Silicone foam control agent

Details Silicone foam control agent Silicone foam control agent

2000-08-11

2003-02-18

Metzmaier, Daniel S. (Department: 1712)

Cleaning compositions for solid surfaces, auxiliary compositions

Cleaning compositions or processes of preparing

Specific organic component

C516S118000, C516S120000, C516S121000, C510S347000, C510S349000, C510S361000, C510S377000, C510S507000

Reexamination Certificate

active

06521586

ABSTRACT:

FIELD OF THE INVENTION
This invention is concerned with silicone-based foam control agents, particularly for use in aqueous compositions, preferably detergent compositions.
In many aqueous systems which are used e.g. in food processes, textile dying, paper production, sewage treatment and cleaning applications, surface active agents are present either as an unwanted ingredient or as deliberately introduced materials to achieve a certain function. Due to the presence of these surface active agents foam is often generated. In certain applications, such as in dish washing by hand, this is a welcome effect but in other applications foam generation can lead to unsatisfactory results. This is for example the case in the dyeing of textiles or in the manufacture of paper. In other applications, for example the use of detergent compositions for domestic laundering, the production of foam needs to be controlled rather than avoided. It is important to keep foam formation to an acceptable level when laundering is performed in automatic washing machines, particularly front loading machines. Excessive foam would cause overflow of the washing liquor onto the floor as well as reduction in the efficiency of the laundering operation itself.
BACKGROUND OF THE INVENTION
Silicone-based foam control agents are known and have been incorporated into for example heavy duty detergent powders and liquids for use in automatic washing machines. Silicone foam control agents are regarded as very effective in this application as they can be added in very small quantities and are not affected by e.g. the hardness of water, while traditional foam control compositions, such as soaps, require a certain water hardness for their effectiveness.
The detergent industry is constantly going through an evolution where, due to environmental concern, energy conservation efforts, machine design changes, water conservation and changing laundering habits there is a move towards the use of detergent compositions which will perform at higher efficiency than hitherto. There is a need to control foam from e.g. increased surfactant levels in the detergent compositions, use of surfactants which have a higher foam profile than traditional surfactants, changing laundering conditions. Since silicone foam control agents do not directly contribute to the cleaning power of a detergent composition it is desirable to keep the addition level of such foam control agents to a minimum. There has therefore arisen a need to develop improved foam control agents for incorporation in detergent compositions.
Silicone foam control agents are mostly based on organopolysiloxane materials, which may be linear or branched, and which may contain a variety of silicon-bonded substituents. EP 217501 describes a foam control agent wherein a liquid siloxane component is obtained by mixing 100 parts by weight of a polydiorganosiloxane having triorganosiloxane end-groups, 10 to 125 parts of a polydiorganosiloxane having at least one terminal silanol group and at least 40 silicon atoms and 0.5 to 10 parts of an organopolysiloxane resin comprising monofunctional and tetrafunctional siloxane units in a ratio of from 0.5:1 to 1.2:1, and having at least one silanol group per molecule, and there-after heating the mixture. The specification describes the need to control the amount of resin used in order to retain a liquid polymer, avoiding a gel structure. This indicates that some branching occurs in the siloxane component of the foam control agent. Although foam control agents according to EP 217501 perform adequately in many applications, there is a continuing search for improved foam control agents.
JP-A-56-139107 describes a self-emulsifying antifoaming agent comprising an organopolysiloxane oxyalkylene copolymer of the formula
where G is an oxyalkylene group; Y is —CH2CHR″—R5—D or —CH2CHR″COOR″, where R″ is H or alkyl, R5 is divalent hydrocarbon, for example ethylene, propylene, butylene, phenylene or phenethylene, and D is H or OH; a, b and c are each 0, 1, 2 or 3 and a+b+c=3.
GB2257709 describes a foam control agent which is particularly useful when incorporated in detergent compositions where a high level of high foaming surfactants is present, and comprises a branched polydiorganosiloxane which is prepared through hydrosilylation.
BRIEF SUMMARY OF THE INVENTION
There is still a need to provide more efficient foam control agents. We have now found that if organopolysiloxane materials with certain aromatic substituents are used in the presence of certain organosilicon resins, a more efficient foam control is obtained.
According to a first aspect of the invention, there is provided a foam control agent, comprising (A) an organopolysiloxane material having at least one silicon-bonded substituent of the formula X—Ph, wherein X denotes a divalent aliphatic organic group bonded to silicon through a carbon atom and Ph denotes an aromatic group, (B) an organosilicon resin and (C) a hydrophobic filler. The aromatic group can be unsubstituted or substituted.
DETAILED DESCRIPTION OF THE INVENTION
The organopolysiloxane material (A) is preferably a fluid and is preferably a polydiorganosiloxane. The polydiorganosiloxane (A) preferably comprises diorganosiloxane units of the formula
where Y is an alkyl group having 1 to 4 carbon atoms, preferably methyl. These diorganosiloxane units containing a —X—Ph group may comprise substantially all or a majority of the diorganosiloxane units in organopolysiloxane (A), but preferably comprise up to 50 or 60%, most preferably 5 to 40%, of the diorganosiloxane units in (A). The group X is preferably a divalent alkylene group having from 2 to 10 carbon atoms, most preferably 2 to 4 carbon atoms, but can alternatively contain an ether linkage between two alkylene groups or between an alkylene group and —Ph, or can contain an ester linkage. Ph is preferably a moiety containing at least one aromatic ring —C
6
R
5
, wherein each R independently denotes hydrogen, halogen, hydroxyl, an alkoxy group having 1 to 6 carbon atoms or a monovalent hydrocarbon group having 1 to 12 carbon atoms, or wherein two or more R groups together represent a divalent hydrocarbon group. Ph is most preferably a phenyl group, but may be substituted for example by one or more methyl, methoxy, hydroxyl or chloro group, or two substituents R may together form a divalent alkylene group, or may together form an aromatic ring, resulting in conjunction with the Ph group in e.g. a naphthalene group. A particularly preferred X—Ph group is 2-phenylpropyl —CH
2
—CH(CH
3
)—C
6
H
5
. Alternatively Ph can be a heterocyclic group of aromatic character such as thiophene, pyridine or quinoxaline.
The polydiorganosiloxane (A) also preferably comprises at least 50% diorganosiloxane units of the formula
where Y′ is a hydrocarbon group having 1 to 24 carbon atoms, preferably an aliphatic group of up to 6 carbon atoms, for example ethyl, propyl, isobutyl, methyl, hexyl or vinyl, or lauryl or a cycloalkyl group such as cyclohexylethyl. Mixtures of alkyl groups Y′ can be used. It is believed that the enhanced foam control of the antifoam agents of the invention may involve interaction between the Ph groups of (A) and the organosilicon resin (B), and the Ph groups may be more accessible if no long chain alkyl groups are present. Other groups can be present as Y′, for example haloalkyl groups such as chloropropyl or acyloxyalkyl or alkoxyalkyl groups. At least some of the groups Y′ can be phenyl groups or substituted phenyl groups such as tolyl; aromatic groups bonded direct to silicon are not equivalent to the groups —X—Ph but can be present as Y′.
The organopolysiloxane material (A) may be made by any suitable method, but preferably is made by hydrosilylation reaction between a siloxane polymer having a number of silicon-bonded hydrogen atoms with the appropriate amount of X″—Ph molecules, wherein X″ is as described for X, but has aliphatic unsaturation in the terminal group, allowing addition reaction w

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