Defoamer and/or deaerator based on oil-in-water dispersions

Details Defoamer and/or deaerator based on oil-in-water dispersions Defoamer and/or deaerator based on oil-in-water dispersions

2001-02-08

2003-11-18

Harlan, Robert (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S287000, C526S317100, C526S318000, C526S319000, C526S347100

Reexamination Certificate

active

06649721

ABSTRACT:

The present invention relates to antifoams and/or deaerators based on oil-in-water dispersions, which contain, in the hydrophobic oil phase, at least one compound effective as an antifoam and/or deaerator and, if required, further components.
EP-A-0 149 812 discloses antifoams which are based on oil-in-water emulsions and contain from 0.05 to 5% by weight of a high molecular weight, water-soluble homo- or copolymer of acrylic acid, methacrylic acid, acrylamide or methacrylamide as stabilizer. The oil phase of the emulsions contains, for example as an antifoam compound, a C
12
-C
26
-alcohol or a distillation residue which is obtained in the preparation of alcohols having a relatively high number of carbon atoms by oxo synthesis or by the Ziegler process and which may furthermore be alkoxylated. Further antifoam substances are, for example, fatty esters of C
12
-C
22
-carboxylic acids with a monohydric to trihydric C
1
- to C
18
-alcohol and/or hydrocarbons having a boiling point of above 200° C. or fatty acids of 12 to 22 carbon atoms. The mean particle diameter of the oil phase of the oil-in-water emulsions is from 0.5 to 15 &mgr;m.
DE-A-30 01 387 discloses aqueous emulsifier-containing oil-in-water emulsions which contain relatively high-melting aliphatic alcohols and contain hydrocarbons which are liquid at room temperature. The oil phase of the oil-in-water emulsions can, if required, also contain further components acting as antifoams, for example relatively high-melting nonaromatic hydrocarbons, fatty acids or derivatives thereof, for example fatty esters, beeswax, carnauba wax, Japan wax and montan wax.
EP-A-0 531 713 discloses antifoams which are based on oil-in-water emulsions and whose oil phase contains an alcohol of at least 12 carbon atoms, fatty esters of alcohols of at least 22 carbon atoms and C
1
- to C
36
-carboxylic acids, or fatty esters of C
12
- to C
22
-carboxylic acids with monohyric to trihydric C
1
- to C
18
-alcohols or a hydrocarbon having a boiling point of above 200° C. or fatty acids of 12 to 22 carbon atoms in combination with polyglyceryl esters, which are obtainable by at least 20% esterification of polyglycerol mixtures with at least one fatty acid of 12 to 36 carbon atoms. These oil-in-water emulsions, too, are stabilized with the aid of a water-soluble emulsifier.
EP-A-0 662 172 discloses antifoams which are based on water-in-oil emulsions and are used as antifoams, for example in paper mills and are still sufficiently effective even at relatively high temperatures of the water circulation. Such antifoams contain, in the oil phase,
(a) fatty esters of C
12
- to C
22
-carboxylic acids with monohydric to trihydric C
1
- to C
22
-alcohols,
(b) polyglyceryl esters which are obtainable by at least 20% esterification of polyglycerols which have at least 2 glycerol units with at least one C
12
- to C
36
-fatty acid and
(c) fatty esters of C
12
- to C
22
-carboxylic acids and polyalkylene glycols, the molar mass of the polyalkylene glycols being up to 5000 g/mol. The hydrophobic phase can, if required, contain further components, such as alcohols of at least 12 carbon atoms or hydrocarbons having a boiling point above 200° C. These oil-in-water emulsions are likewise stabilized with the aid of an emulsifier.
EP-A-0 696 224 discloses aqueous antifoam dispersions whose dispersed phase contains fatty alcohols having melting points above 40° C. and ketones having melting points above 45° C. and, if required, natural or synthetic waxes having melting points above 50° C.
EP-A-0 732 134 discloses antifoams and/or deaerators based on oil-in-water emulsions for aqueous media which tend to form foam, the oil phase of the emulsions containing
(a) at least one alcohol of at least 12 carbon atoms, a distillation residue which is obtainable in the preparation of alcohols having a relatively high number of carbon atoms by oxo synthesis or by the Ziegler process, or a mixture of said compounds and
(b) at least one ester of a sugar alcohol having at least 4 OH groups or at least 2 OH groups and at least one intramolecular ether bond and a fatty acid of at least 20 carbon atoms in a molar ratio of 1 to at least 1, where the free OH groups of these esters may be completely or partly esterified with C
12
- to C
18
-carboxylic acids.
The hydrophobic phase can, if required, contain further antifoam compounds, such as fatty esters of alcohols of at least 22 carbon atoms and C
1
- to C
36
-carboxylic acids, polyethylene waxes, natural waxes, hydrocarbons having a boiling point of above 200° C. or fatty acid of 12 to 22 carbon atoms.
From 0.1 to 5% by weight of an emulsifier are required for stabilizing the oil-in-water emulsions. The known oil-in-water emulsions have the disadvantage that they separate into a fat phase and a water phase on prolonged storage. Some of the known oil-in-water emulsions even become solid and are therefore unusable for the intended application.
It is an object of the present invention to provide antifoams and/or deaerators based on oil-in-water emulsions where the emulsions are free from high molecular weight polymers having a thickening effect and have a sufficient shelf life.
We have found that this object is achieved, according to the invention, by antifoams and/or deaerators based on oil-in-water emulsions which contain, in the hydrophobic oil phase, at least one compound effective as antifoam and/or deaerator and, if required, further components, if the oil-in-water emulsions contain from 0.01 to 3% by weight of a water-soluble, amphiphilic copolymer having acid groups or of a water-soluble salt thereof as a stabilizer.
Compounds acting as antifoams and/or deaerators are, for example, naturally occurring or synthetically prepared alcohols having at least 12 carbon atoms in the molecule. Examples of such alcohols are myristyl alcohol, cetyl alcohol, stearyl alcohol, palmityl alcohol, tallow fatty alcohol and behenyl alcohol, and synthetically prepared alcohols, such as saturated, straight-chain alcohols obtainable, for example, by the Ziegler process by oxidation of aluminum alkyls. Synthetic alcohols are also obtained by oxo synthesis. These are as a rule alcohol mixtures. The alcohols may contain, for example, up to 48 carbon atoms in the molecule. Very effective antifoams contain, for example, mixtures of at least one C
12
- to C
26
-alcohol and at least one fatty alcohol having 28 to 48 carbon atoms in the molecule, cf. EP-A-0 322 830. Instead of the pure alcohols, distillation residues which are obtainable in the preparation of alcohols having a relatively high number of carbon atoms by oxo synthesis or by the Ziegler process may also be used as antifoam compounds. Further compounds which are suitable as antifoams and/or deaerators are alkoxylated alcohols and alkoxylated distillation residues which are obtained in the preparation of alcohols by oxo synthesis or by the Ziegler process. The alkoxylated compounds are obtainable by reacting the long-chain alcohols or distillation residues with ethylene oxide or with propylene oxide or a mixture of ethylene oxide and propylene oxide. Here, first ethylene oxide and then propylene oxide can be subjected to an addition reaction with the alcohols or the distillation residues, or propylene oxide and then ethylene oxide are subjected to said addition reaction. In general, up to 5 mol of ethylene oxide or propylene oxide are subjected to the addition reaction per OH group of the alcohol. Particularly preferred from the group consisting of the alkoxylated compounds are those reaction products which are prepared by an addition reaction of 1 or 2 mol of ethylene oxide with 1 mol of fatty alcohol or distillation residue.
The abovementioned fatty alcohols having at least 12 carbon atoms in the molecule are generally used together with other compounds likewise acting as antifoams. Such compounds are, for example, fatty esters of C
12
- to C
22
-carboxylic acids with monohydric to trihydric C
1
-C
18
-alcohols. Fatty acids on which these esters are based, are, for example, lauric acid, myristic acid, p

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