Retroreflective security laminates with protective cover sheets

Claim 1

A legend-containing, substantially transparent laminate which is retroreflective over substantially its entire surface area, said laminate having retroreflective legend areas and retroreflective background areas, which areas are substantially transparent and substantially indistinguishable under ordinary diffuse light viewing conditions, said legend areas and said background areas having visually distinguishable retroreflective properties whereby said legend areas are readily discernible from said background areas under retroreflective light viewing conditions, characterized in that said laminate comprises: a) a base sheet comprising microspheres arranged in substantially a monolayer with partially-light-­transmissive reflectors disposed behind the rear surfaces thereof, said microspheres being at least partially embedded in a transparent binder layer, said base sheet further comprising lacquer disposed behind the rear surfaces of some of said microspheres; and b) a cover sheet bonded to the front side of said base sheet, said cover sheet comprising an outer layer having an abrasion-resistant outer surface and a support layer on the inner surface of said outer layer, said support layer being resistant to deformation under localized pressure and characterized in that it has a thickness of at least about 25 microns and has at least one of the following: 1) a Young's Modulus of between about 2000 and about 6000 MPa or 2) a Knoop Hardness of at least about 10.

Claim 11

A method for making a retroreflective security laminate, said method characterized in that it comprises: a) coating a slurry containing microspheres and binder material onto a temporary carrier such that said microspheres are arranged in substantially a monolayer, said binder material forming a binder layer which comprises a substantially transparent spacing layer upon curing, said carrier adapted such that said binder layer will separate therefrom; b) applying lacquer onto said spacing layer in imagewise fashion; c) forming a dielectric reflector over said lacquer and the exposed portions of said spacing layer; d) applying an attachment adhesive to the back side of said reflector; to yield a base sheet, and e) stripping said base sheet from said carrier; and f) bonding a cover sheet to the front surface of said base sheet, said cover sheet comprising an outer layer having an abrasion-resistant outer surface and a support layer on the inner surface of said outer layer, said support layer being resistant to deformation under localized pressure and characterized in that it has a thickness of at least about 25 microns and has at least one of the following: 1) a Young's Modulus of between about 2000 and about 6000 MPa or 2) a Knoop Hardness of at least about 10.

Claim 12

A method for making a retroreflective security laminate, said method characterized in that it comprises: a) coating a slurry containing microspheres and binder material onto a temporary carrier such that said microspheres are arranged in substantially a monolayer, said binder material forming a binder layer which comprises a substantially transparent spacing layer upon curing, said carrier adapted such that said binder layer will separate therefrom; b) applying lacquer onto said spacing layer in imagewise fashion; c) forming a dielectric reflector over said lacquer and the exposed portions of said spacing layer; d) applying an attachment adhesive to the back side of said reflector; to yield a base sheet, and e) stripping said base sheet from said carrier; and f) bonding a cover sheet to the front surface of said base sheet, said cover sheet comprising an outer layer having an abrasion-resistant outer surface and a support layer on the inner surface of said outer layer, said support layer being resistant to deformation under localized pressure and characterized in that it has a thickness of at least about 25 microns and has at least one of the following: 1) a Young's Modulus of between about 2000 and about 6000 MPa or 2) a Knoop Hardness of at least about 10.

Claim 14

A method for making a retroreflective security laminate characterized in that said method comprises: a) providing a cover sheet comprising an outer layer having an abrasion-resistant outer surface and an inner surface, a support layer bonded to said inner surface, said support layer being resistant to deformation under localized pressure and characterized in that it has a thickness of at least about 25 microns and has at least one of the following: 1) a Young's Modulus of between about 2000 and about 6000 MPa or 2) a Knoop Hardness of at least about 10 and an optional bonding layer in contact with said support layer on the opposite side of said support layer from said outer layer; b) applying a liquid binder composition onto said cover sheet, said binder composition being such as to yield a binder layer; c) cascading a plurality of microspheres into said binder composition such that said microspheres are arranged in substantially a monolayer and partially embedded in said binder composition; d) forming a binder layer from said binder composition, said microspheres having an index of refraction that is about 1.5 to about 2.0 times that of the index of refraction of said binder layer; e) applying a lacquer in an imagewise fashion onto the exposed surfaces of selected microspheres and said binder layer; f) forming a dielectric reflector over said lacquer and the exposed surfaces of unselected microspheres; g) applying an attachment adhesive to the rear surface of said dielectric reflector.

Claim 15

A method for making a retroreflective security laminate characterized in that said method comprises: a) providing a cover sheet comprising an outer layer having an abrasion-resistant outer surface and an inner surface, a support layer bonded to said inner surface, said support layer being resistant to deformation under localized pressure and characterized in that it has a thickness of at least about 25 microns and has at least one of the following: 1) a Young's Modulus of between about 2000 and about 6000 MPa or 2) a Knoop Hardness of at least about 10 and an optional bonding layer in contact with said support layer on the opposite side of said support layer from said outer layer; b) applying a liquid binder composition onto said cover sheet, said binder composition being such as to yield a binder layer; c) cascading a plurality of microspheres into said binder composition such that said microspheres are arranged in substantially a monolayer and partially embedded in said binder composition; d) forming a binder layer from said binder composition, said microspheres having an index of refraction that is about 1.5 to about 2.0 times that of the index of refraction of said binder layer; e) applying a lacquer in an imagewise fashion onto the exposed surfaces of selected microspheres and said binder layer; f) forming a dielectric reflector over said lacquer and the exposed surfaces of unselected microspheres; g) applying an attachment adhesive to the rear surface of said dielectric reflector.