# US 4,396,524 A · Preparation of polysiloxane block polymers and their use as foam inhibitors

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- Number: US 4,396,524 A
- Document ID: US4396524A
- Status: Granted
- Kind: A
- Application number: 06/218,575
- Filed: 1980-12-22
- Granted: 1983-08-02
- Earliest claimed: 1979-12-24
- Assignees: Henkel Kommanditgesellschaft auf Aktien
- Inventors: Hans U. Hempel; Edmund Schmadel; Herbert Reuter; Gunther Vogt
- Web page: https://patentgrep.com/patent/US4396524A

## CPC

- C11D 3/373: {containing silicones}
- B01D 19/0409: {compounds containing Si-atoms}
- C08G 77/44: containing only polysiloxane sequences
- C08K 3/36: Silica
- C11D 3/0026: {Low foaming or foam regulating compositions}
- C11D: DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)

## Abstract

This invention is directed to a method of preparing block copolymers useful as foam inhibitors, which method comprises the steps of: (1) mixing (a) from 100 parts by weight of a polydimethylsiloxane that is liquid at 20.degree. C., and (b) from about 2 to 20 parts by weight of a spatially cross-linked polysiloxane resin with a molecular weight of from about 1000 to 10,000; (2) heating said mixture in the presence of a catalyst until the viscosity is at least 200 mPa.s, as measured at 20.degree. C., to form a block polymer; (3) mixing said block polymer with (c) from about 0.5 to 15 parts by weight of a silicon dioxide aerogel; and (4) heating the mixture from step (3).

## Claims

### Claim 1

A method for preparing a foam-inhibiting composition comprising the steps of:
(1) mixing (a) 100 parts by weight of polydimethylsiloxane that is liquid at 20.degree. C., and (b) from about 2 to 20 parts by weight of a spatially cross-linked polysiloxane resin with a molecular weight of from about 1000 to 10,000, which is comprised of structural elements of the general formula ##STR4## wherein R consists of from about 40 to 100 mol percent of a phenyl, phenylethyl, or alkyl radical having from 2 to 8 carbon atoms and of from 0 to about 40 mol percent of a methyl group, and X and Y, which can be the same or different, have the same meaning as R or can be OH, O.sub.1/2, methyl, or --OC.sub.n H.sub.2n-1, wherein n is a number of from 1 to 4, with the proviso that the content of OH groups is from about 0.1 to 10 percent by weight, based on the total weight of the polysiloxane resin, to form a mixture thereof;
(2) heating said mixture to temperatures of at least 80.degree. C. in the presence of a catalytically effective amount of a catalyst comprising an acid substance selected from the group consisting of Lewis acids and acid-activated bleaching earths or a basic substance selected from the group consisting of quaternary ammonium bases with alkyl groups and/or hydroxyalkyl groups having from 1 to 4 carbon atoms and alkali metal hydroxides, and optionally, an organic solvent that does not react with the reaction components, until the viscosity increases steadily after an induction period and has reached a value of at least 200 mPa.s, as measured at 20.degree. C., to form a block polymer;
(3) mixing said block polymer in a known manner with (c) from about 1 to 15 parts by weight of a silicic acid aerogel to form a mixture thereof; and
(4) heating said mixture from step (3).

### Claim 2 (depends on 1)

The method of claim 1, wherein the silicic acid aerogel (c) is silanated.

### Claim 3 (depends on 1)

The method of claim 1, wherein cyclic polydimethylsiloxanes that contain 3 or more siloxane groups and/or linear polydimethylsiloxanes with from about 10 to 100 siloxane groups are used as component (a).

### Claim 4 (depends on 1)

The method of claim 1, wherein phenylmethylpolsiloxane resins with a content of from about 1 to 6 percent by weight of hydroxyl groups and with a molar ratio of phenyl to methyl groups of from about 2:3 to 10:1 are used as component (b).

### Claim 5 (depends on 1)

The method of claim 1, wherein phenylethylpolysiloxane resins with a content of from about 0.5 to 10 percent by weight of hydroxyl groups are used as component (b).

### Claim 6 (depends on 1)

The method of claim 1, wherein alkylpolysiloxane resins with branched alkyl groups containing from about 3 to 8 carbon atoms and with a content of hydroxyl groups of from about 0.5 to 8 percent by weight are used as component (b).

### Claim 7 (depends on 1)

The method of claim 1, wherein phenylethylmethylpolysiloxanes or C.sub.3 -C.sub.8 -alkylmethylpolysiloxanes having branched C.sub.3 -C.sub.8 -alkyl radicals, either with a content of from about 1 to 6 percent by weight of hydroxyl groups and a molar ratio of phenylethyl or C.sub.3 -C.sub.8 -alkyl groups to methyl groups of from about 100:1 to 2:3 are used as component (b).

### Claim 8 (depends on 1)

The method of claim 1, wherein the polysiloxane resins (b) have a molecular weight of from about 1200 to 5000.

### Claim 9 (depends on 1)

The method of claim 1, wherein from about 3 to 20 parts by weight of component (b) are used per 100 parts by weight of component (a).

### Claim 10 (depends on 1)

The method of claim 1, wherein from about 1 to 5 parts by weight, based on 100 parts by weight of component (a), of acid-activated bleaching earth are used as catalyst, and the procedure is carried out in the absence of solvents.

### Claim 11 (depends on 1)

The method of claim 1, wherein the catalyst is a basic substance selected from the group consisting of quaternary ammonium bases with alkyl groups having from 1 to 4 carbon atoms and alkali metal hydroxides, and the procedure is carried out in the presence of a solvent selected from the group consisting of saturated, aliphatic, and aromatic hydrocarbons and carboxylic acid esters, said solvent having a boiling point above 100.degree. C.

### Claim 12 (depends on 1)

The method of claim 1, wherein component (b) comprises less than 10 parts by weight, per 100 parts of component (a), and less than 1.2 parts by volume of a solvent are used, based upon 1 part by weight of components (a) and (b).

### Claim 13 (depends on 12)

The method of claim 12, wherein less than 1 part by volume of solvent is used.

### Claim 14 (depends on 1)

The method of claim 1, wherein less than 10 parts by weight of component (b) are used and the mixture of components (a) and (b) is heated until the viscosity of the block polymer is at least 400 mPa.s.

### Claim 15 (depends on 14)

The method of claim 14, wherein the viscosity of the block polymer is at least 500 mPa.s.

### Claim 16 (depends on 1)

The method of claim 1, wherein 10 or more parts by weight of component (b) are used and the mixture of components (a) and (b) is heated until the viscosity of the block polymer is at least 300 mPa.s.

### Claim 17 (depends on 1)

The method of claim 1, wherein the mixture of components (a) and (b) is heated at a temperature of from about 100.degree. to 160.degree. C.

### Claim 18 (depends on 1)

The method of claim 1, wherein the mixture of components (a) and (b) is heated for from about 6 to 20 hours.

### Claim 19 (depends on 1)

A foam-inhibiting composition prepared according to claim 1.

### Claim 20 (depends on 19)

A method for inhibiting foam in washing, dishwashing, or cleaning agents which comprises incorporating therein a foam-inhibiting composition of claim 19.

### Claim 21 (depends on 1)

A block polymer prepared according to claim 1, steps (1) and (2).

### Claim 22 (depends on 1)

The method of claim 1, wherein from about 0.001 to 1 part by weight, based on 100 parts by weight of component (a), of Lewis acid is used as catalyst.

### Claim 23 (depends on 1)

The method of claim 1, wherein from about 0.001 to 1 part by weight, based on 100 parts by weight of component (a), of basic substance is used as catalyst.