# US 5,710,300 A · Siloxy phosphonate as stabilizing agent for polydiorganosiloxanes

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- Number: US 5,710,300 A
- Document ID: US5710300A
- Status: Granted
- Kind: A
- Application number: 08/827,822
- Filed: 1997-04-11
- Granted: 1998-01-20
- Earliest claimed: 1997-04-11
- Assignees: Dow Corning Corporation
- Inventors: Daniel Graiver; Arnold Wade Lomas
- Web page: https://patentgrep.com/patent/US5710300A

## CPC

- C08G 77/395: containing phosphorus
- C08G 77/32: Post-polymerisation treatment
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS

## Abstract

A method for stabilizing a mixture comprising a polydiorganosiloxane and an alkali metal. The method comprises contacting a polydiorganosiloxane and an alkali metal with a siloxy phosphonate described by formula ##STR1## where each R.sup.1, R.sup.2, and R.sup.3 is an independently selected hydrocarbon comprising one to about 12 carbon atoms, n=0 or 1, and x, y, and z are integers, where x=1 to 1000, y=0 to 1000, and z=0 to 1000.

## Claims

### Claim 1

A method for stabilizing polydiorganosiloxanes, the method comprising: contacting a mixture comprising a polydiorganosiloxane and an alkali metal with a stabilizing amount of a siloxy phosphonate described by formula ##STR5## where each R.sup.1, R.sup.2, and R.sup.3 is an independently selected hydrocarbon group comprising one to about twelve carbon atoms, n=0 or 1, x, y, and z are integers, where x=1 to 1000, y=0 to 1000, and z=0 to 1000.

### Claim 2 (depends on 1)

A method according to claim 1, where the polydiorganosiloxane is selected from the group consisting of trimethylsiloxy end-terminated polydimethylsiloxane, vinyldimethylsiloxy end-terminated polydimethylsiloxane, vinyldimethylsiloxy end-terminated polydimethylsiloxane having pendant vinyl groups attached to silicon, dimethylhydroxysiloxy end-terminated polydimethylsiloxane, dimethylhydrosiloxy end-terminated polydimethylsiloxane having pendant hydrogens attached to silicon, or (3,3,3-trifluoropropyl)dimethylsiloxy end-terminated polydiorganosiloxane having about 50 percent of pendant organic groups attached to silicon comprising methyl and the remainder pendant organic groups comprising 3,3,3-trifluoropropyl.

### Claim 3 (depends on 1)

A method according to claim 1, where the alkali metal is potassium.

### Claim 4 (depends on 1)

A method according to claim 1, where R.sup.1 is an unsubstituted hydrocarbon group comprising less than about seven carbon atoms.

### Claim 5 (depends on 1)

A method according to claim 1, where R.sup.1 comprises about one to two carbon atoms.

### Claim 6 (depends on 1)

A method according to claim 1, where R.sup.3 is vinyl.

### Claim 7 (depends on 1)

A method according to claim 1, where R.sup.2 is methyl.

### Claim 8 (depends on 1)

A method according to claim 1, where the siloxy phosphonate is a mixture of mono and bis(polysiloxy) phosphonates.

### Claim 9 (depends on 1)

A method according to claim 1, where the siloxy phosphonate provides about 0.1:1 to 10:1 mole ratio of phosphorous to alkali metal atoms.

### Claim 10 (depends on 1)

A method according to claim 1, where the siloxy phosphonate provides about 0.5:1 to 2:1 mole ratio of phosphorous to alkali metal atoms.

### Claim 11 (depends on 1)

A method according to claim 1, where the siloxy phosphonate provides at least one phosphorous atom per each alkali metal atom.

### Claim 12 (depends on 1)

A method according to claim 1, where the mixture is contacted with the siloxy phosphonate at a temperature within a range of about 100.degree. C. to 300.degree. C.

### Claim 13 (depends on 1)

A method according to claim 1, where the mixture is contacted with the siloxy phosphonate at a temperature within a range of about 225.degree. C. to 275.degree. C.

### Claim 14 (depends on 1)

A method according to claim 1, further comprising contacting the mixture with carbon dioxide gas before contact with the siloxy phosphonate .