WO2017010383A1 - Solar battery module, conductive material for solar battery module, and wiring structure - Google Patents

Abstract

The present invention addresses the problem of providing a solar battery module with which power generation efficiency can be improved. The present invention provides a solar battery module comprising multiple solar battery cells arrayed with intervals therebetween, and a conductive part that electrically connects two adjacent solar battery cells from among the multiple solar battery cells. In this solar battery module, at least the surface of the solar battery module on the light incident surface side of the conductive part has diffuse reflectivity of 60% or greater.

Description

Solar cell module, conductive material for solar cell module and wiring structure

The present invention relates to a solar cell module, a conductive material for a solar cell module, and a wiring structure.
This application claims priority based on Japanese Patent Application No. 2015-139211 filed on July 10, 2015 and Japanese Patent Application No. 2015-218977 filed on November 6, 2015. The entire contents of these applications are hereby incorporated by reference.

Solar cell modules that convert light energy into electric power are widely used as clean power generators. The solar cell module includes a solar cell and a wiring connected to the cell, and the power generated in the cell through the wiring is configured to be supplied to the outside. Patent documents 1 to 7 are cited as documents disclosing this type of prior art.

Japanese published patent publication 2005-536894 Japanese Patent No. 5185913 Japanese Patent Application Publication No. 2014-63978 Japanese Patent Application Publication No. 2011-142127 Japanese Patent No. 4646558 Japanese Patent No. 5269014 Japanese Published Patent Publication No. 2009-518823

An attempt to improve the power generation efficiency of solar cell modules has been made from various directions. For example, with respect to the wiring on the surface of the solar battery cell, an attempt has been made to reduce the optical loss due to the wiring portion by forming irregularities having a specific angle on the surface of the wiring that receives sunlight (see Patent Documents 5 to 7). ). However, these methods are not efficient because it is necessary to perform uneven processing on the wiring surface. Also, in these documents, the influence of roughness and wiring material on each surface of the unevenness is not examined. The present inventors have confirmed that the reflection angle of incident light on the wiring surface is affected by the roughness and material of the surface. Even if an uneven surface having a predetermined angle is provided on the wiring surface, the optical loss cannot always be effectively reduced due to other factors such as surface roughness.

The present invention was created in view of the above circumstances, and an object thereof is to provide a solar cell module that can improve power generation efficiency. Another related object is to provide a conductive material and a wiring structure that can improve power generation efficiency.

According to the present invention, a solar cell module comprising a plurality of solar cells arranged at intervals and a conductive portion that electrically connects two adjacent solar cells among the plurality of solar cells. Provided. In this solar cell module, at least the solar cell module incident surface side surface of the conductive portion exhibits a diffuse reflectance of 60% or more.
According to said structure, the light reception amount in the photovoltaic cell surface increases by making the diffuse reflectance of the electroconductive part surface more than predetermined value, and electric power generation efficiency improves.

In a preferred embodiment of the technology disclosed herein (including a solar cell module, a conductive material, a wiring structure, and a manufacturing method thereof, the same applies hereinafter), at least a solar cell module light incident surface side surface of the conductive portion. Indicates a diffuse reflectance of 80% or more. By comprising in this way, the more outstanding power generation efficiency improvement effect is acquired.

In a preferred embodiment of the technology disclosed herein, the arithmetic average roughness (Ra) of at least the solar cell module light incident surface side of the conductive portion is 60 nm or more. By having the Ra, the diffuse reflectance is improved, and consequently the power generation efficiency is improved.

In a preferred aspect of the technology disclosed herein, at least the solar cell module light incident surface side surface of the conductive portion is made of silver having a purity of 99.7% by weight or more. By increasing the purity of silver on the surface, the diffuse reflectance is increased and the power generation efficiency is improved. In particular, when the surface made of the high-purity silver is Ra of Ra 60 nm or more (for example, 70 nm or more, preferably 80 nm or more), the diffuse reflectance can be significantly improved.

In a preferred aspect of the technology disclosed herein, the conductive portion is composed of a plurality of metal wires arranged at intervals. By comprising in this way, high current collection efficiency is realizable, suppressing the increase in shadow loss. In a more preferred embodiment, the metal wire is plated with a thickness of 1.5 μm or more. By configuring in this way, it is easy to obtain a diffuse reflectance higher than a predetermined value.

Further, according to the present invention, there is provided a conductive material that electrically connects two adjacent solar cells among a plurality of solar cells arranged in the solar cell module. The conductive material has a surface that exhibits a diffuse reflectance of 60% or more. Power generation efficiency of the solar cell module is improved by using the conductive material for the wiring of the solar cell and disposing the surface showing a predetermined diffuse reflectance on the light incident surface side of the solar cell module.

Further, according to the present invention, there is provided a wiring structure that electrically connects two adjacent solar cells among a plurality of solar cells arranged in the solar cell module. The wiring structure includes a transparent resin layer and a conductive portion partially disposed on the first surface of the transparent resin layer. Further, at least the transparent resin layer side surface of the conductive portion exhibits a diffuse reflectance of 60% or more. By using the wiring structure for wiring of solar cells, the power generation efficiency of the solar cell module is improved. The arithmetic mean roughness (Ra) of at least the transparent resin layer side surface of the conductive part is preferably 60 nm or more. Moreover, it is preferable that at least the transparent resin layer side surface of the conductive part is made of silver having a purity of 99.7% by weight or more. Moreover, it is preferable that the said transparent resin layer is an adhesive layer. More preferably, the transparent resin layer is a crosslinked pressure-sensitive adhesive layer.

It is sectional drawing which shows typically the principal part of the solar cell module which concerns on one Embodiment. It is a top view which expands and shows a part of principal part of the solar cell module concerning one embodiment typically. FIG. 3 is a schematic cross-sectional view taken along line III-III in FIG. 2. It is sectional drawing which expands and shows the electroconductive part in FIG. 3 typically. It is a top view which shows typically the wiring structure which concerns on one Embodiment. FIG. 6 is a cross-sectional view taken along line VI-VI of the wiring structure of FIG. 5. FIG. 7 corresponds to FIG. 6, and is a cross-sectional view schematically showing a wiring structure with a release liner according to an embodiment. It is explanatory drawing of the wiring method of the solar cell module which concerns on one Embodiment. It is a graph which shows the measurement result of the diffuse reflectance (%) of the electrically conductive part surface in Experiment 1, and short circuit current Jsc (mA / cm < ² >). It is a graph which shows the relationship between the plating thickness (micrometer) in Experiment 2, and a diffuse reflectance (%).

Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than the matters specifically mentioned in the present specification and necessary for the implementation of the present invention are based on the teachings on the implementation of the invention described in the present specification and the common general technical knowledge at the time of filing. Can be understood by those skilled in the art. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field. Further, in the following drawings, members / parts having the same action are described with the same reference numerals, and overlapping descriptions may be omitted or simplified. In addition, the embodiments described in the drawings are schematically illustrated in order to clearly explain the present invention, and do not necessarily accurately represent the size and scale of a product actually provided.

≪Solar cell module≫
FIG. 1 is a cross-sectional view schematically illustrating a main part of a solar cell module according to an embodiment. FIG. 2 is a top view schematically showing an enlarged part of the main part of the solar cell module according to one embodiment. 3 is a schematic cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view schematically showing the conductive portion in FIG. 3 in an enlarged manner.

As shown in FIG. 1, the solar cell module 100 covers (encloses) the solar cell group 110 including a plurality of solar cells including the solar cells 110a, 110b, 110c, and 110d, and the solar cell group 110. A sealing resin 150, and a front surface covering member 160 and a back surface covering member 170 disposed so as to sandwich the sealing resin 150 are provided. In this embodiment, crystalline Si cells (approximately 15.5 cm × 15.5 cm) are used as the solar cells 110a, 110b, 110c, and 110d, and an ethylene-vinyl acetate copolymer (EVA) is used as the sealing resin 150. A glass plate having a thickness of 3.2 mm is used as the surface covering member 160, and a commercially available back sheet is used as the back surface covering member 170.

A plurality of solar cells including the solar cells 110 a, 110 b, 110 c, and 110 d are arranged in a line in a straight line at a predetermined interval to constitute a solar cell group 110. An n-type electrode (front electrode) is partially formed on the upper surface (front surface) of solar cells 110a, 110b, 110c, and 110d, and a p-type electrode (rear surface) is formed on the lower surface (back surface). Electrode). In addition, the upper and lower sides of the solar battery cell in this specification correspond to the front and back of the solar battery cell, and thus correspond to the front and back (upper and lower) of the solar battery module. The surface of the solar cell module is a light incident surface. Depending on how the solar cell module is installed, the top and bottom may not necessarily be strictly up and down, so the top and bottom of the solar cells are not limited to exact top and bottom, and are understood to indicate relative positional relationships. The

In the solar cell group 110, two adjacent solar cells (for example, the solar cell 110a and the solar cell 110b) are electrically connected by one conductive portion 30a. The conductive portion 30a extends from the upper surface of the solar battery cell 110a to the lower surface of the solar battery cell 110b. More specifically, the one conductive portion 30a is disposed on the upper surface of the solar battery cell 110a above the solar battery cell group 110, and passes through the space between the solar battery cell 110a and the solar battery cell 110b. It moves below the solar cell group 110 and is disposed on the lower surface of the solar cell 110b. The conductive portion 30a extends from the end of the solar cell 110a (the end opposite to the solar cell 110b side) to the end of the solar cell 110b (the end opposite to the solar cell 110a side), It contacts (specifically, contacts) the upper surface of the solar battery cell 110a and the lower surface of the solar battery cell 110b. As described above, since the conductive portion 30a is a single member and is continuous from the upper surface of the solar battery cell 110a to the lower surface of the solar battery cell 110b, the connection reliability is high and the durability is excellent.

As shown in FIG. 2, the conductive portion 30a of this embodiment is composed of a plurality of metal wires 40a extending from the upper surface of the solar battery cell 110a to the lower surface of the solar battery cell 110b. The plurality of metal wires 40a extend along the arrangement direction of the solar cells 110a and 110b, and are arranged at intervals. These metal wires 40a are arranged in a straight line so as to be parallel to each other. In the arrangement direction of the solar cells 110a and 110b, substantially both ends of the solar cells 110a and 110b (ends of the solar cells 110a (solar cells) 110b (the end opposite to the 110b side)) to the end of the solar battery cell 110b (the end opposite to the solar battery 110a side).

In the solar cell module 100, the first resin layer 50a is disposed above the solar cell group 110. Specifically, one first resin layer 50a is disposed only above one solar battery cell 110a, and is not disposed above another solar battery cell (for example, solar battery cell 110b). A different first resin layer (for example, the first resin layer 50b) is disposed above another solar cell (for example, the solar cell 110b). Moreover, the 1st resin layer 50a is arrange | positioned above the electroconductive part 30a located above the photovoltaic cell 110a. In other words, the conductive part 30a is disposed between the solar battery cell 110a and the first resin layer 50a. The first resin layer 50a has substantially the same shape and size as the solar battery cell 110a, and does not protrude from the upper surface of the solar battery cell 110a. The first resin layer 50a of this embodiment has a substantially square shape (specifically, a substantially square shape having a size of approximately 15.5 cm × 15.5 cm).

The first resin layer 50a is a transparent resin layer, and at least the surface on the solar cell side has adhesiveness. The first resin layer 50a of this embodiment is a transparent pressure-sensitive adhesive layer. As shown in FIG. 3, the first resin layer 50a is in contact with the upper surface of the solar battery cell 110a from above the conductive portion 30a in the non-existing region of the conductive portion 30a. Specifically, the 1st resin layer 50a is adhere | attached on the upper surface of the photovoltaic cell 110a through the electroconductive part 30a from the space between the some metal wires 40a as the electroconductive part 30a. That is, the lower surface (surface on the solar cell side) of the first resin layer 50a is bonded to the conductive portion 30a (specifically, the plurality of metal wires 40a) and is not bonded to the conductive portion 30a. It adheres to the upper surface of the solar battery cell 110a. Thus, the conductive portion 30a is reliably and stably brought into contact (specifically, contacted) with the upper surface of the solar battery cell 110a.

The second resin layer 60 a is disposed below the solar battery cell group 110 in the solar battery module 100. Specifically, one second resin layer 60a is disposed only below one solar battery cell 110a, and is not disposed below another solar battery cell (for example, solar battery cell 110b). A different second resin layer (for example, second resin layer 60b) is disposed below another solar cell (for example, solar cell 110b). Moreover, the 2nd resin layer 60a is arrange | positioned below the electroconductive part 30z located under the photovoltaic cell 110a. In other words, the conductive part 30z is disposed between the solar battery cell 110a and the second resin layer 60a. The second resin layer 60a has substantially the same shape and size as the solar battery cell 110a, and does not protrude from the lower surface of the solar battery cell 110a. The second resin layer 60a of this embodiment has a substantially square shape (specifically, a substantially square shape having a size of approximately 15.5 cm × 15.5 cm).

The second resin layer 60a has at least a solar cell side surface having adhesiveness. The second resin layer 60a is a transparent adhesive layer in this embodiment. The second resin layer 60a is in contact with the lower surface of the solar battery cell 110a in the non-existing region of the conductive part 30z from below the conductive part 30z. Specifically, the 2nd resin layer 60a is adhere | attached on the lower surface of the photovoltaic cell 110a through the electroconductive part 30z from the space between the some metal wires 40z as the electroconductive part 30z. That is, the upper surface (surface on the solar cell side) of the second resin layer 60a is bonded to the conductive portion 30z (specifically, the plurality of metal wires 40z) and is not bonded to the conductive portion 30z. It is bonded to the lower surface of the solar battery cell 110a. Thus, the conductive portion 30z is reliably and stably brought into contact with the lower surface of the solar battery cell 110a.

The second resin layer 60b is basically configured in the same manner as the second resin layer 60a except that the second resin layer 60b is disposed below the solar battery cell 110b. Specifically, the second resin layer 60 b is disposed below the solar battery cell group 110. The 2nd resin layer 60b is arrange | positioned only under the photovoltaic cell 110b, and is not arrange | positioned under the other photovoltaic cell (for example, photovoltaic cell 110a, 110c). Different second resin layers (for example, second resin layers 60a and 60c) are disposed below other solar cells (for example, solar cells 110a and 110c). Moreover, the 2nd resin layer 60b is arrange | positioned below the electroconductive part 30a located under the photovoltaic cell 110b. In other words, the conductive part 30a is disposed between the solar battery cell 110b and the second resin layer 60b. The second resin layer 60b has substantially the same shape and size as the solar battery cell 110b, and does not protrude from the lower surface of the solar battery cell 110b. The second resin layer 60b in this embodiment has a substantially square shape (specifically, a substantially square shape having a size of approximately 15.5 cm × 15.5 cm).

The second resin layer 60b has an adhesive property at least on the solar cell side surface. The second resin layer 60b is a transparent adhesive layer in this embodiment. The second resin layer 60b is in contact with the lower surface of the solar battery cell 110b from below the conductive portion 30a in the non-existing region of the conductive portion 30a. Specifically, the 2nd resin layer 60b is adhere | attached on the lower surface of the photovoltaic cell 110b through the electroconductive part 30a from the space between the some metal wires 40a as the electroconductive part 30a. That is, the upper surface (surface on the solar cell side) of the second resin layer 60b is bonded to the conductive portion 30a (specifically, the plurality of metal wires 40a) and is not bonded to the conductive portion 30a. It is bonded to the lower surface of the solar battery cell 110b. Thus, the conductive portion 30a is reliably and stably brought into contact with the lower surface of the solar battery cell 110b.

As shown in FIG. 4, the metal wire 40 a has a core material 42 and a covering portion 44 that covers the surface of the core material 42. In this embodiment, a copper wire is used as the core member 42, and silver plating is applied as the covering portion 44. Moreover, the metal wire 40a has a rectangular shape in a cross section orthogonal to the longitudinal direction. One long side (downward) of the rectangular shape is in contact with the surface (upper surface) of the solar battery cell 110a. Thereby, the whole area of the lower surface of the metal wire 40a can be in surface contact with the surface of the solar battery cell 110a. The other long side (upper side) of the rectangular cross section of the metal wire 40a is a solar cell module light incident surface side surface 40A. In this embodiment, a metal wire having a width of 0.8 mm and a thickness of 0.25 mm is used as the metal wire 40a. The metal wire 40a is rounded at each corner of its cross section.

The surface of the metal wire 40a (the surface of the conductive part 30a) exhibits a diffuse reflectance of 60% or more. Thereby, the light incident from the solar cell module incident surface can diffusely reflect on the surface of the metal wire 40a and reach the surface of the solar cell, thereby improving the power generation efficiency. Here, the diffuse reflectance refers to the diffuse reflectance with respect to light having a wavelength of 550 nm (the ratio (%) of diffuse reflection with respect to incident light). The diffuse reflectance is more preferably 80% or more, further preferably 85% or more, particularly preferably 87% or more, and particularly preferably 90% or more.

In this embodiment, the entire outer surface (outer periphery) of the conductive portion 30a (more specifically, the metal wire 40a) exhibits the diffuse reflectance, but is not limited thereto. Specifically, at least the solar cell module light incident surface side surface 30A (40A) of the conductive portion 30a (more specifically, the metal wire 40a) may exhibit the diffuse reflectance, and further, the conductive portion. The outer surface of the surface 30a (more specifically, the metal wire 40a) other than the surface facing the solar battery 110a may exhibit the diffuse reflectance. Even if it is such a structure, the light reflected on the solar cell module light-incidence surface side surface 30A is effectively used on the solar cell surface, and the power generation efficiency can be improved. Therefore, in the metal wire 40a (and hence the conductive portion 30a), it is important that the surface showing the diffuse reflectance of 60% or more is the solar cell module light incident surface side surface 40A (and thus 30A). The diffuse reflectance is more preferably 80% or more, further preferably 85% or more, particularly preferably 87% or more, and particularly preferably 90% or more.

Further, the ratio of diffuse reflection (diffuse reflection ratio) to the total reflection on the surface of the conductive portion 30a (more specifically, the metal wire 40a) is preferably about 80% or more. Specifically, the diffuse reflection ratio refers to the ratio (%) of diffuse reflection in total reflection (the sum of regular reflection (also referred to as specular reflection) and diffuse reflection) with respect to light having a wavelength of 550 nm. The diffuse reflection ratio is more preferably 90% or more, further preferably 95% or more, and particularly preferably 99% or more. Moreover, in the technique disclosed here, even if at least the solar cell module light incident surface side surface 30A (40A) of the conductive portion 30a (more specifically, the metal wire 40a) exhibits the diffuse reflection ratio. Moreover, the outer surface of the conductive portion 30a (more specifically, the metal wire 40a) other than the surface facing the solar battery 110a may exhibit the diffuse reflection ratio. Therefore, the diffuse reflection ratio on the solar cell module light incident surface side surface 40A of the metal wire 40a (the solar cell module light incident surface side surface 30A of the conductive portion 30a) is preferably 80% or more. The diffuse reflection ratio is more preferably 90% or more, further preferably 95% or more, and particularly preferably 99% or more.

In this specification, the diffuse reflectance and diffuse reflectance ratio can be measured using a commercially available spectrophotometer. For example, an integrating sphere unit manufactured by JASCO (for example, product name “ISV-722”), a spectrophotometer manufactured by the same (for example, product name “V-660”), and a standard white plate manufactured by Labsphere (for example, Spectralon ( (Registered trademark) 6916-H422A). The measurement is performed on the portion of the conductive portion that is the surface on the light incident surface side of the solar cell module. Moreover, when the irradiation area of the electroconductive part (for example, metal wire) which is a measuring object is inadequate, it shall measure by arranging a several electroconductive part closely. In the examples described later, the same method is used.

Further, the arithmetic average roughness (Ra) of the surface (at least the solar cell module light incident surface side surface 30A) of the conductive portion 30a (more specifically, the metal wire 40a) is preferably about 60 nm or more. This tends to increase the diffuse reflectance and improve the power generation efficiency. The Ra is more preferably 70 nm or more, further preferably 80 nm or more (for example, 110 nm or more, further for example, 140 nm or more), and particularly preferably 200 nm or more (for example, 220 nm or more, further, for example, 250 nm or more). In particular, the surface (at least the solar cell module light incident surface side surface 30A) of the conductive portion 30a (more specifically, the metal wire 40a) is made of silver (typically a silver plating layer), and its purity is 99. Applying Ra in the above range to a structure having a thickness of 0.7% by weight or more (preferably 99.9% by weight or more) and a silver film thickness of 1.0 μm or more (preferably 1.5 μm or more). Thus, the diffuse reflectance can be significantly improved. On the other hand, by limiting Ra on the surface of the conductive portion 30a to a predetermined value or less, a good contact state with the solar battery cell 110a is easily obtained. The Ra can be adjusted by selecting a metal material type on the surface of the conductive portion, roughening using an embossing roll, surface treatment such as etching (for example, core material etching), and the like.

In this specification, the arithmetic average roughness (Ra) of the conductive part surface is measured by the following method. First, a shape profile is measured for the surface of the conductive portion using an optical interference type shape measuring device. The measurement range is about 600 μm × 450 μm. As the optical interference type shape measuring device, an optical interference type shape measuring device manufactured by Veeco, model “Wyko NT9100” or its equivalent may be used. After removing the waviness included in the obtained measurement result by Gaussian processing, Ra of the surface of the conductive portion is calculated. When the conductive part is composed of a plurality of (for example, three or more) metal wires, Ra is calculated by the above method for any three of the conductive parts, and the value obtained by arithmetically averaging them is defined as Ra on the surface of the conductive part. It is preferable to adopt. In the examples described later, the same method is used.

The above configuration will be described in terms of a cross-sectional structure as follows. That is, in the arrangement | positioning location of the photovoltaic cell 110a, the solar cell module 100 is the surface coating member 160 / sealing resin 150 / first resin layer 50a / conductive part 30a / solar battery cell 110a / conductive part 30z / from the top. The second resin layer 60a / sealing resin 150 / back surface covering member 170 has a cross-sectional structure in which the layers are laminated in this order. Moreover, in the arrangement | positioning location of the photovoltaic cell 110b, the solar cell module 100 is the surface coating member 160 / sealing resin 150 / first resin layer 50b / conductive part 30b / solar battery cell 110b / conductive part 30a / from the top. The second resin layer 60b / sealing resin 150 / back surface covering member 170 has a cross-sectional structure in which the layers are laminated in this order. The conductive part 30a disposed on the front surface side of the solar battery cell 110a and the conductive part 30z disposed on the back surface side of the solar battery cell 110a are separate members. Moreover, the electroconductive part 30b arrange | positioned at the surface side of the photovoltaic cell 110b and the electroconductive part 30a arrange | positioned at the back surface side of the photovoltaic cell 110b are also separate members. However, the conductive portion 30a disposed on the front surface side of the solar battery cell 110a and the conductive portion 30a disposed on the back surface side of the solar battery cell 110b are continuous members. Further, between the solar cells 110a and 110b, the solar cell module 100 is laminated in this order from the top to the surface covering member 160 / sealing resin 150 / conductive portion 30a / sealing resin 150 / back surface covering member 170. Having a cross-sectional structure.

The solar cells 110a and 110b and the configuration relating to their electrical connection have been described above. However, in the solar cell module 100, the other solar cells 110c and 110d and the conductive portion 30b that constitute the solar cell group 110 are included. 30c, 30d, the metal wire 40b, the first resin layers 50b, 50c, 50d, and the second resin layers 60b, 60c, 60d are basically the same in structure, and therefore redundant description is omitted. . The conductive portions (more specifically, metal wires) arranged on the upper or lower surface of the solar cells located at both ends of the solar cell group 110 are not electrically connected between the solar cells, but are not shown. Connected to electrode (terminal bar). Moreover, the solar cell module 100 having the above-described configuration may be manufactured using a wiring structure described below, and a conductive material described later, a constituent material such as a first resin layer, a second resin layer, or the like is appropriately used in the module. You may produce by arrange | positioning in an arbitrary place.

≪Conductive material for solar cell module≫
Next, conductive materials used as the conductive portions 30a, 30b, 30c, 30d, and 30z in the solar cell module 100 will be described. Such a conductive material (which may also be a conductive portion in a solar cell module; hereinafter the same) has a diffuse reflectance of 60% or more on its surface (at least the surface on the solar cell module light incident surface side). The diffuse reflectance is more preferably 80% or more, further preferably 85% or more, particularly preferably 87% or more, and particularly preferably 90% or more. Moreover, it is preferable that the diffuse reflection ratio in the surface (at least solar cell module light-incidence surface side surface) of a electrically conductive material is 80% or more. The diffuse reflection ratio is more preferably 90% or more, further preferably 95% or more, and particularly preferably 99% or more.

In addition, the arithmetic average roughness (Ra) of the surface of the conductive material (at least the surface on the solar cell module light incident surface side) is preferably 60 nm or more. The Ra is more preferably 70 nm or more, further preferably 80 nm or more (for example, 110 nm or more, further for example, 140 nm or more), and particularly preferably 200 nm or more (for example, 220 nm or more, further, for example, 250 nm or more). In particular, the surface of the conductive material (at least the surface on the light incident surface side of the solar cell module) is made of silver (typically a silver plating layer), and its purity is 99.7% by weight or more (preferably 99.9% by weight). %), And applying the Ra in the above range to a structure having a silver film thickness of 1.0 μm or more (preferably 1.5 μm or more) can significantly improve the diffuse reflectance. it can.

The conductive material for a solar cell module disclosed herein includes a conductive material. A typical example of the conductive material is a metal material. As a material constituting the conductive material, one or more metal materials such as gold, silver, copper, aluminum, iron, nickel, tin, chromium, bismuth, indium, zinc, and alloys thereof can be preferably used. Among these, silver, copper, aluminum, and iron are more preferable, and silver, copper, and aluminum are more preferable. Conductive paths composed essentially of metal have the advantage of lower resistance. As a typical example, a conductive material composed of a metal wire can be given. As the metal wire, those having a tensile strength measured according to JIS Z 2241: 2011 of 200 N / mm ² or more are preferably used from the viewpoint of strength, handling property, and the like. As a specific example, a copper metal wire is preferably used. Especially, the metal wire by which plating, such as tin (Sn) and silver (Ag), was given as a coating | coated part using a copper metal wire as a core material is more preferable. The film thickness (for example, plating thickness) of the covering portion may be about 10 μm or less (for example, 5 μm or less, and further, for example, 3 μm or less). The film thickness is suitably about 0.1 μm or more (for example, 0.5 μm or more). From the viewpoint of improving the diffuse reflectance, it is preferably 1.0 μm or more, more preferably 1.5 μm or more (for example, 2 μm). Further, for example, 3 μm or more). As a method for forming the covering portion, a conventionally known method such as a clad method can be adopted in addition to the above-described plating method.

The portion of the conductive material located on the lower surface (back surface) of the solar battery cell 110b may be a conductive sheet. The conductive sheet is typically a metal sheet (for example, a metal foil). As said metal sheet, what gave at least 1 sort (s) of surface treatment of a roughening process, a rust prevention process, and an adhesive improvement process is used preferably. Suitable examples of the metal sheet include copper foil (in particular, electrolytic copper foil). In the conductive material, when the portion disposed on the upper surface (front surface) of the solar battery cell 110a is a metal wire and the portion located on the lower surface (back surface) of the solar battery cell 110b is a conductive sheet, the conductive material is a metal wire. It is produced by fixing the conductive sheet. As a method for fixing the metal wire and the conductive sheet, it is preferable to employ welding. As the welding method, conventionally known various types of welding can be employed. For example, arc welding, resistance welding, laser beam welding, electron beam welding, and ultrasonic welding are preferably employed. Or it is also possible to employ | adopt the fixing method by plating joining and a conductive adhesive.

When the conductive material has a combined shape of, for example, a metal wire and a conductive sheet, the conductive material may be formed from a patterned metal sheet. Such a conductive material can be formed by etching a metal sheet. Specifically, a resist is attached to the surface of a metal sheet (typically a metal foil), and a predetermined resist pattern is formed by applying a photolithography technique. Next, the metal sheet is patterned using a known or conventional etching solution. In this way, the conductive material is formed. A similar configuration can be obtained by various vapor deposition methods.

Alternatively, the conductive material may be formed, for example, by applying a conductive paste as a conductive material. As the conductive paste, conductive components made of metal materials such as gold, silver, copper, aluminum, iron, nickel, tin, chromium, bismuth, indium, and alloys thereof, and conductive components made of non-metals such as carbon (hereinafter referred to as “conductive paste”) The same)) and a resin component such as polyester or epoxy resin can be used in a suitable solvent. Especially, it is preferable to use silver or copper as a conductive component from a viewpoint of temporal stability. Specific examples of the conductive paste include silver paste (trade name “Pertron K-3105”, manufactured by Pernox, conductive component: Ag, resin component: polyester resin, specific resistance: 6.5 × 10 ⁻⁵ Ω · cm) Is mentioned. The specific resistance of the conductive paste at 25 ° C. is about 5 × 10 ⁻⁴ Ω · cm or less (for example, 1 × 10 ⁻⁴ Ω · cm or less, typically 5.0 × 10 ⁻⁷ Ω · m or less). Preferably there is. The specific resistance of the conductive component constituting the conductive paste is preferably 5.0 × 10 ⁻⁷ Ω · m or less. The conductive material can be formed by applying a conductive paste to the surface of a resin layer, a peelable support or the like using a known dispenser.

In a preferred embodiment, the surface of the conductive material (at least the solar cell module light-incident surface side surface. Typically, the surface layer portion thereof. For example, the portion having a depth of 1 μm or less from the surface of the conductive material. The same applies hereinafter). Become. As such a conductive material, a metal material (for example, copper wire) subjected to silver plating can be used. When the surface of the conductive material is composed of silver, the purity of silver on the surface (for example, the purity of silver plating) is not particularly limited, and is appropriately about 95% by weight (for example, 99% by weight or more). It is. The silver purity is preferably 99.7% by weight or more, more preferably 99.9% by weight or more. Thus, by disposing high-purity silver on the surface of the conductive material, the diffuse reflectance is increased and the power generation efficiency is improved. The concentration of additive components (components other than silver such as selenium and antimony) on the surface of the conductive material is preferably about 0.3 wt% or less (preferably 0.1 wt% or less). The purity of silver and the concentration of components other than silver can be measured using an inductively coupled plasma mass spectrometer (ICP-MS) and an inductively coupled plasma emission spectrometer (ICP-AES). The same method can be adopted in the embodiments described later.

In another preferred embodiment, the conductive material is formed by hot-melt coating a metal material (typically an alloy) having a low melting point (for example, a melting point of 300 ° C. or lower, preferably 250 ° C. or lower). Specifically, a low-melting-point alloy (for example, “SnBi solder” manufactured by Arakawa Chemical Industries, Ltd.), melting point using a commercially available hot melt dispenser (for example, manufactured by Musashi Engineering Co., Ltd.) on the surface of a resin layer, a peelable support, or the like. 139 ° C.) can be applied to form a conductive material. Note that the same configuration as described above can be obtained by employing various printing methods such as screen printing.

When the conductive material is composed of a plurality of metal wires, the number of metal wires in the conductive material is 2 or more (typically 2 to 20, more preferably 4 to 12, more preferably 6 to 10). The plurality of metal wires are preferably arranged in parallel with a space between each other. The number of metal wires in the conductive material may be one. In the present specification, when the conductive material is composed of a plurality of metal wires, one of the metal wires may be regarded as the conductive material.

It is preferable that the ratio (H / W) of the height (H) to the width (W) (H / W) in the cross section orthogonal to the longitudinal direction of the conductive material is set to ½ or less. When the conductive material is composed of a plurality of metal wires, each metal wire has a ratio (H / W) of height (H) to width (W) in a cross section orthogonal to the longitudinal direction of 1 / H. It is preferably set to 2 or less. Thereby, excellent performance can be exhibited. The ratio (H / W) is preferably about 1/3 or less from the viewpoint of wiring workability and connection reliability, and preferably 1/5 or more (for example, 1/4 or more) from the viewpoint of power generation efficiency. It is. Moreover, when a electrically conductive material has a metal wire, it is preferable that a metal wire has a rectangular shape in the cross section orthogonal to the longitudinal direction. Thereby, almost the whole area of one surface of the metal wire can be in surface contact with the surface of the solar battery cell. The rectangular shape may be chamfered at each corner. Note that the cross-sectional shape of the metal wire is not limited to this, and may be a circular shape, an elliptical shape, a semicircular shape, a trapezoidal shape, a triangular shape, or the like. From the viewpoint of the contact area with the solar battery cell, the conductive material (typically a metal wire) preferably has a flat portion (typically a surface) in contact with the solar battery cell.

When the conductive material has a metal wire, the width of the metal wire (each width in the case of having a plurality of metal wires) is preferably 0.03 mm or more from the viewpoint of collecting current loss, strength, handling property, and workability. More preferably, it is 0.1 mm or more, More preferably, it is 0.2 mm or more. The width is preferably 1.5 mm or less, more preferably 1.2 mm or less, and further preferably 1.0 mm or less from the viewpoint of reducing shadow loss. In addition, the said width | variety points out the length (width | variety) orthogonal to the longitudinal direction of a metal wire.

Moreover, when arrange | positioning the several metal wire extended linearly at intervals, from the viewpoint of shadow loss reduction etc., the space | interval of a metal wire becomes like this. Preferably it is 0.1 cm or more, More preferably, it is 0.8 cm or more. More preferably 1.5 cm or more. The distance is preferably less than 4.0 cm, more preferably less than 3.0 cm, and even more preferably 2.5 cm or less from the viewpoint of reducing current collection loss. In addition, the said space | interval is a pitch and points out the distance between the centerlines in the width direction of a metal wire.

The thickness (height) of the conductive material is 0.01 to 1 mm (for example, 0.02 to 0.5 mm, typically 0.05 to 0.00 mm) from the viewpoints of conductivity, strength, handling properties, and workability. 3 mm) or so is preferable. When the conductive material has a metal wire, the thickness of the metal wire is preferably selected from the same range.

<< Wiring structure >>
FIG. 5 is a top view schematically showing a wiring structure according to an embodiment, and FIG. 6 is a cross-sectional view taken along line VI-VI of the wiring structure of FIG.

As illustrated in FIGS. 5 and 6, the wiring structure 1 includes a conductive portion 30, a first resin layer 50 disposed above the conductive portion 30, and a second resin layer 60 disposed below the conductive portion 30. And comprising. In addition, the wiring structure 1 has a first region 10 and a second region 12. The first region 10 and the second region 12 are regions corresponding to one and the other of two adjacent solar cells in the solar cell module, respectively. Specifically, when the solar cell module is constructed, the first region 10 is a region overlapping with one solar cell, and the second region 12 is a region overlapping with the other solar cell. In this embodiment, each of the first region 10 and the second region 12 is a region having a quadrangular shape when the wiring structure 1 is viewed from above, and is between the first region 10 and the second region 12. Is provided with a predetermined interval. The solar battery cell of this embodiment has a substantially square shape (approximately 15.5 cm × 15.5 cm), and the first region 10 and the second region 12 have the same shape and the same size.

The conductive part 30 has a continuous shape from the first region 10 to the second region 12. The conductive portion 30 is arranged so as to extend to almost both ends of the wiring structure 1 in the arrangement direction of the first region 10 and the second region 12 (which may also be the arrangement direction of solar cells). Further, the conductive portion 30 is partially disposed in the first region 10. The conductive portion 30 is also partially disposed in the second region 12.

As the conductive part 30, the above-mentioned conductive material for solar cell module is used. Therefore, the surface of the conductive portion 30 (at least the surface on the solar cell module light incident surface side, the same applies hereinafter) exhibits a diffuse reflectance of 60% or more. The diffuse reflectance is more preferably 80% or more, further preferably 85% or more, particularly preferably 87% or more, and particularly preferably 90% or more. Moreover, it is preferable that the diffuse reflection ratio in the surface of the electroconductive part 30 is 80% or more. The diffuse reflection ratio is more preferably 90% or more, further preferably 95% or more, and particularly preferably 99% or more. Furthermore, the arithmetic average roughness (Ra) of the surface of the conductive part 30 is preferably about 60 nm or more. The Ra is more preferably 70 nm or more, further preferably 80 nm or more (for example, 110 nm or more, further for example, 140 nm or more), and particularly preferably 200 nm or more (for example, 220 nm or more, further, for example, 250 nm or more). In particular, the surface of the conductive portion 30 is made of silver (typically a silver plating layer), the purity thereof is 99.7 wt% or more (preferably 99.9 wt% or more), and the silver film Ra of the said range is applied preferably with respect to the structure whose thickness is 1.0 micrometer or more (preferably 1.5 micrometers or more). About the structure and material of the electroconductive part 30, since the structure and material demonstrated with the electrically conductive material may be employ | adopted, the overlapping description is abbreviate | omitted. The surface of the conductive portion 30 is a surface facing the first resin layer 50 and / or the second resin layer 60. In that case, the first resin layer 50 and / or the second resin layer 60 facing the surface of the conductive portion 30 may be a transparent resin layer.

Specifically, the conductive portion 30 includes a plurality of metal wires 40 extending from the first region 10 to the second region 12. The plurality of metal wires 40 are arranged at intervals from each other along the arrangement direction of the first region 10 and the second region 12. The metal wires 40 are linearly arranged so as to be parallel to each other, and extend to almost both ends of the wiring structure 1 in the arrangement direction of the first region 10 and the second region 12. In other words, each metal wire 40 extends in a straight line from the outer end portion of the first resin layer 50 in the first region 10 to the outer end portion of the second resin layer 60.

The first resin layer 50 is disposed in the first region 10. The first resin layer 50 has substantially the same shape and size as the first region 10. In the first region 10, the first resin layer 50 is disposed above the conductive portion 30 (specifically, the metal wire 40). The upper surface of the first resin layer 50 constitutes a part of the outer surface (upper surface) of the wiring structure 1 (the upper surface of the first region 10). On the other hand, the lower surface of the first region 10 of the wiring structure 1 is constituted by the first resin layer 50 and the conductive portion 30. In this embodiment, the first resin layer 50 is a transparent pressure-sensitive adhesive layer, and the metal wire 40 is bonded to the surface of the first resin layer 50. In addition, the upper and lower sides of the wiring structure in the present specification correspond to the front and back of the solar battery cell described later, and thus correspond to the front and back (up and down) of the solar battery module. Depending on how the solar cell module is installed, the top and bottom may not necessarily be strictly up and down, so the top and bottom of the wiring structure is not limited to exact top and bottom, and is understood to indicate a relative positional relationship. The

The second resin layer 60 is disposed in the second region 12. The second resin layer 60 has substantially the same shape and size as the second region 12. In the second region 12, the second resin layer 60 is disposed below the conductive portion 30 (specifically, the metal wire 40). The lower surface of the second resin layer 60 constitutes a part of the outer surface (lower surface) of the wiring structure 1 (the lower surface of the second region 12). In this embodiment, the second resin layer 60 is a transparent pressure-sensitive adhesive layer, and the metal wire 40 is bonded to the surface of the second resin layer 60. In this embodiment, the upper surface of the second region 12 of the wiring structure 1 is constituted by the second resin layer 60 and the conductive portion 30. In addition, the 2nd resin layer 60 arrange | positioned at the back surface of a photovoltaic cell does not need to be transparent.

≪Wiring structure with release liner≫
FIG. 7 is a cross-sectional view corresponding to FIG. 6 and schematically showing a wiring structure with a release liner according to an embodiment.

The wiring structure 1 can be provided for manufacturing a solar cell module in a form protected by a release liner. As shown in FIG. 7, the wiring structure 2 with a release liner includes the wiring structure 1 and four release liners covering the upper and lower surfaces of the first region 10 and the upper and lower surfaces of the second region 12, respectively. A first release liner 70, a second release liner 72, a third release liner 74, and a fourth release liner 76 are provided. The first release liner 70 is disposed on the upper surface of the first resin layer 50 in the first region 10 of the wiring structure 1. The second release liner 72 is disposed on the lower surface of the conductive portion 30 in the first region 10. The third release liner 74 is disposed on the upper surface of the conductive portion 30 in the second region 12. The fourth release liner 76 is disposed on the lower surface of the second resin layer 60 in the second region 12. As described above, the wiring in the solar cell module is efficiently arranged by arranging the release liner so that it can be separated into the first region 10 and the second region 12 on each of the upper and lower surfaces of the wiring structure 1. Can be done well. This point will be described later. In this embodiment, as the release liners 70, 72, 74, and 76, a polyester resin film whose one side has been subjected to a release treatment is used.

The wiring structure 1 and the wiring structure 2 with a release liner as described above can be manufactured, for example, by the following method. First, the above-described conductive material is prepared as the conductive portion 30 (for example, a plurality of metal wires 40). Moreover, the 1st resin layer 50 and the 2nd resin layer 60 by which one side was protected by the release liner (For example, the 1st release liner 70 and the 4th release liner 76) are prepared, respectively. Then, the exposed surface (for example, the surface opposite to the surface protected by the first release liner 70) of the first resin layer 50 is fixed (for example, bonded) to a part of the conductive portion 30 (the portion that becomes the first region 10). ) Further, the exposed surface of the second resin layer 60 (for example, the surface opposite to the surface protected by the fourth release liner 76) is fixed to the other part of the conductive portion 30 (the portion that becomes the second region 12) ( For example, bonding). The second resin layer 60 is fixed to the surface of the conductive part 30 opposite to the side on which the first resin layer 50 is fixed. Thereafter, the second release liner 72 is bonded to the exposed surface of the first resin layer 50 in the portion that becomes the first region 10 and the conductive portion 30, and the exposed surface of the second resin layer 60 in the portion that becomes the second region. A third release liner 74 is bonded to the conductive portion 30. In this way, the wiring structure 1 and the wiring structure 2 with the release liner are manufactured. The timing of molding (processing into a predetermined shape) of the first resin layer 50 and the second resin layer 60 is not particularly limited, and the first resin layer 50 and the second resin layer 60 processed into a predetermined shape are prepared in advance. The first resin layer 50 and the second resin layer 60 may be fixed to the conductive portion 30, and then the first resin layer 50 and the second resin layer 60 may be formed in a predetermined shape. It is also possible to cut to size.

In a preferred embodiment, the long first resin layer 50 and the long second resin layer 60 are arranged in parallel (and horizontally, for example) at a predetermined interval, and the first resin layer 50 and the second resin layer 50 are arranged in parallel. From the direction intersecting (typically orthogonal) with the longitudinal direction of the resin layer 60, the conductive material described above as the conductive portion 30 (typically the metal wire 40) is disposed above the second resin layer 60 and the first resin layer. The wiring structure 1 is produced by inserting the first resin layer 50 and the second resin layer 60 in a direction intersecting (typically orthogonal) with their longitudinal directions. can do. In this case, the upper surface of the first resin layer 50 and the lower surface of the second resin layer 60 may typically be in a form protected by a release liner, respectively. Further, in the production of the wiring structure 1, the first resin layer 50 and the second resin layer 60 have a step (insertion space) when viewed from the side from the viewpoint of ease of insertion of the conductive portion 30. It is preferable to arrange in such a manner. For example, a roll of a long first resin layer 50 whose one surface is covered with a release liner and a roll of a long second resin layer 60 whose one surface is covered with a release liner are arranged side by side. The wiring structure 1 is continuously produced by arranging, drawing out the first resin layer 50 and the second resin layer 60 in parallel, sequentially inserting the conductive portions 30 therebetween, and cutting them at predetermined intervals. can do. When both the first resin layer 50 and the second resin layer 60 are pressure-sensitive adhesive layers, the conductive portion 30 is inserted into a predetermined position with respect to the first resin layer 50 and the second resin layer 60 and then appropriately By pressing at a proper timing, the conductive portion 30 can be satisfactorily fixed to the first resin layer 50 and the second resin layer 60.

≪Solar cell module wiring method≫
FIG. 8 is an explanatory diagram of a solar cell module wiring method according to an embodiment.

Next, wiring in the solar cell module 100 performed using the wiring structure 1 (which may be the wiring structure 2 with a release liner) will be described. As illustrated in FIG. 8, the solar battery cell 110 a is disposed below the first region 10 of the wiring structure 1, and the solar battery cell 110 b is disposed above the second region 12. When the lower surface of the first region 10 is covered with a release liner (for example, a second release liner), the release liner is peeled off from the lower surface of the first region 10 and the solar cell is formed on the conductive portion 30 of the first region 10. The front surface of the cell 110a is brought into contact. In addition, when the upper surface of the second region 12 is covered with a release liner (for example, a third release liner), the release liner is peeled off from the upper surface of the second region 12 to form the conductive portion 30 in the second region 12. The back surface of the solar battery cell 110b is brought into contact. Thereby, the upper surface of the solar battery cell 110 a and the lower surface of the solar battery cell 110 b are electrically connected by the conductive portion 30 of the wiring structure 1. And the upper surface of the 2nd area | region 12 of another wiring structure 1 is made to contact | abut to the lower surface of the photovoltaic cell 110a, and the lower surface of the 1st area | region 10 of another wiring structure 1 is made to contact the upper surface of the photovoltaic cell 110b. Abut. By repeating this operation by applying it to other solar cells (for example, solar cells 110c and 110d), the vertical wiring of the plurality of solar cells 110a, 110b, 110c and 110d as shown in FIG. 1 is completed. To do. The conduction by the contact does not require joining by an adhesive means such as solder. Moreover, since the upper and lower wirings of the two solar cells are realized only by arranging the wiring structure therebetween, the wiring workability is excellent. The contact state of the conductive portion to the solar battery cell having the above configuration has a high degree of freedom compared to a fixing method such as solder bonding, and thus has excellent impact resistance. Further, in this embodiment, since the first resin layer 50 and the second resin layer 60 are adhesive layers having adhesiveness, the conductive portion 30 partially disposed in the first region 10 and the second region 12. It adheres to the solar cells 110a and 110b through (specifically, the metal wire 40). Therefore, a separate bonding means such as a conductive adhesive is not necessary, and the wiring workability is excellent also in this respect.

The solar cell group (wired solar cell group) 120 to which the wiring structure 1 is attached as described above is sandwiched between two sheet-like sealing resins, and the surface covering member 160 and the back surface are further provided outside thereof. By disposing the covering member 170, the solar cell module 100 in which the plurality of solar cells 110a, 110b, 110c, and 110d are built in a state in which they are conducted is constructed. The two sheet-shaped sealing resins are sandwiched between the front surface covering member 160 and the back surface covering member 170, and further attached with a frame (not shown), and then heat-cured to integrate them into the sealing shown in FIG. The stop resin 150 is obtained. In the solar cell module 100 obtained in this way, the sealing resin 150 is provided between the front surface covering member 160 constituting the front (front) surface of the solar cell module 100 and the rear surface covering member 170 constituting the back surface. The solar cell group (wiring solar cell group) 120 to which the wiring structure 1 is attached is housed in a state covered with the solar cell.

In the solar cell module according to the above-described embodiment, the conductive portion that electrically connects two adjacent solar cells among the plurality of solar cells is one of the adjacent two solar cells. However, the technology disclosed here is not limited to this. By applying the technology disclosed herein to various solar cell modules in which at least a part of the conductive portion is arranged on the light incident surface side of the solar cell module, it is possible to obtain the power generation efficiency improvement effect. For example, the solar cell module may be one in which a solar cell is sandwiched from above and below by a conductive portion formed in advance and the upper and lower conductive portions are conducted between the cells. Moreover, a solar cell module may join a conductive part individually to a photovoltaic cell using solder etc.

Further, the conductive part is not limited to the shape, structure, etc. of the above embodiment. The conductive portion can employ various shapes, structures, and the like that can realize electrical connection of solar cells. The conductive portion of the above embodiment is a plurality of metal wires that extend linearly and are arranged in parallel to each other, but the metal wires may extend in a curved shape. In the case of having a plurality of metal wires, the plurality of metal wires may be separated from each other, may be in contact with each other, or may be non-parallel to each other (for example, may be crossed or not parallel to each other) ).

Moreover, the electroconductive part in the lower surface (back surface) of a photovoltaic cell does not need to have a fine wire shape like a metal wire, for example, may have a quadrangular shape which covers the whole back surface of a photovoltaic cell. . In other words, the conductive portion uses a metal wire as a portion located on the front (front) surface side of one solar cell, and a portion located on the back side of the other solar cell as the solar cell. It is good also as a conductive sheet of substantially the same shape (for example, a metal sheet such as a rectangular copper foil). In this case, the conductive portion may have a shape in which a striped portion and a quadrangular portion made of a plurality of metal wires are continuous.

In the above embodiment, the first resin layer and the second resin layer are provided, but the first resin layer and the second resin layer may not be provided. In that case, the conductive portion can be in direct contact with the sealing resin. Also, when the first resin layer and the second resin layer are provided, the shape is not limited to the shape of the above embodiment (a rectangular shape that is substantially the same shape as the solar cell), and the shape of the solar cell. Various shapes can be taken according to the above. Furthermore, the first resin layer and the second resin layer may be made of the same material (same composition) or may be made of different materials (having different compositions). For example, when the solar battery cell is a single-sided light receiving type, only the first resin layer is a transparent resin layer (preferably has a total light transmittance greater than or equal to a predetermined value described later), and the second resin layer is transparent. The non-transparent resin layer which does not have may be sufficient. In that case, the second resin layer specifically has a total light transmittance described below of less than 70% (for example, less than 50%, typically less than 30%). Therefore, the first resin layer and the second resin layer may have different total light transmittance. Or when a photovoltaic cell is a double-sided light reception type, it is preferable that both the 1st resin layer and the 2nd resin layer are transparent resin layers, and it is more preferable to have the total light transmittance more than the predetermined mentioned later. In addition, when the electroconductive part arrange | positioned at the back surface side of a photovoltaic cell is a conductive sheet, the 2nd resin layer does not need to be.

In addition, the solar cells arranged in one solar cell module are usually 5 or more (for example, 10 or more, typically 30 or more), and typically 50 or more (50 to 70). . The number of wiring structures per row composed of a plurality of solar cells can basically be a number obtained by subtracting 1 from the number of solar cells. In the solar cells located at both ends of the solar cell group, conductive portions connected to extraction electrodes (terminal bars) (not shown) can be arranged on the front surface or the back surface. Moreover, in the said embodiment, although the several photovoltaic cell has shown only the photovoltaic cell group arranged in a row, the arrangement | sequence (arrangement | positioning) of several photovoltaic cell is not limited to this, A linear form, curved form , Regular patterns or irregular patterns. Moreover, the space | interval of a photovoltaic cell does not need to be constant.

≪Components of solar cell module and wiring structure≫
About the electroconductive part (conductive material) which comprises a solar cell module, it is as above-mentioned, Other elements (for example, 1st resin layer, 2nd resin layer) which can comprise a solar cell module and a wiring structure, The present invention is not limited to the above-described embodiment, and various modifications can be made within the range where the effects of the invention are exhibited. Hereinafter, each element which comprises a solar cell module and a wiring structure is demonstrated.

<First resin layer and second resin layer>
(Resin layer characteristics)
The first resin layer and the second resin layer (hereinafter collectively referred to as “resin layer”) disclosed herein can function as layers that favorably maintain the contact state between the solar battery cell and the conductive portion. Typically, the resin layer is preferably a layer that exhibits the properties of an elastic body or a viscoelastic body in a temperature range near room temperature. The viscoelastic body referred to here is a material having both properties of viscosity and elasticity, that is, a material having a property that satisfies the phase of the complex elastic modulus exceeding 0 and less than π / 2 (typically at 25 ° C. A material having the above properties). The resin layer preferably has an insulating property.

The storage elastic modulus G ′ (frequency 1 Hz, strain 0.1%, 150 ° C.) of the resin layer disclosed herein is preferably 5,000 Pa or more. By using a resin layer exhibiting a storage elastic modulus G ′ of a predetermined value or higher at high temperature, the solar cell and the conductive part are in good contact under high temperature conditions, and under various conditions (for example, wide temperature conditions), The contact state can be stably maintained. The resin layer more preferably satisfies tan δ described later in addition to the storage elastic modulus G ′. For example, when the conductive part is pressed against the solar battery cell from the outside of the resin layer when constructing the solar battery module, the conductive part can be brought into good contact with the surface of the solar battery cell even under high temperature conditions. The 150 ° C. storage elastic modulus G ′ is more preferably 10,000 Pa or more, further preferably 20,000 Pa or more, particularly preferably 25,000 Pa or more (for example, 50,000 Pa or more, typically 80,000 Pa or more). is there. The 150 ° C. storage elastic modulus G ′ is usually 1,000,000 Pa or less, preferably 500,000 Pa or less, more preferably 200,000 Pa or less (for example, 150,000 Pa or less, typically 100,000 or less). 000 Pa or less).

The storage elastic modulus G ′ (frequency 1 Hz, strain 0.1%) of the resin layer is preferably in the range of 5,000 Pa to 1,000,000 Pa in the temperature range of 80 ° C. to 150 ° C. That the change in the storage elastic modulus G ′ in the high temperature range is within a predetermined range may mean that the physical properties of the resin layer are not easily affected by the temperature change. The storage elastic modulus G ′ of the resin layer in the temperature range of 80 ° C. to 150 ° C. is more preferably 5,000 Pa to 500,000 Pa, still more preferably 5,000 Pa to 200,000 Pa (for example, 10,000 Pa to 100,000 Pa). Is within the range.

Furthermore, the storage elastic modulus G ′ (frequency 1 Hz, strain 0.1%) of the resin layer is preferably in the range of 5,000 Pa to 10,000,000 Pa in the temperature range of 30 ° C. to 150 ° C. The change in the storage elastic modulus G ′ within the wide temperature range as described above being within a predetermined range may mean that the physical properties of the resin layer are not easily affected by the temperature change. The storage elastic modulus G ′ of the resin layer in the temperature range of 30 ° C. to 150 ° C. is more preferably 5,000 Pa to 1,000,000 Pa, still more preferably 5,000 Pa to 500,000 Pa (for example, 10,000 Pa to 200, 000 Pa).

Also, the maximum value of tan δ of the resin layer disclosed herein is preferably less than 0.4 in the temperature range of 80 ° C. to 150 ° C. By using a resin layer having a tan δ of a predetermined value or less in a high temperature region, the solar battery cell and the conductive part are in good contact in the high temperature region, and the contact state is various under various conditions (for example, a wide temperature condition). It can be stably maintained. For example, when the conductive part is pressed against the solar battery cell from the outside of the resin layer when constructing the solar battery module, the conductive part can be brought into good contact with the surface of the solar battery cell even under high temperature conditions. Here, tan δ is a value (G ″ / G ′) obtained from loss elastic modulus G ″ / storage elastic modulus G ′. The maximum value of tan δ of the resin layer in the temperature range of 80 ° C. to 150 ° C. is more preferably less than 0.3. In addition, the minimum value of tan δ in the above temperature range can be usually 0.01 or more (for example, 0.1 or more).

The storage elastic modulus G ′ (frequency 1 Hz, strain 0.1%, 150 ° C.) and tan δ (G ″ / G ′) and tan δ (G ″ / G ′) of the resin layer are commercially available rheometers (for example, device name “ARES 2KFRT”, TA Instruments). Measured by a specified temperature range (a temperature range including 80 ° C to 150 ° C, and a temperature range including 30 ° C to 150 ° C) under the conditions of a frequency of 1 Hz and a strain of 0.1%. Good. What is necessary is just to set a measurement temperature range and a temperature increase rate appropriately according to the model etc. of a measuring apparatus. For example, a temperature range of 30 ° C. to 160 ° C. and a temperature increase rate of about 0.5 ° C. to 20 ° C./min (for example, 10 ° C./min) can be achieved. As a measurement sample, it is desirable to use a resin layer having a thickness of about 2 mm punched out to a diameter of about 8 mm.

The resin layer may or may not have adhesiveness (typically adhesiveness). In other words, the resin layer may be an adhesive layer or a non-adhesive layer. Here, the “adhesive layer” refers to a SUS304 stainless steel plate as an adherend in accordance with JIS Z 0237: 2009, and a 2 kg roller is reciprocated once in a measurement environment at 23 ° C. to be bonded to the adherend. 30 minutes later, the peel strength when peeled in the direction of 180 ° at a pulling speed of 300 mm / min is 0.1 N / 20 mm or more. The “non-adhesive layer” refers to a layer that does not correspond to the adhesive layer, and typically refers to a layer having a peel strength of less than 0.1 N / 20 mm. The layer that does not stick to the stainless steel plate when the 2 kg roller is reciprocated once in a measurement environment of 23 ° C. and pressed against the SUS304 stainless steel plate is a non-adhesive layer here. This is a typical example included in the concept.

The technique disclosed here is preferably implemented in a form including a resin layer corresponding to an adhesive layer (also referred to as an adhesive layer) formed from an adhesive. In this case, the resin layer forming composition may be a pressure-sensitive adhesive composition. In the present specification, the “pressure-sensitive adhesive” refers to a material that exhibits a soft solid (viscoelastic body) state in a temperature range near room temperature and has a property of easily adhering to an adherend by pressure. The adhesive here is generally complex elastic modulus E ^* (1 Hz) as defined in “C. A. Dahlquist,“ Adhesion: Fundamental and Practice ”, McLaren & Sons, (1966) P. 143”. <10 < ⁷ > dyne / cm < ² > material (typically a material having the above properties at 25 [deg.] C.).

It is preferable that the surface of the resin layer has adhesiveness. As a result, the conductive portion is satisfactorily fixed to the resin layer. Moreover, the conductive part non-arrangement region on the surface of the resin layer adheres well to the solar battery cell when the solar battery module is constructed. By using a resin layer having adhesiveness on both surfaces, the sealing resin and the conductive portion can be fixed satisfactorily. In addition, when the surface of the resin layer is weakly adhesive or substantially non-adhesive, the conductive portion and the solar battery cell may be fixed to the resin layer using a known adhesive, pressure-sensitive adhesive, or the like. .

In a preferred embodiment, the surface of the resin layer exhibits a 180-degree peel strength (adhesive power to solar cell) of 3N / 10 mm or more with respect to the crystalline Si solar cell. From the viewpoint of fixing to the solar battery cell or the conductive part, the adhesive strength to the solar battery cell is more preferably 5 N / 10 mm or more, further preferably 8 N / 10 mm or more (for example, 10 N / 10 mm or more, typically 12 N). / 10 mm or more). In a particularly preferred embodiment, the surface of the resin layer exhibits a 180-degree peel strength of 15 N / 10 mm or more with respect to the crystalline Si solar battery cell. The upper limit of the adhesive force to the solar cell on the surface of the resin layer is not particularly limited, but the above adhesive force is usually 50 N / 10 mm or less (for example, 30 N / 10 mm or less, typically from the viewpoint of workability such as reattachment). 20N / 10 mm or less).

The adherend used for the measurement of the adhesion to solar cells is a crystalline Si solar cell. For example, a crystalline Si solar battery cell manufactured by Q CELLS, a single crystalline Si cell manufactured by GINTECH, or a polycrystalline Si cell is preferably used. For measurement, after the resin layer is firmly bonded to the adherend by laminating or the like, using a commercially available tensile tester (for example, “Autograph AGS-J”, manufactured by Shimadzu Corporation) at 23 ° C., 50 It can be carried out in an atmosphere of% RH under the conditions of a tensile speed of 30 mm / min and a peeling angle of 180 degrees.

The resin layer typically has translucency. The resin layer which concerns on a preferable one aspect | mode is a transparent resin layer (for example, transparent adhesive layer). In this specification, the transparent resin layer refers to a resin layer having a total light transmittance of 70% or more. From the viewpoint of power generation efficiency of the solar battery cell, the total light transmittance of the resin layer is more preferably 85% or more, and further preferably 90% or more. The total light transmittance of the resin layer can be measured using a commercially available haze meter (for example, trade name “HR-100”, manufactured by Murakami Color Research Laboratory Co., Ltd.).

The resin layer disclosed herein is preferably composed of a resin material having a melt mass flow rate (MFR) at 150 ° C. of 9 g / 10 min or less. The resin layer exhibiting the MFR can exhibit good shape stability. The MFR is more preferably 3 g / 10 min or less, further preferably 1 g / 10 min or less, and particularly preferably 0.5 g / 10 min or less (for example, 0.2 g / 10 min or less). The above MFR measurement is based on JIS K 7210: 1999 or ASTM D 1238, and the amount of resin flowing out at a constant time under conditions of a temperature of 190 ° C. and a load of 2.16 Kg is weighed with a balance and unit time (10 minutes) This may be done by calculating the amount of resin discharged.

The linear expansion coefficient of the resin layer is preferably less than 15% in the temperature range of −40 ° C. to 85 ° C. According to the resin layer exhibiting the above linear expansion coefficient, a wiring with further improved durability is realized. The linear expansion coefficient is more preferably 12% or less (for example, 10% or less). As the linear expansion coefficient of the resin layer, either one (preferably both) values of the tensile mode and the compression mode measured by the following method are adopted.
[Linear expansion coefficient]
(Tensile mode)
Each resin layer is cut into a size of 10 mm in length × about 0.5 mm ² in cross-sectional area to produce a test piece. Using this test piece, a line at −40 ° C. to 85 ° C. under the conditions of a tensile load of 20 mN and a temperature increase rate of 1.7 ° C./min using a thermal analyzer (trade name “EXSTAR6000”, manufactured by Seiko Instruments Inc.) The expansion rate (%) is measured. The linear expansion coefficient is obtained from the following equation.
Linear expansion coefficient (%) at −40 ° C. to 85 ° C. = (AB) / B × 100
A: Maximum length of test piece at −40 ° C. to 85 ° C. (mm)
B: Minimum value of length of test piece at −40 ° C. to 85 ° C. (mm)
(Compression mode)
Each resin layer is cut into a size of about 5 mm square to produce a test piece. Using this test piece, a linear expansion coefficient (%) at −40 ° C. to 85 ° C. under the following conditions using a TMA (Thermal Mechanical Analysis) device (device name “TMA / SS7100”, manufactured by SII Nano Technology) Measure. The linear expansion coefficient is obtained from the following equation.
Linear expansion coefficient (%) at −40 ° C. to 85 ° C. = (AB) / B × 100
A: Maximum thickness of test piece at −40 ° C. to 85 ° C. (μm)
B: Minimum thickness of specimen at -40 ° C to 85 ° C (μm)
Measurement condition:
Load during indentation test: 9.8 mN
Probe diameter: φ3.5mm
Temperature program; −60 ° C. → 160 ° C., 10 ° C./min Measurement atmosphere; N ₂ (flow rate 200 mL / min)

(Composition of resin layer)
The resin layer disclosed here is a resin layer formed from a resin material. A resin layer containing a crosslinked resin as a base polymer (for example, a resin layer subjected to crosslinking treatment) is preferable. The resin layer has physical properties different from those of the sealing resin, and can typically be formed from a resin material different from the resin material of the sealing resin. The resin that forms the resin layer is an acrylic resin, EVA resin, polyolefin resin, rubber, silicone resin, polyester resin, urethane resin, polyether resin, polyamide resin, fluorine resin, etc. 1 type or 2 types or more selected from these resin. The acrylic resin is an acrylic polymer as a base polymer (the main component of the polymer component, that is, the component having the largest blending ratio in the polymer component, typically a component that exceeds 50% by weight). The resin material. The same meaning applies to EVA and other resins.

(EVA resin)
The resin layer according to a preferred embodiment is an EVA resin layer formed from an EVA resin. The proportion of EVA in the resin layer (which may also be a resin layer forming composition) is not particularly limited, but is typically 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight. That's it. The EVA resin layer is subjected to a thermosetting treatment at about 80 to 200 ° C. (eg, 100 to 180 ° C., typically 120 to 160 ° C.) from the viewpoint of obtaining desired physical properties. Is preferred. The heat curing treatment time is not particularly limited and is usually 5 minutes or longer, preferably 10 minutes or longer, more preferably 20 minutes or longer (for example, 30 minutes or longer, typically 40 minutes to 120 minutes). The EVA resin layer is preferably subjected to a press treatment before or during the thermosetting treatment.

(Acrylic polymer)
In a preferred embodiment, the resin layer may be a layer containing an acrylic polymer as a base polymer, that is, an acrylic resin layer. A resin layer having such a composition is preferable because it can be easily adjusted to desired physical properties such as shape stability and flexibility. The proportion of the acrylic polymer in the resin layer is not particularly limited, but is typically 50% by weight or more, preferably 70% by weight or more, and more preferably 80% by weight or more.
In the present specification, “(meth) acrylate” means acrylate and methacrylate comprehensively. Similarly, “(meth) acryloyl” means acryloyl and methacryloyl, and “(meth) acryl” generically means acrylic and methacryl.
Further, in this specification, the “monomer component constituting the acrylic polymer” refers to a monomer unit constituting the acrylic polymer in the resin material forming the resin layer. The monomer component may be contained in the resin layer forming composition used for forming the resin layer in an unpolymerized form (that is, in the form of a raw material monomer in which the polymerizable functional group is unreacted). , May be included in the form of a polymer, or may be included in both forms.

The resin layer forming composition disclosed herein preferably contains the component (A) as a monomer component constituting the acrylic polymer.

The component (A) is an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms at the ester end. Hereinafter, an alkyl (meth) acrylate having an alkyl group having a carbon number of X or more and Y or less at the ester end may be referred to as “C _XY alkyl (meth) acrylate”. The structure of the C _1-20 alkyl group in the C _1-20 alkyl (meth) acrylate is not particularly limited, and either a linear or branched alkyl group can be used. As the component (A), one kind of such C _1-20 alkyl (meth) acrylate can be used alone or in combination of two or more kinds.

_{Examples of} C _1-20 alkyl (meth) acrylates having a linear alkyl group at the ester end include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, n- Pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, n-decyl (meth) acrylate, n-undecyl (Meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, n-pentadecyl (meth) acrylate, n-hexadecyl (meth) acrylate, n-heptadecyl (meta) ) Acrylate, n- Examples include octadecyl (meth) acrylate, n-nonadecyl (meth) acrylate, and n-eicosyl (meth) acrylate. Further, as C _3-20 alkyl (meth) acrylate having a branched alkyl group at the ester terminal, isopropyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, isopentyl (meth) acrylate, t- Pentyl (meth) acrylate, neopentyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) Acrylate, 2-propylheptyl (meth) acrylate, isoundecyl (meth) acrylate, isododecyl (meth) acrylate, isotridecyl (meth) acrylate, isomistyryl (meth) Examples include acrylate, isopentadecyl (meth) acrylate, isohexadecyl (meth) acrylate, isoheptadecyl (meth) acrylate, isostearyl (meth) acrylate, isononadecyl (meth) acrylate, and isoeicosyl (meth) acrylate. These alkyl (meth) acrylates can be used alone or in combination of two or more.

The component (A) can be preferably implemented in an embodiment containing C _4-9 alkyl (meth) acrylate as the component (A1). When the acrylic polymer contains the component (A1) as a monomer unit, a resin layer having desired physical properties tends to be easily obtained, and tackiness tends to be easily obtained. The component (A1) may be one or more selected from C _4-9 alkyl (meth) acrylates. From the viewpoint of compatibility with other monomer components (for example, cyclic nitrogen-containing monomers), C _4-9 alkyl acrylate is preferably used as component (A1). Preferable examples of C _4-9 alkyl acrylate include n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate and isononyl acrylate.

When the component (A) includes the component (A1), the proportion of the component (A1) in the component (A) is usually 20% by weight or more (eg 20 to 80% by weight), preferably 30% by weight or more. (For example, 30 to 70% by weight), more preferably 40% by weight or more (for example, 40 to 60% by weight). The proportion of the component (A1) in the component (A) may be 50% by weight or more (for example, 80% by weight or more, typically 90 to 100% by weight).

Further, the embodiment in which the component (A) includes C _10-18 alkyl (meth) acrylate as the component (A2) can be preferably carried out. When the acrylic polymer contains the component (A2) as a monomer unit, a resin layer having desired physical properties tends to be more easily obtained. The component (A2) may be one or more selected from C _10-18 alkyl (meth) acrylates. The component (A2) preferably contains a C _10-18 alkyl (meth) acrylate in which the alkyl group is a branched chain, and more preferably from the viewpoint of compatibility with other monomer components (for example, a cyclic nitrogen-containing monomer). From _C10-18 alkyl acrylates in which the alkyl group is branched. Preferable examples of the C _10-18 alkyl (meth) acrylate include isodecyl acrylate, isodecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, isomistyryl acrylate, isostearyl acrylate and stearyl methacrylate.

When the component (A) includes the component (A2), the proportion of the component (A2) in the component (A) is usually 20% by weight or more (for example, 20 to 80% by weight), preferably 30% by weight or more. (For example, 30 to 70% by weight), more preferably 40% by weight or more (for example, 40 to 60% by weight). The proportion of the component (A2) in the component (A) may be 50% by weight or more (for example, 80% by weight or more, typically 90 to 100% by weight).

When the component (A1) and the component (A2) are used in combination as the component (A), the weight ratio (A1: A2) of the component (A1) to the component (A2) is not particularly limited. The ratio is suitably 9 to 9: 1, and preferably 2: 8 to 8: 2 (eg, 3: 7 to 7: 3, typically 4: 6 to 6: 4).

The component (A) may contain one or more of C _1-3 alkyl (meth) acrylate and C _19-20 alkyl (meth) acrylate as the component (A3). When the component (A) includes the component (A3), from the viewpoint of the physical properties of the resin layer, the proportion of the component (A3) in the component (A) is usually 30% by weight or less (for example, 15% by weight or less, typically 1 to 5% by weight) is preferable. The technique disclosed here is an embodiment in which the component (A) does not substantially contain the component (A3) (the proportion of the component (A3) in the component (A) is less than 1% by weight, and further 0.1% by weight. In an embodiment that is less than).

The proportion of the component (A) in the monomer component is not particularly limited. From the viewpoint of physical properties of the resin layer and adhesive properties such as adhesive strength, the proportion of the component (A) is usually suitably 30% by weight or more, preferably 50% by weight or more, more preferably 60%. % By weight or more (eg, 75% by weight or more). In addition, the upper limit of the proportion of the component (A) is suitably about 98% by weight or less from the viewpoint of sufficiently obtaining the effects of the later-described components (B) and (C), and is 95% by weight. It is preferable that the amount be less than or equal to (for example, 90% by weight or less, typically 85% by weight or less).

In a preferred embodiment, the resin layer forming composition contains a component (B) as a monomer component constituting the acrylic polymer. The component (B) is a heterocycle-containing monomer such as a cyclic nitrogen-containing monomer or a cyclic ether group-containing monomer. The component (B) can advantageously contribute to improving the shape stability and transparency of the resin layer. The heterocyclic ring-containing monomer can be used alone or in combination of two or more.

As the cyclic nitrogen-containing monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a cyclic nitrogen structure can be used without particular limitation. The cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure. Examples of cyclic nitrogen-containing monomers include lactam vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2- Oxazoline group-containing monomers such as oxazoline and 2-isopropenyl-2-oxazoline; vinyl-based compounds having nitrogen-containing heterocycles such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, and vinylmorpholine And monomers. Moreover, the (meth) acryl monomer containing nitrogen-containing heterocyclic rings, such as a morpholine ring, a piperidine ring, a pyrrolidine ring, a piperazine ring, an aziridine ring, is mentioned. Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine, N-acryloylaziridine and the like. Among the cyclic nitrogen-containing monomers, lactam vinyl monomers are preferable and N-vinylpyrrolidone is more preferable from the viewpoint of cohesiveness and the like.

As the monomer having a cyclic ether group, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and a cyclic ether group such as an epoxy group or an oxetane group. It can be used without particular limitation. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and the like. Examples of the oxetane group-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-oxetanylmethyl (meth) acrylate, 3-ethyl-oxetanylmethyl (meth) acrylate, and 3-butyl-oxetanylmethyl (meth) acrylate. , 3-hexyl-oxetanylmethyl (meth) acrylate, and the like.

From the viewpoint of the physical properties of the resin layer, the proportion of the component (B) in the monomer component is usually 0.5% by weight or more, preferably 1% by weight or more, more preferably 3% by weight. More preferably, it is 10% by weight or more (for example, 12% by weight or more). The proportion of the component (B) is suitably about 50% by weight or less, preferably 40% by weight or less (for example, 30% by weight or less), from the viewpoint of sufficiently obtaining the effect of containing the component (A). , Typically 25% by weight or less).

In a preferred embodiment, the resin layer forming composition includes a component (C) as a monomer component constituting the acrylic polymer. The component (C) is a monomer having at least one of a hydroxy group and a carboxy group.

As the hydroxy group-containing monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a hydroxy group can be used without particular limitation. Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl ( Hydroxyalkyl (meth) acrylates such as (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate; -Hydroxyalkylcycloalkane (meth) acrylates such as -hydroxymethylcyclohexyl) methyl (meth) acrylate. Other examples include hydroxyethyl (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and the like. These can be used alone or in combination of two or more. Of these, hydroxyalkyl (meth) acrylate is preferred. For example, a hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 2 to 6 carbon atoms can be preferably used. Of these, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are more preferable.

As the carboxy group-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a carboxy group can be used without particular limitation. Examples of carboxy group-containing monomers include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate; itaconic acid, maleic acid, fumaric acid, And ethylenically unsaturated dicarboxylic acids such as citraconic acid; metal salts thereof (for example, alkali metal salts); anhydrides of the above ethylenically unsaturated dicarboxylic acids such as maleic anhydride and itaconic anhydride. These can be used alone or in combination of two or more. Among these, acrylic acid and methacrylic acid are preferable.

The technique disclosed herein can be preferably implemented in a mode in which the component (C) includes a hydroxy group-containing monomer. That is, it is preferable that the component (C) includes only a hydroxy group-containing monomer or includes a hydroxy group-containing monomer and a carboxy group-containing monomer. By increasing the proportion of the hydroxy group-containing monomer in the component (C), metal corrosion caused by the carboxy group can be reduced. From this, the technique disclosed here can be preferably implemented in a mode in which the monomer component does not substantially contain a carboxy group-containing monomer. For example, the proportion of the carboxy group-containing monomer in the monomer component can be less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.2% by weight.

The proportion of the component (C) in the monomer component is usually suitably 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 0, from the viewpoint of the physical properties of the resin layer. .8% by weight or more. The proportion of the component (C) may be 3% by weight or more, or 5% by weight or more (for example, 8% by weight or more, typically 10% by weight or more). The proportion of the component (C) is suitably about 35% by weight or less, preferably 30% by weight or less, more preferably 25% by weight or less (typically 5% by weight or less, eg 3 % By weight or less).

In a particularly preferred embodiment, the monomer component constituting the acrylic polymer includes all the components (A), (B), and (C). In that case, when the total amount of the above components (A), (B) and (C) is 100% by weight, the proportion of component (A) is 50 to 99% by weight (more preferably 60 to 95% by weight, still more preferably Is preferably 70 to 85% by weight, and the proportion of component (B) is 0.9 to 49.9% by weight (more preferably 4.5 to 39.5% by weight, still more preferably 14.2 to 29.2% by weight), and the proportion of component (C) is 0.1 to 35% by weight (more preferably 0.5 to 30% by weight, still more preferably 0.8 to 25% by weight). It is preferable to do.

The constituent monomer component in the technique disclosed herein may contain a monomer other than the components (A), (B) and (C) (hereinafter also referred to as “optional monomer”) as necessary.

Examples of the optional monomer include a monomer containing a functional group other than a hydroxy group and a carboxy group. Such a functional group-containing monomer can be used for the purpose of introducing a crosslinking point into the acrylic polymer or increasing the cohesive strength of the acrylic polymer. Examples of the functional group-containing monomer include amide group-containing monomers such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, and N-methylol (meth) acrylamide; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; For example, sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid; for example, phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; Keto group-containing monomers such as acrylamide, diacetone (meth) acrylate, vinyl methyl ketone, vinyl acetoacetate; for example, isocyanate group-containing monomers such as 2- (meth) acryloyloxyethyl isocyanate; For example, alkoxy group-containing monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; for example, alkoxysilyl groups such as 3- (meth) acryloxypropyltrimethoxysilane and 3- (meth) acryloxypropyltriethoxysilane Containing monomer; and the like. These can be used alone or in combination of two or more.

Other examples of the optional monomer include alicyclic monomers. As the alicyclic monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having an alicyclic structure-containing group can be used without particular limitation. it can. Here, the “alicyclic structure-containing group” refers to a portion containing at least one alicyclic structure. The “alicyclic structure” refers to a saturated or unsaturated carbocyclic structure having no aromaticity. In the present specification, the alicyclic structure-containing group is sometimes simply referred to as “alicyclic group”. Preferable examples of the alicyclic group include a hydrocarbon group and a hydrocarbon oxy group containing an alicyclic structure.

Examples of preferred alicyclic monomers include alicyclic (meth) acrylates having an alicyclic group and a (meth) acryloyl group. Specific examples of the alicyclic (meth) acrylate include cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth). Examples include acrylate, isobornyl (meth) acrylate, and dicyclopentanyl (meth) acrylate. These can be used alone or in combination of two or more.

The monomer component in the technology disclosed herein can be copolymerized with the above components (A), (B), and (C) as the above arbitrary monomer for the purpose of adjusting Tg of acrylic polymer and improving cohesion. In addition, a copolymerizable monomer other than those exemplified above may be included. Examples of such copolymerizable monomers include carboxylic acid vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), vinyltoluene; ) Aromatic ring-containing acrylate (eg phenyl (meth) acrylate), aryloxyalkyl (meth) acrylate (eg phenoxyethyl (meth) acrylate), arylalkyl (meth) acrylate (eg benzyl (meth) acrylate) ( (Meth) acrylates; olefinic monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; for example, methyl vinyl ether, ethyl vinyl ether, and the like Vinyl ether monomers; other, macromonomers, and the like having a radical polymerizable vinyl group in the monomer ends obtained by polymerizing a vinyl group. These can be used alone or in combination of two or more.

The amount of these optional monomers used is not particularly limited and can be determined as appropriate. Usually, the total amount of the arbitrary monomers used is suitably less than 50% by weight of the monomer component, preferably 30% by weight or less, and more preferably 20% by weight or less. The technique disclosed here can be preferably implemented in an embodiment in which the total amount of any monomer used is 10% by weight or less (for example, 5% by weight or less) of the monomer component. The technique disclosed here is an embodiment in which an optional monomer is not substantially used (for example, an embodiment in which the amount of the optional monomer used is 0.3% by weight or less, typically 0.1% by weight or less) of the monomer component. However, it can be preferably implemented.

The above-described component (A), component (B), component (C) and optional monomer are typically monofunctional monomers. In addition to such a monofunctional monomer, the monomer component in the technique disclosed herein can contain a polyfunctional monomer as necessary for the purpose of adjusting the cohesive force of the resin layer. Here, the monofunctional monomer in this specification refers to a monomer having one polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and a polyfunctional monomer. As described later, refers to a monomer having at least two polymerizable functional groups.

The polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group. Examples of polyfunctional monomers include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, penta Erythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methanetri (meth) ) Of acrylate, esters of polyhydric alcohols and (meth) acrylic acid; allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate. A polyfunctional monomer can be used individually by 1 type or in combination of 2 or more types. Among these, trimethylolpropane tri (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate can be preferably used. From the viewpoint of reactivity and the like, a polyfunctional monomer having two or more acryloyl groups is usually preferable.

The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, and the like, but is preferably 3% by weight or less of the above monomer component from the viewpoint of balancing cohesion and adhesion in a balanced manner. Is more preferable, and 1% by weight or less (for example, 0.5% by weight or less) is more preferable. Moreover, the lower limit of the usage-amount in the case of using a polyfunctional monomer should just be larger than 0 weight%, and is not specifically limited. Usually, the effect of improving the cohesive force can be appropriately exhibited by setting the amount of the polyfunctional monomer used to 0.001% by weight or more (for example, 0.01% by weight or more) of the monomer component.

Although not particularly limited, the proportion of the total amount of the component (A), the component (B) and the component (C) in the monomer component is typically more than 50% by weight, preferably 70% by weight. Above, more preferably 80% by weight or more, still more preferably 90% by weight or more. The technique disclosed here can be preferably implemented in an embodiment in which the ratio of the total amount is 95% by weight or more (for example, 99% by weight or more). The technology disclosed herein can be preferably implemented in an embodiment in which the ratio of the total amount in the monomer components is 99.999% by weight or less (for example, 99.99% by weight or less).

Although not particularly limited, the Tg of the polymer corresponding to the composition of the monomer component is preferably −20 ° C. or less, preferably −25 ° C. or less, from the viewpoints of physical properties and adhesiveness of the resin layer. More preferably -80 ° C or higher, preferably -60 ° C or higher, -50 ° C or higher (eg -40 ° C or higher, typically -35 ° C or higher). It is more preferable.

Here, the Tg of the polymer corresponding to the composition of the monomer component refers to the Fox based on the Tg of the homopolymer of each monomer contained in the monomer component and the weight fraction of the monomer. The value calculated from the formula. The formula of Fox is a relational expression between Tg of a copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below.
1 / Tg = Σ (Wi / Tgi)
In the above Fox equation, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of monomer i in the copolymer (copolymerization ratio on a weight basis), and Tgi is the monomer i. Represents the glass transition temperature (unit: K) of the homopolymer. However, in this specification, the calculation of Tg is performed considering only the monofunctional monomer. Therefore, when the monomer component includes a polyfunctional monomer, the total amount of the monofunctional monomer contained in the monomer component is defined as 100% by weight, and the Tg of the homopolymer of each monofunctional monomer and the above total amount of the monofunctional monomer Tg is calculated based on the weight fraction relative to.

As the Tg of the homopolymer, the following values are adopted for the monomers shown below.
2-Ethylhexyl acrylate -70 ° C
n-Butyl acrylate -55 ° C
Isostearyl acrylate -18 ℃
Cyclohexyl acrylate 15 ° C
Isobornyl acrylate 94 ° C
N-Vinyl-2-pyrrolidone 54 ° C
2-Hydroxyethyl acrylate -15 ° C
4-hydroxybutyl acrylate -40 ° C
Acrylic acid 106 ℃
For monomers other than those exemplified above, the values described in “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc., 1989) are used as the Tg of the homopolymer. The highest value is adopted for the monomer whose values are described in this document. When not described in the above Polymer Handbook, values obtained by the measurement method described in Japanese Patent Application Publication No. 2007-51271 are used.

(Composition for resin layer formation)
The composition for forming a resin layer disclosed herein includes a monomer component having the above-described composition in the form of a polymer, an unpolymerized product (that is, a form in which the polymerizable functional group is unreacted), or a mixture thereof. Can be included. The composition for forming a resin layer is a composition in which an organic solvent contains a resin layer forming component (for example, an adhesive component) (a composition for forming a solvent type resin layer), and a form in which the resin layer forming component is dispersed in an aqueous solvent. Composition (water-dispersed resin layer forming composition), a composition prepared to cure with active energy rays such as ultraviolet rays and radiation to form a resin layer forming component (active energy ray curable resin layer formation) And a hot melt type resin layer forming composition that forms a resin layer when coated in a heated and melted state and cooled to near room temperature.

The resin layer forming composition typically contains at least part of the monomer components of the composition (may be part of the type of monomer or part of the quantity). In the form of a polymer. The polymerization method for forming the polymer is not particularly limited, and various conventionally known polymerization methods can be appropriately employed. For example, thermal polymerization such as solution polymerization, emulsion polymerization and bulk polymerization (typically performed in the presence of a thermal polymerization initiator); photopolymerization performed by irradiation with light such as ultraviolet rays (typically It is carried out in the presence of a photopolymerization initiator.); Radiation polymerization carried out by irradiation with radiation such as β-rays and γ-rays; Of these, photopolymerization is preferred. In these polymerization methods, the mode of polymerization is not particularly limited, and conventionally known monomer supply methods, polymerization conditions (temperature, time, pressure, light irradiation amount, radiation irradiation amount, etc.), materials used other than monomers (polymerization initiator) , Surfactant, etc.) can be selected as appropriate.

In the polymerization, a known or commonly used photopolymerization initiator or thermal polymerization initiator can be used depending on the polymerization method, polymerization mode, and the like. Such a polymerization initiator can be used individually by 1 type or in combination of 2 or more types as appropriate.

The photopolymerization initiator is not particularly limited. For example, ketal photopolymerization initiator, acetophenone photopolymerization initiator, benzoin ether photopolymerization initiator, acylphosphine oxide photopolymerization initiator, α- Ketol photoinitiator, aromatic sulfonyl chloride photoinitiator, photoactive oxime photoinitiator, benzoin photoinitiator, benzyl photoinitiator, benzophenone photoinitiator, thioxanthone light A polymerization initiator or the like can be used.

Specific examples of the ketal photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one (for example, trade name “Irgacure 651” manufactured by BASF).
Specific examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl-phenyl-ketone (for example, trade name “Irgacure 184” manufactured by BASF), 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (for example, trade name “Irgacure 2959” manufactured by BASF), 2-hydroxy-2 -Methyl-1-phenyl-propan-1-one (for example, trade name “Darocur 1173” manufactured by BASF), methoxyacetophenone and the like are included.
Specific examples of the benzoin ether photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether and benzoin isobutyl ether, and substituted benzoin ethers such as anisole methyl ether.
Specific examples of the acylphosphine oxide photopolymerization initiator include bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (for example, trade name “Irgacure 819” manufactured by BASF), bis (2,4,6 -Trimethylbenzoyl) -2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (for example, trade name “Lucirin TPO” manufactured by BASF), bis (2,6- Dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and the like.
Specific examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one, and the like. It is. Specific examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride and the like. Specific examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime and the like. Specific examples of the benzoin photopolymerization initiator include benzoin and the like. Specific examples of the benzyl photopolymerization initiator include benzyl and the like.
Specific examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like.
Specific examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone. 2,4-diisopropylthioxanthone, dodecylthioxanthone and the like.

The thermal polymerization initiator is not particularly limited. For example, an azo polymerization initiator, a peroxide initiator, a redox initiator by a combination of a peroxide and a reducing agent, a substituted ethane initiator. Etc. can be used. More specifically, for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (2-amidinopropane) dihydrochloride 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (N, N′-dimethyleneisobutylamidine), 2,2 ′ -Azo initiators such as azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate; persulfates such as potassium persulfate and ammonium persulfate; benzoyl peroxide, t-butyl hydroperoxide Peroxide initiators such as hydrogen peroxide; substituted ethane initiators such as phenyl substituted ethane; persulfates and sulfites Combination of sodium hydrogen, redox initiators such as a combination of a peroxide and sodium ascorbate; but the like, without limitation. The thermal polymerization can be preferably carried out at a temperature of, for example, about 20 to 100 ° C. (typically 40 to 80 ° C.).

The amount of such a thermal polymerization initiator or photopolymerization initiator used can be a normal amount used according to the polymerization method, polymerization mode, etc., and is not particularly limited. For example, a polymerization initiator of 0.001 to 5 parts by weight (typically 0.01 to 2 parts by weight, for example, 0.01 to 1 part by weight) can be used with respect to 100 parts by weight of the monomer component to be polymerized. .

(Composition for forming a resin layer containing a polymerized monomer component and an unpolymerized product)
The resin layer forming composition according to a preferred embodiment includes a polymerization reaction product of a monomer mixture containing at least a part of the monomer component (raw material monomer) of the composition. Typically, a part of the monomer component is included in the form of a polymer, and the remainder is included in the form of an unpolymerized substance (unreacted monomer). The polymerization reaction product of the monomer mixture can be prepared by at least partially polymerizing the monomer mixture.
The polymerization reaction product is preferably a partial polymerization product of the monomer mixture. Such a partial polymer is a mixture of a polymer derived from the monomer mixture and an unreacted monomer, and typically exhibits a syrup shape (viscous liquid). Hereinafter, such a partially polymerized product may be referred to as “monomer syrup” or simply “syrup”.

The polymerization method for obtaining the polymerization reaction product is not particularly limited, and various polymerization methods as described above can be appropriately selected and used. From the viewpoints of efficiency and simplicity, a photopolymerization method can be preferably employed. According to photopolymerization, the polymerization conversion rate of the monomer mixture can be easily controlled by polymerization conditions such as the amount of light irradiation (light quantity).

The polymerization conversion rate (monomer conversion) of the monomer mixture in the partial polymer is not particularly limited. The polymerization conversion rate can be, for example, 70% by weight or less, and preferably 60% by weight or less. From the viewpoint of ease of preparation of the resin layer forming composition containing the partial polymer, coating properties, and the like, usually, the polymerization conversion rate is suitably 50% by weight or less, and 40% by weight or less (for example, 35% by weight). % Or less) is preferable. The lower limit of the polymerization conversion rate is not particularly limited, but is typically 1% by weight or more, and usually 5% by weight or more is appropriate.

The resin layer forming composition containing a partial polymer of the monomer mixture can be easily obtained by, for example, partially polymerizing a monomer mixture containing all of the raw material monomers by an appropriate polymerization method (for example, photopolymerization method). . The resin layer forming composition containing the partial polymer may contain other components used as necessary (for example, a photopolymerization initiator, a polyfunctional monomer, a crosslinking agent, an acrylic oligomer described later, and the like). . The method of blending such other components is not particularly limited, and for example, it may be previously contained in the monomer mixture or added to the partial polymer.

Further, in the resin layer forming composition disclosed herein, a complete polymerization product of a monomer mixture containing some types of monomers among the monomer components (raw material monomers) is converted into the remaining types of monomers or partial polymerization products thereof. It may be in a dissolved form. Such a resin layer forming composition is also included in examples of the resin layer forming composition containing a polymerized monomer component and an unpolymerized product. In the present specification, the “completely polymerized product” means that the polymerization conversion rate is more than 95% by weight.

As described above, a photopolymerization method can be preferably employed as a curing method (polymerization method) when forming a resin layer from a resin layer forming composition containing a polymerized monomer component and an unpolymerized product. In the resin layer forming composition containing the polymerization reaction product prepared by the photopolymerization method, it is particularly preferable to employ the photopolymerization method as the curing method. Since the polymerization reaction product obtained by the photopolymerization method already contains a photopolymerization initiator, when the resin layer forming composition containing this polymerization reaction product is further cured to form a resin layer, a new photopolymerization start is started. It can be photocured without adding an agent. Or the composition for resin layer formation of the composition which added the photoinitiator as needed to the polymerization reaction material prepared by the photopolymerization method may be sufficient. The photopolymerization initiator to be added may be the same as or different from the photopolymerization initiator used for the preparation of the polymerization reaction product. The resin layer forming composition prepared by a method other than photopolymerization can be made photocurable by adding a photopolymerization initiator. The photocurable resin layer forming composition has an advantage that even a thick resin layer can be easily formed. In a preferred embodiment, the photopolymerization when forming the resin layer from the resin layer forming composition can be performed by ultraviolet irradiation. A known high-pressure mercury lamp, low-pressure mercury lamp, metal halide lamp, or the like can be used for ultraviolet irradiation.

(Composition for forming a resin layer containing a monomer component in the form of a completely polymerized product)
The resin layer forming composition according to another preferred embodiment includes the monomer component of the composition in the form of a completely polymerized product. Such a resin layer forming composition is, for example, a solvent-type resin layer forming composition containing an acrylic polymer, which is a complete polymer of monomer components, in an organic solvent, water in which the acrylic polymer is dispersed in an aqueous solvent. It may be in the form of a dispersion type resin layer forming composition.

((Meth) acrylic oligomer)
The composition for forming a resin layer disclosed herein may contain a (meth) acrylic oligomer from the viewpoint of improving adhesive strength. By including a (meth) acrylic oligomer, the adhesive force of the resin layer can be improved.

The (meth) acrylic oligomer preferably has a Tg of about 0 ° C. or higher and 300 ° C. or lower, preferably about 20 ° C. or higher and 300 ° C. or lower, more preferably about 40 ° C. or higher and 300 ° C. or lower. When Tg is within the above range, the adhesive force can be preferably improved. Note that the Tg of the (meth) acrylic oligomer is a value calculated based on the Fox equation, similar to the Tg of the acrylic polymer.

The weight average molecular weight (Mw) of the (meth) acrylic oligomer may typically be 1000 or more and less than 30000, preferably 1500 or more and less than 20000, and more preferably 2000 or more and less than 10,000. It is preferable for Mw to be within the above range because good adhesive force and holding characteristics can be obtained. Mw of the (meth) acrylic oligomer is measured by GPC and can be obtained as a standard polystyrene equivalent value. Specifically, it is measured on a “HPLC 8020” manufactured by Tosoh Corporation using two TSKgelGMH-H (20) columns as a column and a tetrahydrofuran solvent at a flow rate of about 0.5 mL / min.

As a monomer constituting the (meth) acrylic oligomer, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl ( (Meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl Alkyl (meth) acrylates such as meth) acrylate, dodecyl (meth) acrylate; (meth) acrylic acid and alicyclic such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate Examples include esters with alcohols; aryl (meth) acrylates such as phenyl (meth) acrylate and benzyl (meth) acrylate; (meth) acrylates obtained from terpene compound derivative alcohols; and the like. Such (meth) acrylate can be used individually by 1 type or in combination of 2 or more types.

Examples of (meth) acrylic oligomers include alkyl (meth) acrylates in which alkyl groups such as isobutyl (meth) acrylate and t-butyl (meth) acrylate have a branched structure; cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, Esters of (meth) acrylic acid and alicyclic alcohols such as dicyclopentanyl (meth) acrylate; cyclic structures such as aryl (meth) acrylates such as phenyl (meth) acrylate and benzyl (meth) acrylate It is preferable that an acrylic monomer having a relatively bulky structure typified by (meth) acrylate is included as a monomer unit from the viewpoint of further improving adhesiveness. In addition, when ultraviolet rays are used in the synthesis of a (meth) acrylic oligomer or in the production of a resin layer, those having a saturated bond are preferred in that polymerization inhibition is unlikely to occur, and the alkyl group has a branched structure. An alkyl (meth) acrylate having an ester or an ester with an alicyclic alcohol can be preferably used as a monomer constituting the (meth) acrylic oligomer.

From this point, suitable (meth) acrylic oligomers include, for example, dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), In addition to dicyclopentanyl acrylate (DCPA), 1-adamantyl methacrylate (ADMA), and 1-adamantyl acrylate (ADA) homopolymers, a copolymer of CHMA and isobutyl methacrylate (IBMA), CHMA and IBXMA Copolymer, Copolymer of CHMA and acryloylmorpholine (ACMO), Copolymer of CHMA and diethylacrylamide (DEAA), Copolymer of ADA and methyl methacrylate (MMA), DCPMA and IB Copolymers of MA, copolymers of DCPMA and MMA, and the like.

When the resin layer forming composition disclosed herein contains a (meth) acrylic oligomer, the content thereof is not particularly limited, but is approximately 100 parts by weight of the monomer component contained in the resin layer forming composition. It is appropriate that the amount is 1 part by weight or more. From the viewpoint of better exhibiting the effect of the (meth) acrylic oligomer, the content of the (meth) acrylic oligomer is 3 parts by weight or more (for example, 5 parts by weight or more, typically 8 parts by weight or more). It is preferable to do. In addition, the content of the (meth) acrylic oligomer from the viewpoint of the curability of the resin layer forming composition and the compatibility with the partial polymer or the complete polymer of the acrylic polymer (and thus the transparency of the resin layer). Is suitably 70 parts by weight or less (for example 40 parts by weight or less, typically 20 parts by weight or less) with respect to 100 parts by weight of the monomer component contained in the resin layer forming composition. The technique disclosed here can also be implemented in an embodiment that does not use a (meth) acrylic oligomer.

(Silane coupling agent)
Further, the resin layer forming composition disclosed herein may contain a silane coupling agent. Examples of silane coupling agents that can be preferably used include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4-epoxy. (Cyclohexyl) ethyltrimethoxysilane and other epoxy group-containing silane coupling agents; 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- ( Amino group-containing silane coupling agents such as 1,3-dimethylbutylidene) propylamine, N-phenyl-γ-aminopropyltrimethoxysilane; 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, etc. (Meth) acrylic group Isocyanate group-containing silane coupling agents such as 3-isocyanate propyl triethoxysilane; Yes silane coupling agent, and the like. These can be used alone or in combination of two or more. The amount of the silane coupling agent is preferably 1 part by weight or less (for example, 0.01 to 1 part by weight), more preferably 0.02 to 100 parts by weight with respect to 100 parts by weight of the monomer component constituting the acrylic polymer. 0.6 parts by weight.

(Crosslinking agent)
The composition for resin layer formation disclosed here can contain a crosslinking agent. Examples of the crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, a silicone crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a silane crosslinking agent, an alkyl etherified melamine crosslinking agent, and a metal chelate crosslinking agent. Etc. These can be used alone or in combination of two or more. The addition amount of a crosslinking agent is appropriately set based on technical common sense. Or the composition for resin layer formation may not contain the above crosslinking agents.

(Other additives)
In addition, the resin layer forming composition disclosed herein may contain various additives known in the field of pressure-sensitive adhesives, for example. For example, powders such as colorants, pigments, dyes, surfactants, plasticizers, tackifying resins, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, A polymerization inhibitor, an inorganic or organic filler, metal powder, particles, foils, etc. can be appropriately added depending on the application.

(Formation method, etc.)
The resin layer disclosed herein can be formed, for example, as a resin layer by applying any of the resin layer forming compositions disclosed herein to a support and drying or curing. As a coating method of the resin layer forming composition, various conventionally known methods can be used. Specifically, for example, by roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

The resin layer forming composition can be dried under heating. The drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and further preferably 70 ° C to 170 ° C. By setting the heating temperature within the above range, a resin layer having excellent physical properties can be obtained. As the drying time, an appropriate time can be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and even more preferably 10 seconds to 5 minutes.

In forming the resin layer, in order to obtain desired physical properties, a crosslinking treatment, a thermosetting treatment, or the like can be further performed. For example, a thermosetting treatment can be performed at about 80 to 200 ° C. (eg, 100 to 180 ° C., typically 120 to 160 ° C.) for 5 minutes or more. The heat curing treatment time is preferably 10 minutes or longer, more preferably 20 minutes or longer (for example, 30 minutes or longer, typically 40 minutes to 120 minutes). The resin layer is preferably subjected to press treatment before or during the thermosetting treatment.

The resin layer disclosed herein can be obtained from the resin layer forming composition. The thickness of the resin layer is not particularly limited, and can be, for example, about 1 to 400 μm. Usually, the thickness of the resin layer is preferably 1 to 200 μm, more preferably 2 to 150 μm, further preferably 2 to 100 μm, and particularly preferably 5 to 75 μm.

In a mode in which the conductive portion is laminated on the resin layer in advance, the resin layer before the conductive portion is placed is spirally overlapped with a release liner (support) whose front surface and back surface are both release surfaces (peelable surfaces). It may be in a form wound in a shape. Alternatively, the first surface and the second surface may be respectively protected by two independent release liners (supports). As the release liner, those described below can be preferably used.

<Release liner>
As the release liner for protecting the first resin layer, the second resin layer, and the upper and lower surfaces of the wiring structure, a conventional release paper or the like can be used, and is not particularly limited. For example, a release liner having a release treatment layer on the surface of a substrate such as a plastic film or paper, or a release made of a low adhesive material such as a fluorine polymer (polytetrafluoroethylene, etc.) or a polyolefin resin (polyethylene, polypropylene, etc.) A liner or the like can be used. The release treatment layer may be formed by surface-treating the base material with a release treatment agent. Examples of the release treatment agent include a silicone release treatment agent, a long-chain alkyl release treatment agent, a fluorine release treatment agent, and molybdenum (IV) sulfide.

<Solar cell>
The type of the solar battery cell to be used is not particularly limited, and for example, a single crystal type or a polycrystalline type Si cell is suitable. The crystalline Si cell may be a p-type cell (a cell in which n-type is added to a p-type substrate) or an n-type cell (a cell in which p-type is added to an n-type substrate). Further, the solar battery cell may be an amorphous Si cell, a compound solar battery, an organic solar battery cell or the like. Further, the solar cell may be either a single-sided light receiving type or a double-sided light receiving type. The shape of the solar battery cell is not particularly limited, and it may be a wafer having a substantially rectangular plane, or may be a belt shape. The thickness of the solar battery cell is preferably about 0.5 mm or less, more preferably about 0.3 mm or less (for example, about 180 to 200 μm), and further preferably about 160 μm or less from the viewpoint of lightness and the like.

<Sealing resin>
The sealing resin disclosed herein may have insulating properties and translucency. For example, it may be a resin layer that can exhibit fluidity by heat or pressure. In this specification, “having insulation” means a specific resistance at 25 ° C. of 1 × 10 ⁶ Ω · cm or more (preferably 1 × 10 ⁸ Ω · cm or more, typically 1 × 10 ¹⁰ Ω). -Cm or more). In this specification, the electric resistance (for example, specific resistance) is a value at 25 ° C. unless otherwise specified. Further, in the present specification, “having translucency” means that the total light transmittance defined by JIS K 7375: 2008 is 50% or more (preferably 80% or more, typically 95% or more). That means.

The sealing resin may preferably be a thermosetting resin. The sealing resin made of a thermosetting resin can be well sealed in the solar battery module by, for example, laminating and heating the solar battery cell. As the resin, an ethylene-vinyl acetate copolymer (EVA) is preferably used from the viewpoints of translucency, workability, weather resistance, and the like. The above resins include ethylene-vinyl ester copolymers represented by EVA, ethylene-unsaturated carboxylic acid copolymers such as ethylene- (meth) acrylic acid copolymers, ethylene- (meth) acrylic acid esters, etc. An ethylene-unsaturated carboxylic acid ester copolymer, an unsaturated carboxylic acid ester-based polymer such as polymethyl methacrylate, and the like may be used. Alternatively, fluoropolymers such as vinylidene fluoride resin and polyethylene tetrafluoroethylene; manufactured using low density polyethylene (LDPE), linear low density polyethylene (LLDPE, typically Ziegler catalyst, vanadium catalyst, metallocene catalyst, etc. Can be produced using polyethylene (PE) such as LLDPE), polypropylene (PP. For example, PP that can be produced using Ziegler catalyst, Phillips catalyst, metallocene catalyst, etc.), Ziegler catalyst, vanadium catalyst, metallocene catalyst, etc. Polyolefins such as ethylene / α-olefin copolymers and their modified products (modified polyolefins); Polybutadienes; Polyvinyl acetals such as polyvinyl formal, polyvinyl butyral (PVB resin), and modified PVB; polyethylene Terephthalate (PET); polyimide; amorphous polycarbonate; siloxane sol - gel; polyurethane; polystyrene; polyether sulfone; polyarylate, epoxy resins, may be like; silicone resin; ionomers. These resins may be used alone or in combination of two or more. The resin may contain various additives known in the art such as an ultraviolet absorber and a light stabilizer.

In addition, an adhesion improver may be added to the sealing resin in order to improve the adhesion with the conductive part and the wiring structure. For example, after an adhesion improver is applied to the surface of the sheet-shaped sealing resin before heat curing, the wiring structure is disposed on the surface, and the sealing resin and the wiring structure are heat-treated. Adhesion with is improved. When an EVA sheet is used as the sealing resin, a silane coupling agent is preferably used as the adhesion improver. Various surface treatments such as corona treatment and atmospheric pressure plasma treatment can be applied to the surface of the sheet-shaped sealing resin alone or in combination for the purpose of improving adhesion and the like.

The thickness of the sheet-shaped sealing resin used for the construction of the solar cell module is about 100 to 2000 μm (for example, 200 to 1000 μm, typically 400 to 800 μm) from the viewpoint of the sealing performance of the solar battery cell. It is preferable.

<Surface covering member>
As the surface covering member, various materials having translucency can be used. Surface covering member is glass plate, fluororesin sheet such as tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride resin, chlorotrifluoroethylene resin, acrylic resin, polyethylene terephthalate It may be a resin sheet composed of a material such as polyester such as (PET) or polyethylene naphthalate (PEN). For example, a flat plate member or a sheet member having a total light transmittance of 70% or more (for example, 90% or more, typically 95% or more) can be preferably used. The total light transmittance may be measured according to JIS K 7375: 2008. The thickness of the surface covering member is preferably about 0.5 to 10 mm (for example, 1 to 8 mm, typically 2 to 5 mm) from the viewpoint of protection and light weight.

<Backside coating member>
As the back surface covering member, a flat plate member or a sheet member made of various materials exemplified as the material of the surface covering member is preferably used. Especially, it is more preferable to use polyester, such as PET and PEN, as a back surface covering member forming material. Or as a back surface covering member, you may use the metal sheet (for example, aluminum plate) which has corrosion resistance, resin sheets, such as an epoxy resin, and composite sheets, such as silica vapor deposition resin. The thickness of the back surface covering member is preferably about 0.1 to 10 mm (for example, 0.2 to 5 mm) from the viewpoints of handleability and lightness. In addition, the back surface covering member may not have translucency.

Hereinafter, examples relating to the present invention will be described, but the present invention is not intended to be limited to those shown in the specific examples. In the following description, “parts” and “%” are based on weight unless otherwise specified.

≪Experiment 1≫
<Materials used>
(First resin layer and second resin layer)
40.5 parts of 2-ethylhexyl acrylate, 40.5 parts of isostearyl acrylate, 18 parts of N-vinyl-2-pyrrolidone, 1 part of 4-hydroxybutyl acrylate, and 2,2-dimethoxy-1, as a photopolymerization initiator 0.05 part of 2-diphenylethane-1-one (trade name “Irgacure 651”, manufactured by BASF) and 0.05 part of 1-hydroxycyclohexyl-phenyl-ketone (trade name “Irgacure 184”, manufactured by BASF) Were mixed and irradiated with ultraviolet rays in a nitrogen atmosphere to prepare a partially polymerized product (monomer syrup). To the obtained monomer syrup, 0.3 part of a silane coupling agent (trade name “KBM403”, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.02 part of trimethylolpropane triacrylate (TMPTA) are added and mixed uniformly. A layer forming composition was prepared.
The composition for forming a resin layer prepared above is applied to the release treatment surface of a 38 μm thick polyester film (trade name “Diafoil MRF”, manufactured by Mitsubishi Plastics, Inc.) whose one surface is release-treated with a silicone release treatment agent. The coating layer was formed by coating so that the final thickness was 46 μm. Next, a 38 μm thick polyester film (trade name “Diafoil MRE”, manufactured by Mitsubishi Plastics Co., Ltd.) having one side peeled with silicone is applied to the surface of the coating layer. I put it on the side. Thereby, the coating layer was shielded from oxygen. By irradiating the sheet having the coating layer thus obtained with ultraviolet rays having an illuminance of 5 mW / cm ² for 360 seconds using a chemical light lamp (manufactured by Toshiba Corporation), the coating layer is cured and a resin layer (adhesive) Agent layer) was formed to obtain resin sheets (adhesive sheets) as the first resin layer and the second resin layer. In this resin sheet, the polyester film coated on both surfaces of the resin sheet functions as a release liner.
The illuminance value is a value measured by an industrial UV checker (trade name “UVR-T1”, light receiving unit type UD-T36, manufactured by Topcon Corporation) having a peak sensitivity wavelength of about 350 nm.

(Conductive part)
A plurality of plated copper wires (width 0.8 mm, thickness 0.25 mm, rectangular cross section) shown in Table 1 were prepared. The plated copper wire used had a width tolerance of ± 10%, a thickness tolerance of ± 4%, a plating thickness of 1.5 μm or more, and a tensile strength of 200 N / mm ² or more. As the plating type, silver having the purity shown in Table 1 was used. The roughness of the conductive part surface and the diffuse reflectance are adjusted by the etching process of the copper wire, the purity of the silver plating, and the plating thickness (film thickness).

(Sealing resin)
EVA sheet (trade name “EVASKY”, manufactured by Bridgestone, thickness 450 μm)
(Solar cell)
Si solar cell (polycrystalline Si cell, manufactured by GINTECH)
(Surface covering member)
Glass plate (white plate heat-treated glass, manufactured by Shinyi Glass Co., Ltd., thickness 3.2 mm)
(Back cover member)
Back sheet (trade name “KOBATEC PV KB-Z1-3”, manufactured by Kobayashi Corporation, thickness 200 μm)

<Samples 1 to 9>
Using the above materials, a test solar cell module having the same configuration as in the above embodiment was constructed. In this solar cell module for test, two solar cells were used. The resin sheets as the first resin layer and the second resin layer were each cut into an appropriate size according to the shape of the solar battery cell, and placed in two solar battery cells. As the conductive part, eight plated copper wires shown in Table 1 were used, and the copper wires were arranged at 2 cm intervals so that the longitudinal direction of the copper wires was parallel to the arrangement direction of the solar cells. The sealing resin was also cut into an appropriate size according to the shape of the module. The solar cell module for testing was placed on the above materials, then laminated using a commercially available laminator (manufactured by NPC) at 150 ° C. and 100 kPa for 5 minutes, cured for 15 minutes, and further commercially available. This was constructed by performing a drying treatment at 150 ° C. for 15 minutes using a blast constant temperature thermostat (manufactured by Yamato Kagaku Co., Ltd.).

<Reference sample>
Without using the conductive part and the first and second resin layers, three bus bar electrodes (trade name “SSA-SPS”, 1.5 mm × 0.2 mm solder-coated copper wire, manufactured by Hitachi Cable Ltd.) are soldered together A solar cell module was constructed in the same manner as the above sample except that the Si-based solar cells (polycrystalline cell manufactured by GINTECH) were used.

With respect to the solar cell module obtained above, a short circuit current Jsc (mA / cm ² ) was measured using a solar simulator (device name “XES-450S1”, manufactured by Mitsunaga Electric Mfg. Co., Ltd.). The results are shown in Table 1 and FIG. The table also shows the diffuse reflectance (%), silver plating purity (%), and Ra (μm) on the surface of the conductive part. In the table, “-” represents unmeasured.

As shown in Table 1 and FIG. 9, the diffuse reflectance on the surface of the conductive part and the short-circuit current Jsc showed a positive proportional relationship. In particular, Samples 1 to 6 in which the diffuse reflectance on the surface of the conductive portion was 60% or higher showed a relatively high short-circuit current Jsc. From this result, it can be seen that the power generation efficiency is improved according to the solar cell module using the conductive portion having a diffuse reflectance of 60% or more on the solar cell module light incident surface side.

≪Experiment 2≫
A plurality of plated copper wires (width 0.8 mm, thickness 0.25 mm, rectangular cross section) having different plating thicknesses were prepared as the conductive portions. As the plated copper wire, one having a width tolerance of ± 10%, a thickness tolerance of ± 4%, a tensile strength of 200 N / mm ² or more, and a plating type of silver having a purity of 99.9 wt% or more was used. About the said electroconductive part, the diffuse reflectance (%) of the surface was measured. FIG. 10 shows the relationship between the plating thickness (μm) and the diffuse reflectance (%).

As shown in FIG. 10, the diffuse reflectance improved as the plating thickness of the conductive part increased. In particular, it was shown that when the plating thickness is 1.5 μm or more, a diffuse reflectance of 90% or more is realized. In Experiment 1 above, the diffuse reflectance on the surface of the conductive part and the short-circuit current Jsc show a positive proportional relationship, and thus it can be seen that the power generation efficiency can be improved by increasing the plating thickness of the conductive part.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

DESCRIPTION OF SYMBOLS 1 Wiring structure 2 Wiring structure with peeling liner 10 1st area | region 12 2nd area | region 30, 30a, 30b, 30c, 30d, 30z Conductive part 30A Solar cell module light-incidence surface side surface 40, 40a, 40b of an electrically conductive part, 40z Metal wire 40A Solar cell module light incident surface side surface of metal wire 42 Core material 44 Cover 50, 50a, 50b, 50c, 50d First resin layer 60, 60a, 60b, 60c, 60d Second resin layer 70 First Release liner 72 Second release liner 74 Third release liner 76 Fourth release liner 100 Solar cell module 110 Solar cell group 110a, 110b, 110c, 110d Solar cell 120 Wired solar cell group 150 Sealing resin 160 Surface coating Member 170 Back surface covering member

Claims (10)

A solar cell module comprising a plurality of solar cells arranged at intervals and a conductive portion that electrically connects two adjacent solar cells among the plurality of solar cells,
The solar cell module in which at least the solar cell module light incident surface side surface of the conductive portion exhibits a diffuse reflectance of 60% or more. The solar cell module according to claim 1, wherein at least a solar cell module light incident surface side surface of the conductive portion exhibits a diffuse reflectance of 80% or more. The solar cell module according to claim 1 or 2, wherein at least a solar cell module light incident surface side surface of the conductive portion is made of silver having a purity of 99.7% by weight or more. The solar cell module according to any one of claims 1 to 3, wherein an arithmetic average roughness (Ra) of at least a solar cell module light incident surface side surface of the conductive portion is 60 nm or more. The solar cell module according to any one of claims 1 to 4, wherein the conductive portion is made of a plurality of metal wires arranged at intervals. The solar cell module according to claim 5, wherein the metal wire is plated with a thickness of 1.5 μm or more. A conductive material for electrically connecting two adjacent solar cells among a plurality of solar cells arranged in a solar cell module,
The said electrically conductive material is a electrically conductive material for solar cell modules which has the surface which shows the diffuse reflectance of 60% or more. A wiring structure for electrically connecting two adjacent solar cells among a plurality of solar cells arranged in a solar cell module,
A transparent resin layer, and a conductive portion partially disposed on the first surface of the transparent resin layer,
A wiring structure in which at least the transparent resin layer side surface of the conductive portion exhibits a diffuse reflectance of 60% or more. The wiring structure according to claim 8, wherein the transparent resin layer is an adhesive layer. The wiring structure according to claim 8 or 9, wherein the transparent resin layer is a crosslinked pressure-sensitive adhesive layer.

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