Reflective grids and processes for photovoltaic module films

Abstract

The present disclosure provides a process. In one embodiment, the process includes providing an aqueous pigment-polyolefin dispersion (PP dispersion) and applying a grid pattern of the aqueous PP dispersion onto a back encapsulant film. The process includes drying the grid pattern into a grid layer to form a grid-like back encapsulant film. The process includes disposing a plurality of photovoltaic cells and a front encapsulant film onto the grid-like back encapsulant film to form a stack, and laminating the stack to form a reflective photovoltaic (PV) module. The present disclosure also provides a reflective photovoltaic module produced by the process.

Description

[Background technology]

[0001] Photovoltaic (PV) modules are characterized by their efficiency in converting incident solar energy into usable electricity. PV modules utilizing crystalline silicon photovoltaic cells achieve efficiencies of approximately 23.5% or higher.

[0002] A known method for increasing the efficiency of PV modules is to enhance light reflection by adding a reflective layer within the PV module. Conventional techniques for adding a reflective layer to a PV module include (i) melt bonding a reflective material to a encapsulant film, (ii) adding an additional structural layer such as a reflective backsheet to the PV module, and (i) and / or adding a bonding layer to achieve (ii). These conventional approaches impose complex properties and / or additional structural requirements on the PV module.

[0003] Furthermore, the PV module manufacturing process is time-consuming and cumbersome, and it is known that PV module manufacturing requires a highly energy-intensive and time-consuming lamination process. The lamination process is typically a bottleneck in the PV module manufacturing process. The aforementioned burden in the prior art for manufacturing the reflective layer does not mediate the problems in PV module manufacturing, but rather exacerbates the shortcomings of PV module manufacturing.

[0004] In this field, there is a recognized need for simplified techniques for adding reflective layers to PV modules that shorten PV manufacturing time, reduce PV module production energy, and lower PV module material costs. [Overview of the Initiative]

[0005] This disclosure provides a process. In one embodiment, the process includes providing an aqueous pigment-polyolefin dispersion (PP dispersion) and applying a grid pattern of the aqueous PP dispersion onto a back sealant film. This process includes drying the grid pattern to form a grid layer and creating a grid-like back sealant film.

[0006] This disclosure provides a photovoltaic (PV) module. In one embodiment, the PV module comprises a grid-like back sealant film, a front sealant film, and a plurality of photovoltaic cells sandwiched between the grid-like back sealant film and the front sealant film. The grid-like back sealant film has a surface and a grid layer adhered to the surface. The grid layer has (i) grid regions which are reflective material composed of polyolefin and pigment, and (ii) a plurality of land regions defined by the grid regions. Each land region does not contain reflective material. The PV module includes a plurality of photovoltaic cells, each photovoltaic cell arranged on its respective land region. [Brief explanation of the drawing]

[0007] [Figure 1] This is a top view of a grid layer of reflective material on the surface of a back sealing film according to one embodiment of the present disclosure. [Figure 2] This is an exploded elevation view of a stack having a grid-shaped back sealing film, a photovoltaic cell, and a front sealing film according to one embodiment of the present disclosure. [Figure 3] This is an elevation view of a reflective photovoltaic module and grid layer in direct contact with a front sealing film and a rear sealing film, according to one embodiment of the present disclosure. [Figure 4] This is an elevation view of a reflective photovoltaic module according to one embodiment of the present disclosure, having a grid layer that is in direct contact with a back sealing film but not in direct contact with a front sealing film.

[0008] definition Any references to the periodic table refer to the edition published by CRC Press, Inc., 1990–1991. References to element groups in this table are based on a new notation for numbering groups.

[0009] For the purposes of U.S. patent practice, any referenced patent, patent application, or publication is incorporated by reference in its entirety (or an equivalent U.S. version thereof) particularly with respect to definitional disclosures (to the extent that they do not conflict with any definitions specifically provided in this disclosure) and general knowledge in the art.

[0010] Numerical ranges disclosed herein include all values ​​from the lower limit to the upper limit, including the lower and upper limits. In the case of ranges containing explicit values ​​(e.g., 1 or 2, or 3 to 5, or 6 or 7), any sub-ranges between any two explicit values ​​are included (e.g., the above range of 1 to 7 includes 1 to 2, 2 to 6, 5 to 7, 3 to 7, 5 to 6, etc.).

[0011] Unless otherwise stated, implied by the context, or customary in the art, all parts and percentages are based on weight, and all test methods are current as of the filing date of this disclosure.

[0012] As used herein, the terms “blend” or “polymer blend” refer to a blend of two or more polymers. Such a blend may or may not be miscible (i.e., not phase-separated at the molecular level). Such a blend may or may not be phase-separated. Such a blend may or may not contain one or more domain configurations as determined by transmission electron spectroscopy, light scattering, X-ray scattering, and other methods well known in the art.

[0013] The term "composition" refers to a mixture of materials containing the composition, as well as reaction and decomposition products formed from the materials of the composition.

[0014] The terms "comprising", "including", "having", and their derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether or not specifically disclosed. To avoid doubt, all compositions claimed through the use of the term "comprising" may include any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless specifically stated to the contrary. In contrast, the term "consisting essentially of" excludes any other constituent components, steps, or procedures from the scope of any subsequent description, except for those that are not essential to the operation. The term "consisting of" excludes any constituent components, steps, or procedures not expressly depicted or enumerated. The term "or" refers to the listed members individually and in any combination, unless otherwise specified. The use of the singular form includes the use of the plural form, and vice versa.

[0015] Terms such as "elastomer" refer to rubber-like polymers that can be stretched to at least twice their original length and very rapidly contract to approximately their original length when the stretching force is released. Elastomers have a modulus of elasticity of about 10,000 psi (68.95 MPa) or less and, in an uncrosslinked state at room temperature using the method of ASTM D638-72, typically have an elongation of more than 200%.

[0016] Terms such as "ethylene elastomer" refer to elastomers composed of ethylene-based polymers.

[0017] "Ethylene polymer" is a polymer that contains more than 50 weight percent (wt%) of polymerized ethylene monomer (based on the total amount of polymerizable monomers) and may optionally contain at least one comonomer. Ethylene polymers include ethylene homopolymers and ethylene copolymers (meaning units derived from ethylene and one or more comonomers). The terms "ethylene polymer" and "polyethylene" may be used synonymously. Non-limiting examples of ethylene polymers (polyethylenes) include low density polyethylene (LDPE) and linear polyethylene. Non-limiting examples of linear polyethylene include linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), multi-component ethylene copolymers (EPE), ethylene / α-olefin multi-block copolymers (also known as olefin block copolymers (OBC)), substantially linear or linear plastomers / elastomers, and high density polyethylene (HDPE). Generally, polyethylene can be produced using heterogeneous catalyst systems such as Ziegler-Natta catalysts, Group 4 transition metals and metallocenes, non-metallocene metal centers, heteroaryls, heterovalent aryloxy ethers, phosphine imines, and other homogeneous catalyst systems containing ligand structures, and others, in a gas phase, fluid bed reactor, liquid phase slurry process reactor, or liquid phase solution process reactor. Combinations of heterogeneous catalysts and / or homogeneous catalysts can also be used in either a single reactor or dual reactor configuration.

[0018] "Ethylene plastomer / elastomer" is a polymer derived from units of ethylene and at least one C3-C 10These are substantially linear or linear ethylene / α-olefin copolymers containing a uniform short-chain branching distribution including units derived from α-olefin comonomers. The ethylene plastomers / elastomers have densities ranging from 0.870 g / cc to 0.917 g / cc. Non-limiting examples of ethylene plastomers / elastomers include AFFINITY® plastomers and elastomers (available from The Dow Chemical Company), EXACT® plastomers (available from ExxonMobil Chemical), Tafmer® (available from Mitsui), Nexlene® (available from SK Chemicals Co.), and Lucene® (available from LG Chem Ltd.).

[0019] "High-density polyethylene" (or "HDPE") is an ethylene homopolymer, or at least one C4-C 10 α-olefin comonomer or C 4- The HDPE is an ethylene / α-olefin copolymer containing C8α-olefin comonomer, having a density of 0.940 g / cc, or 0.945 g / cc, or 0.950 g / cc, or 0.953 g / cc to 0.955 g / cc, or 0.960 g / cc, or 0.965 g / cc, or 0.970 g / cc, or 0.975 g / cc, or 0.980 g / cc. The HDPE may be a unimodal copolymer or a multimodal copolymer. A "unimodal ethylene copolymer" is an ethylene / C4-C copolymer that has one distinct peak in gel permeation chromatography (GPC) showing the molecular weight distribution. 10 It is an α-olefin copolymer. A "multimodal ethylene copolymer" is an ethylene / C4-C copolymer that has at least two distinct peaks in the GPC showing the molecular weight distribution. 10These are α-olefin copolymers. Multimodal copolymers include those with two peaks (bimodal) and copolymers with two or more peaks. Non-limiting examples of HDPE include DOW® high-density polyethylene (HDPE) resin (commercially available from Dow Chemical Company), ELITE® reinforced polyethylene resin (commercially available from Dow Chemical Company), CONTINUUM® bimodal polyethylene resin (commercially available from Dow Chemical Company), LUPOLEN® (commercially available from LyondellBasell), and HDPE products from Borealis, Ineos, and ExxonMobil.

[0020] "Low-density polyethylene" (or "LDPE") is an ethylene homopolymer, or at least one C3-C 10 LDPE consists of ethylene / α-olefin copolymers containing α-olefins, has a density of less than 0.915 g / cc to 0.940 g / cc, and contains long-chain branches with a broad MWD. ​​LDPE is typically produced by high-pressure free-radical polymerization (tubular reactor or autoclave using free-radical initiators). Non-limiting examples of LDPE include MarFlex® (Chevron Phillips), LUPOLEN® (LyondellBasell), and LDPE products from Borealis, Ineos, ExxonMobil, and others.

[0021] Linear low-density polyethylene (or "LLDPE") is a unit derived from ethylene and at least one C3-C 10LLDPE is a linear ethylene / α-olefin copolymer containing a heterogeneous short-chain branching distribution with units derived from α-olefin comonomers. In contrast to conventional LDPE, LLDPE is characterized by the presence of only a few, if any, long-chain branches. LLDPE has a density of less than 0.910 g / cc to 0.940 g / cc. Non-limiting examples of LLDPE include TUFLIN® linear low-density polyethylene resin (available from The Dow Chemical Company), DOWLEX® polyethylene resin (available from the Dow Chemical Company), and MARLEX® polyethylene (available from Chevron Phillips).

[0022] An "olefin polymer" or "polyolefin" is a polymer containing more than 50 weight percent of polymerizable olefin monomers (based on the total amount of polymerizable monomers), and may optionally contain at least one comonomer. Non-limiting examples of olefin polymers include ethylene polymers and propylene polymers.

[0023] A “polymer” is a compound prepared by polymerizing monomers that provide multiple and / or repeating “units” or “mer units” that constitute a polymer in polymeric form, whether of the same or different types. Therefore, the general term polymer encompasses both the term homopolymer, commonly used to refer to polymers prepared from only one type of monomer, and the term copolymer, commonly used to refer to polymers prepared from at least two types of monomers. It also encompasses all forms of copolymers, such as random, block, etc. The terms “ethylene / α-olefin polymer” and “propylene / α-olefin polymer” refer to the aforementioned copolymers prepared by polymerizing ethylene or propylene with one or more additional polymerizable α-olefin monomers, respectively. While polymers are often described as “made from” one or more specific monomers, “based on” a specific monomer or type of monomer, and “containing” a specific monomer content, etc., it should be noted that in this context, the term “monomer” is understood to refer to the polymerized residue of a specific monomer, and not to the non-polymerized species. In general, polymers as used herein refer to those based on "units," which are the polymerized forms of the corresponding monomers.

[0024] A “propylene polymer” is a polymer containing more than 50 weight percent of polymerizable propylene monomer (based on the total amount of polymerizable monomers) and may optionally contain at least one comonomer. Propylene polymers include propylene homopolymers and propylene copolymers (meaning units derived from propylene and one or more comonomers). The terms “propylene polymer” and “polypropylene” may be used interchangeably. Non-limiting examples of suitable propylene copolymers include propylene impact copolymers and propylene random copolymers.

[0025] "Ultra-low density polyethylene (or "ULDPE")" and "Very-low density polyethylene (or "VLDPE")" are each linear ethylene / α-olefin copolymers containing a heterogeneous short-chain branching distribution comprising units derived from ethylene and units derived from at least one C3-C 10 α-olefin comonomer. ULDPE and VLDPE each have a density of 0.885 g / cc to 0.915 g / cc. Non-limiting examples of ULDPE and VLDPE include ATTANE™ ultra-low density polyethylene resin (available from The Dow Chemical Company) and FLEXOMER™ very-low density polyethylene resin (available from The Dow Chemical Company).

[0026] Test Methods The average volume particle size refers to the volume average particle size measured using a Beckman LS230 Particle Size Analyzer, and the results are reported in micrometers (or microns).

[0027] The current-voltage (IV) characteristics of the PV module samples were evaluated using a pulsed sunlight simulator (Burger PS8 / PSS8) in accordance with the procedure described in IEC 60904. The light intensity was set to 1000 W / m 2 ². The equipment was calibrated using a standard module calibrated by CPVT. The short-circuit current (ISC), open-circuit voltage (VOC), fill factor (FF), and maximum power output (Pmax) are all parameters determined from the IV curve. The obtained Pmax was used as the initial power output of the PV module, and the results were reported in watts peak (W).

[0028] Density is measured in accordance with ASTM D792, Method B. The results are recorded in grams per cubic centimeter (g / cc).

[0029] Differential Scanning Calorimetry (DSC) Differential scanning calorimetry (DSC) can be used to measure the melting, crystallization, and glass transition behavior of polymers over a wide range of temperatures. For example, this analysis is performed using a TA Instruments Q1000 DSC equipped with a refrigerated cooling system (RCS) and autosampler. During the test, the nitrogen purge gas flow rate used is 50 mL / min. Each sample is melted and compressed into a thin film at approximately 175°C, and then the molten sample is air-cooled to room temperature (approximately 25°C). Test specimens of 3–10 mg, 6 mm in diameter are extracted from the cooled polymer, weighed, placed in a lightweight aluminum pan (approximately 50 mg), and pressed shut. The analysis is then performed to determine its thermal properties.

[0030] The thermal behavior of the sample is determined by raising and lowering the sample temperature to create a heat flow versus temperature profile. First, to remove its thermal history, the sample is rapidly heated to 180°C and held isothermally for 3 minutes. Next, the sample is cooled to -40°C at a cooling rate of 10°C / min and held isothermally at -40°C for 3 minutes. Then, the sample is heated to 180°C at a heating rate of 10°C / min (this is the "second heating" gradient). The cooling curve and the second heating curve are recorded. The cooling curve is analyzed by setting the baseline endpoint from the start of crystallization to -20°C. The thermal curve is analyzed by setting the baseline endpoint from -20°C to the end of melting. The values ​​to be determined are the extrapolated melting start point Tm and the extrapolated crystallization start point Tc. Heat of fusion (H f Crystallinity % of polyethylene samples is calculated using the following formula: (Joules / gram) and (H f ) / 292J / g)x100

[0031] From the second heating curve, the heat of fusion (H f The enthalpy of melting (also known as the peak melting temperature) and the peak melting temperature are reported.

[0032] The melting point Tm is first determined from the DSC heating curve by drawing a baseline between the start and end of the melting transition. Next, a tangent line is drawn to the lower temperature data of the melting peak. The point where this line intersects the baseline is the extrapolated melting start point (Tm). This is as described in Bernhard Wunderlich, The Basis of Thermal Analysis, in Thermal Characterization of Polymeric Materials 92, 277-278 (Edith A. Turi ed., 2d ed. 1997).

[0033] The glass transition temperature (Tg) is determined from the DSC heating curve, as described in Bernhard Wunderlich, *The Basis of Thermal Analysis, in Thermal Characterization of Polymeric Materials* 92, 278-279 (Edith A. Turi ed., 2d ed. 1997), where half of the sample has acquired the heat capacity of a liquid. Baselines are drawn below and above the glass transition region and extrapolated through the Tg region. The temperature at which the heat capacity of the sample is midway between these baselines is Tg.

[0034] The melt index (MI) (I2) is measured at g / 10 min using ASTM D1238 (190℃ / 2.16kg).

[0035] The melt flow rate (MFR) is measured at g / 10 min using ASTM D1238 (230℃ / 2.16kg). [Modes for carrying out the invention]

[0036] 1. Process This disclosure provides a process. In one embodiment, the process includes mixing an aqueous pigment dispersion with an aqueous polyolefin dispersion to form an aqueous pigment-polyolefin dispersion (PP dispersion). The process includes coating a grid pattern of the aqueous PP dispersion onto a back sealant film. The process includes drying the grid pattern to form a grid layer and creating a grid-like back sealant film.

[0037] In one embodiment, the process includes providing an aqueous polyolefin dispersion and providing an aqueous pigment dispersion. The process includes mixing the aqueous pigment dispersion with the aqueous polyolefin dispersion to form an aqueous pigment-polyolefin dispersion (PP dispersion).

[0038] The aqueous pigment dispersion is mixed with the aqueous polyolefin dispersion. As used herein, “aqueous polyolefin dispersion” is a dispersion comprising (i) water, (ii) one or more polyolefin particles (or “polyolefin particles”), (iii) one or more dispersants comprising carboxylic acids, carboxylic acid esters, and / or salts of at least one carboxylic acid, and (iv) the polyolefin particles having a volume average particle size of 0.1 to 5.0 microns, or 0.1 to 3.0 microns, or 0.1 to 2.0 microns, or 0.3 to 1.5 microns, or 0.5 to 1.4 microns.

[0039] Non-limiting examples of suitable polyolefins include propylene polymers (propylene / ethylene copolymer, propylene / C4-C8α-olefin copolymer), ethylene polymers, and ethylene / propylene / diene polymers (ethylene / propylene / ethylidene norbornene polymer (ENB)). Non-limiting examples of suitable ethylene polymers include ethylene elastomers, ethylene / C3-C8α-olefin copolymer, ethylene / C4-C8α-olefin copolymer, linear low-density polyethylene, ethylene / C4-C8α-olefin multiblock copolymer, functionalized ethylene polymers (maleic anhydride (MAH) ethylene polymers), and combinations thereof.

[0040] In one embodiment, the aqueous polyolefin dispersion comprises (i) water, (ii) ethylene polymer particles alone or in combination with propylene polymer particles, and (iii) long-chain C 12 -C 40 The material is composed of a dispersant selected from fatty acids, ethylene acrylic acid, sulfonates, and any combination thereof, and the ethylene polymer particles (either alone or in combination with propylene polymer particles) have a volume-average particle size of 0.1 to 5.0 microns, or 0.1 to 3.0 microns, or 0.1 to 2.0 microns, or 0.3 to 1.5 microns, or 0.3 to 1.5 microns, or 0.5 to 1.4 microns.

[0041] By selecting a dispersant, the following properties can be controlled or otherwise modified: (i) dispersed particle size, (ii) film formation properties, (iii) shear and storage stability, (iv) wetting properties (ability to flow onto the substrate without drawback or beading), and (v) adhesion to the substrate.

[0042] Aqueous polyolefin dispersions may be prepared by a continuous twin-screw extrusion process as described in U.S. Patent No. 8,318,257, No. 7,947,776, or No. 7,803,865. The mechanical dispersion technique includes a twin-screw extruder connected to a back pressure regulator, a melting pump, or a gear pump. A base reservoir and an initial water reservoir are also provided, each including a pump. Desired amounts of base and initial water are supplied from the base reservoir and the initial water reservoir. The polyolefin, i.e., an ethylene-based polymer resin or a propylene-based polymer resin and a dispersant, is fed into a twin-screw extruder (TSE) connected to a back pressure regulator at a back pressure of 1.5 MPa to 2.5 MPa, or 2.0 MPa. The ethylene-based polymer resin (or propylene-based polymer resin) and the dispersant are melted and blended, and then a potassium hydroxide (KOH) solution and a small amount of initial water are injected into the TSE at a temperature of 150°C and a screw rotation of 600 rpm. A high internal-phase emulsion (HIPE) is formed during this process and then diluted to 40% to 60% by weight before a back pressure valve. After the emulsion is cooled to below 100°C, the product is transferred to a container for recovering a dispersion of fine particles made of ethylene-based polymer resin or propylene-based resin.

[0043] In one embodiment, the fine particles are composed of a propylene / ethylene copolymer (and a dispersant). The propylene / ethylene copolymer has one, some, or all of the following properties: (i) a density of 0.850 g / cc to 0.9 g / cc, or 0.870 g / cc to 0.880 g / cc, and / or (ii) MFR of 6.0g / 10 min to 10.0g / 10 min, (iii) Particles having an average volume diameter of 0.1 micrometers to 2.0 micrometers

[0044] In one embodiment, the fine particles are composed of an ethylene / propylene / ENB terpolymer (and a dispersant). The ethylene / propylene / ENB terpolymer has one, some, or all of the following properties: (i) 65% to 75% by weight of ethylene and 4.0% to 6.0% by weight of ENB, and / or (ii) Mooney viscosity of 20 MU to 30 MU, and / or (iii) Particles having an average volume diameter of 0.1 to 2.0 microns, or 0.3 to 1.5 microns, or 0.5 to 1.4 microns.

[0045] In one embodiment, the fine particles are composed of an ethylene / octene multiblock copolymer (and a dispersant). The ethylene / octene multiblock copolymer (consisting only of ethylene and octene comonomers) has one, some, or all of the following properties: (i) Mw / Mn of 1.7-3.5 or 1.8-2.5, and / or (ii) Densities of 0.860 g / cc to 0.890 g / cc, or 0.870 g / cc or 0.880 g / cc, and / or (iii) Melting point of 118°C to 125°C, or 120°C to 123°C, Tm, and / or (iv) Melt index (MI) of 0.5g / 10 min to 10.0g / 10 min, or 1.0g / 10 min to 6g / 10 min, and (v) Particles having an average volume diameter of 0.1 to 2.0 microns, or 0.3 to 1.5 microns, or 0.5 to 1.4 microns.

[0046] In one embodiment, the fine particles are composed of an ethylene-based polymer (and a dispersant), which is an ethylene / octen copolymer. The ethylene / octen copolymer has one, some, or all of the following properties: (i) a density of 0.850 g / cc to 0.90 g / cc, or 0.860 g / cc to 0.880 g / cc, and / or (ii) MI of 2g / 10 min to 10g / 10 min, or 3g / 10 min to 7g / 10 min, (iii) Particles having an average volume diameter of 0.1 to 2.0 microns, or 0.3 to 1.5 microns, or 0.5 to 1.4 microns.

[0047] In one embodiment, the fine particles are composed of an MAH-functionalized ethylene / octen copolymer (and a dispersant). The MAH-functionalized ethylene / octen copolymer has one, some, or all of the following properties: (i) Density of 0.860 g / cc to 0.880 g / cc, and / or (ii) Melt index of 600g / 10 min to 700g / 10 min, or 630g / 10 min to 690g / 10 min, and / or (iii) MWDs 2.0 to 2.2, and (iv) Particles having an average volume diameter of 0.1 to 2.0 microns, or 0.3 to 1.5 microns, or 0.5 to 1.4 microns.

[0048] Aqueous pigment dispersions are formed by slurring one or more pigment particles with water. The pigment particles have an average volume diameter of 0.10 to 0.8 microns, or 0.2 to 0.7 microns, or 3.0 to 0.6 microns, or 0.4 to 0.5 microns. Non-limiting examples of suitable pigment particles include barium sulfate, zinc sulfide, barium lithopone, zinc phosphate, calcium carbonate, titanium dioxide (TiO2), zinc oxide (ZnO), silicon dioxide (SiO2), aluminum oxide (Al2O3), and combinations thereof.

[0049] In one embodiment, the pigment particles consist of titanium dioxide (TiO2). Non-limiting examples of suitable titanium dioxide particles include TI-PURE® R-104 TiO2, TI-PURE® R-105 TiO2, and TI-PURE® R-902, all available from Chemours ("Chemours").

[0050] In one embodiment, the process includes slurring pigment particles and a pigment dispersant in water.

[0051] In a further embodiment, the process includes slurring pigment particles using a pigment dispersant which is a sodium salt of maleic anhydride copolymer in water.

[0052] An aqueous pigment dispersion is mixed with an aqueous polyolefin dispersion to form an aqueous pigment-polyolefin dispersion (or "PP dispersion"). In the PP dispersion, solid particles (pigment particles, polyolefin particles) are uniformly suspended in a continuous aqueous phase. This process involves forming an aqueous polyolefin dispersion having a pH of less than 12. The aqueous polyolefin dispersion comprises (A) a dispersed polyolefin phase, (B) a dispersant, and (C) water, where the dispersed polyolefin phase has a volume-average particle size of 0.1 microns to 2.0 microns. The PP dispersion contains solids. "Solids" is the total weight of polyolefin fine particles, pigment particles, dispersant, and any pigment dispersant.

[0053] In one embodiment, the PP dispersion comprises, based on the total weight of solids, (i) 50% by weight, or 60% by weight, or 70% to 90% by weight, or 95% by weight of polyolefin fine particles; (ii) 5% by weight, or 10% to 15% by weight, or 20% by weight, or 40% by weight of pigment particles; (iii) 1% by weight, or 5% to 15% by weight, or 20% by weight of dispersant; and (iv) 0% by weight, or 0.05% to 2% by weight, or 5% by weight of pigment dispersant. It is understood that the polyolefin particles, dispersant, and any pigment dispersant constitute 100% by weight of the total weight of solids.

[0054] In one embodiment, the process includes compounding pigment particles into a polyolefin, and subsequently forming fine particles composed of the polyolefin and the pigment. The compounding step is performed before or during the formation of an aqueous polyolefin dispersion. The process includes forming an aqueous pigment-polyolefin dispersion having a pH of less than 12 and comprising (A) a dispersed polyolefin-pigment phase, (B) a dispersant, and (C) water. The dispersed pigment-polyolefin phase has a volume-average particle size of 0.1 to 2.0 microns, or 0.2 to 1.5 microns, or 0.3 to 1.4 microns.

[0055] This process involves coating a grid pattern of aqueous PP dispersion onto a back-sealing film. The back-sealing film is transparent and composed of an ethylene-based polymer. Non-limiting examples of ethylene-based polymers suitable for the back-sealing film include ethylene homopolymer, ethylene / C3-C8 copolymer, ethylene / C4-C8 copolymer, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene / diene interpolymer, ethylene / acrylic acid copolymer (EAA), ethylene-vinyl acetate copolymer (EVA), ethylene ethyl acrylate copolymer (EEA), ethylene methyl acrylate copolymer (EMA), ethylene n-butyl acrylate copolymer (eNBA), ethylene methacrylate copolymer (EMAA), and combinations thereof.

[0056] The grid pattern of the aqueous PP dispersion is applied to the back sealing film by screen printing, inkjet printing, roller printing, tampo printing, and pad printing.

[0057] In one embodiment, a grid pattern of aqueous PP dispersion is screen printed onto the surface of a back sealing film.

[0058] This process involves applying an aqueous PP dispersion to a back-sealing film 10, as shown in Figure 1. A grid pattern of the aqueous PP dispersion is applied to the surface of the back-sealing film 10. The grid pattern includes land regions and grid regions. The grid regions are boundaries around multiple land regions, and the grid regions completely surround and enclose each land region, defining multiple separate, closed land regions. Each land region does not contain the aqueous PP dispersion. As will be described later, the grid pattern becomes a grid layer 12, the grid pattern land regions become land regions 14 of the grid layer 12, and the grid pattern grid regions become grid regions 16 of the grid layer 12.

[0059] This process involves drying a back sealant film (having a grid pattern on it) to form a grid layer. The grid layer is formed from the grid pattern of the aqueous PP dispersion applied to the back sealant film. The grid layer is formed by drying the grid pattern. The back sealant film having the grid pattern is placed in an oven at a temperature of 40°C to 80°C for 1 to 60 minutes to remove water from the aqueous PP dispersion and dry the grid pattern. Once the water is removed, polyolefin particles and pigment particles remain. When the grid pattern is dried at a high temperature (40°C to 80°C), the polyolefin particles soften and coalesce, thereby forming a continuous or substantially continuous grid layer.

[0060] In Figure 1, the grid layer 12 has land regions 14 and grid regions 16 that are the same as, or substantially the same as, the grid pattern formed from the aqueous PP dispersion. The grid layer 12 includes grid regions 16 that are substantially continuous or continuous layers composed of polyolefin (and dispersant) particles and pigment particles from the aqueous PP dispersion, and the grid layer 12 is formed from the coalescence of polyolefin particles (from the aqueous dispersion) into a layer. The pigment particles (and pigment dispersant) are also uniformly dispersed throughout the fused polyolefin forming the grid layer 12. The land regions 14 do not contain polyolefin (dispersant) and do not contain pigment (and any pigment dispersant). As used herein, the term “grid back-sealing film” refers to a back-sealing film to which a grid layer is bonded, such as the back-sealing film 10 having the grid layer 12 (having land regions 14 and grid regions 16) shown in Figure 1.

[0061] In one embodiment, the grid layer 12 has a thickness of 1 mil to 10 mil, or 1 mil to 5 mil. The grid region 16 is composed of 50% to 90% by weight of polyolefin (0.5% to 5% by weight of dispersant) and 10% to 50% by weight of pigment, or 55% to 90% by weight of polyolefin and 45% to 10% by weight of pigment (and an optional pigment dispersant), based on the total weight of the grid layer.

[0062] This process involves arranging multiple PV cells and front sealing films on a grid-like back sealing film to form a stack. A “photovoltaic cell” (or “PV cell”) means a structure containing one or more photovoltaic cell effect materials of several inorganic or organic types. Non-limiting examples of photovoltaic effect materials include known photovoltaic effect materials, including crystalline silicon, polycrystalline silicon, amorphous silicon, copper indium gallium selenide (CIGS), copper indium selenide (CIS), cadmium telluride, gallium arsenide, dye-sensitized materials, and organic solar cell materials.

[0063] This process involves placing multiple photovoltaic cells 18 on each land region 14 of the back sealant film 10, as shown in Figure 2. The photovoltaic cells 18 are spaced apart on the land regions 14, so that when the back sealant film is viewed from above, grid regions 16 are visible between the photovoltaic cells 18. The front sealant film 20 is then placed on top of the multiple photovoltaic cells 18. The front sealant film 20 is placed on top of the back sealant film 10 so that the photovoltaic cells 18 are sandwiched between the back sealant film 10 and the front sealant film 20. The assembly (moving from bottom to top) includes the grid-like back sealant film 10, the photovoltaic cells 18, and the front sealant film 20, forming a "stack" as shown as stack 22 in Figure 2. The front sealing film 20 and the rear sealing film 10 are typically the same or substantially the same size and shape so that when the front sealing film 20 is placed on the rear sealing film 10 or otherwise superimposed (with the photovoltaic cell placed between them), the edges of the front sealing film 20 and the edges of the rear sealing film 10 form a common periphery for the stack 22.

[0064] The front sealing film is transparent and can be made from the same material as the back sealing film, or from a different material than the material in the back sealing film. In one embodiment, the front sealing film is made of an ethylene polymer. Non-limiting examples of suitable ethylene polymers include ethylene homopolymer, ethylene / C3-C8 copolymer, ethylene / C4-C8 copolymer, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene / diene interpolymer, ethylene / acrylic acid copolymer (EAA), ethylene-vinyl acetate copolymer (EVA), ethylene ethyl acrylate copolymer (EEA), ethylene methyl acrylate copolymer (EMA), ethylene n-butyl acrylate copolymer (eNBA), ethylene methacrylate copolymer (EMAA), and combinations thereof.

[0065] In one embodiment, the back sealing film 10 and the front sealing film 20 are each composed of polymer compositions individually selected from ethylene vinyl acetate copolymer (EVA), ethylene methyl methacrylate copolymer, ethylene methacrylate copolymer, propylene-based polymer, ethylene-based polymer, and combinations thereof.

[0066] This process involves stacking stacks to form a reflective photovoltaic module. The stacking step involves placing the stacks in a laminator. The laminator includes a heated metal platen facing into a vacuum chamber. The stacks are placed in the vacuum chamber. The vacuum chamber is closed and air is evacuated from the vacuum chamber. The metal platen applies sufficient heat and pressure to the stacks, resulting in the metal platen melting and, under vacuum, pressing the back sealant film onto the front sealant film to completely enclose and seal the photovoltaic cells 18 within the back sealant film 10 and the front sealant film 20.

[0067] In one embodiment, an additional structural layer can be added to the stack before the stack. A backsheet may be added under the back sealant film 10 or elsewhere. A bonding layer of adhesive material may be present between the backsheet and the back sealant film to facilitate adhesion between them. Opposing cover sheets, such as a front cover sheet placed on the front sealant film and a back cover sheet placed under the back sealant film 10, may be included in the laminated stack (either alone or in combination with the backsheet).

[0068] The process of the present invention is aqueous-based and, advantageously, avoids the need to melt or otherwise melt-bond the reflective layer onto the encapsulant film. The manufacturing process of the present invention is advantageous because it is minimal compared to conventional processes that require melting and extruding the reflective layer onto the encapsulant film. The manufacturing process is advantageous because it is simplified and minimal compared to conventional processes that require the addition of a reflective backsheet to the PV module.

[0069] 2. Photovoltaic Module This process provides a photovoltaic (PV) module. The PV module includes PV cells and is typically a laminated structure having at least one photoreactive surface that converts incident light into an electric current in outdoor applications. The PV module may also include a front cover sheet, a front sealant film, a rear sealant film, a back sheet, or a rear cover sheet, with the PV cells sandwiched between the front sealant film and the rear sealant film.

[0070] In one embodiment, a PV module is provided. The PV module comprises a grid-shaped back sealant film, a front sealant film, and a plurality of photovoltaic cells sandwiched between the back sealant film and the front sealant film. The grid-shaped back sealant film has a surface. The grid layer is adhered to the surface of the back sealant film. The grid layer has (i) grid regions which are reflective material composed of polyolefin and pigment, and (ii) a plurality of land regions defined by the grid regions, each land region which does not contain reflective material. The PV module includes a plurality of photovoltaic cells, each photovoltaic cell arranged on its respective land region. Thus, the PV module is a "reflective PV module".

[0071] In one embodiment, a PV module 24 is provided, as shown in Figure 3, which includes a front cover sheet 26, a front sealing film 20, a photovoltaic cell 18, a rear sealing film sheet, and a rear cover sheet 28. The PV cell 18 is surrounded or completely sealed by the rear sealing film 10 and the front sealing film 20. The front cover sheet 26 covers the front of the front sealing film 20 placed on the PV cell 18. The rear cover sheet 28 supports the back of the rear sealing film 10 placed on the back of the PV cell 18. The front cover sheet 26 and the rear cover sheet 28 are each made of glass, acrylic resin, or polycarbonate. In one embodiment, the front cover sheet 26 and the rear cover sheet 28 are each made of glass.

[0072] As shown in Figure 3, in the PV module 24, a portion of the front sealing film 20 is in direct contact with the PV cell 18, and another portion of the front sealing film 20 is in direct contact with the grid region 16. The term "direct contact" refers to a layer configuration in which the first layer is located directly adjacent to the second layer, and there are no intervening layers or structures between the first and second layers. A portion of the back sealing film 10 is also in direct contact with the back of the PV cell 18. In this way, the front sealing film 20 and the back sealing film 10 completely seal the PV cell 18. As shown in Figure 3, the front sealing film 20 is in direct contact with the front cover sheet 26, and the back sealing film 10 is in direct contact with the back cover sheet 28. The PV cell 18 is sandwiched between the front sealing film 20 and the back sealing film 10 so that both the front sealing film 20 and the back sealing film 10 are in direct contact with the PV cell 18. The front sealing film 20 and the back sealing film 10 are also in direct contact with the grid region 16.

[0073] In a PV module without a reflective grid layer, incident light strikes the gap between PV cells, passes through the front cover sheet, front sealant film, back sealant film, and back cover sheet, and finally exits the PV module without transferring light energy to the PV cells. As shown in Figure 3, the light ray 30 strikes the grid region 16 present in the gap between the PV cells 18. The light ray 30 is reflected by the polyolefin / pigment blend reflective material present in the grid region 16, and the light ray 30 returns through the front sealant film 20 and front cover sheet 26. A residual ray 32 is generated at the front sealant film-front cover sheet interface, and the residual ray 32 contacts the PV cells 18. The additional light effect on the PV cells 18 by the residual ray 32 improves, or otherwise increases, the conversion efficiency of the photovoltaic module 24 compared to the same PV module without a reflective layer.

[0074] In one embodiment, a PV module 34 is provided as shown in Figure 4. The PV module 34 includes a grid-like back sealant film 10 that is inverted or otherwise flipped over so that the grid layer 12 is positioned on the rearmost surface of the stack, as shown in Figure 4. In the PV module 34, the grid layer 12 is not in direct contact with the PV cells 18, nor is the grid layer 12 in direct contact with the front sealant film 20. Rather, the grid layer 12 is in direct contact with the back cover sheet 28 and the back sealant film 10. In the PV module 34, a portion of the front sealant film 20 is in direct contact with the PV cells 18, and another portion of the front sealant film 20 is in direct contact with the back sealant film 10. A portion of the back sealant film 10 is also in direct contact with the back of the PV cells 18. In this way, the front sealant film 20 and the back sealant film completely seal the PV cells 18. As shown in Figure 4, the front sealant film 20 is in direct contact with the front cover sheet 26, and the back sealant film 10 is in direct contact with the back cover sheet 28. The PV cell 18 is sandwiched between the front sealing film 20 and the back sealing film 10 such that both the front sealing film 20 and the back sealing film 10 are in direct contact with the PV cell 18.

[0075] As shown in Figure 4, the light ray 36 enters and strikes the grid region 16 present in the gap between the PV cells 18. The light ray 36 is reflected by the polyethylene / pigment blend reflective material present in the grid region 16 and returns through the back sealant film 10, the front sealant film 20, and the front cover sheet 26. A residual light ray 38 is generated at the front sealant film-front cover sheet interface and contacts the PV cells 18. The additional light effect on the PV cells 18 by the residual light ray 38 improves, or otherwise increases, the conversion efficiency of the photovoltaic module 34 compared to the same PV module without a reflective layer.

[0076] In one embodiment, the photovoltaic module is (A) Front cover sheet and (B) A front sealing film made of polymer material (selected from the following), (i) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min, and / or (ii) Ethylene polymer copolymers having a comonomer content of 10% to 40% by weight (based on the total weight of the copolymer) and an MI of 1 g / 10 min to 100 g / 10 min, selected from ethylene / vinyl acetate copolymer, ethylene / methyl acrylate copolymer, and ethylene / butyl acrylate copolymer. (C) Photovoltaic cell and, (D) A grid-shaped back sealing film, (i) A back sealing film made of polymer material (selected from the following), (a) Ethylene / C4-C8α-olefin having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min ィ Copolymers and / or (b) Ethylene polymer copolymers selected from ethylene / vinyl acetate copolymer, ethylene / methyl acrylate copolymer, and ethylene / butyl acrylate copolymer, having a comonomer content of 10% to 40% by weight (based on the total weight of the copolymer) and an MI of 1 g / 10 min to 100 g / 10 min. (ii) A grid-like back sealing film having a grid layer having grid regions composed of a blend of polyolefin, a dispersant, and titanium dioxide, (E) Back cover sheet and Equipped with, A photovoltaic module is a photovoltaic module with a Pmax / W value of 3W to 6W or 4.0W to 5.9W.

[0077] In one embodiment, the photovoltaic module is (A) Front cover sheet and (B) A front sealing film made of polymer material (selected from the following), (i) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (C) Photovoltaic cell and, (D) A grid-shaped back sealing film, (i) A back sealing film made of polymer material (selected from the following), (a) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (ii) A grid layer having a grid region composed of blends (select from below), (a) Propylene / ethylene copolymer, ethylene acrylic acid copolymer (dispersant), and titanium dioxide or (b) Ethylene / propylene / diene polymer and ethylene acrylic acid copolymer (dispersant), and titanium dioxide or (c) Ethylene / octene multiblock copolymer and ethylene acrylic acid copolymer (dispersant) or (d) Ethylene / octen copolymer and ethylene methacrylate copolymer (dispersant), and titanium dioxide or (e) MAH-functionalized ethylene / octen copolymer and C 18 -C 26 Carboxylic acid (dispersant), and titanium dioxide (E) Back cover sheet and Equipped with, A photovoltaic module characterized by having a Pmax / W value of 3W to 6W. In one embodiment, the PV module is a double-sided PV module and has a Pmax / W value of 5.0W to 5.5W, or greater than 5.0W to 5.3W.

[0078] In one embodiment, the photovoltaic module is (A) Front cover sheet and (B) A front sealing film made of polymer material (selected from the following), (i) an ethylene / C4-C8α-olefin copolymer (C) photovoltaic cell having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min, (D) A grid-shaped back sealing film, (i) A back sealing film made of polymer material (selected from the following), (a) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (ii) A grid-like back sealing film having a grid layer having grid regions composed of a blend selected from propylene / ethylene copolymer, ethylene acrylic acid copolymer (dispersant), and titanium dioxide, (E) Back cover sheet and Equipped with, A photovoltaic module characterized by having a Pmax / W value of 3W to 6W. In one embodiment, the PV module is a double-sided PV module and has a Pmax / W value of 5.0W to 5.5W, and greater than 5.0W to 5.3W.

[0079] In one embodiment, the photovoltaic module is (A) Front cover sheet and (B) A front sealing film made of polymer material (selected from the following), (i) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (C) Photovoltaic cell and, (D) A grid-shaped back sealing film, (i) A back sealing film made of polymer material (selected from the following), (a) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (ii) A grid-like back sealing film having a grid layer having grid regions composed of a blend selected from ethylene / propylene / diene polymer and ethylene acrylic acid copolymer (dispersant), and titanium dioxide, (E) Back cover sheet and Equipped with, A photovoltaic module characterized by having a Pmax / W value of 3W to 6W. In one embodiment, the PV module is a double-sided PV module and has a Pmax / W value of 5.0W to 5.5W, and greater than 5.0W to 5.3W.

[0080] In one embodiment, the photovoltaic module is (A) Front cover sheet and (B) A front sealing film made of polymer material (selected from the following), (i) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (C) Photovoltaic cell and, (D) A grid-shaped back sealing film, (i) A back sealing film made of polymer material (selected from the following), (a) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (ii) A grid-like back sealing film having a grid layer having grid regions composed of a blend selected from ethylene / octene multiblock copolymer and ethylene acrylic acid copolymer (dispersant) and titanium dioxide, (E) Back cover sheet and Equipped with, A photovoltaic module characterized by having a Pmax / W value of 3W to 6W. In one embodiment, the PV module is a double-sided PV module and has a Pmax / W value of 5.0W to 5.5W, and greater than 5.0W to 5.3W.

[0081] In one embodiment, the photovoltaic module is (A) Front cover sheet and (B) A front sealing film made of polymer material (selected from the following), (i) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (C) Photovoltaic cell and, (D) A grid-shaped back sealing film, (i) A back sealing film made of polymer material (selected from the following), (a) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (ii) A grid-like back sealing film having a grid layer having grid regions composed of a blend selected from ethylene / octen copolymer and ethylene methacrylate copolymer (dispersant), and titanium dioxide, (E) Back cover sheet and Equipped with, A photovoltaic module characterized by having a Pmax / W value of 3W to 6W. In one embodiment, the PV module is a double-sided PV module and has a Pmax / W value of 5.0W to 5.5W, and greater than 5.0W to 5.3W.

[0082] In one embodiment, the photovoltaic module is (A) Front cover sheet and (B) A front sealing film made of polymer material (selected from the following), (i) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (C) Photovoltaic cell and, (D) A grid-shaped back sealing film, (i) A back sealing film made of polymer material (selected from the following), (a) Ethylene / C4-C8α-olefin copolymer having a density of 0.850 g / cc to 0.900 g / cc and an MI of 1 g / 10 min to 100 g / 10 min (ii) MAH-functionalized ethylene / octen copolymer and C 18 -C 26 A grid-like back sealing film having a grid layer having grid regions composed of a blend selected from carboxylic acids (dispersants) and titanium dioxide, (E) Back cover sheet and Equipped with, A photovoltaic module characterized by having a Pmax / W value of 3W to 6W. In one embodiment, the PV module is a double-sided PV module and has a Pmax / W value of 5.0W to 5.5W, and greater than 5.0W to 5.3W.

[0083] Rather than being limiting, some embodiments of the present disclosure are described in detail below in the following examples. [Examples]

[0084] The materials used in the examples are provided in Tables 1A and 1B below.

[0085] [Table 1]

[0086] [Table 2]

[0087] Experimental procedure: 1. Preparation of aqueous polyolefin dispersion Dispersion A is a thermoplastic propylene / ethylene copolymer (Versify, manufactured by Dow Inc.). (商標)It is manufactured from 3200). Propylene / ethylene copolymer is dispersed in water by the extrusion process described in U.S. Patent No. 7,947,776. Ethylene acrylic acid copolymer (Primacor, manufactured by SK Chemical) neutralized with potassium hydroxide. (商標) 5980i) was used as a dispersant. The polymer-to-dispersant ratio was 85 / 15, and the final non-volatile content was 55%. The dispersed polymer phase, measured by a Coulter LS230 particle analyzer, had an average volume diameter of 0.86 microns.

[0088] Dispersion B is a thermoplastic ethylene / propylene / diene copolymer (Nordel, manufactured by Dow Inc.). (商標) It is manufactured from 4725P). Ethylene / propylene / diene polymer is dispersed in water by the extrusion process described in U.S. Patent No. 7,947,776. Ethylene acrylic acid copolymer (Primacor, manufactured by SK Chemical) neutralized with potassium hydroxide. (商標) 5980i) was used as a dispersant. The polymer-to-dispersant ratio was 80 / 20, and the final non-volatile content was 46%. The dispersed polymer phase, measured by a Coulter LS230 particle analyzer, had an average volume diameter of 1.24 microns.

[0089] Dispersion C is a thermoplastic ethylene / octene multiblock copolymer (INFUSE, manufactured by Dow Inc.). (商標) It is manufactured from 9500). The ethylene / octane multiblock copolymer was dispersed in water by the extrusion process described in U.S. Patent No. 7,947,776. As a dispersant, ethylene acrylic acid copolymer (Primacor, manufactured by SK Chemical) neutralized with dimethylethanolamine was used. (商標) 5980i) was used as a dispersant. The polymer-to-dispersant ratio was 80 / 20, and the final non-volatile content was 50%. The dispersed polymer phase, measured by a Coulter LS230 particle analyzer, had an average volume diameter of 0.56 microns.

[0090] Dispersion D is a thermoplastic ethylene / octen copolymer (ENGAGE, manufactured by Dow Inc.). (商標) Manufactured from 8200). Ethylene / octan copolymer dispersed in water by the extrusion process described in U.S. Patent No. 7,947,776. Potassium hydroxide neutralized ethylene methacrylate copolymer (Nucrel, manufactured by Dow Inc.) (商標) 960) and maleic anhydride grafted polyethylene wax (Clariant's Licoene (商標) 4351) was used as a dispersant. The polymer-to-dispersant ratio was 70 / 30, and the final non-volatile content was 44%. The dispersed polymer phase, measured by a Coulter LS230 particle analyzer, had an average volume diameter of 1.09 microns.

[0091] Dispersion E is a thermoplastic maleic anhydride grafted polyolefin elastomer (AFFINITY, manufactured by Dow Inc.). (商標) It is manufactured from 1000R). Maleic anhydride-grafted polyolefin elastomer was dispersed in water by the extrusion process described in U.S. Patent No. 7,947,776. C26 carboxylic acid (Unicid 350, Baker Hughes) neutralized with potassium hydroxide was used as a dispersant. The polymer-to-dispersant ratio was 95 / 5, and the final non-volatile content was 40%. The dispersed polymer phase, measured by a Coulter LS230 particle analyzer, had an average volume diameter of 0.21 microns.

[0092] 2. Preparation of aqueous pigment dispersion R902 slurry preparation method: Add 90 g of R902 TiO2 (volume average particle size = 0.42 microns, Chemours) and 1.2 g of Orotan 731A (sodium salt of maleic anhydride as a dispersant, Dow Inc.) to 60 g of water, and stir the mixture at 1000 RPM for 5 minutes to form a 60% TiO2 slurry, which is an aqueous pigment dispersion.

[0093] 3. Preparation of aqueous PP dispersion Examples of aqueous PP dispersions were formulated by mixing one of dispersions A, B, D, or E with an aqueous pigment dispersion (TiO2 slurry) at 1000 rpm for 5 minutes to form PP 1, PP 3, PP 5, and PP 6. Furthermore, aqueous PU dispersions were mixed with the aqueous pigment dispersion and dispersions A and C, respectively, at 1000 rpm for 5 minutes to form PP 2 and PP 4. The compositions of P-P1 to PP 6 are shown in Table 2 below. Detailed compositions can be found in Table 2.

[0094] [Table 3]

[0095] 4. Screen printing of the grid layer Next, the formulated aqueous PP dispersion was screen printed onto a back-sealing film, and then dried at 60°C for 20 minutes to form a grid-like back-sealing film.

[0096] 5. Manufacturing of PV modules The glass / glass bi-sided PV module used in this study was manufactured using the following procedure.

[0097] A 25cm x 25cm photovoltaic cell-embossed glass was washed with water and then dried before use. The base film used was a commercially available POE or EVA film with adhesion to glass (higher than 80 N / cm), high transparency (higher than 89%), and other properties required for commercially available PV encapsulant films. The POE and EVA base films were cut to fit the size of the photovoltaic cell-embossed glass. Then, the front glass / encapsulant film / soldered photovoltaic cell / grid pattern encapsulant film / back glass were laminated together in order to form a sandwich structure, and this was then edged with Scotch tape with a hole in the center.

[0098] Lamination was performed on a Shunhong SH-X-1000 laminator at 150°C for 20 minutes, including 4 minutes of vacuum processing and 16 minutes of pressing. The PV modules were then removed from the laminator and allowed to cool at room temperature.

[0099] The Pmax / W value was measured, and the results are shown in Table 3 below. The Pmax value is for standard test conditions, 1000 W / m². 2 Light and temperature were measured using a BERGER solar simulator at 25°C. Pmax / W was measured three times for each sample, and the average Pmax / W value is shown in Table 3 below.

[0100] [Table 4]

[0101] For two types of PERC two-sided cells, one type of single-sided PERC cell, and one type of N-Topcon cell, the power output of the PV module is improved by 0.14 to 0.22 W per PV module, and by the POE grid-like back sealing film of Examples 1 to 8 of the present invention, it is in the range of 2.42% to 4.56% per module.

[0102] This disclosure is not limited to the embodiments and examples contained herein, but is particularly intended to include some embodiments and modified forms of those embodiments, including combinations of elements of different embodiments, to the extent that they fall within the scope of the following claims. The present invention includes the following embodiments. [Aspect 1] It is a process, To provide an aqueous pigment-polyolefin dispersion (PP dispersion), The grid pattern of the aqueous PP dispersion is applied onto the back sealing film, A process comprising drying the grid pattern to form a grid layer and creating a grid-like back sealing film. [Aspect 2] To provide an aqueous polyolefin dispersion and an aqueous pigment dispersion, The process according to embodiment 1, comprising mixing the aqueous polyolefin dispersion with the aqueous pigment dispersion to form the aqueous pigment-polyolefin dispersion (PP dispersion). [Aspect 3] The process according to embodiment 2, comprising forming an aqueous polyolefin dispersion having a pH of less than 12, comprising (A) a dispersed polyolefin phase, (B) a dispersant, and (C) water, wherein the dispersed polyolefin phase has a volume average particle size of 0.1 microns to 2.0 microns. [Aspect 4] The method according to embodiment 2 or 3, comprising forming a slurry of pigment particles with a pigment dispersant and water to form the aqueous pigment dispersion. [Aspect 5] The provision described above means, The pigment particles are blended with the polyolefin, The process according to embodiment 1, comprising forming an aqueous pigment-polyolefin dispersion having a pH of less than 12, comprising (A) a dispersed polyolefin-pigment phase, (B) a dispersant, and (C) water, wherein the dispersed pigment-polyolefin phase has a volume average particle size of 0.1 microns to 2.0 microns. [Aspect 6] The coating process according to any one of embodiments 1 to 5, wherein the coating includes screen printing a grid pattern of the aqueous PP dispersion onto the back sealing film. [Aspect 7] The drying process described above is Forming a grid layer having multiple land regions and grid regions, The process according to any one of embodiments 1 to 6, further comprising forming the grid region as a continuous layer of the blend of the polyolefin and the pigment. [Aspect 8] The process according to embodiment 7, comprising arranging multiple photovoltaic cells on each of multiple land regions. [Aspect 9] In order to form a stack, a front sealing film is placed on the PV cell and the grid-shaped back sealing film, The process according to embodiment 8, comprising stacking the aforementioned stacks to form a reflective photovoltaic cell (PV) module. [Aspect 10] A photovoltaic module, The device comprises a grid-shaped back sealing film, a front sealing film, and a plurality of photovoltaic cells sandwiched between the grid-shaped back sealing film and the front sealing film. The grid-shaped back sealing film has a surface and a grid layer adhered to the surface, and the grid layer is (i) A grid region which is a reflective material composed of polyolefin and pigment, (ii) A plurality of land regions defined by the grid region, each land region having a plurality of land regions that do not contain the reflective material, A photovoltaic module comprising a plurality of photovoltaic cells, each photovoltaic cell located on its respective land region. [Aspect 11] The photovoltaic module according to embodiment 10, wherein the grid layer is in direct contact with a portion of the front sealing film. [Aspect 12] The photovoltaic module according to embodiment 10, wherein there is no direct contact between the grid layer and the front sealing film. [Aspect 13] The photovoltaic module according to any one of embodiments 10 to 12, wherein the grid region is a continuous layer adhered to the surface of the back sealing film. [Aspect 14] The photovoltaic module according to any one of embodiments 10 to 13, wherein the grid region is composed of a blend of polyolefin, pigment, and dispersant.

Claims

1. It is a process, To provide an aqueous polyolefin dispersion and an aqueous pigment dispersion, The aqueous polyolefin dispersion is mixed with the aqueous pigment dispersion to form an aqueous pigment-polyolefin dispersion, where the aqueous pigment-polyolefin dispersion is Polyolefins, Pigments, and The dispersant comprises a dispersant selected from the group consisting of carboxylic acids, carboxylic acid esters, and salts of carboxylic acids. The grid pattern of the aqueous pigment-polyolefin dispersion is applied to a back sealing film, The grid pattern is dried at 40-80°C to form a grid layer, thereby forming a grid-shaped back sealing film. Includes, The aforementioned drying process is Forming the grid layer having multiple land regions and grid regions, The grid region is formed as a continuous layer of the blend of the polyolefin and the pigment contained in the aqueous pigment-polyolefin dispersion. Includes, The land region does not contain the polyolefin and the pigment. The process further comprises arranging a plurality of photovoltaic (PV) cells on the plurality of land regions.

2. The process according to claim 1, comprising forming the aqueous pigment-polyolefin dispersion having a pH of less than 12, comprising (A) a dispersed polyolefin phase, (B) a dispersant, and (C) water, wherein the dispersed polyolefin phase has a volume average particle size of 0.1 μm to 2.0 μm.

3. The process according to claim 1 or 2, comprising slurring the pigment particles with a pigment dispersant and water to form the aqueous pigment-polyolefin dispersion.

4. The provision described above means, The pigment particles are blended with the polyolefin, The process according to claim 1, comprising forming an aqueous pigment-polyolefin dispersion having a pH of less than 12, comprising (A) a dispersed polyolefin-pigment phase, (B) a dispersant, and (C) water, wherein the dispersed polyolefin-pigment phase has a volume average particle size of 0.1 μm to 2.0 μm.

5. The process according to any one of claims 1 to 4, wherein the coating includes screen printing the grid pattern of the aqueous pigment-polyolefin dispersion onto the back sealing film.

6. In order to form a stack, the photovoltaic cell and the grid-shaped back sealing film are placed on top of the front sealing film, The process according to any one of claims 1 to 5, comprising stacking the aforementioned stacks to form a reflective photovoltaic (PV) module.

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