Patent US4725494A successfully refreshed from Google Patents.
US4725494A
Expired / Lapsed
US
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Retroreflective sheeting
Assignee: 3M Co
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Filing: 1985-05-08
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Granted: 1988-02-16
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Expires: 2005-05-08
Abstract
Abstract A retroreflective sheeting utilizing a particular polymer as the bead bond layer is disclosed. The polymeric bead bond comprises urethane and urea linkages, and has a stage prior to thermosetting in which it may be softened by the application of heat and in which it has a relatively nontacky character. The retroreflective sheeting disclosed possesses the unique combination of high reflectance and superior exterior durability.
Inventors
- 👤 Louis C. Belisle
- 👤 Thomas R. Borden
- 👤 Raymond E. Grunzinger, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:03
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/12; G02B5/126; G02B5/128; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10T; Y10T428/00; Y10T428/25; Y10T428/252; Y10T428/254; Y10T428/31504; Y10T428/31551; Y10T428/31598; Y10T428/31601
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
132 words
Improved retroreflective sheeting comprising (a) a monolayer of transparent microspheres, (b) said microspheres partially embedded in a polymeric layer which has been reacted to a substantially infusible and insoluble state, and (c) a specularly reflective layer underlying said transparent microspheres; wherein the improvement comprises that said polymeric layer comprises urethane or urea linkages, and said polymeric layer has a stage prior to said reaction in which it may be softened by the application of heat and in which it exhibits a rolling ball distance of greater than about 200 cm when measured according to the "Tack Rolling Ball Method," PSTC-6, as described herein, at 23° C. and 50% relative humidity, and said transparent microspheres are present in said sheeting in a concentration of at least about 80 percent of the theoretical maximum.
Claim 2
Dependent Claim
132 words
Improved retroreflective sheeting comprising (a) a monolayer of transparent microspheres, (b) said microspheres partially embedded in a polymeric layer which has been reacted to a substantially infusible and insoluble state, and (c) a specularly reflective layer underlying said transparent microspheres; wherein the improvement comprises that said polymeric layer comprises urethane or urea linkages, and said polymeric layer has a stage prior to said reaction in which it may be softened by the application of heat and in which it exhibits a rolling ball distance of greater than about 200 cm when measured according to the "Tack Rolling Ball Method," PSTC-6, as described herein, at 23° C. and 50% relative humidity, and said transparent microspheres are present in said sheeting in a concentration of at least about 80 percent of the theoretical maximum.
Claim 3
Dependent Claim
45 words
The retroreflective sheeting of claim 1 wherein said polymeric layer at a stage prior to said reaction, comprises a polymeric compound having isocyanate groups incorporated therein, wherein a substantial portion of the free isocyanate groups are masked by agents which may be removed by heating.
Claim 4
Dependent Claim
32 words
The retroreflective sheeting of claim 2 wherein said polymeric layer has a softening range between the crystalline melting point for said polymeric compound and the minimum dissociation temperature for said masking agent.
Claim 5
Dependent Claim
17 words
The retroreflective sheeting of claim 3 wherein said softening range is between about 45° and 90° C.
Claim 6
Dependent Claim
130 words
The retroreflective sheeting of claim 1 wherein said polymeric layer at a stage prior to said reaction comprises a polymeric compound prepared according to the following method which comprises the steps of: (a) providing an isocyanate-functional polymeric compound which has a substantial portion of the isocyanate groups masked by agents that can be removed by heating; (b) adding a crosslinking agent to said masked isocyanate-functional polymeric compound, and allowing said crosslinking agent and said masked isocyanate-functional polymeric compound to react at an elevated temperature for a period of time which is sufficient to unmask no more than about one-third of said masked isocyanate-functional polymer, in order to partially react said crosslinking agent and said unmasked isocyanate-functional polymer; (c) maintaining said reaction at said elevated temperature until a homogeneous solution results.
Claim 7
Dependent Claim
15 words
The retroreflective sheeting of claim 5 wherein said isocyanate-functional compound is an isocyanate-terminated polyurethane compound.
Claim 8
Dependent Claim
16 words
The retroreflective sheeting of claim 6 wherein said masking agent is the isocyanate blocking agent 2-butanoxime.
Claim 9
Dependent Claim
31 words
The retroreflective sheeting of claim 7 wherein said blocking agent is present in a concentration of at least 0.7 equivalents of blocking agent per isocyanate equivalent present in said polymeric compound.
Claim 10
Dependent Claim
15 words
The retroreflective sheeting of claim 5 wherein said isocyanate-functional polymeric compound is an isocyanate-functional acrylic.
Claim 11
Dependent Claim
16 words
The retroreflective sheeting of claim 9 wherein said masking agent is the isocyanate blocking agent 2-butanoxime.
Claim 12
Dependent Claim
28 words
The retroreflective sheeting of claim 5 wherein said isocyanate-functional polymer and said masking agent are incorporated in a cyclic nitrile adduct comprising two or more nitrile functional groups.
Claim 13
Dependent Claim
26 words
The retroreflective sheeting of claim 5 wherein said crosslinking agent is selected from the group consisting of crystalline polyols having three or more active hydrogen groups.
Claim 14
Dependent Claim
24 words
The retroreflective sheeting of claim 12 wherein said crosslinking agent is selected from the group consisting of tris(2-hydroxyethyl)isocyanurate, pentaerythritol, trimethylol propane and trimethylol ethane.
Claim 15
Dependent Claim
35 words
The retroreflective sheeting of claim 12 wherein said crosslinking agent is present in a concentration of 0.8 to 2.0 active hydrogen groups per equivalent of isocyanate group, masked or unmasked, of said isocyanate-functional polymeric compound.
Claim 16
Dependent Claim
26 words
The retroreflective sheeting of claim 5 wherein said crosslinking agent is selected from the group consisting of polyhydroxy-functional polyesters, acrylates, methacrylates, polyvinylbutyrals, polyvinylformals, polythiols and polyamines.
Claim 17
Dependent Claim
20 words
The retroreflective sheeting of claim 5 wherein said crosslinking agent comprises said masked isocyanate-functional polymeric compound and an isocyanate-trimerization catalyst.
Claim 18
Dependent Claim
29 words
The retroreflective sheeting of claim 5 wherein said sheeting further comprises a spacing layer of transparent binder material placed between said transparent microspheres and said underlying specularly reflective layer.
Claim 19
Dependent Claim
18 words
The retroreflective sheeting of claim 17 wherein said sheeting also comprises a carrier web overlying said polymeric layer.
Claim 20
Dependent Claim
85 words
An article useful as an intermediate in the preparation of retroreflective sheeting comprising a monlayer of microspheres partially embedded in an uncured polymeric layer, wherein said uncured polymeric layer when softened by the application of heat exhibits a rolling ball distance of greater than about 200 cm when measured according to the "Tack Rolling Ball Method," PSTC-6, as described herein, at 23° C. and 50% relative humidity, and when reacted to a substantially infusible and insoluble state said polymeric layer comprising urethane or urea linkages.
Claim 21
Dependent Claim
85 words
An article useful as an intermediate in the preparation of retroreflective sheeting comprising a monlayer of microspheres partially embedded in an uncured polymeric layer, wherein said uncured polymeric layer when softened by the application of heat exhibits a rolling ball distance of greater than about 200 cm when measured according to the "Tack Rolling Ball Method," PSTC-6, as described herein, at 23° C. and 50% relative humidity, and when reacted to a substantially infusible and insoluble state said polymeric layer comprising urethane or urea linkages.
Claim 22
Dependent Claim
74 words
The article of claim 19 wherein said uncured polymeric layer comprises (a) a polymeric compound which has isocyanate groups incorporated therein, a substantial portion of said isocyanate groups being masked by agents which may be removed by heating; and (b) a crosslinking agent for said isocyanate groups or a catalyst which provides said isocyanate groups with the ability to crosslink when said polymeric layer is thermally cured to a substantially infusible and insoluble state.
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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) | 1991-02-15 | 1991-08-17 | 1992-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-15 | 1995-08-17 | 1996-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-15 | 1999-08-17 | 2000-02-16 | $7700.00 | Window Closed / Lapsed |