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US4420442A
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Manufacturing process for hollow microspheres
Assignee: PQ Corp
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Filing: 1982-09-21
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Granted: 1983-12-13
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Expires: 2002-09-21
Abstract
Abstract More perfect, less porous hollow microspheres can be prepared by spray-drying dispersions of film-forming solids that contain certain organic solvents. The organic solvents are water-miscible and have boiling points of 100° C. or more. The solvent is added just prior to spray drying and the resulting product has fewer cracks and/or holes. This improvement is especially beneficial to preparation systems involving alkali metal silicates and "polysalts."
Inventors
- 👤 Bruce W. Sands
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 01:22
CPC Classifications
B; B01; B01D; B01D1/00; B01D1/16; B01D1/18; C; C04; C04B; C04B18/00; C04B18/02; C04B18/027; Y; Y10; Y10T; Y10T428/00; Y10T428/25; Y10T428/252; Y10T428/29; Y10T428/2982
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
62 words
In the process of preparing hollow microspheres by spray drying an aqueous dispersion of film-forming substance and recovering the product the improvement consisting of adding a porosity reducing amount of a water miscible organic solvent selected from the group consisting of cellosolve, cellosolve acetate, ethyl cellosolve, diglyme and tetraglyme with a boiling point of at least 100° C. prior to spray drying.
Claim 2
Dependent Claim
62 words
In the process of preparing hollow microspheres by spray drying an aqueous dispersion of film-forming substance and recovering the product the improvement consisting of adding a porosity reducing amount of a water miscible organic solvent selected from the group consisting of cellosolve, cellosolve acetate, ethyl cellosolve, diglyme and tetraglyme with a boiling point of at least 100° C. prior to spray drying.
Claim 3
Dependent Claim
29 words
The process of claim 1 wherein about 0.5 to 5.0 parts by weight of the organic solvent for each 100 parts by weight of the film-forming solids is added.
Claim 4
Dependent Claim
68 words
In the process of preparing hollow microspheres by spray drying a solution of alkali metal silicate and a "polysalt" recovering the spray dryer product and further drying, the improvement consisting of adding a porosity-reducing amount of a water-miscible, alkali-stable organic solvent selected from the group consisting of cellosolve, cellosolve acetate, ethyl cellosolve, diglyme and tetraglyme with a boiling point of at least 100° C. prior to spray drying.
Claim 5
Dependent Claim
68 words
In the process of preparing hollow microspheres by spray drying a solution of alkali metal silicate and a "polysalt" recovering the spray dryer product and further drying, the improvement consisting of adding a porosity-reducing amount of a water-miscible, alkali-stable organic solvent selected from the group consisting of cellosolve, cellosolve acetate, ethyl cellosolve, diglyme and tetraglyme with a boiling point of at least 100° C. prior to spray drying.
Claim 6
Dependent Claim
25 words
The process of claim 3 wherein 0.5 to 5.0 pbw of the organic solvent is added for each 100 pbw of silicate and "polysalt" solids.
Claim 7
Dependent Claim
78 words
In the process of preparing hollow microspheres by spray drying a solution selected from the group consisting of sodium silicate and ammonium pentaborate, sodium pentaborate and sodium hexametaphosphate, recovering the spray dryer product and further drying, the improvement consisting of adding a porosity-reducing amount of a water-imiscible, alkali-stable, silicate-compatible organic solvent selected from the group consisting of cellosolve, cellosolve acetate, ethyl cellosolve, diglyme and tetraglyme with a boiling point of at least 100° C. prior to spray drying.
Claim 8
Dependent Claim
78 words
In the process of preparing hollow microspheres by spray drying a solution selected from the group consisting of sodium silicate and ammonium pentaborate, sodium pentaborate and sodium hexametaphosphate, recovering the spray dryer product and further drying, the improvement consisting of adding a porosity-reducing amount of a water-imiscible, alkali-stable, silicate-compatible organic solvent selected from the group consisting of cellosolve, cellosolve acetate, ethyl cellosolve, diglyme and tetraglyme with a boiling point of at least 100° C. prior to spray drying.
Claim 9
Dependent Claim
32 words
The process of claim 5 wherein 0.5 to 5.0 pbw of the organic solvent is added for each 100 pbw of sodium silicate and ammonium pentaborate, sodium pentaborate or sodium hexametaphosphate solids.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-12-12 | 1987-06-13 | 1987-12-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-12 | 1991-06-13 | 1991-12-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-12 | 1995-06-13 | 1995-12-13 | $7700.00 | Window Closed / Lapsed |