US3977982A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Controlling viscosity of silica-silicone oil gels
Assignee: Corning Glass Works
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Filing: 1975-01-20
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Granted: 1976-08-31
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Expires: 1995-01-20
Abstract
Abstract The viscosity of a silica-silicone oil gel-like composition useful as a partitioning substance in blood collection tubes can be controlled by first preparing a mixture of a silicone oil and silica particles to form a mixture having a viscosity greater than about 200,000 centistokes, reacting the mixture in an evacuated environment at a temperature ranging from about 175 DEG to 550 DEG C. for a period of time sufficient to reduce the viscosity below about 120,000 centistokes, and then adding a network former to the reaction mixture in a quantity sufficient to increase the viscosity to a range of about 200,000 to 600,000 centistokes, preferably to a range of about 350,000 to 450,000 centistokes.
Inventors
- 👤 William Hertl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 17:21
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/48; G01N33/483; G01N33/487; G01N33/49; G01N33/491; C; C08; C08G; C08G77/00; C08G77/04; C08G77/38; C08K; C08K3/00; C08K3/18; C08K3/20; C08K3/34; C08K3/36; C08K5/00; C08K5/04; C08K5/05; C08K9/00; C08K9/04; C08K9/06; C08L; C08L83/00; C08L83/04; C08L83/10; C08L83/12; Y; Y10; Y10T; Y10T436/00; Y10T436/10; Y10T436/106664; Y10T436/107497
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
142 words
A method of preparing a thixotropic gel-like material useful as a partitioning substance between the serum and clot portions of blood, the method comprising the steps of: a. preparing a mixture of a silicone fluid and silica particles to form a gel-like composition having a specific gravity in the range of about 1.030 to 1.090 and a viscosity above about 200,000 centistokes; b. reacting the mixture in an evacuated environment at a temperature ranging from about 175° to 550°C. for a period of time sufficient to reduce the viscosity to less than about 120,000 centistokes by reaction of a portion of the silica particle surfaces with the silicone fluid; and c. adding a quantity of network former to the reaction products of step (b) to raise the viscosity of the reaction products to a range of about 200,000 to about 600,000 centistokes.
Claim 2
Independent Claim
142 words
A method of preparing a thixotropic gel-like material useful as a partitioning substance between the serum and clot portions of blood, the method comprising the steps of: a. preparing a mixture of a silicone fluid and silica particles to form a gel-like composition having a specific gravity in the range of about 1.030 to 1.090 and a viscosity above about 200,000 centistokes; b. reacting the mixture in an evacuated environment at a temperature ranging from about 175° to 550°C. for a period of time sufficient to reduce the viscosity to less than about 120,000 centistokes by reaction of a portion of the silica particle surfaces with the silicone fluid; and c. adding a quantity of network former to the reaction products of step (b) to raise the viscosity of the reaction products to a range of about 200,000 to about 600,000 centistokes.
Claim 3
Dependent Claim
60 words
The method of claim 1 wherein the silicone fluid consists of a dimethylpolysiloxane having a viscosity ranging from 1000 to 12,500 centistokes, the silica particles consist of finely divided silica particles having a surface area of at least 80 m 2 /gram, and the network former is selected from the group consisting of water, ethylene glycol, and a polysiloxane-polyoxyalkyl copolymer.
Claim 4
Dependent Claim
86 words
The method of claim 2 wherein the polysiloxane-polyoxyalkyl copolymer has the following structure ##EQU3## where the monomeric units are randomly distributed and Me represents -CH 3 ; x represents a number between 80 and 120; y represents a number between 8 and 12; P represents a polyoxyalkyl side chain represented by the formula --(CH.sub.2 --CH.sub.2 --O).sub.m --(CH.sub.2 --CH.sub.2 --CH.sub.2 --O).sub.n -- where the monomeric units are randomly distributed and m represents a number between 20 and 30; and n represents a number between 1 and 30.
Claim 5
Dependent Claim
47 words
The method of claim 2 wherein the viscosity of the mixture of step (a) is between about 200,000 and 1,000,000 centistokes, the reduced viscosity of step (b) is between 50,000 and 120,000 centistokes, and the final viscosity of step (c) is between about 350,000 and 450,000 centistokes.
Claim 6
Dependent Claim
26 words
The method of claim 1 wherein the evacuated environment of step (b) comprises an environment evacuated to a pressure of less than 4 mm. of Hg.
References Cited (Backward Citations)
US3780935A
Cited
US3852194A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-31 | 1980-03-01 | 1980-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-31 | 1984-03-01 | 1984-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-31 | 1988-03-01 | 1988-08-31 | $7700.00 | Window Closed / Lapsed |