# US 7,611,251 B2 · Retroreflective articles comprising olefinic seal films > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,611,251 B2 - Document ID: US7611251B2 - Status: Granted - Kind: B2 - Application number: 11/379,130 - Filed: 2006-04-18 - Published: 2007-10-18 - Granted: 2009-11-03 - Earliest claimed: 2006-04-18 - Assignees: 3M Innovative Properties Company - Inventors: Bimal V. Thakkar; Jeffrey O. Emslander; Steven M. Nielsen; Douglas J. Hall; David G. Schueler - Web page: https://patentgrep.com/patent/US7611251B2 ## CPC - G02B 5/124: plural reflecting elements forming part of a unitary plate or sheet - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract Microstructured articles, such as a retroreflective articles, having a plurality of (e.g. cube-corner) microstructured elements and a seal film layer adhered to portions of the cube-corner elements and/or portions of a (e.g. flexible) body layer. The seal film is a thermoplastic polymeric material comprising reaction products of alkylene in an amount of at least about 50% and reaction products of at least one non-acidic polar monomer. ## Claims ### Claim 1 A flexible retroreflective article comprising a polymeric light transmissive body layer having an elastic modulus of less than 7×108 pascals; a plurality of cube-corner elements projecting from a major surface of the body layer; and a multilayered seal film having a first film layer and a second film layer, the second film layer adhered to at least portions of the body layer such that the seal film maintains an air interface with the cube-corner elements; the second film layer comprising a thermoplastic polymeric material comprising reaction products of alkylene in an amount of at least about 50% by weight and reaction products of at least one non-acidic polar monomer wherein the thermoplastic material has a different melt flow index than the seal film layer in contact with the body layer; wherein the seal film layer in contact with the body layer is a thermoplastic polymeric material comprising reaction products of alkylene in an amount of at least about 50% by weight and reaction products of at least one non-acidic polar monomer and the thermoplastic polymeric material comprises acid modification, anhydride modification, carbon monoxide modification, or a combination thereof. ### Claim 2 (depends on 1) The flexible retroreflective article of claim 1 wherein the alkylene has 2 to 8 carbon atoms. ### Claim 3 (depends on 2) The flexible retroreflective article of claim 2 wherein the alkylene is ethylene. ### Claim 4 (depends on 1) The flexible retroreflective article of claim 1 wherein the non-acidic monomer is selected from vinyl acetate, alkyl(meth)acrylate monomers, and mixtures thereof. ### Claim 5 (depends on 4) The flexible retroreflective article of claim 4 wherein the alkyl(meth)acrylate has an alkyl group having 1 to 8 carbon atoms. ### Claim 6 (depends on 5) The flexible retroreflective article of claim 5 wherein the alkyl (meth)acrylate is selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate and mixtures thereof. ### Claim 7 (depends on 1) The flexible retroreflective article of claim 1 wherein the seal film comprises a copolymer or terpolymer of alkylene and at least one non-acid polar comonomer selected from vinyl acetate; alkyl(meth)acrylate monomers, and mixtures thereof. ### Claim 8 (depends on 7) The flexible retroreflective article of claim 7 wherein the copolymer or terpolymer comprises about 10 wt-% to about 40 wt-% of vinyl acetate, alkyl(meth)acrylate monomers, and mixtures thereof. ### Claim 9 (depends on 1) The flexible retroreflective article of claim 1 wherein the seal film is selected from acid- or anhydride-modified EVA, acid or anhydride-/acrylate-modified EVA, acid- or anhydride-modified ethylene acrylate polymers, and EVA carbon monoxide terpolymers. ### Claim 10 (depends on 1) The flexible retroreflective article of claim 1 wherein the seal film comprises a blend of at least two thermoplastic polymers and the blend comprises reaction products of alkylene in an amount of at least about 50% by weight and reaction products of vinyl acetate, alkyl(meth)acrylate monomers, and mixtures thereof. ### Claim 11 (depends on 10) The flexible retroreflective article of claim 10 wherein the blend comprises a thermoplastic polymer selected from ionomeric ethylene copolymers, low density polyethylene, EAA, EMA, and polyurethanes. ### Claim 12 (depends on 1) The flexible retroreflective article of claim 1 wherein the seal film has a melt index of less than 25 g/10 min as measured according to ASTM D 1238. ### Claim 13 (depends on 1) The flexible retroreflective article of claim 1 wherein the seal film further comprises at least one pigment, dye, or combination thereof. ### Claim 14 (depends on 1) The flexible retroreflective article of claim 1 wherein the seal film is monolithic. ### Claim 15 (depends on 1) The flexible retroreflective article of claim 1 wherein the second film layer comprises the same thermoplastic polymeric material as claim 1 and further comprises 5 wt-% to 30 wt-% of pigment. ### Claim 16 (depends on 1) The flexible retroreflective article of claim 1 wherein the seal film contacts the body layer or cube film at an interface and the interface further comprises an adhesion promoting surface treatment. ### Claim 17 (depends on 16) The flexible retroreflective article of claim 16 wherein the adhesion promoting surface treatment comprises a prime layer, corona treatment, or a combination thereof. ### Claim 18 (depends on 1) The flexible retroreflective article of claim 1 wherein the body layer comprises a polymeric material selected from ionomeric ethylene copolymers, low density polyethylenes, polyethylene copolymers, plasticized poly(vinylchloride), polyurethane, and mixtures thereof. ### Claim 19 (depends on 1) The flexible retroreflective article of claim 1 wherein the body layer is olefinic. ### Claim 20 A retroreflective article that comprises: a plurality of cube-corner elements; and a multilayered seal film layer having a first film layer and a second film layer, the second film layer adhered to portions of the cube-corner elements such that the seal film maintains an air interface with the cube-corner elements, the second film layer comprising a thermoplastic polymeric material comprising reaction products of alkylene in an amount of at least about 50% by weight and reaction products of at least one non-acidic polar monomer wherein the thermoplastic material has a different melt flow index than the seal film layer in contact with the body layer; wherein the seal film layer in contact with the cube-corner elements is a thermoplastic polymeric material comprising reaction products of alkylene in an amount of at least about 50% by weight and reaction products of at least one non-acidic polar monomer and the thermoplastic polymeric material comprises acid modification, anhydride modification, carbon monoxide modification, or a combination thereof. ### Claim 21 (depends on 20) The retroreflective article of claim 20 wherein the cube-corner elements project from an integral body layer. ### Claim 22 (depends on 20) The retroreflective article of claim 20 wherein the cube-corner elements compose a thermoplastic polymeric material. ### Claim 23 (depends on 20) The flexible retroreflective article of claim 20 wherein the cube-corner elements comprise the reaction product of a polymerizable resin composition. ### Claim 24 (depends on 20) The flexible retroreflective article of claim 20 wherein the cube-corner elements comprise at least one nitrogen-containing ingredient. ### Claim 25 A method of making a retroreflective article comprising: providing a light transmissive polymeric body layer comprising a plurality of cube-corner elements projecting from a major surface of the body layer; and thermally bonding a multilayered seal film, having a first film layer and a second film layer, to portions of the body layer or to the cube-corner elements such that the seal film maintains an air interface with the cube-corner elements, the second film layer comprising a thermoplastic polymeric material comprising reaction products of alkylene in an amount of at least about 50% by weight and reaction products of at least one non-acidic polar monomer wherein the thermoplastic material has a different melt flow index than the seal film layer in contact with the body layer; wherein the seal film layer in contact with the body layer or cube-corner elements is a thermoplastic polymeric material comprising reaction products of alkylene in an amount of at least about 50% by weight and reaction products of at least one non-acidic polar monomer and the thermoplastic polymeric material comprises acid modification, anhydride modification, carbon monoxide modification, or a combination thereof. ### Claim 26 A microstructured article that comprises a plurality of polymeric microstructured elements; and a multilayered seal film having a first film layer and a second film layer, the second film layer adhered to portions of the microstructured elements such that the seal film maintains an air interface with the microstructured elements, the second film layer comprising a thermoplastic polymeric material comprising reaction products of alkylene in an amount of at least about 50% by weight and reaction products of at least one non-acidic polar monomer wherein the thermoplastic material has a different melt flow index than the seal film layer in contact with the body layer; wherein the seal film layer in contact with the microstructured elements is a thermoplastic polymeric material comprising reaction products of alkylene in an amount of at least about 50% by weight and reaction products of at least one non-acidic polar monomer and the thermoplastic polymeric material comprises acid modification, anhydride modification, carbon monoxide modification, or a combination thereof. ### Claim 27 (depends on 1) The microstructured article of claim 1 wherein the seal film is bonded in part to the cube-corner elements. ### Claim 28 (depends on 1) The flexible retroreflective article of claim 1 wherein the second film layer comprises a different thermoplastic polymeric material than the seal film layer in contact with the body layer. ### Claim 29 (depends on 28) The flexible retroreflective article of claim 28 further comprising a tie layer between the seal film layer and the second film layer.