Colloid systems and wetting agents; subcombinations thereof; pro – Compositions containing an agent for breaking ; processes of... – Continuous liquid phase colloid system and discontinuous gas...
Reexamination Certificate
1999-09-15
2001-01-23
Lovering, Richard D. (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, C516S118000, C516S119000, C516S123000
Reexamination Certificate
active
06177481
ABSTRACT:
The present invention relates to mixtures comprising at least one polysiloxane defoamer, at least one emulsifier, at least one nonionic surfactant, at least one polyurethane thickener and water, to a process for the production thereof and to the use thereof.
Defoamer emulsions are macroemulsions in which the average particle size of the dispersed particles may very well exceed 10 &mgr;m or even 100 &mgr;m. The disperse phase consists of the defoamer active substance alone or contains this in a carrier medium, such as, for example, an organic solvent.
It is known to use organopolysiloxanes as defoamer active substances. The term organopolysiloxanes may denote, on the one hand, pure silicone oils (polydimethylsiloxanes) but, on the other, may also include polysiloxane/polyoxyalkylene block copolymers. The oils may contain finely divided solids, which generally further promote the defoaming action. Examples of such finely divided solids are highly disperse, optionally hydrophobised silicas obtained by pyrolysis or precipitation, magnesium or aluminium oxide as well as magnesium stearate.
As a consequence of the relatively large particles in the disperse phase, defoamer emulsions have a tendency to settle and coalesce. It is thus necessary to stabilise the emulsions by adding suitable auxiliary substances (for example protective colloids). This increases the viscosity of the continuous phase, thereby counteracting settling. The protective colloids may also congregate at the disperse phase interface, thereby sterically stabilising it and preventing coalescence.
A list of compounds which may be used as protective colloids is given, for example, in the publication by W. B. Shapiro, “Thickening Oil-in-Water Emulsions” in Cosmetics & Toiletries 97 (1982), pp. 27 et seq.
Examples of such protective colloids are cellulose derivatives, such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose or hydroxymethylpropylcellulose, as well as synthetic polymers, such as for example polyvinyl alcohol or polyacrylates together with biosynthetic polymers, such as for example xanthan gum.
It is known to use certain linear water-soluble or water-dispersible polyurethanes, such as for example
as protective colloids for defoamer emulsions (see e.g. DE-A 42 37 754).
The defoamer emulsions described therein are, however, neither sufficiently stable in storage nor sufficiently effective.
An object of the present invention was thus to provide a mixture which was highly effective with regard to defoaming and also very stable in storage.
It has surprisingly now been found that these characteristics may be improved if associative thickeners, i.e. thickeners comprising molecules having hydrophilic and (purposefully incorporated) hydrophobic groups, based on polyurethane are used in combination with certain nonionic surfactants.
The present invention accordingly provides mixtures comprising
at least one polysiloxane defoamer A),
at least one emulsifier B),
at least one nonionic surfactant C) of the formula R—(AO)
x
OH wherein
R is an optionally substituted C
6
-C
14
aromatic residue,
AO is C
2
-C
4
alkylene oxide and
x is 1 to 300,
at least one polyurethane thickener having a weight average of 5000 to 60000 D) and
water E).
In the following the term substituted has the meaning of C
1
-C
12
-alkyl groups.
The polysiloxane defoamer A) comprises any type of defoamer active substances based on polysiloxane, as are for example described in U.S. Pat. No. 5,082,590, U.S. Pat. No. 3,984,347 as well as the polyether siloxanes described in DE-A 4 343 185 or U.S. Pat. No. 5,153,258. Preferably, however, A) is a silicone oil, such as for example polydimethylsiloxane and/or organically modified siloxanes, such as for example polysiloxan polyether copolymers, optionally in combination with at least one solid. This solid is preferably a hydrophobic solid. The solid may be hydrophobised in advance or in situ using familiar methods or may already be hydrophobic.
The solid is preferably silica, magnesium or aluminium oxide or magnesium stearate, particularly preferably silica.
Both nonionic as well as anionic and cationic emulsifiers may be used as the emulsifier B). Examples of nonionic emulsifiers are alkyl polyglycol ethers, preferably alkyl polyglycol ethers having 2 to 100 ethylene oxide units and alkyl residues with 8 to 20 carbon atoms, alkylaryl polyglycol ethers, preferably alkylaryl polyglycol ethers having 2 to 100 ethylene oxide units and 8 to 20 carbon atoms in the alkyl and aryl residues, ethylene oxide/propylene oxide block copolymers, preferably those having 8 to 100 ethylene oxide units, fatty acid polyglycol esters, preferably C
6
-C
24
fatty acid polyglycol esters containing 2 to 100 ethylene oxide units, such as for example polyoxyethylene triglycerides, natural substances and derivatives thereof, such as for example lecithin, lanolin, saponin, cellulose, cellulose alkyl ethers and carboxyalkylcellulose, the alkyl groups of which each have up to 4 carbon atoms, as well as linear organopolysiloxanes containing polar groups, in particular those having alkoxy groups with up to 24 carbon atoms and/or up to 40 ethylene oxide and/or propylene oxide groups.
Examples of anionic emulsifiers are alkyl sulphates, in particular those having a chain length of 8 to 18 carbon atoms, alkyl and alkyl ether sulphates having 8 to 18 carbon atoms in the hydrophobic residue and 1 to 40 ethylene oxide or propylene oxide units, sulphonates, preferably C
8
-C
18
alkyl sulphonates, C
8
-C
18
alkylaryl sulphonates, taurides, esters and semi-esters of sulphosuccinic acid with monohydric alcohols or alkylphenols having 4 to 15 carbon atoms, wherein these alcohols or alkylphenols may also be ethoxylated with 1 to 40 ethylene oxide units, alkyl and ammonium salts of carboxylic acids having 8 to 20 carbon atoms in the alkyl, aryl, alkaryl or aralkyl residue, as well as phosphoric acid partial esters and the alkali metal and ammonium salts thereof, preferably alkyl and alkaryl phosphates having 8 to 20 carbon atoms in the organic residue, alkyl ether or alkaryl ether phosphates having 8 to 20 carbon atoms in the alkyl or alkaryl residue with 1 to 40 ethylene oxide units.
Examples of cationic emulsifiers are salts of primary, secondary and tertiary fatty amines having 8 to 24 carbon atoms with acetic acid, sulphuric acid, hydrochloric acid and phosphoric acid, quaternary alkyl and alkylbenzene ammonium salts, preferably those with an alkyl group having 6 to 24 carbon atoms, particularly preferably halides, sulphates, phosphates and acetates, alkylpyridinium, alkylimidazolinium and alkyloxazolinium salts, preferably those with an alkyl chain having 1-18, preferably 6-18, especially the halides, sulphates, phosphates and acetates.
In a preferred embodiment of the present invention, the emulsifier is at least one nonionic emulsifier, particularly preferably polyoxyethylene triglycerides and/or polyethoxylated longer-chain alcohols, very particularly preferably polyoxyethylene triglycerides and polyethoxylated longer-chain alcohols “as used herein the term longer chain means from about 12 carbon atoms to about 24 carbon atoms”.
For the purposes of the invention, component C) is preferably at least one compound of the formula
R—[T—(Q′)
w
—H]
y
(I),
in which
R is a linear or branched hydrocarbon residue, preferably an aliphatic, aromatic, araliphatic or alkylaromatic hydrocarbon residue having 6 to 50 carbon atoms, and/or an aromatic or alkylaromatic C
6
-C
40
hydrocarbon residue comprising two or more aromatic rings and/or containing inert substituents, such as for example alkyl residues with 1 to 12 carbon atoms,
T is oxygen or a residue of the formula
Q′ denotes alkylene oxide units, preferably having C
2
-C
4
carbon atoms, particularly preferably ethylene oxide and/or propylene oxide units, providing that at least 70 mol. % of these units are ethylene oxide units,
z is a number from 1 to 300, preferably from 2 to 200 and particularly preferably from 5 to 100,
y is
Grape Wolfgang
Kaesler Karl-Heinz
Krott J{umlaut over (u)}rgen
Mazanek Jan
Bayer Aktiengesellschaft
Lovering Richard D.
Metzmaier Daniel S.
Norris McLaughlin & Marcus P.A.
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