WO2017187643A1 - Reflective sheet, and solar cell module and led lighting device each using same - Google Patents

Abstract

The purpose of the present invention is to provide: a reflective sheet which is capable of highly reflecting light in a wide wavelength range from ultraviolet light to near infrared light without spending much cost and working time, while achieving a heat absorption effect; and a solar cell module and an LED lighting device, each of which uses this reflective sheet. In order to achieve this purpose, a reflective sheet according to the present invention comprises a base, a white layer formed on the base, and a resin layer provided on the white layer, and is characterized in that the white layer is formed using a white resin composition that contains a white pigment and a thermoplastic resin that is obtained by copolymerizing monomers including an aromatic dicarboxylic acid, a compound represented by general formula (1) and an aliphatic diol having 5-7 carbon atoms. AA General formula (1)

Description

Reflective sheet, and solar cell module and LED lighting using the same

The present invention relates to a reflective sheet, and a solar cell module and LED lighting using the same.

The present invention is, for example, an agricultural vinyl film, a film for protecting a surface of an outer layer signboard, a barrier film for preventing discoloration, fading, light degradation, etc. The present invention relates to a film, a solar cell backsheet, a reflective sheet used for LED lighting, and the like, and a solar cell module and LED lighting using the same.

◎ Ultraviolet rays with a short wavelength in sunlight have a harmful effect on human bodies and animals and plants compared to visible rays and infrared rays. For this reason, for example, window glass and agricultural vinyl for houses are required to have an ultraviolet shielding or reflecting effect.

In recent years, next-generation energy infrastructure such as solar cells, which replace energy infrastructure such as fossil fuel and electronic power, has attracted attention from the viewpoint of prevention of environmental pollution and safety. Examples of a general solar battery include a silicon system using silicon as a material, a compound system that forms a compound semiconductor using copper, indium, selenium, potassium, and the like, and an organic system that uses an organic compound for a photoelectric conversion layer. . These solar cells generate power mainly by converting visible light into energy.

In such a conventional solar cell, improvement of the energy conversion rate of visible light is one of the technical problems. Therefore, many reflection sheets (solar cell backsheets) that reflect a large amount of sunlight, particularly visible light, have been developed.

On the other hand, as described above, an improvement in the energy conversion rate of sunlight is required, and the development of solar cells capable of converting energy of not only visible light but also ultraviolet rays and near infrared rays is progressing. A reflection sheet capable of efficiently reflecting sunlight at a wavelength is desired.

Furthermore, even in LED lighting that has become widespread due to the recent increase in demand for energy saving and the like, there is a strong demand for a reflection sheet that can highly reflect light of a wide range of wavelengths emitted from an LED as a light source.

Examples of the reflection sheet for improving the reflectance of visible light and near infrared light include those provided with an aluminum film vapor deposition layer or surface roughness on the surface of the sheet. However, these manufactures require steps such as aluminum deposition and surface treatment, leading to a decrease in production efficiency and an increase in the cost of the reflective sheet.

In addition, as a conventional reflective sheet for ultraviolet rays, a film containing an ultraviolet reflector such as titanium oxide, sodium oxide or zinc oxide, or an ultraviolet absorber such as oxybenzone or silosoma, or a resin composition containing these is used. UV rays were blocked, absorbed or reflected by being applied to a film. However, a film containing an ultraviolet absorber is deteriorated in weather resistance due to deterioration of a resin around the ultraviolet absorber, and a film containing an ultraviolet reflector such as titanium oxide simply has no ultraviolet reflector. Although the incident ultraviolet rays are irregularly reflected, the amount of ultraviolet absorption in the film or the reflective sheet increases due to repeated irregular reflections between these ultraviolet reflectors, leading to deterioration of the film and the reflective sheet. there were.

As a technique for solving the above-mentioned problem of ultraviolet rays, a material having a plurality of different refractive indexes on a polymer layer containing a light stabilizer provided on a substrate (the refractive index film layer is an oxide containing Si or Al). High refractive index film layer is composed of oxide, nitride oxide or nitride containing Zn, Ti, Sn, In, Nb, Si, Ta or Al). And a method of providing an ultraviolet reflective layer (see Patent Document 1). However, this has a problem that the working efficiency is poor because the low refractive index layer and the high refractive index layer are alternately laminated, and the cost increases because a film layer made of an oxide or the like is formed.

In addition, when using a reflective sheet as a back sheet for solar cells, the wavelength region where high reflection is desired differs slightly depending on the type of solar cell used. Therefore, a back sheet with different performance is developed and prepared depending on the type of solar cell. There was also a problem that it was difficult to apply and use each other.

International Publication WO2010 / 024193

The present invention has been made in order to solve the above-described problems, and can reflect light in a wide range of wavelengths from ultraviolet rays to near infrared rays without cost and work time, and can obtain a heat absorption effect. It is an object of the present invention to provide a sheet and a solar cell module and LED lighting using the sheet.

In order to achieve the above object, the present invention has the following configuration.

(1) The reflective sheet of the present invention is a reflective sheet including a base material, a white layer formed on the base material, and a resin layer provided on the white layer. Resin composition comprising a thermoplastic resin and a white pigment obtained by copolymerizing a monomer comprising an aromatic dicarboxylic acid, a compound represented by the following general formula (1) and an aliphatic diol having 5 to 7 carbon atoms It is characterized by being formed using an object.

(2) In the configuration described in (1) above, the white pigment is titanium oxide, and the titanium oxide includes titanium oxide (A) having an average particle diameter of 0.1 μm to 0.3 μm and an average particle It includes titanium oxide (B) having a diameter of 0.3 μm to 0.5 μm.

(3) In the configuration described in the above (1) or (2), the compounding amount of the titanium oxide (A) and the titanium oxide (B) is the titanium oxide ( A) is 17 wt% to 20 wt%, and the titanium oxide (B) is 7 wt% to 10 wt%.

(4) In the configuration according to any one of (1) to (3), the white layer further includes at least one of aluminum hydroxide, zinc oxide, calcium carbonate, talc, and barium. Features.

(5) In the configuration described in any one of (1) to (4) above, at least one of the base material and the resin layer includes a white pigment.

(6) The solar cell module of the present invention is characterized by using the reflection sheet described in any one of (1) to (5) above.

(7) The LED illumination of the present invention is characterized by using the reflection sheet described in any one of (1) to (5) above.

The reflection sheet of the present invention can highly reflect light in a wide range of wavelengths from ultraviolet rays to near infrared rays without cost and work time, and can also obtain a heat absorption effect. Therefore, when this is used for a solar cell module, it is possible to obtain good power generation efficiency regardless of the type of solar cell and to suppress a temperature rise due to light reflection, not only the weather resistance of the reflective sheet itself, The weather resistance of the solar cell can also be improved. In addition, the LED illumination using the reflection sheet of the present invention can highly reflect light of a wide wavelength emitted from the light source, and can suppress the temperature rise due to the light reflection, thereby further extending the product life of the LED illumination. it can.

The schematic sectional drawing of the reflective sheet which concerns on one Embodiment of this invention. The schematic sectional drawing of the solar cell module using the reflective sheet which concerns on one Embodiment of this invention. The graph which measured the reflectance of 300 nm at the time of irradiating light using the ultraviolet visible spectrophotometer about the reflective sheet which concerns on the Example and comparative example of this invention.

Hereinafter, an embodiment of the present invention will be described in detail.

The reflective sheet of this embodiment includes a base material, a white layer formed on the base material, and a resin layer provided on the white layer.

1. Base material As a base material used for the reflective sheet of this embodiment, if it can hold | maintain the said white layer and the said resin layer, such as glass, a resin base material, and a resin film, it can be used without a restriction | limiting. Among these, a resin substrate or a resin film is particularly preferably used.

As the resin substrate or resin film, a resin substrate or resin film made of polyester is particularly preferably used, and among them, a resin substrate or resin film made of polyethylene naphthalate or polyethylene terephthalate is particularly preferably used.

In this embodiment, a white base material in which a white pigment is blended can be used as the base material. By using such a white base material, the white base material and the white pigment contained in the white layer exhibit a synergistic effect, and a reflective sheet using the white base material can highly reflect visible light particularly from ultraviolet rays.

As such a white pigment, titanium oxide, zinc oxide, lithopone and the like can be used. Of these, titanium oxide is particularly preferably used as the white pigment.

As the titanium oxide, both rutile titanium oxide and anatase titanium oxide can be used. In addition, titanium oxide that has been surface-treated with aluminum hydroxide and silicon, or aluminum hydroxide and zirconia can be suitably used.

Examples of the rutile type titanium oxide include Taipei (registered trademark) R-550, Taipei R-630, Taipei R-670, Taipei R-680, Taipei R-780, Taipei R-820, Taipei R-830, Taipei R- 850, Type R-930, Type CR-50, Type CR-57, Type CR-58, Type CR-60, Type CR-63, Type CR-67, Type CR-80, Type CR-85, Type CR-85 90, Taipei CR-93, Taipei CR-95, Taipei CR-97, Taipei UT771 (manufactured by Ishihara Sangyo Co., Ltd.), Thailand Pure (registered trademark) R-100, Thailand Pure R-101, Thailand Pure R-102, Thailand Pure R-103, Taipyu R-104, Taipure R-105, Taipure R-108, Taipure R-706, Taipure R-900, Taipure R-902, Taipure R-960, Taipure R-931 (above, manufactured by DuPont), R- 21, R-25, R-32, R-42, R-44, R-7E, R-5N, R-61N, R-62N, R-45M, R-49S, GTR-100, GTR-300, D-918, TCR-29, TCR-52, FTR-700 (above, manufactured by Sakai Chemical Industry Co., Ltd.) and the like.

As anatase type titanium oxide, for example, TITON A-110, TITON A-190, TITON A-197, TITON TCA-123E, TITON SA-1, TITON SA-1L (above, manufactured by Sakai Chemical Industry Co., Ltd.) TA-100, TA-200, TA-300, TA-400, TA-500, TP-2 (above, manufactured by Fuji Titanium Industry Co., Ltd.), TITANIX (registered trademark) JA-1, TITANIX JA-3, TITANIX JA-4, TITANIX JA-5, TITANIX JA-C, TITANIX JR-603 (above, manufactured by Teika), KA-10, KA-15, KA-20, KA-30 (above, Titanium Industry ( Co., Ltd.), Taipei A-100, Taipei A-220, Taipei W-1 (Above, Ishihara Sangyo Co., Ltd.).

When the white pigment is blended in the base material, the average particle size is preferably 0.25 μm or more, more preferably 0.28 μm or more, and particularly preferably 0.3 μm or more. If the average particle size is less than 0.25 μm, the wavelength of light that can be efficiently scattered shifts to the lower wavelength side, and thus the reflectance in the near-infrared light region may decrease. On the other hand, if the average particle size exceeds 10 μm, depending on the particle size distribution, coarse particles may be contained, so that defects such as pinholes may occur in the film.

When a white pigment is blended in the base material, the blending amount is 0.5% by weight or more, preferably 3% to 80% by weight, more preferably 20% to 80% by weight. If the amount of the white pigment exceeds 80% by weight, the substrate becomes brittle, and practical mechanical strength may not be obtained, which is not preferable.

The thickness of the substrate is preferably 50 μm to 200 μm. In addition, you may affix a resin film on the surface on the opposite side to the surface which forms the said white layer in the said base material. As such a resin film, for example, a film made of polyethylene terephthalate or polyethylene naphthalate is preferably used.
Furthermore, you may mix | blend the said white pigment with such a resin film. Examples of the polyester film containing a white pigment include Toraybo Co., Ltd. Krisper (registered trademark) K1212, SHINEBEAM (registered trademark) White, Teijin DuPont Films Co., Ltd. Teijin (registered trademark) Tetron (registered trademark) film VW. Etc.

2. White Layer The white layer according to this embodiment is obtained by copolymerizing a monomer containing an aromatic dicarboxylic acid, a compound represented by the following general formula (1), and an aliphatic diol having 5 to 7 carbon atoms. It is formed using a white resin composition containing a thermoplastic resin and a white pigment.

(1) Thermoplastic resin The thermoplastic resin is obtained by copolymerizing a monomer containing an aromatic dicarboxylic acid, a compound represented by the following general formula (1), and an aliphatic diol having 5 to 7 carbon atoms. It is preferred that

Examples of the aromatic dicarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 4,4-stilbene dicarboxylic acid, 4,4-biphenyldicarboxylic acid, orthophthalic acid, and naphthalenedicarboxylic acid. Of these, terephthalic acid and isophthalic acid are preferably used in combination.

Examples of the compound represented by the general formula (1) include isosorbide.

Further, as the aliphatic diol having 5 to 7 carbon atoms, both linear and branched ones can be used. For example, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1, Examples include 5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and the like. *

A method for copolymerizing the monomer containing the aromatic dicarboxylic acid, the compound represented by the general formula (1), and the aliphatic diol having 5 to 7 carbon atoms is not particularly limited. Can be used. The copolymerization conditions such as the copolymerization ratio of each component and the temperature at the time of copolymerization can be appropriately changed depending on the glass transition temperature, viscosity and the like required for the obtained thermoplastic resin. Further, for the monomer components other than the aromatic dicarboxylic acid, the compound represented by the general formula (1), and the aliphatic diol having 5 to 7 carbon atoms, a glass transition temperature required for the obtained thermoplastic resin, As such a thermoplastic resin that can be appropriately changed depending on the viscosity and the like, for example, Byron (registered trademark) (manufactured by Toyobo Co., Ltd.) can be used, among which Byron (registered trademark) TU-02HA is particularly preferable. Used.

The blending amount of the thermoplastic resin is preferably 50% by weight to 80% by weight with respect to the total amount of the white resin composition.

The white resin composition may be combined with an isocyanate compound that reacts and crosslinks with a hydroxyl group contained therein for the purpose of curing the thermoplastic resin. By blending the isocyanate compound, moisture resistance and heat resistance can be imparted to the white layer to be formed, and adhesion between the substrate and the resin layer can be further improved. Therefore, the isocyanate compound preferably has a plurality of isocyanate groups in one molecule.

Examples of such isocyanate compounds include diisocyanates such as trimethylene diisocyanate, hexamethylene diisocyanate, methylene bis (4,1-phenylene) = diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, and xylylene diisocyanate. A trimethylolpropane adduct of diisocyanate; an isocyanurate which is a trimer of diisocyanate; a burette conjugate of diisocyanate, and a polymeric diisocyanate.
The blending amount of such an isocyanate compound is preferably 0.03% by weight to 10% by weight with respect to the total amount of the thermoplastic resin.

(2) White pigment As the white pigment, titanium oxide, zinc oxide, lithopone and the like can be used. Of these, titanium oxide is particularly preferably used as the white pigment.

As the titanium oxide, the same titanium oxide blended in the base material can be used, but titanium oxide (A) having an average particle diameter of 0.1 μm to 0.3 μm and an average particle diameter of 0.3 μm. To 0.5 μm of titanium oxide (B).
As the titanium oxide, titanium oxides (A) and (B) are preferably coated with aluminum hydroxide and further surface-treated with silicon or zirconia. By using such titanium oxide, ultraviolet rays and visible rays can be efficiently reflected. Examples of such titanium oxide include Cr-Super 70 manufactured by Ishihara Sangyo Co., Ltd.

Thus, when forming a white layer using a white resin composition containing titanium oxides having different average particle diameters, titanium oxides having different particle diameters are formed at the interfaces between the formed white layer and the base material and the resin layer. Will exist. As a result, the same effect as that obtained by subjecting the base material and the resin layer to surface treatment can be obtained. By changing the reflection direction, light having a wide wavelength (from ultraviolet to near infrared) can be diffused. Thus, a high reflectance can be obtained by returning to the solar battery cell side.
In addition, since the white layer contains titanium oxide (B) having an average particle size of 0.3 μm to 0.5 μm and a large particle size, the heat absorption effect of the white layer can also be achieved.

The compounding amount of the titanium oxide (A) and the titanium oxide (B) is 17% to 20% by weight of the titanium oxide (A) and 7% of the titanium oxide (B) with respect to the total amount of the white resin composition. It is preferably from 10% to 10% by weight. By adjusting the compounding amounts of the titanium oxide (A) and the titanium oxide (B) in this way, the high reflection and heat absorption effect in a wide wavelength range of the reflection sheet can be further improved.
The white resin composition of the present embodiment may contain titanium oxide other than the titanium oxide (A) and the titanium oxide (B), and the preferred range of the total amount of titanium oxide is the white resin. It is 24 wt% to 70 wt%, more preferably 24 wt% to 50 wt%, still more preferably 24 wt% to 30 wt%, based on the total amount of the composition.

(3) Others The white resin composition may contain, for example, other resins and at least one of aluminum hydroxide, zinc oxide, calcium carbonate, talc and barium, an organic solvent, an additive, and the like.

Examples of the other resins include thermoplastic resins other than the thermoplastic resins (other thermoplastic resins), photocurable resins, and thermosetting resins.

Other thermoplastic resins include, for example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, and liquid crystal polyester; polyolefins such as polyethylene, polypropylene, polybutene 1, and polybutylene; styrene resins, polyoxymethylene , Polyamide, polycarbonate, polymethyl methacrylate, polyvinyl chloride, polyphenylene ether, polyphenylene sulfide, polyimide, polyurethane, polyamideimide, polyetherimide, polysulfone, polyethersulfone, polyketone, polyetherketone, polyetheretherketone, polyetherketone Ketone, polyarylate, polyethernitrile, phenolic resin (example If phenol novolak), a phenoxy resin, and can be used a copolymer thereof, a modified product. These may be used alone or in combination as required.

In the present embodiment, other thermoplastic resins having a hydroxyl group or having a hydroxyl group added are preferably used. As such other thermoplastic resins, any oligomer or polymer having a hydroxyl group can be used without any particular limitation. For example, polyamides, polyesters, vinyl polymers having a hydroxyl group, copolymers of various acrylates and methacrylates, phenol resins, cresol resins, and the like can be given.

Examples of the polyester include Nipponran (registered trademark) 800, 1100, 121, 1004, 136, 141, 4070 (manufactured by Nippon Polyurethane Industry Co., Ltd.).

When the other thermoplastic resin is blended with the white resin composition, an isocyanate compound that reacts with and crosslinks with a hydroxyl group contained in the other thermoplastic resin can be blended as appropriate. The blending amount of the isocyanate compound that reacts with the other thermoplastic resin is preferably 0.03% by weight to 10% by weight with respect to the total amount of the other thermoplastic resin.
As such an isocyanate compound, the same thing as what is mix | blended together with the said thermoplastic resin can be used.

Next, as the photocurable resin, known resins can be used as long as they are resin compositions that are cured by irradiation with active energy rays, and examples thereof include photopolymerizable oligomers and photopolymerizable vinyl monomers. .

When mix | blending a photocurable resin with the said white resin composition, it is preferable to mix | blend a photoinitiator together. Examples of such photopolymerization initiators include acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, diethoxyacetophenone, 2,2-diethoxy. Acetophenones such as -2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one; methyl Anthoraquinones such as anthraquinone, 2-ethylanthoraquinone, 2-tert-butylanthoraquinone, 1-chloroanthoraquinone, 2-amylanthoraquinone; thioxanthone, 2,4-diethylthioxanthone, 2 -Chlorothioxanthone, 2,4-dichloro Thioxanthones such as thioxanthone, 2-methylthioxanthone, and 2,4-diisopropylthioxanthone; Ketals such as acetophenone dimethyl ketal and benzyldimethyl ketal; Benzophenones such as benzophenone and 4,4-bismethylaminobenzophenone Etc. These can be used alone or in combination.
When using the said photoinitiator, the compounding quantity is not specifically limited, It can change suitably with the kind and quantity of photocurable resin to be used.

Next, as the thermosetting resin, for example, epoxy resin, phenol resin, unsaturated imide resin, cyanate resin, isocyanate resin, benzoxazine resin, oxetane resin, amino resin, unsaturated polyester resin, allyl resin, dicyclopentadiene Examples thereof include resins, silicone resins, triazine resins, melamine resins, and urea resins. Among these, an epoxy resin is preferably used.

The epoxy resin includes a compound having one or more epoxy groups. Of these, compounds having two or more epoxy groups are preferably used. Examples of such epoxy resins include monoepoxy compounds such as butyl glycidyl ether, phenyl glycidyl ether, and glycidyl (meth) acrylate, bisphenol A type epoxy resins, bisphenol S type epoxy resins, bisphenol F type epoxy resins, and phenol novolac type epoxies. Resin, cresol novolac epoxy resin, alicyclic epoxy resin, trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether, biphenyl-4,4′-diglycidyl ether, 1,6-hexanediol diglycidyl Ether, diglycidyl ether of ethylene glycol or propylene glycol, sorbitol polyglycidyl ether, tris (2,3-epoxypropyl) isocyanurate, Compounds having two or more epoxy groups in one molecule, such as Li glycidyl tris (2-hydroxyethyl) isocyanurate.

When mix | blending the said thermosetting resin with the said white resin composition, in order to accelerate | stimulate the thermosetting of the said thermosetting resin, it is preferable to mix | blend a curing catalyst. Examples of such a curing catalyst include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1 Imidazole derivatives such as-(2-cyanoethyl) -2-ethyl-4-methylimidazole; dicyandiamide, benzyldimethylamine, 4- (dimethylamino) -N, N-dimethylbenzylamine, 4-methoxy-N, N-dimethyl Amine compounds such as benzylamine, 4-methyl-N, N-dimethylbenzylamine, hydrazine compounds such as adipic acid dihydrazide, sebacic acid dihydrazide; phosphorus compounds such as triphenylphosphine; metal soaps such as cobalt naphthenate and copper naphthenate And the like.
Guanamine, acetoguanamine, benzoguanamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-4,6-diamino-S-triazine, 2-vinyl which also function as an adhesion-imparting agent S-triazine derivatives such as -4,6-diamino-S-triazine / isocyanuric acid adduct and 2,4-diamino-6-methacryloyloxyethyl-S-triazine / isocyanuric acid adduct can also be added.
These may be used alone or in combination as required. The amount of such a curing catalyst is 0.05 to 10% by weight, preferably 0.1 to 3% by weight, based on 100% by weight of the thermosetting resin.

When the thermoplastic resin and another resin are used in combination, the total amount is preferably 50% by weight to 80% by weight with respect to the total amount of the white resin composition. *

The white resin composition can contain at least one of aluminum hydroxide, zinc oxide, calcium carbonate, talc and barium, and these can be used alone or in combination. Of these, aluminum hydroxide is particularly preferably used. By mix | blending these, the ultraviolet reflective effect of the white layer and reflection sheet to be formed can be improved.
In particular, by using titanium oxide and aluminum hydroxide as a white pigment in combination, both ultraviolet light and visible light can be efficiently reflected.

As the aluminum hydroxide, known ones can be used. For example, C-3005, C-301, CL-303 (manufactured by Sumitomo Chemical Co., Ltd.), Heidilite (registered trademark) H-21, H- 31, H-32, H-42, H-42M, H-43M (above, manufactured by Showa Denko KK).
The blending amount of the aluminum hydroxide is preferably 0.5% by weight to 5% by weight with respect to the total amount of the white resin composition.
Moreover, about zinc oxide, a calcium carbonate, a talc, and barium, all can use a well-known thing. These total blending amounts are preferably 0.5% by weight to 5% by weight with respect to the total amount of the white resin composition.

The white resin composition can be blended with an organic solvent for the purpose of preparing it and adjusting the viscosity.
Examples of such organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, Glycol ethers such as propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, tripropylene glycol monomethyl ether; ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol Acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether Acetate, hexamethylene diisocyanate diethylene glycol monoethyl ether acetate, esters such as propylene carbonate; octane, aliphatic hydrocarbons decane; petroleum ether, petroleum naphtha, and petroleum solvents such as solvent naphtha. These can be used alone or in combination.
It is preferable that the compounding quantity of these organic solvents is 50 weight% or less with respect to the said white resin composition whole quantity.

As the additive, for example, a polyurethane-based adhesive can be blended in order to increase the adhesion between the base material of the white layer and the resin layer. Examples of such polyurethane-based adhesives include Seika Bond (registered trademark) E-263, Seika Bond C-26 (manufactured by Dainichi Seika Kogyo Co., Ltd.), Takelac (registered trademark) A3210, Takenate (registered trademark). A3072 etc. (above, Mitsui Chemicals Polyurethane Co., Ltd. product) is mentioned. The blending ratio of such a polyurethane adhesive is preferably 10% by weight or less based on the total amount of the white resin composition.

Further, as the additive, if necessary, thickeners such as finely divided silica, organic bentonite, montmorillonite, antifoaming agents such as silicones and polymers, leveling agents, silanes such as imidazole, thiazole and triazole A coupling agent etc. can be mix | blended with the said white resin composition. It is preferable that these compounding quantities are 10 weight% or less with respect to the said white resin composition whole quantity.

The white layer is formed, for example, by applying the white resin composition to the substrate and curing it. The thickness of the formed white layer is preferably 17 μm to 30 μm. By setting the thickness of the white layer in this range, the reflectance of visible light of the reflection sheet can be further increased.

3. Resin layer The resin layer is preferably a polyester film or a coating layer of a resin composition containing a polyester resin.

Examples of the polyester film used for the resin layer include commonly used polyesters such as polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, or polyethylene naphthalate. Among these, polyethylene terephthalate and polyethylene naphthalate are particularly preferably used.

Further, when the resin layer is composed of a coating layer of a resin composition containing a polyester resin, for example, a resin composition containing polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate or polyethylene naphthalate is coated on the white layer. The resin composition containing an unsaturated polyester resin is applied on the white layer and thermally cured.

A white pigment can be blended in the resin layer. As such a white pigment, the same pigments as those incorporated in the substrate can be used, and titanium oxide is particularly preferably used.
When a white pigment is blended in the resin layer, the blending amount is 0.5 wt% or more, preferably 3 wt% to 80 wt%, more preferably 20 wt% to 80 wt%. If the amount of the white pigment exceeds 80% by weight, the resin layer becomes brittle and a practical mechanical strength may not be obtained.

In particular, when a polyester film is used as the resin layer and titanium oxide is added as a white pigment to the polyester film, the polyester film is biaxially stretched by applying heat. Since it is different from the white layer, the reflection sheet of this embodiment having such a configuration can realize high reflection of visible light in particular.
When a polyester film containing a white pigment is used as the resin layer, for example, Teijin (registered trademark) Tetron (registered trademark) film U2 manufactured by Teijin DuPont Films, Teijin (registered trademark) Tetron (registered trademark) film VW, Toyobo SHINEBEAM (registered trademark) White manufactured by Co., Ltd. can be used.

The resin layer may contain additives other than the polyester resin, and examples of such additives include hydrolysis resistance modifiers, solid phase polymerization accelerators, antioxidants, flame retardants, and the like. It is done.

The thickness of the resin layer is preferably 17 μm to 30 μm.

Further, the reflective sheet of the present embodiment has an adhesive between the base material and the white layer, between the white layer and the resin layer, or on the surface of the resin layer within a range that does not affect the light reflection. Can be applied to form an adhesive layer. Thereby, the adhesive force of the said base material and the said white layer or the said white layer and the said resin layer can be improved. Moreover, when using the reflective sheet which concerns on this embodiment as a solar cell backsheet, by forming such an adhesive layer on the surface of the resin layer, the reflective sheet and EVA as a sealing material for the solar cell module Can be improved.

As such an adhesive, a polyurethane-based adhesive or an isocyanate-based adhesive is preferably used.
Examples of the polyurethane adhesive include Seika Bond (registered trademark) E-263, Seika Bond C-26 (above, manufactured by Dainichi Seika Kogyo Co., Ltd.), Takelac (registered trademark) A3210, Takenate (registered trademark) A3072 and the like. (Mitsui Chemicals Polyurethane Co., Ltd.).
Moreover, as said isocyanate adhesive, the commercial item of Coronate (trademark) L etc. (made by Nippon Polyurethane Industry Co., Ltd.) can be used, for example.
These polyurethane-based adhesives and isocyanate-based adhesives can be blended with reaction catalysts and other additives within a range that does not adversely affect adhesiveness and pot life.

The thickness of the reflective sheet according to the present embodiment can be freely adjusted according to its use, but is particularly preferably 195 μm to 350 μm.

The reflective sheet according to the present embodiment is manufactured by, for example, the following method.

In this embodiment, a film made of polyethylene naphthalate is used as the substrate.
When a white pigment is blended in the polyethylene naphthalate film, the method is not particularly limited, and a conventional method can be appropriately employed. For example, the method of adding the said white pigment in the arbitrary steps which manufacture a polyethylene naphthalate component is mentioned. Preferably, the polycondensation reaction may be advanced by adding the white pigment at the esterification stage or after completion of the transesterification reaction. Alternatively, a white pigment slurry dispersed in ethylene glycol or water and a polyester raw material may be blended using a kneading extruder with a vent. Moreover, the method of blending the dried white pigment and the polyester raw material using a kneading extruder may be used.

First, polyethylene naphthalate is dissolved, and this is cooled and solidified using a casting drum to obtain an unstretched film. The unstretched film is stretched at a glass transition temperature of Tg 121 ° C. to (Tg + 60) ° C. once or twice or more in the longitudinal direction so that the total magnification becomes 3 to 6 times. Further, this is stretched at Tg 121 ° C. to (Tg + 60) ° C. so that the magnification is 3 to 6 times in the width direction, and a polyethylene naphthalate film having a thickness of 250 μm, for example, is produced. If necessary, the film may be heat-treated at 180 to 230 ° C. for 1 to 60 seconds.

Next, a white resin composition adjusted to a viscosity suitable for coating with an organic solvent is applied to the surface of the polyethylene naphthalate film on which the white layer is to be formed so that the film thickness is 17 μm to 20 μm. The white resin composition preferably contains aluminum hydroxide in addition to titanium oxide (A) and titanium oxide (B) having different particle diameters.
Thereafter, the white resin composition applied to the polyethylene naphthalate film is dried at a temperature of 70 ° C. to 90 ° C., thereby volatilizing the organic solvent contained therein to form a coating film. As a coating method of the white resin composition, a screen printing method, a curtain coating method, a spray coating method, a roll coating method, or the like can be appropriately used. In addition, a hot air circulation drying furnace, an IR furnace, a hot plate, a convection oven or the like is used for volatile drying of the organic solvent. Then, the reflective sheet in which the white layer was formed on the said base material can be created by maintaining the bonding roll temperature at 80 to 100 degreeC, and crimping | bonding the said base material.

In addition, you may form the said coating film using the dry film which consists of the said white resin composition instead of apply | coating the said white resin composition to the said polyethylene naphthalate film as mentioned above.
Such a dry film is formed by applying the white resin composition to a carrier film made of, for example, polyethylene terephthalate and drying to form a white resin layer, and a cover film such as a peelable polyethylene film or polypropylene film is formed thereon. Laminated. Specifically, the white resin layer is obtained by applying the white resin composition to a carrier film with a blade coater, a lip coater, a comma coater, a film coater, a Mayer bar coater, a micro gravure coater, and the like. It is formed by drying.

Then, the cover film of the dry film is peeled off, the white resin layer and the polyethylene naphthalate film are overlaid, and these are laminated together using a laminator or the like, thereby coating the white film layer on the polyethylene naphthalate film. Is formed. And if the said coating film is heated similarly to the above, a white layer can be formed on the said polyethylene naphthalate film.

Next, a resin layer is formed on the white layer. As the resin layer, for example, a polyethylene naphthalate film (hereinafter referred to as “resin film” to be distinguished from the base material) can be used. As a method for producing such a resin film, for example, dissolved polyethylene naphthalate is cooled and solidified using a casting drum to obtain an unstretched film. The unstretched film is stretched at a glass transition temperature of Tg 121 ° C. to (Tg + 60) ° C. once or twice or more in the longitudinal direction so that the total magnification becomes 3 to 6 times. Further, this is stretched at Tg 121 ° C. to (Tg + 60) ° C. so that the magnification is 3 to 6 times in the width direction to produce a polyethylene naphthalate film which is a resin film having a thickness of 50 μm to 75 μm. If necessary, the film may be heat-treated at 180 to 230 ° C. for 1 to 60 seconds.

And the reflective sheet which concerns on this embodiment is produced by adhere | attaching or crimping | bonding the said resin film on the surface of the said white layer. As the said adhesion method, it carries out by carrying out the thermocompression bonding to the surface of the said white layer using the roll group etc. which heated the said resin film.

As another embodiment, a reflective sheet can be produced by forming a white layer on the surface of the resin film and thermocompression bonding the polyethylene naphthalate film on the surface of the white layer.

In addition to these embodiments, a reflective sheet can be produced by using an extrusion sand laminator method in which the white resin composition is extruded and laminated between the polyethylene naphthalate film and the resin film.

Next, the reflective sheet of this embodiment is demonstrated easily using FIG.
The reflective sheet 10 of this embodiment includes a base material 1 made of a polyester film, a white layer 2, and a resin layer 3.

In addition, the reflective sheet which mix | blended titanium oxide as a white pigment in the said base material and the said resin layer, and mix | blended titanium oxide and aluminum hydroxide in the said white layer can implement | achieve the light reflection in a much wider wavelength. .

Further, a solar cell module in the case where such a reflection sheet is used as a back sheet of a crystalline silicon solar cell will be described with reference to FIG.

The solar cell module 100 of this embodiment includes a reflective sheet 10 (solar cell backsheet), an encapsulant 20 made of EVA, solar cells 30, and a surface protective material substrate 40 made of glass. Sunlight incident from the surface protective substrate 40 is absorbed by the solar battery cell 30 and converted into energy. Sunlight that could not be absorbed by the solar battery cell 30 passes through the sealing material 20 and enters the reflection sheet 10. And the reflective sheet 10 can reflect the incident sunlight efficiently in a wide wavelength from ultraviolet rays to near infrared rays, and can return this to the solar battery cell 30.

The reflection sheet of this embodiment having such a configuration can highly reflect light having a wide range of wavelengths from ultraviolet rays to near infrared rays, and can also exhibit a heat absorption effect. Therefore, when the said reflective sheet is used as a solar cell backsheet, for example, it can improve the power generation efficiency of a solar cell module by reflecting incident sunlight efficiently in a wide wavelength from ultraviolet rays to near infrared rays.

That is, near-infrared light is absorbed by the molecules of the material to which it is irradiated, and the state of quantized vibration or rotation changes. In addition, since ultraviolet rays deteriorate the material irradiated by ultraviolet rays, in the case of a reflective sheet that does not reflect ultraviolet rays and near infrared rays, or reflects only a small amount of these, the reflection sheet itself and the vicinity thereof are caused by vibration of molecules due to near infrared rays and deterioration by ultraviolet rays. There is a risk that the substance in the water is easily hydrolyzed.
In particular, when a reflective sheet is used as a solar cell backsheet, EVA laminated on the reflective sheet is likely to be hydrolyzed. When EVA is hydrolyzed, acetic acid and moisture are produced. The acetic acid and moisture generate sodium ions by contact with the surface protective material substrate made of glass used in the module for solar cell. The generated sodium ions diffuse into the EVA and enter the cell surface and inside, causing the power generation efficiency of the solar cell to be hindered. In particular, since a high voltage is applied to the solar cell module during power generation, generation of sodium ions is promoted.

However, as described above, the reflective sheet of the present embodiment is highly weatherable and can reflect light in a wide range of wavelengths from ultraviolet to near infrared by forming the white layer from the white resin composition having the above-described configuration. . In particular, the white layer highly reflects ultraviolet rays and can also reflect near infrared rays by using titanium oxides (A) and (B) having different particle diameters in combination. Therefore, when using this as a solar cell backsheet, generation | occurrence | production of a sodium ion can be suppressed.
In particular, the reflecting sheet can highly reflect not only from the solar light irradiation side of the solar cell module but also from the opposite side (hereinafter referred to as “back surface”) from ultraviolet rays to near infrared rays. Therefore, the hydrolysis of EVA caused by near infrared rays can be suppressed, and thereby the generation of sodium ions can be further suppressed.

The reflective sheet of the present embodiment is preferably provided in the solar cell module such that the resin layer is on the EVA side and the substrate is on the outside.

Thus, the solar cell backsheet capable of highly reflecting light in a wide range of wavelengths can be used regardless of the type of solar cell.
For example, specifically, a liquid crystal solar cell such as a single crystal type or a polycrystal type among silicon-based materials that are currently widely used generates power using sunlight with a wavelength of 500 nm to 900 nm. On the other hand, a dandem type in which an amorphous type and a crystal type are combined generates power using sunlight having a wavelength of 300 nm to 900 nm. Further, the dye-sensitized type generates power using sunlight having a wavelength of 500 nm to 1500 nm.
The reflective sheet of the present embodiment can achieve high reflectivity at a wavelength of a desired power generation band as appropriate for solar cells having different maximum power generation bands as described above, and is suitable for any solar cell. Can be used.

Moreover, since the reflective sheet of this embodiment can implement | achieve a high reflectance with respect to the light of a wide wavelength, it can be used suitably also for uses, such as a reflective sheet of LED lighting.

Example A white resin composition was prepared by mixing and stirring the following components.
Byron TU02-HA (Thermoplastic resin manufactured by Toyobo Co., Ltd.) 250 parts by weight D-918 (Titanium oxide average particle size 0.26 μm manufactured by Sakai Chemical Industry Co., Ltd.) 70 parts by weight R-38L (Sakai Chemical Industry Co., Ltd.) Titanium oxide average particle size 0.4 μm) 30 parts by weight Takenate R600 (isocyanate compound manufactured by Mitsui Chemicals) 10 parts by weight propylene glycol monomethyl ether (organic solvent) 140 parts by weight

The white resin composition was printed on one side of a 188 μm thick polyethylene terephthalate (PET) film (Crisper (registered trademark) K1212 manufactured by Toyobo Co., Ltd.) so that the dried coating film might be 17 μm to 20 μm. Thereafter, the dried coating film was heated at 120 ° C. for 60 minutes to be thermally cured to obtain a white layer.
Next, a 75 μm-thick PET film (Teijin (registered trademark) Tetron (registered trademark) film VW manufactured by Teijin DuPont Films Ltd.) was laminated on the white layer, and this was thermocompression bonded. A piece was made.

Comparative Example A white resin composition was prepared by mixing and stirring the following components.
Nipponran 136 (Thermoplastic resin manufactured by Nippon Polyurethane Industry Co., Ltd.) 100 parts by weight Taipei CR-90 (Ishihara Sangyo Co., Ltd. titanium oxide) 1000 parts by weight Aluminum hydroxide 20 parts by weight Takenate R600 (Mitsui Chemicals, Inc. isocyanate) Compound) 10 parts by weight propylene glycol monoethyl ether (organic solvent) 20 parts by weight ecamide (organic solvent: amide solvent manufactured by Idemitsu Kosan Co., Ltd.) 20 parts by weight AEROSIL 200 (spherical silica manufactured by Nippon Aerosil Co., Ltd.) 20 parts by weight styrene -Maleic anhydride copolymer (styrene-based resin) 600 parts by weight BYK-A515 (Bubble Chemie Japan Co., Ltd. antifoaming agent) 20 parts by weight

The white resin composition is printed on one side of a 188 μm thick polyethylene naphthalate (PEN) base material (Teonex manufactured by Teijin DuPont Films Co., Ltd.) by screen printing so that the dry coating film has a thickness of 20 μm. And heated for 60 minutes to obtain a test piece having a white layer.

<Reflectance>
About the Example and the comparative example, the reflectance from 300 nm to 2000 nm was measured from the resin layer (resin film) side using the ultraviolet visible spectrophotometer (Shimadzu Corporation UV-3100PC) on condition of the following. The comparison results are shown in FIG.
In addition, about the Example, light was irradiated from the 75-micrometer-thick PET film side corresponding to a resin layer, and the comparative example was irradiated from the white layer side.
<Measurement conditions>
Measurement method: Diffuse reflection method Incident angle: 7 degrees Light source: Halogen lamp Detector: Photomal (300 nm to 860 nm), PbS (860 nm to 2000 nm)
Reference: Standard white plate (Labsphere, Sectralon)

<Heat generation and power generation>
Monocrystalline and polycrystalline solar cell modules were prepared using the reflective sheet according to the example as a solar cell backsheet. Note that. The single crystal type silicon size is 66.8 cm ² , and the polycrystalline silicon size is 50.0 cm ² .
About the said single crystal type and a polycrystal type solar ionization module, at the point of latitude: 31 degrees north latitude, longitude: 120 degrees east longitude, weather: fine weather, temperature: 9 to 12 degreeC, and humidity: about 88% In addition, the temperature and voltage of each solar cell module were measured periodically while being left between 9 am and 12:30 pm. Table 1 shows the temperature measurement results of the solar cell module, and Table 2 shows the voltage measurement results.
An MF47 function analog multimeter was used for voltage measurement. The unit of Table 1 is ° C., and the unit of Table 2 is DCV.

* 1 The initial value of the single crystal was not measurable (below the measurable temperature of the measuring device).

As can be seen from FIG. 3, the reflective sheet of the example can sufficiently reflect light in a wide wavelength range from ultraviolet to near infrared.
Further, as is clear from Table 1 and Table 2, the solar cell module using such a reflection sheet can suppress a decrease in power generation efficiency and a temperature increase in the usage time, and perform stable power generation over the long term. be able to.

DESCRIPTION OF SYMBOLS 1 Base material 2 White layer 3 Resin layer 10 Reflective sheet 20 Sealing material 30 Solar cell 40 Surface protection material 100 Solar cell module

Claims (7)

1. A reflective sheet comprising a substrate, a white layer formed on the substrate, and a resin layer provided on the white layer,
   The white layer includes a thermoplastic resin and a white pigment obtained by copolymerizing a monomer containing an aromatic dicarboxylic acid, a compound represented by the following general formula (1), and an aliphatic diol having 5 to 7 carbon atoms. And a white resin composition comprising: a reflective sheet.
   

   
2. The white pigment is titanium oxide;
   The titanium oxide includes titanium oxide (A) having an average particle size of 0.1 μm to 0.3 μm and titanium oxide (B) having an average particle size of 0.3 μm to 0.5 μm. Item 2. The reflection sheet according to Item 1.
3. The compounding amount of the titanium oxide (A) and the titanium oxide (B) is 17% to 20% by weight of the titanium oxide (A) and 7% of the titanium oxide (B) with respect to the total amount of the white resin composition. The reflective sheet according to claim 1 or 2, wherein the weight percentage is from 10% by weight to 10% by weight.
4. The reflection sheet according to any one of claims 1 to 3, wherein the white layer further contains at least one of aluminum hydroxide, zinc oxide, calcium carbonate, talc and barium.
5. The reflection sheet according to any one of claims 1 to 4, wherein at least one of the base material and the resin layer contains a white pigment.
6. A solar cell module using the reflection sheet according to any one of claims 1 to 5.
7. LED lighting using the reflective sheet according to any one of claims 1 to 5.

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