JP2016157760A - Colored encapsulation material sheet for solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, with high productivity, a colored encapsulation material sheet for a solar battery module that has both of a molding characteristic and heat resistance performance, and can suppress wraparound of a colored portion in an integration process as a solar battery module.SOLUTION: A colored encapsulation material sheet 1 is configured as a multilayer sheet in which a transparent outermost layer 12 is laminated on a colored intermediate layer 11. The colored intermediate layer 11 has base resin formed of polyethylene-based resin whose density ranges from not less than 0.870 g/cmto not more than 0.970 g/cm. The transparent outermost layer 12 has base resin formed of polyethylene-based resin whose density ranges from not less than 0.870 g/cmto not more than 0.900 g/cm. When the dynamic viscoelasticity (Tanδ) of the transparent outermost layer 12 at the temperature of the melting point of the transparent outermost layer 12 + 20°C is represented by A and the dynamic viscoelasticity (Tanδ) of the colored intermediate layer 11 at the temperature of the melting point of the colored intermediate layer 11 + 20°C is represented by B, the ratio (A/B) of A and B ranges from not less than 10to not more than 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a colored sealing material sheet for a solar cell module. More specifically, the present invention relates to a colored encapsulant sheet such as a white encapsulant sheet, and relates to a colored encapsulant sheet disposed exclusively on the non-light-receiving surface side of a solar cell element in a solar cell module.

  In recent years, solar cells as a clean energy source have attracted attention due to the growing awareness of environmental issues. Currently, various types of solar cell modules have been developed and proposed. In general, as shown in FIG. 2, the solar cell module has a configuration in which a transparent front substrate 4 made of glass or the like, a solar cell element 3, and a back surface protection sheet 5 are laminated via sealing material sheets 1 and 2. .

  In such a solar cell module, in order to obtain a high electrical output, a plurality of solar cell elements 3 are connected and used, and the plurality of solar cell elements 3 have impact resistance, heat resistance, and weather resistance. And the sealing material sheets 1 and 2 having insulating properties.

  As such a sealing material sheet for a solar cell module, one using EVA (ethylene-vinyl acetate copolymer) as a base resin has been widely used. However, in recent years, as a solution to the problem of deterioration of water vapor barrier properties in long-term use, which is a drawback of EVA resin, sealing for solar cell modules using low-density polyethylene resin instead of EVA resin Material sheets have been proposed.

  Here, in the solar cell module, as the encapsulant sheet disposed on the non-light-receiving surface side of the solar cell element, a colored encapsulant sheet (hereinafter referred to as “white”) is blended with a colorant such as titanium oxide. , Also referred to as “colored sealing material sheet”) (see Patent Document 1). By arranging these colored encapsulant sheets on the non-light-receiving surface side of the solar cell element, a transparent encapsulant sheet (hereinafter also referred to as “transparent encapsulant sheet”) disposed on the light-receiving surface side Due to the reflection of light at the interface and the irregular reflection of light by the colorant, the utilization efficiency of the light incident on the solar cell module can be increased, and the power generation efficiency of the solar cell can be improved.

  However, a solar cell module is generally manufactured by bonding and integrating a solar electronic element and a module constituent member including the above-described sealing material sheet or the like by a lamination method or the like with a heating and pressing process. When the colored sealing material sheet is used for the purpose of improving power generation efficiency or design, the colored sealing is laminated on the non-light-receiving surface side of the solar electronic element during the heating and pressurizing treatment. The material sheet flows, wraps around the surface side of the solar cell element (light-receiving surface side) from the side surface of the laminate and the gap between the solar cell elements, and part of the front side (incident light side) of the solar cell element There is a problem that the covering area reduces the power generation area of the solar cell element, and as a result, the power generation efficiency of the solar cell module decreases.

  As a means for preventing such a phenomenon of unnecessary wraparound of the colored sealing material (hereinafter also simply referred to as “wraparound”), for example, a colored sealing material sheet disposed on the non-light-receiving surface side of the solar cell element is used. A solar cell module that attempts to solve the above problem by adjusting the MFR of the transparent sealing material sheet disposed on the light receiving surface side to be higher than the MFR has been proposed (see Patent Document 2).

  On the other hand, in Patent Document 3, as a means for preventing the above-described wraparound, a sealing material sheet, which is a laminate composed of a transparent layer made of ethylene resin such as EVA and a colored layer, is a solar cell element. It has been proposed as a colored sealing material sheet disposed on the non-light-receiving surface side.

JP 2006-210405 A Japanese Patent Laying-Open No. 2005-050928 JP 2011-216804 A

  However, in the solar cell module described in Patent Document 2, the above phenomenon may not be prevented depending on the EVA melt flow rate, vinyl acetate content, and heating and pressing conditions in the solar cell manufacturing process. In addition, there is a problem that setting of manufacturing conditions is extremely complicated and difficult. In addition, since the sealing material sheets used on the light receiving surface side and the non-light receiving surface side are limited as combinations, the degree of freedom of material selection is reduced, which also causes a decrease in productivity and an increase in cost. .

  According to the colored sealing material sheet described in Patent Document 3, it can be expected to avoid the wraparound to some extent while being released from the restriction of the combination of the sealing material sheets in the module configuration described above. However, although the colored sealing material sheet described in Patent Document 3 is based on the premise that a resin having a polar group such as EVA is used, as described above, the EVA has a reduced water vapor barrier property in a long-term use. There was a problem.

  On the other hand, when the base resin is a polyethylene resin that is superior in hydrolysis resistance compared to EVA, the polyethylene resin tends to have insufficient molding characteristics when modularized, and on the contrary, the molding characteristics are sufficiently secured. For this reason, if the materials and production conditions are adjusted in the direction of increasing the fluidity of the resin, there is a problem that sufficient heat resistance cannot be obtained.

  The present invention has been made in view of the above situation, and is released from the limitation of the combination with the sealing material sheet disposed on the light receiving surface side, the strict temperature adjustment conditions in the manufacturing process, and the like. In addition to having the molding properties and heat resistance required for solar cell module sealing material sheets at a high level, it is possible to sufficiently suppress the wraparound of colored parts when integrated as a solar cell module. It is an object of the present invention to provide a colored sealing material sheet for a solar cell module with high productivity using a polyethylene resin having excellent hydrolysis resistance as a base resin.

  As a result of intensive studies, the inventors have made a colored encapsulant sheet for solar cell modules, a colored intermediate layer and a transparent outermost layer using a low-density polyethylene resin in a predetermined density range for each layer. And by adjusting the value of dynamic viscoelasticity (Tanδ) of each layer of the multi-layered sheet to a specific range peculiar to the present application, The present invention has been completed. More specifically, the present invention provides the following.

(1) A colored encapsulant sheet for a solar cell module, wherein the colored encapsulant sheet is a multilayer in which a transparent outermost layer not containing a coloring material is laminated on a colored intermediate layer containing a coloring material. a sheet, the colored intermediate layer, the density of 0.870 g / cm ³ or more 0.970 g / cm ³ or less of the polyethylene resin as a base resin, the transparent outermost layer, density 0.870 g / cm ³ or more 0 The base resin is a polyethylene resin of 900 g / cm ³ or less, the dynamic viscoelasticity (Tanδ) of the transparent outermost layer at a temperature of the melting point of the transparent outermost layer + 20 ° C. is A, and the colored intermediate layer When the value of dynamic viscoelasticity (Tanδ) of the colored intermediate layer at the melting point of the colored intermediate layer + 20 ° C. is B, the ratio of A to B (A / B) is 10 ² or more and 10 ^6. Colors that are Sealing material sheet.

(2) The colored intermediate layer has a dynamic viscoelasticity (Tanδ) at a temperature of the melting point of the colored intermediate layer + 20 ° C. of from 0.1 to 1.0, and the transparent outermost layer is the transparent outermost layer. The colored sealing material sheet according to (1), wherein the dynamic viscoelasticity (Tan δ) at the melting point of the outer layer + 20 ° C. is 10 ² or more and 10 ⁵ or less.

(3) The colored outer seal according to (1) or (2), wherein the transparent outermost layer has a dynamic viscoelasticity (Tanδ) at a temperature of the melting point of the transparent outermost layer + 20 ° C. of 10 ² or more and 10 ³ or less. Stop sheet.

  (4) The colored sealing material sheet according to any one of (1) to (3), wherein the coloring material is a white coloring agent selected from the group consisting of calcium carbonate, barium sulfate, zinc oxide, and titanium oxide.

  (5) The colored sealing material sheet according to any one of (1) to (4), wherein the transparent outermost layer includes an adhesive copolymer resin made of a silane-modified polyethylene resin.

  (6) A solar cell module comprising the colored encapsulant sheet according to any one of (1) to (5) and a solar cell element, wherein the colored encapsulant sheet is the solar cell element. A solar cell module disposed only on the non-light-receiving surface side.

  (7) The colored sealing material manufacturing method according to any one of (1) to (5), wherein the multilayer sheet is subjected to a crosslinking treatment by irradiation with ionizing radiation. Sheet manufacturing method.

  According to the present invention, a colored seal for a solar cell module that combines molding characteristics and heat resistance at a high level and can sufficiently suppress the wraparound of the colored portion when integrated as a solar cell module. A stopping material sheet can be provided under high productivity by using a polyethylene resin having excellent hydrolysis resistance as a base resin.

It is a cross-sectional schematic diagram which shows an example of the layer structure of the colored sealing material sheet | seat of this invention. It is a cross-sectional schematic diagram which shows an example of the laminated constitution of the solar cell module using the colored sealing material sheet | seat of this invention.

  Hereinafter, the sealing material composition used for the production of the colored sealing material sheet of the present invention, the colored sealing material sheet of the present invention and the production method thereof, and the solar cell module using the colored sealing material sheet of the present invention. A description will be made sequentially.

<Encapsulant composition>
The colored sealing material sheet of the present invention includes a colored intermediate layer containing a coloring material that expresses a desired color in its appearance, and a transparent outermost layer that is laminated on the colored intermediate layer and does not contain a coloring material. A multilayer encapsulant sheet. And the colored sealing material sheet of the present invention comprises a colored intermediate layer sealing material composition containing a coloring material for forming a colored intermediate layer, and a coloring material for forming a transparent outermost layer. Each layer is formed from a sealing material composition for the transparent outermost layer not contained, and the dynamic viscoelasticity (Tanδ) value of each layer is adjusted to a specific range unique to the present application. It has been done. Each encapsulant composition for each of the above layers uses a low density polyethylene resin as a base resin. However, as the base resin, a low density polyethylene resin having a density limited to a specific range is appropriately selected for each layer. Further, the multi-layer sheet obtained by laminating the single-layer sheets made of the sealing material compositions for the respective layers thus selected is subjected to a crosslinking treatment by irradiation with ionizing radiation, whereby the colored seal of the present invention. A stopping material sheet can be obtained.

  Here, the “value of dynamic viscoelasticity (Tanδ)” in the present specification means a storage elastic modulus (measurement of dynamic viscoelasticity (Tanδ)) obtained by the method described in the following examples. E ′) and the loss elastic modulus (E “), which can be obtained by the following calculation formula. From the transition of this value for each temperature, the storage elastic modulus (E ′) and the loss elastic modulus (E“ ) Temperature dependence. Specifically, the loss tangent: Tanδ = E ″ / E ′ can be calculated from the quotient with the storage elastic modulus (E ′) as the denominator and the loss elastic modulus (E ″) as the numerator.

  In the present specification, when the melting point of each layer such as a colored intermediate layer is referred to, unless otherwise specified, the encapsulant composition constituting each layer of the encapsulant sheet is in a completed stage as an encapsulant sheet. We shall refer to the melting point. The melting point refers to the temperature of the melting point measured by a conventionally known DSC method.

[Encapsulant composition for colored intermediate layer]
The encapsulant composition for the colored intermediate layer is an encapsulant composition used for forming the colored intermediate layer in the multilayer colored encapsulant sheet of the present invention. The encapsulant composition for the colored intermediate layer uses a low density polyethylene resin in a predetermined density range as a base resin, and contains a coloring material such as titanium oxide.

Then, the encapsulant composition for the colored intermediate layer is obtained by the dynamic viscoelasticity (Tanδ) of the transparent outermost layer at the melting point of the transparent outermost layer, which will be described in detail below, at a temperature of 20 ° C. ) Is A, and the ratio (A / B) of A to B is B where the value of the dynamic viscoelasticity (Tanδ) of the colored intermediate layer at the melting point of the colored intermediate layer + 20 ° C. is B. , to be in the range of 10 ² to 10 ⁶ or less, advance what material resin is selected appropriately. The dynamic viscoelasticity (Tan δ) of the colored intermediate layer at the melting point + 20 ° C. is preferably 0.1 or more and 1.0 or less. Thus, by adjusting the dynamic viscoelasticity (Tanδ) of the colored intermediate layer, the colored sealing material sheet of the present invention has sufficient heat resistance, and also has excellent physical properties for molding characteristics. It becomes a colored sealing material sheet.

(Base resin)
As the base resin for the colored intermediate layer, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), or metallocene linear low density polyethylene (M-LLDPE) can be preferably used.

The density of polyethylene resin can be used as a colored intermediate layer base resin, 0.870 g / cm ³ or more 0.970 g / cm ³ or less, preferably, 0.870 g / cm ³ or more 0.930 g / cm ³ or less It is. And it is preferable that the density of base resin for colored intermediate | middle layers is a relatively high density rather than the base resin of the sealing material composition for transparent outermost layers which demonstrates a detail later. By setting the density of the base resin for the colored intermediate layer within the above range, it is possible to obtain a colored sealing material sheet having sufficient heat resistance while maintaining the molding characteristics of the colored sealing material sheet.

  As the base resin for the colored intermediate layer, the dynamic viscoelasticity (Tanδ) of the colored intermediate layer at a temperature of the melting point of the colored intermediate layer + 20 ° C. is 0.1 or more and 1.0 or less after the crosslinking treatment by irradiation with ionizing radiation. A resin that can be used is used.

  On the other hand, the colored intermediate layer base resin is preferably a polyethylene resin in which the number of full double bonds remaining in the composition stage is relatively larger than the number of full double bonds of the transparent outermost layer base resin. . Further, the number of full double bonds of the base resin for the colored intermediate layer is preferably 0.5 or more and 4.0 or less, and more preferably 1.0 or more and 4.0 or less.

  By limiting the number of full double bonds of the base resin for the colored intermediate layer to the above range in combination with the base resin for the transparent outermost layer, cross-linking by irradiation with ionizing radiation is appropriately promoted and the colored encapsulant sheet Heat resistance can be maintained within a preferred range. On the other hand, even if the crosslinking of the colored intermediate layer is sufficiently promoted as described above, the total double bond number of the sealing material composition for the transparent outermost layer is different from that of the sealing material composition for the colored intermediate layer. By limiting to a small range of the number of double bonds, the progress of crosslinking of the transparent outermost layer can be suppressed in a mode different from that of the colored intermediate layer. As a result, preferable molding characteristics can be maintained as the whole colored encapsulant sheet. In addition, the heat resistance of a colored sealing material sheet | seat is not fully improved as the number of full double bonds of the sealing material composition for colored intermediate | middle layers is less than 0.5 piece. On the other hand, if the number exceeds 4.0, the molding properties of the colored encapsulant sheet deteriorate due to excessive crosslinking, which is not preferable.

Here, “the number of full double bonds” in the present specification means the sheet density d (g / cm ³ ) and sheet thickness t (cm) of the encapsulant composition in the sheet state and the absorption band of the infrared absorption spectrum. It is the value calculated | required by the following formula from the light absorbency A. In addition, about the measurement of the light absorbency A of the absorption band of an infrared absorption spectrum, it carried out by NICOLET6700 made from Thermo Scientific.
Number of terminal vinyl groups = 0.231 / (d × t) × A (910 cm ⁻¹ )
Vinylidene base = 0.271 / (d × t) × A (888 cm ⁻¹ )
Number of trans vinylene groups = 0.328 / (d × t) × A (965 cm ⁻¹ )
Total number of double bonds = number of terminal vinyl groups + number of vinylidene groups + number of transvinylene groups The total number of double bonds per 2000 carbons by the above method.

  The content of the base resin for the colored intermediate layer contained in the sealing material composition for the colored intermediate layer is preferably based on 100 parts by mass of the total resin components in the sealing material composition for the colored intermediate layer. It is 10 to 99 parts by mass, more preferably 50 to 99 parts by mass, and still more preferably 90 to 99 parts by mass. Other resins may be included as long as the number of residual double bonds at the composition stage falls within the above range. These may be used, for example, as an additive resin, or may be used for masterbatching other components described later. In the present specification, the term “all resin components” includes the other resins described above.

(Coloring material)
The sealing material composition for the colored intermediate layer contains a coloring material for expressing a preferable appearance and light reflection performance as the colored sealing material sheet. As such a coloring material, a white colorant made of an inorganic compound can be preferably used. By including such a white colorant, when the colored encapsulant sheet of the present invention is arranged as an encapsulant layer on the non-light-receiving surface side in the solar cell module, the incident light into the solar cell module The power generation efficiency of the solar cell module can be improved.

  Although it does not specifically limit as said white colorant, For example, white pigments, such as a calcium carbonate, barium sulfate, a zinc oxide, and a titanium oxide, can be used preferably. Among these, titanium oxide can be particularly preferably used from the viewpoint of versatility.

  The white pigment preferably has a particle size of 0.5 μm to 1.5 μm. If the particle size of the white pigment is in the above range, the white layer formed from it effectively reflects near infrared rays in addition to the visible light region, so that the particles that can further contribute to the power generation efficiency improvement of the solar cell module. A typical example of a white pigment having a diameter of 0.5 μm or more and 1.5 μm or less is titanium oxide, and it is preferable to use titanium oxide as the white pigment in order to improve the reflection performance of sunlight.

  In addition, about the point of such power generation efficiency improvement, although it is desirable to whiten the sealing material layer by the side of the non-light-receiving surface in a solar cell module as mentioned above, light reflectivity other than white is obtained. If it is such a color tone, for example, it may be colored yellow, green, light blue or the like. In addition, even in the case where it is required to color the sealing material sheet in black or other colors in order to improve the designability, the content having a desired color is appropriately set within the condition range of the constituent requirements of the present invention. It can be used as a colored sealing material sheet having a desired color.

  In addition, the colored sealing material sheet of the present invention is configured such that the coloring material is contained only in the colored intermediate layer 11, so that the adhesion of the transparent outermost layer 12 disposed on the outer layer side is that of the coloring material. It is also prevented from deteriorating due to the influence.

[Encapsulant composition for transparent outermost layer]
The encapsulant composition for the transparent outermost layer is used for molding the outermost transparent layer formed on at least one outer surface, preferably both outermost surfaces of the multilayer colored encapsulant sheet of the present invention. It is a material composition. The sealing material composition for the transparent outermost layer uses a polyethylene-based resin in a predetermined low density range relatively lower than that used for the sealing material composition for the colored intermediate layer as a base resin, It is more preferable to contain an adhesive copolymer resin made of a silane-modified polyethylene resin or the like.

In the sealing material composition for the transparent outermost layer, the value of the dynamic viscoelasticity (Tanδ) of the transparent outermost layer at a temperature of the melting point of the transparent outermost layer + 20 ° C. is A in the completion stage of the sealing material sheet. When the value of the dynamic viscoelasticity (Tanδ) of the colored intermediate layer at the temperature of the melting point of the colored intermediate layer + 20 ° C. is B, the ratio of A to B (A / B) is 10 ² or more and 10 ⁶ The material resin is appropriately selected in advance so as to be in the following range. Also, the dynamic viscoelasticity of the transparent outermost layer in the temperature of the transparent outermost melting point + 20 ℃ (Tanδ) is preferably 10 ² or more. Thus, by adjusting the dynamic viscoelasticity (Tan δ) of the transparent outermost layer, the colored encapsulant sheet of the present invention has sufficient heat resistance due to sufficient crosslinking. In addition, a colored encapsulant sheet having excellent physical properties with respect to molding characteristics is obtained.

(Base resin)
As the base resin for the transparent outermost layer, the low density polyethylene (LDPE), the linear low density polyethylene (LLDPE), or the metallocene linear low density polyethylene (like the base resin of the colored intermediate layer sealing material composition) M-LLDPE) can be preferably used as appropriate.

The density of polyethylene resin can be used as a transparent outermost layer for the base resin, 0.870 g / cm ³ or more 0.900 g / cm ³ or less, preferably, 0.870 g / cm ³ or more 0.890 g / cm ³ or less It is. The density of the transparent outermost layer base resin is preferably lower than that of the colored intermediate layer base resin. By setting the density of the base resin for the transparent outermost layer in the above range, a colored encapsulant sheet having sufficient molding characteristics can be obtained while maintaining the heat resistance of the colored encapsulant sheet.

As the base resin for the transparent outermost layer, the crosslinking treatment by the irradiation of ionizing radiation, the dynamic viscoelasticity of the transparent outermost layer in the temperature of the transparent outermost melting point + 20 ℃ (Tanδ), be 10 ² or more Resin that can be used. Thereby, the molding characteristics of the colored sealing material sheet can be maintained within a preferable range.

  On the other hand, the transparent outermost layer base resin is preferably a polyethylene resin in which the number of full double bonds remaining in the composition stage is relatively smaller than the number of full double bonds of the colored intermediate layer base resin. . Further, the number of full double bonds in the transparent outermost layer base resin is preferably 0 or more and 1.0 or less, and more preferably 0 or more and 0.5 or less.

  By limiting the number of full double bonds of the base resin for the transparent outermost layer to the above range in combination with the base resin for the colored intermediate layer, it is possible to appropriately suppress crosslinking by irradiation with ionizing radiation and The molding characteristics of the stopping material sheet can be maintained in a preferable mode. When the number of full double bonds of the base resin for the transparent outermost layer exceeds 0.5, it is not preferable because the molding characteristics deteriorate due to the progress of crosslinking.

(Adhesive copolymer resin)
It is more preferable that the sealing composition for the transparent outermost layer contains an adhesive copolymer resin represented by a silane-modified polyethylene resin in addition to the base resin for the transparent outermost layer. The adhesive copolymer resin in the present invention is not necessarily limited to a silane-modified polyethylene resin as long as the adhesiveness improving component is a resin that has been polymerized in advance. Other epoxy-modified, polyethylene-based resins modified with unsaturated carboxylic acid or derivatives thereof may be used. Examples of unsaturated carboxylic acids include maleic acid, itaconic acid, and fumaric acid. Examples of derivatives thereof include maleic acid monoester, maleic acid diester, maleic anhydride, itaconic acid monoester, itaconic acid. Examples thereof include esters and anhydrides such as diester, itaconic anhydride, fumaric acid monoester, fumaric acid diester, and fumaric anhydride. However, a silane-modified polyethylene resin can be particularly preferably used from the viewpoints of compatibility with the base resin and adhesion with other solar cell module components such as a glass substrate. Hereinafter, the case where the adhesive copolymer resin is a silane-modified polyethylene resin will be described in detail.

(Silane-modified polyethylene resin)
The silane-modified polyethylene resin is a resin obtained by graft polymerizing low-density polyethylene as a main chain, preferably linear low-density polyethylene, with an ethylenically unsaturated silane compound as a side chain. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to adhesion, it can improve the adhesion of the colored encapsulant sheet to other members in the solar cell module. The silane-modified polyethylene resin in the present specification refers to, for example, a silane-modified polyethylene resin that can be produced by the following production method, and at least a part of a linear low-density polyethylene resin that becomes a main chain. Is a concept indicating a resin obtained by graft polymerization with an ethylenically unsaturated silane compound. The resin as a main chain of the above, as with the base resin, it is preferred that the density 0.870 g / cm ³ or more 0.900 g / cm ³ or less of the polyethylene resin.

The silane-modified polyethylene resin can be produced, for example, by the following method. The desired reaction of one or more α-olefins, one or more ethylenically unsaturated silane compounds and, if necessary, one or more other unsaturated monomers using the container, for example, a pressure 500~4000Kg / cm ^2-position, preferably, 1000~4000Kg / cm ^2-position, temperature, 100 to 400 ° C.-position, preferably under the conditions of 150 to 350 ° C.-position, the radical polymerization In the presence of an initiator and, if necessary, a chain transfer agent, random copolymerization is performed simultaneously or stepwise, and further, the silane compound portion constituting the random copolymer formed by the copolymerization is modified. Or it can be condensed to produce a silane-modified polyethylene resin.

  As the polyethylene-based resin of the main chain, it is preferable to use linear low-density polyethylene that is an ethylene-α-olefin copolymer, and it is more preferable to use metallocene-based linear low-density polyethylene. Metallocene linear low density polyethylene is synthesized using a metallocene catalyst which is a single site catalyst. Such polyethylene has few side chain branches and a uniform comonomer distribution. For this reason, molecular weight distribution is narrow, it is possible to make it the above ultra-low density, and a softness | flexibility can be provided with respect to a colored sealing material sheet. As a result of the flexibility imparted to the colored encapsulant sheet, adhesion between the colored encapsulant sheet and a transparent front substrate such as glass can be enhanced.

  As the α-olefin of the linear low density polyethylene, an α-olefin having no branch is preferably used. Among these, 1-hexene and 1-heptene which are α-olefins having 6 to 8 carbon atoms are preferable. Or 1-octene is particularly preferably used. When the number of carbon atoms of the α-olefin is 6 or more and 8 or less, the colored sealing material sheet can be given good flexibility and good strength. As a result, the adhesion between the colored encapsulant sheet and the transparent front substrate such as glass is further enhanced.

  Examples of ethylenically unsaturated silane compounds to be graft polymerized with linear low density polyethylene include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane , One or more selected from vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane be able to.

  The graft amount, which is the content of the ethylenically unsaturated silane compound in the silane-modified polyethylene resin, is 0.001 to 15% by mass, preferably 0.01 to 5% by mass in the base resin of the silane-modified polyethylene resin. %, Particularly preferably 0.05 to 2% by mass. In the present invention, when the content of the ethylenically unsaturated silane compound is large, the mechanical strength and heat resistance are excellent. However, when the content is excessive, the tensile elongation and the heat fusion property tend to be inferior.

  Content in the sealing material composition for transparent outermost layers of the silane modified polyethylene resin used for the sealing material composition for the transparent outermost layer of the colored sealing material sheet of the present invention is the base resin of the sealing material composition The content in 100 parts by mass of the resin component composed of the adhesive copolymer resin is preferably 8 parts by mass or more and 20 parts by mass or less. In the present invention, if the content of the silane-modified polyethylene resin is 8 parts by mass or more, it is excellent in mechanical strength and heat resistance, but if the content is excessive, it tends to be inferior in tensile elongation and heat-fusibility. It is in.

  By using the silane-modified polyethylene-based resin described above as a component of the sealing material composition for the outer layer among the sealing material composition for the solar cell module, it has excellent adhesion, strength, durability, etc., and A colored encapsulant sheet having excellent weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, yield resistance, and other characteristics can be obtained. Various effects can be obtained in this way by using a silane-modified polyethylene resin. In particular, the colored encapsulant sheet is extremely effective without being affected by manufacturing conditions such as thermocompression bonding for manufacturing a solar cell module. The point which can provide the outstanding heat-fusion property, ie, the outstanding adhesiveness with the glass base material etc. which comprise a solar cell module, can be mention | raise | lifted as a biggest advantage.

[Other additives]
Each of the encapsulant compositions for the colored intermediate layer and the transparent outermost layer can appropriately contain the following additives.

(Crosslinking agent)
Each of the encapsulant compositions for the colored intermediate layer and the transparent outermost layer can appropriately contain a crosslinking agent. A well-known thing can be used for a crosslinking agent, It does not specifically limit, For example, a well-known radical polymerization initiator can be used. Examples of radical polymerization initiators include hydroperoxides such as diisopropylbenzene hydroperoxide and 2,5-dimethyl-2,5-di (hydroperoxy) hexane; di-t-butyl peroxide, t-butyl Cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-peroxy) hexyne-3, etc. Dialkyl peroxides; diacyl peroxides such as bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, benzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dichlorobenzoyl peroxide; t-butyl peroxyacetate, t-butyl pero Ci-2-ethylhexanoate, t-butyl peroxypivalate, t-butyl peroxyoctoate, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoate, di-t-butyl peroxyphthalate, 2 , 5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexyne-3, t-butylperoxy-2-ethylhexyl carbonate Oxyesters; organic peroxides such as ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide, or azo compounds such as azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile), dibutyltin Diacetate, dibutyltin dilaurate It can be mentioned dibutyltin dioctoate, dioctyltin dilaurate, dicumyl peroxide, such a silanol condensation catalyst.

  As content of a crosslinking agent, it is preferable that it is content of 0 mass part or more and 0.5 mass part or less with respect to a total of 100 mass parts of all the resin components of a sealing material composition, More preferably, it is 0.02. The range is not less than 0.5 parts by mass. By adding 0.02 parts by mass or more of a crosslinking agent, more preferable heat resistance can be imparted to the polyethylene resin used in the colored sealing material sheet of the present invention. On the other hand, when the addition amount of the cross-linking agent exceeds 2.0 parts by mass, the progress of cross-linking in the cross-linking step becomes excessive, and molding characteristics become insufficient, which is not preferable.

(Crosslinking aid)
Each of the encapsulant compositions for the colored intermediate layer and the transparent outermost layer can appropriately contain a crosslinking aid. As a crosslinking aid, a polyfunctional monomer having a carbon-carbon double bond and / or an epoxy group can be preferably used. More preferably, the cross-linking aid is one in which the functional group of the polyfunctional monomer is an allyl group, a (meth) acrylate group, or a vinyl group. By adding such a crosslinking aid, it is possible to reduce the crystallinity of the low density polyethylene and obtain a crosslinked colored sealing material sheet having excellent low temperature flexibility.

  Specifically, polyallyl compounds such as triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, diallyl maleate, trimethylolpropane trimethacrylate (TMPT), trimethylolpropane triacrylate (TMPTA) , Ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, etc. ) An acryloxy compound, a glycidyl methacrylate containing a double bond and an epoxy group, 4-hydroxybutyl acrylate glycidyl ether and 1, containing two or more epoxy groups - hexanediol diglycidyl ether, and 1,4-butanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, an epoxy-based compounds such as trimethylolpropane polyglycidyl ether. These may be used alone or in combination of two or more.

  Among these, tricyclodecane dimethanol diacrylate, which has a particularly high effect of improving adhesion to the glass surface, has good compatibility with low density polyethylene, and can be expected to improve heat resistance, can be particularly preferably used. The content of the crosslinking aid is preferably 0.01 parts by mass or more and 3 parts by mass or less, more preferably 0.05 parts by mass with respect to 100 parts by mass in total of all resin components of the sealing material composition. It is the range below 2.0 parts by mass. In addition, about these crosslinking adjuvants, it can contribute to adjustment to the said preferable range of MFR ratio of each layer by making it contain only in a colored intermediate | middle layer.

(Adhesion improver)
In each of the encapsulant compositions for the colored intermediate layer and the transparent outermost layer, the adhesion durability with other substrates can be further improved by adding an adhesion improver as appropriate. . As the adhesion improver, a known silane coupling agent can be used. The silane coupling agent is not particularly limited. For example, vinyl-based silane coupling agents such as vinyltrichlorosilane, vinyltrimethoxysilane, and vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxypropyldiethoxy. A methacryloxy-based silane coupling agent such as silane or 3-methacryloxypropyltriethoxysilane can be preferably used. In addition, these can also be used individually or in mixture of 2 or more types.

  When adding a silane coupling agent as an adhesion improver, the content is 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass in total of all resin components of the sealing material composition. Yes, and the upper limit is preferably 5.0 parts by mass or less. When the content of the silane coupling agent is in the above range, and the polyolefin resin constituting the encapsulant composition contains an appropriate amount of the ethylenically unsaturated silane compound, the adhesion is more preferable. And improve. In addition, when this range is exceeded, the film-forming property is deteriorated, or the silane coupling agent is aggregated and solidified over time, and so-called bleed out may occur, which is not preferable. .

(Radical absorbent)
In each encapsulant composition for the colored intermediate layer and the transparent outermost layer, the degree of cross-linking is further increased by using the above-mentioned cross-linking auxiliary agent serving as a radical polymerization initiator and the radical absorbent for quenching it in combination. It can be finely adjusted. Examples of such radical absorbents include hindered phenol-based antioxidants, hindered amine-based weather resistance stabilization, and the like. A hindered phenol-based radical absorbent having a high radical absorbing ability near the crosslinking temperature is preferred. The amount of the radical absorbent used is preferably 0.01 parts by mass or more and 3 parts by mass or less, more preferably 0.05 parts by mass or more, with respect to 100 parts by mass in total of all resin components of the encapsulant composition. It is the range of -2.0 mass parts or less.

(Other ingredients)
Each sealing material composition for the colored intermediate layer and the transparent outermost layer may further contain other components. For example, components such as a weather resistance masterbatch for imparting weather resistance to the colored sealing material sheet, various fillers, a light stabilizer, an ultraviolet absorber, and a heat stabilizer are exemplified. These contents vary depending on the particle shape, density, and the like, but are in the range of 0.001 part by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of all the resin components of each sealing material composition It is preferable to be within. By including these additives, it is possible to impart a mechanical strength that is stable over a long period of time, an effect of preventing yellowing, cracking, and the like to the colored sealing material sheet.

  A weatherproof masterbatch is obtained by dispersing a light stabilizer, an ultraviolet absorber, a heat stabilizer and the above-mentioned antioxidant in a resin such as polyethylene, and this is added to each sealing material composition. Thus, good weather resistance can be imparted to the colored encapsulant sheet. The weatherproof masterbatch may be prepared and used as appropriate, or a commercially available product may be used. As resin used for a weatherproof masterbatch, the polyethylene-type resin used as a base resin for this invention may be sufficient, and said other resin may be sufficient.

<Colored encapsulant sheet>
The colored encapsulant sheet of the present invention includes a colored intermediate layer, and a transparent outermost layer disposed on each outermost layer of the encapsulant sheet on either one of the colored intermediate layers, preferably both sides. It is the multilayer sealing material sheet comprised by the layer. Hereinafter, as a preferred embodiment of the present invention, referring to FIG. 1, a colored encapsulant sheet 1 having a three-layer structure including a transparent outermost layer of two layers each above and below a single colored intermediate layer. Will be described. However, the present invention is not limited to this embodiment.

As shown in FIG. 1, the colored sealing material sheet 1 has a colored intermediate layer 11, and transparent outermost layers 12 are disposed on both surfaces of the colored intermediate layer 11. The dynamic viscoelasticity of each of these layers is adjusted to a specific range unique to the present application. Specifically, the value of the dynamic viscoelasticity (Tanδ) of the transparent outermost layer at the melting point of the transparent outermost layer + 20 ° C. is A, and the dynamic of the colored intermediate layer at the temperature of the melting point of the colored intermediate layer + 20 ° C. when the value of viscoelasticity (Tan?) is B, the ratio between a and B (a / B) has a range of 10 ² to 10 ⁶ or less. The dynamic viscoelasticity (Tan δ) at a temperature of the melting point of the colored intermediate layer + 20 ° C. is preferably from 0.1 to 1.0, and the dynamic viscoelasticity at the temperature of the melting point of the transparent outer layer + 20 ° C. Tan δ) is preferably 10 ² or more and 10 ⁵ or less.

  In addition, for example, a colored sealing material sheet having a two-layer structure in which the transparent outermost layer 12 is disposed only on one side of the colored intermediate layer, or the colored intermediate layer 11 has a multilayer structure, and other functional layers in the colored intermediate layer. Even if it is the colored sealing material sheet | seat in which this is arrange | positioned, it is equipped with the colored intermediate | middle layer and transparent outermost layer which satisfy | fill the predetermined condition as described in this specification, and is colored sealing provided with the other structural requirements of this invention Any material sheet is within the scope of the present invention.

  The colored intermediate layer 11 is a layer constituting a main part as a substrate layer in the colored sealing material sheet 1. Moreover, the coloring material for expressing a desired color is contained in the external appearance of the colored sealing material sheet 1 only in this layer. And the colored intermediate | middle layer 11 is provided with sufficient heat resistance by fully advancing the bridge | crosslinking by irradiation of ionizing radiation, and, thereby, the colored sealing material sheet 1 is durable as a structural member of a solar cell module. It has a nature.

  The dynamic viscoelasticity (Tanδ) of the colored intermediate layer 11 at a melting point + 20 ° C. is preferably 0.1 or more and 1.0 or less. If the dynamic viscoelasticity (Tan δ) is less than 0.1, the molding characteristics during the integration step may be insufficient, which is not preferable. On the other hand, if it exceeds 1.0, the wraparound may not be sufficiently prevented or sufficient heat resistance may not be maintained.

  Since the colored intermediate layer 11 is whitened with a coloring material such as a white pigment, the power generation efficiency of the solar cell module configured using the colored sealing material sheet 1 is significantly improved. In terms of improving the power generation efficiency, it is desirable to whiten the colored intermediate layer 11. However, in addition to the white color, for example, yellow, green, You may make it light blue etc., and the same effect can be acquired also in that case, respectively.

  Further, by coloring the colored intermediate layer 11 in a desired color, harmony in the color tone of the mounting body for fixing the solar cell module using the colored sealing material sheet 1, for example, a wall or a roof of a building Can contribute to the improvement of the design. By setting it as such a colored sealing material sheet, the design property and the improvement of power generation efficiency can be made compatible.

  The transparent outermost layer 12 is a layer that is disposed on the outermost surface of the encapsulant sheet in the colored encapsulant sheet 1 and constitutes a subordinate portion as a surface material. The transparent outermost layer 12 is imparted with preferable flexibility by appropriately suppressing cross-linking, whereby the colored sealing material sheet 1 is molded at the time of the integration step as a solar cell module, and other members. It has excellent adhesiveness. In addition, although the colored sealing material sheet 1 of this invention is provided with a colored external appearance, this transparent outermost layer 12 does not contain a coloring material.

The dynamic viscoelasticity (Tanδ) of the transparent outermost layer 12 at a melting point + 20 ° C. is preferably 10 ² or more and 10 ⁵ or less. The dynamic viscoelasticity (Tan?) Is less than 10 ^2, may molding characteristics at the integration step may become insufficient undesirably. If it exceeds ^105, which is not preferable when it can not hold a sufficient heat resistance. The upper limit of the dynamic viscoelasticity (Tanδ) is small in variation in dynamic viscoelasticity (Tanδ) at the time of heat treatment such as thermal lamination, the production stability is relatively easy to manage, and From the viewpoint that the molding characteristics and the function of preventing wraparound can be harmonized in a balanced manner, it is more preferably 10 ³ or less.

  The colored encapsulant sheet 1 has a structure in which the transparent outermost layer 12 is laminated on the outermost layer, so that the colored portion at the time of integration as a solar cell module, that is, the solar cell element 3 of the colored intermediate layer 11. Can be prevented from entering the light receiving surface. This effect is that the transparent outermost layer 12 blocks unnecessary movement when the colored intermediate layer 11 is melted, and even if the molten transparent outermost layer 12 slightly wraps around the light receiving surface side of the solar cell element. Since the portion is transparent, the power generation efficiency of the solar cell module is not reduced, and this is due to the two effects described above.

  The total thickness of the colored encapsulant sheet 1 including the colored intermediate layer 11 and both transparent outermost layers 12 is preferably 100 μm or more and 1000 μm or less, and more preferably 200 μm or more and 600 μm or less. If the thickness is less than 100 μm, the impact cannot be sufficiently mitigated, and if it exceeds 1000 μm, no further effect such as impact relaxation can be obtained, which is uneconomical. In addition, the colored sealing material sheet of the present invention is a thin film having a thickness of about 500 μm or less because the outer layer has flexibility and the inner layer has heat resistance, thereby suppressing flow out and film thickness change during the lamination process. Even in such a case, it is possible to provide sufficiently preferable molding properties, heat resistance, and solar cell element protection performance.

  About the ratio of the thickness of each layer in the colored sealing material sheet 1, the thickness ratio of the transparent outermost layer 12: the colored intermediate layer 11: the transparent outermost layer 12 is in the range of 1: 2: 1 to 1: 30: 1. It is preferable that By setting the thickness ratio of each layer within this range, the heat resistance and molding characteristics of the colored encapsulant sheet 1 can be maintained within a favorable range.

  About MFR of each layer in the colored sealing material sheet 1, the MFR of each layer at 190 ° C. and a load of 2.16 kg measured according to JIS K6922-2 is about 0.1 g / 10 min to 0.5 g / 10 min. It is preferable to converge in the range. As described above, the dynamic viscoelasticity (Tan δ) is largely separated between the colored intermediate layer 11 and the transparent outermost layer 12, but the MFR of each layer by cross-linking treatment by irradiation with ionizing radiation is as follows. One of the characteristics in the physical properties of the sealing material sheet of the present invention is that it converges to the above low MFR range. It is considered that this characteristic physical property contributes to both molding characteristics and heat resistance as a sealing material sheet.

  In the colored encapsulant sheet 1 described above, the individual “dynamic viscoelasticity (Tanδ) at a temperature of melting point + 20 ° C.” according to the above definition for each layer of the colored intermediate layer 11 and the transparent outermost layer 12. For example, it can be specified by the following measurement method. That is, the transparent resin on the outermost layer side of the colored encapsulant sheet 1 and the colored resin closer to the inner layer are cut out to a thickness of about 5 to 10 μm and re-sheeted with a hot press for measurement. The dynamic viscoelasticity (Tanδ) of each layer can be specified by measuring the dynamic viscoelasticity (Tanδ) of the sample.

<Method for producing colored sealing material sheet>
The colored encapsulant sheet of the present invention is formed by, for example, a production method in which the encapsulant composition for each layer is formed into a multilayer sheet by melt formation, and the multilayer sheet after the melt formation is subjected to crosslinking treatment by irradiation with ionizing radiation. Can be obtained.

[Sheet making process]
The melt molding of each composition for the colored intermediate layer and the transparent outermost layer is a molding method usually used in ordinary thermoplastic resins, that is, various moldings such as injection molding, extrusion molding, hollow molding, compression molding, and rotational molding. Done by law. As an example of the forming method as the multilayer sheet, a method of forming by co-extrusion using two or more types of melt-kneading extruders can be given.

  The lower limit of the molding temperature at the time of molding may be a temperature exceeding the melting point of each sealing material composition. The upper limit of the molding temperature is the temperature at which crosslinking does not start during film formation, that is, the temperature at which the gel fraction of the encapsulant composition can be maintained at 0%, depending on the 1 minute half-life temperature of the crosslinking agent used. Is preferred. Here, in the manufacturing method of the colored sealing material sheet of the present invention, a crosslinking agent is not essential in the sealing material composition, and even when a crosslinking agent is added, the content is 0.5% by mass. It is preferable to make it less than. As a result, under the normal low-density polyethylene resin molding temperature, for example, under heating conditions of about 120 ° C., the gel fraction does not change, and crosslinking that substantially affects the physical properties of the resin does not proceed. Can be. According to the production method of the present invention capable of maintaining the gel fraction of the encapsulant composition during film formation at 0%, the load on the extruder or the like during film formation is reduced, and the colored encapsulant sheet It is possible to increase productivity.

[Crosslinking process]
A cross-linking step of performing cross-linking treatment by ionizing radiation on the uncross-linked colored encapsulant sheet after the sheet forming step is integrated with other members after completion of the sheet forming step. Before starting the solar cell module integration process.

  Regarding the crosslinking treatment by irradiation with ionizing radiation, the individual crosslinking conditions are not particularly limited. Unlike the conventional method, the method for producing a colored encapsulant sheet of the present invention basically optimizes the degree of cross-linking by limiting physical properties on the composition side, without fine adjustment of irradiation conditions. It is because it is a method to do. As a general guideline of specific irradiation amount, it may be appropriately set so that the gel fraction of the colored intermediate layer after the crosslinking treatment is in a range of about 10% or more. Specifically, it can be performed by ionizing radiation such as electron beam (EB), α-ray, β-ray, γ-ray, neutron beam, etc. Among them, it is preferable to use an electron beam. The acceleration voltage in electron beam irradiation is determined by the thickness of the sheet that is the object to be irradiated, and the thicker the sheet, the larger the acceleration voltage is required. For example, a 0.5 mm-thick sheet is irradiated with 100 kV or more, preferably 200 kV or more. If the acceleration voltage is lower than this, the colored intermediate layer does not sufficiently crosslink. The irradiation dose is in the range of 5 kGy to 500 kGy, preferably 5 to 200 kGy. When the irradiation dose is less than 5 kGy, the colored intermediate layer is not sufficiently crosslinked, and when it exceeds 500 kGy, there is a concern about deformation or coloring of the colored sealing material sheet due to the generated heat. Irradiation with ionizing radiation may be performed from one side or from both sides as long as the cross-linking of the colored intermediate layer can sufficiently proceed to the above-described level. Irradiation may be in an air atmosphere or a nitrogen atmosphere.

  Here, the gel fraction (%) means that 0.1 g of a colored encapsulant sheet is put in a resin mesh, extracted with 60 ° C. toluene for 4 hours, then taken out together with the resin mesh, weighed after drying treatment, and before and after extraction. Mass comparison is performed, the mass% of the remaining insoluble matter is measured, and this is used as the gel fraction.

  According to the production method of the present invention, by setting the irradiation conditions for optimizing the degree of crosslinking of the colored intermediate layer as described above, the degree of progress of crosslinking of the transparent outermost layer can be appropriately set under the irradiation conditions. Suppression can be achieved at the same time. For this reason, management of crosslinking conditions is easy, and productivity can be improved by releasing from complicated and complicated management of crosslinking conditions. Further, the setting of the irradiation condition is not necessarily limited to the gel fraction. For example, the thermal shrinkage rate after crosslinking of the sample sealing material sheet may be measured at an initial stage, the result may be fed back to the initial irradiation conditions, and thereafter irradiation may be continued under the same conditions. .

  This crosslinking treatment may be performed continuously in-line following the sheet forming step, or may be performed off-line. Further, when the crosslinking treatment is a general heat treatment, generally, the content of the crosslinking agent is 0.5 parts by mass or more and 1.5 parts by mass with respect to 100 parts by mass of all components of the colored sealing material sheet. Although the following is required, in the colored sealing material sheet of the present invention, the content of the cross-linking agent may be 0, and even if it is contained, it may be less than 0.5 parts by mass. preferable. Thereby, the risk of the productivity fall by gelatinization of the sealing material composition in the sheeting process of a sealing material composition can be reduced. In addition, since the colored sealing material sheet | seat of this invention obtained by doing in this way is bridge | crosslinked, the annealing process etc. of the second time etc. are unnecessary and can be used in a modularization process as it is.

<Solar cell module>
Next, a preferred embodiment of the solar cell module of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view showing an example of the layer structure of the solar cell module 10 according to an embodiment of the present invention. The solar cell module 10 includes a transparent front substrate 4, a transparent sealing material sheet 2 stacked on the light-receiving surface side of the solar cell element 3, the solar cell element 3, and the non-light-receiving of the solar cell element 3 from the light-receiving surface side of incident light. The colored sealing material sheet 1 and the back surface protective sheet 5 laminated on the surface side are laminated in order.

  As for the transparent encapsulant sheet 2, a conventionally known polyethylene-based transparent encapsulant can be used without any particular limitation, but the same low-density polyethylene resin as the encapsulant composition for the colored encapsulant sheet It is preferable that it is a transparent resin sheet which consists of a composition which uses as a base resin.

  The power generation efficiency of the solar cell module 10 can be improved by disposing the colored sealing material sheet 1 having light reflection performance on the non-light-receiving surface side of the solar cell element 3 in the solar cell module 10 as described above. In addition, the colored encapsulant sheet 1 is an encapsulant sheet that is particularly excellent in molding characteristics, that is, the ability to follow the unevenness of the opposing base material. The arrangement on the opposite lower surface, that is, the non-light-receiving surface side is extremely effective.

  The layer configuration of the solar cell module of the present invention is not limited to that according to the above embodiment. Since the colored encapsulant sheet 1 of the present invention has adhesion to both glass and metal, the solar cell modules having various configurations including the glass substrate and the metallic solar cell module are utilized by taking advantage of the characteristics. Can be used universally. For example, in a solar cell module, the colored sealing material sheet of the present invention is suitably used even when one surface of the sealing material sheet faces the metal surface and the other surface faces the glass layer. Can be used.

  The solar cell module 10 includes, for example, the above-described members including the colored encapsulant sheet 1 sequentially laminated so as to have the above-described configuration, and then integrated by vacuum suction or the like, and then a molding method such as a lamination method. Thus, the above-mentioned member can be manufactured by thermocompression molding as an integral molded body.

  In the solar cell module 10 of the present invention, the solar cell element 3, the transparent front substrate 4, and the back surface protective sheet 5 that are members other than the colored encapsulant sheet 1 and the transparent encapsulant sheet 2 are made of conventionally known materials. It can be used without particular limitation. Moreover, the solar cell module 10 of this invention may also contain members other than the said member.

  While the present invention has been specifically described with reference to the embodiment, the present invention is not limited to the above embodiment, and can be implemented with appropriate modifications within the scope of the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

<Manufacture of colored sealing material sheet>
The raw materials of the encapsulant composition described below are mixed in the proportions (parts by mass) shown in Table 1 below, and the composition for the colored intermediate layer and the composition for the transparent outermost layer of the colored encapsulant sheets of Examples and Comparative Examples are respectively used. It was a thing. Each sealing material composition is used for a colored intermediate layer and a transparent outermost layer at an extrusion temperature of 210 ° C. and a take-off speed of 1.1 m / min using a φ30 mm extruder and a film molding machine having a 200-mm width T-die. 3 layer structure uncrosslinked for preparing each resin sheet for the above, and laminating each of these resin sheets to form a colored encapsulant sheet of Examples and Comparative Examples having a colored intermediate layer and both transparent outermost layers A multilayer sheet was produced. The thickness of each colored encapsulant sheet in Examples and Comparative Examples was set to a total thickness of 600 μm. About the ratio of the thickness of each single layer forming the three-layer structure of Examples and Comparative Examples, the thickness ratio of the transparent outermost layer: the colored intermediate layer: the transparent outermost layer is 1: 4: 1.
However, the colored sealing material sheet of Comparative Example 5 was a single-layer sheet having a total thickness of 600 μm made of the following EVA resin (E).

The following raw materials were used as a sealing material composition raw material for molding each resin sheet for a sealing material.
Base resin for colored intermediate layer (denoted as “PE1” in the table, the same applies hereinafter): Metallocene having a density of 0.880 g / cm ³ , a melting point of 60 ° C., and an MFR at 190 ° C. of 3.5 g / 10 min. Linear low density polyethylene (M-LLDPE).
Base resin for transparent outermost layer (“PE2”): Metallocene linear low density polyethylene (M-LLDPE) having a density of 0.885 g / cm ³ , a melting point of 66 ° C., and an MFR at 190 ° C. of 18 g / 10 min. ).
EVA base resin ("E"): ethylene-vinyl acetate copolymer resin. VA = 28%
Silane-modified polyethylene resin (“S”): 2 parts by mass of vinyltrimethoxysilane with respect to 100 parts by mass of metallocene linear low density polyethylene having a density of 0.880 g / cm ³ and an MFR of 20 g / 10 min. A silane-modified polyethylene resin obtained by mixing 0.15 parts by mass of dicumyl peroxide as a radical generator (reaction catalyst), melting and kneading at 200 ° C. Density 0.880 g / cm ³ , MFR 13.0 g / 10 min. Melting point 60 ° C.
Weathering agent master batch 1 (“MB1”): 100 parts by weight of base resin for colored intermediate layer. 0.6 parts by mass of KEMISTAB62 (HALS). 3.5 parts by mass of KEMISORB 12 (UV absorber). 0.6 parts by mass of KEMISORB 79 (UA absorbent). CHIMASORB202 (UV absorber) 0.07 parts by mass. 2.14 parts by mass of tricyclodecane dimethanol diacrylate (crosslinking aid).
Weathering agent master batch 2 (“MB2”): 100 parts by weight of base resin for colored intermediate layer. Tricyclodecane dimethanol diacrylate (crosslinking aid) 2.04 parts by mass.
Weathering agent master batch 3 (“MB3”): 100 parts by mass of the transparent outermost base resin. 0.6 parts by mass of KEMISTAB62 (HALS). 3.5 parts by mass of KEMISORB 12 (UV absorber). 0.6 parts by mass of KEMISORB 79 (UV absorber). CHIMASORB 202 (UV absorber): 0.07 parts by mass.
White colorant ("W"): titanium oxide. The one having a particle diameter of 0.3 mmφ was added as a master batch so that the content in 100 parts by mass of the intermediate layer sealing material composition was 8.1 parts by mass.
However, for Comparative Examples 2 and 3, a white colorant was also added to the transparent outermost layer composition at the above ratio.
Moreover, about the comparative example 5, it added so that content of the white colorant in 100 mass parts of EVA base resin might be 8.1 mass parts.

  Next, the uncrosslinked multilayer sheet for the above example was irradiated on both sides with an acceleration voltage of 250 kV and an irradiation intensity of 40 kGy using an electron beam irradiation apparatus (product name EC250 / 15 / 180L, manufactured by Iwasaki Electric Co., Ltd.). A total of 80 kGy was irradiated to obtain a crosslinked encapsulant sheet, which was used as the colored encapsulant sheet of the example.

  About the uncrosslinked multilayer sheet for the above examples, the one not subjected to the above crosslinking treatment was uncrosslinked as it was, so that it was used as the colored sealing material sheet of Comparative Example 1.

  In addition, as described above, the sealing material sheet obtained by the same material composition and the same manufacturing process as in Comparative Example 1 is used as the colored sealing material sheet in Comparative Example 2 except that a white pigment is added to the outermost layer. did.

  Furthermore, what carried out the crosslinking process by said electron beam irradiation to the sealing material sheet of the comparative example 2 was used as the colored sealing material sheet of the comparative example 3.

  In addition, as the base resin for each layer, an uncrosslinked multilayer sheet using the colored intermediate layer base resin (PE1) was used as the colored sealing material sheet of Comparative Example 4.

<Measurement of dynamic viscoelasticity (Tanδ)>
The dynamic viscoelasticity (Tan δ) at the melting point + 20 ° C. of each layer of the colored sealing material sheet of Example and Comparative Example 1 was measured. The results are as shown in Table 2. As a reference example, the dynamic viscoelasticity (Tan δ) of each of the following general polyethylene resins (without crosslinking treatment) at the melting point + 20 ° C. was also measured under the same conditions as in the examples. The measurement of dynamic viscoelasticity (Tan δ) was performed using Rheogel E4000 manufactured by UBM Co., Ltd. as a measuring device, under a measurement condition of 10 Hz with a static load of 100 g and a temperature rising rate of 3 ° C./min. It performed on the sealing material sheet | seat sample cut into 5 mm length 20mm. In addition, in order to separately grasp the unique Tan δ of each layer, the dynamic viscoelasticity is individually measured according to the above-mentioned regulations for each single-layer sheet forming the three-layer structure of the colored sealing material sheet of the example. The value of Tan δ unique to each layer was used. For Example 1 and Comparative Example 3, ionizing radiation was irradiated under the same conditions in a state where the layers were peeled after the crosslinking treatment, and then peeled for each layer, and the dynamic viscoelasticity of each layer was measured in the same manner.
Reference Example 1: Low density polyethylene (LLDPE) having a density of 0.918 g / cm ³ and a melting point of 105 ° C.
Reference Example 2: High density polyethylene (HDPE) having a density of 0.963 g / cm ³ and a melting point of 135 ° C.

  From Table 2, the present results when compared with a general polyethylene resin (reference example) or a polyethylene resin (comparative example 1) having the same melting point as that of the example not subjected to crosslinking treatment by irradiation with ionizing radiation. The peculiarity of the behavior of Tan δ at the temperature exceeding the melting point of the resin constituting each layer of the sealing material sheet of the invention can be confirmed.

<Evaluation example>
On the glass substrate (white plate float semi-tempered glass JPT3.2 75 mm × 50 mm × 3.2 mm), the colored sealing material sheets of Examples and Comparative Examples 1 to 4 cut to a width of 15 mm are laminated, and 150 ° C., 18 minutes. Then, the sample was subjected to processing with a vacuum heating laminator to obtain a solar cell module evaluation sample using each colored sealing material sheet. These solar cell module evaluation samples were evaluated by measuring heat resistance, molding characteristics, and wraparound suppression effects under the following test conditions. The results are shown in Table 3.

[Heat-resistant creep test]
Two sheets of colored sealing material sheets of Examples and Comparative Examples cut to 7.5 × 5.0 cm were placed on a glass substrate (white plate float semi-tempered glass JPT3.2 150 mm × 150 mm × 3.2 mm), A glass substrate (white plate float semi-tempered glass JPT3.2 75 mm × 50 mm × 3.2 mm) is placed on top of each other and subjected to vacuum heating laminator treatment under the following thermal laminating conditions (a) to (d). The solar cell module evaluation sample was obtained for the comparative example. These solar cell module evaluation samples were subjected to a heat-resistant creep test under the following test conditions to evaluate heat resistance.
The measurement is performed by placing the above solar cell module evaluation sample vertically and leaving it at 120 ° C. for 12 hours, and determining the moving distance of the glass substrate (white plate semi-tempered glass JPT3.2 75 mm × 50 mm × 3.2 mm) after being left to stand. The measurement results were evaluated by the following evaluation criteria A to C.
(Thermal lamination conditions) (a) Vacuum drawing: 4.0 minutes
(B) Pressurization (0 kPa to 60 kPa): 10 seconds
(C) Pressure holding (60 kPa): 6.0 minutes
(D) Temperature 150 ° C
(Evaluation criteria) A: 0.5 mm or less
B: More than 0.5mm and less than 1.0mm
C: 1.0 mm or more

[Molding characteristics test]
On the same glass substrate (white float semi-tempered glass JPT3.2 984 mm × 1635 mm × 3.2 mm) as used in the heat-resistant creep test, the following transparent sealing material sheet, 60 solar cell elements below, In the same thermal laminating conditions (a) to (d) as in the above test, the various wirings of Examples, each colored sealing material sheet of Examples and Comparative Examples, and the following back surface protective sheet were sequentially arranged and laminated. A vacuum heating laminator treatment was performed to obtain solar cell module evaluation samples for the respective examples and comparative examples. About these solar cell module evaluation samples, molding characteristics were evaluated by visual observation according to the following evaluation criteria.
Solar cell element: 6-inch p-type single crystal, thickness 200 μm, arrangement 6 × 10
Various wirings: Tab wiring for interconnecting cells (width 2 mm x thickness 190 μm) and connection wiring to connection box (width 6 mm x thickness 270 μm)
Transparent encapsulant sheet: 1.0 part by mass of crosslinking agent (Luperox 101 Arkema Yoshitomi), 100 parts by mass of EVA (vinyl acetate content 28%, manufactured by Mitsui DuPont Polychemical, trade name EVAFLEX / EV250 grade) Agent (TAIC Nippon Kasei) 1.0 parts by weight, UV absorber: Ciba Japan Co., Ltd., trade name CHIMASORB81 0.3 parts by weight, weathering stabilizer (Ciba Japan Co., Ltd., trade name Tinuvin 770) 0 .3 parts by weight of a transparent sealing material sheet containing 0.5 parts by weight of a silane coupling agent (trade name KBM1003, manufactured by Shin-Etsu Chemical Co., Ltd.).
Back surface protection sheet: Toray PET, model number S10 188 μm was used. In addition, it was set as the transparent sheet for the convenience of confirmation of wraparound.
(Evaluation criteria) A: Completely follows the unevenness of the base material surface that the colored encapsulant sheet faces.
C: A part of the colored encapsulant sheet does not completely follow the unevenness of the substrate surface facing, and a poorly laminated portion occurs.

[Turning suppression test]
About the same sample for solar cell module evaluation as what was used for the above-mentioned molding characteristic test, the wraparound suppression effect test was evaluated by visual observation according to the following evaluation criteria.
(Evaluation criteria) A: The colored sealing material does not wrap around the cell and the wiring.
C: The colored encapsulant wraps around the cell and the wiring.

  The water vapor barrier properties of the colored sealing material sheets of Examples and Comparative Example 5 prepared by the above method were also measured according to JISK7129. The results are shown in Table 3.

  From Tables 1 to 3, the colored sealing material sheet of the present invention can sufficiently suppress wraparound, and also has heat resistance, molding characteristics, and water vapor barrier properties at a high level. I understand that there is.

DESCRIPTION OF SYMBOLS 1 Colored sealing material sheet 11 Colored intermediate layer 12 Transparent outermost layer 2 Transparent sealing material sheet 3 Solar cell element 4 Transparent front substrate 5 Back surface protection sheet 10 Solar cell module

Claims (7)

A colored encapsulant sheet for a solar cell module,
The colored sealing material sheet is a multilayer sheet in which a transparent outermost layer not containing a coloring material is laminated on a colored intermediate layer containing a coloring material,
The colored intermediate layer, the density of 0.870 g / cm ³ or more 0.970 g / cm ³ or less of the polyethylene resin as a base resin,
The transparent outermost layer, the density of 0.870 g / cm ³ or more 0.900 g / cm ³ or less of the polyethylene resin as a base resin,
The value of dynamic viscoelasticity (Tanδ) of the transparent outermost layer at a temperature of the melting point of the transparent outermost layer + 20 ° C. is A,
When the value of the dynamic viscoelasticity (Tanδ) of the colored intermediate layer at a temperature of the melting point of the colored intermediate layer + 20 ° C. of the colored intermediate layer is B,
Colored sealant sheet ratio of the said A B (A / B) is 10 ² to 10 ⁶ or less. The colored intermediate layer has a dynamic viscoelasticity (Tanδ) at a temperature of 20 ° C. of the colored intermediate layer of 0.1 to 1.0, and the transparent outermost layer has a melting point of the transparent outermost layer. The colored sealing material sheet according to claim 1, wherein the dynamic viscoelasticity (Tan δ) at a temperature of + 20 ° C. is 10 ² or more and 10 ⁵ or less. The colored sealing material sheet according to claim 1, wherein the transparent outermost layer has a dynamic viscoelasticity (Tan δ) at a temperature of the melting point of the transparent outermost layer + 20 ° C. of 10 ² or more and 10 ³ or less.   The colored sealing material sheet according to any one of claims 1 to 3, wherein the coloring material is a white coloring agent selected from the group consisting of calcium carbonate, barium sulfate, zinc oxide, and titanium oxide.   The colored sealing material sheet according to any one of claims 1 to 4, wherein the transparent outermost layer contains an adhesive copolymer resin made of a silane-modified polyethylene resin. It is a solar cell module provided with the colored sealing material sheet in any one of Claim 1 to 5, and a solar cell element,
The solar cell module in which the colored sealing material sheet is disposed only on the non-light-receiving surface side of the solar cell element. It is a manufacturing method of the colored sealing material sheet according to any one of claims 1 to 5,
The method for producing a colored encapsulant sheet in which the multilayer sheet is subjected to a crosslinking treatment by irradiation with ionizing radiation.

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