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US5028270A
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Freeze-stabilized silica sol and its use as liquid for phosphate-based embedding compositions
Assignee: BK Giulini GmbH
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Filing: 1989-03-23
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Granted: 1991-07-02
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Expires: 2009-03-23
Abstract
Abstract An aqueous silicic acid sol which is freeze-stabilized and which is useful for the production of phosphate-based embedding compositions used in dental technology, the aqueous silicic acid sol including from 25 to 50 weight percent of silicon dioxide; and from 2 to 10 weight % of a compound which is one of urea or a urea derivative and which has the general formula: <IMAGE> wherein X and Y are groups selected from the group consisting of an -NH2 group and an -NHR group, in which R is an alkyl radical having from 1 to 4 carbon atoms.
Inventors
- 👤 Hans-Joachim Forster
- 👤 Josef Gotzig
- 👤 Jorg Brenn
- 👤 Wolfgang Tucholke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:48
CPC Classifications
A; A61; A61K; A61K6/00; C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/14; C01B33/146; C01B33/148; C01B33/1485
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
111 words
An aqueous silicic acid sol which is freeze-stabilized by inclusion therein of an antifreeze material and which is useful in dental technology for the production of phosphate-based embedding compositions, the aqueous silicic acid sol comprising: water; from 25 to 50 weight percent of silicon dioxide; and from 2 to 10 weight % of a compound which functions as an antifreeze material, which is one of urea or a urea derivative, and which has the general formula: ##STR6## wherein X and Y are groups selected from the group consisting of an --NH 2 group and an --NHR group in which R is an alkyl radical having from 1 to 4 carbon atoms.
Claim 2
Dependent Claim
111 words
An aqueous silicic acid sol which is freeze-stabilized by inclusion therein of an antifreeze material and which is useful in dental technology for the production of phosphate-based embedding compositions, the aqueous silicic acid sol comprising: water; from 25 to 50 weight percent of silicon dioxide; and from 2 to 10 weight % of a compound which functions as an antifreeze material, which is one of urea or a urea derivative, and which has the general formula: ##STR6## wherein X and Y are groups selected from the group consisting of an --NH 2 group and an --NHR group in which R is an alkyl radical having from 1 to 4 carbon atoms.
Claim 3
Dependent Claim
20 words
The aqueous silicic acid sol as defined in claim 1, containing from 5 to 7 weight % of said compound.
Claim 4
Dependent Claim
15 words
The aqueous silicic acid sol as defined in claim 2, wherein said compound is urea.
Claim 5
Dependent Claim
32 words
The aqueous silicic acid sol as defined in claim 2, wherein said compound is a urea derivative selected from the group consisting of N-methyl urea, N-ethyl urea, N,N'-dimethyl urea, and mixtures thereof.
Claim 6
Dependent Claim
20 words
The aqueous silicic acid sol as defined in claim 2, containing from 35 to 45 weight % of silicon dioxide.
Claim 7
Dependent Claim
15 words
The aqueous silicic acid sol as defined in claim 5, wherein said compound is urea.
Claim 8
Dependent Claim
32 words
The aqueous silicic acid sol as defined in claim 5, wherein said compound is a urea derivative selected from the group consisting of N-methyl urea, N-ethyl urea, N,N'-dimethyl urea and mixtures thereof.
Claim 9
Dependent Claim
20 words
The aqueous silicic acid sol as defined in claim 1, containing from 35 to 45 weight % of silicon dioxide.
Claim 10
Dependent Claim
15 words
The aqueous silicic acid sol as defined in claim 8, wherein said compound is urea.
Claim 11
Dependent Claim
32 words
The aqueous silicic acid sol as defined in claim 8, wherein said compound is a urea derivative selected from the group consisting of N-methyl urea, N-ethyl urea, N,N'-dimethyl urea, and mixtures thereof.
Claim 12
Dependent Claim
31 words
The aqueous silicic acid as defined in claim 1, wherein said compound is a urea derivative selected from the group consisting of N-methyl urea, N-ethyl urea, N,N'-dimethyl urea, and mixtures thereof.
Claim 13
Dependent Claim
16 words
The aqueous silicic acid sol as defined in claim 1, wherein said compound is N-methyl urea.
Claim 14
Dependent Claim
16 words
The aqueous silicic acid sol as defined in claim 1, wherein said compound is N-ethyl urea.
Claim 15
Dependent Claim
16 words
The aqueous silicic acid sol as defined in claim 1, wherein said compound is N,N'-dimethyl urea.
Claim 16
Dependent Claim
15 words
The aqueous silicic acid sol as defined in claim 1, wherein said compound is urea.
Claim 17
Dependent Claim
127 words
An embedding composition which is phosphate-based and which is useful in dental technology to produce refractory molds for precision casting of metal articles, the embedding composition comprising: a binder which is phosphate-based; and an aqueous silicic acid sol which is freeze-stabilized by inclusion therein of an antifreeze material and which comprises: water; from 25 to 50 weight percent of silicon dioxide; and from 2 to 10 weight % of a compound which functions as an antifreeze material, which is one of urea or a urea derivative, and which has the general formula: ##STR7## wherein X and Y are groups selected from the group consisting of an --NH 2 group and an --NHR group in which R is an alkyl radical having from 1 to 4 carbon atoms.
Claim 18
Dependent Claim
127 words
An embedding composition which is phosphate-based and which is useful in dental technology to produce refractory molds for precision casting of metal articles, the embedding composition comprising: a binder which is phosphate-based; and an aqueous silicic acid sol which is freeze-stabilized by inclusion therein of an antifreeze material and which comprises: water; from 25 to 50 weight percent of silicon dioxide; and from 2 to 10 weight % of a compound which functions as an antifreeze material, which is one of urea or a urea derivative, and which has the general formula: ##STR7## wherein X and Y are groups selected from the group consisting of an --NH 2 group and an --NHR group in which R is an alkyl radical having from 1 to 4 carbon atoms.
Claim 19
Dependent Claim
97 words
The process of freeze-stabilizing an aqueous silicic acid sol comprised of water and from 25 to 50 weight % of silicon dioxide, the process comprising: admixing in the aqueous silicic acid sol from 2 to 10 weight % of a compound which functions as an antifreeze material, which is one of urea or a urea derivative, and which has the general formula: ##STR8## wherein X and Y are groups selected from the group consisting of an --NH 2 group and an --NHR group in which R is an alkyl radial having from 1 to 4 carbon atoms.
Claim 20
Dependent Claim
97 words
The process of freeze-stabilizing an aqueous silicic acid sol comprised of water and from 25 to 50 weight % of silicon dioxide, the process comprising: admixing in the aqueous silicic acid sol from 2 to 10 weight % of a compound which functions as an antifreeze material, which is one of urea or a urea derivative, and which has the general formula: ##STR8## wherein X and Y are groups selected from the group consisting of an --NH 2 group and an --NHR group in which R is an alkyl radial having from 1 to 4 carbon atoms.
Claim 21
Dependent Claim
104 words
The process of controlling expansion-upon-setting of a phosphate-based embedding composition comprised of an aqueous silicic acid sol including water and from 25 to 50 weight % of silicon dioxide, the process comprising: admixing in the aqueous silicic acid sol from 2 to 10 weight % of a compound which functions as an antifreeze material, which is one of urea or a urea derivative, and which has the general formula: ##STR9## wherein X and Y are groups selected from the group consisting of an --NH 2 group and an --NHR group in which R is an alkyl radical having from 1 to 4 carbon atoms.
Claim 22
Dependent Claim
104 words
The process of controlling expansion-upon-setting of a phosphate-based embedding composition comprised of an aqueous silicic acid sol including water and from 25 to 50 weight % of silicon dioxide, the process comprising: admixing in the aqueous silicic acid sol from 2 to 10 weight % of a compound which functions as an antifreeze material, which is one of urea or a urea derivative, and which has the general formula: ##STR9## wherein X and Y are groups selected from the group consisting of an --NH 2 group and an --NHR group in which R is an alkyl radical having from 1 to 4 carbon atoms.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-07-01 | 1994-12-31 | 1995-07-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-07-01 | 1998-12-31 | 1999-07-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-07-01 | 2002-12-31 | 2003-07-02 | $7700.00 | Window Closed / Lapsed |