JP2019110175A - Rear surface protective sheet for solar cell module - Google Patents

Abstract

To provide a rear surface protective sheet capable of contributing to improvement of designability of solar cell module and improvement of generation efficiency, by forming a dark and easily adhesive layer on the surface of a white resin base material layer, and excellent in adhesiveness and blocking resistance in the manufacturing stage.SOLUTION: A manufacturing method of rear surface protective sheet includes a step of forming a dark and easily adhesive layer 12 by coating the surface of a white resin base material layer 11 with dark color aqueous primer coating liquid. The dark color aqueous primer coating liquid is an aqueous dispersion composed of acid modified polyolefin resin, an organic dark-color pigment permeating a near infrared ray having a wavelength of 750-1500 nm, and a wax, and a solvent where an aqueous medium is a main solvent, and the average grain size of the acid modified polyolefin resin in the aqueous dispersion is 1.0-2.5 times that of the organic dark-color pigment.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a back surface protection sheet for a solar cell module.

  BACKGROUND OF THE INVENTION In recent years, solar cells as clean energy sources have attracted attention due to rising awareness of environmental issues. Generally, in a solar cell module constituting a solar cell, a transparent front substrate, a sealing material sheet on the light receiving surface side, a solar battery element, a sealing material sheet on the non-light receiving surface side, and a back surface protection sheet are laminated in order from the light receiving surface It has a function to generate electricity when sunlight enters the solar cell element.

  By the way, there are cases where the solar cell module is required to have a black or a similar dark appearance (herein also collectively referred to as "dark" in the present specification) mainly for the purpose of improving the design. In this case, also for the back surface protection sheet disposed on the outermost surface of the above solar cell module, at least the surface on the light receiving surface side has a dark appearance similar to that of the other exposed portions. Is required.

  In order to meet such demands, various dark color systems that do not absorb near infrared rays, such as oxazine pigments, instead of conventional carbon black as a coloring material for coloring the back surface protection sheet for solar cell modules in a dark color There is proposed a dark ink prepared by blending the organic pigment of (1) and (2). A dark layer for satisfying design requirements is configured to contain these infrared-transmissible dark inks, thereby reflecting near-infrared rays transmitted through this layer such as a white resin base material and the like. By making it reflect by making it contribute to power generation, the appearance of dark color which is excellent in the designability can be given to the whole solar cell module, avoiding the fall of power generation efficiency.

  On the other hand, the back surface protection sheet has an essential role of preventing the penetration of moisture (water vapor) from the back surface side in the solar cell module. In order to achieve this, the back surface protection sheet is required to have high adhesion to the non-light receiving surface side sealing material sheet constituting the solar cell module. An easy-adhesion layer (primer layer) formed by containing a resin obtained by crosslinking an acrylic resin with a polyisocyanate compound, an additive such as a silane coupling agent, and the like on the surface of a base resin layer as one that can well meet this requirement. The back surface protection sheet which improved adhesiveness by forming is proposed (refer to patent documents 3).

  Here, in order to obtain a dark-colored back surface protection sheet excellent in adhesion and still satisfying the above-mentioned design requirements, the basic layer configuration is disclosed in Patent Document 3 and the back surface protection sheet. Similarly, the dark-colored organic pigment disclosed in Patent Document 1 or 2 is added to the easily adhesive layer in the back protective sheet, whereby a dark easy adhesive layer (primer layer) is formed on the surface of the back protective sheet. It is conceivable to form it.

  Generally, as an easily adhesive layer composition for forming the above easily adhesive layer on the surface of a resin base material, an organic solvent easy adhesive layer composition disclosed in Patent Document 3 is widely used. It is done. However, with regard to the adhesiveness to the olefin-based sealing material sheet, the easy-adhesion layer composition comprising the aqueous medium as the main solvent is more advantageous than the above-mentioned easy-adhesion layer composition of the organic solvent system. It has come to be known (see Patent Document 4).

  However, in the case of using an easily adhesive layer composition containing an aqueous medium as a main solvent in order to form an easily adhesive layer on the surface of a resin substrate, the adhesiveness with the sealant sheet is significantly improved. On the other hand, there has been a problem that blocking is likely to occur in the manufacturing stage.

JP, 2010-199555, A International Publication No. 2016/052641 International Publication No. 2012/133748 Unexamined-Japanese-Patent No. 2017-69469

  This invention is a back surface protection sheet which can contribute to the improvement of the designability and power generation efficiency of a solar cell module by forming the easily bonding layer of dark color in the surface of a white resin base material layer, An object of the present invention is to provide a back surface protection sheet for a solar cell module, which is excellent in adhesion to a sealing material sheet constituting a battery module and can sufficiently prevent occurrence of blocking in the manufacturing stage. .

  MEANS TO SOLVE THE PROBLEM As a result of repeating earnest research in order to solve the said subject, the present inventors at the time of manufacture of the easily adhesive layer composition of the dark color which makes an aqueous medium a main solvent, base resin and a pigment in an aqueous dispersion. The inventors have found that the above-mentioned problems can be solved by optimizing the particle size ratio, and the present invention has been completed. More specifically, the present invention provides the following.

  (1) A method for producing a back surface protection sheet for a solar cell module, comprising: a white resin base material layer; and a dark color adhesion layer formed on one side of the white resin base material layer, wherein the white resin A step of forming a dark easy adhesion layer by applying a dark aqueous primer coating solution on the surface of a substrate layer, the dark aqueous primer coating solution comprising an acid-modified polyolefin resin and an acid-modified polyolefin resin having a wavelength of 750 nm or more and 1500 nm or less An aqueous dispersion comprising an easily adhesive layer composition comprising an organic dark pigment transmitting an infrared ray, and a wax, and a solvent containing an aqueous medium as a main solvent, wherein the aqueous dispersion is the above-mentioned in the aqueous dispersion. The manufacturing method of a back surface protection sheet which makes the average particle diameter of acid-modified polyolefin resin 1.0 to 2.5 times the average particle diameter of the said organic type dark color pigment.

  (2) The organic dark color pigment contains a brown pigment and a phthalocyanine pigment, and the brown pigment is a benzimidazolone pigment, 4-[(2,5-dichlorophenyl) azo]. -3-hydroxy-N- (2,5-dimethoxyphenyl) -2-naphthalenecarboxamide, 1-[(4-nitrophenyl) azo] -2-naphthalenol, bis [3-hydroxy-4- (phenylazo) -2 -Naphthalene carboxylic acid] copper salt, C.I. I. Pigment Brown 7, N, N'-bis (2,4-dinitrophenyl) -3,3'-dimethoxy-1,1'-biphenyl-4,4'-diamine, 3,4,9,10-perylenetetracarboxylic acid Diimide, Δ2,2 ′ (1H, 1′H) -binaphtho [2,1-b] thiophene-1,1′-dione and N, N ′-(10,15,16,17-tetrahydro-5,10 , 15, 17-tetraoxo-5H-dinaphtho [2,3-a: 2'3'-i] carbazole-4,9-diyl) bis (benzamide), at least one or more pigments selected from the group consisting of The manufacturing method of the back surface protection sheet as described in (1).

  (3) The wax is paraffin wax, and the content of the paraffin wax to the resin component in the easily adhesive layer composition is 10% by mass or more and 38% by mass or less in solid content conversion ratio (1) or The manufacturing method of the back surface protection sheet as described in 2).

  (4) The back surface protection sheet according to any one of (1) to (3), wherein the solvent contains an organic solvent as an auxiliary solvent in a content range of less than 50 parts by mass per 100 parts by mass of the solvent. Manufacturing method.

  (5) The acid-modified polyolefin resin is ethylene-acrylic acid ester-maleic anhydride terpolymer or ethylene-methacrylic acid ester-maleic anhydride terpolymer, or a mixed resin thereof The manufacturing method of the back surface protection sheet in any one of (1) to (4).

  (6) The manufacturing method of the back surface protection sheet in any one of (1) to (5) whose base resin of the said white resin base material layer is polyester-based resin.

  (7) A step of bonding the back surface protection sheet produced by the production method according to any one of (1) to (6) to a sealing material sheet having an olefin resin as a base resin via the dark color easy adhesion layer A method of manufacturing a solar cell module, comprising:

  According to the present invention, the back surface protection sheet can contribute to the improvement of the designability and the power generation efficiency of the solar cell module by forming the dark-colored easy-adhesion layer on the surface of the white resin base layer. It is possible to provide a back surface protection sheet for a solar cell module, which is excellent in adhesion to a sealing material sheet constituting the solar cell module, and can sufficiently prevent occurrence of blocking in the manufacturing stage. .

It is sectional drawing which shows typically an example of the laminated constitution of the solar cell module using the back surface protection sheet of this invention. It is sectional drawing which shows the laminated constitution of the back surface protection sheet of this invention.

<Solar cell module>
First, the whole structure of the solar cell module 10 using the back surface protection sheet 1 for solar cell modules of this invention is demonstrated. As shown in FIG. 1, the solar cell module 10 includes, from the light receiving surface side, the transparent front substrate 4, the sealing material sheet 3 on the light receiving surface side, the solar cell element 5, the sealing material sheet 2 on the non-light receiving surface side, and the back surface protection It consists of a structure where the sheet | seat 1 was laminated | stacked in order. In addition, a metal frame 6 made of aluminum or the like is usually installed on the side peripheral surface of the laminate.

  In the solar cell module 10, the back surface protection sheet 1 is disposed with the dark color easy adhesion layer 12 directed to the side of the non-light receiving surface on which the sealing material sheet 2 is bonded. Thereby, the adhesiveness between the sealing material sheet 2 on the non-light receiving surface side and the back surface protection sheet 1 is improved. Moreover, since this back surface protection sheet 1 is also excellent in blocking resistance, the handling property at the sheet stage before integration as the solar cell module 10 can be improved, and the productivity of the solar cell module can also be improved. .

  A transparent glass plate is usually used as the transparent front substrate 4 constituting the solar cell module 10, but a transparent resin sheet having weather resistance can also be used. Further, as the sealing material sheet 3 on the light receiving surface side and the sealing material sheet 2 on the non-light receiving surface side, a resin composed of an ethylene-vinyl acetate copolymer resin (EVA) or an olefin resin such as polyethylene is usually used. A sheet is used. Since the back surface protective sheet 1 is particularly excellent in the adhesiveness to EVA, it is particularly preferable that the sealing material sheet is a resin sheet made of EVA.

  Here, the sealing material sheet 3 on the light receiving surface side constituting the solar cell module 10 is usually transparent or translucent. Therefore, the solar cell module 10 can visually recognize the color of the back surface protection sheet 1 from the part of the clearance gap of the solar cell element 5 in planar view from the transparent front substrate 4 side. The surface of the solar cell element 5 is often dark in color, so by using the back surface protection sheet 1 of the present invention for the solar cell module 10, the appearance of the gap portion where the solar cell element 5 is not disposed and The difference in color from the appearance of the surface of the solar cell element can be reduced, and the appearance can be configured by the blackness having a uniform feel, and the designability of the solar cell module 10 can be improved.

In the present invention, “dark color” refers to “color” in which the range of L ^* value, a ^* value and b ^* value in color coordinates is in the following specific range, and black is naturally included in this . Specifically, the specific range is a range of CIE color coordinates by standard light source D65, which is measured in accordance with JIS Z 8722, in a range of −1 ≦ a ^* ≦ 2.5 and −2 ≦ b ^* ≦ 0.5. The color in this range is referred to as "dark" in the present specification.

  Moreover, the solar cell module resulting from the absorption of the near infrared rays in the same layer by making the dark-colored easy-adhesion layer 12 of the back surface protection sheet 1 shown in FIG. 2 into an infrared ray transmitting layer transmitting near infrared rays of 750 nm to 1500 nm wavelength It is possible to avoid the reduction of ten generation efficiency. In addition, by using the white resin base layer 11 as the base material layer of the back surface protection sheet, the incident light from the near infrared ray of 750 nm to 1500 nm in wavelength transmitted through the dark easy adhesion layer 12 can be converted to this white resin base layer. It can be reflected at 11 and directed to the surface of the solar cell element 5 again, thereby further improving the power generation efficiency. In the present specification, “transmits a light beam having a wavelength of 750 nm to 1500 nm” means that a light beam having a wavelength of 750 nm to 1500 nm is transmitted 15% or more, preferably 50% or more, more preferably 60% or more. Shall mean.

[Method of manufacturing a solar cell module]
The solar cell module 10 can be manufactured by, for example, heat pressing and integrating each of the above-described components by vacuum thermal lamination processing. The lamination temperature at this time is preferably in the range of 110 ° C. or more and 190 ° C. or less, and more preferably 130 ° C. or more. The laminating time is preferably in the range of 5 minutes to 60 minutes. The laminating process is performed in a mode in which the dark-light-sensitive adhesive layer 12 of the back surface protective sheet 1 and the sealing material sheet made of the above-mentioned olefin resin are made to face each other and heated and pressure-bonded. Thereby, the high adhesiveness of the easily dark-colored adhesive layer 12 in the interface of the back surface protection sheet 1 and the sealing material sheet 2 by the side of a non-light-receiving surface can fully be expressed.

<Back side protection sheet>
The back surface protective sheet 1 of the present invention includes a white resin base layer 11 constituting a main portion of the back surface protective sheet 1 and a dark color easy adhesive layer 12 formed on one side of the white resin base layer 11. It is a resin sheet comprised.

  The thickness of the back surface protective sheet 1 is not particularly limited. However, the thickness of the white resin base layer 11 constituting the main part is preferably 35 μm or more and 350 μm or less, and more preferably 50 μm or more and 300 μm or less. Also, the thickness of the easy-to-adhere layer 12 may be suitably adjusted according to, for example, the required adhesive strength, the desired optical properties, and the designability (color tone of blackness), etc. The range of 15.0 μm or less is preferable.

[White resin base layer]
The white resin base material layer 11 can be comprised with the white resin sheet which shape | molded the resin composition containing a white pigment in sheet form. If necessary, additives such as an ultraviolet light absorber, a light stabilizer, an antioxidant, an antistatic agent, and a flame retardant may be further added to the resin composition.

  The white resin sheet which comprises the white resin base material layer 11 shape | molds said resin composition in a sheet form by well-known various molding methods, such as an extrusion method, T-die method, a cast molding method, an inflation method, etc. Can be obtained by Moreover, these resin sheets can be obtained by drawing the above-mentioned resin composition in a uniaxial or biaxial direction by a tenter method or a tubular method or the like, for example, a biaxially drawn resin sheet It may be polyethylene terephthalate or the like. In addition, in this specification, although the term "resin sheet" is used as a general term of what processed the above resin compositions to a sheet form, this term is used as a concept also including a resin film. Further, these resin sheets may have a single-layer structure, or may be a laminate composed of a plurality of layers laminated with a conventionally known adhesive or the like.

(Base resin)
Specifically as a base resin of the resin composition which forms the white resin base material layer 11, polyethylene terephthalate (PET), Preferably, the hydrolysis resistant polyethylene tephthalate (HR-PET which is excellent in heat resistance and hydrolysis resistance) is preferable. Or polyester resins such as polyethylene naphthalate (PEN) can be used.

(White pigment)
The resin composition forming the white resin base layer 11 contains a white pigment. As the white pigment, titanium oxide, calcium carbonate, barium sulfate, silicon dioxide or the like can be used. Among them, titanium oxide can be preferably used, among which titanium oxide which is a general-purpose product having a particle diameter of about 0.2 μm to about 0.5 μm. As a result, the white resin base layer 11 can be sufficiently provided with the function of efficiently reflecting near-infrared light. In addition, titanium oxide having a particle diameter of 0.8 μm or more and 1.2 μm or less can also be used, and according to this, the white resin base layer 11 can be provided with “a function to reflect near infrared rays extremely efficiently”. .

  The amount of the white pigment added to the white resin base layer 11 may be appropriately adjusted in accordance with the thickness of the white resin base layer 11. For example, when the thickness of the white resin base layer 11 is in the range of 50 μm or more and 200 μm or less, the content of the white pigment added to the resin composition forming this is 5 mass to the resin component of the same layer It is preferable that it is% or more and 40 mass% or less. If the content is less than the above ratio, "the function of efficiently reflecting near infrared light" tends to be insufficient, and if the content exceeds the above ratio, the film forming property may be reduced or bleed out, etc. While the decrease in the smoothness of the white resin base material layer 11 becomes a problem, the effect of improving the reflectance due to the addition thereof is not recognized.

  The above-mentioned "function for efficiently reflecting near-infrared light" more specifically means a function having an integral reflectance of 85% or more in a wavelength range of about 750 nm or more and 2200 nm or less. In addition, relative reflectance with the comparison standard sample is usually used for the above-mentioned reflectance. In the present invention, barium sulfate is used as a comparison standard sample. For the reflectance in the present invention, an integrating sphere attachment (for example, ISR 2200 manufactured by Shimadzu Corporation) is attached to a spectrophotometer (for example, Shimadzu Corporation UV 2450), barium sulfate is used as a standard plate, and a standard plate is 100 The relative reflectance as% is a measured value.

  In addition, the particle size of the white pigment is determined by photographing the primary particle size of the white pigment in a photograph using a transmission electron microscope (JEM-1230) manufactured by JEOL Ltd. A value obtained by performing statistical processing with distribution measurement software (MAC-View Ver. 3) is adopted. In calculating the particle size, the equivalent circle diameter based on volume is adopted. In addition, the particle size of the powder material of various resin in this specification or an inorganic filler shall mean the thing of the particle size measured by the said method.

[Dark easy adhesion layer]
The easy-to-adhere dark color layer 12 is a primer coat liquid in dark color having an aqueous medium as a main solvent described in detail below (herein referred to as "dark-colored aqueous primer coat liquid"), one side of the white resin base layer 11 It forms by apply | coating to the surface of, and solidifying the film which consists of a coating liquid apply | coated.

  Here, conventionally, in the formation of the easy adhesion layer (primer layer) on the resin sheet, as disclosed in, for example, JP 2013-74172 A, the easy adhesion layer composition is made of an organic solvent. An organic primer coating solution which has been dissolved or dispersed has been widely used. On the other hand, the back surface protection sheet of the present invention eliminates the use of the organic primer coating solution and replaces it with the aqueous primer coating solution, and improves the adhesion of the aqueous primer coating solution to the olefin resin. What maintained the effect and improved the blocking resistance which was the fault by optimizing the particle size ratio of the base resin and the pigment in the aqueous dispersion at the time of production of the easy adhesion layer composition It is.

(Base resin)
The easy adhesion layer composition contained in the dark aqueous primer coating solution used to form the dark easy adhesion layer 12 has an acid-modified polyolefin resin as a base resin, which comprises an olefin component and an unsaturated carboxylic acid component.

  The acid-modified polyolefin resin preferably has an MFR of 0.01 g / 10 min or more and less than 100 g / 10 min at 190 ° C. and a load of 2.16 kg measured in accordance with JIS K 7210. By using such an acid-modified polyolefin resin as a base resin, in the dark aqueous primer coating liquid used to form the dark easy adhesion layer 12, good dispersibility of the easy adhesion layer composition in the aqueous medium is maintained. It can be made easy.

  Also, by using an acid-modified polyolefin resin as a base resin, it is possible to form a dark-colored easy-adhesion layer 12 which is excellent in adhesion to an olefin-based resin forming the sealing material sheet 2 on the non-light receiving surface side. The easy-to-adhere dark-colored adhesive layer 12 of the present invention exhibits remarkable adhesion between, for example, the white resin base layer 11 made of polyester resin and the non-light-receiving side sealing material sheet 2 made of olefin resin. It is clear also from the description of, for example, Japanese Patent Application Laid-Open No. 2013-74172 that it can be improved.

  The olefin component as the main component of the acid-modified polyolefin resin is preferably an alkene having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 2-butene, 1-butene, 1-pentene, 1-hexene, etc. It may be a mixture of

  It is preferable that the unsaturated carboxylic acid component which carries out the acid modification of said olefin component is acrylic acid, methacrylic acid, etc. The content of these unsaturated carboxylic acid components in the acid-modified polyolefin resin is preferably 0.1% by mass to 10% by mass, and more preferably 0.2% by mass to 8% by mass. When the content of the unsaturated carboxylic acid component is less than 0.1% by mass, the dispersibility in the aqueous dispersion tends to be insufficient. On the other hand, when the content exceeds 10% by mass, the adhesiveness with the olefin-based resin forming the sealing material sheet 2 on the non-light receiving surface side and the water resistance tend to be lowered.

  Here, in preparation of a dark-colored aqueous | water-based primer coating liquid, acid-modified polyolefin resin is normally added to an aqueous solvent as a powder material refine | purified to arbitrary particle sizes. The average particle size of the finely powdered acid-modified polyolefin added to the aqueous dispersion in the dark aqueous primer coating solution is 1.0 times or more of the average particle size of the organic dark pigment in the aqueous dispersion 2.5. It is set to be not more than twice, preferably not less than 1.1 times and not more than 2.2 times. When the above particle size ratio is less than 1.0, that is, if the particle size of the organic dark pigment is relatively large, the adhesion due to the tendency of the coating film forming the dark easy adhesion layer 12 to become brittle becomes stronger And a decrease in blocking resistance due to excessive exposure of the same pigment on the surface of the easy-to-adhere layer 12. On the other hand, when the above particle size ratio exceeds 2.5, that is, the particle size of the base resin is relatively too large, the gaps between the base resin particles become large, and the mobility of the dark pigment excessively increases. The color transfer of the pigment to the encapsulant sheet or the like is likely to occur.

  The above "average particle diameter" refers to the average value of the primary particle diameter at the time of adding each of the purified powder materials to the aqueous solvent. For example, in the case of using “a pigment consisting of a mixture of a brown pigment and a phthalocyanine pigment (benzimidazolone phthalocyanine pigment)” as the organic dark color pigment, the average particle diameter of the pigment is 0.05 μm to 0.20 μm. It is an extent. Therefore, in this case, the average particle diameter of the acid-modified polyolefin resin in the dark aqueous primer coating solution, which is an aqueous dispersion, may be about 0.05 μm to 0.50 μm and about 0.06 μm to 0.44 μm. Is more preferred. Thus, the blocking resistance of the easily dark-colored adhesive layer 12 can be remarkably improved by optimizing and adjusting the particle size ratio.

  The average particle diameter of the acid-modified polyolefin resin is preferably 0.5 μm or less, and more preferably in the range of 0.06 μm or more and 0.44 μm or less, from the viewpoint of adhesion and dispersion stability. In addition, about the particle size of the powder material which consists of acid-modified polyolefin resin, in the case of the synthesis | combination from a raw material monomer, refinement | purification to an arbitrary particle size is possible by adjusting superposition | polymerization conditions suitably.

  The particle size of the acid-modified polyolefin resin and the particle size of the organic dark color pigment can be calculated by the same apparatus and method as the measurement of the particle size of the white pigment described above.

  The pH of the aqueous dispersion containing the acid-modified polyolefin resin is preferably in the range of pH 7 to 12 and more preferably in the range of pH 8 to 11 from the viewpoint of dispersion stability.

  More specifically, as the acid-modified polyolefin resin, ethylene-acrylic acid ester-maleic anhydride terpolymer, or ethylene-methacrylic acid ester-maleic anhydride terpolymer, or a mixed resin thereof It can be used preferably. In addition, ethylene- (meth) acrylic acid ester-(anhydride) maleic acid copolymer such as ethylene-butyl acrylate-(anhydride) maleic acid copolymer, ethylene-propylene-(meth) acrylic acid ester-(anhydride) Maleic acid copolymer, ethylene-butene- (meth) acrylic acid ester- (anhydride) maleic acid copolymer, propylene-butene- (meth) acrylic acid ester- (anhydride) maleic acid copolymer, ethylene-propylene- Butene-(meth) acrylic acid ester-(anhydride) maleic acid copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-maleic anhydride copolymer, ethylene-propylene-(anhydride) Maleic acid copolymer, ethylene-butene- (anhydride) maleic acid copolymer, propylene-butene- (anhydride) Maleic acid copolymer, ethylene - propylene - butene - can be used (anhydrous) maleic acid copolymers.

  The above-described acid-modified polyolefin resin can be processed into an aqueous dispersion by dispersing in an aqueous medium. As a method of dispersion, a known dispersion method such as a self emulsification method or a forced emulsification method may be adopted. As an aqueous dispersion containing an acid-modified polyolefin resin, an anionic aqueous dispersion obtained by neutralizing the unsaturated carboxylic acid component of the acid-modified polyolefin resin with an basic compound in an aqueous medium, It is preferable from the viewpoint of adhesiveness.

(Organic dark color pigment)
The dark-colored easy-adhesion layer 12 of the back surface protection sheet 1 transmits near-infrared light having a wavelength of 750 nm or more and 1500 nm or less while exhibiting a dark appearance. In order to form such a layer, an organic dark pigment having infrared transparency is added to the dark aqueous primer coating solution forming the dark easy-adhesive layer 12.

  As the organic dark pigment to be contained in the dark easy adhesion layer 12, various known organic pigments having infrared ray permeability can be appropriately used. However, in the back surface protection sheet 1 of the present invention, "a pigment comprising a mixture of a brown pigment and a phthalocyanine pigment" (hereinafter, this mixed pigment is referred to as "benzimidazolone phthalocyanine", which will be described in detail below) The pigment (also referred to as “pigment”) can be particularly preferably used. This “benzimidazolone phthalocyanine pigment” can provide the back surface protection sheet 1 with an excellent dark appearance and high infrared ray transparency.

  Among the pigment components contained in the above-mentioned “pigment consisting of a mixture of a brown pigment and a phthalocyanine pigment (benzimidazolone phthalocyanine pigment)”, the “brown pigment” may be a benzimidazolone pigment, 4 -[(2,5-dichlorophenyl) azo] -3-hydroxy-N- (2,5-dimethoxyphenyl) -2-naphthalenecarboxamide, 1-[(4-nitrophenyl) azo] -2-naphthalenol, bis [ 3-hydroxy-4- (phenylazo) -2-naphthalenecarboxylic acid] copper salt, N, N′-bis (2,4-dinitrophenyl) -3,3′-dimethoxy-1,1′-biphenyl-4, 4′-diamine, 3,4,9,10-perylenetetracarboxylic acid diimide, Δ2,2 ′ (1H, 1′H) -binaphtho [2,1-b] thiophene-1 1′-dione and N, N ′-(10,15,16,17-tetrahydro-5,10,15,17-tetraoxo-5H-dinaphtho [2,3-a: 2′3′-i] carbazole- At least one or more pigments selected from the group consisting of 4,9-diyl) bis (benzamide) can be used.

  Among the above-mentioned “brown pigments” used for “pigments consisting of a mixture of brown pigments and phthalocyanine pigments” (benzimidazolone phthalocyanine pigments), the dispersibility and adhesion of pigments in a dark aqueous primer coating solution From the viewpoint of maximizing the improvement effect, the “benzimidazolone-based pigment” can be particularly preferably used. The benzimidazolone-based pigment is a pigment having a benzimidazolone skeleton represented by the following general formula (1). Specifically, C.I. I. Pigment Yellow 120, C.I. I. Pigment Yellow 151, C.I. I. Pigment Yellow 154, C.I. I. Pigment Yellow 175, C.I. I. Pigment Yellow 180, C.I. I. Pigment Yellow 181, C.I. I. Pigment Yellow 194, C.I. I. Pigment Red 175, C.I. I. Pigment Red 176, C.I. I. Pigment Red 185, C.I. I. Pigment Red 208, C.I. I. Pigment Violet 32, C.I. I. Pigment Orange 36, C.I. I. Pigment Orange 62, C.I. I. Pigment Orange 72, C.I. I. Pigment Brown 25 etc., but not limited thereto. From the viewpoint of color gamut I. Pigment Brown 25 is more preferred.

  Among the pigment components contained in the above-mentioned “pigment consisting of a mixture of a brown-based pigment and a phthalocyanine-based pigment (benzimidazolone phthalocyanine pigment)”, the “phthalocyanine-based pigment” is a pigment having a phthalocyanine skeleton It is a concept including phthalocyanines in which various metals are coordinated. Specifically, C.I. I. Pigment Green 7, C.I. I. Pigment Green 36, C.I. I. Pigment Green 37, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 75 or C.I. I. Pigment Blue 15 and the like.

  When a "pigment consisting of a mixture of a brown-based pigment and a phthalocyanine-based pigment (benzimidazolone phthalocyanine pigment)" is used as the dark-colored aqueous primer coating solution for forming the dark-colored easily adhesive layer 12, the "brown-based pigment" in the pigment The content ratio of the pigment is 43 parts by mass or more and 233 parts by mass or less based on 100 parts by mass of the phthalocyanine based pigment (the content ratio of the brown based pigment to the phthalocyanine based pigment is in the range of 30:70 to 70:30 by mass ratio) It is preferable to set it as 66 mass parts or more and 150 mass parts or less (The content ratio of a brown-type pigment and a phthalocyanine-type pigment sets it as the range of 40:60-60:40 in mass ratio). By setting the content ratio of both pigments in such a range, it is possible to achieve both the design of the dark color of the back surface protective sheet 1 and the infrared transmittance at a higher level. Incidentally, the above-mentioned "pigment comprising a mixture of a brown pigment and a phthalocyanine pigment (benzimidazolone phthalocyanine pigment)" is particularly excellent in near infrared rays, in particular, infrared ray transmittance at a wavelength of 800 nm to 900 nm. It is as having been demonstrated also in the above-mentioned patent document 2, for example that it has an optical property.

  Here, as described above, the average particle diameter of the “pigment comprising a mixture of a brown pigment and a phthalocyanine pigment (benzimidazolone phthalocyanine pigment)” is about 0.05 μm to 0.20 μm. The present invention is not limited to this, and if the organic dark pigment to be contained in the easy-to-adhere adhesive layer 12 is determined, the average particle size of the acid-modified polyolefin resin in the dark aqueous primer coating solution is By optimizing the above, it is possible to formulate a dark aqueous primer coating solution capable of forming the dark easy adhesion layer 12 of the present invention.

  The content of the organic dark pigment in the dark aqueous primer coating solution is 0.03 to 0.50 as the solid content ratio (P / V ratio) other than the pigment / pigment in the easily adhesive layer composition. Preferably, it is 0.15 to 0.40. If the solid content ratio (P / V ratio) is less than 0.03, it is difficult to stably develop a uniform dark color even if the dispersion of the pigment is sufficiently increased. On the other hand, if the solid content ratio (P / V ratio) exceeds 0.35, the adhesion improving effect of the easy-to-adhere layer 12 may be inhibited, and the coating film forming the easy-to-under color layer 12 is It is not preferable because it tends to become brittle.

(Paraffin wax)
The back surface protective sheet 1 contains a wax material as an additive for improving the blocking resistance of the dark color adhesive layer 12. The wax material is preferably paraffin wax. By incorporating paraffin wax in an appropriate amount range in the dark easy-adhesion layer 12, the blocking resistance can be sufficiently improved while maintaining good adhesion while being formed using an aqueous primer coating solution. The effect of the present invention can be further improved to a preferable level. In addition, paraffin wax refers to all waxes having as a main component a linear paraffin hydrocarbon having 20 to 30 carbon atoms among organic waxes which are solid at normal temperature and become liquid when heated. And “Paraffin wax aqueous dispersion (Nippon Seiki Co., Ltd., EMUSTAR-0135)” can be mentioned as a specific example of the wax material which can be preferably used.

(Other additives)
In addition, as a non-volatile dispersion aid for promoting the aqueous dispersion of the acid-modified polyolefin resin, for example, an emulsifier, a compound having a protective colloid action, an acid-modified compound having a high acid value, a water-soluble polymer, etc. can do. In addition to the non-volatile dispersion aid, various additives and other additive resins which can make the physical properties more preferable by being added to the easily adhesive layer composition, more specifically, The non-volatile dispersion aid disclosed in the above-mentioned patent document (Japanese Patent Laid-Open No. 2014-240174) and various additives can be suitably used preferably.

(solvent)
An aqueous medium used as a main solvent in aqueous dispersion of the acid-modified polyolefin resin or the like in the dark aqueous primer coating solution used to form the dark easy adhesion layer 12 is water or a medium comprising a liquid containing water. Specifically, an aqueous medium is used as a main solvent, and the content of the aqueous medium with respect to 100 parts by mass of the solvent is more than 50 parts by mass and 100 parts by mass or less, preferably 70 parts by mass or more and 100 parts by mass or less is there.

  Further, in the aqueous dispersion containing the acid-modified polyolefin resin, an organic solvent having an SP value in a specific range as an auxiliary solvent is further added to the dark colored aqueous primer coating solution as long as the above-mentioned effects of the present invention are not inhibited. Can be included. Specifically, when the solvent of the easily adhesive layer composition contains an organic solvent as an auxiliary solvent, the content of the organic solvent with respect to 100 parts by mass of the solvent is more than 1 part by mass and 50 parts by mass Less than, preferably more than 5 parts by weight and less than 30 parts by weight.

<Manufacturing method of back surface protection sheet>
The back surface protection sheet 1 applies a dark aqueous primer coating solution, which is obtained by dissolving or dispersing the easily adhesive layer composition described in detail above in an aqueous medium, on the surface of the white resin base layer 11 and solidifies it. It can be manufactured by forming the dark easy adhesion layer 12.

[Formation of dark easy adhesion layer]
The dark-colored easy-adhesion layer 12 is formed on the surface of the white resin substrate layer 11 of the back surface protection sheet 1 by coating a dark-colored aqueous primer coating solution comprising the above-mentioned easy-adhesion layer composition by the following method. It can be carried out. Examples of the film forming method include gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, screen printing, brush coating method and the like. Further, as a heating device for promoting the drying of the solvent (aqueous medium) contained in the coating film, an ordinary hot air circulation type oven, an infrared heater or the like may be used.

  When the solvent is evaporated and removed from the coating film, the above-mentioned easy-adhesion layer composition and other additives added to the coating liquid remain on the surface of the white resin base layer 11 to form a film. This film becomes the dark color easy adhesion layer 12.

  The thickness of the easily dark-colored adhesive layer 12 is not particularly limited, and may be appropriately determined in accordance with the conditions to which the back surface protective sheet 1 is applied. The thickness of the dark-colored easy-adhesion layer 12 may be suitably adjusted according to, for example, the required adhesive strength, the desired optical properties, and the designability (color tone of black), etc., but usually 2.0 μm or more The thickness is preferably in the range of 15.0 μm or less, and more preferably 3.0 μm to 10 μm. When the thickness of the easily dark colored adhesive layer 12 is 2.0 μm or more, sufficient adhesion can be imparted to the back surface protective sheet 1. If the thickness of the easily dark-colored adhesive layer 12 is 15.0 μm or less, good blocking resistance can be imparted to the back surface protective sheet 1, and the manufacturing cost can also be suppressed. The application amount of the dark aqueous primer coating solution may be appropriately adjusted so that the thickness of the easy-to-adhere layer 12 falls within the above range as the application amount after drying. The solid content concentration of the dark aqueous primer coating solution, which is an aqueous dispersion, can be adjusted by the preparation composition at the time of preparation, and may be adjusted by diluting or concentrating the aqueous dispersion once prepared.

  The dark-colored easy-adhesion layer 12 formed on the white resin base material layer 11 exhibits excellent adhesiveness to the sealing material sheet 2 on the non-light-receiving surface side by the above-described manufacturing method. Further, by using an olefin resin and a dark primer coating solution containing an aqueous medium as a main solvent, it is possible to prevent the surface of the white resin base layer 11 from being damaged by the organic solvent during coating.

  EXAMPLES The present invention will be more specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

<Manufacture of back surface protection sheet>
The following dark aqueous primer coating solution is applied by gravure coating on the surface of the following white resin base material, and the coated coating solution is dried at a drying temperature of 110 ° C. for 2 minutes and then at 40 ° C. It aged for 5 days and formed the easily bonding layer, and was set as the back surface protection sheet of each Example and each comparative example. The coating amount of each coating liquid was 5.0 g / m ² in any of the examples and the comparative examples.

[Dark color aqueous primer coating solution]
As a material of the dark-colored aqueous primer coating liquid, an aqueous dispersion formed by stirring and mixing an easy-adhesion layer composition comprising the following respective materials and a solvent was used.
(Easy-to-adhere composition)
Acid-modified Poly-Ophine Resin: As a base resin, a prepared acid-modified Poly-Ophine resin powder material ("Bondyne (registered trademark)", manufactured by Tokyo Materials Co., Ltd., adjusting the polymerization conditions, each example and comparative example) It refine | purified so that it might become the particle size distribution of the range of Table 1, and after confirming the particle size of the powder material after refinement | purification by the above-mentioned method, it used for each Example and comparative example.
Organic dark pigment: benzimidazolone pigment (Pigment Brown 25, particle size 0.08 μm) and phthalocyanine pigment (amorphous phthalocyanine pigment blue (Pigment Blue 15, particle size 0.15 to 0.20 μm)) A mixture obtained by mixing the benzimidazolone-based pigment and the phthalocyanine-based pigment so as to have a content ratio of 52.5: 47.5 was used as an organic-based dark pigment used in Examples and Comparative Examples. The organic dark pigment average particle size was 0.11 μm. The particle size was measured by the method described above. About content of an organic type dark color pigment, it was mix | blended so that content in the resin component in an easily bonding layer composition might be 25.0 mass% also in any Example and comparative example.
Paraffin wax: “Paraffin wax aqueous dispersion (Nippon Seiki Co., Ltd., EMUSTAR-0135)”, the content of the resin component in the easily adhesive layer composition is 3.0% by mass in terms of solid content conversion ratio It mix | blended so that it might become each content as described in Table 1 in the range of 35.0 mass%.
Other resins: "Epocross WS700 manufactured by Nippon Shokubai Co., Ltd.". It added in the ratio of 5 mass parts with respect to 100 mass parts of base resin.
(solvent)
A mixed solution of distilled water (76 parts by mass), isopropanol (23 parts by mass), and triethylamine (1 parts by mass) was used as a solvent.

[White resin base layer]
The following white resin base sheet was used as a resin sheet for making it a white resin base layer of the back surface protection sheet of each example and each comparative example.
(White resin base sheet)
A titanium oxide added white PET film with a thickness of 188 μm (product name "Lumirror E20" manufactured by Toray Industries, Inc.)

<Test Example 1: (Adhesive evaluation)>
The test for evaluating the adhesiveness of the back surface protection sheet of this invention was done as follows.

[Production of adhesion evaluation sample]
About each Example and each comparative example, each back protection sheet, the vacuum laminator for manufacture of a solar cell module on the surface which coated the above-mentioned dark color water-based primer coating liquid on the following lamination conditions of the following sealing material sheet The laminate was used to make a sample for adhesive evaluation.
(Sealing material sheet)
1.5 parts by mass of a crosslinking agent (product name "Lupersol 101"), 100 parts by mass of EVA (a vinyl acetate content: 28%, product name "EVAFLEX / EV 250 grade", manufactured by Mitsui Dupont Polychemicals), crosslinking aid (TAIC) 0.5 parts by weight, 0.2 parts by weight of antioxidant (product name "NAUGARD-P"), 0.1 parts by weight of UV absorber (product name "Tinuvin 7709") and (product name "Cyasorb UV-531" ) A film obtained by forming a film having a thickness of 400 μm by a T-die method in which a film forming temperature is 90 ° C.).
(Lamination condition)
After pressure bonding was performed at 150 ° C. for 15 minutes at a pressure of 100 kPa with a vacuum laminator, lamination was performed under standard cure conditions in which the film was allowed to stand at 150 ° C. for 30 minutes in the high temperature layer.

[Adhesive test]
(Test method)
For each of the adhesion evaluation samples, the peel strength (N) was measured with 180 mm peel with a width of 15 mm for the adhesion initial value and the value after each durability test. For measurement, using a peeling test apparatus ("A & D Inc.", product name "TENSILON RTA-1150-H"), peeling conditions 50 mm / min at 23 ° C. with 180 degree peeling. The measurements were taken and the average of three measurements was taken.
(Evaluation criteria)
A: 50 N / 15 mm or more B: 26 N / 15 mm or more, less than 50 N / 15 mm C: 16 N / 15 mm or more, less than 26 N / 15 mm D: less than 16 N / 15 mm

<Test Example 2: (blocking resistance)>
The test for evaluating the blocking resistance of the back surface protection sheet of this invention was done as follows.

[Production of sample for evaluation of blocking resistance]
On the surface of the above-mentioned white resin base sheet ("Lumirror E20") used to form the white resin base layer of the back surface protection sheet of each example and each comparative example For the production of each example and each comparative example Each coating solution having the same composition as that used was applied by a bar coater, and the applied coating solution was dried at 110 ° C. for 2 minutes to form a dark easy adhesion layer on the surface of each substrate sheet. Then, the above-mentioned white resin base material ("Lumirror E20") was further overlaid on the surface of the dark-colored easy-adhesion layer immediately after drying, and this was used as a sample for evaluation of blocking resistance.

[Blocking resistance test]
(Test method)
Each of the samples for evaluation of blocking resistance was allowed to stand for 72 hours with a blocking tester (load 3 kg / cm ² , 40 ° C.). Then, the blocking resistance test was performed by the method of evaluating the blocking state by peeling off the overlapped part of the sample for evaluation removed from the tester and evaluated.
(Evaluation criteria)
A: The sheets are naturally separated without transfer of the dark easy adhesion layer B: No transfer of the dark easy adhesion layer, adhesion between the sheets is maintained but no response is obtained C: No transfer of the dark easy adhesion layer, the substrates Some adhesion resistance at peeling D: Transfer of dark easy adhesion layer, and / or adhesion at peeling between substrates

  From Table 1, the back surface protection sheet of the present invention provided with a dark easy adhesion layer excellent in design property optimizes the particle size ratio of the base resin to the pigment in the aqueous dispersion at the time of production of the easy adhesion layer composition. By combining the design properties of the dark color and the maintenance of the power generation efficiency by using near infrared rays, but also good adhesion to the sealing material sheet made of EVA resin and good blocking resistance. It was confirmed to be possessed.

DESCRIPTION OF SYMBOLS 1 back surface protection sheet 11 white resin base material layer 12 dark color easily bonding layer 2 sealing material sheet | seat of non-light-receiving surface side 3 sealing material sheet | seat of light-receiving surface side 4 transparent front substrate 5 solar cell element 6 metal frame 10 solar cell module

Claims (7)

A white resin base layer,
It is a manufacturing method of the back surface protection sheet for solar cell modules provided with the dark-colored easy-adhesion layer currently formed in the single side | surface of the said white resin base material layer,
Forming a dark easy-adhesion layer by applying a dark aqueous primer coating solution to the surface of the white resin base layer;
The dark aqueous primer coating solution is
An easily adhesive layer composition comprising an acid-modified polyolefin resin, an organic dark pigment transmitting near infrared rays having a wavelength of 750 nm or more and 1500 nm or less, and a wax,
An aqueous dispersion comprising a solvent having an aqueous medium as a main solvent,
The manufacturing method of a back surface protection sheet which makes the average particle diameter of the said acid-modified polyolefin resin in the said aqueous dispersion 1.0 to 2.5 times the average particle diameter of the said organic type dark color pigment. The organic dark pigment contains a brown pigment and a phthalocyanine pigment,
The brown pigment is a benzimidazolone pigment, 4-[(2,5-dichlorophenyl) azo] -3-hydroxy-N- (2,5-dimethoxyphenyl) -2-naphthalenecarboxamide, 1-[(4) C.-Nitrophenyl) azo] -2-naphthalenol, bis [3-hydroxy-4- (phenylazo) -2-naphthalenecarboxylic acid] copper salt, C.I. I. Pigment Brown 7, N, N'-bis (2,4-dinitrophenyl) -3,3'-dimethoxy-1,1'-biphenyl-4,4'-diamine, 3,4,9,10-perylenetetracarboxylic acid Diimide, Δ2,2 ′ (1H, 1′H) -binaphtho [2,1-b] thiophene-1,1′-dione and N, N ′-(10,15,16,17-tetrahydro-5,10 , 15, 17-tetraoxo-5H-dinaphtho [2,3-a: 2'3'-i] carbazole-4,9-diyl) bis (benzamide), at least one or more pigments selected from the group consisting of The manufacturing method of the back surface protection sheet of Claim 1.   The said wax is a paraffin wax, Content of this paraffin wax with respect to the resin component in an easily bonding layer composition is 10 mass% or more and 38 mass% or less in solid content conversion ratio. Production method of back surface protection sheet.   The method for producing a back surface protective sheet according to any one of claims 1 to 3, wherein the solvent contains an organic solvent as an auxiliary solvent in a content range of less than 50 parts by mass per 100 parts by mass of the solvent.   The acid-modified polyolefin resin is ethylene-acrylic acid ester-maleic anhydride terpolymer or ethylene-methacrylic acid ester-maleic anhydride terpolymer, or a mixed resin thereof. The manufacturing method of the back surface protection sheet in any one of claim | item 1 -4.   The manufacturing method of the back surface protection sheet in any one of Claim 1 to 5 whose base resin of the said white resin base material layer is polyester-type resin.   Bonding the back surface protective sheet produced by the production method according to any one of claims 1 to 6 to a sealant sheet having an olefin resin as a base resin via the dark color easy adhesion layer, Method of manufacturing a solar cell module

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