other fillers which may be used are products which remain solid at least at the temperature at which the antifoam is to be used and which are obtained from the reaction of at least one monovalent or polyvalent isocyanate with at least one organic compound containing at least one hydrogen atom which can react with the isocyanate group, such as the reaction product of naphthylene diisocyanate and cyclohexylamine. It is preferred that fillers prepared from the isocyanate and the organic compound be prepared in the presence of an organopolysiloxane containing dihydrocarbon siloxane units. Mixtures of various fillers as well as treated fillers may be employed in the antifoams of this invention.

The amount of inorganic filler may range from about 0.5 to 60 percent by weight, preferably from 1 to 50 percent by weight and more preferably from 5 to 40 percent by weight based on the weight of the foam destabilizing composition.

The defoamer compositions of this invention need not contain water in order to be an effective antifoam. Oftentimes, it is preferred that the composition be free of water. However, when water is present, it generally ranges from about 0 to 18 percent by weight, preferably from 2 to 15 percent by weight and more preferably from 5 to 12 percent by weight based on the weight of the foam destabilizer composition.

When the foam destabilizing compositions of this invention are emulsified with water, it is preferred that an emulsifying agent be employed. Water-soluble emulsifiers are well-known. Nonionic emulsifiers are preferred, especially those which are liquid at room temperature or melt on moderate heating under the conditions of the process of this invention. Mixtures of such emulsifiers may also be used. Examples of nonionic emulsifiers which may be used are ethoxylated fatty alcohols, ethoxylated fatty acids, ethoxylated fatty esters of polyols, such as, glycerol, sorbitol, or sorbitan, ethoxylated alkyl phenols, polyethers containing ethylene oxide and propylene oxide groups and water-soluble silicon polyethers. Watersoluble polyoxyalkylene-polysiloxane block copolymers are especially suitable. Furthermore, ethoxylated amines, amides, or amidoamines may be used. Ionic, water-soluble surfactants can also be used. Of the anionic surfactants, the sulfates and sulfonates of organic compounds must be especially mentioned. As cationic compounds, quaternary ammonium compounds with longchain alkyl residues, as well as betaines, are suitable.

The amount of emulsifying agent present in the destabilizing compositions may range from about 2 to 30 percent, preferably from 3 to 25 percent and more preferably from about 5 to 20 percent by weight, based on the weight of the destabilizing agent.

The foam destabilizing compositions of this invention may be prepared in any conventional manner. Although the addition of the ingredients is not critical, it is preferred that the foam destabilizing agent be mixed with the nonaqueous dispersing agent, followed by the addition of the inorganic filler. When water is added to the composition, it is preferred that the water and emulsifying agent be added prior to the addition of the inorganic filler. The ingredients can be handmixed or they can be mixed in any suitable mechanical mixer, such as a leaf or disk stirrer, or a planetary mixer. The antifoam composition can be prepared at room temperature and at atmospheric pressure. However, if desired, higher or lower temperatures as well as higher or lower pressures may be used. However, temperatures in excess of about 100.degree. C. should be avoided.

Preferably, the destabilizing compositions are prepared at elevated temperatures, such as from 25.degree. to about 100.degree. C. and more preferably from about 30.degree. to about 80.degree. C.

Other ingredients which may be added to the foam destabilizing compositions of this inve