# US 11,028,228 B2 · Process for producing sperhical polysilsesquioxane particles

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- Number: US 11,028,228 B2
- Document ID: US11028228B2
- Status: Granted
- Kind: B2
- Application number: 16/484,331
- Filed: 2017-02-14
- Published: 2020-01-30
- Granted: 2021-06-08
- Earliest claimed: 2017-02-14
- Assignees: Wacker Chemie AG
- Applicants: Wacker Chemie AG
- Inventors: Sebastian Knoer; Kathrin Seilinger
- Web page: https://patentgrep.com/patent/US11028228B2

## CPC

- C08G 77/08: characterised by the catalysts used
- C08G 77/045: {containing less than 25 silicon atoms}
- C08J 3/14: by precipitation from solutions {(C08J3/122 takes precedence)}
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)

## Abstract

Spherical organopolysiloxane resin particles with improved flow properties can be reproducibly obtained employing trialkoxysilanes having different hydrolysable chlorine contents by regulating pH in a first, acid hydrolysis step, and then adjusting pH in a second step to a desired value between 1 and 6. Particles are allowed to grow without agitation in a subsequent basic condensation step.

## Claims

### Claim 1

A process for improving batch to batch reproducibility in a process for producing spherical polysilsesquioxane particles, where a trialkoxysilane raw material contains differing amounts of chlorine compounds in different batches, the process comprising: in a first step, reacting trialkoxysilane T which contains trialkoxysilanes of formula (I)
RSi(OR1)3 (I),
in which
R represents a hydrocarbon radical having 1 to 16 carbon atoms whose carbon chain may be interrupted by nonadjacent groups —O—,
R1 represents a C1- to C4-alkyl radical,
and which contains chlorine compounds,
by mixing the trialkoxysilane T with acidified water having a pH of at most 6 to afford a hydrolyzate,
in a second step the hydrolyzate is mixed with a solution of a base in water or C1-C4 alkanol,
and in a third step the mixture is stored for at least 2 h before isolating polysilsesquioxane particles,
wherein following the first step, the pH of a hydrolysate produced in the first step is measured and compared with a selected value, and if different from the selected value, the pH of the hydrolysate is adjusted to reduce the difference between the pH of the hydrolysate and the selected value.

### Claim 2 (depends on 1)

The process of claim 1, wherein each R independently represents an ethyl radical or a methyl radical.

### Claim 3 (depends on 1)

The process of claim 1, wherein each R1 independently represents an ethyl radical or methyl radical.

### Claim 4 (depends on 1)

The process of claim 1, wherein in the first step, the reaction to afford the hydrolyzate is carried out at a pH of 4.5 to 2.

### Claim 5 (depends on 1)

The process of claim 1, wherein the temperature of the reaction in the first step is 0° C. to 60° C.

### Claim 6 (depends on 1)

The process of claim 1, wherein in the first step, per 100 parts by weight of water 5 to 43 parts by weight of trialkoxysilane are added.

### Claim 7 (depends on 1)

The process of claim 1, wherein pH difference is adjusted to be within ±0.5 from the selected value.

### Claim 8 (depends on 1)

The process of claim 1, wherein, in the second step, a solution of alkali metal hydroxide in water or in an alkanol having 1 to 3 carbon atoms is employed to adjust the pH.

### Claim 9 (depends on 1)

The process of claim 1, wherein in the second step, sufficient solution of alkali metal hydroxide is added to ensure that a pH in the range of 6.5 to 9.5 is achieved immediately after addition of alkali metal hydroxide.

### Claim 10 (depends on 1)

The process of claim 1, wherein the temperature of the addition of alkali metal hydroxide in the second step is in the range of 10° C. to 40° C.

### Claim 11 (depends on 1)

The process of claim 1, wherein the particles are isolated by filtration or centrifugation after the third step.

### Claim 12

A process for producing spherical polysilsesquioxane particles in a reproducible manner, the process comprising: in a first step, reacting trialkoxysilane T which contains trialkoxysilanes of formula (I)
RSi(OR1)3 (I),
in which
R represents a hydrocarbon radical having 1 to 16 carbon atoms whose carbon chain may be interrupted by nonadjacent groups —O—,
R1 represents a C1- to C4-alkyl radical,
and which contains chlorine compounds,
by mixing the trialkoxysilane T with acidified water having a pH of at most 6 to afford a hydrolyzate,
in a second step, measuring the pH of the hydrolysate, comparing the pH of the hydrolysate to a selected pH, and when different from the selected pH, adjusting the hydrolysate pH to minimize the difference between the hydrolysate pH and the selected pH to within ±0.5 pH units of the selected pH,
in a third step the hydrolyzate is mixed with a solution of a base in water or C1-C4 alkanol,
and in a fourth step, storing the mixture for at least 2 h before the polysilsesquioxane particles are isolated.

### Claim 13 (depends on 12)

The process of claim 12, wherein the hydrolysate pH is adjusted to within ±0.3 pH units of the selected pH.

### Claim 14 (depends on 12)

The process of claim 12, wherein the hydrolysate pH is adjusted to within ±0.1 pH units of the selected pH.

### Claim 15 (depends on 12)

The process of claim 12, wherein two or more batches are produced, and the pH of the hydrolysate must be adjusted in at least one of the batches.