Patent US4192576A successfully refreshed from Google Patents.
US4192576A
Expired / Lapsed
US
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Ultra-high-index glass microspheres and products made therefrom
Assignee: 3M Co
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Filing: 1978-11-20
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Granted: 1980-03-11
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Expires: 1998-11-20
Abstract
Abstract Glass microspheres having an index of refraction of 2.7 or higher are prepared by (1) forming the microspheres from compositions based principally on 65-85 weight-percent Bi 2 O 3 and 5-35 weight-percent TiO 2 , and (2) rapidly heating the microspheres after they have been initially formed to cause an internal structural rearrangement that raises their index. Such microspheres are useful to form retroreflective products having superior properties and a more simplified construction.
Inventors
- 👤 Chi F. Tung
- 👤 James A. Laird
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:46
CPC Classifications
C; C08; C08K; C08K7/00; C08K7/16; C08K7/18; C08K7/20; C03; C03C; C03C12/00; C03C12/02; C03C3/00; C03C3/12; C03C3/127; C08L; C08L27/00; C08L27/02; C08L27/12; C08L27/16; C08L33/00; C08L33/04; C08L33/06; C08L33/10; C08L33/12; Y; Y10; Y10S; Y10S501/00; Y10S501/90; Y10S501/901
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
71 words
Transparent glass microspheres having an index of refraction of 2.7 or higher comprising 65-85 weight-percent Bi 2 O 3 and 5-35 weight-percent TiO 2 , with any added ingredients totaling up to about one-fourth of the composition by weight; said microspheres having been heat-treated, as indicated by the absence from their temperature profile during differential thermal analysis of an exothermic peak in the temperature interval of about 500° to 650° C.
Claim 2
Dependent Claim
71 words
Transparent glass microspheres having an index of refraction of 2.7 or higher comprising 65-85 weight-percent Bi 2 O 3 and 5-35 weight-percent TiO 2 , with any added ingredients totaling up to about one-fourth of the composition by weight; said microspheres having been heat-treated, as indicated by the absence from their temperature profile during differential thermal analysis of an exothermic peak in the temperature interval of about 500° to 650° C.
Claim 3
Dependent Claim
18 words
Microspheres of claim 1 which comprise 70-80 weight-percent bi 2 O 3 and 20-30 weight-percent TiO 2 .
Claim 4
Dependent Claim
18 words
Microspheres of claim 1 in which any added ingredients total up to about 10 weight-percent of the composition.
Claim 5
Dependent Claim
14 words
Microspheres of claim 1 which include up to 10 weight-percent of a coloring oxide.
Claim 6
Dependent Claim
97 words
Transparent glass microspheres having an index of refraction of 2.7 or higher consisting essentially of 65-85 weight-percent Bi 2 O 3 , 5-35 weight-percent TiO 2 , 0 to 15 weight-percent WO 3 and 0 to 15 weight-percent Nb 2 O 3 ; any ingredients besides Bi 2 O 3 and TiO 2 totaling no more than about one-fourth of the composition by weight; and the microspheres having been heat-treated, as indicated by the absence from their temperature profile during differential thermal analysis of an exothermic peak in the temperature interval of about 550° to 650° C.
Claim 7
Dependent Claim
97 words
Transparent glass microspheres having an index of refraction of 2.7 or higher consisting essentially of 65-85 weight-percent Bi 2 O 3 , 5-35 weight-percent TiO 2 , 0 to 15 weight-percent WO 3 and 0 to 15 weight-percent Nb 2 O 3 ; any ingredients besides Bi 2 O 3 and TiO 2 totaling no more than about one-fourth of the composition by weight; and the microspheres having been heat-treated, as indicated by the absence from their temperature profile during differential thermal analysis of an exothermic peak in the temperature interval of about 550° to 650° C.
Claim 8
Dependent Claim
29 words
Retroreflective sheeting comprising a monolayer of microspheres of claims 1, 2, or 5, a specular layer underlying the microspheres, and a transparent flat-surfaced top layer disposed over the microspheres.
Claim 9
Dependent Claim
19 words
Retroreflective sheeting of claim 6 which further includes a thin transparent vapor-deposited layer between the microspheres and specular layer.
Claim 10
Dependent Claim
25 words
Retroreflective sheeting of claim 6 in which said top layer comprises a mixture of polymeric ingredients to provide a refractive index of less than 1.45.
Claim 11
Dependent Claim
13 words
Reflective lens elements comprising hemispherically reflectorized microspheres of claims 1, 2, or 5.
Claim 12
Dependent Claim
27 words
Reflective lens elements of claim 9 which further include a transparent vapor-deposited layer about 2 micrometers or less in thickness between the microspheres and the hemispherical reflector.
Claim 13
Dependent Claim
18 words
A coating composition comprising a film-forming vehicle and reflective lens elements of claim 9 dispersed in the vehicle.
Claim 14
Dependent Claim
16 words
Transparent film in which hemispherically reflectorized microspheres of claims 1, 2, or 5 are fully embedded.
Claim 15
Dependent Claim
13 words
Film of claim 12 in the form of a coating on a substrate.
Claim 16
Dependent Claim
20 words
Film of claim 12 in which said microspheres carry a thin transparent vapor-deposited layer between them and the hemispherical reflector.
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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) | 1983-03-11 | 1983-09-10 | 1984-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-03-11 | 1987-09-10 | 1988-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-03-11 | 1991-09-10 | 1992-03-11 | $7700.00 | Window Closed / Lapsed |