US4663213A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transparent multi-layer cover film for retroreflective sheeting
Assignee: 3M Co
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Filing: 1985-11-18
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Granted: 1987-05-05
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Expires: 2005-11-18
Abstract
Abstract Retroreflective sheeting has a flat, transparent cover film of excellent clarity and weatherability that resists dirt accumulation while also having good flexibility, conformability and stretchability, this desirable combination of properties being achieved when the cover film includes a urethane inner layer and an acrylic outer layer. The acrylic outer layer preferably is a copolymer of 60 to 80 parts of methyl methacrylate and correspondingly 40 to 20 parts by weight of at least one of ethyl acrylate, n-butyl acrylate, and-butyl methacrylate. The urethane inner layer comprises a thermoplastic aliphatic urethane polymer.
Inventors
- 👤 Terry R. Bailey
- 👤 Roger R. Kult
- 👤 Louis C. Belisle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:11
CPC Classifications
B; B32; B32B; B32B7/00; B32B7/02; G; G02; G02B; G02B5/00; G02B5/12; G02B5/126; G02B5/128; B32B27/00; B32B27/30; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10T; Y10T428/00; Y10T428/24; Y10T428/24802; Y10T428/24851; Y10T428/24868; Y10T428/24876; Y10T428/24926; Y10T428/25; Y10T428/252; Y10T428/31504; Y10T428/31551; Y10T428/31573
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
63 words
Retroreflective sheeting having a flat, transparent, multi-layer cover film, an outer layer comprising an acrylic copolymer of monomers comprising methyl methacrylate and another acrylate or methacrylate, the alkyl or aralkyl group of which contains up to eight carbon atoms, the methyl methacrylate comprising from 20 to 90 percent by weight of the monomers, and an inner layer comprising a thermoplastic aliphatic urethane polymer.
Claim 2
Dependent Claim
63 words
Retroreflective sheeting having a flat, transparent, multi-layer cover film, an outer layer comprising an acrylic copolymer of monomers comprising methyl methacrylate and another acrylate or methacrylate, the alkyl or aralkyl group of which contains up to eight carbon atoms, the methyl methacrylate comprising from 20 to 90 percent by weight of the monomers, and an inner layer comprising a thermoplastic aliphatic urethane polymer.
Claim 3
Dependent Claim
22 words
Retroreflective sheeting as defined in claim 1 wherein said monomers comprise at least one of ethyl acrylate, n-butyl acrylate, and n-butyl methacrylate.
Claim 4
Dependent Claim
43 words
Retroreflective sheeting as defined in claim 2 wherein the acrylic outer layer is a copolymer of 60 to 80 parts of methyl methacrylate and correspondingly 40 to 20 parts by weight of at least one of ethyl acrylate, n-butyl acrylate, and n-butyl methacrylate.
Claim 5
Dependent Claim
22 words
Retroreflective sheeting as defined in claim 1 wherein the thickness of the inner urethane layer exceeds that of the outer acrylic layer.
Claim 6
Dependent Claim
21 words
Retroreflective sheeting as defined in claim 1 wherein the thickness of the acrylic outer layer is from 5 to 40 micrometers.
Claim 7
Dependent Claim
22 words
Retroreflective sheeting as defined in claim 1 wherein the thickness of the inner urethane layer is not more than about 200 mm.
Claim 8
Dependent Claim
15 words
Retroreflective sheeting as defined in claim 1 wherein the inner and outer layers are coextruded.
Claim 9
Dependent Claim
18 words
Retroreflective sheeting as defined in claim 1 wherein the elongation of the cover film is at least 50%.
Claim 10
Dependent Claim
27 words
Retroreflective sheeting as defined in claim 1 of the enclosed-lens type including a binder layer to which the inner urethane layer is sealed over its full area.
Claim 11
Dependent Claim
48 words
Retroreflective sheeting as defined in claim 1 of the encapsulated-lens type including a binder layer to which the inner urethane layer is sealed along a network of interconnecting lines to form a plurality of hermetically sealed cells within which the microspheres are encapsulated and have an air interface.
Claim 12
Dependent Claim
54 words
Method of making a transparent cover film for retroreflective sheeting comprising coextruding at least two layers, one layer comprising an acrylic copolymer of monomers including methyl methacrylate and another acrylate or methacrylate, the alkyl or aralkyl group of which contains up to eight carbon atoms, and another layer comprising a thermoplastic aliphatic urethane polymer.
Claim 13
Dependent Claim
54 words
Method of making a transparent cover film for retroreflective sheeting comprising coextruding at least two layers, one layer comprising an acrylic copolymer of monomers including methyl methacrylate and another acrylate or methacrylate, the alkyl or aralkyl group of which contains up to eight carbon atoms, and another layer comprising a thermoplastic aliphatic urethane polymer.
Claim 14
Dependent Claim
35 words
Method as defined in claim 11 including a subsequent step of drawing the extruded composite to substantially reduce its thickness to less than 240 micrometers while substantially avoiding orientation of the material of either layer.
Claim 15
Dependent Claim
30 words
Method as defined in claim 12 wherein in said additional step the thickness of the outer acrylic layer is reduced to within the range of from 5 to 40 micrometers.
Claim 16
Dependent Claim
27 words
Method as defined in claim 11 including a subsequent step of bonding the urethane layer of the drawn composite to the top surface of retroreflecting base material.
Claim 17
Dependent Claim
56 words
Method of making a transparent cover film for retroreflective sheeting comprising laminating at an elevated temperature preformed films, one film comprising an acrylic copolymer of monomers including methyl methacrylate and another acrylate or methacrylate, the alkyl or aralkyl group of which contains up to eight carbon atoms, and another film comprising a thermoplastic aliphatic urethane polymer.
Claim 18
Dependent Claim
56 words
Method of making a transparent cover film for retroreflective sheeting comprising laminating at an elevated temperature preformed films, one film comprising an acrylic copolymer of monomers including methyl methacrylate and another acrylate or methacrylate, the alkyl or aralkyl group of which contains up to eight carbon atoms, and another film comprising a thermoplastic aliphatic urethane polymer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-04 | 1990-11-03 | 1991-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-04 | 1994-11-03 | 1995-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-04 | 1998-11-03 | 1999-05-05 | $7700.00 | Window Closed / Lapsed |