# US 10,502,869 B2 · Optical element with a porous low refractive index layer having a protection layer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,869 B2 - Document ID: US10502869B2 - Status: Granted - Kind: B2 - Application number: 13/879,842 - Filed: 2011-10-20 - Published: 2013-08-08 - Granted: 2019-12-10 - Earliest claimed: 2010-10-20 - Assignees: 3M Innovative Properties Company - Applicants: William D. Coggio; Ramesh C. Kumar; John A. Wheatley; Michael L. Steiner; William F. Edmonds; Lan H. Liu; Encai Hao; Robert F. Kamrath; John J. Stradinger - Inventors: William D. Coggio; Ramesh C. Kumar; John A. Wheatley; Michael L. Steiner; William F. Edmonds; Lan H. Liu; Encai Hao; Robert F. Kamrath; John J. Stradinger - Web page: https://patentgrep.com/patent/US10502869B2 ## CPC - G02B 1/105 - G02B 1/14: Protective coatings, e.g. hard coatings - G02B 1/11: Anti-reflection coatings - G02B 2207/107: Porous materials, e.g. for reducing the refractive index - Y10T 428/24975: No layer or component greater than 5 mils thick - Y10T 428/24997: Of metal-containing material - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An optical article includes an optical element, a low refractive index layer disposed on the optical element having an effective refractive index of 1.3 or less and a polymeric protective layer disposed on the low refractive index layer. The low refractive index layer includes a binder, a plurality of metal oxide particles dispersed in the binder, and a plurality of interconnected voids. The polymeric protective layer does not increase an effective refractive index of the optical article by greater than 10%. ## Claims ### Claim 1 An optical article comprising: a first optical element comprising a polarizing film, a diffusing film, a reflecting film, a retarder, a light guide or a liquid crystal display panel; and a second optical element comprising: (a) a low refractive index layer having an effective refractive index of 1.3 or less disposed on the first optical element, the low refractive index layer comprising: a binder; a plurality of particles of fumed silica or fumed alumina dispersed in the binder; wherein the low refractive index layer comprises a plurality of interconnected voids and has a thickness of 1 to 20 micrometers; and (b) a water resistant polymeric protective layer formed from polymers having an average molecular weight of greater than 50,000 g/mol disposed on the low refractive index layer, wherein the polymeric protective layer has a thickness of 1 to 15 micrometers, said polymers comprising: organomodified silicones selected from the group consisting of (meth)acrylate modified silicones, silicone modified (meth)acrylates, silicone-polyureas, silicone-polyurethane-polyureas, silicone polyamides, and silicone polyoxamides; or thermoplastic silicone acrylate copolymers; and wherein the polymeric protective layer does not increase an effective refractive index of the second optical element by greater than 10% as compared to a second optical element having no polymeric protective layer. ### Claim 2 (depends on 1) An optical article according to claim 1, wherein the polymeric protective layer is formed from polymers having an average molecular weight of at least 100,000 g/mol. ### Claim 3 (depends on 1) An optical article according to claim 1, wherein the polymeric protective layer comprises cross-linked polymers. ### Claim 4 (depends on 3) An optical article according to claim 3, wherein the polymeric protective layer is formed from an aqueous emulsion. ### Claim 5 (depends on 1) An optical article according to claim 1, wherein the polymeric protective layer comprises thermoplastic polymers having a Tg of 60 degrees centigrade or greater. ### Claim 6 (depends on 1) An optical article according to claim 1, wherein the polymeric protective layer is a pressure sensitive adhesive. ### Claim 7 (depends on 1) An optical article according to claim 1, wherein the polymeric protective layer comprises a plurality of haze generating particles dispersed in the protective layer. ### Claim 8 (depends on 7) An optical article according to claim 7, wherein the haze generating particles have an average lateral dimension of 1 micrometer or greater. ### Claim 9 (depends on 1) An optical article according to claim 1, wherein the plurality of particles comprises fumed silica. ### Claim 10 (depends on 1) An optical article according to claim 1, wherein a weight ratio of the binder to the plurality of particles is 1:2 or less. ### Claim 11 (depends on 1) An optical article according to claim 1, wherein the optical article has a haze value of at least 75%. ### Claim 12 (depends on 1) An optical article according to claim 1, further comprising a second low refractive index layer disposed on the optical element or polymeric protective layer or between the low refractive index layer and the polymeric protective layer. ### Claim 13 An optical article comprising: an optical element; a low refractive index layer having an effective refractive index of 1.3 or less disposed on the optical element, the low refractive index layer comprising: a binder; a plurality of fumed silica particles dispersed in the binder; and wherein the low refractive index layer comprises a plurality of interconnected voids and has a thickness of 1 to 20 micrometers; and a polymeric protective layer formed from polymers having an average molecular weight of greater than 50,000 g/mol said polymers comprising crosslinked organo-modified silicone selected from the group consisting of (meth)acrylate modified silicones, silicone modified (meth)acrylates, silicone-polyureas, silicone-polyurethane-polyureas, silicone polyamides, and silicone polyoxamides; wherein the polymeric protective layer has a thickness of 1 to 15 micrometers. ### Claim 14 (depends on 13) An optical article according to claim 13, wherein the polymeric protective layer comprises polymers having an average molecular weight of at least 100,000 g/mol. ### Claim 15 (depends on 13) An optical article according to claim 13, wherein the polymeric protective layer comprises polymers having an average molecular weight of at least 250,000 g/mol. ### Claim 16 (depends on 13) An optical article according to claim 13, wherein the polymeric protective layer comprises polymers having an average molecular weight of at least 500,000 g/mol. ### Claim 17 (depends on 13) An optical article according to claim 13, wherein a weight ratio of the binder to the plurality of particles is 1:2 or less. ### Claim 18 (depends on 13) An optical article according to claim 13, wherein the optical article has a haze value of at least 75%.