US4786302A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing tubular silica glass
Assignee: Seiko Epson Corp
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Filing: 1987-07-13
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Granted: 1988-11-22
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Expires: 2007-07-13
Abstract
Abstract A sol-gel process for preparing dimensionally precise tubular silica glass articles wherein a solution having a specific gravity higher than the specific gravity of the sol solution is placed in a cylindrical container with the sol solution is provided. The container is rotated around its axis and the high specific gravity solution becomes aligned adjacent the inner wall of the cylindrical container due to the effect of centrifugal forces acting on the high specific gravity solution. The sol solution becomes aligned adjacent the inner surface of the high specific gravity solution. The tubular wet gel formed from the sol solution has a uniform thickness and a highly precise round cross-section. The dimensional precision of the wet gel is maintained by rotating the wet gel during drying in order to prevent warping.
Inventors
- 👤 Haruo Osafune
- 👤 Sadao Kanbe
- 👤 Teiichiro Mori
- 👤 Masahisa Ikejiri
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:03
CPC Classifications
C; C03; C03B; C03B37/00; C03B37/01; C03B37/012; C03B37/014; C03B37/016; C03B19/00; C03B19/12; C03C; C03C1/00; C03C1/006; Y; Y02; Y02P; Y02P40/00; Y02P40/50; Y02P40/57; Y10; Y10S; Y10S65/00; Y10S65/901
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
126 words
A method of preparing tubular silica glass, comprising; preparing a sol of a metal alkoxide hydrolyzed with an acid catalyst; adding ultrafine particles of silica to the sol to yield a sol solution; placing the sol solution into a cylindrical container; placing a liquid having a specific gravity higher than the specific gravity of the sol solution into the cylindrical container, said liquid having a higher specific gravity being immiscible with the sol solution, does not dissolve the sol solution and in which the sol solution does not dissolve; gelling the sol solution by rotating the container about the cylindrical axis to form a tubular wet gel; drying the tubular wet gel to a dry gel; and, sintering the dry gel to yield tubular silica glass.
Claim 2
Independent Claim
126 words
A method of preparing tubular silica glass, comprising; preparing a sol of a metal alkoxide hydrolyzed with an acid catalyst; adding ultrafine particles of silica to the sol to yield a sol solution; placing the sol solution into a cylindrical container; placing a liquid having a specific gravity higher than the specific gravity of the sol solution into the cylindrical container, said liquid having a higher specific gravity being immiscible with the sol solution, does not dissolve the sol solution and in which the sol solution does not dissolve; gelling the sol solution by rotating the container about the cylindrical axis to form a tubular wet gel; drying the tubular wet gel to a dry gel; and, sintering the dry gel to yield tubular silica glass.
Claim 3
Dependent Claim
27 words
The method of claim 1, wherein the high specific gravity liquid is a halogen-containing organic compound with the halogen atoms on the same or adjacent carbon atoms.
Claim 4
Dependent Claim
41 words
The method of claim 1, wherein the solution having a specific gravity higher than the specific gravity of the sol solution is selected from the group consisting of FLOURINERT, tetrachlorodifluoroethane, trichlorotrifluoroethane, carbon tetrachloride, tetrachloroethylene, bromoform, dibromoethane, diiode methane and mixtures thereof.
Claim 5
Dependent Claim
44 words
The method of claim 1, further comprising; extracting the high specific gravity liquid from the cylindrical container after the sol solution is gelled to a tubular wet gel and; filling the container with an aqueous alcohol solution prior to drying the tubular wet gel.
Claim 6
Dependent Claim
27 words
The method of claim 4, wherein the aqueous alcohol solution is a solution of water and a simple alcohol having between about one and ten carbon atoms.
Claim 7
Dependent Claim
10 words
The method of claim 5, wherein the alcohol is ethanol.
Claim 8
Dependent Claim
38 words
The method of claim 1, wherein the rotation of the rotating cylindrical container is controlled so that the maximum centrifugal force to which the sol solution is subjected is less than about 1,000 G (G=980 cm/second 2 ).
Claim 9
Dependent Claim
20 words
The method of claim 1, wherein rotation of the tubular wet gel is continued after the sol solution is gelled.
Claim 10
Dependent Claim
19 words
The method of claim 8, wherein rotation is continued for a period between about 30 minutes and 30 hours.
Claim 11
Dependent Claim
17 words
The method of claim 8, wherein the rotation rate is at least about 0.1 rotations per minute.
Claim 12
Dependent Claim
15 words
The method of claim 1, wherein the tubular wet gel is rotated while being dried.
Claim 13
Dependent Claim
21 words
The method of claim 11, wherein the rotation rate is between about 1 rotation per day and 100 rotations per minute.
Claim 14
Dependent Claim
30 words
The method of claim 1, wherein the metal alkoxide is silicon alkoxide having the general formula Si(OR) 4 wherein R is an alkyl group having one to six carbon atoms.
Claim 15
Dependent Claim
12 words
The method of claim 13, wherein the silicon alkoxide is silicon ethoxide.
Claim 16
Dependent Claim
35 words
The method of claim 1, wherein the ultrafine particle silica is added to the acid hydrolyzed metal alkoxide solution in an amount from about 0.2 to 5 mols of silica per mol of metal alkoxide.
Claim 17
Dependent Claim
54 words
The method of claim 1, wherein the ultrafine particles of silica are selected from the group consisting of white carbon obtained by hydrolyzing SiC1 4 using an oxygen-hydrogen flame burner, ultrafine particle silica obtained by a dry method using sodium silicate and ultrafine particle silica obtained by hydrolyzing silicon alkoxide with a basic catalyst.
Claim 18
Dependent Claim
39 words
The method of claim 1, wherein the ultrafine particle silica is fumed silica obtained by hydrolyzing silicon alkoxide with a basic catalyst and concentrating the solution of silicon alkoxide hydrolyzed with a basic catalyst to increase the silica concentration.
Claim 19
Dependent Claim
37 words
The method of claim 1, wherein ultrasonic vibration is applied to the sol solution to which ultrafine particles of silica have been added in order to uniformly disperse the ultrafine particles of silica in the sol solution.
Claim 20
Dependent Claim
25 words
The method of claim 1, wherein the pH of the sol solution is adjusted to between about 3 and 6 by addition of a base.
Claim 21
Dependent Claim
25 words
The method of claim 1, wherein sintering the dry gel includes (1) removing absorbed water, (2) removing carbon and (3) making the dry gel non-porous.
Claim 22
Dependent Claim
57 words
The method of claim 20, wherein absorbed water is removed by at least one step of heating the dry gel to a first selected temperature between about 20° and 400° C. at a rate of less than about 400° C. per hour and maintaining said dry gel at the first selected temperature for at least one hour.
Claim 23
Dependent Claim
58 words
The method of claim 20, wherein carbon is removed by at least one step of heating the dry gel to a second selected temperature between about 400° and 1100° C. at a heating rate of between about 50° and 400° C. per hour and maintaining the dry gel at said second selected temperature for at least 3 hours.
Claim 24
Dependent Claim
45 words
The method of claim 20, wherein the dry gel is made non-porous by at least one step of heating the dry gel to a third selected temperature between about 1000° and 1400° C. at a heating rate between about 50° and 400° C. per hour.
Claim 25
Dependent Claim
21 words
The method of claim 20, wherein the step of removing carbon is at least partially performed in an atmosphere including oxygen.
Claim 26
Dependent Claim
21 words
The method of claim 20, wherein the step of making the dry gel non-porous is at least partially performed under vacuum.
Claim 27
Dependent Claim
23 words
The method of claim 20, wherein the step of making the dry gel non-porous is at least partially performed in a helium atmosphere.
Claim 28
Dependent Claim
21 words
The method of claim 20, wherein sintering is at least partially performed in an atmosphere including an OH group removing agent.
Claim 29
Dependent Claim
79 words
The method of claim 1, wherein the dry gel is sintered by heating the dry gel in an atmosphere selected from the group consisting of oxygen and an inert gas containing oxygen, heating the oxidized dry gel in an atmosphere including OH group removing agent and sintering the dry gel from which OH groups have been removed in a vacuum or in a helium atmosphere at least until the fine pores at the surface of the gel are closed.
Claim 30
Dependent Claim
49 words
The method of claim 28, wherein the sintering process further includes the step of heating the dry gel in an atmosphere selected from the group consisting of oxygen and an inert gas containing oxygen after heating the oxidized dry gel in an atmosphere containing an OH group removing agent.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-11-22 | 1992-05-23 | 1992-11-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-22 | 1996-05-23 | 1996-11-22 | $3760.00 | Window Closed / Lapsed |
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