WO2021191757A1 - Procédé de stratification amélioré - Google Patents

Procédé de stratification amélioré Download PDF

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Publication number
WO2021191757A1
WO2021191757A1 PCT/IB2021/052318 IB2021052318W WO2021191757A1 WO 2021191757 A1 WO2021191757 A1 WO 2021191757A1 IB 2021052318 W IB2021052318 W IB 2021052318W WO 2021191757 A1 WO2021191757 A1 WO 2021191757A1
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WO
WIPO (PCT)
Prior art keywords
adhesive
substrate
multilayer stack
backsheet
light management
Prior art date
Application number
PCT/IB2021/052318
Other languages
English (en)
Inventor
Jiaying Ma
Herve E. Deve
Thomas K. ELLINGHAM, Jr.
Jay M. Jennen
Scott R. Meyer
Christopher M. SCHENIAN
Original Assignee
3M Innovative Properties Company
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Publication date
Application filed by 3M Innovative Properties Company filed Critical 3M Innovative Properties Company
Publication of WO2021191757A1 publication Critical patent/WO2021191757A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/1055—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer
    • B32B17/10678—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer comprising UV absorbers or stabilizers, e.g. antioxidants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/1055—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer
    • B32B17/10697—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer being cross-linked
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/1055—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer
    • B32B17/10788—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer containing ethylene vinylacetate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10807—Making laminated safety glass or glazing; Apparatus therefor
    • B32B17/10816—Making laminated safety glass or glazing; Apparatus therefor by pressing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10807—Making laminated safety glass or glazing; Apparatus therefor
    • B32B17/10972—Degassing during the lamination
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/0007—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding involving treatment or provisions in order to avoid deformation or air inclusion, e.g. to improve surface quality
    • B32B37/003—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding involving treatment or provisions in order to avoid deformation or air inclusion, e.g. to improve surface quality to avoid air inclusion
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/048—Encapsulation of modules
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/054—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means
    • H01L31/0547—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means comprising light concentrating means of the reflecting type, e.g. parabolic mirrors, concentrators using total internal reflection
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/12—Photovoltaic modules
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/52—PV systems with concentrators

Definitions

  • the present invention is directed to an improved lamination process.
  • a method of applying an adhesive to a substrate to mitigate entrapment of air bubbles during a vacuum lamination of a multilayer stack is described.
  • PV photovoltaic
  • solar cells also referred to as solar cells
  • PV cells are relatively small in size and are typically combined into a physically integrated PV module (or solar module) having a correspondingly greater power output than the individual PV cells of the module.
  • PV modules are generally formed from a multilayer stack comprising two or more “strings” of PV cells surrounded by an encapsulant and enclosed by front and back panels, wherein at least one panel is transparent to sunlight.
  • the multilayer stack is laminated together to form the PV module which provides mechanical support for the individual PV cells and protects them against damage due to environmental factors such as wind, snow, and ice.
  • the PV module is typically fitted into a metal frame, with a sealant covering the edges of the module engaged by the metal frame.
  • the metal frame protects the edges of the module, provides additional mechanical strength, and facilitates combining it with other modules so as to form a larger array or solar panel that can be mounted to a suitable support.
  • the total active surface area of the array i.e., the front faces of the PV cells
  • the PV cells are arranged in the PV module with space between the adjacent PV cells and between the PV cells and the edge of the module.
  • This arrangement reduces the efficiency of the solar cell since some of the sunlight impinging on the PV modules falls on the inactive areas that lie between the PV cells or border the entire array of cells in the module.
  • the efficiency of the solar cell can be increased by providing a reflective light management material in the inactive areas of the PV module to reflect the sunlight impinging on these areas onto the face of the PV cells.
  • These reflective light management materials can include an adhesive layer to facilitate positioning of the reflective light management materials prior to lamination.
  • Difficulties can arise during lamination of large articles such as PV modules, especially if some of the layers in the multilayer stack have complex or intermittent structures.
  • the intermittent structures may act as dams that can prevent removal of entrapped air from the multilayer stack.
  • air can become entrapped within the layers of the PV module due to relative viscosity differences between the flowable materials, such as the encapsulants, adhesives, etc. used to create the PV module.
  • the entrapped air can decrease interlayer and/or intralayer adhesion and create aesthetic issues.
  • An improved lamination process is provided herein.
  • a method of applying an adhesive to a substrate to mitigate entrapment of air bubbles during a vacuum lamination process comprises contacting the adhesive to a surface of the substrate and applying a periodic force to the adhesive along the longitudinal direction creating first regions having a first adhesion strength to the substrate and second regions having a second adhesion strength to the substrate, wherein the second adhesion strength is less than 90% of the first adhesion strength.
  • a laminated article can be formed by first creating a multilayer stack of the constituent layers, wherein the layers include a first substrate, a discontinuous structure comprising a member having an adhesive layer disposed on the member, and a flowable material layer.
  • the discontinuous member can be attached to a surface of the substrate by first contacting the adhesive of the discontinuous member to a surface of the substrate and applying pressure to periodically tack down the adhesive layer of the discontinuous member onto the surface of the substrate.
  • a flowable film layer can be laid on the substrate over the discontinuous member.
  • the multilayer stack can be placed in a vacuum laminator and laminated to create a laminated article.
  • an exemplary method of forming a PV modules comprises creating a multilayer stack that includes a backsheet; a light management material, wherein the light management material comprises flexible light redirecting film having a plurality of microstructures extending from a first surface of the film and a continuous adhesive layer disposed on a second surface of the film; an array of PV cells; at least one layer of a flowable encapsulant and a front sheet.
  • the light management material is applied to the backsheet using pressure to periodically tack down the adhesive layer of the light management material onto the surface of the backsheet.
  • a first encapsulant film is placed on the backsheet over the light management material and an array of interconnected PV cells is placed on top of the first encapsulant sheet.
  • a second film encapsulant sheet is placed over the array of interconnected PV cells and a front sheet is placed on top of the second encapsulant sheet.
  • the multilayer stack is heated to a temperature above the melt temperature of the first and second encapsulant sheets and a vacuum is applied to remove entrapped air from the multilayer stack. Finally, a laminating pressure is applied to press the layers of the multilayer stack together completing the PV module lamination process.
  • Fig. 1 A shows a schematic cross-section of an exemplary PV module after lamination.
  • Fig. IB is an exploded view of the multilayer stack used to form the PV module of Fig. 1A.
  • Figs. 2A-2C are schematic diagrams illustrating the mechanism of air bubble entrapment in an adhesive layer during vacuum lamination of a multilayer stack.
  • Fig. 3 shows air bubbles that became trapped in an adhesive layer during vacuum lamination of a multilayer stack.
  • Fig. 4 illustrate an exemplary new variable pressure bonding method in accordance with the present invention.
  • Fig. 5 A and 5B show a portion of the pseudo PV module of example Clp before and after lamination.
  • Fig. 6 A and 6B show a portion of the pseudo PV module of example Exlp before and after lamination.
  • Fig. 1A shows a schematic cross-section of an exemplary PV module 100 after lamination and Fig. IB is an exploded view of the multilayer stack used to form the PV module of Fig. 1 A.
  • PV module 100 includes an array of spaced apart PV cells 110 arranged along a length direction and a width direction, an encapsulant material 120 surrounding the PV cells, and top and bottom substrates 130, 140.
  • Tabbing ribbons (not shown) make electrical connections between the PV cells and are generally aligned along the length direction. Areas, such as areas around the perimeter of the module and between the PV cells 110 are photovoltaically inactive.
  • PV cell format can be employed in the PV modules of the present disclosure (e.g., thin film photovoltaic cells, CuInSe2 cells, a-Si cells, e-Si sells, and organic photovoltaic devices, among others).
  • a metallization pattern is applied to the PV cells 110, most commonly by screen-printing of silver inks. This pattern consists of an array of fine parallel gridlines, also known as fingers (not shown). Electrical connectors or tabbing ribbons (not shown) are disposed over and typically soldered to the PV cells to collect current from the fingers.
  • the top or front side substrate 130 serves as a protective cover and is typically made of clear glass or a suitable plastic material that is transparent to solar radiation and the bottom or rear side substrate 140 serves as a support for the PV cells and can be made of the same or a different material as the top substrate.
  • Exemplary encapsulant materials 120 is disposed between the first and second substrates 130, 140 filling any gaps and encasing PV cells 110.
  • the encapsulant material comprises a suitable light-transparent, electrically non-conducting material having an optical transmissivity of at least 50% or at least 80% averaged over the solar spectrum, e.g. from 380 to 1100 nm.
  • Some exemplary encapsulants include curable thermosets, thermosettable fluoropolymers, acrylics, ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), polyolefins, thermoplastic urethanes, clear polyvinylchloride, and ionomers.
  • One exemplary commercially available polyolefin encapsulant is available under the trade designation P08500TM from 3M Company (St. Paul, Minn.). Both thermoplastic and thermoset polyolefin encapsulants can be used.
  • Exemplary polyolefin encapsulant materials are described in United States Patent Nos. 9,276,151 and 9,379,263, incorporated herein by reference in its entirety.
  • Encapsulant material 120 can be provided as discrete sheets that are positioned below and/or on top of the array of PV cells 110, with those components in turn being sandwiched between the first and second substrates 130, 140. Subsequently, the laminate construction is heated under vacuum, causing the encapsulant sheets to become liquefied enough to flow around and encapsulate the PV cells, while simultaneously filling voids in the space between the first and second substrates 130, 140. Upon cooling, the liquefied encapsulant solidifies. In some embodiments, the encapsulant material may additionally be cured in situ to form a transparent solid matrix. The encapsulant material adheres to first and second substrates 130, 140 to form a laminated PV module 100.
  • Strips of light management material 160 can be disposed in inactive areas 150 to redirect light toward the photovoltaically active PV cells 110.
  • Light management material 160 can comprise a light redirecting film (LRF) such as are available from 3M Company (St. Paul, MN).
  • LRF includes a first layer 162 comprising a plurality of microstructures 163 that extend away from a plane of the film.
  • a second layer 165 is disposed on and conforms to surface 163a of the microstructures of the first layer.
  • Second layer 165 is configured to redirect sunlight impinging on the first layer.
  • a third layer comprising an adhesive 170 is disposed on the film layer opposite the microstructures.
  • the LRF may include an optional protective layer 169 disposed over the second layer.
  • first layer 162 can comprise a base layer 164 and a microstructure layer 163.
  • the base layer can be made from polymeric material such as cellulose acetate butyrate; cellulose acetate propionate; cellulose triacetate; poly(meth)acrylates such as polymethyl methacrylate; polyesters such as polyethylene terephthalate and polyethylene naphthalate; copolymers or blends based on naphthalene dicarboxylic acids; polyether sulfones; polyurethanes; polycarbonates; polyvinyl chloride; syndiotactic polystyrene; cyclic olefin copolymers; silicone-based materials; and polyolefins including polyethylene and polypropylene; and blends thereof.
  • the film layer 162 can be formed of a single material.
  • the microstructures/microstmcture layer 163 can have a generally triangular cross sectional shape.
  • the microstructures can have a substantially triangular prism shape, which refers to a prism shape having a cross-sectional area that is 90% to 110% of the area of largest inscribed triangle in the corresponding cross-sectional area of the prism.
  • the substantially triangular prism shape may have slightly rounded facets or a rounded peak.
  • the triangular prisms may be symmetrical (having substantially equal facet lengths and facet angles) or may be asymmetrical (having unequal facet lengths and facet angles).
  • the arrangement of the microstructures can be continuous or discontinuous and can include a repeating pattern, a non-repeating pattern, a random pattern, etc.
  • the second layer of the LRF is made of a reflective material appropriate for reflecting at least some of the sunlight that impinges on the reflective surface of the toward the air-module interface at an angle such that the reflected light undergoes total internal reflection and is reflected again towards the surface of PV cells 110 for absorption.
  • exemplary reflective materials can comprise metallic, inorganic materials or organic materials.
  • the second layer comprises a mirror coating.
  • Exemplary light directing films are described in United States Patent No. 10,205,041, United States Patent Publication No. 2019-0237603, and Patent Cooperation Treaty Application Nos. PCT/IB2019/060127 and PCT/IB2020/061704, each of which is incorporated herein by reference in their entirety.
  • the adhesive layer (i.e. the third layer 170) may be a thermoset or thermoplastic adhesive that is substantially transmissive to the sunlight, e.g., the adhesive layer can have a transmissivity of at least 50% or at least 80% for wavelengths between 380 nm and 1100 nm.
  • the third layer 170 may have a melt flow index of between about 0.1 and 8 g/10 minutes, between about 0.1 and 10 g/10 minutes, between about 0.1 g/10 minutes and 20 g/20 minutes or between 0.1 and 30 g/10 minutes as measured using ASTM D1238 performed at 190°C with a 2.16 kg weight.
  • the adhesive may be of an analogous chemistry to the encapsulant or it may be a different material.
  • the adhesive layer comprises a thermally activatable adhesive, such as a hot melt adhesive and/or a thermally activated cross-linkable adhesive.
  • the adhesive layer may comprise one or more of polyethylene (PE), polypropylene (PP), polyolefin (PO), ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), a polymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV), ethylene tetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF), polyurethane (PU), poly(methyl methacrylate) (PMMA), polyimide (PI), among other materials.
  • PE polyethylene
  • PP polypropylene
  • PO polyolefin
  • EVA ethylene vinyl acetate
  • PVB polyvinyl butyral
  • the adhesive material employed in the third layer 170 may be a polymer that cures through heat, a chemical reaction (e.g., two-part epoxy), and/or irradiation by electron beam or UV radiation, for example. When cured, the third layer material is transformed to a plastic or rubber by crosslinking, forming bonds between individual chains of the polymer.
  • a chemical reaction e.g., two-part epoxy
  • the third layer material is transformed to a plastic or rubber by crosslinking, forming bonds between individual chains of the polymer.
  • Polyethylene resin, ethyl vinyl acetate (EVA), polyurethane, acrylate, and two part silicones are examples of suitable adhesive materials for third layer 170.
  • the adhesive material employed in the third layer 170 may be a polymer that cures through heat, a chemical reaction (e.g., two part epoxy), and/or irradiation by electron beam or UV radiation, for example.
  • the adhesive material in third layer 170 is thermally cured.
  • the third layer material is transformed to a plastic or rubber by crosslinking, forming bonds between individual chains of the polymer.
  • Polyethylene resin, ethyl vinyl acetate (EVA), polyurethane, acrylate, and two part silicones are examples of suitable materials for third layer 170.
  • the adhesive material can be a crosslinkable EVA adhesive comprising a thermal crosslinking agent such as an organic peroxide, a C-radical donor or azo compounds to facilitate thermal crosslinking of the EVA adhesive.
  • a thermal crosslinking agent such as an organic peroxide, a C-radical donor or azo compounds to facilitate thermal crosslinking of the EVA adhesive.
  • Some exemplary peroxides include, for example, diacyl peroxides (such as, for example, dilauryl peroxide and didecanoyl peroxide), alkyl peresters (such as, for example, tert-butyl peroxy-2-ethylhexanoate), perketals (such as, for example, l,l-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane or l,l-di(tert- butylperoxy)cyclohexane), dialkyl peroxides (such as, for example,
  • the adhesive material may optionally include a cross-linking agent to increase the degree of crosslinking in the adhesive.
  • the cross-linking agent can be an allyl group-containing compound, a compound containing acryloxy group, methacryloxy group-containing compound.
  • exemplary allyl group-containing compounds include, for example, allyl isocyanurates, allyl phthalates, allyl fumarates, allyl maleates and the like.
  • a compound containing acryloxy group, methacryloxy group-containing compound, acrylic acid derivatives or methacrylic acid derivative, for example, the ester can be used.
  • ethylene glycol, triethylene glycol, polyethylene glycol esters of poly functional alcohols and the like can be used as well.
  • These cross-linking auxiliary agents can be used in up to 10 parts by weight per 100 parts EVA.
  • the adhesive material may also include one or more adhesion promoters.
  • organosilanes such as chloropropyl silanes, vinyltrichlorosilanes, vinyltriethoxysilanes, vinyl tris(methoxyethoxy)silanes, methacryloxypropyltrimethoxysilanes, (3, 4-ethoxy cyclohexyl) ethyltrimethoxysilanes, glycidoxypropyltrimethoxysilanes, vinyltriacetoxysilanes, mercaptopropyltrimethoxysilanes, aminopropyltriethoxysilanes and aminopropyltrimethoxysilanes can be used in up to 5 parts by weight or less per 100 parts EVA.
  • UV absorbers can be selected to have a “UV cutoff’ of 310, 350, and 380 nm, respectively.
  • HALS are light stabilizers rather than absorbers that scavenge radicals by production of nitroxyl radicals, including, for example, cyclic amines, secondary, tertiary, acetylated, N-hydrocarbyloxy substituted, hydroxy substituted, N-hydrocarbyloxy substituted, or other substituted cyclic amines which are further characterized by a degree of steric hindrance.
  • Antioxidants can be selected from phenolic compounds, sulfur-based compounds, phosphorus-based compounds, amine-based compounds, hydrazine or the like.
  • the adhesive material can be a crosslinked or partially crosslinked EVA hotmelt adhesive such as is described in United States Patent Publication No. 2018-0013027, incorporated herein by reference in its entirety.
  • Crosslinking can be achieved by any method known in the art, including by the use of actinic radiation (e.g., UV and ebeam). In the case of photo-chemically induced crosslinking, the process can be aided by the use of photo initiators and other known catalysts. In other embodiments, the crosslinking occurs by thermal curing, or by a combination of any of the different cross-linking methods disclosed here and know in the art.
  • PV modules are formed by laminating the multilayer stack described above in order to bond the layers together.
  • the light management material can be applied to the second substrate (i.e. the back sheet) with a curable adhesive material using a smooth, round roller to apply constant pressure to the light management materials and under hot air to promote tackiness in the adhesive.
  • the curable adhesive material is a thermally curable EVA based adhesive.
  • heat can also be applied to the second substrate to promote adhesion of the light management material.
  • the multilayer stack is then placed in a heated vacuum chamber at a temperature above the melting point of the encapsulant and the adhesive material to remove air between the layers.
  • the temperature of the vacuum chamber is typically about 128°C, while the melt temperatures of the encapsulant and adhesive materials are usually about 80°C.
  • the entrapped air is pulled out of the multilayer stack by the vacuum.
  • pressure is applied via a bladder with heat to cure/crosslink the adhesive materials.
  • FIGs. 2A-2C schematically illustrate how the bubbles become entrapped in the adhesive layer during vacuum lamination of the multilayer stack. Specifically, Fig. 2A illustrates bubble formation that occurs due to air that is entrapped in the encapsulant material when the encapsulant material is heated above its melting temperature. Vacuum is then applied to the multilayer stack to pull the entrapped air out of the stack, the air bubbles 180 will move towards the edges of the multilayer stack (see Fig. 2B) as indicated by directional arrows 199, 198.
  • air bubbles 180 While air bubbles in the bulk phase of the encapsulant can escape, air bubbles 180, which move into the adhesive layer 170 attaching the light management material to the substrate as they migrate to the edge of the multilayer stack, can become stuck in the adhesive layer 170 as the adhesive material cures as shown in Fig. 2C.
  • Fig. 3 shows air bubbles that became trapped in an adhesive layer during vacuum lamination of a multilayer stack.
  • the entrapment of the air bubbles in the adhesive layer is undesirable.
  • a smooth round roller is conventionally used to apply constant pressure to the adhesive layer when bonding the light management material to the substrate so that the adhesive layer bonds uniformly.
  • Fig. 4 illustrates an exemplary new variable pressure bonding method to apply light management material 160 to substrate 140 which applies pressure to periodically tack down adhesive prior to lamination. In some cases, heat may also be applied to facilitate bonding.
  • the exemplary method uses a grooved roller or cog 280 to apply a periodic force to the adhesive as it moves in direction 190 to create first regions 168 having a higher adhesion strength than second regions 169, wherein the second adhesion strength is less than 90% of the first adhesion strength.
  • the first and second regions are disposed transverse or across the width of the light management material 160.
  • the second adhesion strength is less than 70% of the first adhesion strength.
  • the second adhesion strength is less than 65% of the first adhesion strength.
  • the overall average peel force is 0.25 N/cm or less, 0.20 N/cm or less or 0.15 N/cm or less.
  • the grooved roller 280 has a generally cylindrical shape having a plurality of parallel grooves/valleys 282 formed in the outer surface of the roller.
  • the grooved roller further comprises ridges/peaks 284 disposed adjacent grooves.
  • the grooves may be linear grooves, wavy grooves, sawtooth grooves, etc.
  • the grooves are formed parallel to the central axis 281 of the grooved roller at regular intervals such that the first and second regions are transverse to the travel direction of the roller when the roller is used to apply light management material 160 to substrate 140.
  • the grooves can be formed such that they are biased relative to the central axis in which case the first and second regions are disposed across the width of the light management at an angle relative to the travel direction of the roller.
  • the grooves can be v-shaped, hyperbolically shaped or u-shaped and the ridges may be peaked or rounded.
  • the first regions 168 can be characterized by a length, L, which is determined by the geometry of the ridges 284 of grooved roller 280.
  • the distance, i, between adjacent first regions defines the second regions 169 and is related to the periodicity of grooves 282.
  • the transitions between the first and second regions can be sharp or smooth.
  • the creation of the low adhesion regions provides a pathway for air bubbles to be pulled through by vacuum in the first stage of the lamination process while the high adhesion regions (i.e. first regions 168) ensure that the discontinuous material stays in place.
  • pressure is applied to the multilayer stack to meld the various layers together while still under vacuum.
  • an exemplary roller can comprise raised posts extending from the surface of the roller wherein the space surrounding the posts will give rise to the low adhesion strength second regions and the tops of the posts will provide the high adhesive strength first regions.
  • the posts can have a circular cross-section, an elliptical cross-section, a circular cross-section, a rectangular cross-section or other polygonal shaped cross-section.
  • a laminated article can be formed by first creating a multilayer stack of the constituent layers, wherein the layers include a first substrate, a discontinuous structure comprising a member having an adhesive layer disposed on the member, and a flowable material layer.
  • the discontinuous member can be attached to a surface of the substrate by first contacting the adhesive of the discontinuous member to a surface of the substrate and applying pressure to periodically to tack down adhesive layer of the discontinuous member onto the surface of the substrate.
  • a flowable film layer can be laid on the substrate over the discontinuous member.
  • the multilayer stack van be placed in a vacuum laminator and laminated to create a laminated article.
  • the multilayer stack is created that includes a backsheet; a light management material, wherein the light management material comprises flexible light redirecting film having a plurality of microstructures extending from a first surface of the film and a continuous adhesive layer disposed on a second surface of the film; an array of PV cells; at least one layer of a flowable encapsulant and a front sheet.
  • the light management material is applied to the backsheet using pressure to periodically tack down adhesive layer of the light management material onto the surface of the backsheet such that the light management material is positioned on the backsheet in the inactive areas of the PV module, e.g. in the gaps between adjacent PV cells and between the PV cells and the edge of the PV module.
  • a first encapsulant film is placed on the backsheet over the light management material and an array of interconnected PV cells is placed on top of the first encapsulant sheet.
  • the method comprises rolling a grooved (weighted) roller(s) to apply the periodic pressure to the adhesive layer.
  • An exemplary grooved roller has a surface having a plurality of alternating ridges and grooves formed in the circumferential surface such that the ridges apply greater pressure to the adhesive than the valleys resulting in a bond line between the light management tape and the backsheet has alternating high adhesive strength regions and low adhesive strength regions.
  • the ridges and valleys are disposed parallel to the central axis of the grooved roller and the roller is applied to the light management material such that the ridges and valleys are disposed transverse to a travel direction of the grooved roller.
  • the low adhesive strength regions serve as air migration pathways to allow entrapped air to escape during the vacuum lamination of the multilayer stack.
  • a second film encapsulant sheet is placed over the array of interconnected PV cells and a front sheet placed on top of the second encapsulant sheet.
  • the multilayer stack is heated to a temperature above the melt temperature of the first and second encapsulant sheets and vacuum is applied to remove entrapped air from the multilayer stack. Finally, a laminating pressure is applied to press the layers of the multilayer stack together completing the PV module lamination process.
  • the adhesive layer of the light management material is cured to yield a bond line between the light management tape and the backsheet having a substantially uniform adhesive strength after the lamination process is complete.
  • a periodic force may be applied using a stamping technique with either a one dimensional or two dimensional textured platen or bonding bar.
  • the two dimensional platen can be of approximately the same size as the workpiece or can be smaller than the workpiece and incrementally placed to cover the desired bonding area.
  • Samples were conditioned at room temperature and 50% relative humidity for at least 1 hour prior to testing. One hour before testing the samples were removed from the controlled humidity environment.
  • the T-peel test was used to quantitatively measure the adhesion of the light management material to the backsheet.
  • the T-peel test was done using a MTS Insight 2 from MTS, available from MTS Systems Corporation (Eden Prairie, MN), equipped with a 25N load cell at 12.0 inch/minute (30.48 centimeter/minute) speed.
  • the end of the light management film was separated from the release liner and carefully clamped in the upper jaw of the tester and the free end of backsheet was clamped into the lower jaws of the tester. .
  • the adhesion strength of the first regions i.e. high adhesion regions
  • the second regions i.e. low adhesion strength regions
  • the values above the specimen mean were averaged to give the adhesion strength of the high adhesion strength regions and the values below the specimen mean were averaged to give the adhesion strength of the low adhesion strength regions. From this analysis it is possible to express the adhesion strength of the second regions as a percentage of the adhesion strength of the first regions.
  • a 1.5 in. x 7 in. piece of PET release liner was placed along the log edge of a 5 in. x 7 in. solar backsheet TCP, available from Lucky Film Company (China), with approximately a 0.75 in. overlap such that the release coated side of release liner is disposed along the top of matte side of backsheet.
  • a piece of 3MTM Polyester Tape 8402 available from 3M Company (St. Paul, MN) was applied to the backside to temporarily hold the release liner and backsheet in the desired configuration.
  • the backsheet with attached release liner was heated for approximately 20-30 seconds at a temperature of 100°C on the bed of an NPC Photovoltaic Module Laminator, Model LM-110 X 160-3, available from NPC Incorporated (Tokyo, Japan) for about 20-30 seconds to remove any curvature.
  • NPC Photovoltaic Module Laminator Model LM-110 X 160-3, available from NPC Incorporated (Tokyo, Japan) for about 20-30 seconds to remove any curvature.
  • a 4 in. segment of light management material such as a light redirecting film available from 3M Company (St. Paul, MN) was applied by first placing one end of the LRF material on the release liner such that it overlapped the release liner by 0.5 in. Thumb pressure was applied to the light management material to tack it in place, making sure to avoid contacting the remaining portion of the light management strip from contacting the backsheet.
  • the LRF was attached to the backsheet according to the process described in Table 1.
  • the backsheet was placed smooth side down on the bed of the laminator which had been preheated to 100°C for about one minute.
  • One piece of the BC81 light redirecting film was placed on the rough upward facing surface of the backsheet such that the LRF was positioned 1 in. from the edge of the back sheet and 0.5 in. from the side of the back sheet perpendicular to the edge.
  • the LRF was pressed down onto the backsheet with thumb pressure for about 5 seconds to tack down the end.
  • the applicator as indicated in Table 2, was rolled along the length of the LRF taking about 5 seconds to traverse the length.
  • the remaining piece of LRF were placed down in a similar fashion at a spacing of 1.5 in. away from the previously placed segment of LRF.
  • the backsheet was then removed from the laminator and allowed to cool.
  • PTFE polytetrafluoroethylene
  • Fig. 5 A and 5B show a portion of the pseudo PV module of example Clp created using a smooth wooden roller to apply the LRF to the back sheet before and after lamination, respectively.
  • Fig. 5B shows evidence of entrapped air bubbles in the adhesive layer between the LRF and the backsheet after lamination.
  • Fig. 6 A and 6B show a portion of the pseudo PV module of example Exlp before and after lamination, respectively.
  • the adhesive Prior to lamination, the adhesive appears to have a slight lateral pattern due to the ridges in the groove roller exerting greater force on the adhesive layer during roll down (i.e. first regions) than the areas corresponding to the roller’s grooves (i.e. second regions) as shown in Fig 6A. No air bubbles became entrapped during lamination as shown in Fig. 6B.

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Abstract

L'invention concerne un procédé d'application d'un adhésif sur un substrat pour atténuer le piégeage de bulles d'air pendant un procédé de stratification sous vide. Le procédé comprend la mise en contact de l'adhésif avec une surface du substrat et l'application d'une force périodique à l'adhésif le long de la direction longitudinale de manière à créer des premières régions ayant une première force d'adhérence au substrat et des secondes régions ayant une seconde force d'adhérence au substrat, la seconde force d'adhérence étant inférieure à 90 % de la première force d'adhérence.
PCT/IB2021/052318 2020-03-27 2021-03-19 Procédé de stratification amélioré WO2021191757A1 (fr)

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Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1967870A1 (fr) * 2007-03-06 2008-09-10 Rohm and Haas Denmark Finance A/S Affichage comprenant un film de redirection de la lumière doté d'une épaisseur variable
US20100319754A1 (en) * 2009-02-19 2010-12-23 Sajjad Basha S Photovoltaic module configuration
JP2011073389A (ja) * 2009-10-01 2011-04-14 Toppan Printing Co Ltd 光学用フィルムの製造方法
EP2328185A1 (fr) * 2009-09-28 2011-06-01 Toyota Jidosha Kabushiki Kaisha Procédé de fabrication de module de pile solaire et précurseur pour module de pile solaire
US20140083481A1 (en) * 2011-05-09 2014-03-27 3M Innovative Properties Company Photovoltaic module
US9276151B2 (en) 2011-11-04 2016-03-01 3M Innovative Properties Company Polyolefin adhesive material for use in solar modules
US9379263B2 (en) 2011-11-04 2016-06-28 3M Innovative Properties Company Durable polyolefin adhesive material for solar modules
US20180013027A1 (en) 2016-07-07 2018-01-11 3M Innovative Properties Company Adhesive for light redirecting film
US10205041B2 (en) 2015-10-12 2019-02-12 3M Innovative Properties Company Light redirecting film useful with solar modules
US20190237601A1 (en) * 2018-01-30 2019-08-01 3M Innovative Properties Company Device, solar cell module, making method and installing method
US20190237603A1 (en) 2018-01-30 2019-08-01 3M Innovative Properties Company Light redirecting films and its making method and photovoltaic modules

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1967870A1 (fr) * 2007-03-06 2008-09-10 Rohm and Haas Denmark Finance A/S Affichage comprenant un film de redirection de la lumière doté d'une épaisseur variable
US20100319754A1 (en) * 2009-02-19 2010-12-23 Sajjad Basha S Photovoltaic module configuration
EP2328185A1 (fr) * 2009-09-28 2011-06-01 Toyota Jidosha Kabushiki Kaisha Procédé de fabrication de module de pile solaire et précurseur pour module de pile solaire
JP2011073389A (ja) * 2009-10-01 2011-04-14 Toppan Printing Co Ltd 光学用フィルムの製造方法
US20140083481A1 (en) * 2011-05-09 2014-03-27 3M Innovative Properties Company Photovoltaic module
US9276151B2 (en) 2011-11-04 2016-03-01 3M Innovative Properties Company Polyolefin adhesive material for use in solar modules
US9379263B2 (en) 2011-11-04 2016-06-28 3M Innovative Properties Company Durable polyolefin adhesive material for solar modules
US10205041B2 (en) 2015-10-12 2019-02-12 3M Innovative Properties Company Light redirecting film useful with solar modules
US20180013027A1 (en) 2016-07-07 2018-01-11 3M Innovative Properties Company Adhesive for light redirecting film
US20190237601A1 (en) * 2018-01-30 2019-08-01 3M Innovative Properties Company Device, solar cell module, making method and installing method
US20190237603A1 (en) 2018-01-30 2019-08-01 3M Innovative Properties Company Light redirecting films and its making method and photovoltaic modules

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