Resin composition for solar cell encapsulation material, solar cell encapsulation material, manufacturing process for solar cell encapsulation material and solar cell module

Abstract

Resin composition used to form a solar cell encapsulation material, wherein the resin composition comprises: an ionomer (A) of a copolymer based on ethylene and unsaturated carboxylic acids; and an ethylene-based epoxy group-containing copolymer (B), wherein the ionomer (A) of the ethylene-based copolymer based on unsaturated carboxylic acids contains two or more types of metal ions, and wherein, where a total amount of the resin composition for a solar cell encapsulation material is defined as 100% by mass, the content of the ethylene-based epoxy group-containing copolymer (B) is equal to or less than 5.0% by mass.

Description

TECHNICAL AREA

[0001] The present invention relates to a resin composition for a solar cell encapsulation material, a solar cell encapsulation material, a manufacturing process for a solar cell encapsulation material and a solar cell module. STATE OF THE ART

[0002] In recent years, the spread of photovoltaic power generation as a clean energy source has been promoted. Photovoltaic power generation converts solar energy directly into electrical energy using a semiconductor (solar cell element), such as a silicon cell. To ensure the long-term reliability of the solar cell element, it is sandwiched between encapsulating materials to protect it and prevent the ingress of foreign substances, moisture, or similar contaminants.

[0003] Solar cell encapsulation materials, which encapsulate solar cell elements, act as a protective material for these elements and must therefore exhibit creep resistance to prevent them from flowing easily, even when the module temperature rises due to sunlight. Furthermore, solar cell encapsulation materials must be highly transparent (light-transmitting) to prevent a decrease in the conversion efficiency of the solar cells. To protect solar cell module elements over a long period, solar cell encapsulation materials must also possess various properties, such as low moisture permeability, high volumetric resistance, heat resistance, weather resistance, and high adhesion.

[0004] Examples of techniques relating to such solar cell encapsulation materials include techniques described in Patent Document 1 (Japanese Unexamined Patent Publication No. 2014-95083) and Patent Document 2 (Japanese Unexamined Patent Publication No. 2013-177506).

[0005] Patent document 1 describes a resin film for encapsulating solar cells, comprising (A) at least one resin selected from an ethylene-vinyl acetate copolymer and a copolymer of ethylene and aliphatic unsaturated carboxylic acid, and (B) a thermoplastic resin other than resin (A) and a copolymer of ethylene and aliphatic unsaturated carboxylic acid ester, wherein resin (A) has a melt flow rate value of 0.3 g to 30 g and the resin film for encapsulating solar cells comprises an inner layer of resin (B) and a surface layer of resin (A) laminated onto the inner layer.

[0006] Patent document 2 describes a resin encapsulation film for a solar cell to which a resin is softened and attached, wherein the resin encapsulation film contains at least one ion-radiation crosslinking resin selected from the group consisting of an ethylene-vinyl acetate copolymer, a copolymer of ethylene and an aliphatic unsaturated carboxylic acid, and a copolymer of ethylene and an aliphatic unsaturated carboxylic acid ester, wherein the gel fraction is adjusted to 2 to 65 percent by mass by irradiating the ion-radiation crosslinking resin with ionizing radiation, and the heat shrinkage rate at 90 °C is equal to or less than 15 percent. ASSOCIATED DOCUMENT PATENT DOCUMENT [Patent Document 1] Japanese Unexamined Patent Publication No. 2014-95083 [Patent Document 2] Japanese Unexamined Patent Publication No. 2013-177506 BRIEF DESCRIPTION OF THE INVENTIONAL PROBLEM

[0007] The required technical standards for various properties of solar cell encapsulation materials are constantly increasing. The inventors of the present invention encountered the following problems regarding solar cell encapsulation materials that utilize a thermoplastic resin.

[0008] Firstly, solar cell encapsulation materials using a thermoplastic resin exhibit poor creep resistance at or above the melting point of the thermoplastic resin. It has been found that improving creep resistance by increasing the melting point of the thermoplastic resin can sometimes lead to a decrease in transparency. Therefore, the inventors of the present invention have found that conventional thermoplastic solar cell encapsulation materials are capable of being improved in a well-balanced way with regard to both transparency and creep resistance.

[0009] The present invention was made in view of the circumstances described above and provides a resin composition for a solar cell encapsulation material which enables the obtaining of a solar cell encapsulation material with an excellent performance balance of transparency and creep resistance. [Problem solving]

[0010] The inventors of the present invention repeatedly conducted intensive studies to solve the problems described above. As a result, the inventors of the present invention found that when an ionomer of a copolymer based on ethylene and unsaturated carboxylic acid, containing two or more types of metal ions, and an ethylene-based copolymer containing an epoxy group, are combined, it is possible to improve the trade-off relationship described above and to improve the transparency and creep resistance of the solar cell encapsulation materials to be obtained in a balanced manner, and thus made the present invention.

[0011] That is to say, according to the present invention, a resin composition for a solar cell encapsulation material, a solar cell encapsulation material, a manufacturing process for a solar cell encapsulation material and a solar cell module, which are described below, are provided. [1] Resin composition used to form a solar cell encapsulation material, the resin composition comprising: an ionomer (A) of a copolymer based on ethylene and unsaturated carboxylic acid and an epoxide group-containing copolymer based on ethylene (B), wherein the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid contains two or more types of metal ions. [2] Resin composition for a solar cell encapsulation material according to [1], wherein the metal ions forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid comprise two or more ions selected from the group consisting of a lithium ion, a potassium ion, a sodium ion, a silver ion, a copper ion, a calcium ion, a magnesium ion, a zinc ion, an aluminum ion, a barium ion, a beryllium ion, a strontium ion, a tin ion, a lead ion, an iron ion, a cobalt ion and a nickel ion. [3] Resin composition for a solar cell encapsulation material according to [1] or [2], wherein the metal ions forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid comprise a first metal ion and a second metal ion that differs from the first metal ion, the first metal ion comprises at least one metal ion selected from the group consisting of a sodium ion, a lithium ion, a potassium ion and a magnesium ion, and the second metal ion comprises at least one metal ion selected from the group consisting of a zinc ion, a copper ion, an iron ion, an aluminum ion, a silver ion, a cobalt ion and a nickel ion. [4] Resin composition for a solar cell encapsulation material according to [3], wherein in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid, the ratio of a value obtained by multiplying a mole number of the second metal ion by a valence to a value obtained by multiplying a mole number of the first metal ion by a valence is equal to or greater than 0.10 and equal to or less than 10.0. [5] Resin composition for a solar cell encapsulation material according to a [1] to [4], where, if the total amount of the resin composition for a solar cell encapsulation material is defined as 100% by mass, the content of the epoxy group-containing ethylene-based copolymer (B) is less than 10.0% by mass. [6] Resin composition for a solar cell encapsulation material according to [1] to [5], wherein the resin composition further comprises: a silane coupling agent (C). [7] Resin composition for a solar cell encapsulation material according to [6], wherein the silane coupling agent (C) comprises a silane coupling agent with an amino group. [8] Resin composition for a solar cell encapsulation material according to a [1] to [7], wherein the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid comprises an ionomer of a binary copolymer of ethylene and an unsaturated carboxylic acid (A1) and an ionomer of a ternary copolymer of ethylene, an unsaturated carboxylic acid and an unsaturated carboxylic acid ester (A2). [9] Resin composition for a solar cell encapsulation material according to a [1] to [8], wherein an unsaturated carboxylic acid forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid comprises at least one acid selected from an acrylic acid and a methacrylic acid.

[10] Resin composition for a solar cell encapsulation material according to one of [1] to [9], wherein the ethylene-based epoxy group containing copolymer (B) comprises at least one selected from an ethylene glycidyl(meth)acrylate copolymer, an ethylene glycidyl(meth)acrylate vinyl acetate copolymer and an ethylene glycidyl(meth)acrylate(meth)acrylate ester copolymer.

[11] Resin composition for a solar cell encapsulation material according to a [1] to

[10] , wherein in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid, where a total amount of the constituent units forming the copolymer based on ethylene and unsaturated carboxylic acid is defined as 100 wt%, a constituent unit derived from the unsaturated carboxylic acid is equal to or greater than 5 wt% and equal to or less than 35 wt%.

[12] Resin composition for a solar cell encapsulation material according to [1] to

[11] , wherein the degree of neutralization of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid is equal to or greater than 5% and equal to or less than 95%.

[13] Resin composition for a solar cell encapsulation material according to a [1] to

[12] , wherein at least part of a carboxyl group in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid and at least part of an epoxide group in the epoxide group-containing copolymer based on ethylene (B) react with each other to form a cross-linking structure.

[14] Resin composition for a solar cell encapsulation material according to a [1] to

[13] , where the turbidity measured according to the following procedure is less than 3.5%. (Procedure)

[0012] A 120 mm × 75 mm × 0.4 mm film is obtained, formed from the resin composition for a solar cell encapsulation material. This film is then sandwiched between 120 mm × 75 mm × 3.2 mm glass plates, held under vacuum in a vacuum laminator at 150 °C for 3 minutes, and pressed at 0.1 MPa (overpressure) for 5 minutes, resulting in laminated glass. The opacity of the laminated glass is then measured using an opacity meter according to JIS K 7136:2000.

[15] Resin composition for a solar cell encapsulation material according to a [1] to

[14] , where the adhesive strength on a glass plate, measured by the following method, is equal to or greater than 10 N / 15 mm. (Procedure)

[0013] A 120 mm × 75 mm × 0.4 mm film is obtained, formed from the resin composition for a solar cell encapsulation material. This film is then laminated onto the tin side of a 120 mm × 75 mm × 3.9 mm glass plate, held under vacuum in a vacuum laminator at 160 °C for 690 seconds, and pressed for 15 minutes at 0.06 MPa (overpressure), thus bonding the film to the tin side of the glass plate. The film is then peeled from the glass plate at a pulling speed of 100 mm / min and a peel angle of 180°, and the maximum stress is calculated as the bond strength (N / 15 mm) on the glass plate.

[16] Resin composition for a solar cell encapsulation material according to a [1] to

[15] , where a creepage distance measured according to the following procedure is less than 5 mm. (Procedure)

[0014] Films measuring 180 mm × 160 × 0.4 mm are obtained from the resin composition used for solar cell encapsulation. Two of these films are then laminated and sandwiched between 180 mm × 180 mm × 3.2 mm float glass panes with a displacement of 2 cm. The laminate is then vacuum-laminated at 150 °C for 3 minutes and pressed at 0.1 MPa (overpressure) for 5 minutes, resulting in a laminated glass unit. Finally, with one pane of the laminated glass unit fixed and the other freely displaceable, the displacement length of the glass is measured after 200 hours at 105 °C.

[17] Solar cell encapsulation material comprising a layer formed from the resin composition for a solar cell encapsulation material according to [1] to

[16] .

[18] Manufacturing process of a solar cell encapsulation material, wherein the process comprises a step of extruding the resin composition for a solar cell encapsulation material according to one of [1] to

[16] into a film form.

[19] Solar cell module, comprising: a solar cell element and an encapsulation resin layer formed from the solar cell encapsulation material according to

[17] for encapsulating the solar cell element. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0015] According to the present invention, it is possible to provide a resin composition for a solar cell encapsulation material that enables the obtaining of a solar cell encapsulation material with an excellent performance balance of transparency and creep resistance. List of characters Fig.Figure 1 is a cross-sectional view that schematically shows an example of the structure of a solar cell module of an embodiment according to the present invention. DESCRIPTION OF EXECUTION FORMS

[0016] An embodiment of the present invention is described below with reference to a drawing. The diagram is an outline diagram and does not correspond to the actual dimensional relationships. Unless expressly stated otherwise, the expression "X to Y" of a numerical range of values ​​represents a range equal to or greater than X and equal to or less than Y. Furthermore, the term (meth)acryl means acrylic or methacrylic. 1. Resin composition for solar cell encapsulation material

[0017] A resin composition for a solar cell encapsulation material according to the present embodiment (hereinafter also referred to as resin composition (P)) is a resin composition used to form a solar cell material, wherein the resin composition comprises an ionomer (A) of an ethylene-unsaturated carboxylic acid copolymer and an ethylene-based epoxy group-containing copolymer (B), wherein the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer comprises two or more types of metal ions.

[0018] According to studies conducted by the inventors of the present invention, it was found that attempts to improve the creep resistance of solar cell encapsulation materials using a thermoplastic resin can sometimes lead to a decrease in transparency. In other words, the inventors of the present invention have found that solar cell encapsulation materials using a thermoplastic resin are capable of being improved in a well-balanced manner with regard to both transparency and creep resistance.

[0019] The inventors of the present invention repeatedly conducted intensive studies to solve the problems described above. As a result, the inventors of the present invention found that when an ionomer (A) of a copolymer based on ethylene and unsaturated carboxylic acid, containing two or more types of metal ions, and an ethylene-based copolymer containing an epoxy group (B), it is possible to improve the trade-off relationship described above and to improve the transparency and creep resistance of the solar cell encapsulation materials to be obtained in a balanced manner.

[0020] That is, the resin composition (P) according to the present embodiment contains the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid, which contains two or more types of metal ions, and the epoxy group-containing ethylene-based copolymer (B), and is thereby able to improve the performance balance between the transparency and the creep resistance of the solar cell encapsulation materials to be obtained.

[0021] The reason for this is unclear, but the following reasons are conceivable.

[0022] Initially, since the resin composition (P) contains the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer and the epoxy-containing ethylene-based copolymer (B), at least some of the carboxyl groups in the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer and at least some of the epoxy groups in the epoxy-containing ethylene-based copolymer (B) react with each other in the solar cell encapsulation materials to be obtained, forming a cross-linked structure. This improves the mechanical properties and heat resistance of the solar cell encapsulation materials to be obtained. Consequently, the creep resistance of the solar cell encapsulation materials can be improved.

[0023] Furthermore, if the resin composition contains the ethylene-based epoxy group copolymer (B), a gel is likely to form in the solar cell encapsulation materials to be obtained due to the crosslinking reaction between the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer and the ethylene-based epoxy group copolymer (B). Therefore, the transparency or appearance of the solar cell encapsulation materials to be obtained is likely to deteriorate. However, since the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer contains two or more types of metal ions according to the present embodiment, it is possible to suppress an abrupt crosslinking reaction between the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer and the ethylene-based epoxy group copolymer (B) and to moderately promote the crosslinking reaction.This makes it possible to suppress the formation of a gel and, as a result, it is possible to improve the transparency and appearance of solar cell encapsulation materials.

[0024] For the reasons described above, it is assumed that the use of the resin composition for a solar cell encapsulation material according to the present embodiment enables the obtaining of a solar cell encapsulation material with an excellent performance balance of transparency and creep resistance.

[0025] In the resin composition (P) according to the present embodiment, the total content of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid and of the epoxy group-containing copolymer based on ethylene (B) is preferably equal to or greater than 60% by mass, more preferably equal to or greater than 70% by mass, even more preferably equal to or greater than 80% by mass and particularly preferably equal to or greater than 90% by mass, when the total amount of the resin composition (P) is defined as 100% by mass.If the total content of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid and the epoxy group-containing copolymer based on ethylene (B) is within the range described above, it is possible to further improve the balance of transparency, creep resistance, insulating properties, stiffness, water resistance, mechanical properties, heat resistance, handling and processability of the solar cell encapsulation materials to be obtained, as well as the PID resistance and the like of the solar cell modules to be obtained.

[0026] Each component that forms the resin composition (P) according to the present embodiment is described below. <Ionomer (A) eines Copolymers auf Basis von Ethylen und ungesättigter Carbonsäure>

[0027] The ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer according to the present embodiment is a resin in which at least some of the carboxyl groups in a polymer obtained by copolymerization of ethylene and at least one type of unsaturated carboxylic acid have been neutralized with metal ions. Examples of copolymers that can be used as ethylene-unsaturated carboxylic acid copolymers include a copolymer containing ethylene and an unsaturated carboxylic acid, a copolymer containing ethylene, an unsaturated carboxylic acid, and an ester of an unsaturated carboxylic acid, and the like.

[0028] Examples of the unsaturated carboxylic acid forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid according to the present embodiment include acrylic acid, methacrylic acid, 2-ethylacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, fumaric anhydride, itaconic anhydride, monomethyl maleate, monoethyl maleate and the like.

[0029] The unsaturated carboxylic acid preferably comprises at least one acid selected from acrylic acid and methacrylic acid with regard to productivity, hygiene, etc., of the ethylene-unsaturated carboxylic acid copolymer. These unsaturated carboxylic acids can be used individually, or two or more types can be used in combination. Furthermore, the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer can also be prepared by adding an ethylene-unsaturated carboxylic acid copolymer containing the unsaturated carboxylic acid described above, such as acrylic acid or methacrylic acid, as a constituent unit to one or more types of ionomers of an ethylene-unsaturated carboxylic acid copolymer.

[0030] When an ethylene-unsaturated carboxylic acid copolymer is added to an ionomer of an ethylene-unsaturated carboxylic acid copolymer containing two or more types of metal ions to produce the ionomer (A), it is possible to develop excellent adhesion and further improve the performance balance of transparency and water resistance, while advantageously maintaining the processability (film-forming properties) of the resin composition (P).

[0031] In the present embodiment, particularly preferred copolymers based on ethylene and unsaturated carboxylic acid are an ethylene-(meth)acrylic acid copolymer and an ethylene-(meth)acrylic acid-(meth)acrylic acid ester copolymer.

[0032] In the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid according to the present embodiment, if the total amount of the constituent units forming the copolymer based on ethylene and unsaturated carboxylic acid is defined as 100% by mass, the amount of a constituent unit derived from ethylene is preferably equal to or greater than 65% by mass and equal to or less than 95% by mass, and more preferably equal to or greater than 75% by mass and equal to or less than 92% by mass.

[0033] If the amount of the ethylene-derived constituent unit is equal to or greater than the lower limit, the heat resistance, mechanical strength, water resistance, processability, and similar properties of the resulting solar cell encapsulation materials can be further improved. Furthermore, if the amount of the ethylene-derived constituent unit is equal to or less than the upper limit, the transparency, flexibility, adhesion, and similar properties of the resulting solar cell encapsulation materials can be further improved.

[0034] In the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid according to the present embodiment, if the total amount of the constituent units forming the copolymer based on ethylene and unsaturated carboxylic acid is defined as 100% by mass, the amount of a constituent unit derived from an unsaturated carboxylic acid is preferably equal to or greater than 5% by mass and equal to or less than 35% by mass, and more preferably equal to or greater than 8% by mass and equal to or less than 25% by mass.

[0035] If the amount of the constituent unit derived from an unsaturated carboxylic acid is equal to or greater than the lower limit, the transparency, flexibility, adhesion, and other properties of the resulting solar cell encapsulation materials can be further improved. Furthermore, if the amount of the constituent unit derived from an unsaturated carboxylic acid is equal to or less than the upper limit, the heat resistance, mechanical strength, water resistance, processability, and other properties of the resulting solar cell encapsulation materials can be further improved.

[0036] In the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer according to the present embodiment, if the total amount of the constituent units forming the ethylene-unsaturated carboxylic acid copolymer is defined as 100% by weight, the amount of a constituent unit derived from other copolymerizable monomers is preferably equal to or greater than 0% by weight and equal to or less than 30% by weight, and more preferably equal to or greater than 0% by weight and equal to or less than 25% by weight. Examples of the other copolymerizable monomers include unsaturated esters, for example, vinyl esters such as vinyl acetate and vinyl propionate; unsaturated carboxylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, and 2-ethylhexyl methacrylate; and the like.If the constituent unit, which is derived from the other copolymerizable monomers, is contained in an amount within the range described above, the flexibility of the solar cell encapsulation materials to be obtained is improved, which is preferred.

[0037] Examples of the metal ions forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid according to the present embodiment include two or more ions selected from the group consisting of a lithium ion, a potassium ion, a sodium ion, a silver ion, a copper ion, a calcium ion, a magnesium ion, a zinc ion, an aluminum ion, a barium ion, a beryllium ion, a strontium ion, a tin ion, a lead ion, an iron ion, a cobalt ion and a nickel ion.

[0038] Furthermore, it is more preferred that the metal ions forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid according to the present embodiment comprise a first metal ion and a second metal ion that differs from the first metal ion, wherein the first metal ion comprises at least one metal ion selected from the group consisting of a sodium ion, a lithium ion, a potassium ion and a magnesium ion, and the second metal ion comprises at least one metal ion selected from the group consisting of a zinc ion, a copper ion, an iron ion, an aluminum ion, a silver ion, a cobalt ion and a nickel ion.

[0039] When both the first metal ion and the second metal ion are present, an abrupt crosslinking reaction between the ionomer (A) of the ethylene-unsaturated carboxylic acid-based copolymer and the ethylene-based epoxy group-containing copolymer (B) can be suppressed, thereby improving the processability of solar cell encapsulation materials and also suppressing the formation of a gel that develops in solar cell encapsulation films, and further improving the transparency and appearance of solar cell encapsulation materials.

[0040] In the resin composition (P) according to the present embodiment, if the metal ions forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid comprise the first metal ion and the second metal ion, the ratio of a value obtained by multiplying the number of moles of the second metal ion by its valence to a value obtained by multiplying the number of moles of the first metal ion by its valence ((number of moles of the second metal ion) × (valence of the second metal ion) / (number of moles of the first metal ion) × (valence of the first metal ion)) in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid is preferably equal to or greater than 0.10, more preferably equal to or greater than 0.15, and even more preferably equal to or greater than 0.20, with a view to further improving the balance of transparency and water resistance of the solar cell encapsulation materials to be obtained.

[0041] Furthermore, in the resin composition (P) according to the present embodiment, the ratio of the value obtained by multiplying the number of moles of the second metal ion by the valence to the value obtained by multiplying the number of moles of the first metal ion by the valence in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acids is preferably equal to or less than 10.0, more preferably equal to or less than 5.0, even more preferably equal to or less than 4.0, and even more preferably equal to or less than 3.0, and particularly preferably equal to or less than 2.5.

[0042] In the resin composition (P) according to the present embodiment, the ionomer (A) of the copolymer based on ethylene and an unsaturated carboxylic acid can be configured to include, for example, an ionomer 1 of a copolymer based on ethylene and an unsaturated carboxylic acid and an ionomer 2 of a copolymer based on ethylene and an unsaturated carboxylic acid that differs from ionomer 1.

[0043] This makes it possible, when the mixing ratio between ionomer 1 of the copolymer based on ethylene and an unsaturated carboxylic acid and ionomer 2 of the copolymer based on ethylene and an unsaturated carboxylic acid is adjusted, to easily adjust the ratio between the first metal ion and the second metal ion in ionomer (A) of the copolymer based on ethylene and an unsaturated carboxylic acid.

[0044] In the resin composition (P) according to the present embodiment, the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid preferably comprises, with a view to further improving the balance of flexibility, transparency and creep resistance of the solar cell encapsulation materials to be obtained, an ionomer (A1) of a binary copolymer of ethylene and an unsaturated carboxylic acid and an ionomer (A2) of a ternary copolymer of ethylene, an unsaturated carboxylic acid and an unsaturated carboxylic acid ester.

[0045] Furthermore, in the resin composition (P) according to the present embodiment, the content of the ionomer (A1) of the binary copolymer of ethylene and an unsaturated carboxylic acid is preferably equal to or greater than 40% by mass and equal to or less than 99% by mass, more preferably equal to or greater than 50% by mass and equal to or less than 95% by mass, and even more preferably equal to or greater than 60% by mass and equal to or less than 90% by mass, with a view to further improving the balance of flexibility, transparency and creep resistance of the solar cell encapsulation materials to be obtained.

[0046] In the resin composition (P) according to the present embodiment, the content of the ionomer (A2) of the ternary copolymer of ethylene, an unsaturated carboxylic acid and an unsaturated carboxylic acid ester is preferably equal to or greater than 1% by mass and equal to or less than 60% by mass, more preferably equal to or greater than 5% by mass and equal to or less than 50% by mass, and even more preferably equal to or greater than 10% by mass and equal to or less than 40% by mass, with a view to further improving the balance of flexibility, transparency and flexibility of the solar cell encapsulation materials to be obtained.

[0047] The content of the unsaturated carboxylic acid ester in the ionomer (A2) of the ternary copolymer of ethylene, an unsaturated carboxylic acid and an unsaturated carboxylic acid ester is preferably equal to or greater than 0 wt% and equal to or less than 30 wt%, more preferably equal to or greater than 1 wt% and equal to or less than 25 wt%, and even more preferably equal to or greater than 3 wt% and equal to or less than 20 wt%, when the total amount of the constituent units forming the copolymer based on ethylene and unsaturated carboxylic acid is defined as 100 wt%.

[0048] Examples of the unsaturated carboxylic acid ester in the ionomer (A2) of the ternary copolymer of ethylene, an unsaturated carboxylic acid, and an unsaturated carboxylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, and the like. At least one of these, selected from isobutyl methacrylate and n-butyl methacrylate, is preferred.

[0049] The degree of neutralization of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid according to the present embodiment is not particularly limited, but with a view to further improving the flexibility, adhesion, mechanical strength, processability and the like of the solar cell encapsulation materials to be obtained, it is preferably equal to or less than 95%, more preferably equal to or less than 90% and even more preferably equal to or less than 80%.

[0050] Furthermore, the degree of neutralization of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid according to the present embodiment is not particularly limited, but is preferably equal to or greater than 5%, more preferably equal to or greater than 10% and even more preferably equal to or greater than 15% with regard to the further improvement of the transparency, heat resistance, water resistance and the like of the solar cell encapsulation materials to be obtained.

[0051] Here, the degree of neutralization of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid refers to the percentage of carboxyl groups that are neutralized by the metal ions in all carboxyl groups contained in the copolymer based on ethylene and unsaturated carboxylic acid.

[0052] The manufacturing process for the ethylene-unsaturated carboxylic acid copolymer forming the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer according to the present embodiment is not particularly restricted, and the copolymer can be prepared by any known method. For example, the copolymer can be obtained by radical copolymerization of the individual polymerization components at high temperature and high pressure. Furthermore, the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer according to the present embodiment can be obtained by reacting the ethylene-unsaturated carboxylic acid copolymer with a metal compound. Alternatively, a commercially available ionomer can be used as the ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer.

[0053] In the present embodiment, the melt mass flow rate (MFR) of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid, measured according to JIS K 7210:1999 under conditions of 190 °C and a load of 2160 g, is preferably equal to or greater than 0.01 g / 10 minutes and equal to or less than 50 g / 10 minutes, more preferably equal to or greater than 0.1 g / 10 minutes and equal to or less than 30 g / 10 minutes, and particularly preferably equal to or greater than 0.1 g / 10 minutes and equal to or less than 19 g / 10 minutes. If the MFR is equal to or greater than the lower limit, the processability of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid can be further improved. If the MFR is equal to or less than the upper limit, the heat resistance, mechanical strength, and the like of the solar cell encapsulation materials to be obtained can be further improved.

[0054] The content of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid in the resin composition (P) according to the present embodiment is preferably equal to or greater than 50.0 wt% and equal to or less than 99.9 wt%, more preferably equal to or greater than 70.0 wt% and equal to or less than 99.5 wt%, even more preferably equal to or greater than 80.0 wt% and equal to or less than 99.5 wt%, and particularly preferably equal to or greater than 90.0 wt% and equal to or less than 99.0 wt% when the total amount of the resin composition (P) is defined as 100 wt%.If the content of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid is within the range described above, the performance balance of transparency, creep resistance, interlayer adhesion, insulating properties, stiffness and water resistance of solar cell encapsulation materials to be obtained, as well as the PID resistance and the like of solar cell modules to be obtained, can be further improved. <Epoxidgruppenhaltiges Copolymer auf Ethylenbasis (B)>

[0055] Examples of ethylene-based epoxy group-containing copolymers (B) include ethylene-based glycidyl group-containing copolymers.

[0056] Examples of ethylene-based copolymers containing glycidyl groups include at least one selected from an ethylene-glycidyl(meth)acrylate copolymer, an ethylene-glycidyl(meth)acrylate-vinyl acetate copolymer, an ethylene-glycidyl(meth)acrylate-(meth)acrylate ester copolymer, and the like.

[0057] The ethylene-based copolymer (B) containing an epoxide group can be obtained by copolymerization of a polymerizable group such as glycidyl (meth)acrylate, glycidyl vinyl ether, 1,2-epoxy-4-vinylcyclohexane, or 3,4-epoxycyclohexyl methyl methacrylate and a monomer bearing an epoxide group with ethylene. Alternatively, an epoxide group can be introduced into an ethylene-based copolymer by graft polymerization of a monomer with an epoxide group.

[0058] The proportion of a constituent unit derived from the monomer such as glycidyl(meth)acrylate in the ethylene-based epoxy group-containing copolymer (B) is preferably equal to or greater than 2% by mass and equal to or less than 30% by mass, more preferably equal to or greater than 3% by mass and equal to or less than 25% by mass, and even more preferably equal to or greater than 3% by mass and equal to or less than 15% by mass, when the total amount of constituent units forming the ethylene-based epoxy group-containing copolymer is defined as 100% by mass.

[0059] If the proportion of the constituent unit derived from the monomer, such as glycidyl methacrylate, is equal to or greater than the lower limit, the creep resistance of the resulting solar cell encapsulation materials and the interlayer adhesion of the solar cell modules will be improved, as will the transparency and flexibility of the solar cell encapsulation materials. Furthermore, if the proportion is equal to or less than the upper limit, the processability of the solar cell encapsulation materials will also improve.

[0060] “Glycidyl(meth)acrylate” stands for one or both of glycidyl methacrylate and glycidyl acrylate.

[0061] The “ethylene-based copolymer” in the epoxy-containing ethylene-based copolymer (B) means that an ethylene-derived constituent unit is the main component. Furthermore, the “main component” mentioned here means that the content of the “ethylene-derived constituent unit” is the highest among all constituent units. For example, in the case of a copolymer composed of constituent units derived from ethylene, glycidyl methacrylate, and vinyl acetate, the proportion of the ethylene-derived constituent units is greater than the proportion of either a glycidyl methacrylate-derived or a vinyl acetate-derived constituent unit.

[0062] The proportion of the “ethylene-derived constituent unit” in the ethylene-based epoxy group-containing copolymer (B) is preferably equal to or greater than 40% by weight, more preferably equal to or greater than 50% by weight, even more preferably equal to or greater than 55% by weight, and preferably equal to or less than 90% by weight, more preferably equal to or less than 80% by weight, and even more preferably equal to or less than 75% by weight, when the amount of all constituent units forming the ethylene-based epoxy group-containing copolymer is defined as 100% by weight. At this point, the ethylene-based epoxy group-containing copolymer may furthermore contain a monomer unit other than ethylene and the monomers with an epoxy group.

[0063] Examples of different monomers include vinyl esters, such as vinyl acetate and vinyl propionate; unsaturated carboxylic acid esters, such as acrylic esters, methacrylic esters, ethacrylic esters, crotonic esters, fumaric esters, maleic esters, maleic anhydride esters, itaconic esters, and itaconic anhydride esters; and the like. Examples of an ester group include alkyl ester groups with 1 to 12 carbon atoms, and in particular, alkyl ester groups such as methyl esters, ethyl esters, n-propyl esters, isopropyl esters, n-butyl esters, isobutyl esters, secondary butyl esters, 2-ethylhexyl esters, and isooctyl esters can be mentioned as examples.

[0064] Among these, at least one selected from vinyl acetate and (meth)acrylic acid ester is preferred.

[0065] In particular, in addition to copolymers comprising the ethylene-derived constituent unit and the glycidyl(meth)acrylate-derived constituent unit, copolymers are given as examples which, in addition to these two constituent units, contain at least one vinyl acetate-derived constituent unit and one (meth)acrylic acid ester-derived constituent unit.

[0066] The proportion of the constituent unit derived from a vinyl ester such as vinyl acetate and the constituent unit derived from an unsaturated carboxylic acid ester such as (meth)acrylic acid ester is preferably equal to or less than 40% by mass, and more preferably equal to or less than 30% by mass, when the total amount of all constituent units forming the ethylene-based epoxy group copolymer is defined as 100% by mass. In such a case, the moisture permeability of solar cell encapsulation materials decreases, and moisture resistance can be further improved.

[0067] The lower limit of the content of the constituent unit derived from the vinyl ester, such as vinyl acetate, and the constituent unit derived from the unsaturated carboxylic acid ester, such as (meth)acrylic acid ester, is not particularly limited, but is preferably equal to or greater than 5% by mass, more preferably equal to or greater than 10% by mass, and even more preferably equal to or greater than 15% by mass, when the amount of all constituent units forming the ethylene-based epoxy group copolymer is defined as 100% by mass.Furthermore, the proportion of the constituent unit derived from the vinyl ester, such as vinyl acetate, and the constituent unit derived from the unsaturated carboxylic acid ester, such as (meth)acrylic acid ester, is preferably in a range of 5 to 40 mass percent, more preferably in a range of 10 to 30 mass percent, and particularly preferably in a range of 15 to 30 mass percent.

[0068] As an ethylene-based epoxy group-containing copolymer (B), one type of copolymer can be used individually, or two or more types of copolymers with different copolymerization rates or the like can be used in combination.

[0069] The content of the ethylene-based epoxy group-containing copolymer (B) in the resin composition (P) according to the present embodiment is preferably less than 10.0 wt%, more preferably equal to or less than 5.0 wt%, and even more preferably equal to or less than 3.0 wt% when the total amount of the resin composition (P) is defined as 100 wt%. If the content of the ethylene-based epoxy group-containing copolymer (B) is within the range described above, the performance balance of creep resistance, transparency, adhesion, moisture resistance, insulating properties, flexibility, heat resistance, and processability of the resulting solar cell encapsulation materials can be further improved.

[0070] The lower limit of the content of the ethylene-based epoxy group-containing copolymer (B) in the resin composition (P) according to the present embodiment is not particularly restricted and may, for example, be equal to or greater than 0.1% by mass or may be equal to or greater than 0.5% by mass. <Silankupplungsmittel (C)>

[0071] The resin composition (P) according to the present embodiment preferably also includes a silane coupling agent (C) with a view to further improving the interlayer adhesion of the solar cell modules to be obtained.

[0072] Examples of the silane coupling agent (C) according to the present embodiment include silane coupling agents having a vinyl group, an amino group, or an epoxide group and a hydrolyzable group, such as an alkoxy group and the like. More specifically, examples include vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltriethoxysilane. These silane coupling agents (C) can be used individually, or two or more types of them can be used in combination.

[0073] Among these, with a view to further improving the interlayer adhesion of solar cell modules to be obtained, a silane coupling agent with an amino group, a silane coupling agent with a dimethoxy group and a silane coupling agent with a trimethoxy group are preferred, and a silane coupling agent with an amino group and a dimethoxy group is more preferred.

[0074] The reason for using a silane coupling agent with an amino group to further improve the interlayer adhesion of the solar cell modules to be obtained is not clear, but it is assumed that the amino group of the silane coupling agent is coordinated with a metal amino group in the copolymer based on ethylene and unsaturated carboxylic acid, thereby fixing the silane coupling agent to the copolymer based on ethylene and unsaturated carboxylic acid, and that an alkoxy group, which is another functional group in the silane coupling agent, reacts with a functional group on the surface of a base material such as glass, making it possible to obtain solar cell encapsulation materials with excellent adhesion to glass or the like.

[0075] Examples of the silane coupling agent with an amino group according to the present embodiment include N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminomethyl)-3-aminopropyltrimethoxysilane, N-(2-aminomethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminomethyl)-3-aminopropylmethyldiethoxysilane, N-(2-aminomethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, hydrochloride of N-(Vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, N-(2-aminomethyl)-8-aminooctyltrimethoxysilane, N-(2-aminoethyl)-8-aminooctyltrimethoxysilane, N-(2-aminomethyl)-8-Aminooctyltriethoxysilane and N-(2-Aminoethyl)-8-aminooctyltriethoxysilane.

[0076] In the resin composition (P) according to the present embodiment, the content of the silane coupling agent (C) is preferably equal to or greater than 0.001 mass percent and equal to or less than 5 mass percent, more preferably equal to or greater than 0.005 mass percent and equal to or less than 2 mass percent, and even more preferably equal to or greater than 0.01 mass percent and equal to or less than 1 mass percent, with a view to further improving the interlayer adhesion of the solar cell modules to be obtained.

[0077] In the resin composition (P) according to the present embodiment, the content of the silane coupling agent with an amino group is preferably equal to or greater than 30% by mass and equal to or less than 100% by mass, more preferably equal to or greater than 50% by mass and equal to or less than 100% by mass, and even more preferably equal to or greater than 70% by mass and equal to or less than 100% by mass, if the content of the silane coupling agent (C) in the resin composition (P) is defined as 100% by mass, with a view to further improving the interlayer adhesion of the solar cell modules to be obtained. <Andere Komponenten>

[0078] The resin composition (P) according to the present embodiment may contain components other than the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid, the epoxy group-containing ethylene-based copolymer (B), and the silane coupling agent (C), to an extent that does not impair the subject matter of the present invention. The other components are not particularly limited, and examples include a plasticizer, an oxidation inhibitor, a UV absorber, a wavelength conversion agent, an antistatic agent, a surfactant, a colorant, a photostable agent, a foaming agent, a lubricant, a crystal nucleation agent, a crystallization accelerator, a crystallization retarder, a catalyst deactivator, a heat radiation absorber, a heat radiation reflector, a heat dissipation agent, a thermoplastic resin, a thermosetting resin, and an inorganic filler.an organic filler, an impact strength enhancer, a lubricant, a crosslinking agent, a crosslinking aid, a tackifier, a processing aid, a mold release agent, a hydrolysis inhibitor, a heat resistance stabilizer, an antiblocking agent, an antifogging agent, a flame retardant, a flame-retardant aid, a light-diffusing agent, an antibacterial agent, an antifungal agent, a dispersant, and other resins. The other components can be used individually, or two or more types of them can be used in combination. <Trübung>

[0079] In the resin composition (P) according to the present embodiment, the turbidity measured by the following method is preferably less than 3.5% and more preferably less than 3.0%. If the turbidity is lower than the upper limit, it is possible to further improve the transparency of the solar cell encapsulation materials to be obtained.

[0080] To achieve such turbidity, the types of metal ions in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid, the types or proportions of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid and the epoxy group-containing ethylene-based copolymer (B) in the resin composition (P) according to the present embodiment and the like must be appropriately adjusted.

[0081] The lower limit of the turbidity of the resin composition (P) according to the present embodiment is not particularly limited and is, for example, equal to or greater than 0.01%. (Procedure)

[0082] A 120 mm × 75 mm × 0.4 mm film is obtained, formed from the resin composition (P) according to the present embodiment. The obtained film is then sandwiched between 120 mm × 75 mm × 3.2 mm glass plates, held under vacuum in a vacuum laminator at 150 °C for 3 minutes, and pressed at 0.1 MPa (overpressure) for 5 minutes, resulting in a laminated glass. The opacity of the resulting laminated glass is then measured using an opacity meter according to JIS K 7136: 2000. <kriechstrecke>

[0083] In the resin composition (P) according to the present embodiment, the creepage distance measured according to the following method is preferably less than 5 mm and more preferably equal to or less than 1 mm. If the creepage distance is equal to or less than the upper limit, it is possible to further improve the creep resistance of the solar cell encapsulation materials to be obtained.

[0084] To achieve such a creepage distance, the types of metal ions in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid, the types or proportions of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid and the epoxy group-containing ethylene-based copolymer (B) in the resin composition (P) according to the present embodiment and the like must be appropriately adjusted.

[0085] The lower limit of the creepage distance of the resin composition (P) according to the present embodiment is preferably 0 mm. (Procedure)

[0086] A film measuring 180 mm × 160 mm × 0.4 mm is obtained, formed from the resin composition (P) according to the present embodiment. Two of the obtained films are then laminated, sandwiched between 180 mm × 180 mm × 3.2 mm float glass panes with a displacement of 2 cm, held under vacuum in a vacuum laminator at 150 °C for 3 minutes, and pressed at 0.1 MPa (overpressure) for 5 minutes, thus obtaining a laminated glass. Then, with one pane of the resulting laminated glass fixed and the other pane freely displaceable, the displacement length of the glass is measured after 200 hours at 105 °C. <Haftfestigkeit an Glasplatte>

[0087] In the resin composition (P) according to the present embodiment, the adhesion strength to a glass plate, measured by the following method, is preferably equal to or greater than 10 N / 15 mm, more preferably equal to or greater than 20 N / 15 mm, and particularly preferably equal to or greater than 30 N / 15 mm. If the adhesion strength to a glass plate is equal to or greater than the lower limit, it is possible to further improve the interlayer adhesion of the solar cell modules to be obtained.

[0088] In order to achieve such an adhesive strength on a glass plate, the contents, types and the like of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid and the silane coupling agent (B) in the resin composition (P) must be appropriately adjusted according to the present embodiment. (Procedure)

[0089] A 120 mm × 75 mm × 0.4 mm film is obtained, formed from the resin composition (P) according to the present embodiment. The obtained film is then laminated onto one tin side of a 120 mm × 75 mm × 3.9 mm glass plate, held under vacuum in a vacuum laminator at 160 °C for 690 seconds, and pressed for 15 minutes at 0.06 MPa (overpressure), thereby bonding the film to the tin side of the glass plate. The film is then peeled from the glass plate at a pulling speed of 100 mm / min and a peel angle of 180°, and the maximum stress is calculated as the bond strength (N / 15 mm) on the glass plate. 2. Solar cell encapsulation materials

[0090] A solar cell encapsulation material according to the present embodiment comprises a layer formed from the resin composition (P) according to the present embodiment.

[0091] The solar cell encapsulation material according to the present embodiment can have a single-layer structure or a multi-layer structure consisting of two or more layers.

[0092] More precisely, the solar cell encapsulation material according to the present embodiment can be a film with a single-layer structure made from a layer formed from the resin composition (P) according to the present embodiment, can be a film with a multi-layer structure made from two or more layers formed from the resin composition (P) according to the present embodiment, or can be a film with a multi-layer structure with at least one layer formed from the resin composition (P) according to the present embodiment and at least one other layer than the layer formed from the resin composition (P) according to the present embodiment.

[0093] If the solar cell encapsulation material according to the present embodiment has a multi-layer structure, it is preferred that in a two-layer structure in which two outer layers (hereinafter also referred to as adhesive layers) are laminated, at least one of the outer layers is formed from the resin composition (P) according to the present embodiment, orin a three-layer structure in which an intermediate layer and two outer layers are provided, the latter being formed on their two surfaces such that the intermediate layer is sandwiched in place, at least one of the outer layers and the intermediate layer is formed from the resin composition (P) according to the present embodiment, wherein the three-layer structure described above is preferred with regard to achieving both transparency and adhesion, and wherein a three-layer structure in which the outer layers and the intermediate layer are formed from the resin composition (P) according to the present embodiment is particularly preferred.

[0094] In a film with a multilayer structure comprising a plurality of layers formed from the resin composition (P) according to the present embodiment, the compositions of the resin composition (P) according to the present embodiment or the types of ionomer contained in the individual layers (e.g., the copolymerization rate and degree of neutralization of the copolymer based on ethylene and unsaturated carboxylic acid, the types of metal ions, and the like) may be identical or different from one another.

[0095] The thickness of the solar cell encapsulation material according to the present embodiment is, for example, equal to or greater than 0.001 mm and equal to or less than 10 mm, preferably equal to or greater than 0.01 mm and equal to or less than 5 mm, and more preferably equal to or greater than 0.05 mm and equal to or less than 2 mm.

[0096] If the thickness of the solar cell encapsulation material is equal to or greater than the lower limit, it is possible to further improve the mechanical strength of the solar cell encapsulation material. If the thickness of the solar cell encapsulation material is equal to or less than the upper limit, it is also possible to further improve the transparency or interlayer adhesion of the resulting solar cell encapsulation material.

[0097] If the solar cell encapsulation material according to the present embodiment has a multi-layered structure, a layer formed from the resin composition (P) according to the present embodiment can be used as an outer layer or as an intermediate layer.

[0098] If the solar cell encapsulation material according to the present embodiment comprises outer layers and an intermediate layer, the thickness a of the outer layer is arbitrary, but is preferably in a range of 1 µm to 500 µm, more preferably in a range of 10 µm to 500 µm and particularly preferably in a range of 20 µm to 300 µm.

[0099] If the thickness a is equal to or greater than 1 µm, the adhesion strength can be further improved, and if the thickness a is equal to or less than 500 µm, the transparency is excellent.

[0100] Furthermore, if the solar cell encapsulation material according to the present embodiment comprises outer layers and an intermediate layer, the thickness of the intermediate layer can be considerable relative to the thickness of all layers with regard to transparency. In particular, the thickness b of the intermediate layer can be freely adjusted within a range of 0.1 mm to 10 mm, which is a preferred overall thickness, by subtracting the preferred thickness a of the outer layer.

[0101] Furthermore, if the solar cell encapsulation material according to the present embodiment comprises outer layers and an intermediate layer, the ratio of the thickness (a / b) between the outer layer (thickness a) and the intermediate layer (thickness b) is preferably 1 / 20 to 5 / 1, more preferably 1 / 15 to 3 / 1, and even more preferably 1 / 10 to 3 / 1. Here, in a case where the solar cell encapsulation material according to the present embodiment comprises two outer layers, the thickness a of the outer layer is the average of the thicknesses of the two outer layers.

[0102] If the thickness ratio (a / b) between the outer layer and the intermediate layer is within the range described above, adhesion and transparency will improve further.

[0103] A manufacturing process for a solar cell encapsulation material according to the present embodiment is not particularly restricted, and any conventionally known manufacturing process can be used.

[0104] For example, a compression molding process, an extrusion molding process, a T-nozzle molding process, an injection molding process, a compression molding process, a casting molding process, a calender molding process, a blow molding process, or the like can be used as a manufacturing process for a solar cell encapsulation material according to the present embodiment. Of these, the extrusion molding process is preferred. That is, the solar cell encapsulation material according to the present embodiment can be obtained, for example, by a manufacturing process that includes a step of extruding the resin composition (P) according to the present embodiment into a film form. The processing temperature in the extrusion step is not particularly limited, but is preferably below 220 °C and more preferably below 200 °C with regard to suppressing the crosslinking reaction. 3. Solar cell module

[0105] Fig. Figure 1 is a cross-sectional view that schematically shows an example of the structure of a solar cell module 1 of the embodiment according to the present invention.

[0106] A solar cell module 1 according to the present embodiment comprises, for example, a solar cell element 3 and an encapsulation resin layer 5, which is formed from the solar cell encapsulation material according to the present embodiment, for encapsulating the solar cell element 3. The solar cell module 1 according to the present embodiment may further comprise, as required, a substrate 2 onto which sunlight is incident, a protective material 4, or the like. In some cases, the substrate 2 onto which sunlight is incident is simply referred to as substrate 2.

[0107] The solar cell module 1 according to the present embodiment can be manufactured by fixing the solar cell element 3, which is encapsulated by the solar cell encapsulation material according to the present embodiment, onto the substrate 2.

[0108] Various types of solar cell modules can be represented as examples of such solar cell modules 1. Examples include a solar cell module with a structure in which a solar cell element is sandwiched between encapsulation materials on both sides of the solar cell element, as in the case of Substrate / encapsulation material / solar cell element / encapsulation material / protective material; a solar cell module in which a solar cell element pre-formed on the surface of a substrate, such as glass, is configured as in the case of substrate / solar cell element / encapsulation material / protective material; and a solar cell module having a structure in which an encapsulation material and a protective material are formed on a solar cell element formed on the inner circumferential surface of the substrate, for example, an amorphous solar cell element produced on a fluororesin-based film by sputtering or the like.

[0109] Furthermore, since the protective material 4, when the substrate 2, onto which sunlight falls, is defined as the upper part of the solar cell module 1, is provided on a side of the solar cell module 1 opposite the substrate 2, i.e. in the lower part, in this case it is also referred to as the lower protective material.

[0110] Various solar cell elements can be used as solar cell element 3, such as silicon-based solar cell elements containing monocrystalline silicon, polycrystalline silicon, amorphous silicon, or the like; and solar cell elements based on compound semiconductors of Group III-V or Group II-VI containing gallium arsenic, copper indium selenium, copper indium gallium selenium, cadmium tellurium, or the like. The solar cell encapsulation material according to the present embodiment is particularly useful for encapsulating a solar cell element made of amorphous silicon and a heterojunction-type solar cell element made of amorphous silicon and monocrystalline silicon.

[0111] The solar cell module 1 contains several of the Solar cell elements 3 are electrically connected in series by intermediate connectors 6.

[0112] Examples of the substrate 2 forming the solar cell module 1 according to the present embodiment include glass, an acrylic resin, a polycarbonate, a polyester, a fluorinated resin and the like.

[0113] The protective material 4 (lower protective material) is a single substance made of metals or various thermoplastic resin films, or a multilayer film, e.g., single- or multilayer films made of metals such as tin, aluminum, and stainless steel; inorganic materials such as glass; a polyester, an inorganic vapor-deposited polyester, a fluorinated resin, a polyolefin, and the like. The solar cell encapsulation material according to the present embodiment exhibits favorable adhesion to this substrate 2 or protective material 4.

[0114] The manufacturing process of the solar cell module 1 is not particularly restricted, and examples include the following process.

[0115] First, a plurality of solar cell elements 3, electrically connected using the intermediate connectors 6, are sandwiched between the solar cell encapsulation materials, and these solar cell encapsulation materials are further sandwiched between the substrate 2 and the protective material 4, thus producing a laminate. Then the laminate is heated and pressurized to bond the individual elements, thereby obtaining the solar cell module 1.

[0116] Up to this point, the embodiment of the present invention has been described with reference to the drawings, but this is an example of the present invention, and it is also possible to assume various other structures than those described above. [EXAMPLES]

[0117] The present invention is described in detail below based on examples, but the present invention is not limited to these examples. (1) Evaluation methods [Creep test]

[0118] A film made from each of the resin compositions obtained in the examples and comparative examples was cut into sheets measuring 180 mm × 160 mm × 0.4 mm. Two of these films were then laminated, sandwiched between 180 mm × 180 mm × 3.2 mm float glass sheets with a displacement of 2 cm, held under vacuum in a vacuum laminator at 150 °C for 3 minutes, and pressed at 0.1 MPa (overpressure) for 5 minutes, resulting in a laminated glass sheet. The displacement distance between the glass sheets was adjusted to achieve a shear stress of 9 kg / m² in the films. 2 was produced. Then, one pane of the resulting laminated glass was fixed in place while the other pane was freely movable, and the laminated glass was placed in a high-temperature, circulation-type dryer (manufactured by Sanyo Electric Co., Ltd., trade name: MOV-212F) set to 105 °C. The displacement length of the glass after 200 hours following placement in the dryer was measured, and the creep resistance of each of the resin compositions obtained in the examples and comparison examples was evaluated according to the following criteria. A (excellent): The creepage distance is equal to or less than 1 mm. B (favorable): The creepage distance is more than 1 mm and less than 5 mm. C (bad): The creepage distance is equal to or greater than 5 mm. [Optical properties]

[0119] A film of each of the resin compositions obtained in the examples and comparison examples was cut into sizes of 120 mm × 75 mm × 0.4 mm. The resulting film was then sandwiched between white glass plates measuring 120 mm × 75 mm × 3.2 mm, vacuum-laminated at 150 °C for 3 minutes, and pressed at 0.1 MPa (overpressure) for 5 minutes, resulting in a laminated glass. The opacity of the laminated glass was then measured according to JIS K 7136:2000 using an opacity meter (manufactured by Suga Test Instruments Co., Ltd., trade name: HAZE METER HZ-V3). The optical properties of each of the resin compositions obtained in the examples and comparison examples were then evaluated according to the following criteria. A (excellent): The turbidity is less than 3.0%. B (favorable): The turbidity is equal to or greater than 3.0% and less than 3.5%. C (bad): The turbidity is equal to or greater than 3.5%. [Observation of the appearance of educated films]

[0120] At the time of film formation from each of the resin compositions obtained in the examples and comparison examples, the appearance of the film, obtained in a state where the pressure induced by the squeeze roller was released, was visually observed. The appearance of the formed film of each of the resin compositions obtained in the examples and comparison examples was then evaluated according to the following criteria. A (excellent): Smooth and uniform appearance B (favorable): Unevenness is observed when forming along the MD direction. C (bad): Unevenness in shaping along the MD direction and significant gel formation are observed. [Interlayer adhesion]

[0121] A film of each of the resin compositions obtained in the examples and comparison examples was cut into sizes of 120 mm × 75 mm × 0.4 mm. The resulting film was then laminated onto one tin side of a 120 mm × 75 mm × 3.9 mm float glass sheet, held under vacuum at 160 °C for 690 seconds, and pressed at 0.06 MPa (overpressure) for 15 minutes, thereby bonding the film to the tin side of the glass sheet. The film was then peeled from the glass sheet at a peel rate of 100 mm / min at a peel angle of 180°, and the maximum stress was calculated as the bond strength (N / 15 mm) on the glass sheet. The interlayer adhesion in the laminated glass of each of the resin compositions obtained in the examples and comparison examples was then evaluated according to the following criteria.

[0122] A (excellent): The adhesion strength to the glass plate is equal to or greater than 30 N / 15 mm.

[0123] B (favorable): The adhesive strength on the glass plate is equal to or greater than 10 N / 15 mm and less than 30 N / 15 mm.

[0124] C (poor): The adhesion strength to the glass plate is less than 10 N / 15 mm. (2) Materials

[0125] The details of the raw materials used for the manufacture of solar cell encapsulation materials are as described below. <harze>

[0126] Resin A: Zn ionomer from ethylene methacrylic acid copolymer (Methacrylic acid content: 15% by mass) (Degree of neutralization: 23%, MFR (measured according to JIS K 7210: 1999 under conditions of 190 °C and a load of 2160 g): 5 g / 10 minutes) Resin B: Zn ionomer of ethylene methacrylic acid copolymer (methacrylic acid content: 15 wt%) (degree of neutralization: 21%, MFR (measured according to JIS K 7210: 1999 under conditions of 190 °C and a load of 2160 g): 16 g / 10 minutes) Resin-C: Zn ionomer of ethylene-methacrylic acid-i-butyl acrylate copolymer (methacrylic acid content: 10 wt%, i-butyl acrylate content: 10 wt%) (degree of neutralization: 70%, MFR (measured according to JIS K 7210: 1999 under conditions of 190 °C and a load of 2160 g): 1 g / 10 minutes) Resin-D: Na ionomer of ethylene methacrylic acid copolymer (methacrylic acid content: 15 wt%) (degree of neutralization: 54%, MFR (measured according to JIS K 7210: 1999 under conditions of 190 °C and a load of 2160 g): 0.9 g / 10 minutes) Resin-E: Ethylene-n-butyl acrylate-glycidyl methacrylate copolymer (n-butyl acrylate content: 21% by mass, glycidyl methacrylate content: 9% by mass, MFR (measured according to JIS K 7210: 1999 under conditions of 190 °C and a load of 2160 g): 8 g / 10 minutes) Resin-F: Ethylene-n-butyl acrylate-glycidyl methacrylate copolymer (n-butyl acrylate content: 28% by mass, glycidyl methacrylate content: 5.3% by mass, MFR (measured according to JIS K 7210: 1999 under conditions of 190 °C and a load of 2160 g): 12 g / 10 minutes) <silankupplungsmittel>

[0127] SCA: Silane coupling agent with an amino group (N-(2-Aminoethyl)-3-aminopropylmethyldimethoxysilane) [Examples 1 to 3 and comparison examples 1 to 4]

[0128] Individual materials were melted and kneaded at 160 °C in the formulation proportions shown in Table 1 to obtain individual resin compositions. The resulting resin compositions were then extruded under conditions of a resin temperature at the extruder nozzle of 160 °C and a processing speed of 1.2 to 1.3 m / min, yielding individual film-shaped solar cell encapsulation materials with a thickness of 0.4 mm. In Table 1, the units (phr) of the amounts of the silane coupling agent (SCA) and the formulated ethylene-based epoxy group copolymers (resin-E and resin-F) are given in parts by mass, where the total amount of ethylene-unsaturated carboxylic acid copolymer ionomers is defined as 100 parts by mass.

[0129] The evaluations described above were performed on each of the solar cell encapsulation materials obtained. The results are presented in Table 1. [Table 1] Basal resin Comonomer content [mass percent] Meta 11 Degree of neutralization [%] MFR [g / 10 min ] Example 1 Example 2 Example 3 Comparison example 1 Comparison example 2 Comparison example 3 Comparison example 4 Harz-A EMAA 15 Zn 23 5 100 percent by mass t 100 percent by mass t Harz-B EMAA 15 Zn 21 16 50 percent by mass 50 percent by mass 50 percent by mass 50 percent by mass t 50 percent by mass t Resin-C EMAAiB A MAA = 10 iBA = 10 Zn 70 1 20 percent by mass 20 percent by mass 20 percent by mass 20 percent by mass t 20 percent by mass t Harz-D EMAA 15 N / a 54 0,9 30 percent by mass 30 percent by mass 30 percent by mass 30 percent by mass t 30 percent by mass t Harz-E EnBAGM A nBA = 21 GMA = 9 8 1 phr 2 phr 2 phr Harz-F EnBAGM A nBA = 28 GMA = 5.3 12 2 phr SCA 0.25 phr 0.25 phr 0.25 phr 0.25 phr 0.25 phr Creep resistance B A B C B C C Optical properties (transparency) A B B B C A B Appearance of the film (gel) A B B A C A A Glass interlayer thaftuna A A A - A - B

[0130] The solar cell encapsulation materials of examples 1 to 3 were excellent with regard to the performance balance of transparency, creep resistance, interlayer adhesion, and appearance. Conversely, the solar cell encapsulation materials of comparison examples 1 to 4 were poor with regard to the performance balance of transparency, creep resistance, interlayer adhesion, and appearance.

[0131] This application claims priority based on Japanese patent application No. 2019-158111, filed on August 30, 2019, the entire disclosure of which is incorporated herein by reference. Reference symbol list 1 solar cell module 2 Substrat 3 solar cell elements 4 Protective material 5 Encapsulation resin layer 6 intermediate connectors QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2019158111

[0131] < / silankupplungsmittel> < / harze> < / kriechstrecke>

Claims

[1] Resin composition used to form a solar cell encapsulation material, the resin composition comprising: an ionomer (A) of a copolymer based on ethylene and unsaturated carboxylic acids; and an ethylene-based copolymer containing epoxy groups (B), wherein the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid contains two or more types of metal ions. [2] Resin composition for a solar cell encapsulation material according to claim 1, wherein the metal ions forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid comprise two or more ions selected from the group consisting of a lithium ion, a potassium ion, a sodium ion, a silver ion, a copper ion, a calcium ion, a magnesium ion, a zinc ion, an aluminum ion, a barium ion, a beryllium ion, a strontium ion, a tin ion, a lead ion, an iron ion, a cobalt ion and a nickel ion. [3] Resin composition for a solar cell encapsulation material according to claim 1 or 2, wherein the metal ions forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid comprise a first metal ion and a second metal ion which is different from the first metal ion, the first metal ion comprises at least one metal ion selected from the group consisting of a sodium ion, a lithium ion, a potassium ion and a magnesium ion, and the second metal ion comprises at least one metal ion selected from the group consisting of a zinc ion, a copper ion, an iron ion, an aluminum ion, a silver ion, a cobalt ion and a nickel ion. [4] Resin composition for a solar cell encapsulation material according to claim 3, wherein in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid, the ratio of a value obtained by multiplying a mole number of the second metal ion by a valence to a value obtained by multiplying a mole number of the first metal ion by a valence is equal to or greater than 0.10 and equal to or less than 10.

0. [5] Resin composition for a solar cell encapsulation material according to any one of claims 1 to 4, wherein, where a total amount of the resin composition for a solar cell encapsulation material is defined as 100% by mass, the content of the epoxy group containing ethylene-based copolymer (B) is less than 10.0% by mass. [6] Resin composition for a solar cell encapsulation material according to any one of claims 1 to 5, wherein the resin composition further comprises: a silane coupling agent (C). [7] Resin composition for a solar cell encapsulation material according to claim 6, wherein the silane coupling agent (C) comprises a silane coupling agent with an amino group. [8] Resin composition for a solar cell encapsulation material according to one of claims 1 to 7, wherein the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid comprises an ionomer (A1) of a binary copolymer of ethylene and an unsaturated carboxylic acid and an ionomer (A2) of a ternary copolymer of ethylene, an unsaturated carboxylic acid and an unsaturated carboxylic acid ester. [9] Resin composition for a solar cell encapsulation material according to any one of claims 1 to 8, wherein an unsaturated carboxylic acid forming the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid comprises at least one acid selected from an acrylic acid and a methacrylic acid. [10] Resin composition for a solar cell encapsulation material according to any one of claims 1 to 9, wherein the ethylene-based epoxy group containing copolymer (B) comprises at least one selected from an ethylene glycidyl(meth)acrylate copolymer, an ethylene glycidyl(meth)acrylate vinyl acetate copolymer and an ethylene glycidyl(meth)acrylate(meth)acrylate ester copolymer. [11] Resin composition for a solar cell encapsulation material according to any one of claims 1 to 10, wherein in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid, where a total amount of the constituent units forming the copolymer based on ethylene and unsaturated carboxylic acid is defined as 100% by mass, a constituent unit derived from the unsaturated carboxylic acid is equal to or greater than 5% by mass and equal to or less than 35% by mass. [12] Resin composition for a solar cell encapsulation material according to any one of claims 1 to 11, wherein the degree of neutralization of the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid is equal to or greater than 5% and equal to or less than 95%. [13] Resin composition for a solar cell encapsulation material according to one of claims 1 to 12, wherein at least part of a carboxyl group in the ionomer (A) of the copolymer based on ethylene and unsaturated carboxylic acid and at least part of an epoxide group in the epoxide group-containing copolymer based on ethylene (B) react with each other to form a crosslinking structure. [14] Resin composition for a solar cell encapsulation material according to any one of claims 1 to 13, where the turbidity measured according to the following procedure is less than 3.5%, (Procedure) A 120 mm × 75 mm × 0.4 mm film, formed from the resin composition for a solar cell encapsulation material, is obtained. The obtained film is then sandwiched between glass plates of 120 mm × 75 mm × 3.2 mm, held under vacuum in a vacuum laminator at 150 °C for 3 minutes, and pressed at 0.1 MPa (overpressure) for 5 minutes, resulting in a laminated glass. The opacity of the obtained laminated glass is then measured with a opacity meter according to JIS K 7136: 2000. [15] Resin composition for a solar cell encapsulation material according to any one of claims 1 to 14, where the adhesive strength on a glass plate, measured by the following method, is equal to or greater than 10 N / 15 mm. (Procedure) A 120 mm × 75 mm × 0.4 mm film, formed from the resin composition for a solar cell encapsulation material, is obtained. The resulting film is then laminated onto a tin side of a 120 mm × 75 mm × 3.9 mm glass plate, held under vacuum in a vacuum laminator at 160 °C for 690 seconds and pressed for 15 minutes at 0.06 MPa (overpressure), thereby bonding the film to the tin side of the glass plate. The film is then peeled from the glass plate at a pulling speed of 100 mm / min at a peel angle of 180°, and the maximum stress is calculated as the bond strength (N / 15 mm) on the glass plate. [16] Resin composition for a solar cell encapsulation material according to any one of claims 1 to 15, where a creepage distance measured according to the following procedure is less than 5 mm, (Procedure) Films measuring 180 mm × 160 mm × 0.4 mm are obtained, formed from the resin composition for a solar cell encapsulation material. Two of these films are then laminated and sandwiched between 180 mm × 180 mm × 3.2 mm float glass panes with a displacement of 2 cm. The laminated glass is held under vacuum at 150 °C for 3 minutes and pressed at 0.1 MPa (overpressure) for 5 minutes, resulting in a laminated glass. Finally, with one pane of the laminated glass fixed and the other pane freely movable, the displacement length of the glass is measured after 200 hours at 105 °C. [17] Encapsulation material for solar cells, comprising: a layer formed from the resin composition for a solar cell encapsulation material according to any one of claims 1 to 16. [18] Manufacturing process of a solar cell encapsulation material, the process comprising: a step of extruding the resin composition for a solar cell encapsulation material according to one of claims 1 to 16 into a film form. [19] Solar cell module, comprising: a solar cell element; and an encapsulation resin layer formed from the solar cell encapsulation material according to claim 17, for encapsulating the solar cell element.