HK1228103A1 - Photovoltaic modules and methods of making the same - Google Patents

Description

Photovoltaic module and method for manufacturing same

Technical Field

The present invention relates to photovoltaic modules, and more particularly, to methods useful for using the adhesion of coating compositions for the coating and sealing of photovoltaic modules.

Background

Photovoltaic modules generate electricity by converting electromagnetic energy into electrical energy. Photovoltaic modules use encapsulant materials to provide durability, weatherability, and increased service life, particularly in open air operating environments.

Many types of thin film photovoltaic modules have been developed. Although there are a variety of materials and configurations in thin film technology, most thin film photovoltaic modules include the following basic elements: a transparent front layer, which may be glass, a transparent polymer, or a transparent coating; a transparent, conductive top layer or grid, which carries away the current; a thin semiconductor sandwich structure (sandwich) that forms a junction to separate charges; a back contact, which may be a metal film; a sealant layer; and a backing plate (backsshet) which protects from the environment and which provides support to the module if desired. As used herein, the term "layer" refers to a thickness or piece of material that can be used to cover or coat a surface or body.

Bulk photovoltaic modules include front side transparencies, such as glass sheets or pre-formed transparent polymer sheets (e.g., polyimide sheets); sealants such as Ethylene Vinyl Acetate (EVA); a photovoltaic cell comprising a wafer of photovoltaic semiconductor material such as crystalline silicon (c-Si); a back sealant and a back sheet. Bulk photovoltaic modules are typically manufactured in a batch or semi-batch vacuum lamination process, where the module components are pre-assembled into a module pre-assembly. The preassembly process includes depositing a sealing material on the front side transparency, positioning the photovoltaic cells and electrical interconnects on the encapsulant material, depositing additional encapsulant material on the photovoltaic cell assembly, and depositing a back sheet on the back side encapsulant material to complete the module preassembly. The module pre-assembly is placed in a specialized vacuum lamination apparatus that uses a flexible (compliant) film compression module assembly and cures the sealant material under reduced pressure and elevated temperature conditions to produce a laminated photovoltaic module. The process effectively laminates the photovoltaic cells between the front transparent layer and the back sheet, as the intermediate encapsulant material secures and seals the photovoltaic cells. A similar lamination process can be used to manufacture thin film photovoltaic modules in which the encapsulant material and backsheet are laminated to a front side transparency containing a deposited photovoltaic thin film layer.

The information described in this background section is not admitted to be prior art.

Disclosure of Invention

A method of making a photovoltaic module includes depositing a sealing material on at least a portion of a photovoltaic cell, curing the sealing material, and treating at least a portion of a surface of the cured sealing material. The method further includes depositing a liquid coating composition on at least a portion of the treated sealant and curing the liquid coating composition to form a primer coating.

The photovoltaic module includes a front side transparency, a photovoltaic cell, an encapsulant material deposited on at least a portion of the photovoltaic cell, a treated surface of at least a portion of the encapsulant material, and a bottom side coating deposited on at least a portion of the treated surface of the encapsulant material.

It is to be understood that the invention disclosed and described in this specification is not limited to this summary of the invention.

Brief Description of Drawings

The various features and characteristics disclosed and described in this specification, both as non-limiting and non-exhaustive, may be better understood with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram showing a bulk photovoltaic module of the present invention comprising a protective coating system;

FIG. 2 is a schematic diagram showing a thin film photovoltaic module of the present invention comprising a protective coating system;

FIG. 3 is a schematic diagram illustrating the process of the present invention for making a photovoltaic module comprising a protective coating system; and

FIGS. 4A-4F are photographs of a cured silicone sealant on glass with a liquid topcoat applied; FIG. 4A shows the back side of a coated glass sample A, which was coated with a polyurea resin primer coating, after cross-hatch adhesion (cross-hatch) testing before and after 10 days of exposure to moist heat; FIG. 4B shows the backside of coated glass sample B after cross-hatch adhesion test with DOW before and after 10 days of exposure to moist heat1200OS primer and polyurea resin basecoat; FIG. 4C shows the back side of a coated glass sample C treated with a corona discharge and polyurea resin primer coating after cross-hatch adhesion testing before and after 10 days of exposure to moist heat; FIG. 4D shows the back side of a coated glass sample D after cross-hatch adhesion testing before and after 10 days of exposure to moist heatCoating a fluoropolymer resin bottom coating; FIG. 4E shows the backside of coated glass sample E after cross-hatch adhesion test before and after 10 days of exposure to moist heat with DOW1200OS primer andcoating a fluoropolymer resin bottom coating; and FIG. 4F shows the back side of a coated glass sample F after cross-hatch adhesion test with corona discharge and after 10 days of exposure to moist heatThe fluoropolymer resin base coat is treated.

The reader should appreciate the foregoing details, as well as others, upon considering the following detailed description of non-limiting and non-exhaustive inventions in accordance with the present specification.

Detailed Description

The invention described herein relates to protective coating systems that can provide advantages such as superior durability, moisture barrier, abrasion resistance, etc. to photovoltaic modules.

A photovoltaic module is described. The photovoltaic module includes a front side transparency, a photovoltaic cell, an encapsulant material deposited on at least a portion of the photovoltaic cell, a treated surface of at least a portion of the encapsulant material, and a bottom side coating deposited on at least a portion of the treated surface of the encapsulant material. The encapsulant encapsulates the photovoltaic cell and includes a treated surface. The treated surface of the sealing material may comprise a surface of a cured layer formed from a flowable coating composition, wherein at least a portion of the surface is treated with a corona discharge, a plasma, an ultraviolet ozone, a plume discharge, a brush discharge, a glow discharge, or any combination thereof.

The term "front side transparency" as used herein refers to a material that is transparent to electromagnetic radiation in the wavelength range that is absorbed by the photovoltaic cell to generate electricity. The front side transparency can include a planar sheet of transparent material that includes an outwardly facing surface of the photovoltaic module. Any suitable transparent material may be used as the front side transparency, including, but not limited to, glass such as silicate glass, and polymers such as polyimide, polycarbonate, and the like, or other planar sheet materials that are transparent to electromagnetic radiation in the wavelength range that can be absorbed by the photovoltaic cell and used to generate electricity within the photovoltaic module. The term "transparent" as used herein refers to the property of a material through which at least a portion of incident electromagnetic radiation passes with negligible attenuation within the visible light spectrum (i.e., about 350 to 750 nanometers wavelength).

As will be apparent to those skilled in the art and as used herein, the term "photovoltaic cell" refers to a photovoltaic layer that is capable of generating a voltage when exposed to radiant energy. The photovoltaic layer may include a plurality of layers. For example, the photovoltaic layer may include an intermediate layer surrounded on each side by other layers. The intermediate layer (which may itself comprise multiple layers) comprises a voltage or electron generating material; i.e. a semiconductor material. The electron generating material may include, for example, amorphous silicon, thin film crystalline silicon, copper indium diselenide (copper indium diselenide), cadmium telluride ("CdTe"), and/or similar materials. The electron generation layer may include alternating n-type and p-type semiconductor layers to form a junction, which may be multi-junction or single junction. The intermediate layer may be sandwiched between two other layers, both of which are electrically conductive. The first layer closest to the transparent cover (superstate) may comprise a transparent conductive oxide such as indium tin oxide. In addition, there may be a second conductive layer on the opposite side of the intermediate layer. The second conductive layer may comprise a metal layer, such as aluminum, which may be deposited by, for example, sputtering. It should be understood that the electron generating material needs to be exposed to radiant energy on at least one side. Therefore, the layer on one side of the electron generating material should be transparent to such energy. Although exemplary photovoltaic layers are described above, any photovoltaic layer may be used in accordance with the present invention.

The photovoltaic cell of the present invention includes a transparent cover layer on one side of the photovoltaic layer. The transparent cover layer is transparent to radiant energy, particularly light, since it is this energy that will generate an electrical current in the electron generating layer. The cover layer may comprise a plate made of glass or a transparent polymer such as polyimide. Suitable capping layers are commercially available from afgraphics, Kingsport, IN, USA, and may be purchased as such (plain) or as a form on which a conductive oxide has been deposited. Although as many layers may be deposited and desired between the cover layer and the electron generating layer, as noted above, such layers should be transparent to allow exposure of the electron generating material to radiant energy. The thin film photovoltaic cells of the present invention also include a protective coating as an encapsulant material.

The encapsulant may comprise a flowable coating composition which is curable to a transparent layer after deposition. As used herein, the term "transparent" means that the sample exhibits a transmittance of over 85%, as evaluated under ASTM E308-06 "Standard practice for calculating the Colors of Objects by Using the Commission International de 1' Eclairage (CIE)", developed by ASTMInternational, West Conshohocken, Pa, USA. For example, the term "clear" means that a sample deposited with a 10 mil thick film on solarphe PV glass (3.2mm glass) exhibits a transmission of over 85%, using ASTM E308-06 standard (using a standard of 3.2mm glass)A 7 spectrophotometer, commercially available from X-Rite, inc., Grand Rapids, Michigan, USA), evaluated using CIE system Y values of D65 (incandescent lamp) illumination and a 10 ° standard observer. The term "flowable" as used herein to describe a flowable coating composition for use as a sealant includes liquids, powders, and/or other materials in a shape that can flow into or fill a space.

As used herein, the term "cured" (as used herein) refers to the state of a liquid coating composition in which a film or layer formed from the liquid coating composition is at least cured to be touch-dry (set-to-touch). As used herein, the terms "cure" and "curing" refer to the development of a liquid coating composition from a liquid state to a cured state, as well as the physical drying of the coating composition (i.e., a thermoplastic coating composition) and/or the chemical crosslinking of components in the coating composition (i.e., a thermoset coating composition) that involves evaporation of the solvent or carrier.

As used herein, the term "treating", "treated", "treating" or similar terms refers to a modification, manipulation, or chemical or physical modification of a substrate surface to create a surface that is altered from its original state. For example, treating at least a portion of the surface of the cured sealing material may include treating at least a portion of the surface of the cured sealing material opposite the front transparency with a corona discharge, a plasma, an ultraviolet ozone, a plume discharge, a brush discharge, a glow discharge, a texturing process, a primer coating, or the like, or any combination thereof.

The treated surface may include at least a portion of the surface treated with corona discharge, plasma, flame system, atmospheric plasma, plume discharge, brush discharge, glow discharge, and/or ultraviolet ozone, etc., or any combination thereof. These surface treatments cause changes in the surface energy and bonding ability (bonding ability) of the sealing material by excitation of molecules due to corona or discharge.

As used herein, the terms "corona discharge" and "corona treatment" refer to surface modification techniques that use a low temperature corona discharge plasma to impart changes in surface properties. The corona plasma is generated by applying a high voltage to a sharp electrode tip (which forms a plasma at the tip of the electrode tip). A linear array of electrodes is typically used to generate a corona plasma curtain (curl). A material such as plastic, fabric, or paper may be passed through the corona plasma curtain, thereby altering the surface energy of the material. Corona discharge can occur when the electric field strength around the conductor can be high enough to form a conductive region, but not high enough to create an arc with an adjacent object.

Corona treatment systems may be comprised of two main components: power supply and processor workstation (station). The processor may apply power to the material surface via an electrode pair (one electrode at high potential and a roll of support material at ground potential) through an air gap. Only the material side facing the high potential electrode may be activated to provide an increase in surface energy. Electrons generated in the corona discharge may impinge on the material surface with twice or three times the energy sufficient to break molecular bonds on the material surface. The radicals generated from the corona discharge treatment then rapidly react with the oxidizing molecules to form an oxide layer on the surface of the material. Therefore, when the sealing material is treated with corona discharge, the oxide layer formed may increase the surface energy of the sealing material, promote better wetting, and may deposit reactive polar groups such as hydroxyl groups, carbonyl groups, and amide groups on the surface of the sealing material. Surface treatment of the seal material with a corona discharge can be accomplished using a hand-held corona treater. For example, surface corona discharge treatment may be accomplished using a BD-20AC laboratory corona treater (commercially available from Electro-technical Products, Chicago, Illinois). The BD-20AC laboratory corona processor may be implemented at a distance from the instrument to the surface ranging from 1/8 inches (0.32cm) to 1 inch (2.54cm) and at a voltage input of 115V.

At least a portion of the surface of the sealing material may be treated with a flame system. When the combustible gas and air combine and burn to form a blue flame, the flame system creates a flame plasma field. Short exposures to particles in a flame can affect the distribution and density of electrons at the surface of the seal material. Much like corona discharge, the flame system acts to polarize surface molecules through oxidation and deposit other functional chemical groups that further promote surface diffusion and adhesion.

As used herein, "plasma" functionalization and "plasma discharge" activation refer to a method of functionalizing a surface by means of a plasma process. Plasma may refer to ionized gas or ionized ambient air (which contains not only ions but also radicals, electrons, and molecular fragments). The interaction of these excited species with a solid surface placed opposite the plasma results in chemical and physical modification of the material surface. The effect of the plasma on a given material may be determined by the chemical reaction between the surface and the reactive species present in the plasma. At low exposure energies typically used for surface treatment, plasma surface interactions only alter the surface of the material; the influence can be limited to regions of only a few molecular layer depths without changing the bulk property of the substrate. For example, dissipation of energy transfer in solids through a variety of chemical and physical processes can lead to a unique type of surface modification, which is a reaction with the surface from a few hundred angstroms to 10 microns in depth, but does not change the bulk properties of the material.

The surface changes caused by plasma treatment depend on the composition of the surface and the gas used. The gas or mixture of gases used for plasma treatment of the polymer may include nitrogen, argon, oxygen, helium, nitrous oxide, water vapor, halogens, carbon dioxide, methane, ammonia, and the like, or any combination thereof. Each gas produces a unique plasma composition and results in different surface characteristics. For example, the surface energy can be increased very quickly and efficiently by plasma-induced oxidation. Depending on the chemistry of the polymer and the source gas, partial substitution of molecules into the surface can make the polymer very wettable.

At least a portion of the surface of the sealing material may be treated using an atmospheric pressure plasma discharge or an atmospheric pressure plasma treatment (APT). Like corona discharge, atmospheric plasma discharge can be generated at atmospheric pressure. Instead of using air, this method relies on depositing specific chemical groups on the substrate surface to improve its surface energy and adhesion properties of other gases. Atmospheric pressure plasma discharge processes act on the surface of materials by exposing the polymer surface to a low temperature, high density glow discharge device. This apparatus may include a chamber containing spaced-apart (spaced-apart) electrodes having opposing surfaces. A relatively inert gas such as helium or argon may be supplied into the chamber. Glow discharge may occur by energizing the electrodes by radio frequency power amplifiers, microwaves, or alternating or direct current (energize) to perform plasma excitation that results in surface treatment of the material. The free electrons gain energy from an applied high frequency electric field (or other energy source), collide with neutral gas molecules and transfer energy, splitting the molecules to form a number of reactive species.

A wide range of parameters can affect the physical properties of the plasma and subsequently the surface chemistry resulting from plasma modification. Process parameters, such as gas type, process power, process time, and operating pressure, may be varied by the user; however, system parameters, such as electrode position, reactor design, gas inlet and vacuum, are set by the design of the plasma apparatus. This wide range of parameters provides greater control over the plasma process than is provided by many high-energy radiation processes.

As used herein, the term "ultraviolet ozone", "UV-ozone" or "UVO" refers to the use of ultraviolet light and ozone to simultaneously clean and modify the molecular surface of a solid. Organic anti-adhesion coatings, such as hydrocarbon and fluorocarbon based self-assembling organosilanes and siloxanes, can be treated with UVO to improve adhesion properties. UVO can be used to selectively treat the surface of a coating segment by simultaneously exposing the surface to ultraviolet light at multiple wavelengths, which excites and breaks up organic molecules of the anti-adhesion coating. UVO processes can generate atomic oxygen from molecular oxygen and ozone such that organic molecules react with the atomic oxygen to form volatile products that can be dissipated, resulting in the removal of the coating surface layer. UVO can be performed with ultraviolet light at two wavelengths, one around 184.9nm and the other around 253.7 nm. During the UVO process, organic molecules such as silanes may be excited and split by the absorption of short wavelength UV radiation. Atomic oxygen can be generated simultaneously when molecular oxygen is split by 184.9nm radiation and ozone is split by 253.7nm radiation. 253.7nm radiation can be absorbed by most organic and ozone. The organic molecules may react with atomic oxygen to form volatile products that may be dissipated, resulting in the removal of the surface layer of the anti-adhesion coating.

Physical and chemical advantages of the treated surface of the sealing material may include altering the sealing material surface energy and bonding capability through molecular excitation caused by corona or electrical discharge. The treated surface of the sealing material provides the sealing material with the adhesive strength of the bottom coating. As used herein, the term "adhesion" refers to the ability of a first compound to attach, adhere, or adhere to a second compound or surface.

As described above, the cured sealing material surface may comprise at least a portion of the surface treated with corona discharge, plasma, ultraviolet ozone and/or may also be a deposition treated surface using a primer coating. As described above, the photovoltaic module of the present invention may further include a primer coating. For example, the photovoltaic module can further include a primer coating deposited between the bottom coating and the cured encapsulant or between the bottom coating and the treated surface of the encapsulant. As used herein, the terms "primer coating," "primer coating composition," "primer," or similar terms refer to a coating or coating composition that forms a basecoat (undercoating) deposited on a substrate upon which a topcoat may be deposited. The primer coating may provide corrosion protection. For example, the primer may include silicone and/or octamethyltrisiloxane. The primer coating may comprise any suitable coating composition, such as DOW commercially available from Dow Corning Corporation, Midland, Michigan, USA1200OS primer (primer for silicone adhesive/sealant), silicone coating, octamethyltrisiloxane coating, or any combination thereof.

At least a portion of the surface of the cured sealing material may be a surface treated with a texturing process. The texturing process may be used as a treatment of the surface of the sealing material alone or in combination with a surface treatment using corona discharge, plasma, ultraviolet ozone, plume discharge, brush discharge, glow discharge and/or primer coating. As used herein, the term "texturing" refers to a process that provides topological changes in the surface of a material. For example, the textured surface of the sealing material may comprise a layer of fabric covering across the surface of the sealing material and subsequently removing the fabric after heat curing to provide an embedded or embossed pattern in the surface of the thermosetting sealing material. Other examples of texturing processes for the surface of the sealing material may include printing (embossing) or embossing (embossing) processes, engraving or molding processes, scoring (scoring), burning and/or cutting, cross-hatching or other patterns (grids, stripes, ridges, etc.), placed in or on the surface of the cured sealing material. The texturing process may include texturing at least a portion of the surface of the sealing material before, during, and/or after curing the sealing material. The texturing process of the present invention may include texturing at least a portion of the encapsulant surface before, during, and/or after additional treatment of the cured encapsulant (e.g., with corona discharge, plasma, and/or ultraviolet ozone).

The basecoat may include a cured polyurea resin formed from a liquid coating composition comprising a polyisocyanate, a polyamine, a diamine chain extender, and optionally an amine-functional silicone and/or a hydroxyl-functional silicone different from the polyamine. For example, the base coat 210 may include a polyurea layer, as described in U.S. patent application No.14/484,919, which is incorporated by reference herein. The coating composition may include an aliphatic composition comprising a polyamine including a polyaspartic acid ester or a cycloaliphatic polyaspartic acid ester, a diamine chain extender including a cycloaliphatic secondary amine, and an amine-functional siloxane.

Physical and chemical advantages of the bottom surface coating may include durability (robust) applications (applications), impact protection, high durability and abrasion resistance, and chemical and weather resistance. The primer coating may serve to protect the photovoltaic cells and/or photovoltaic modules from abrasion, corrosion, and/or environmental damage, and may provide a moisture barrier, durability, and/or extended life to the photovoltaic module. As used herein, the term "resin" refers to a composite comprising a liquid composition that hardens to a solid.

As used herein, the term "isocyanate" includes non-blocked isocyanate compounds that are capable of forming covalent bonds with reactive groups such as hydroxyl, thiol, or amine functional groups. Thus, isocyanate may refer to "free isocyanate" as would be understood by one skilled in the art. The isocyanate may be monofunctional (comprising one isocyanate function (NCO)). The isocyanate may be blocked and/or include any combination of isocyanates and/or isocyanate functional prepolymers. As used herein, the term "polyisocyanate" refers to an isocyanate that may be multifunctional (comprising two or more isocyanate functional groups (NCO)). Polyisocyanates include diisocyanates and diisocyanate reaction products including, for example, biuret, isocyanurate, urethane, urea, iminooxadiazinedione, oxadiazinetrione, carbodiimide, acylurea, allophanate groups, and any combination thereof. The polyisocyanate may be aromatic or aliphatic, including mixtures of aromatic and aliphatic polyisocyanates.

Suitable isocyanates and polyisocyanates can be numerous and widely varied. Such isocyanates may include those known in the art. Non-limiting examples of suitable isocyanates may include monomeric and/or polymeric isocyanates. The isocyanate may be selected from monomers, prepolymers, oligomers or blends thereof. The isocyanate of the present invention may be C₂-C₂₀Linear, branched, cyclic, aromatic, aliphatic, or any combination thereof.

Suitable isocyanates for use in the present invention may include, but are not limited to, isophorone diisocyanate (IPDI), which may be 3, 3, 5-trimethyl-5-isocyanato-methyl-cyclohexyl isocyanate; hydrogenated materials, such as cyclohexylene diisocyanate, 4' -methylenedicyclohexyl diisocyanate (H)₁₂MDI); mixed aralkyl diisocyanates, such as tetramethylxylyl diisocyanate, OCN-C (CH)₃)₂-C₆H₄C(CH₃)₂-NCO; doya (Asia-Asia disease)Methyl isocyanates such as 1, 4-tetramethylene diisocyanate, 1, 5-pentamethylene diisocyanate, 1, 6-hexamethylene diisocyanate (HMDI), 1, 7-heptamethylene diisocyanate, 2, 4-and 2, 4, 4-trimethylhexamethylene diisocyanate, 1, 10-decamethylene diisocyanate and 2-methyl-1, 5-pentamethylene diisocyanate and any mixtures thereof.

Non-limiting examples of aromatic isocyanates for use in the present invention may include, but are not limited to, phenylene diisocyanate, Toluene Diisocyanate (TDI), xylene diisocyanate, 1, 5-naphthalene diisocyanate, chlorophenylene 2, 4-diisocyanate, bitoluene (bitoluene) diisocyanate, o-dianisidine diisocyanate, tolidine diisocyanate, alkylated benzene diisocyanate, methylene interrupted aromatic diisocyanates such as methylene diphenyl diisocyanate, 4 ' -isomers including alkylated analogs (MDI) such as 3, 3 ' -dimethyl-4, 4 ' -diphenylmethane diisocyanate, polymeric methylene diphenyl diisocyanate, or any mixture thereof.

Isocyanate monomers may be used in the present invention. It is believed that the use of isocyanate monomers (i.e., residue-free monomers from the preparation of the prepolymer) can reduce the viscosity of the polyurea composition and thus increase its flowability, and can provide improved adhesion of the polyurea coating to a previously applied coating and/or an uncoated substrate. At least 1 wt%, or at least 2 wt%, or at least 4 wt% of the isocyanate component may include at least one isocyanate monomer.

The isocyanates may include oligomeric isocyanates such as, but not limited to, dimers such as uretdiones of 1, 6-hexamethylene diisocyanate, trimers such as biurets and isocyanurates of 1, 6-hexane diisocyanate, and isocyanurates, allophanates, and polymeric oligomers of isophorone diisocyanate. Modified isocyanates may also be used, including but not limited to carbodiimides and uretonimines (uretone-imine), and any mixtures thereof. Suitable materials include, but are not limited to, those available under the name DESMODUR from Bayer Corporation of Pittsburgh, Pa., USA, and include DESMODUR N3200, DESMODUR N3300, DESMODUR N3400, DESMODUR XP 2410, and DESMODUR XP 2580.

The isocyanate component of the present invention may include an isocyanate functional prepolymer formed from a reaction mixture comprising an isocyanate and other materials. Any isocyanate known in the art such as those described above may be used in the formation of the prepolymer. As used herein, an isocyanate functional prepolymer refers to the reaction product of an isocyanate and a polyamine and/or other isocyanate reactive groups (such as polyols); the isocyanate functional prepolymer has at least one isocyanate functional group (NCO).

The isocyanate functional prepolymer may include an isocyanate that may be pre-reacted with a material comprising a flame retardant material, such as a phosphorus-containing polyol. Suitable isocyanate functional prepolymers containing flame retardant materials are disclosed in paragraphs [0017] - [0023] of U.S. serial No. 12/122,980, incorporated herein by reference. As described in that excerpt, the phosphorus-containing polyol may itself be the reaction product of a phosphorus-containing polyol, sometimes referred to as a "starter" phosphorus-containing polyol, and other compounds.

However, the polyol used in the formation of the prepolymer may not comprise a phosphorus-containing polyol. Suitable phosphorus-free polyols may include polytetrahydrofuran materials such as those sold under the trade name TERATHANE (e.g., TERATHANE 250, TERATHANE 650, and TERATHANE 1000 available from Invista corporation).

The amine component may include a suitable amine. The viscosity of the second component can be 1700 centipoise or less, such as 1500 centipoise or 1000 centipoise or less, at a temperature of 7 ℃ or more, such as a temperature ranging from 7 ℃ to 13 ℃. The amine component may be referred to herein as a "curing agent" because it reacts or cures with isocyanate to form a polyurea. The ratio of isocyanate group equivalents to amine group equivalents may be greater than 1, and the isocyanate component and the amine component may be applied to the substrate at a volume mixing ratio of 1: 1.

As used herein, the term "polyamine" refers to a compound comprising at least two free primary and/or secondary amine groups. Suitable polyamines are numerous and can vary widely. Such polyamines may include those known in the art. Non-limiting examples of suitable polyamines can include, but are not limited to, primary and secondary amines, and any mixtures thereof, such as any of those listed herein. Amine-terminated polyureas can also be used. Amines comprising tertiary amine functionality may be used, provided that the amine further comprises at least two primary and/or secondary amino groups. In the present invention, wherein the isocyanate functional prepolymer comprises a polyamine, the ratio of isocyanate group (NCO) equivalents to amine group (NH) equivalents may be greater than 1.

For example, the amine may comprise a monoamine, or a polyamine having at least two functional groups, such as a di-, tri-, or higher functional amine, and any mixtures thereof. Furthermore, the amines may be aromatic or aliphatic, such as cycloaliphatic, or any mixture thereof. Non-limiting examples of suitable monoamines include aliphatic polyamines such as, but not limited to, ethylamine, isopropylamine, butylamine, pentylamine, hexylamine, cyclohexylamine, and benzylamine. Suitable primary polyamines include, but are not limited to, ethylenediamine, 1, 2-propylenediamine, 1, 4-butylenediamine, 1, 3-pentylenediamine (DYTEK EP, Invista), 1, 6-hexylenediamine, 2-methyl-1, 5-pentylenediamine (DYTEK A, Invista), 2, 5-diamino-2, 5-dimethylhexane, 2, 4-and/or 2, 4, 4-trimethyl-1, 6-diamino-hexane, 1, 11-diaminoundecane, 1, 12-diaminododecane, 1, 3-and/or 1, 4-cyclohexanediamine, 1-amino-3, 3, 5-trimethyl-5-aminomethyl-cyclohexane, 2, 4-and/or 2, 6-hexahydrotoluylenediamine, 2, 4 '-diaminodicyclohexylmethane, 4' -diaminodicyclohexylmethane (PACM-20, Air Products) and 3, 3 '-dialkyl-4, 4' -diaminodicyclohexylmethane (such as 3, 3 '-dimethyl-4, 4' -diaminodicyclohexylmethane (DIMETHYL DICYKAN or LAROMIN C260, BASF; ANCAMINE 2049, Air Products) and 3, 3 '-diethyl-4, 4' -diaminodicyclohexylmethane), 2, 4-and/or 2, 6-diaminotoluene, 3, 5-diethyltoluene-2, 4-diamine, 3, 5-diethyltoluene-2, 6-diamine, 3, 5-dimethylthio-2, 4-toluenediamine, 3, 5-dimethylthio-2, 4-toluene diamine, 2, 4 '-and/or 4, 4' -diaminodiphenylmethane, dipropylene triamine, bis (hexylene) triamine, or any combination thereof. Polyoxyalkylene amines are also suitable. The polyoxyalkylene amine includes two or more primary or secondary amino groups attached to the backbone, for example, from propylene oxide, ethylene oxide, butylene oxide, or any combination thereof. Examples of such amines include those available under The name JEFFAMINE, such as, but not limited to, JEFFAMINE D-230, D-400, D-2000, HK-511, ED-600, ED-900, ED-2003, T-403, T-3000, T-5000, SD-231, SD-401, SD-2001, and ST-404(Huntsman Corporation, The Woodlands, TX, USA). These amines have a molecular weight ranging from about 200 to 7500.

The polyamines used in the present invention may include polyaspartic esters, more specifically polyaspartic esters having the structure:

wherein n is an integer from 2 to 4 and X represents an organic group having the valence of n and being inert towards isocyanate groups. X may be an aliphatic residue such as a cycloaliphatic residue. As used herein, the term "cycloaliphatic" means an aliphatic structure comprising one or more non-aromatic hydrocarbon rings and optionally also a non-cyclic aliphatic carbon chain. Secondary cycloaliphatic diamines may also be used. Suitable cycloaliphatic diamines include, but are not limited to, JEFFLINK754(Huntsman Corporation, The Woodlands, TX, USA), CLEARLINK1000(Dorf-Ketal Chemicals, LLC), and aspartate-functional amines such as those available under The name DESMOPHEN, such as DESMOPHEN NH 1220, DESMOPHEN NH 1420, and DESMOPHEN NH 1520(Bayer Materials Science, LLC.). Other suitable secondary amines that can be used include the reaction product of a material comprising primary amine functionality (such as those described herein) and acrylonitrile. For example, the secondary amine can be the reaction product of 4, 4' -diaminodicyclohexylmethane and acrylonitrile. Alternatively, the secondary amine may be the reaction product of isophorone diamine and acrylonitrile, such as POLYCLEAR 136 (available from BASF/Hansen Group LLC).

Other amines that may be used include adducts of primary polyamines with monoepoxides or polyepoxides, such as the reaction product of isophorone diamine with CARDURA E-10P. The additional amines may include trifunctional polyoxypropylene primary diamines or trifunctional aliphatic polyether primary amines. Combinations of different polyamines including any combination of the polyamines described above may be used.

The polyurea compositions of the present invention may also include one or more amines, such as those described in U.S. patent application serial nos. 11/611,979, 11/611,984, 11/611,988, 11/611,982, and 11/611,986, all of which are incorporated herein by reference in their relevant part.

The phrase "diamine chain extender" as used herein refers to a difunctional polyamine that contributes to the polymeric chain extension of molecules within the undercoat layer. Diamine chain extenders include primary diamines, secondary diamines, diamines containing both primary and secondary amino groups, diimines, and any combination thereof. Amino groups (including primary and secondary amino groups) or imino groups may be bonded to aliphatic residues such as cycloaliphatic residues or non-cycloaliphatic residues. Thus, the diamine chain extender may comprise an aliphatic primary diamine, an aliphatic secondary diamine, an alicyclic primary diamine, an alicyclic secondary diamine, a non-alicyclic primary diamine, a non-alicyclic secondary diamine, an aliphatic diimine, and any combination thereof. Specific examples of diamine chain extenders include cycloaliphatic secondary diamines obtained from isophorone, such as those commercially available from Huntsman Corporation, The Woodlands, TX, USA754 a diamine.

Alternatively, the silicone polymer may comprise an amine-functional and/or a hydroxyl-functional silicone. As used herein, the term "silicone" refers to a polyorganosiloxane (also referred to as "polysiloxane" or "siloxane"), which can be a monomer or a polymer. As used herein, the term "hydroxy-functional silicone" refers to a silicone having hydroxyl groups. The present invention may include amine-functional and/or hydroxyl-functional silicones to improve the physical properties and long-term performance of the basecoat. As used herein, the term "amine-functional silicone" refers to a silicone having a primary or secondary amine group. The present invention may include amine-functional and/or hydroxyl-functional silicones to improve the physical properties and long-term performance of the basecoat.

Cured fluoropolymer resins may be used as an alternative to polyurea resins. As used herein, the term "fluoropolymer" refers to a fluorocarbon-based polymer having multiple strong carbon-fluorine bonds. Fluoropolymers may be characterized by high solvent resistance, acid resistance, and base resistance. Fluoropolymers can be made from monomers such as vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoropropyl vinyl ether, perfluoromethyl vinyl ether, chlorotrifluoroethylene, and can be co-polymers with non-fluorinated monomers such as ethylene and propylene.

Any suitable fluoropolymer may be used in accordance with the present invention. Examples include, but are not limited to, perfluoroalkoxy tetrafluoroethylene copolymer (PFA), ethylene chlorotrifluoroethylene (E-CTFE), ethylene tetrafluoroethylene (E-TFE), poly (vinylidene fluoride) (PVDF), poly (tetrafluoroethylene), poly (vinyl fluoride), poly (trifluoroethylene), poly (chlorotrifluoroethylene) (CTFE), and/or poly (hexafluoropropylene). Mixtures of two or more suitable fluoropolymers may be used, as may copolymers, terpolymers, etc. of suitable fluoropolymers. The quality of fluoropolymer resins and oligomeric additives makes them ideal solutions for applications requiring high solvent resistance, acid and base resistance and significant friction reducing capability. Such surfactant additives reduce surface energy while increasing chemical, UV, moisture, grease and stain resistance, and surface lubricity. For example,is a fluoropolymer resin commercially available from PPG Industries, inc.

Photovoltaic modules generate electricity by converting electromagnetic energy into electrical energy. To continue to be used in harsh operating environments, photovoltaic modules use encapsulant materials to provide durability and module life. "encapsulant," "sealed," "sealing," and similar terms refer to covering a component, such as a photovoltaic cell, with one or more layers of material such that the surface of the component is not exposed, thereby protecting the photovoltaic cell from the environment. As used herein, "back layer," "back sheet," "bottom coating," and similar terms refer to a layer that can be located on the side of the photovoltaic cell opposite the front side transparency.

As used herein, the term "encapsulant" refers to a polymeric material used in a photovoltaic module to adhere a photovoltaic cell to a front side transparency and/or a backsheet, and/or to encapsulate the photovoltaic cell within a covering of the polymeric material. The sealing material may comprise a silicone sealant, such as Dow Corning PV 6150 cell sealant commercially available from Do Corning Corporation, Midland, Michigan, USA. The sealing material may also contain adhesion promoting additives.

As used herein, the term "adhesion-promoting additive" refers to a composition, element, component, etc., that can be added to a sealant or sealant material to promote adhesion to a sealing surface. The adhesion promoting additive may include an isocyanate functional silane, a hydroxyl functional silane, an amine functional silane, or any combination thereof. As used herein, the term "hydroxy-functional silane" refers to a polysilane oligomer or polymer having hydroxy-functional groups. As used herein, the term "amine functional silane" refers to polysilane oligomers or polymers having primary and/or secondary amine groups. As used herein, the term "isocyanate functional silane" refers to a polysilane oligomer or polymer having isocyanate functional groups.

As schematically shown in fig. 1, a photovoltaic module may include a bulk photovoltaic module 100 including a plurality of electrically interconnected photovoltaic cells 102 adhered on a front side transparency 104. The photovoltaic cells 102 may be arranged such that front contacts (not shown) of the photovoltaic cells 102 face the front transparency 104. Photovoltaic module 100 can also include an encapsulant material 106 adjacent front side transparency 104. The encapsulant 106 may provide adhesion of the photovoltaic cell 102 to the front side transparency 104. Photovoltaic module 100 may also include electrical interconnects 108 that join or connect photovoltaic cells 102 applied to encapsulant material 106. As shown in fig. 1, an encapsulant material 106 encapsulates at least a portion of the front side transparency 104, the electrical interconnects 108, and the photovoltaic cells 102. The photovoltaic cell 102 may comprise a crystalline silicon wafer. The encapsulation material 106 may include a treated surface 110 of the encapsulation material 106 opposite the front side transparency 104. The treated surface 110 of the sealing material 106 may comprise a surface of a cured layer formed from a liquid coating composition, wherein at least a portion of the surface may be treated with corona discharge, plasma, ultraviolet ozone, plume discharge, brush discharge, glow discharge, luminescent discharge, or any combination thereof. Photovoltaic module 100 can also include a bottom surface coating 112 deposited on at least a portion of encapsulant material 106, on treated surface 110 of the encapsulant material, or any combination thereof.

Photovoltaic module 100 can also include an encapsulant material 106 adjacent front side transparency 104. The sealing material 106 may be applied or deposited on at least a portion of the front side transparency 104. The encapsulant material may seal at least a portion of photovoltaic cell 102. In addition, the encapsulant 106 may include a silicone encapsulant such as Dow Corning PV 6150. The sealing material may include a silicone sealant and an adhesion promoting additive.

The photovoltaic cells 102 and the electrical interconnects 108 may be disposed on the encapsulant layer 106 such that each photovoltaic cell 102 may be electrically connected to another cell. Photovoltaic cell 102 comprises a structure comprising a semiconductor wafer positioned between two conductive contacts. The semiconductor wafer of the present invention may comprise a crystalline silicon wafer. The first conductive contact may comprise a transparent conductive oxide layer deposited on one side of a crystalline silicon wafer or a semiconductor wafer. The second conductive contact may comprise a metal layer deposited on the opposite side of the crystalline silicon wafer or the semiconductor wafer. The photovoltaic cells 102 may include a bulk photovoltaic cell (e.g., ITO-and aluminum-coated crystalline silicon wafers). The present invention may include an assembly of photovoltaic cells 102 and electrical interconnects 108. Photovoltaic module 100 may include a plurality of light photovoltaic cells, each of which may include a crystalline silicon wafer. The photovoltaic cell may comprise a plurality of thin film photovoltaic cells, each of which may comprise a plurality of deposited photovoltaic layers (see fig. 2).

The photovoltaic module 100 can further include a treated surface 110 of the cured sealing material 106, the treated surface 110 of the cured sealing material 106 comprising a surface treated with any of the surface treatments and/or any combination of surface treatments previously described.

Photovoltaic module 100 can further include a protective or bottom coating 112. The bottom coating 112 may comprise a single coating layer or multiple coating layers. The base coat 112 may be derived from any number of coatings, including powder coating compositions, liquid coating compositions, and/or electrodeposition coatings. A durable, moisture and/or abrasion resistant protective coating may be used as a back side or sealant layer to reduce or eliminate corrosion associated with failure of the photovoltaic cell.

Although the photovoltaic module 100 shown in fig. 1 is a bulk photovoltaic module, the photovoltaic module may comprise a thin film photovoltaic module. As shown in fig. 2, thin-film photovoltaic module 200 may include a module including a front side transparency 202, a photovoltaic cell 204, an encapsulant 206 deposited over a portion of photovoltaic cell 204 and front side transparency 202, a treated surface 208 of encapsulant 206, and a bottom side coating 210 deposited over treated surface 208.

Front side transparency 202 may include a material transparent to electromagnetic radiation in a wavelength range that may be absorbed by photovoltaic cell 204 and used to generate electricity. The front side transparency may comprise a planar sheet of transparent material comprising an outwardly facing surface of the photovoltaic module 200. The front face transparency 202 may comprise the same or similar materials and may perform the same or similar functions as the front face transparency 104 described above in relation to the bulk photovoltaic module 100 shown in fig. 1.

The thin-film photovoltaic module 200 of fig. 2 can be fabricated by deposition of multiple thin-film photovoltaic cells 204, each thin-film photovoltaic cell 204 can include a deposited photovoltaic layer 212 on a plurality of front side transparencies 202. The plurality of deposited photovoltaic layers 212 may include a transparent conductive oxide layer or other transparent conductive film 214. Transparent conductive film 214 may be optically transparent and/or electrically conductive, providing a junction between front side transparency 202 and semiconductor active material layer 216. The transparent conductive film 214 may act as a window (window) for light to pass through to the underlying semiconductor active material layer 216 and/or may act as an ohmic contact for electrons to be output from the photovoltaic module 200. The transparent conductive film 214 may be made of a material having an incident light transmittance of more than 80% and a conductivity of more than 103S/cm for effective electron/hole transport. For example, the transparent conductive film 214 may include a transparent conductive oxide comprising one of indium tin oxide, fluorine doped tin oxide, doped zinc oxide, or any combination thereof. Transparent conductive film 214 can be deposited or grown on front side transparency 202 using a variety of deposition techniques. For example, a transparent conductive film can be deposited as follows: in a manufacturing technique using aerosol assisted pyrolysis deposition, Metal Organic Chemical Vapor Deposition (MOCVD), Metal Organic Molecular Beam Deposition (MOMBD), spray pyrolysis, Pulsed Laser Deposition (PLD), magnetron sputtering including thin films, or any combination thereof.

The transparent conductive film 214 may be in direct contact with the semiconductor active material layer 216. The layer of semiconductor active material 216 can include a layer of photovoltaic semiconductor material (e.g., in amorphous silicon, cadmium telluride, copper indium diselenide, or any combination thereof) deposited on the transparent conductive film 214. The layer of semiconductor active material 216 may function to generate electrons that may be used for conduction through the photovoltaic module 200.

The layer of semiconductor active material 216 may be in direct contact with the metal layer 218. The metal layer 218 may comprise, for example, aluminum, nickel, molybdenum, copper, silver, gold, or any combination thereof. The metal layer 218 may serve as a back contact to the semiconductor active material layer 216 for conducting current throughout the photovoltaic module 200. The metal layer 218 may be deposited on the semiconductor active material layer 216 using a variety of deposition techniques. For example, the metal layer 218 may be deposited on the semiconductor active material layer 216 using screen printing, thermal spraying, vapor deposition, chemical vapor deposition, or any combination thereof.

The photovoltaic module 200 can further include an encapsulant material 206 adjacent the thin film photovoltaic cell 204. Encapsulant material 206 can be deposited over photovoltaic cell 204 and at least a portion of front side transparency 202. For example, encapsulant material 206 encapsulates photovoltaic cells comprising thin film photovoltaic cells 204 adhered directly to front side transparency 202. The encapsulant material 206 may comprise the same or similar materials and perform the same or similar functions as the encapsulant material 106 described above in connection with the bulk photovoltaic module 100 shown in fig. 1. Further, the encapsulant 206 can include a cured transparent encapsulant coating deposited on at least a portion of one side of the thin film photovoltaic cell 204. The sealing material may include a cured and treated transparent sealing coating.

The surface of the encapsulant 206 opposite the thin film photovoltaic cell 204 may be treated to increase the surface energy in order to improve wettability and adhesion characteristics. Thus, the thin-film photovoltaic cell 204 can further include a treated surface 208 (comprising a surface treated with any of the surface treatments and/or combinations of any of the surface treatments described previously herein) of the cured encapsulant material 206. For example, the sealing material 206 may comprise a cured and corona discharge, plasma, and/or ultraviolet ozone treated silicone sealant. The treated surface 208 may be in direct contact with the bottom surface coating 210.

The base coat 210 may include a cured polyurea layer formed from a liquid coating composition. As used herein, the term "liquid coating" refers to a coating composition comprising a fixed volume in a liquid state. The base coat layer 210 of the present invention may include a polyurea layer formed of a coating composition that is sprayed and cured. The basecoat 210 may comprise a cured polyurea layer formed from a coating composition comprising a polyisocyanate, a polyamine, a diamine chain extender, and an amine-functional and/or hydroxyl-functional silicone, or a combination thereof.

The thin film photovoltaic module 200 has higher requirements for moisture barrier than the bulk photovoltaic module 100. For example, Copper Indium Gallium Selenide (CIGS) and CdTe thin film photovoltaic modules may include a thin transparent conductive oxide layer (which may be susceptible to moisture and oxygen) in a plurality of deposited photovoltaic layers. To provide a high moisture and oxygen barrier, the thin film photovoltaic module may include a glass front side transparency, a glass back sheet, and an edge seal. For example, the bottom surface coating 210 may be in direct contact with a glass backplane (not shown). In contrast, a photovoltaic module does not have the same sensitivity to moisture as a thin film photovoltaic module, although moisture can eventually lead to corrosion of the interconnecting tape (tabbing ribbon) and the bus bar. Thus, to provide moisture protection, a bulk photovoltaic module can include a glass front side transparency and a polymeric backsheet. For example, a crystalline silicon bulk photovoltaic module can include a glass front side transparency and a polymeric backsheet (including a fluoropolymer layer) comprising polyethylene terephthalate (PET). The bottom side coating 112 of the bulk photovoltaic module 100 can be in direct contact with a polymeric backsheet (not shown).

Referring back to fig. 1, depositing the primer coating 112 can include depositing a liquid coating composition on at least a portion of the treated sealant 110 and curing the liquid coating composition to form the primer coating 112. For example, depositing the primer coating 112 can include depositing a liquid coating composition on the photovoltaic cells 102 and at least a portion of the electrical interconnects 108 and curing the liquid coating composition to form a cured primer coating 112. Depositing the primer coating 112 can include depositing a liquid coating composition on at least a portion of the back side of the photovoltaic cell 102 opposite the front side transparency 104 and on the treated surface 110 of the cured encapsulant 106 and curing the liquid coating composition to form the cured primer coating 112.

A problem with previous two or more component polyurea resin coating systems and compositions may be that the combined liquid coating compositions can gel and cure quickly, which can limit pot life. For example, aliphatic primary polyamines can react rapidly with polyisocyanates, which can limit their commercial applications. However, efforts to reduce the crosslinking rate of the polyisocyanates and polyamines forming the polyurea resin coating, thereby increasing the pot life of the mixed coating composition, also tend to simultaneously increase the cure time of the liquid coating applied to the substrate.

Polyamines can give the base coat advantageous properties. For example, the polyamine component can reduce drying and/or curing time, provide cure at ambient temperature, and impart impact resistance, abrasion resistance, corrosion resistance, chemical resistance, and weatherability. Polyamines can be formulated with slower reaction rates to accommodate batch mixing and thinner film applications. In addition, the polyamine coating can be UV and light stable and can provide the beneficial properties of polyurea resins (fast cure, durability application, and 100% solids) as well as controlled Moisture Vapor Transmission Rate (MVTR) penetration. Thus, the bottom surface coating can provide rapid cure and gel time control at ambient temperature. For example, the primer coating may provide a cure time of 5-60 seconds and a gel time of 5-120 seconds.

The liquid coating composition of the present invention can be applied to or deposited on all or a portion of the backside of the cured encapsulant material of the photovoltaic module, photovoltaic cell and electrical interconnect, and can be cured using any suitable application technique to form a primer coating or layer thereon (e.g., a topcoat, a primer coating, a tie coat, a clear coat, etc.). For example, the coatings of the present disclosure may be applied by spraying, dipping, roll coating (rolling), brushing, roll coating (rolling), curtain coating, flow coating, slot die coating (slot die coating), and the like, or any combination thereof.

In the method of the present invention, wherein the sealant layer comprises a flowable coating composition applied to one side of the front transparency, the flowable coating composition can be applied using any of the application techniques described above.

The base coat may exhibit a Young's modulus in the range of 10MPa to 900MPa, or any subrange included therein, such as 10 to 800MPa, 100 to 500MPa, 200 to 400MPa, or 50 to 700 MPa. Young's modulus values were measured according to ASTM D822-02 standard test method for tensile properties of thin plastic sheets developed by ASTM International, West Conshooken, PA., USA.

The bottom coating may achieve an elongation in the range of 10% to 300%, or any subrange included therein, such as 10% to 50%, 15% to 25%, 18% to 24%, or 100% to 200%. Elongation values were measured according to ASTM D822-02 standard test method for tensile properties of thin plastic sheets developed by ASTM international, West Conshohocken, pa.

The base coat may exhibit a tensile strength in the range of 10MPa to 900MPa or any subrange included therein, such as 5MPa to 100MPa, 100MPa to 500MPa, 10MPa to 200MPa, or 50MPa to 100 MPa. Tensile strength values were measured according to ASTM D822-02 standard test method for tensile properties of thin plastic sheets developed by ASTM International, West Conshooken, PA., USA.

The base coat may exhibit a dry film thickness in the range of 0.5 to 50 mils, or any subrange included therein, such as 5 to 40 mils, 10 to 25 mils, 10 to 20 mils, or 10 to 15 mils. Dry film thickness values were measured using a Marathon electronic digital micrometer C0030025.

The base coat may exhibit a range of 1 to 1000g x mil/m²Water vapor transmission rate permeability (moisture vapor transmission rate) of, such as, 100 to 500g mil/m, day or any subrange included therein²Days, 50 to 400g mil/m²Days, 5 to 50g mil/m²Days or 20 to 40g mil/m²Days. Water vapor transmission permeability is measured using a Lyssy L80-5000 water vapor permeability analyzer, and water vapor transmission permeability values are measured according to the standard test method ASTM E-398 for water vapor transmission rates of sheets using dynamic relative humidity measurements developed by ASTM International, westcushohock, pa.

The base coat may exhibit a maximum permeation value ranging from 1 to 1000g x mil/m 2 x day, or any subrange included therein, such as from 1 to 500g x mil/m 2 x day, from 100 to 500g x mil/m 2 x day, from 500 to 1000g x mil/m 2 x day, or from 250 to 750g x mil/m 2 x day.

The primer coating may exhibit a dry insulation resistance of greater than 400M Ω, or may be greater than 500M Ω, greater than 1000M Ω, greater than 1500M Ω, or greater than 2000M Ω. The dry insulation resistance properties described above can be exhibited by a basecoat having a dry film thickness of less than 30 mils, or less than 25 mils, or less than 20 mils. For example, a primer coating less than 30 mils, less than 25 mils, or less than 20 mils thick can exhibit a dry insulation resistance greater than 500M Ω, greater than 1000M Ω, greater than 1500M Ω, or greater than 2000M Ω. Dry insulation resistance was measured using a DI-2000M insulation tester, and the dry insulation resistance value was measured according to International Electrotechnical Commission (IEC), International Standard, second edition (2005-04), "Crystalline silicon regenerative thermal (PV) modules-Design qualification and typepapproval" (IEC 61215: 2005).

The basecoat may comprise a topcoat that may comprise a dry (cured) film thickness in the range of 0.2 mils to 25 mils, or any subrange included therein, such as 1 mil to 10 mils, 0.5 mil to 15 mils, 10 mils to 20 mils, or 5 mils to 8 mils. The base coat may comprise a two or more layer system comprising an underlying layer (underlaying layer) and one or more overlying layers (overlaying layers). The topcoat, cured sealant layer, primer layer between the photovoltaic cells and the electrical interconnects may have a dry (cured) film thickness in the range of 0.2 mil to 10 mil, or any subrange included therein, such as 1 mil to 2 mil, 0.5 mil to 5 mil, 2.5 mil to 7 mil, or 7 mil to 10 mil. Two or more basecoat coating systems comprising at least a topcoat and a basecoat may together have a dry (cured) film thickness in the range of 0.5 mils to 50 mils, or any subrange included therein, such as 1 mil to 10 mils, 10 mils to 40 mils, 25 mils to 35 mils, or 5 mils to 8 mils. Dry film thickness values were measured using a Marathon electronic digital micrometer C0030025.

It is contemplated that the coating methods described herein may use a coating composition that can be applied to all or at least a portion of a substrate and cured to form a coating or layer thereon (e.g., a topcoat, a primer coating, a tie layer, a clearcoat, etc.). The applied coating may then form a coating system over all or at least a portion of the substrate and cure, either individually as a single coating, or collectively as more than one coating, including a protective barrier over at least a portion of the substrate. One such coating may be formed from a liquid sealant that cures to form a transparent portion (transparent) or a solid coating (i.e., a liquid sealant material or transparent coating) on at least a portion of the substrate.

The bottom surface coating may provide an overcoat or protective and/or durable coating. The bottom side coating may include an outermost backing layer (backing layer) of the photovoltaic module according to the description in this specification. The primer coating can comprise a plurality of coating layers, wherein any one or more of the coating layers can individually comprise the same or different coating compositions. Photovoltaic modules can include a topcoat as the outermost backing layer of the photovoltaic module, unlike some photovoltaic module designs that rely on a laminable film and/or backsheet (such as glass, metal, etc.).

Photovoltaic Modules 100 and 200 may include an outermost electrical coating, as described in co-pending U.S. patent application No.14/484,803, Shao et al, "electrically coated Photovoltaic Modules and methods of Making Same," which is incorporated herein by reference.

The bottom surface coating 112 or 210, alone or in combination with a primer coating and/or other coating, may include a primer-topcoat system (not shown) that may be applied to coat the treated surface 110 or 208 of the sealing material 106 or 206 of the photovoltaic module 100 or 200 (shown in fig. 1). The primer-surfacer system can include one, two, or more coating layers, wherein any coating layer or layers can individually include the same or different coating compositions. Coating layers (e.g., primer coats, tie layers, topcoats, monocoats, etc.) used to make protective coating systems for photovoltaic modules can include inorganic particles in a coating composition and the resulting cured basecoat. As used herein, a tie layer refers to an intermediate coating layer intended to promote or enhance adhesion between a primer coating (such as a primer coating or electrocoat) and an overlying primer coating.

The coating (e.g., the basecoat 112 and 206 and/or any underlying primer or tie layer) may include a particulate mineral material, such as mica, which may be added to a coating composition used to make a protective coating system for the photovoltaic module 100 or 200. The inorganic particles may include aluminum, silica (such as fumed silica), clay, pigments, and/or glass flakes, or any combination thereof. Inorganic particles may be added to the primer coat, tie coat, basecoat, topcoat, and/or monocoat, which may be applied to the photovoltaic cells 102 or 204 and the electrical interconnects 108 to coat and/or seal these components.

Protective coating systems comprising inorganic particles in a cured coating can exhibit improved barrier properties, such as lower water vapor transmission rates and/or lower permeation values. Inorganic particles, such as mica and other mineral particles, can improve the moisture barrier properties of polymeric films and coatings by increasing the tortuosity of the transmission path for water molecules to contact the film or coating. These improvements can be attributed to the relatively flat platelet-like structure of many inorganic particles. The inorganic particles may comprise platelet shapes and include an aspect ratio (defined as the ratio of the average width dimension of the particle to the average thickness dimension of the particle) ranging from 5 to 100 microns, or any subrange included therein. The inorganic particles may have an average particle size ranging from 10 to 40 microns, or any subrange included therein. Inorganic particle sizes are readily available from commercial suppliers. For example, are contained inParticle size of R-900 Titanium dioxide, inorganic particles containing Titanium dioxide pigment commercially available from DuPont Titanium Technologies, USA, is available through the product manual of DuPont found on the company website.

Inorganic particles may be added to the bottom coating to whiten/reflect the cured coating without altering the barrier properties of the bottom coating. For example, titanium dioxide (TiO) may be added₂) To whiten/reflect the cured floor coating without affecting the barrier properties of the cured floor coating.

Inorganic particles, such as mica, may be dispersed in the cured coating layer. The inorganic particles may be mechanically stirred and/or mixed into the coating composition or added after the slurry is formed. Surfactants may be used in the present invention. The inorganic particles may be mixed until fully dispersed in the cured coating layer (no settling).

Fig. 3 schematically illustrates a method 300 of manufacturing a photovoltaic module. The method 300 of manufacturing a photovoltaic module may include depositing (step 310) an encapsulant on at least a portion of a photovoltaic cell, curing (step 320) the encapsulant, treating (step 330) at least a portion of a surface of the cured encapsulant, depositing (step 340) a liquid coating composition on at least a portion of the treated encapsulant, and curing (step 350) the liquid coating composition to form a primer coating. The encapsulant can seal at least a portion of the photovoltaic cell. Treating the encapsulant may include treating at least a portion of a surface of the encapsulant with a corona discharge, a plasma, ultraviolet ozone, a plume discharge, a brush discharge, a glow discharge, or any combination thereof. After treating the cured sealing material, the method 300 of fig. 3 may further include depositing a primer on at least a portion of the treated sealing material; curing the primer and depositing a liquid coating composition on at least a portion of the cured primer.

Further, the method 300 can include depositing a silicone encapsulant on at least a portion of the photovoltaic cell, curing the silicone encapsulant, treating at least a portion of a surface of the cured silicone encapsulant with corona discharge, plasma, and/or ultraviolet ozone, depositing a liquid coating composition on at least a portion of the treated silicone encapsulant, and curing the liquid coating composition to form a primer coating. The method 300 further includes texturing at least a portion of a surface of the cured silicone sealant before, during, or after treating the cured silicone sealant with a corona discharge, plasma, and/or ultraviolet ozone.

The cured basecoat applied by the method 300 may comprise a polyurea resin. For example, the basecoat may include a cured layer formed from a liquid coating composition comprising a polyisocyanate, a polyamine, and a diamine chain extender. The liquid coating composition may include an amine-functional and/or a hydroxyl-functional silicone. The liquid coating composition may include an amine functional silicone (which is different from the polyamine) and/or a hydroxyl functional silicone. The liquid coating composition may include a fluoropolymer resin or a polyurea resin. For example, the liquid coating composition may include a polyurea resin formed from a coating composition comprising a polyisocyanate, a polyamine, a diamine chain extender, and an amine-functional and/or hydroxy-functional silicone, and curing the liquid coating composition to form the basecoat, the polyamine having the structure:

wherein the content of the first and second substances,

n is an integer from 2 to 4;

x represents an organic group having the valence of n, inert to isocyanate groups, such as an aliphatic residue; and

R¹and R²Represents an organic group inert to isocyanate groups.

It will be understood that, as used herein, the terms "disposed," "deposited," and their grammatical variants refer to the placement of a referenced component in spatial relationship to another component, where the components may be placed in direct physical contact or indirectly beside each other (with intervening components or spaces). Thus, and by way of example, where a first component is referred to as being disposed or deposited on, over, or covering a second component, it is to be understood that the first component can, but need not, be in direct physical contact with the second component. The terms "disposing" and "depositing" are used interchangeably, but the terms "disposing" and grammatical variations thereof may refer to the placement of a pre-existing component, such as a photovoltaic cell or a preformed sheet, while the terms "depositing" and grammatical variations thereof may refer to the in situ formation of the component, such as the application of a liquid coating or otherwise forming the component using chemical or physical deposition techniques.

The term "adjacent" as used herein describes the relative position of layers, coatings, films, sheets, photovoltaic cells, and other components comprising a photovoltaic module, wherein each component may be in direct physical contact or placed indirectly next to another component (with intervening components or spaces). Thus, and by way of example, a first component is said to be disposed adjacent a second component, it being understood that the first component may, but need not, be in direct physical contact with the second component.

It is contemplated that one coating or component may be disposed directly or indirectly next to another adjacent component or coating. In the present disclosure, where one component or coating is disposed indirectly beside another adjacent component or coating, it is contemplated that additional intervening layers, coatings, photovoltaic cells, etc., may be disposed between the two adjacent components. Thus, and by way of example, where a first coating may be said to be disposed adjacent a second coating, it is contemplated that the first coating may, but need not, be directly (directly) alongside and bonded to the second coating.

Similar elements of the photovoltaic module manufactured by the method 300 comprise substantially similar materials and perform substantially similar functions as those described above in connection with the corresponding elements of the photovoltaic modules 100 and 200 shown in fig. 1 and 2, respectively. For example, the photovoltaic cell, front side transparency, encapsulant, treated surface, and bottom side coating of the photovoltaic module manufactured by method 300 may comprise the same materials and perform the same functions as photovoltaic cell 102, front side transparency 106, encapsulant 106, treated surface 110, and bottom side coating 112, respectively, of photovoltaic module 100 of fig. 1. Similar to encapsulant layer 106 of photovoltaic module 100, the encapsulant layer of the photovoltaic module produced by method 300 may include a silicone encapsulant or a cured transparent liquid encapsulant. The photovoltaic module produced by the method 300 can include a photovoltaic cell comprising a crystalline silicon wafer. The photovoltaic module produced by method 300 may include photovoltaic cells including thin film photovoltaic cells.

Depositing the primer coating (see step 320) can include spraying the liquid coating composition to form the primer coating on the surface of the treated sealant opposite the front side transparency. As described above with respect to the bottom surface coatings 112 and 210, the bottom surface coating of the photovoltaic module produced by the method 300 may be deposited over all or a portion of the treated encapsulant material (forming a layer on the photovoltaic cell) using a suitable application technique (e.g., spray coating, dip coating, roll coating, brush coating, roll coating, curtain coating, flow coating, slot extrusion coating, and the like, as well as any combination thereof) to form a coating or layer (e.g., a topcoat, a primer coating, a tie layer, a clear coating, and the like) thereon.

Accordingly, the present disclosure is directed to, inter alia, the following non-limiting inventions: in a first method, method 1, the present disclosure provides a method of making a photovoltaic module comprising depositing an encapsulant over at least a portion of a photovoltaic cell, curing the encapsulant, treating at least a portion of the cured encapsulant, depositing a liquid coating composition over at least a portion of the treated encapsulant, and curing the liquid coating composition to form a primer coating.

In another approach, method 2, the present disclosure provides a method of making a photovoltaic module as provided in method 1, wherein the sealing material comprises a silicone sealant.

In another method, method 3, the present disclosure provides a method of making a photovoltaic module as provided in method 1 or method 2, wherein treating comprises treating at least a portion of the cured encapsulant surface with corona discharge, plasma, ultraviolet ozone, plume discharge, brush discharge, glow discharge, texturing process, or any combination thereof.

In another approach, method 4, the present disclosure provides a method of making a photovoltaic module as provided in any of methods 1-3, wherein treating comprises treating at least a portion of a surface of the cured encapsulant material opposable to the front transparency with corona discharge, plasma, ultraviolet ozone, plume discharge, brush discharge, glow discharge, luminescent discharge, or any combination thereof.

In another method, method 5, the present disclosure provides a method of making a photovoltaic module as provided in any of methods 1-4, further comprising texturing at least a portion of a surface of the cured encapsulant before or after treating the cured encapsulant with corona discharge, plasma, and/or ultraviolet ozone.

In another approach, method 6, the present disclosure provides a method of making a photovoltaic module as provided in any of methods 1-5, wherein the liquid coating composition comprises a polyisocyanate, a polyamine, and a diamine chain extender.

In another approach, method 7, the present disclosure provides a method of making a photovoltaic module as provided in any of methods 1-6, wherein the liquid coating composition further comprises an amine-functional silicone and/or a hydroxyl-functional silicone different from the polyamine.

In another method, method 8, the present disclosure provides a method of making a photovoltaic module as provided in any one of methods 1-7, wherein the liquid coating composition comprises a fluoropolymer resin or a polyurea resin.

In another method, method 9, the present disclosure provides a method of making a photovoltaic module as provided in any of methods 1-8, further comprising, after treating the cured encapsulant, depositing a primer over at least a portion of the cured encapsulant, curing the primer; and depositing a liquid coating composition over at least a portion of the cured primer.

In another method, method 10, the present disclosure provides a method of making a photovoltaic module as provided in any one of methods 1-9, wherein the primer comprises a silicone.

In another method, method 11, the present disclosure provides a method of making a photovoltaic module as provided in any one of methods 1-10, wherein the primer comprises octamethyltrisiloxane.

In another approach, approach 12, the present disclosure provides a method of making a photovoltaic module as provided in any of approaches 1-11, wherein the photovoltaic cell comprises a crystalline silicon wafer.

In another approach, method 13, the present disclosure provides a method of making a photovoltaic module as provided in any of methods 1-12, wherein the photovoltaic cell comprises a thin film photovoltaic cell adhered directly to the front side transparency.

In another method, method 14, the present disclosure provides a method of making a photovoltaic module as provided in any one of methods 1-13, wherein the encapsulant comprises a flowable coating composition that can be cured to a transparent layer after deposition.

In another method, method 15, the present disclosure provides a method of making a photovoltaic module as provided in any one of methods 1-14, wherein the encapsulant further comprises an adhesion promoting additive.

In another method, method 16, the present disclosure provides a method of making a photovoltaic module as provided in any one of methods 1-15, wherein the sealing material comprises a silicone sealant and an additive comprising an isocyanate functional silicone, a hydroxyl functional silicone, an amine functional silicone, or any combination thereof.

In another method, method 17, the present disclosure provides a method of making a photovoltaic module comprising depositing a silicone encapsulant over at least a portion of a photovoltaic cell, curing the silicone encapsulant; treating the cured silicone sealant with corona discharge, plasma, and/or ultraviolet ozone to deposit a liquid coating composition over at least a portion of the treated silicone sealant, wherein the liquid coating composition comprises a polyurea resin and the liquid coating composition is cured to form a basecoat, the polyurea resin being formed from a coating composition comprising a polyisocyanate, a polyamine, a diamine chain extender, and an amine-functional and/or hydroxy-functional silicone, the polyamine having the structure:

wherein n is an integer from 2 to 4, X represents an organic group having the valence of n and being inert towards isocyanate groups, and R¹And R²Represents an organic group inert to isocyanate groups.

In a first photovoltaic module, module 1, the present disclosure provides a photovoltaic module comprising a front side transparency, a photovoltaic cell, a sealing material deposited on at least a portion of the photovoltaic cell, a treated surface of at least a portion of the sealing material, and a primer coating deposited on at least a portion of the treated surface of the sealing material.

In another photovoltaic module, module 2, the present disclosure provides the photovoltaic module as provided by module 1, wherein the treated surface of the sealing material comprises a surface of a cured layer formed from the flowable coating composition, wherein at least a portion of the surface can be treated with corona discharge, plasma, ultraviolet ozone, plume discharge, brush discharge, glow discharge, or any combination thereof.

In another photovoltaic module, module 3, the present disclosure provides a photovoltaic module as provided in any one of modules 1 or 2, wherein the undercoat layer comprises a cured layer formed from a liquid coating composition comprising a polyisocyanate, a polyamine, and a diamine chain extender.

The invention has been described and illustrated in this specification to provide a thorough understanding of the structure, function, characteristics and use of the disclosed modules and processes. It is to be understood that the invention as described and illustrated in this specification is non-limiting and non-exhaustive. Accordingly, the disclosure is not limited by the description of the invention disclosed in this specification. The features and characteristics associated with the various embodiments of the invention may be combined with the features and characteristics of other embodiments of the invention. Such modifications and variations are intended to be included within the scope of this specification. Thus, the claims may be amended to recite features or characteristics expressly or inherently described herein, or otherwise expressly or inherently supported by the present specification. Further, the applicant reserves the right to amend the claims to affirmatively disclaim features and characteristics that may be present in the prior art. Thus, any such modifications comply with written description support requirements. The invention disclosed and described in this specification may comprise, consist of, or consist essentially of the structures and features as broadly described herein.

In the present specification, unless otherwise indicated, all numerical parameters are understood to be preceded and modified in all instances by the term "about" where the numerical parameter has the inherent variability characteristic of the underlying measurement technique used to determine the value of the parameter. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter described in this specification should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Also, any numerical range recited in this specification is intended to include all sub-ranges subsumed within the recited range with the same numerical precision. For example, a range of "1.0 to 10.0" is intended to include all sub-ranges between (and including) the recited minimum value of 1.0 and the recited maximum value of 10.0, that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Any maximum numerical limitation recited in this specification is intended to include all lower numerical limitations subsumed therein and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, applicants reserve the right to modify the specification, including the claims, to expressly recite any sub-ranges subsumed within the ranges expressly recited herein. It is intended in this specification to inherently describe all such ranges so that modifications to clearly recite any such subranges would comply with the written description support requirements.

The grammatical articles "a", "an" and "the", as used in this specification, are intended to include "at least one" or "one or more", unless otherwise specified. Thus, the articles are used in this specification to refer to one or to more than one (i.e., to "at least one") of the grammatical object of the article. For example, "a photovoltaic cell" means one or more photovoltaic cells, and thus, possibly, more than one photovoltaic cell is contemplated and employed or used in the practice of the described invention. Furthermore, the use of a singular noun includes the plural, and the use of a plural noun includes the singular, unless the context requires otherwise.

Any patent, publication, or other disclosure material, in its entirety, is herein incorporated by reference into the specification unless otherwise indicated, but is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this specification. As such, to the extent necessary, the explicit disclosure as set forth in this specification supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein is only incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. Applicants reserve the right to modify that specification to explicitly recite any subject matter or portion thereof, which is incorporated herein by reference.

The following non-limiting and non-exhaustive examples are intended to further illustrate the present invention, but not to limit the scope of the invention as described in this specification.

Examples

Example 1

Glass sheets comprising a protective coating system comprising a surface treated sealant material and a cured basecoat were evaluated. Glass sheets containing the protective coating system were compared to glass sheets containing a sealant material (without any surface treatment of the sealant material prior to deposition of the protective coating).

Cleaned with a washing solution of deionized water and isopropanol in a ratio of 1: 1Photovoltaic glass panels control and test glass panels were prepared.Photovoltaic glass is commercially available from PPG Industries, inc. By spraying a liquid thermosetting silicone material (DOW) on the back of each cleaned glass panelPV 6150, commercially available from Dow Corning Corporation, Midland, Michigan, USA) to make a glass sheet, covered with a glass sheet, and cured at 100 ℃ for 10 minutes to form a back side sealant layer.

The first control panel "a" was made by spraying polyurea resin formulation 1 (see table 1) directly on top of the untreated cured silicone sealant material. Polyurea resin formulation 1 was first cured at ambient temperature of 77 ° F (25 ℃) for 4-10 hours, and then cured at 140 ° F (60 ℃) for 24 hours to form the bottom coating of control panel a.

Test panel "B" was manufactured by: by DOW1200OS (octamethyltrisiloxane based primer commercially available from Dow Corning Corporation, Midland, Michigan, USA) spray-cured sealant material (as prepared and described in Panel A), dry the primer at ambient temperature of 77 deg.F (25 deg.C), and spray-deposit polyurea resin formulation 1 coating directly over the primer-coated and cured silicone sealant material. Curing the polyurea resin after depositionFormulation 1 (as described above for control plate a) to form the bottom surface coating of test plate B.

Test panel "C" was manufactured by treating the surface of a cured sealant material (as prepared and described in panel A) with a single pass of a hand-held corona discharge cell, BD-20AC Laboratory Corona treater (commercially available from Electro-technical Products, Chicago, Illinois, USA), supplied at a distance ranging from 1/8 inches (0.32cm) to 1 inch (2.54cm) from the instrument to the surface. Subsequently, the corona discharge treated surface of the sealant material was sprayed with polyurea resin formulation 1, which polyurea resin formulation 1 was sprayed directly onto the corona discharge treated and cured silicone sealant material. After deposition, polyurea resin formulation 1 (as described above for control panel a) was cured to form a bottom surface coating for test panel C.

The second control panel "D" was prepared by spraying directly on top of the untreated cured silicone sealing materialA fluoropolymer resin.Is a fluoropolymer resin commercially available from PPGIndustries, inc., Pittsburgh, pa., USA.The fluoropolymer resin coating was first cured at ambient temperature of 77F (25 c) for 4 to 10 hours and then cured at 140F (60 c) for a second time of 24 hours to form the bottom coating of control panel D.

Test board "E" passes through with DOW12000S (octamethyltrisiloxane based primer) spray cured sealant material (as prepared and described in panel D), dry the primer at ambient temperature of 77 deg.F (25 deg.C), and then seal in the primer coated and cured siliconeDirect spray deposition on materialsA fluoropolymer resin coating. After deposition, curing (as described above for control panel D)The fluoropolymer resin was coated to form the bottom surface coating of test panel E.

Test panel "F" was fabricated by treating the surface of the cured sealant material (as prepared and described in control panel D) with a single pass of a hand-held corona discharge cell (as described above for test panel C). Subsequently useThe fluoropolymer resin coating sprays the corona discharge treated surface of the sealant material, theThe fluoropolymer resin coating is sprayed directly onto the corona discharge treated and cured silicone sealant. Subsequently, use the above-mentioned forCuring conditions of fluoropolymer resin (see control panel D), curingThe fluoropolymer resin was coated to form the bottom surface coating of test panel F.

Polyurea resin basecoat formulation 1 (values in weight percent unless otherwise indicated) is provided in table 1.

TABLE 1

¹JEFFAMINE T5000 is a trifunctional polyoxypropylene primary diamine having a molecular weight of about 5000, available from Huntsman Corporation, The Woodlands, TX, USA.

²TEGO PROTECT 5000 is a hydroxy functional dimethylsiloxane available from Evonik Industrie AG, Essen, Germany.

³AEROSIL R805 is a fumed silica after treatment with octylsilane, available from Evonik industries AG, Essen, Germany.

⁴DESMOPHEN NH 1420 is a polyaspartic ester available from Bayer Materials Science LLC, Pittsburgh, Pa., USA.

⁵HXA CE 425 is an aliphatic diamine chain extender available from Hanson Group, LLC, Alpharetta, GA, USA.

⁶DABCO T-12 is dibutyltin dilaurate (DBTDL), available from Air Products and Chemicals, Inc., Allentown, Pa., USA.

⁷JEFFLINK754 is a cycloaliphatic isophorone-based secondary diamine available from huntsman corporation, The Woodlans, TX, USA.

⁸BYK-9077 is a wetting/dispersing agent, available from Altana AG, Wesel, Germany.

⁹TINUVIN 292 is a hindered amine UV stabilizer available from BASF, Ludwigshafen, Germany.

¹⁰BENTONE 34 is an organic derivative of a bentonite clay rheological additive, available from elementis specialties, inc., hightown, NJ, USA.

¹¹TI-PURE R-900 Titanium dioxide is a Titanium dioxide pigment available from DuPont Titanium Technologies, USA.

¹²PPG CAT 136 is an aliphatic polyisocyanate available from PPG Industries, Inc., Pittsburgh, PA, USA. PPG CAT 136(B) was mixed with the remaining ingredient (A) in Table 1 in a volume ratio of 1: 1.

As shown in fig. 4A and 4B, two control panels a and D, as well as test panels B, C, E and F surface-treated with sealing material, were tested according to IEC 61215: 2005 Standard test 10.13, damp Heat test was performed according to IEC 60068-2-78 (85. + -. 2 ℃ C., 85. + -. 3% relative humidity). The cross-hatch adhesion properties of the control and surface treated test panels were tested after 10 days of moist heat (DH) exposure using ScotchHigh-performance Masking Tape 232, commercially available from 3M co. The results of the damp heat/cross hatch adhesion test are provided in table 2. The Color change data was determined using a Macbeth Color-Eye spectrophotometer 2145, commercially available from X-Rite, Grand Rapids, Michigan, USA. The color change values given in table 2 are the change in the spectrophotometer reading or the value of "Δ E" after 10 days of moist heat exposure test.

TABLE 2

Figures 4A to 4F show the observation (observation) and cross-hatch adhesion test results for the control and test panels before and after 10 days of damp heat exposure.

Fig. 4A shows the back side of control panel a coated with a polyurea resin basecoat, shown before and after 10 days of wet heat exposure, after the cross-hatch adhesion test. As shown in fig. 4A, the initial cross-hatch adhesion test and visual inspection of control panel a showed a small amount of delamination to the bottom coating of polyurea resin formulation 1 at time zero, prior to exposure to the damp heat test. After 10 days of wet heat exposure and cross-hatch adhesion testing, visual inspection showed substantial delamination and peeling of the bottom coating from the sealant material of polyurea resin formulation 1.

FIG. 4B shows DOW adhesion after cross hatch adhesion testing, shown before and after 10 days of wet heat exposure1200OS primer and polyurea resin basecoat coated the backside of test panel B. Initial cross-hatch adhesion testing and visual inspection of the test panel B of fig. 4B prior to wet heat exposure revealed moderate amounts of delamination and peeling of the polyurea resin formulation 1 primer coating from the sealant material. The primer-treated test panel B also showed delamination and peeling of the bottom coating of polyurea resin formulation 1 from the sealant material after 10 days of wet heat exposure.

Fig. 4C shows the back side of test panel C treated with corona discharge and polyurea resin primer coating after cross-hatch adhesion test shown before and after 10 days of wet heat exposure. Initial cross hatch adhesion testing and visual inspection of corona discharge treated test panel C, as compared to both control panel a and primer treated test panel B of fig. 4A and 4B, showed only a single point (spot) of release of the polyurea resin formulation 1 primer coating from the seal material (see just above the horizontal line) prior to wet heat exposure. Corona discharge treated test panel C also showed a single point of peeling from the seal material after 10 days of wet heat exposure.

FIG. 4D shows the cross-hatch adhesion test followed by the cross-hatch adhesion test shown before and after 10 days of wet heat exposureFluoropolymer resin bottom coat the backside of control panel D. As shown in FIG. 4D, initial visual inspection of control panel D before exposure to the damp heat test at time zero showedDelamination and peeling of the bottom coating from the encapsulant. Control panel D showed after 10 days of moist heat exposureIncreased delamination and peeling of the bottom coating from the encapsulant.

FIG. 4E shows DOW adhesion after cross hatch adhesion testing, shown before and after 10 days of damp heat exposure1200OS primer andfluoropolymer resin primer coat the back side of test panel E. Cross-hatch adhesion test results for test panel E before wet heat exposure showedBoth delamination and peeling of the bottom coating from the encapsulant. Primer treated test panel E also showed after 10 days of wet heat exposure and cross-hatch adhesion testingDelamination and peeling of the bottom coating from the encapsulant.

FIG. 4F shows corona discharge and cross hatch adhesion test followed by a cross hatch adhesion test shown before and after 10 days of wet heat exposureThe fluoropolymer resin bottom surface coating treated the backside of test panel F. Similar to the results shown for both control panel D and primer treated test panel E, cross-hatch adhesion test results for corona discharge treated test panel F show that, prior to wet heat exposure,delamination and peeling of the bottom coating from the encapsulant. However, the cross-hatch adhesion test results for corona discharge treated test panels F showed only a single point of peel after wet heat exposure.

In summary, the experimental results show that corona discharge surface treatment of the sealant material (see test panels C and F of fig. 4C and 4F, respectively) proved to be the most effective method of improving the adhesion of the bottom surface coating to the sealant material, even after 10 days of damp heat exposure. The use of a primer between the seal material and the bottom coating (see test panels B and E of fig. 4B and 4E, respectively) did not show a significant improvement in adhesion of the bottom coating formulation. However, the primer-coated surface treatment of the sealing material does improve the adhesion of the primer-coated bottom surface coating formulation after wet heat exposure.

Example 2

Adhesion of the bottom surface coating to the sealant surface was evaluated for samples comprising glass plates comprising a protective coating system comprising a well surface treated and cured backside sealant and a cured bottom surface coating.

Using a washing solution with a ratio of deionized water to isopropanol of 1: 1The photovoltaic glass panel is prepared for testing the panel. By depositing a liquid thermosetting silicone coating sealant material (DOW) on the back side of a glass test panelPV 6150) to manufacture two test panels. A layer of mesh fabric of mesh size No.80, commercially available from JoAnn fabric and Craft Stores, Hudson, Ohio, USA, was placed adjacent to the freshly deposited liquid sealant material. Subsequently, the fabric covered sealant material was cured at 100 ℃ for 10 minutes to form a backside sealant layer. After the curing process, the scrim is removed from the sealant material to provide a reticulated impression surface of the cured sealant material. The embossed surface of the sealant material of test panel "a" was spray coated with polyurea resin formulation 1 (see table 2), which polyurea resin formulation 1 was spray coated directly onto the surface textured and cured silicone sealant layer. Deposited polyureasResin coating formulation 1 was cured first at ambient temperature of 77 ° F (25 ℃) for 4-10 hours and then at 140 ° F (60 ℃) for 24 hours to form a bottom coating.

By spraying directly on the surface-imprinted and cured silicone sealant materialThe fluoropolymer resin was used to make a second test panel "B".The fluoropolymer resin coating was cured at ambient temperature of 77F (25 c) for 4-10 hours and at 140F (60 c) for an additional 24 hours to form the bottom coating of test panel B.

The adhesion quality of the cured basecoat of the test panel to the cured seal material was evaluated by visual inspection using a cross-hatch adhesion test with a ScotchHigh-performance Masking Tape 232 commercially available from 3M Corporation, st. Upon visual inspection, test panel a showed adhesion failure between the surface imprinted sealant material and the primer coating of polyurea resin formulation 1. In contrast, the test panel B showed upon visual inspectionLess than 20% delamination and delamination of the fluoropolymer resin primer from the surface textured seal material.

In summary, the experimental results show that the panels B were tested against the polyurea resin of formulation 1The fluoropolymer resin primer coating provides improved adhesion to the surface textured and cured silicone sealing material.

Example 3

Adhesion of the bottom surface coating to the sealant surface was evaluated for samples comprising a glass plate comprising a protective coating system comprising a cured backside sealant (untreated surface) and a cured bottom surface coating.

Cleaning with a cleaning solution having a ratio of ionized water to isopropyl alcohol of 1: 1The photovoltaic glass panel is prepared for testing the panel. By depositing a liquid thermosetting silicone coating sealant material (DOW) on the backside of the cleaned test panelPV 6150) manufacturing test panels. The sealant material was then cured at 100 ℃ for 10 minutes to form a backside sealant layer. By usingThe test panels were sprayed with a fluoropolymer resin that was sprayed directly onto the (untreated) surface of the cured silicone sealant.The fluoropolymer resin coating was first cured at ambient temperature of 77F (25 c) for 4-10 hours and then cured at 140F (60 c) for 24 hours to form the bottom coating of the test panel.

According to IEC 61215: 2005 Standard test 10.13, damp Heat test of test panels was performed according to IEC 60068-2-78 (85. + -. 2 ℃ C., 85. + -. 3% relative humidity). After 500 hours of moist heat (DH) exposure, cross-hatch adhesion characteristics were tested on moist heat test panels using ScotchHigh-Performance Masking Tape 232, commercially available from 3M co.

The adhesion quality of the cured base coat of the test panels to the cured sealing material was evaluated by visual inspection. Visual inspection of the test panels after 500 hours of moist heat exposure showedThe fluoropolymer resin basecoat did not delaminate from the encapsulant. However, cross-hatch adhesion test results for the test panels as evaluated before and after 500 hours of wet heat exposure all showAdhesion failure between the fluoropolymer resin primer coating and the seal material.

In summary, the experimental results show that,adhesion of the fluoropolymer resin primer to the untreated surface of the seal material passed (survivor) the curing process for visual inspection. However, the adhesion properties observed are not sufficient to pass the cross-hatch adhesion test. Furthermore, after 500 hours of moist heat exposure and cross-hatch adhesion test, no observation was observedImproved adhesion of the fluoropolymer resin primer to the untreated surface of the sealing material.

Example 4

Adhesion of the bottom surface coating to the sealant surface of a glass sheet comprising a protective coating system comprising a cured backside sealant (untreated surface) and a cured bottom surface coating was evaluated.

Cleaned using a washing solution having a ratio of deionized water to isopropyl alcohol of 1: 1Photovoltaic glass panels were prepared for testing.Photovoltaic glass commercially available from PPG Industries, inc., Pittsburgh, pa., USA. By depositing a liquid thermosetting silicone coating sealant material (DOW) on the back side of each cleaned glass test panelPV 6150) were fabricated and cured at 100 ℃ for 10 minutes to form a backside sealant layer. Subsequently, each test panel was tested with polyurea resin formulation 1 (see Table 1) orThe fluoropolymer resin was sprayed and cured (as described previously) to form the bottom surface coating of the test panel.

Polyurea resin formulation 1 was first cured at ambient temperature of 77 ° F (25 ℃) for 4-10 hours and then at 140 ° F (60 ℃) for 24 hours to form the bottom surface coating of the first test panel. Will be provided withThe fluoropolymer resin coating was cured at ambient temperature of 77F (25 c) for 4-10 hours and at 140F (60 c) for an additional 24 hours to form a bottom coating for the second test panel.

Visual inspection of the test panels during the post-cure process at 140 ° F (60 ℃) showed delamination blistering of the polyurea resin basecoat of both test panels. In each case, delamination and adhesion failure were found between the polyurea resin basecoat formulations 3 and 4 and the untreated surface of the cured sealant resin.

In summary, the experimental results show that the adhesion of the polyurea resin basecoat (i.e., formulations 3 and 4) and the untreated surface of the sealant material is not sufficient to withstand the curing process.

Example 5

Adhesion of the bottom surface coating to the sealant surface of a glass sheet comprising a protective coating system comprising a cured backside sealant (untreated surface) and a cured bottom surface coating was evaluated.

The adhesion characteristics between the sealing material of the test panel and the cured polyurea resin primer coating were evaluated. Cleaning with a 1: 1 ratio of deionized water to isopropyl alcoholPhotovoltaic glass panels were prepared for testing. By depositing a liquid thermosetting silicone coating sealant material (DOW) on the back side of each glass test panelPV 6150) coated the cleaned test panels. The coated test panels were cured at 100 ℃ for 10 minutes to form a backside sealant layer. Each test panel was then spray coated with polyurea resin coating code Q900GY481 commercially available from PPG Industries, inc. The polyurea resin coating code Q900GY 48130 was cured at 140 deg.F (60 deg.C) for 130 minutes.

During the spray coating process of the polyurea resin coating code Q900GY481 base coat, visual inspection of the test panel showed that it failed to provide sufficient adhesion to the surface of the sealant material to cover the surface of the sealant material with the polyurea resin coating code Q900GY481 base coat.

In summary, experimental results show that the sealant material (absent surface treatment) produces a surface in which the interfacial tension between the sealant material and the polyurea resin formulation is sufficiently high to prevent surface wettability and subsequent adhesion of the polyurea resin coating code Q900GY481 base coat to the surface of the sealant material.

It is to be understood, however, that this description is not intended to limit the invention disclosed, but it is intended to cover modifications within the spirit and scope of the present invention, as defined by the appended claims. This specification has been written with reference to the methods and photovoltaic modules of the present invention. Those skilled in the art will recognize, however, that many substitutions, modifications, or combinations of any of the disclosed inventions (or portions thereof) can be made within the scope of the description. Accordingly, it is contemplated and understood that this description supports additional methods and photovoltaic modules not explicitly listed herein. Such invention may be obtained, for example, by combining, modifying or recombining any of the disclosed steps, sequences of steps, components, elements, features, characteristics, limitations, and the like, of the invention described in this specification. In this manner, applicants reserve the right to modify the claims during prosecution to add features as variously described in the present specification, and such modifications comply with the requirements supported by the written specification.

Claims (20)

1. A method of making a photovoltaic module, comprising:

depositing an encapsulant over at least a portion of the photovoltaic cell;

curing the sealing material;

treating at least a portion of the surface of the cured sealing material;

depositing a liquid coating composition over at least a portion of the treated sealing material; and

curing the liquid coating composition to form a basecoat.

2. The method of claim 1, wherein the sealing material comprises a silicone sealant.

3. The method of claim 1, wherein treating comprises treating at least a portion of the surface of the cured sealing material with corona discharge, plasma, ultraviolet ozone, plume discharge, brush discharge, glow discharge, texturing process, or any combination thereof.

4. The method of claim 1, wherein treating comprises treating at least a portion of the surface of the cured sealing material opposite the front transparency with corona discharge, plasma, ultraviolet ozone, plume discharge, brush discharge, glow discharge, or any combination thereof.

5. The method of claim 1, further comprising texturing at least a portion of the surface of the cured encapsulant before or after treating the cured encapsulant with a corona discharge, plasma, and/or ultraviolet ozone.

6. The method of claim 1, wherein the liquid coating composition comprises:

a polyisocyanate;

a polyamine; and

diamine chain extenders.

7. The method of claim 6, wherein the liquid coating composition further comprises an amine-functional silicone and/or a hydroxyl-functional silicone different from the polyamine.

8. The method of claim 1, wherein the liquid coating composition comprises a fluoropolymer resin or a polyurea resin.

9. The method of claim 1, further comprising, after treating the cured encapsulant:

depositing a primer over at least a portion of the treated sealing material;

curing the primer; and

depositing a liquid coating composition over at least a portion of the cured primer.

10. The method of claim 9, wherein the primer comprises silicone.

11. The method of claim 9, wherein the primer comprises octamethyltrisiloxane.

12. The method of claim 1, wherein the photovoltaic cell comprises a crystalline silicon wafer.

13. The method of claim 1, wherein the photovoltaic cell comprises a thin film photovoltaic cell directly adhered to the front side transparency.

14. The method of claim 1, wherein the encapsulant comprises a flowable coating composition that is cured to a clear layer after deposition.

15. The method of claim 1, wherein the encapsulant further comprises an adhesion promoting additive.

16. The method of claim 1, wherein the sealing material comprises a silicone sealant and an additive comprising an isocyanate functional silane, a hydroxyl functional silane, an amine functional silane, or any combination thereof.

17. A method of making a photovoltaic module, comprising:

depositing a silicone encapsulant over at least a portion of the photovoltaic cell;

curing the silicone sealant;

treating at least a portion of the cured silicone sealant with corona discharge, plasma, and/or ultraviolet ozone;

depositing a liquid coating composition over at least a portion of the treated silicone sealant,

wherein the liquid coating composition comprises a polyurea resin formed from a coating composition comprising:

a polyisocyanate;

a polyamine having the structure:

wherein:

n is an integer from 2 to 4;

x represents an organic group having the valence of n, inert to isocyanate groups; and

R¹and R²Represents an organic group inert to isocyanate groups;

a diamine chain extender; and

an amine-functional and/or hydroxyl-functional silicone; and

curing the liquid coating composition to form a basecoat.

18. A photovoltaic module, comprising:

a front face transparency;

a photovoltaic cell;

an encapsulant material deposited on at least a portion of the photovoltaic cell;

a treated surface of at least a portion of the sealing material; and

a primer coating deposited on at least a portion of the treated surface of the sealing material.

19. The photovoltaic module of claim 18, wherein the treated surface of the encapsulant comprises a surface of a cured layer formed from the flowable coating composition, wherein at least a portion of the surface is treatable with corona discharge, plasma, ultraviolet ozone, plume discharge, brush discharge, glow discharge, or any combination thereof.

20. The photovoltaic module of claim 18, wherein the bottom coating comprises a cured layer formed from a liquid coating composition comprising:

a polyisocyanate;

a polyamine; and

diamine chain extenders.