US4844976A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Retroreflective sheet coated with silica layer
Assignee: 3M Co
•
Filing: 1988-02-18
•
Granted: 1989-07-04
•
Expires: 2008-02-18
Abstract
Abstract Retroreflective sheeting has been improved by a coating comprising silica and a transparent polymer selected from aliphatic polyurethanes, polyvinyl chloride copolymers having a minor amount of a comonomer containing at least one carboxylic acid or hydroxyl moiety, and acrylic polymers. Silica comprises 10-80 weight percent (10-70% in the case of polyacrylates) of the transparent protective coating. For example, a solution or dispersion of polyurethane is mixed with a silica sol and possibly other ingredients (e.g. wetting agent, UV light absorber and adhesion promoter), and the composition is coated onto the retroreflective sheet and dried. The coated retroreflective sheeting has superior soil and dew repellancy, retaining a higher percentage of original brightness after exposure to dirt and/or dew conditions.
Inventors
- 👤 Tzuli J. Huang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:02
CPC Classifications
C; C08; C08K; C08K3/00; C08K3/34; C08K3/36; B; B05; B05D; B05D3/00; B05D3/002; C08G; C08G18/00; C08G18/06; C08G18/08; C08G18/0804; C08G18/0819; C08G18/0823; C08G18/70; C08G18/72; C08G18/74; C08G18/75; C08G18/758; C08G18/83; C08G18/833; C08J; C08J3/00; C08J3/20; C08J3/205; C08J3/21; C08J3/215; C08J7/00; C08J7/12; C08J7/123; C08L; C08L75/00; C08L75/04; C08L83/00; C09; C09D; C09D175/00; C09D175/04; E; E01; E01F; E01F9/00; E01F9/50; E01F9/506; E01F9/512; E01F9/553; G; G02; G02B; G02B1/00; G02B1/10; G02B1/14; G02B1/18; G02B5/00; G02B5/12; C08J2375/00; C08J2375/04; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10T; Y10T428/00; Y10T428/25; Y10T428/259; Y10T428/29; Y10T428/2982
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
53 words
A retroreflective sheet having a transparent, protective coating on the surface intended to be the light incident surface comprising silica and a transparent polymer selected from the group consisting of acrylic polymers having a glass transition temperature of -20° to 60° C. wherein the silica comprises about 10-70 weight percent of the coating.
Claim 2
Dependent Claim
53 words
A retroreflective sheet having a transparent, protective coating on the surface intended to be the light incident surface comprising silica and a transparent polymer selected from the group consisting of acrylic polymers having a glass transition temperature of -20° to 60° C. wherein the silica comprises about 10-70 weight percent of the coating.
Claim 3
Dependent Claim
16 words
The retroreflective sheet of claim 1 which further comprises a minor amount of hydrophilic polysilozane polymer.
Claim 4
Dependent Claim
18 words
The retroreflective sheet of claim 1 wherein the silica comprises particles less than 50 nm in particle size.
Claim 5
Dependent Claim
9 words
The retroreflective sheet of claim 1 which is hydrophilic.
Claim 6
Dependent Claim
24 words
The retroreflective sheet of claim 1 wherein the transparent polymer is an acrylic polymer which is a copolymer of methyl methacrylate and butyl methacrylate.
Claim 7
Dependent Claim
19 words
The retroreflective sheet of claim 1 wherein the transparent polymer comprises a mixture of aliphatic polyurethane and acrylic polymers.
Claim 8
Dependent Claim
16 words
The retroreflective sheet of claim 1 wherein the thickness of the protective coating is 2.5-150 micrometers.
Claim 9
Dependent Claim
26 words
The retroreflective sheet of claim 1 in which the protective coating remains transparent when the sheet is wet with water after having been immersed in water.
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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) | 1992-07-03 | 1993-01-02 | 1993-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-03 | 1997-01-02 | 1997-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-03 | 2001-01-02 | 2001-07-04 | $7700.00 | Window Closed / Lapsed |