# US 11,898,023 B2 · Polyolefin photovoltaic backsheet comprising a stabilized polypropylene layer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,898,023 B2 - Document ID: US11898023B2 - Status: Granted - Kind: B2 - Application number: 17/130,920 - Filed: 2020-12-22 - Published: 2021-04-22 - Granted: 2024-02-13 - Earliest claimed: 2014-06-24 - Assignees: Dow Global Technologies LLC - Applicants: Dow Global Technologies LLC - Inventors: Jeffrey E. Bonekamp; Huiqing Zhang; Fanny Deplace - Web page: https://patentgrep.com/patent/US11898023B2 ## CPC - C08K 5/3435: Piperidines - C08K 5/005: {Stabilisers against oxidation, heat, light, ozone} - C08K 5/101: of monocarboxylic acids - C08K 5/3432: Six-membered rings - C08K 5/3462: Six-membered rings - C08K 5/3472: Five-membered rings - C08K 5/3492: Triazines - C08K 5/36: Sulfur-, selenium-, or tellurium-containing compounds {(C08K5/0091 takes precedence)} - C08K 5/372: Sulfides {, e.g. R-(S)x-R'} - C08L 23/0815: {with aliphatic 1-olefins containing one carbon-to-carbon double bond} - C08L 23/10: Homopolymers or copolymers of propene - C08L 23/16: Ethylene-propylene or ethylene-propylene-diene copolymers - C08L 51/06: grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond - H10F 19/804: {Materials of encapsulations} - H10F 19/85: Protective back sheets - C08J 2323/10: Homopolymers or copolymers of propene - C08L 2205/025: containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure - Y02E 10/50: Photovoltaic [PV] energy - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract Polyolefin photovoltaic (PV) backsheets comprise a polypropylene layer stabilized with (A) at least one hindered amine with 2,2,6,6-tetraalkylpiperdine or 2,2,6,6 -tetraakylpiperazinone, either or both in combination with a triazine moiety, (B) a thioester, and, optionally, (C) at least one hindered hydroxybenzoate, and/or (D) an ortho hydroxyl triazine compound. These PV backsheets exhibit a low flame spread index of <100 without the use of FR agents, and the polypropylene layer exhibits good weatherability while providing the required long term heat aging performance necessary for PV modules. ## Claims ### Claim 1 A polyolefin photovoltaic (PV) backsheet comprising: an optional seal layer (A); an optional tie layer (B); and a layer (C) composed of a first polypropylene and a second polypropylene different than the first polypropylene, the first polypropylene and the second polypropylene each having a melting point greater than 125° C.; the layer (C) stabilized with (A) from 0.5 wt % to 3.0 wt % of at least one hindered amine comprising a radical selected from the group consisting of a 2,2,6,6-tetraalkylpiperidine having a triazine moiety, a 2,2,6,6-tetraakylpiperazinone radical having a triazine moiety, and combinations thereof, (B) from 3,000 ppm to 6,000 ppm of a thioester, (C) from 7,500 ppm to 15,000 ppm of at least one hindered hydroxybenzoate that is 3 5-di-tert-butyl-4-hydroxybenzoic acid, hexadecyl ester, and (D) from 100 ppm to 4,000 ppm of an ortho hydroxyl triazine compound, wherein weight percent of (A), (B), (C), and (D) is based on total weight of the layer (C); and the layer (C) is void of flame retardant agents and has a flame spread index less than 100 as measured in accordance with ASTM E162-02a. ### Claim 2 (depends on 1) The PV backsheet of claim 1 wherein the first polypropylene and the second polypropylene each have a heat fusion of at least 60 J/g. ### Claim 3 (depends on 2) The PV backsheet of claim 2 further comprising a third polypropylene different than the first polypropylene and different than the second polypropylene, the third polypropylene having a melting point greater than 125° C. ### Claim 4 (depends on 1) The PV backsheet of claim 1 wherein the layer (C) further comprises a polyolefin other than polypropylene. ### Claim 5 (depends on 4) The PV backsheet of claim 4 wherein total amount of the first polypropylene and the second polypropylene is 55 to 77.2 wt % based on total weight of the layer (C). ### Claim 6 (depends on 5) The PV backsheet of claim 5 wherein the polyolefin is selected from the group consisting of linear low density polyethylene and plastomer. ### Claim 7 (depends on 5) The PV backsheet of claim 5 wherein the layer (C) comprises a first polyolefin and a second polyolefin, each polyolefin different than polypropylene and the second polyolefin different than the first polyolefin. ### Claim 8 (depends on 7) The PV backsheet of claim 7 wherein the first polyolefin is a linear low density polyethylene and the second polyolefin is a plastomer. ### Claim 9 (depends on 1) The PV backsheet of claim 1 wherein the PV backsheet is a monolayer film consisting of layer (C), the monolayer film having a thickness from 100 microns to 375 microns. ### Claim 10 (depends on 1) The PV backsheet of claim 1 wherein the triazine moiety is oligomeric, polymeric or has a weight average molecular weight (Mw) of at least 500. ### Claim 11 (depends on 10) The PV backsheet of claim 10 wherein the layer (C) further comprises at least one of an acid scavenger, metal deactivator, primary antioxidant, and a secondary antioxidant. ### Claim 12 (depends on 1) The PV backsheet of claim 1 wherein a weight ratio of (C) the at least one hindered hydroxybenzoate to (A) the at least one hindered amine is from 0.25:1 to 3:1. ### Claim 13 (depends on 1) The PV backsheet of claim 1 wherein the tie layer (B) is present and the tie layer (B) contains a component selected from the group consisting of ethylene-glycidyl (meth)acrylate and crystalline block copolymer. ### Claim 14 (depends on 13) The PV backsheet of claim 13 wherein the tie layer contains the crystalline block copolymer and the crystalline block copolymer comprises (i) a crystalline ethylene-based polymer (CEP); (ii) a propylene-based crystalline polymer (CPP); and (iii) a block copolymer comprising (A) an ethylene polymer block (EB) that is a crystalline ethylene block; and (B) a crystalline propylene polymer block (CPPB). ### Claim 15 (depends on 13) The PV backsheet of claim 13 wherein the seal layer (A) is present. ### Claim 16 (depends on 1) The PV backsheet of claim 1 wherein the seal layer (A) is present and the tie layer (B) is present. ### Claim 17 (depends on 16) The PV backsheet of claim 16 wherein the seal layer comprises an ethylene-based polymer. ### Claim 18 (depends on 17) The PV backsheet of claim 17 wherein the tie layer (B) contains a component selected from the group consisting of ethylene-glycidyl (meth)acrylate and crystalline block copolymer. ### Claim 19 (depends on 18) The PV backsheet of claim 18 wherein the tie layer (B) contains the crystalline block copolymer and the crystalline block copolymer comprises (i) a crystalline ethylene-based polymer (CEP); (ii) a propylene-based crystalline polymer (CPP); and (iii) a block copolymer comprising (A) an ethylene polymer block (EB) that is a crystalline ethylene block; and (B) a crystalline propylene polymer block (CPPB).