US4772511A
Expired / Lapsed
US
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Transparent non-vitreous zirconia microspheres
Assignee: 3M Co
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Filing: 1985-11-22
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Granted: 1988-09-20
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Expires: 2005-11-22
Abstract
Abstract Solid, transparent, non-vitreous, zirconia and zirconia-silica ceramic microspheres, useful as lens elements in retroreflective pavement markings. The microspheres are characterized by: (a) containing at least one additive metal oxide selected from alumina, magnesia, yttria and mixtures thereof; (b) an index of refraction greater than 1.6; and (c) being virtually free of cracks. These microspheres are formed by a sol-gel technique of extractive gelation (extracting carboxylic acid away from zirconyl carboxylate) of a sol in liquid medium such as hot peanut oil. The microspheres of this ceramic composition have been made with relatively large diameters, (e.g. 200-1000 micrometers) making them quite useful as lens elements in pavement marking sheet materials.
Inventors
- 👤 Thomas E. Wood
- 👤 Roger W. Lange
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:41
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/48; C04B35/622; C04B35/62227; C04B35/62231; C04B35/6225; C01; C01G; C01G25/00; C01G25/02; C04B35/481; C04B35/624; G; G02; G02B; G02B5/00; G02B5/12; G02B5/126; G02B5/128; C01P; C01P2004/00; C01P2004/30; C01P2004/32; C01P2004/80; C01P2004/82; C01P2006/00; C01P2006/60; C01P2006/90; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10S501/00; Y10S501/90; Y10S501/901; Y10T; Y10T428/00; Y10T428/25; Y10T428/252; Y10T428/256; Y10T428/257; Y10T428/258; Y10T428/259; Y10T428/29; Y10T428/2982
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
75 words
A solid, transparent, non-vitreous, ceramic spheroid substantially free of cracks, having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria, and mixtures thereof, and which can in addition contain silica wherein, for those spheroids containing silica, the molar ratio of zirconia to silica is greater than 1.8.
Claim 2
Dependent Claim
75 words
A solid, transparent, non-vitreous, ceramic spheroid substantially free of cracks, having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria, and mixtures thereof, and which can in addition contain silica wherein, for those spheroids containing silica, the molar ratio of zirconia to silica is greater than 1.8.
Claim 3
Dependent Claim
34 words
The solid, transparent, ceramic spheroid of claim 1 wherein the molar ratio of zirconia to the sum of the moles of the other metal oxides is within the range of about 1.0:0.005 to 1.0:5.0.
Claim 4
Dependent Claim
15 words
The solid, transparent, ceramic spheroid of claim 2 having a refractive index greater than 1.83.
Claim 5
Dependent Claim
24 words
The transparent, ceramic spheroid of claim 1 wherein the predominant crystal structure of the zirconia is selected from the following structures: tetragonal and cubic.
Claim 6
Dependent Claim
15 words
The solid, transparent, ceramic spheroid of claim 1 which further comprises an amorphous silica phase.
Claim 7
Dependent Claim
24 words
The solid, transparent, ceramic spheroid of claim 5 wherein the molar ratio of zirconia to silica is in the range of 10:1 to 1.8:1.
Claim 8
Dependent Claim
17 words
The solid, transparent, ceramic spheroid of claim 1 wherein average grain size is less than 1000 angstroms.
Claim 9
Dependent Claim
15 words
The solid, transparent, ceramic spheroid of claim 1 having a diameter greater than 125 micrometers.
Claim 10
Dependent Claim
22 words
A sheet material comprising polymeric binder film in which is embedded a multiplicity of the solid, transparent, ceramic spheroids of claim 1.
Claim 11
Dependent Claim
31 words
A pavement marking sheet material comprising: a. a base sheet adherable to a roadway surface; and b. the sheet material of claim 9 adhered to one surface of the base sheet.
Claim 12
Dependent Claim
34 words
A retroreflective sheet material comprising a polymeric binder film in which the spheroids of claim 1 are embedded and a reflecting means, there being a light path through the spheroids to the reflecting means.
Claim 13
Dependent Claim
23 words
A pavement marking comprising a layer of polymeric binder material supported on a roadway surface and the spheroids of claim 1 embedded therein.
Claim 14
Dependent Claim
77 words
A solid, transparent, non-vitreous, ceramic spheroid substantially free of cracks, having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia, silica, and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria, and mixtures thereof, wherein the weight of the other metal oxides combined is greater than 30 percent of the combined weight of zirconia and silica in the spheroid.
Claim 15
Dependent Claim
77 words
A solid, transparent, non-vitreous, ceramic spheroid substantially free of cracks, having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia, silica, and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria, and mixtures thereof, wherein the weight of the other metal oxides combined is greater than 30 percent of the combined weight of zirconia and silica in the spheroid.
Claim 16
Dependent Claim
34 words
The solid, transparent, non-vitreous, ceramic spheroid of claim 13 wherein the molar ratio of zirconia to the sum of the moles of the other metal oxides is within the range of 1.0:0.005 to 1.0:5.0.
Claim 17
Dependent Claim
15 words
The solid, transparent, ceramic spheroid of claim 13 having a diameter greater than 125 micrometers.
Claim 18
Dependent Claim
22 words
A sheet material comprising polymeric binder film in which is embedded a multiplicity of the solid, transparent, ceramic spheroids of claim 13.
Claim 19
Dependent Claim
31 words
A pavement marking sheet material comprising: a. a base sheet adherable to a roadway surface; and b. the sheet material of claim 16 adhered to one surface of the base sheet.
Claim 20
Dependent Claim
37 words
A retroreflective sheet material comprising a polymeric binder film in which a monolayer of the spheroids of claim 13 is embedded and a reflecting means, there being a light path through the spheroids to the reflecting means.
Claim 21
Dependent Claim
23 words
A pavement marking comprising a layer of polymeric binder material supported on a roadway surface and the spheroids of claim 13 embedded therein.
Claim 22
Dependent Claim
50 words
A solid, transparent, non-vitreous, ceramic spheroid substantially free of cracks and having an index of refraction greater than 1.6, having a diameter of at least 125 micrometers and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria and mixtures thereof.
Claim 23
Dependent Claim
50 words
A solid, transparent, non-vitreous, ceramic spheroid substantially free of cracks and having an index of refraction greater than 1.6, having a diameter of at least 125 micrometers and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria and mixtures thereof.
Claim 24
Dependent Claim
33 words
The solid, transparent, ceramic spheroid of claim 20 wherein the molar ratio of zirconia to the sum of the moles of the other metal oxides is within the range of 1.0:0.005 to 1.0:5.0.
Claim 25
Dependent Claim
15 words
The solid, transparent, ceramic spheroid of claim 21 having a refractive index greater than 1.83.
Claim 26
Dependent Claim
15 words
The solid, transparent, ceramic spheroid of claim 20 which further comprises an amorphous silica phase.
Claim 27
Dependent Claim
22 words
A sheet material comprising polymeric binder film in which is embedded a multiplicity of the solid, transparent, ceramic spheroids of claim 20.
Claim 28
Dependent Claim
31 words
A pavement marking sheet material comprising: a. a base sheet adherable to a roadway surface; and b. the sheet material of claim 24 adhered to one surface of the base sheet.
Claim 29
Dependent Claim
37 words
A retroreflective sheet material comprising a polymeric binder film in which a monolayer of the spheroids of claim 20 is embedded and a reflecting means, there being a light path through the spheroids to the reflecting means.
Claim 30
Dependent Claim
23 words
A pavement marking comprising a layer of polymeric binder material supported on a roadway surface and the spheroids of claim 20 embedded therein.
Claim 31
Dependent Claim
63 words
A pavement marking comprising a layer of polymeric binder material in which is embedded a multiplicity of solid, transparent, non-vitreous, ceramic spheroids having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria and mixtures thereof.
Claim 32
Dependent Claim
63 words
A pavement marking comprising a layer of polymeric binder material in which is embedded a multiplicity of solid, transparent, non-vitreous, ceramic spheroids having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria and mixtures thereof.
Claim 33
Dependent Claim
63 words
A pavement marking comprising a layer of polymeric binder material in which is embedded a multiplicity of solid, transparent, non-vitreous, ceramic spheroids having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria and mixtures thereof.
Claim 34
Dependent Claim
63 words
A pavement marking comprising a layer of polymeric binder material in which is embedded a multiplicity of solid, transparent, non-vitreous, ceramic spheroids having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria and mixtures thereof.
Claim 35
Dependent Claim
61 words
A pavement marking comprising a layer of polymeric binder material in which is embedded a multiplicity of solid, transparent, non-vitreous, ceramic spheroids having a diameter of at least 125 micrometers and an index of refraction greater than 1.6 and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria and mixtures thereof.
Claim 36
Dependent Claim
61 words
A pavement marking comprising a layer of polymeric binder material in which is embedded a multiplicity of solid, transparent, non-vitreous, ceramic spheroids having a diameter of at least 125 micrometers and an index of refraction greater than 1.6 and comprising crystalline zirconia and at least one other metal oxide selected from the group consisting of alumina, magnesia, yttria and mixtures thereof.
Claim 37
Dependent Claim
46 words
A solid, transparent, non-vitreous, ceramic spheroid substantially free of cracks and having an index of refraction greater than 1.6, having a diameter of at least 125 micrometers and comprising crystalline zirconia, alumina, and silica wherein the molar ratio of zirconia to silica is greater than 1.8.
Claim 38
Dependent Claim
46 words
A solid, transparent, non-vitreous, ceramic spheroid substantially free of cracks and having an index of refraction greater than 1.6, having a diameter of at least 125 micrometers and comprising crystalline zirconia, alumina, and silica wherein the molar ratio of zirconia to silica is greater than 1.8.
Claim 39
Dependent Claim
59 words
A pavement marking comprising a layer of polymeric binder material in which is embedded a multiplicity of solid, transparent, non-vitreous, ceramic spheroids having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia, alumina and silica wherein the molar ratio of zirconia to silica is greater than 1.8.
Claim 40
Dependent Claim
59 words
A pavement marking comprising a layer of polymeric binder material in which is embedded a multiplicity of solid, transparent, non-vitreous, ceramic spheroids having substantially no open porosity detectable by BET nitrogen technique and an index of refraction greater than 1.6 and comprising crystalline zirconia, alumina and silica wherein the molar ratio of zirconia to silica is greater than 1.8.
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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) | 1991-09-20 | 1992-03-21 | 1992-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-20 | 1996-03-21 | 1996-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-20 | 2000-03-21 | 2000-09-20 | $7700.00 | Window Closed / Lapsed |