Silicone foam control compositions

Details Silicone foam control compositions Silicone foam control compositions

2000-06-30

2003-01-28

Metzmaier, Daniel S. (Department: 1712)

Colloid systems and wetting agents; subcombinations thereof; pro

Compositions containing an agent for breaking ; processes of...

Continuous liquid phase colloid system and discontinuous gas...

C516S117000, C524S588000

Reexamination Certificate

active

06512015

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to silicone foam control compositions. More particularly, this invention relates to silicone foam control compositions comprising a silicone antifoam agent, mineral oil, a polydiorganosiloxane containing at least one polyoxyalkylene group, and a finely divided filler.
BACKGROUND OF THE INVENTION
The use of various silicone containing compositions as antifoams or defoamers is known. In this regard, it is well established that this art is highly unpredictable and slight modification can greatly alter performance of such compositions. Most of these compositions contain silicone fluid (usually dimethylpolysiloxane), often in combination with small amounts of silica filler. Additionally, these compositions may include various surfactants and dispersing agents in order to impart improved foam control or stability properties to the compositions.
Silicone compositions which are useful as foam control agents have been taught in the art. For example, Aizawa et al., in U.S. Pat. Nos. 4,639,489 and 4,749,740, the disclosures of which are hereby incorporated by reference, teach a method for producing a silicone defoamer composition wherein a complex mixture of polyorganosiloxanes, filler, a resinous siloxane and a catalyst to promote reaction of the other components are heated together at 50° C. to 300° C.
More recently, a method for preparing a composition similar to that described by Aizawa et al., cited supra, was disclosed by Miura in U.S. Pat. No. 5,283,004, the disclosure of which is hereby incorporated by reference. In this disclosure, the above mentioned complex silicone mixture additionally contains at least 0.2 weight parts of an organic compound having at least one group selected from —COR, —COOR′ or —(OR″)
n
—, wherein R and R′ are hydrogen or a monovalent hydrocarbon group, R″ is a divalent hydrocarbon group having 2 to 6 carbon atoms and the average value of n is greater than one. It is further disclosed that all the ingredients, including a catalyst, must be reacted at elevated temperatures to obtain the desired antifoam agent.
John et al., in European Patent Application No. 217,501, published Apr. 8, 1987, discloses a foam control composition which gives improved performance in high foaming detergent compositions which comprises (A) a liquid siloxane having a viscosity at 25° C. of at least 7×10
−3
m
2
/s and which was obtained by mixing and heating a triorganosiloxane-endblocked polydiorganosiloxane, a polydiorganosiloxane having at least one terminal silanol group and an organosiloxane resin, comprising monovalent and tetravalent siloxy units and having at least one silanol group per molecule, and (B) a finely divided filler having its surface made hydrophobic. John et al. further describes a method for making the foam control compositions and detergent compositions containing said foam control compositions.
McGee et al. in U.S. Pat. No. 5,380,464 discloses a foam control composition comprising a silicone defoamer reaction product and a silicone glycol copolymer which is particularly effective in defoaming highly acidic or highly basic aqueous systems. However, when a foam control composition comprising a silicone antifoam agent and a silicone glycol copolymer is employed, it is added in the form of a liquid or after dilution with water to a foamable liquid thus requiring higher levels of the silicone copolymer.
McGee et al. in U.S. Pat. No. 5,543,082 discloses a foam control composition prepared by mixing at room temperature a silicone defoamer reaction product, a silicone glycol copolymer, and a hydroxyl-endblocked polydiorganosiloxane polymer.
In European Patent Application No. 0638346 is disclosed a composition comprising a reaction product, a nonaqueous liquid continuous phase, and a moderately hydrophobic particulate stabilizing aid. EP'346 discloses that the reaction product is prepared by heating a mixture of a polyorganosiloxane fluid, a silicon compound, a finely divided filler, and a catalytic amount of a compound for promoting the reaction of the other components at a temperature of 50° C. to 300° C. EP'346 further discloses that these compositions can further contain at least one nonionic silicone surfactant, and a nonreinforcing inorganic filler.
In European Patent Application No. 0663225 is disclosed a foam control composition comprising a silicone antifoam agent and a crosslinked organopolysiloxane polymer having at least one polyoxyalkylene group.
Fey et al. in U.S. Pat. No. 5,908,891 discloses a dispersible silicone composition comprising (I) a silicone composition prepared by reacting a polyorganosiloxane, a silicon compound, optionally a finely divided filler, and a catalytic amount of a compound for promoting the reaction of the other components and (II) mineral oil. Fey et al. further discloses that the mineral oil is effective as a dispersing agent for the silicone composition (I).
SUMMARY OF THE INVENTION
This invention relates to silicone foam control compositions. More particularly, this invention relates to silicone foam control compositions comprising a silicone antifoam agent, mineral oil, a polydiorganosiloxane containing at least one polyoxyalkylene group, and a finely divided filler.
It is an object of the present invention to prepare silicone compositions which can be advantageously utilized to control foam in foam producing systems.
It is a further object of the present invention to provide silicone compositions wherein there is provided improvement in the control of foaming behavior.
It is a further object of the present invention to provide silicone foam control compositions which are stable and easily dispersible.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a silicone foam control composition comprising (I) a silicone antifoam agent prepared by reacting at a temperature of 50° C. to 300° C. a mixture comprising: (i) 100 weight parts of at least one polyorganosiloxane selected from the group consisting of (A) a polyorganosiloxane having a viscosity of about 20 to 100,000 mm
2
/s at 25° C. and being expressed by the general formula R
1
a
SiO
(4-a)/2
in which R
1
is a monovalent hydrocarbon or halogenated hydrocarbon group having 1 to 10 carbon atoms and a has an average value of 1.9 to 2.2, (B) a polyorganosiloxane having a viscosity of 200 to about 100 million mm
2
/s at 25° C. expressed by the general formula R
2
b
(R
3
O)
c
SiO
(4-b-c)/2
in which R
2
is a monovalent hydrocarbon or halogenated hydrocarbon group having 1 to 10 carbon atoms, R
3
is hydrogen or a monovalent hydrocarbon group having 1 to 10 carbon atoms, b has an average value of 1.9 to 2.2 and c has a sufficiently large value to give at least one —OR
3
group in each molecule, at least one such —OR
3
group being present at the end of the molecular chain, and (C) a mixture of (A) and (B); (ii) 0.5 to 20 weight parts of at least one silicon compound selected from (a) an organosilicon compound of the general formula R
4
d
SiX
4-d
in which R
4
is a monovalent hydrocarbon group having 1 to 5 carbon atoms, X is selected from a halogen atom or a hydrolyzable group and d has an average value of one or less, (b) a partially hydrolyzed condensate of said compound (a), (c) a siloxane resin comprising (CH
3
)
3
SiO
1/2
units and SiO
4/2
units wherein the ratio of (CH
3
)
3
SiO
1/2
units to SiO
4/2
units is 0.4:1 to 1.2:1, or (d) a condensate of said compound (c) with said compound (a) or (b); and (iii) a catalytic amount of a compound for promoting the reaction of components (i) and (ii); (II) at least one mineral oil; (III) at least one polydiorganosiloxane having at least one polyoxyalkylene group; and (IV) at least one finely divided filler. The silicone foam control compositions of this invention can optionally comprise a polyglycol.
The silicone foam control compositions of this invention comprise (I) a silicone antifoam agent, (II) at least one mineral oil, (III) at least one polydiorganosiloxane containing at least one polyoxyalkylene group, and

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