WO2013039233A1

WO2013039233A1 - Material for protecting photovoltaic cell

Info

Publication number: WO2013039233A1
Application number: PCT/JP2012/073727
Authority: WO
Inventors: 治赤池; 直哉二宮; 由美満倉; 雅秀小西; 畠山　研一
Original assignee: 三菱樹脂株式会社
Priority date: 2011-09-16
Filing date: 2012-09-14
Publication date: 2013-03-21
Also published as: WO2013039234A1

Abstract

A material for protecting a photovoltaic cell formed of a fluororesin film, an adhesive layer (i) comprising an adhesive (i), and a resin film having a metallic oxide layer, laminated in stated order, wherein a base material of the resin film having the metallic oxide layer has a thickness of 30 μm or less, the thickness of the adhesive layer (i) is 13-45 μm, and the tensile storage elasticity modulus of the adhesive layer (i) at 100°C, a frequency of 10 Hz, and distortion of 0.1% is 5.0×10⁴-5.0×10⁵Pa.

Description

Protective material for solar cells

The present invention relates to a solar cell protective material and a solar cell module having the protective material.

In recent years, solar cells that directly convert sunlight into electrical energy have attracted attention and are being developed from the viewpoint of effective use of resources and prevention of environmental pollution. A solar cell is usually manufactured by laminating a front protective material, a sealing material, a power generation element, a sealing material, and a back protective material in this order, and bonding and integrating them by heating and melting by vacuum lamination. The vacuum lamination is generally performed under conditions of 130 to 180 ° C. and 10 to 40 minutes.
Whether the protective material for solar cells is a front surface protective material or a back surface protective material, it is an important requirement that the solar cell protective material has excellent durability against ultraviolet rays, moisture resistance, and the like. As a solar cell protective material effective for improving the weight, impact resistance, and durability of solar cells, a material in which a weather-resistant film and a moisture-proof film are bonded together with an adhesive or a pressure-sensitive adhesive is known (for example, (See Patent Documents 1 and 2).
In Patent Document 3, a polyester adhesive is used for a moisture-proof film having a water vapor transmission rate of 0.22 [g / (m ² · day)] using a biaxially stretched polyester film as a base material. A solar cell protective material is prepared by laminating a weather-resistant polyester film and a polypropylene film on the back surface, and the moisture resistance after a 1000 hour test is evaluated at 85 ° C. and 85% humidity, and a proposal for preventing moisture degradation is made. ing.
In the example of Patent Document 4, a polyurethane adhesive layer is provided on both sides of a moisture-proof film having a water vapor transmission rate of 1 to 2 [g / (m ² · day)] based on a biaxially stretched polyester film. The surface protection material for solar cells was manufactured by laminating weather-resistant polyester films on both sides, and the barrier performance and interlayer strength after 1000 hours accelerated test at 85 ° C and 85% humidity were evaluated to prevent deterioration of both characteristics. I am making a proposal.
In Patent Document 5, a PVF film using a two-component curable polyurethane adhesive on a moisture-proof film having a water vapor transmission rate of 0.5 [g / (m ² · day)], which is also based on a biaxially stretched polyester film. After bonding, the moisture resistance and interlayer strength before and after the pressure cooker test (PCT) (severe environment test by high temperature and pressure, 105 ° C., 92 hours) are evaluated, and the proposal for preventing the deterioration of characteristics is made.

Japanese Patent No. 3978911 Japanese Patent No. 3978912 JP 2007-150084 A JP 2009-188072 A JP 2009-49252 A

In the protective material in which the above weather-resistant film and moisture-proof film are bonded with an adhesive or a pressure-sensitive adhesive, the moisture-proof film is a film (inorganic thin film) in which an inorganic thin film is deposited on a film base material in order to obtain high moisture resistance. Vapor-deposited film) is used. This inorganic thin film deposited film base material uses a film having a melting point higher than the vacuum lamination temperature, and when the thickness is thin, wrinkles and protrusions are formed on the surface of the protective material and the interface between the protective material and the sealing material due to vacuum lamination. There may be a problem of appearance failure such as occurrence or peeling between the protective material and the sealing material. On the other hand, when using a thick inorganic vapor-deposited film with a thickness of 50 μm or more, the roll length that can be handled in the unit production process is short in the production process of the moisture-proof film accompanied by vapor deposition or the decrease in light transmittance due to the increase in the thickness of the entire protective material. As a result, the production cost increases, resulting in a significant decrease in the strength and power generation efficiency of the solar cell and a decrease in the production efficiency of the protective material.
In addition, when using a thick inorganic vapor-deposited film, the thickness of the solar cell element side is thicker than the inorganic layer exhibiting the moisture-proofing effect among the total thickness of the protection material, so that the moisture inflow from the edge of the protection material increases and the moisture-proofing effect. As a result, the power generation efficiency of the solar cell is significantly reduced.
In addition, when a thin inorganic vapor deposition film with a thickness of less than 50 μm is used without using a thick inorganic vapor deposition film, a new film using an adhesive or adhesive on the back side of the inorganic vapor deposition surface is used. By bonding, the protective material can be given rigidity that can withstand the vacuum lamination process.
However, when a new film is pasted by a dry lamination process, etc., the inorganic vapor deposition surface is affected by the residual stress accumulated from the back of the moisture-proof film in the vacuum lamination process and subsequent durability tests. There was a problem that the moisture-proof performance was significantly deteriorated due to damage.

Thus, in the solar cell protective material using the conventional technology, it has not been possible to realize both the suppression of the appearance defect such as wrinkles and the solution of the moisture-proof effect and the decrease in power generation efficiency.

The problem to be solved by the present invention is to provide a solar cell protective material that has no appearance defects such as wrinkles, is excellent in appearance, and is excellent in moisture resistance, in particular, end face moisture resistance, as well as using this solar cell protection material. The object is to provide a solar cell module.

As a result of intensive studies, the inventors have made the elastic modulus of the pressure-sensitive adhesive layer used for bonding below a specific elastic modulus near the vacuum lamination temperature, and the thickness of the pressure-sensitive adhesive layer is 13 to 45 μm. It has been found that a protective material for a solar cell can be provided which prevents deterioration in appearance after vacuum lamination without using a thick inorganic vapor-deposited film, and is excellent in peel strength and moisture resistance, in particular, end face moisture resistance.

That is, the present invention
(1) A protective material for solar cells in which a fluororesin film, an adhesive layer (i) composed of an adhesive (i), and a resin film having a metal oxide layer are laminated in this order, and the metal The thickness of the base material of the resin film having an oxide layer is 30 μm or less, the thickness of the pressure-sensitive adhesive layer (i) is 13 to 45 μm, and the pressure-sensitive adhesive layer (i) is 100 ° C., frequency 10 Hz, strain 0 A protective material for solar cells having a tensile storage elastic modulus at 1% of 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa,
(2) The solar cell protective material according to (1), wherein the pressure-sensitive adhesive (i) is a pressure-sensitive adhesive containing no carboxyl group or amino group,
(3) The protective material for solar cells according to (1) or (2), wherein the base material of the resin film having the metal oxide layer is a polyester film,
(4) The water vapor permeability of the resin film having the metal oxide layer at a temperature of 40 ° C. and a relative humidity of 90% is less than 0.1 [g / (m ² · day)] (1) to (3) The solar cell protective material according to any one of
(5) Fluorine resin film, pressure-sensitive adhesive layer (i) made of pressure-sensitive adhesive (i), resin film having a metal oxide layer, pressure-sensitive adhesive layer (ii) made of pressure-sensitive adhesive or adhesive, and melting point 180 The protective material for solar cells according to any one of (1) to (4), wherein a high melting point film having a heat shrinkage rate of 0.5% or less at a temperature of 0 ° C. or higher is laminated in this order
(6) A fluororesin film, an intermediate film having a melting point of 150 ° C. or lower, an adhesive layer (i) composed of an adhesive (i), and a resin film having a metal oxide layer are laminated in this order (1) The solar cell protective material according to any one of to (5),
(7) The solar cell protective material according to (6), wherein the intermediate film has a thickness of 50 to 600 μm,
(8) The solar cell protective material according to (6) or (7), wherein the intermediate film contains a polyethylene resin as a main component.
(9) The solar cell protective material according to any one of (6) to (8), which has the pressure-sensitive adhesive layer and an intermediate film on the metal oxide layer side of the moisture-proof film,
(10) The protective material for solar cell according to any one of (1) to (9), wherein the thickness of the base material of the resin film having the metal oxide layer is thinner than the thickness of the fluororesin film,
(11) The tensile storage elastic modulus of the pressure-sensitive adhesive layer (i) comprising the pressure-sensitive adhesive (i) at 0 ° C., a frequency of 10 Hz, and a strain of 0.1% is 1.0 × 10 ⁶ to 1.0 × 10 ⁸ Pa. The solar cell protective material according to any one of (1) to (10),
(12) The solar cell protective material according to any one of (1) to (11), wherein the pressure-sensitive adhesive layer (i) comprising the pressure-sensitive adhesive (i) has a glass transition point of 0 ° C. or lower.
(13) The protective material for solar cells according to any one of (1) to (12), wherein the initial water vapor permeability is less than 0.1 [g / (m ² · day)],
(14) The solar cell protective material according to any one of (1) to (13), which is used in a vacuum lamination step having a maximum temperature of less than 150 ° C.
(15) A solar cell module having the solar cell protective material according to any one of (1) to (14),
Is to provide.

In addition, the present inventors have found that the glass transition point of the adhesive layer that bonds the films to each other in order to maintain good moisture resistance in a wide temperature range from a low temperature (eg, −40 ° C.) to a high temperature (eg, 85 ° C.). As a result, the present invention was completed.
That is, the present invention
(16) A solar cell protective material having in this order a weather-resistant layer, an adhesive layer 1, and a moisture-proof layer 1 having an inorganic layer on a substrate, and the glass transition point of the adhesive layer 1 is 0 ° C. or lower. Solar cell protective material,
(17) The solar cell protection according to (16), wherein the interlayer strength between the weather resistant layer and the moisture-proof layer 1 is 10 N / 15 mm or more after the condensation freezing test, and the degradation rate of the interlayer strength is less than 20%. Material,
(18) The solar cell protective material according to (16) or (17), wherein the adhesive layer 1 contains an acrylic pressure-sensitive adhesive.
(19) The solar cell protective material according to any one of (16) to (18), wherein the base material of the moisture-proof layer 1 is a polyester film,
(20) The solar cell protective material according to any one of (16) to (19), further comprising an adhesive layer 2 and a moisture-proof layer 2 having an inorganic layer on the substrate.
(21) The solar cell according to (20), wherein the adhesive layer 2 has a tensile storage elastic modulus of 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa at 100 ° C., a frequency of 10 Hz, and a strain of 0.1%. Protective layer,
(22) The adhesive layer 2 according to (20) or (21), wherein the tensile storage elastic modulus at 0 ° C., a frequency of 10 Hz, and a strain of 0.1% is 1.0 × 10 ⁶ to 1.0 × 10 ⁸ Pa. Solar cell protective material,
(23) The solar cell protective material according to any one of (16) to (22), wherein the weather resistant layer is a 2-ethylene-4-fluoroethylene copolymer film,
(24) The moisture vapor transmission rate of the moisture-proof layer 1 and / or the moisture-proof layer 2 at a temperature of 40 ° C. and a relative humidity of 90% is less than 0.1 [g / (m ² · day)], and after the condensation freezing test The protective material for solar cells according to any one of (16) to (23), wherein the degree of deterioration of water vapor permeability is less than 3.
(25) The solar cell protective material according to any one of (16) to (24), wherein the thickness of the base material is thinner than the thickness of the fluororesin film,
(26) The solar cell protective material according to any one of (16) to (25) and (27), (16) to (26), which is used in a vacuum lamination step having a maximum temperature of less than 150 ° C. A solar cell module comprising the solar cell protective material according to any one of the above,
Is to provide.

According to the present invention, even without using a thick inorganic thin film vapor-deposited film, the problem of poor appearance of the protective material for solar cells is solved, and the peel strength, moisture resistance, durability and weather resistance are excellent, and particularly the end face moisture resistance It is possible to provide a protective material for a solar cell that is excellent in performance.
Moreover, the solar cell module using the solar cell protective material can not only achieve a good appearance, but also prevent a decrease in power generation efficiency. In particular, the solar cell module using the solar cell protective material of the second embodiment of the present invention does not cause appearance defects such as wrinkles even by high-temperature vacuum lamination with a vacuum lamination temperature of 150 ° C. or higher. It is excellent in production efficiency without deterioration of moisture resistance.
Moreover, the solar cell protective material of the third embodiment of the present invention is excellent in flexibility and moisture resistance without generation of moisture resistance degradation and delamination over a long period of time, and simultaneously prevents the performance degradation of the solar cell module, And it is effective in improving the durability of the solar cell module.
Moreover, the solar cell protective material of the 4th embodiment of this invention is excellent in durability and a weather resistance, and can maintain favorable moisture-proof property in the wide temperature range from low temperature to high temperature.

The present invention is described in further detail below.
(First to third embodiments)
<Protective material for solar cells>
In the solar cell protective material according to the first embodiment of the present invention, a fluororesin film, an adhesive layer (i) composed of an adhesive (i), and a resin film having a metal oxide layer are laminated in this order. The substrate thickness of the resin film having the metal oxide layer is 30 μm or less, the pressure-sensitive adhesive layer (i) has a thickness of 13 to 45 μm, and the pressure-sensitive adhesive layer (i) has a temperature of 100 ° C. The tensile storage elastic modulus at a frequency of 10 Hz and a strain of 0.1% is 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa.
The solar cell protective material according to the second embodiment of the present invention includes a fluororesin film, a pressure-sensitive adhesive layer (i) comprising a pressure-sensitive adhesive (i), a resin film having a metal oxide layer, a pressure-sensitive adhesive, or an adhesive. And a high melting point film having a melting point of 180 ° C. or more and a shrinkage rate of 0.5% or less, and the pressure-sensitive adhesive layer (i) has a thickness of 13 to 45 μm. The tensile storage elastic modulus of the pressure-sensitive adhesive layer (i) at 100 ° C., frequency 10 Hz, and strain 0.1% is 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa.
The solar cell protective material according to the third embodiment of the present invention includes a fluororesin film, an intermediate film, a pressure-sensitive adhesive layer (i) comprising a pressure-sensitive adhesive (i), and a resin film having a metal oxide layer. The water vapor permeability of the resin film is 0.1 [g / (m ² · day)], the melting point of the intermediate film is 150 ° C. or less, and the pressure-sensitive adhesive layer (i) The adhesive layer (i) has a tensile storage modulus of 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa at 100 ° C., a frequency of 10 Hz, and a strain of 0.1%. is there.

[Fluorine resin film]
In the present invention, the fluororesin film is used as a weather resistant film.
As the fluororesin film, those excellent in hydrolysis resistance and weather resistance can be used without particular limitation. For example, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetra Fluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc. A film. As long as the said fluororesin film is shape | molded using the said resin, a single layer or a multilayer may be sufficient and it may be laminated | stacked with the other film.
In the vacuum lamination process, to reduce the residual strain in the weather-resistant film produced in the lamination process for manufacturing the solar cell protective material, and to obtain the effect of reducing the residual stress in the protective material layer at high temperature and high humidity It is preferable to use a film having a melting point near the temperature during vacuum lamination, that is, a film having a melting point of 180 ° C. or lower. In addition, by using a weather resistant film having the melting point within the above temperature range, the temperature in the vacuum lamination, the molecules in the film generated by the history of the force applied in the previous process and the thermal history, crystal orientation Can be relaxed and residual strain can be reduced.

In addition, as the fluororesin film, it is preferable that the characteristic change is small even in the temperature and humidity change at the time of vacuum lamination or high temperature and high humidity. Preferably used.
The thickness of the fluororesin film is generally about 20 to 200 μm, preferably 20 to 100 μm, more preferably 20 to 50 μm from the viewpoints of film handling and cost.

[Resin film having a metal oxide layer]
In the present invention, the resin film having a metal oxide layer is a film having at least one metal oxide layer made of a metal oxide on at least one surface of a substrate, and is a film having moisture resistance. By this metal oxide layer, the inner surface side of the solar cell by moisture and water permeation can be protected.

As the substrate, a resin film is preferable, and any material can be used without particular limitation as long as it is a resin that can be usually used for a solar cell member. Specifically, polyolefins such as homopolymers or copolymers such as ethylene, propylene and butene, amorphous polyolefins such as cyclic polyolefins, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), nylon 6 , Nylon 66, nylon 12, polyamide such as copolymer nylon, ethylene-vinyl acetate copolymer partial hydrolyzate (EVOH), polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polycarbonate, Examples include polyvinyl butyral, polyarylate, fluororesin, acrylic resin, and biodegradable resin. Among these, polyesters, polyamides, and polyolefins are preferable from the viewpoints of film properties and cost. Among these, from the viewpoint of film physical properties, polyester is preferable, and polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are particularly preferable.

The base material is a known additive such as an antistatic agent, a light blocking agent, an ultraviolet absorber, a plasticizer, a lubricant, a filler, a colorant, a stabilizer, a lubricant, a crosslinking agent, an antiblocking agent, an oxidation agent. An inhibitor or the like can be contained.
The base material is formed by using the raw materials and the like, but may be unstretched or stretched.

Such a substrate can be produced by a conventionally known method. For example, the raw material is melted by an extruder, extruded by an annular die or a T die, and rapidly cooled to be substantially amorphous and not oriented. A stretched film can be produced. Further, by using a multilayer die, it is possible to produce a single layer film made of one kind of resin, a multilayer film made of one kind of resin, a multilayer film made of various kinds of resins, and the like.

The unstretched film is subjected to a known method such as uniaxial stretching, tenter sequential biaxial stretching, tenter simultaneous biaxial stretching, tubular simultaneous biaxial stretching, or the like. A film stretched in a uniaxial direction or a biaxial direction can be produced by stretching in a direction perpendicular to it (horizontal axis). The draw ratio can be arbitrarily set, but the heat shrinkage at 100 ° C. is preferably 0.01 to 5%, more preferably 0.01 to 2%. Further, the thermal shrinkage at 150 ° C. is more preferably 0.01 to 5%, and particularly preferably 0.01 to 2%. Among these, from the viewpoint of film properties, biaxially stretched polyethylene naphthalate film, biaxially stretched polyethylene terephthalate, polyethylene terephthalate and / or coextruded biaxially stretched film of polyethylene naphthalate and other plastics are preferable.

In addition, it is preferable to apply | coat an anchor coating agent and to provide an anchor coat layer in the said base material for the adhesive improvement with a metal oxide thin layer. Examples of anchor coating agents include solvent-based or aqueous polyester resins, isocyanate resins, urethane resins, acrylic resins, modified vinyl resins, vinyl alcohol resins, vinyl butyral resins, ethylene vinyl alcohol resins, nitrocellulose resins, oxazoline group-containing resins, carbodiimides. A group-containing resin, a melamine group-containing resin, an epoxy group-containing resin, a modified styrene resin, a modified silicone resin, or the like can be used alone or in combination of two or more.
Anchor coating agents contain silane coupling agents, titanium coupling agents, alkyl titanates, light blockers, UV absorbers, stabilizers, lubricants, antiblocking agents, antioxidants, etc. A material obtained by copolymerizing an agent or the like with the above resin can be contained.

As a method for forming the anchor coat layer, a known coating method is appropriately adopted. For example, any method such as a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or a coating method using a spray can be used. Alternatively, the substrate may be immersed in an anchor coating agent solution. After coating, the solvent can be evaporated using a known drying method such as hot air drying at a temperature of about 80 to 200 ° C., heat drying such as hot roll drying, or infrared drying. Moreover, in order to improve water resistance and durability, the crosslinking process by electron beam irradiation can also be performed. Further, the formation of the anchor coat layer may be a method performed in the middle of the substrate production line (inline) or a method performed after manufacturing the substrate film (offline).

In the present invention, the thickness of the base material is 30 μm or less from the viewpoint of end face moisture resistance of the solar cell protective material, and from the viewpoint of preventing appearance deterioration after high-temperature vacuum lamination without using a thick inorganic thin film deposited film. It is preferably 10 to 30 μm, more preferably 12 to 25 μm, and particularly preferably 12 to 20 μm.
Furthermore, it is preferable that the thickness of the base material is thinner than the thickness of the fluororesin film, thereby obtaining a solar cell protective material excellent in flexibility. When the solar cell module using such a solar cell protective material is bent, the solar cell protective material can follow the bending, and the solar cell protective material and the sealing material are delaminated. Is unlikely to occur.

Examples of the material constituting the metal oxide layer include oxides such as silicon, aluminum, magnesium, zinc, tin, nickel, and titanium, oxide carbides, oxynitrides, oxycarbonitrides, and mixtures thereof. Silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, carbonized oxycarbide because there is no fear of leakage of current when applied to solar cells and high moisture resistance can be stably maintained. Metal oxides such as aluminum and aluminum oxynitride and mixtures thereof are preferred.
As a method for forming the metal oxide layer, any method such as a vapor deposition method and a coating method can be used, but a vapor deposition method is preferred in that a uniform thin film having a high gas barrier property can be obtained. This vapor deposition method includes methods such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). Examples of physical vapor deposition include vacuum vapor deposition, ion plating, and sputtering, and chemical vapor deposition includes plasma CVD using plasma, and a catalyst that thermally decomposes a material gas using a heated catalyst body. Examples include chemical vapor deposition (Cat-CVD).

The thickness of the metal oxide layer is preferably 40 to 1000 nm, more preferably 40 to 800 nm, and still more preferably 50 to 600 nm, from the viewpoint of stable moisture-proof performance and transparency.
In addition, the metal oxide layer can be formed into a multi-layer by using the various film formation methods mentioned above to improve moisture resistance. In that case, the same film formation method may be used, or a different film formation method may be used for each layer. However, it is effective to improve the moisture resistance and productivity by continuously performing them under reduced pressure. This is preferable.

The water vapor transmission rate of the resin film having a metal oxide layer at a temperature of 40 ° C. and a relative humidity of 90% is preferably less than 0.1 [g / (m ² · day)], more preferably 0 from the viewpoint of moisture resistance. 0.05 [g / (m ² · day)] or less, more preferably 0.03 [g / (m ² · day)] or less.
The water vapor transmission rate can be adjusted by appropriately adjusting the selection of the base material, the selection of the metal oxide constituting the metal oxide layer, the thickness of the metal oxide layer, the oxidation number of the metal oxide, and the like.
The water vapor transmission rate is measured in accordance with the conditions of JIS Z 0222 “Method of moisture permeability test for moisture-proof packaging containers” and JIS Z 0208 “Method of moisture permeability test for moisture-proof packaging materials (cup method)”. It is measured by the method described in the examples.

[Adhesive layer (i)]
In the present invention, an adhesive is a liquid property (fluidity) for adhering and adhering to an adherend by applying a slight pressure at room temperature for a short time without using water, a solvent, heat or the like. ) And a solid property (cohesive force) that resists peeling, and is distinguished from a normal adhesive. While adhesives such as solution-type adhesives, thermosetting adhesives, and hot-melt adhesives solidify due to chemical reaction, solvent volatilization, temperature changes, etc., adhesives are semi-solid and require a solidification process. In other words, the state does not change even after the bonding is formed.
The pressure-sensitive adhesive layer (i) in the present invention is a layer for bonding one side of a fluororesin film and a resin film having a metal oxide layer. The tensile storage elastic modulus of the pressure-sensitive adhesive layer (i) at 100 ° C., a frequency of 10 Hz, and a strain of 0.1% is 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa.

According to this, the deformation and stress of the moisture-proof film layer in the protective material due to the shrinkage of the sealing material can be relieved, and the propagation of stress that causes wrinkles on the surface of the fluororesin film can be prevented, and thick inorganic vapor deposition It is possible to prevent poor appearance without using a film. In addition, this stress propagation mitigation action in the vacuum lamination process also reduces the stress action on the metal oxide layer surface in contact with the pressure-sensitive adhesive layer, and it is possible to obtain the effect of preventing the deterioration of moisture resistance in the subsequent durability test. It is. Therefore, in this invention, even if it does not use the thick inorganic vapor deposition film which resists shrinkage | contraction of a sealing material, the problem of the external appearance defect of the protective material for solar cells can be eliminated.

When the tensile storage modulus of the pressure-sensitive adhesive layer (i) exceeds 5.0 × 10 ⁵ Pa, there is a possibility that the pressure-sensitive adhesive layer (i) cannot sufficiently absorb the stress generated due to film shrinkage or the like. is there. By setting the tensile storage elastic modulus of the pressure-sensitive adhesive layer (i) to 5.0 × 10 ⁵ Pa or less, the pressure generated by the shrinkage of the film can be sufficiently absorbed by the pressure-sensitive adhesive layer (i). Deterioration can be prevented. On the other hand, when the tensile storage elastic modulus is less than 5.0 × 10 ⁴ Pa, the pressure-sensitive adhesive layer (i) flows during the vacuum lamination process and protrudes greatly from the protective material to obtain a laminate having a uniform thickness. I can't.
From the above viewpoint, the tensile storage elastic modulus of the pressure-sensitive adhesive layer (i) at 100 ° C., frequency 10 Hz, and strain 0.1% is preferably 7 × 10 ⁴ Pa to 3 × 10 ⁵ Pa. Furthermore, the tensile storage elastic modulus of the pressure-sensitive adhesive layer (i) at 0 ° C., a frequency of 10 Hz, and a strain of 0.1% is preferably 1.0 × 10 ⁶ to 1.0 × 10 ⁸ Pa.
In addition, a tensile storage elastic modulus is measured by the method as described in an Example.

The tensile storage elastic modulus can be adjusted (controlled) by the component composition of the pressure-sensitive adhesive layer (i) and the crosslinking agent. By using a monomer having a high glass transition point (Tg) and increasing the amount of the crosslinking agent added, the tensile storage elastic modulus increases, and using a monomer having a low glass transition point (Tg) and reducing the amount of the crosslinking agent added. As a result, the tensile storage modulus decreases.
In the present invention, the pressure-sensitive adhesive (i) used for the pressure-sensitive adhesive layer (i) has a tensile storage elastic modulus at 100 ° C. of 5.0 × 10 ⁴ to 5 × 10 ⁵ Pa, Further, from the viewpoint of exhibiting a tensile storage elastic modulus of 1 × 10 ⁶ Pa or more in order to maintain the adhesive strength at room temperature (20 ° C.), those containing an acrylic pressure-sensitive adhesive are preferable, and the acrylic pressure-sensitive adhesive is the main component. More preferred. Here, the main component is a purpose that allows other components to be contained within a range that does not impede the effect of the present invention, and does not limit the specific content, but is generally a pressure-sensitive adhesive layer (i ) Is 50 parts by mass or more, preferably 65 parts by mass or more, more preferably 80 parts by mass or more and occupies a range of 100 parts by mass or less.

Examples of the acrylic pressure-sensitive adhesive include a main monomer component having a low glass transition point (Tg) that imparts tackiness, a comonomer component having a high Tg that imparts adhesiveness and cohesive force, and a functional group-containing monomer for improving crosslinking and adhesion. What consists of the polymer or copolymer (henceforth "acrylic (co) polymer") which mainly has a component is preferable.
Examples of the main monomer component of the acrylic pressure-sensitive adhesive include alkyl acrylate esters such as ethyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, benzyl acrylate, and the like. And alkyl methacrylates such as butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. These may be used alone or in combination of two or more.

Examples of the comonomer component of the acrylic pressure-sensitive adhesive include methyl acrylate, methyl methacrylate, ethyl methacrylate, vinyl acetate, styrene, acrylonitrile and the like. These may be used alone or in combination of two or more.
Examples of the functional group-containing monomer component of the acrylic pressure-sensitive adhesive include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid, 2-hydroxyethyl (meth) acrylate, and 2-hydroxypropyl (methacrylic acid). ) Hydroxyl group-containing monomers such as acrylate and N-methylolacrylamide, acrylamide, methacrylamide, glycidyl methacrylate and the like. These may be used alone or in combination of two or more.

Examples of the initiator used for polymerization of the monomer component of the acrylic pressure-sensitive adhesive include azobisisobutylnitrile, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, and the like. Moreover, there is no restriction | limiting in particular about the copolymerization form of the acrylic (co) polymer used as the main component of the said acrylic adhesive, Any of a random, a block, and a graft copolymer may be sufficient.
The molecular weight when the acrylic pressure-sensitive adhesive is the above-mentioned acrylic (co) polymer is preferably 300,000 to 1,500,000 in terms of weight average molecular weight, more preferably 400,000 to 1,000,000. preferable. By setting the weight average molecular weight within the above range, adhesion to the adherend and adhesion durability can be secured, and floating and peeling can be suppressed.

Further, in the acrylic (co) polymer, the content of the functional group-containing monomer component unit is preferably in the range of 1 to 25% by mass. By making this content within the above range, the adhesion and the degree of crosslinking with the adherend are ensured, and the tensile storage elastic modulus of the adhesive layer, which is an essential condition in the present invention, is 5.0 × 10 at 100 ° C. The value can be ⁴ to 5.0 × 10 ⁵ Pa.

Furthermore, the present inventors have found that the carboxyl group or amino group contained in the pressure-sensitive adhesive used affects the moisture-proof performance of the protective material in the high-temperature and high-humidity test. If the pressure-sensitive adhesive (i) contains a reactive carboxyl group or amino group, the pressure-sensitive adhesive is likely to be hydrolyzed, whereby the metal oxide layer is likely to deteriorate, and the moisture-proof performance may be reduced. is there. In particular, in a high temperature and high humidity environment, hydrolysis reaction is likely to be caused by moisture. Therefore, the pressure-sensitive adhesive (i) is preferably a pressure-sensitive adhesive that does not contain a carboxyl group or an amino group. Furthermore, it is more preferable that it is an adhesive which does not contain a carboxyl group and an amino group.

The pressure-sensitive adhesive in the present invention preferably contains an ultraviolet absorber. As the ultraviolet absorber that can be used, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5), which has good compatibility with acrylic pressure-sensitive adhesives and hardly causes bleed-out after compounding. -Butylphenyl) benzotriazole, 2- (2-hydroxy-5-octylphenyl) benzotriazole, 2- (3-tert-butyl-2-hydroxy-5-methylphenyl) -5-chlorobenzotriazole, 2- ( Benzotriazoles such as 3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, benzophenones such as 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine-2 Yl] -5- (octyloxy) phenol, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol and the like, P-tert-butyl Among salicylate-based ultraviolet absorbers such as phenyl salicylate and phenyl salicylate, one kind or a mixture of two or more kinds can be used. The blending of the ultraviolet absorber is preferably 0.1 to 10 parts by mass, more preferably 1 to 7 parts by mass in terms of solid content with respect to 100 parts by mass of the acrylic polymer. If the amount is less than 0.1 parts by mass, satisfactory ultraviolet absorption performance cannot be obtained. If the amount is 10 parts by mass or more, the obtained ultraviolet absorption performance is not improved, and the adhesive performance and durability are extremely reduced.
Moreover, it is preferable that the glass transition point of an adhesive layer (i) is 0 degrees C or less. If the glass transition point of the pressure-sensitive adhesive layer (i) exceeds 0 ° C., it becomes impossible to maintain good moisture resistance by the metal oxide layer over a wide temperature range from low temperature (eg −40 ° C.) to high temperature (eg 85 ° C.). There is a risk. The glass transition point is more preferably −40 to 0 ° C. in order to prevent weakening of the pressure-sensitive adhesive layer (i).
The glass transition point of the adhesive layer (i) is specifically determined by the method described in the examples.
The glass transition point can be adjusted by appropriately adjusting the type and molecular weight of the pressure-sensitive adhesive (i).

In the present invention, the pressure-sensitive adhesive layer (i) may be formed by directly applying the pressure-sensitive adhesive (i) to the metal oxide layer of the resin film having the fluorine resin film or the metal oxide layer. In addition, the adhesive (i) is applied to the release-treated surface of the release sheet that has been subjected to the release treatment, and this is bonded to the metal oxide layer of the resin film having a fluorine-based resin film or metal oxide layer. Can be formed.

The pressure-sensitive adhesive to be coated (hereinafter referred to as coating liquid) includes an organic solvent system, an emulsion system, and a solvent-free system, but an organic solvent system is preferable for uses such as solar cell members that are required to have water resistance. .
Examples of the organic solvent used in the organic solvent-based coating liquid include toluene, xylene, methanol, ethanol, isobutanol, n-butanol, acetone, methyl ethyl ketone, ethyl acetate, and tetrahydrofuran. These may be used alone or in combination of two or more.

For the convenience of coating, the coating liquid is preferably prepared using these organic solvents so that the solid content concentration is in the range of 10 to 50% by mass.
Coating of the coating liquid is, for example, conventionally known coating methods such as bar coating, roll coating, knife coating, roll knife coating, die coating, gravure coating, air doctor coating, doctor blade coating, etc. It can be done by a method.
After the application, the pressure-sensitive adhesive layer (i) is formed by drying treatment usually at a temperature of 70 to 110 ° C. for about 1 to 5 minutes.

The thickness of the pressure-sensitive adhesive layer (i) is 13 μm or more, preferably 15 μm or more, more preferably 20 μm or more from the viewpoint of obtaining sufficient adhesive force. In addition, the structural change that occurs in the pressure-sensitive adhesive layer (i) during the high-temperature and high-humidity test prevents the stress on the metal oxide layer surface of the resin film having a metal oxide layer from increasing, resulting in inferior moisture resistance. Therefore, the thickness is 45 μm or less, preferably 30 μm or less. In particular, when the thickness of the pressure-sensitive adhesive layer (i) exceeds 50 μm, the stress on the metal oxide layer surface acts as a product of the thickness of the pressure-sensitive adhesive layer (i) and the stress generated in the pressure-sensitive adhesive layer (i). The decrease in moisture resistance during the durability test is significant.

[High melting point film]
The protective material for a solar cell of the present invention preferably has a high melting point film on the side opposite to the fluorine resin film. The high melting point film used has a melting point of 180 ° C. or higher and a shrinkage rate of 0.5% or lower. The heat shrinkage rate of the film is preferably 0.5% or less in both the length direction and the width direction.
By using such a high melting point film, rigidity that can withstand the vacuum lamination process can be imparted to the solar cell protective material, and the stress generated in the high melting point film is alleviated and a resin film having a metal oxide layer Propagation of stress to can be prevented. According to this, the moisture-proof performance fall of the resin film which has a metal oxide layer can be suppressed.

The thermal shrinkage rate of the high melting point film is 0.5% or less, preferably 0.4% or less, from the viewpoint of reducing the occurrence of residual stress in the vacuum lamination process and preventing the curling of the solar cell protective material. More preferably, it is 0.3% or less. In addition, a heat shrinkage rate is measured by the method as described in an Example.

It does not specifically limit as a material of a high melting point film, For example, polyester, polyamide, polyphenylene sulfide, etc. are mentioned. Among them, preferred specific examples include polyethylene terephthalate (melting point: 260 ° C.), polyethylene naphthalate (melting point: 262 ° C.), and the like.
The high melting point film may be a single layer or a laminated structure having a plurality of high melting point films. The thickness of the high melting point film is from 25 to 250 μm from the viewpoint of preventing wrinkles after vacuum lamination and curling of solar cell protective materials. It is preferably 38 to 220 μm, more preferably 50 to 200 μm.

[Adhesive layer (ii)]
In the present invention, the adhesive layer (ii) is a layer for bonding the back surface of the metal oxide layer surface of the resin film having a metal oxide layer and a high melting point film using an adhesive or an adhesive.
When using a pressure-sensitive adhesive, it is desirable to use the same as the pressure-sensitive adhesive (i). When using a pressure-sensitive adhesive, a polyurethane-based adhesive having excellent hydrolysis resistance, It is desirable to use ii) in a range where the tensile storage elastic modulus is the same as that of the pressure-sensitive adhesive layer (i).
The adhesive layer (ii) made of an adhesive or an adhesive is formed by directly applying an adhesive to the back surface of a metal oxide layer surface of a resin film having a metal oxide layer or a high melting point film. Alternatively, the adhesive may be applied to the release-treated surface of the release sheet that has been subjected to the release treatment, and this may be bonded to the back surface of the metal oxide layer surface of the resin film having the metal oxide layer or a high melting point film. Can be formed.
The thickness of the adhesive layer (ii) is preferably 13 μm or more, more preferably 15 μm or more, and still more preferably 20 μm or more when a pressure-sensitive adhesive is used from the viewpoint of obtaining sufficient adhesive force. In order to prevent moisture from entering from the end face, the thickness is preferably 50 μm or less, and more preferably 30 μm or less, from the viewpoint of reducing the thickness of the lower layer side from the moisture-proof film as much as possible. Moreover, when using an adhesive agent, Preferably it is 4 micrometers or more, More preferably, it is 6 micrometers or more, More preferably, it is 8 micrometers or more. In order to prevent moisture from entering from the end face, the thickness on the lower layer side of the moisture-proof film is preferably as thin as possible, and the thickness is preferably 10 μm or less, and an adhesive is used from the viewpoint of preventing moisture from entering from the end face. It is desirable to do.

[Intermediate film]
The solar cell protective material of the present invention preferably has an intermediate film between the fluororesin film and the pressure-sensitive adhesive layer (i). The intermediate film can be directly bonded to the pressure-sensitive adhesive layer formed on the metal oxide layer surface of the moisture-proof film. Since the intermediate film has a melting point of 150 ° C. or lower, it is melted in a vacuum lamination step, and may be provided on the back side from the intermediate film by a pressure-down adhesive layer, moisture-proof film, and further from the moisture-proof film. An end-sealed film is formed on the side surfaces of the film and the like to protect the pressure-sensitive adhesive layer, the base material of the moisture-proof film, and the like, thereby preventing the moisture-proof property from decreasing and delamination from occurring.
From the above, it is preferable that the intermediate film is excellent in weather resistance and wet heat resistance and has good adhesion to each layer forming the solar cell protective material. From the above viewpoint, it is the same as the solar cell sealing material. It is desirable to use a film.

From the above viewpoint, the melting point of the intermediate film is preferably 120 ° C. or less, more preferably 110 ° C. or less, and further preferably 100 ° C. or less. The lower limit is usually 50 ° C. and preferably 60 ° C. The melting point of the intermediate film is particularly preferably 60 to 110 ° C.
By using an intermediate film with a melting point within the above temperature range, it remains at the temperature at the time of vacuum lamination, relaxing the molecular and crystal orientation in the film caused by the history of the force applied in the previous process and the thermal history. The effect of reducing distortion can also be obtained.

As the intermediate film, it is desirable that it is rich in flexibility and excellent in ultraviolet rays and humidification durability in consideration of use as a solar cell surface protective material. Examples of such an intermediate film include a film containing ethylene-vinyl acetate or polyethylene as a main component, for example, a film containing 50% by mass or more and less than 100% by mass. Furthermore, from the above viewpoint, a film containing polyethylene having a low melting point as a main component, for example, a film containing 50% by mass or more and less than 100% by mass is preferable. Of these, a resin composition in which an ultraviolet absorber or a colorant is kneaded with a resin such as low density polyethylene (LDPE) or ethylene-α-olefin copolymer is preferably used. LDPE) or an ethylene-α-olefin copolymer as a main component, for example, a film containing 50% by mass or more and less than 100% by mass is particularly preferable.

In addition, as said ultraviolet absorber used for an intermediate | middle film, although various commercial items are mention | raise | lifted, various types, such as a benzophenone series, a benzotriazole series, a triazine series, and a salicylic acid ester series, can be mentioned. Examples of benzophenone ultraviolet absorbers include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n. -Dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2 4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, etc. It is possible.

Examples of the benzotriazole ultraviolet absorber include hydroxyphenyl-substituted benzotriazole compounds such as 2- (2-hydroxy-5-methylphenyl) benzotriazole and 2- (2-hydroxy-5-tert-butylphenyl). Benzotriazole, 2- (2-hydroxy-3,5-dimethylphenyl) benzotriazole, 2- (2-methyl-4-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3-methyl-5-t- Butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, etc. be able to. Examples of triazine ultraviolet absorbers include 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, 2- ( Examples include 4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol. Examples of salicylic acid esters include phenyl salicylate and p-octylphenyl salicylate. The amount of the ultraviolet absorber is usually about 0.01 to 2.0% by mass in the intermediate film, and preferably 0.05 to 0.5% by mass.

A hindered amine light stabilizer is preferably used as a weather stabilizer that imparts weather resistance in addition to the ultraviolet absorber. A hindered amine light stabilizer does not absorb ultraviolet rays like an ultraviolet absorber, but exhibits a remarkable synergistic effect when used together with an ultraviolet absorber.

Examples of hindered amine light stabilizers include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly [{6- (1,1,1 3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {{2, 2,6,6-tetramethyl-4-piperidyl} imino}], N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2, 6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2- (3 , 5-di-tert-4 Hydroxybenzyl) -2-n-butyl malonic acid bis (1,2,2,6,6-pentamethyl-4-piperidyl) and the like. The amount of the hindered amine light stabilizer added is usually about 0.01 to 0.5% by mass in the intermediate film, preferably 0.05 to 0.3% by mass.

In the present invention, the thickness of the intermediate film is 50 μm or more from the viewpoint of easy handling of the film, preferably 100 μm or more, more preferably 200 μm or more. Preferably it is 300 micrometers or more. The upper limit is not particularly limited, but is usually 500 μm from the viewpoint of handling. The thickness of the intermediate film is preferably 100 to 500 μm from the above.

(Fourth embodiment)
<Protective material for solar cells>
The solar cell protective material according to the fourth embodiment of the present invention is a solar cell protective material having a weatherproof layer, an adhesive layer 1 and a moisture-proof layer 1 having an inorganic layer on a base material in this order. It is a solar cell protective material whose glass transition point of the said adhesive layer 1 is 0 degrees C or less.

[Weatherproof layer]
In the present invention, examples of the weather resistant layer include a weather resistant resin composition coating layer and a weather resistant film, and a weather resistant film is preferred.
In the present invention, the weather-resistant film can be used without limitation as long as it has hydrolysis resistance and weather resistance. For example, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), Tetrafluoroethylene / hexafluoropropylene copolymer (FEP), ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc. Fluorine resin; Polyester such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); Polycarbonate; Acrylic resin such as polymethyl methacrylate (PMMA); Films of various resins such as polyamide Door can be. The weather resistant film may contain two or more of these resins, or may be a laminated film of two or more films.

In order to obtain the effect of reducing the residual strain of the weathering layer generated in the lamination process of manufacturing the solar cell protective material in the vacuum lamination process and reducing the residual stress in the protective sheet at high temperature and high humidity, vacuum lamination It is preferable to use a film having a melting point near the time temperature, that is, a film having a melting point of 180 ° C. or lower. In addition, by using a weather-resistant film having a melting point within the above temperature range, the molecular and crystal orientation in the film caused by the history of the force applied in the previous process and the thermal history at the temperature during vacuum lamination. The residual strain can be reduced by relaxation.

Further, as the weather resistant film, it is preferable that the change in characteristics is small even in the temperature / humidity change at the time of vacuum lamination or high temperature and high humidity. used.
Furthermore, the weather resistant film is a known additive, for example, an antistatic agent, an ultraviolet absorber, a plasticizer, a lubricant, a filler, a colorant, a stabilizer such as a light stabilizer, a lubricant, a crosslinking agent, an antiblocking agent, An antioxidant etc. can be contained. Moreover, you may laminate | stack the resin layer containing these various additives.
The thickness of the weather-resistant layer is generally about 20 to 200 μm. In the case of a weather-resistant film, it is preferably 20 to 100 μm, more preferably 20 to 50 μm from the viewpoint of ease of handling and cost.

[Dampproof layer]
The moisture-proof layer 1 according to the present invention is a layer having at least one inorganic layer on at least one surface of a substrate, and is a layer having moisture resistance. The inorganic layer can protect the inner surface side of a solar cell or the like due to moisture and water permeation.
In addition, the moisture-proof layer 1 is adhere | attached on the above-mentioned weather resistance layer through the contact bonding layer 1 mentioned later. Further, the moisture-proof layer 1 and the moisture-proof layer 2 described below may be collectively referred to as “moisture-proof layer”.

As the base material of the moisture-proof layer, a resin film is preferable, and as a material thereof, a resin that can be used for packaging materials such as ordinary packaging materials and electronic devices, solar cell members, electronic paper members, and organic EL members. If it can be used, there is no particular limitation. Specifically, polyolefins such as homopolymers or copolymers such as ethylene, propylene and butene; amorphous polyolefins such as cyclic polyolefins; polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); nylon 6 , Polyamides such as nylon 66, nylon 12, copolymer nylon; ethylene-vinyl acetate copolymer partial hydrolyzate (EVOH), polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polycarbonate, polyvinyl Examples include butyral, polyarylate, fluororesin, acrylic resin, and biodegradable resin. Among these, polyesters, polyamides, and polyolefins are preferable from the viewpoints of film properties and cost. Among these, from the viewpoint of film physical properties, polyester is preferable, and polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are particularly preferable.

In addition, the base material is a known additive such as an antistatic agent, a light blocking agent, an ultraviolet absorber, a plasticizer, a lubricant, a filler, a colorant, a stabilizer, a lubricant, a crosslinking agent, an antiblocking agent, an oxidation agent. An inhibitor or the like can be contained.
The resin film as the substrate may be unstretched or stretched.

The unstretched film is subjected to a known method such as uniaxial stretching, tenter sequential biaxial stretching, tenter simultaneous biaxial stretching, tubular simultaneous biaxial stretching, or the like. A film stretched in a uniaxial direction or a biaxial direction can be produced by stretching in a direction (horizontal axis) perpendicular thereto. The draw ratio can be arbitrarily set, but the heat shrinkage at 100 ° C. is preferably 0.01 to 5%, more preferably 0.01 to 2%. Among these, from the viewpoint of film properties, biaxially stretched polyethylene naphthalate film, biaxially stretched polyethylene terephthalate film, coextruded biaxially stretched film of polyethylene naphthalate and polyethylene terephthalate, or coextrusion biaxially of these resins and other resins A stretched film is preferred.

In the present invention, the thickness of the substrate is 30 μm or less, preferably 10 to 30 μm, more preferably 12 to 25 μm, and still more preferably 12 to 20 μm, from the viewpoint of moisture resistance of the end face of the protective sheet.
Furthermore, when the thickness of the base material of the moisture-proof layer 1 is smaller than the thickness of the weatherproof layer, a solar cell protective material excellent in flexibility is obtained, and when the solar cell module is bent, the solar cell protective material is The bending can be followed, and delamination between the solar cell protective material and the sealing material hardly occurs, which is preferable. In particular, it is more preferable for the reason described above that both the thickness of the base material of the moisture-proof layer 1 and the thickness of the base material of the moisture-proof layer 2 are thinner than the thickness of the weather-resistant layer.

In addition, it is preferable to provide an anchor coat layer by applying an anchor coat agent to the base material in order to improve adhesion with the inorganic layer. Examples of the anchor coating agent include solvent-based or aqueous polyester resins, isocyanate resins, urethane resins, acrylic resins, vinyl resins, vinyl alcohol resins, and other alcoholic hydroxyl group-containing resins, vinyl butyral resins, nitrocellulose resins, oxazoline group-containing resins, Examples thereof include carbodiimide group-containing resins, methylene group-containing resins, epoxy group-containing resins, styrene resins, and silicone resins. These can be used alone or in combination of two or more. In addition, the anchor coat layer contains a silane coupling agent, a titanium coupling agent, an alkyl titanate, an ultraviolet absorber, a stabilizer such as a weather resistance stabilizer, a lubricant, an anti-blocking agent, an antioxidant, etc., if necessary. can do.

As a method for forming the anchor coat layer, a known coating method is appropriately adopted. For example, any method such as a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, and a coating method using a spray can be used. Alternatively, the substrate may be immersed in a resin solution. After coating, the solvent can be evaporated using a known drying method such as hot air drying at a temperature of about 80 to 200 ° C., heat drying such as hot roll drying, or infrared drying. Moreover, in order to improve water resistance and durability, the crosslinking process by electron beam irradiation can also be performed. Further, the formation of the anchor coat layer may be a method performed in the middle of the substrate production line (inline) or a method performed after the substrate production (offline).

Examples of inorganic substances constituting the inorganic layer include silicon, aluminum, magnesium, zinc, tin, nickel, titanium, and oxides, carbides, nitrides, oxycarbides, oxynitrides, oxycarbonitrides, diamond-like carbons thereof. Or a mixture thereof, but silicon oxide, silicon oxide carbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, carbon oxide carbonization because there is no fear of leakage of current when applied to solar cells. Inorganic oxides such as aluminum and aluminum oxynitride, nitrides such as silicon nitride and aluminum nitride, diamond-like carbon, and mixtures thereof are preferred. In particular, silicon oxide, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, silicon nitride, aluminum oxide, aluminum oxycarbide, aluminum oxynitride, aluminum nitride, and mixtures thereof can maintain high moisture resistance stably. preferable.
As the method for forming the inorganic layer, any method such as a vapor deposition method and a coating method can be used, but the vapor deposition method is preferred in that a uniform thin film having a high gas barrier property can be obtained. This vapor deposition method includes methods such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). Examples of physical vapor deposition include vacuum vapor deposition, ion plating, and sputtering, and chemical vapor deposition includes plasma CVD using plasma, and a catalyst that thermally decomposes a material gas using a heated catalyst body. Examples include chemical vapor deposition (Cat-CVD).
Further, the inorganic layer may be a single layer or a multilayer, and the multilayer can be formed by using the various film forming methods mentioned above to improve moisture resistance. In that case, the same film formation method may be used, or a different film formation method may be used for each layer. However, it is effective to improve the moisture resistance and productivity by continuously performing them under reduced pressure. This is preferable.
Moreover, when an inorganic layer is a multilayer, each layer may consist of the same inorganic substance, or may consist of a different inorganic substance.

The thickness of the inorganic layer is preferably 10 to 1000 nm, more preferably 20 to 800 nm, and even more preferably 30 to 600 nm from the viewpoint of high moisture-proof performance and transparency. *

As described above, the moisture permeability of the moisture-proof layer is adjusted by appropriately selecting the inorganic material constituting the inorganic layer, the thickness of the inorganic layer, the thickness of the moisture-proof layer, the oxidation number of the inorganic layer, and the like. be able to.

From the viewpoint of moisture resistance, the water vapor transmission rate of the moisture-proof layer at a temperature of 40 ° C. and a relative humidity of 90% is preferably less than 0.1 [g / (m ² · day)], more preferably 0.05 [g / ( m ² · day)] or less, and more preferably 0.03 [g / (m ² · day)] or less.
Adjustment of the water vapor transmission rate of the moisture-proof layer is performed by appropriately adjusting the selection of the base material, the selection of the inorganic substance constituting the inorganic layer, the thickness of the inorganic layer, the thickness of the moisture-proof layer, the oxidation number of the inorganic layer, and the like. be able to.
In the moisture-proof layer 1 and / or the moisture-proof layer 2, the degree of deterioration of the water vapor transmission rate from the initial water vapor transmission rate after the condensation freezing test is preferably less than 3, and more preferably 2 or less.
The water vapor transmission rate is measured in accordance with the conditions of JIS Z 0222 “Method of moisture permeability test for moisture-proof packaging containers” and JIS Z 0208 “Method of moisture permeability test for moisture-proof packaging materials (cup method)”. It is measured by the method described in the examples.

[Adhesive layer 1]
In this invention, the glass transition point of the contact bonding layer 1 shall be 0 degrees C or less. When the glass transition point of the adhesive layer 1 exceeds 0 ° C., it becomes impossible to maintain good moisture resistance by the moisture-proof layer in a wide temperature range from low temperature (eg −40 ° C.) to high temperature (eg 85 ° C.). The glass transition point is more preferably −40 to 0 ° C. for preventing brittleness of the adhesive and the pressure-sensitive adhesive layer.
The glass transition point of the adhesive layer 1 is specifically determined by the method described in the examples.
The tensile storage elastic modulus of the adhesive layer 1 at 0 ° C., frequency 10 Hz, and strain 0.1% is preferably 1.0 × 10 ⁶ to 1.0 × 10 ⁸ Pa. More preferably, the tensile storage elastic modulus at a temperature of 10 ° C., a frequency of 10 Hz, and a strain of 0.1% is 5.0 × 10 ⁴ to 5.0 × 10 ⁵ Pa. When the tensile storage modulus at 0 ° C., frequency 10 Hz, and strain 0.1% is within the above range, stress generated by film shrinkage and the like can be sufficiently absorbed by the pressure-sensitive adhesive layer at low temperature, and moisture-proof Can be prevented. Further, when the tensile storage modulus at 100 ° C., frequency 10 Hz, and strain 0.1% is within the above range, the pressure generated by the shrinkage of the film can be sufficiently absorbed by the pressure-sensitive adhesive layer at high temperature, and moisture-proof Deterioration can be prevented.

The adhesive layer 1 is composed of an adhesive or an adhesive. The pressure-sensitive adhesive is also called a pressure-sensitive adhesive (pressure-sensitive adhesive), and can be bonded by applying a slight pressure at room temperature for a short time without using water, solvent, heat or the like. While adhesives such as solution-type adhesives, thermosetting adhesives, and hot-melt adhesives solidify due to chemical reactions, solvent volatilization, temperature changes, etc., pressure-sensitive adhesives are semi-solid and remain in their state after bonding Does not change, no solidification process is required, and the state does not change even after the bonding is formed. Hereinafter, in this specification, it distinguishes from an adhesive agent.

The pressure-sensitive adhesive according to the present invention preferably includes an acrylic pressure-sensitive adhesive, and more preferably includes an acrylic pressure-sensitive adhesive as a main component. Here, the main component is a purpose that allows other components to be included within a range that does not impede the effects of the present invention, and does not limit the specific content, but generally the configuration of the adhesive layer 1. When the total component is 100 parts by mass, it is 50 parts by mass or more, preferably 65 parts by mass or more, more preferably 80 parts by mass or more and occupies a range of 100 parts by mass or less.

Acrylic pressure-sensitive adhesives include a main monomer component having a low glass transition point (Tg) that provides tackiness, a comonomer component having a high Tg that provides adhesion and cohesion, and a functional group-containing monomer component for improving crosslinking and adhesion. Of these, a polymer or copolymer (hereinafter referred to as “acrylic (co) polymer”) is preferred.
Examples of the main monomer component of the acrylic pressure-sensitive adhesive include alkyl acrylates such as ethyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, and benzyl acrylate, And alkyl methacrylates such as butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. These may be used alone or in combination of two or more.

Examples of the comonomer component of the acrylic pressure-sensitive adhesive include methyl acrylate, methyl methacrylate, ethyl methacrylate, vinyl acetate, styrene, acrylonitrile and the like. These may be used alone or in combination of two or more.
Examples of the functional group-containing monomer component of the acrylic pressure-sensitive adhesive include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid, 2-hydroxyethyl (meth) acrylate, and 2-hydroxypropyl (meth). Examples thereof include hydroxyl group-containing monomers such as acrylate and N-methylolacrylamide, acrylamide, methacrylamide, and glycidyl methacrylate. These may be used alone or in combination of two or more.

Examples of the initiator used for polymerization of the monomer component of the acrylic pressure-sensitive adhesive include azobisisobutylnitrile, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, and the like. Moreover, there is no restriction | limiting in particular about the copolymerization form of the acrylic (co) polymer used as the main component of the said acrylic adhesive, Any of a random, a block, and a graft copolymer may be sufficient.
The molecular weight when the acrylic pressure-sensitive adhesive is the above-mentioned acrylic (co) polymer is preferably 300,000 to 1,500,000 in terms of weight average molecular weight, more preferably 400,000 to 1,000,000. . By setting the weight average molecular weight within the above range, adhesion to the adherend and adhesion durability can be secured, and floating and peeling can be suppressed.

Further, in the acrylic (co) polymer, the content of the functional group-containing monomer component unit is preferably in the range of 1 to 25% by mass. By making this content within the range, the adhesion and the degree of crosslinking with the adherend are ensured, and the tensile storage elastic modulus in the low temperature region at 0 ° C., frequency 10 Hz, strain 0.1% of the adhesive layer 1 is obtained. 1.0 × 10 ⁶ to 1.0 × 10 ⁷ Pa.

As mentioned above, the adhesive according to the present invention includes adhesives such as solution-type adhesives, thermosetting adhesives, hot-melt adhesives, etc., which are solidified by chemical reaction, solvent evaporation, temperature change, etc. To do. The adhesive preferably includes a polyurethane adhesive, and more preferably includes a polyurethane adhesive as a main component. Here, the main component is a purpose that allows other components to be included within a range that does not impede the effects of the present invention, and does not limit the specific content, but generally the configuration of the adhesive layer 1. When the total component is 100 parts by mass, it is 50 parts by mass or more, preferably 65 parts by mass or more, more preferably 80 parts by mass or more and occupies a range of 100 parts by mass or less.
As the polyurethane adhesive, a type in which the main agent and the curing agent are solidified by a chemical reaction is preferable. As the main agent, a polyol having a molecular weight of 400 to 20000 is preferably used, and a polyol having a molecular weight of 600 to 10,000 is more preferably used in consideration of a balance between coating film formability and reactivity during curing.
Specific examples of the main agent of the adhesive include a composition containing polycarbonate polyol, polyether polyol, polyacryl polyol, polyurethane polyol or polyester polyol.

Polycarbonate polyol can be obtained, for example, by copolymerizing diphenyl carbonate and diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol (NPG), and cyclohexanediol. It can also be obtained by copolymerizing polycaprolactone polyol and polycarbonate diol.

The polyether polyol can be obtained, for example, by performing ring-opening polymerization of alkylene oxide such as ethylene oxide, propylene oxide, and tetrahydrofuran using an alkali catalyst or an acid catalyst as a catalyst. As the active hydrogen-containing compound serving as a starting material for the ring-opening polymerization, polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol can be used.

The polyacrylic polyol can be obtained by copolymerizing a (meth) acrylic acid ester having a hydroxyl group and another monomer. Examples of the (meth) acrylic acid ester having a hydroxyl group include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Examples of other monomers include methyl methacrylate, butyl methacrylate, and cyclohexyl methacrylate having an alicyclic structure.

Polyurethane polyol can be obtained by urethanization reaction of diol and diisocyanate at a ratio of hydroxyl group to isocyanate group of 1 or more. The diol component and the diisocyanate component can be selected in consideration of the fluidity of the polyurethane polyol and the solubility in a solvent. The diol component is preferably a diol having a primary hydroxyl group such as propylene glycol, tetramethylene glycol, or neopentyl glycol. Examples of the diisocyanate component include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic isocyanates.

Examples of the polyester polyol include dicarboxylic acid compounds such as succinic acid, glutaric acid, adipic acid, isophthalic acid (IPA), and terephthalic acid (TPA), and diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexanediol. Alternatively, it can be obtained by copolymerizing with polytetramethylene glycol or the like.

An adhesive using polyester polyol as a raw material is preferable in terms of high adhesion to an adherend, but from the viewpoint of suppressing thermal deterioration due to hydrolysis of ester bonds, a polyester polyol having a small number of ester bond groups that can serve as hydrolysis points. It is desirable to select. For example, it is desirable to have a glycol having a long alkyl chain such as neopentyl glycol (NPG) and a glycol having an alicyclic structure such as 1,4-cyclohexanedimethanol.
Furthermore, it is desirable to select a hydrolysis-resistant polyester polyol that includes a polyether structure in the main chain structure, such as polytetramethylene glycol (PTMG). The molecular weight per ester group of such a polyester polyol is preferably 100 to 5,000, more preferably 120 to 3,000.
As a polyol, what contains at least 1 sort (s) chosen from a polycarbonate polyol, a polyether polyol, and a polyurethane polyol from viewpoints, such as heat stability and humidity stability, is preferable.

Further, those containing 30% by mass or more of at least one selected from polycarbonate polyol, polyether polyol and polyurethane polyol are more preferred, and those containing 30 to 70% by mass are particularly preferred.
Further, it is preferable to add 0 to 30% by mass of other components. As the other components, acrylic resins, epoxy resins, polyolefins and the like for improving adhesion are preferable. Furthermore, a styrene-butadiene rubber excellent in high cold resistance and hydrolysis resistance can be preferably used.

As the curing agent, diisocyanate is preferable, and any of aliphatic diisocyanate, aromatic diisocyanate and alicyclic diisocyanate can be preferably used. Specific examples of the aliphatic diisocyanate include hexamethylene diisocyanate (HDI). Specific examples of the aromatic diisocyanate include xylylene diisocyanate (XDI) and diphenylmethane diisocyanate (MDI). Specific examples of the alicyclic diisocyanate include isophorone diisocyanate (IPDI) and dicyclohexylmethane diisocyanate (H12MDI).
As the polyurethane-based adhesive, a polycarbonate-based polyurethane adhesive obtained by reacting a polycarbonate polyol and diisocyanate is more preferable from the viewpoints of thermal stability, humidity stability, and the like. In particular, HDI having a flexible methylene chain is preferably used as the diisocyanate from the viewpoint of obtaining a sufficient crosslinking density even during curing.
Moreover, in order to obtain a more thermally stable adhesive layer, it is preferable to use a material containing an epoxy compound as a main component.
In order for the crosslinking reaction to proceed sufficiently during the curing of the adhesive, the hydroxyl group of the main polyol must be sufficiently close to the isocyanate group of the curing agent. That is, the curing agent needs to penetrate between the polymer chains of the main polyol. For this purpose, the molecular weight of the curing agent is preferably smaller than that of the polyol, and the molecular weight of the diisocyanate contained in the curing agent is preferably 300 to 10,000, more preferably 1,000 to 5,000.
In order to obtain a sufficient crosslinking density and to suppress the number of remaining functional groups, based on the idea of using a main agent and a curing agent having different molecular weights, for example, a method using a mixture of a plurality of polyols having different molecular weights as the main agent is preferable. .

The physical properties of the adhesive as described above are preferably (main agent viscosity / curing agent viscosity) or (curing agent viscosity / main agent viscosity) of 5 or more, and more preferably 10 or more. The viscosity of the main agent is preferably 100 to 1500 (mPa · s, 25 ° C.), more preferably 400 to 1300 (mPa · s, 25 ° C.). The viscosity of the curing agent is preferably 30 to 3000 (mPa · s, 25 ° C.).
In the present invention, a preferable blending ratio of the main agent and the curing agent of the adhesive is main agent / curing agent = 5 to 25 in terms of mass ratio, and NCO group / OH group = 0.8 to 9 in terms of molar ratio of functional groups.

By adjusting the blending ratio within the above range, the adhesion to the adherend and the degree of crosslinking are ensured, and the tensile storage elasticity in the low temperature region at 0 ° C., frequency 10 Hz, and strain 0.1% of the adhesive layer 1. The rate can be controlled to 1.0 × 10 ⁶ to 1.0 × 10 ⁸ Pa, preferably 1.0 × 10 ⁷ to 1.0 × 10 ⁸ Pa.
The adhesive layer 1 according to the present invention preferably contains an ultraviolet absorber. Examples of ultraviolet absorbers that can be used include 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-butylphenyl) benzotriazole, 2- (2-hydroxy-5-octylphenyl) benzotriazole, 2- (3-tert-butyl-2-hydroxy-5-methylphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-amyl) Benzotriazoles such as 2-hydroxyphenyl) benzotriazole; benzophenones such as 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octyloxybenzophenone; 2- [4,6-bis (2, 4-Dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy Triazines such as phenol and 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol; Salicylates such as P-tert-butylphenyl salicylate and phenyl salicylate Among the ultraviolet absorbers, one kind or a mixture of two or more kinds can be used. The blending of the ultraviolet absorber is preferably 0.1 to 10 parts by mass, more preferably 1 to 7 parts by mass in terms of solid content with respect to 100 parts by mass of the pressure-sensitive adhesive or adhesive. If the amount is less than 0.1 parts by mass, satisfactory ultraviolet absorption performance cannot be obtained. If the amount is 10 parts by mass or more, in addition to the improvement in ultraviolet absorption performance to be obtained, adhesion performance or adhesive performance and durability are extremely reduced. .

The glass transition point of the adhesive layer 1 can be adjusted by appropriately adjusting the type or molecular weight of the adhesive or pressure-sensitive adhesive.
In the present invention, the adhesive layer 1 may be formed by directly applying a pressure-sensitive adhesive or adhesive coating liquid to the inorganic layer of the weather-resistant layer or moisture-proof layer, or applying the pressure-sensitive adhesive or adhesive. It can be formed by coating the release liquid on the release-treated surface of the release sheet that has been subjected to the release treatment, and bonding the resulting liquid to the inorganic layer of the weather-resistant layer or moisture-proof layer, and then peeling the release sheet.

As the coating liquid used for coating, it is preferable to use the above-mentioned pressure-sensitive adhesive or adhesive dissolved in an organic solvent, dissolved or dispersed in water, etc. For applications such as solar cell members that are questioned, those dissolved in an organic solvent are preferred.
Examples of the organic solvent include toluene, xylene, methanol, ethanol, isobutanol, n-butanol, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran and the like. These may be used alone or in combination of two or more.

For the convenience of coating, the coating liquid is preferably prepared using these organic solvents so that the solid content concentration is in the range of 10 to 50% by mass.
Coating of the coating liquid is, for example, conventionally known coating methods such as bar coating, roll coating, knife coating, roll knife coating, die coating, gravure coating, air doctor coating, doctor blade coating, etc. It can be done by a method.
After the coating, the adhesive layer 1 is formed by drying treatment usually at a temperature of 70 to 110 ° C. for about 1 to 5 minutes.

In the case of using an adhesive, the thickness of the adhesive layer 1 is preferably 4 μm or more, more preferably 6 μm or more from the viewpoint of obtaining a sufficient adhesive force. Moreover, from the viewpoint of preventing the moisture-proof performance from deteriorating due to an increase in stress on the inorganic layer surface of the moisture-proof layer, the thickness is preferably 12 μm or less, more preferably 10 μm or less. When using an adhesive, it is 13 micrometers or more from a viewpoint of obtaining sufficient adhesive force, Preferably it is 15 micrometers or more, More preferably, it is 20 micrometers or more. In addition, the thickness is 45 μm or less from the viewpoint of preventing the moisture-proof performance from deteriorating due to an increase in stress on the inorganic layer of the moisture-proof layer due to the structural change that occurs in the adhesive layer 1 when using high temperature and high humidity. Is preferable, and it is more preferable that it is 30 micrometers or less.

The protective material for solar cells of the present invention as described above has an interlayer strength between the weather resistant layer and the moisture-proof layer of 10 N / 15 mm or more after the condensation freezing test, and a deterioration rate of the interlayer strength from the initial interlayer strength is less than 20%. Preferably there is. The interlayer strength is more preferably 8 N / 15 mm or more.
The condensation freezing test and the deterioration rate will be described later.

In the present invention, the adhesive layer 2 and the moisture-proof layer 2 having an inorganic layer on the substrate may be further provided on the moisture-proof layer 1 in this order (moisture-proof layer 1 / adhesive layer 2 / moisture-proof layer 2). ). By having such a configuration, it is possible to further improve moisture resistance. In particular, the structure of weathering layer / adhesive layer 1 / inorganic layer / base material / adhesive layer 2 / inorganic layer / base material is preferable because moisture resistance becomes better.
The adhesive layer 2 is preferably exemplified by the same configuration as the adhesive layer 1 described above. The moisture-proof layer 2 is preferably exemplified by the same configuration as the moisture-proof layer 1 described above.
As described above, each of the films constituting the solar cell protective material of the present invention is a known additive, for example, an antistatic agent, a light blocking agent, an ultraviolet absorber, a plasticizer, a lubricant, a filler, a colorant, Stabilizers, lubricants, crosslinking agents, antiblocking agents, antioxidants and the like can be contained.
The protective material for a solar cell of the present invention is obtained by applying a pressure-sensitive adhesive or an adhesive to each film formed as described above, and drying the pressure-sensitive adhesive layer and the adhesive layer at a temperature of 70 to 140 ° C., for example. It can be manufactured by bonding together at a temperature of ° C. From the viewpoint of sufficiently bringing the pressure-sensitive adhesive layer and the adhesive layer to the degree of saturation crosslinking, the obtained laminate is preferably cured at a temperature of 30 to 80 ° C. for 1 to 7 days.
The solar cell protective material of the present invention is excellent in flexibility and moisture resistance, in which moisture resistance and interlayer strength do not deteriorate even after heat treatment under a high heat environment, that is, heat lamination conditions.
The thickness of the protective material for solar cells is not particularly limited, but is preferably 200 to 600 μm, more preferably 200 to 590 μm, more preferably 200 to 350 μm, and still more preferably 220 to 320 μm. It is used in the form of a sheet.

(Moisture resistance of solar cell protective material)
The protective material for solar cells of the present invention uses a moisture-proof film having a metal oxide layer as a substrate and a moisture permeability of less than 0.1 [g / (m ² · day)], so that the initial moisture-proof property is The transmittance is preferably 0.1 [g / (m ² · day)] or less, and more preferably 0.05 [g / (m ² · day)] or less.
The protective material for solar cell of the present invention is preferably a protective material for solar cell that is excellent in initial moisture resistance and excellent in moisture resistance and prevention of delamination even when stored in a high temperature and high humidity environment.

Further, by using the pressure-sensitive adhesive (i), its moisture resistance is determined by the degree of deterioration due to the continuous high-temperature and high-humidity environment by the vacuum lamination and the pressure coker test (120 ° C.) according to JIS C 60068-2-66. , (The water vapor transmission rate after the high-temperature and high-humidity environment / initial water vapor transmission rate) is preferably within 25, more preferably within 15 and even more preferably within 10.
The “initial moisture resistance” of the protective material for solar cells in the present invention refers to moisture resistance before the member receives a history of heat, etc. in a high temperature and high humidity environment such as vacuum lameet conditions. It means the value before sex degradation occurs. Therefore, it includes changes over time from immediately after manufacture to before high-temperature and high-humidity treatment. For example, it means a moisture-proof value in a state where heat treatment such as high temperature and high humidity environment treatment at around 100 ° C. or thermal lamination treatment performed at 130 to 180 ° C. for 10 to 40 minutes is not performed. The same applies to the “initial water vapor transmission rate”.
Each moisture-proof property in the present invention can be evaluated according to various conditions of JIS Z0222 “Method of testing moisture permeability of moisture-proof packaging container” and JIS Z0208 “Method of testing moisture permeability of moisture-proof packaging material (cup method)”.

(Interlayer strength of protective material for solar cells)
The protective material for a solar cell of the present invention comprises a pressure lamination tester according to JIS C 60068-2-66 (120 ° C.) by providing the pressure-sensitive adhesive and an intermediate film having a melting point of 150 ° C. or less on a moisture-proof film. The delamination after the continuous high heat treatment due to the above can be prevented.

(Application of protective material for solar cells)
The solar cell protective material of the present invention is particularly used for a surface protection member for a solar cell of a compound-based power generation element solar cell module or a flexible solar cell module. And the rusting of the electrode can be prevented, and the retention of the electromotive force over a long period can be achieved.

The solar cell protective material has a structure of the solar cell protective material, in particular, by laminating a fluorine-based resin film on the metal oxide layer of the moisture-proof film via the specific adhesive layer, even under high temperature conditions. Realizes solar cell protection material with excellent moisture resistance and moisture resistance, and does not deteriorate the interlayer strength over a long period of time, effectively preventing the performance of solar cells and the like from being deteriorated, and effective in improving the durability of solar cells, etc. It is possible to provide a surface protective material for a highly moisture-proof solar cell and electronic paper.
The solar cell surface protective material may be a sealing material / surface protective material integrated type formed by laminating a sealing material. By further laminating the sealing material in advance, it is possible to reduce the work of individually laminating the back surface protection sheet, the sealing material, the power generating element, the sealing material, and the front surface protection sheet in the vacuum lamination process, and the efficiency of manufacturing the solar cell module Can be achieved.

<Solar cell module, solar cell manufacturing method>
The solar cell protective material can be used as a solar cell surface protective member as it is or by being bonded to a glass plate or the like. What is necessary is just to produce by the well-known method, in order to manufacture the solar cell module and / or solar cell of this invention using the protective material for solar cells of this invention.

A solar cell module can be produced by using the solar cell protective material of the present invention in a layer structure of a surface protective member such as a solar cell front sheet or back sheet, and fixing the solar cell element together with a sealing material. . As such a solar cell module, various types can be exemplified. Preferably, when the solar cell protective material of the present invention is used as a front surface protective material, a sealing material, a solar cell element, And a solar cell module produced using a back surface protective material, specifically, a front surface protective material (protective material for solar cell of the present invention) / sealing material (sealing resin layer) / solar cell element. / Sealant (sealing resin layer) / back surface protective material, on the solar cell element formed on the inner peripheral surface of the back surface protection material and the front surface protection material (for the solar cell of the present invention) A solar cell element formed on the inner peripheral surface of a front protective material (protective material for solar cell of the present invention), for example, an amorphous solar cell on a fluororesin-based transparent protective material Sealing material on top of the device made by sputtering etc. And the like can be mentioned configuration, such as to form a surface protective material. It is optional to attach a glass plate to the outside of the solar cell protective material of the present invention as the front protective material. In addition, when using the above-mentioned sealing material / surface protective material integrated surface protective material, the above-mentioned sealing material may not be used.

Examples of solar cell elements include single crystal silicon type, polycrystalline silicon type, amorphous silicon type, gallium-arsenic, copper-indium-selenium, copper-indium-gallium-selenium, cadmium-tellurium, etc. II-VI compound semiconductor type, dye-sensitized type, organic thin film type, and the like can be mentioned.
When a solar cell module is formed using the solar cell protective material in the present invention, the moisture resistance is less than 0.1 [g / (m ² · day)] in terms of water vapor transmission rate depending on the type of the solar cell power generation element. A pressure-sensitive adhesive having a specific physical property value and thickness as described above is appropriately selected according to the element type from a low moisture-proof film of about 0.01 to a high moisture-proof film of less than 0.01 [g / (m ² · day)]. And can be formed by laminating.

The other members constituting the solar cell module produced using the solar cell protective material of the present invention are not particularly limited, but examples of the sealing material include ethylene-vinyl acetate copolymer. Coalescence can be mentioned. The back surface protection material is a single layer or multilayer sheet such as metal or various thermoplastic resin films, for example, metals such as tin, aluminum, stainless steel, inorganic materials such as glass, polyester, inorganic vapor deposition polyester, fluorine-containing resin. And a single-layer or multilayer protective material such as polyolefin. The surface of the protective material on the front surface and / or the back surface can be subjected to a known surface treatment such as a primer treatment or a corona treatment in order to improve the adhesion to the sealing material or other members.

Front surface protective material (protective material for solar cell of the present invention) / sealing material / solar cell element / sealing material / back surface protective material described above for a solar cell module produced using the solar cell protective material of the present invention An example of such a configuration will be described. The solar cell protective material, sealing material, solar cell element, sealing material, and back sheet are laminated in order from the solar light receiving side, and a junction box (from the solar cell element) is further formed on the lower surface of the back sheet. A terminal box for connecting wiring for taking out the generated electricity to the outside is bonded. The solar cell elements are connected by wiring in order to conduct the generated current to the outside. The wiring is taken out through a through hole provided in the backsheet and connected to the junction box.

As a manufacturing method of the solar cell module, a known manufacturing method can be applied and is not particularly limited, but in general, the solar cell protective material, the sealing resin layer, the solar cell element, the sealing of the present invention. It has the process of laminating | stacking a stop resin layer and a back surface protective material in order, and the process of vacuum-sucking them and carrying out thermocompression bonding. The step of vacuum suction and thermocompression bonding is, for example, a vacuum laminator, the temperature is preferably 130 to 180 ° C., more preferably 130 to 150 ° C., the degassing time is 2 to 15 minutes, and the press pressure is 0.05 to 1 MPa. The pressing time is preferably 8 to 45 minutes, more preferably 10 to 40 minutes, and heating and pressing are performed.
Also, batch type manufacturing equipment, roll-to-roll type manufacturing equipment, and the like can be applied.

The solar cell module manufactured using the solar cell protective material of the present invention is a small solar cell represented by a mobile device, a large solar cell installed on a roof or a roof, depending on the type and module shape of the applied solar cell. The battery can be applied to various uses regardless of whether it is indoors or outdoors. In particular, among electronic devices, high moisture resistance is required for use as a protective material for solar cells for flexible solar cell modules such as compound-based power generation element solar cell modules and amorphous silicon, and for use in electronic paper. Therefore, it is effectively used as a protective material for solar cells in consideration of this continuous high heat treatment. Therefore, the solar cell module manufactured using the solar cell protective material of the present invention is particularly preferably used as the surface protective material of the electronic device.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples and comparative examples. Various physical properties were measured and evaluated as follows.

[Measurement and evaluation of physical properties]
(1) Melting point of film Using a differential scanning calorimeter (Q20 manufactured by QA Instruments Co., Ltd.), according to JIS K7121, about 10 mg of sample was heated from −40 ° C. at a heating rate of 10 ° C./min. The temperature was raised to 200 ° C., the melting peak was confirmed, held at 200 ° C. for 1 minute, then cooled to −40 ° C. at a cooling rate of 10 ° C./min, and again raised to 300 ° C. at a heating rate of 10 ° C./min. The maximum peak among the crystal melting peak temperatures was determined as the melting point (Tm) [° C.] from the thermogram measured occasionally. When the melting point exceeded 200 ° C. and no melting peak was observed, such as polyester, the upper limit temperature for heating was set to 300 ° C., and then the same measurement was performed to determine the melting point.

(2) Thermal contraction rate of the film Four standard lines were drawn in parallel to the interval of 250 mm on the inside of the film cut in 15 cm square, and the distance between the standard lines was measured with a caliper. The outside of the marked line of the film was sandwiched between clips, suspended in an oven at 150 ° C., left to stand for 30 minutes, and then subjected to heat treatment.
μ = [(L1-L2) / L1] × 100
μ: Thermal contraction rate (%)
L1: Distance between marked lines of untreated film (mm)
L2: Distance between marked lines of the film after heat treatment (mm)

(3) Tensile storage modulus and glass transition point (3) -1
Each of the prepared coating liquids (B1 to 6 and 9) is applied onto a silicone release PET film, cured at 40 ° C. for 5 days, and then kept at 100 ° C. for 30 minutes to be a pressure-sensitive adhesive layer or adhesive A layer was formed. Thereafter, only the pressure-sensitive adhesive layer or adhesive layer was taken out, and a plurality of the pressure-sensitive adhesive layers or adhesive layers were stacked to prepare a sample (length 4 mm, width 60 mm, thickness 200 μm). For each of the obtained samples, using a viscoelasticity measuring device (“Viscoelastic Spectrometer DVA-200” manufactured by IT Measurement Co., Ltd.), the vibration frequency is 10 Hz, the strain is 0.1%, and the heating rate is 3 ° C./min. The stress against the strain applied to the sample was measured from −100 ° C. to 180 ° C. in the transverse direction with 25 mm between the chucks, and the tensile storage elastic modulus (Pa) at 0 ° C. and 100 ° C. was obtained from the obtained data. When the measurement at 100 ° C. is difficult due to the sample shape change at the time of temperature rise, the tensile storage elastic modulus was set to 0 Pa. Moreover, the temperature which shows a peak in the obtained loss tangent (tan-delta = loss elastic modulus / storage elastic modulus) curve was calculated | required as a glass transition point (Tg). When there are a plurality of peaks, the highest temperature is taken as the glass transition point.

(3) -2
Each of the prepared coating liquids (B10 to 13) was applied onto a silicone release PET film so as to be 25 g / m ² (the thickness after drying was 25 μm), cured at 40 ° C. for 4 days, and then 150 ° C. For 30 minutes to form a pressure-sensitive adhesive layer or an adhesive layer. Thereafter, only the pressure-sensitive adhesive layer or adhesive layer was taken out, and a plurality of the pressure-sensitive adhesive layers or adhesive layers were stacked to prepare a sample (length 4 mm, width 60 mm, thickness 200 μm). About the obtained sample, using a viscoelasticity measuring apparatus ("Viscoelastic Spectrometer DVA-200" manufactured by IT Measurement Co., Ltd.), the vibration frequency was 10 Hz, the strain was 0.1%, the temperature rising rate was 3 ° C / min, The stress against the strain applied to the sample was measured from −100 ° C. to 180 ° C. in the transverse direction with 25 mm between the chucks, and the tensile storage elastic modulus (Pa) at 0 ° C. and 100 ° C. was obtained from the obtained data. When the measurement at 100 ° C. is difficult due to the sample shape change at the time of temperature rise, the tensile storage elastic modulus was set to 0. Moreover, the temperature which shows a peak in the obtained loss tangent (tan-delta = loss elastic modulus / storage elastic modulus) curve was calculated | required as a glass transition point (Tg). When there are a plurality of peaks, the highest temperature is taken as the glass transition point.

(3) -3
Each prepared adhesive coating solution or adhesive coating solution (B14 to 16) is applied onto a silicone release PET film, cured at 40 ° C. for 5 days, and then kept at 100 ° C. for 30 minutes for adhesion. An agent layer or an adhesive layer was formed. Thereafter, only the pressure-sensitive adhesive layer or adhesive layer was taken out, and a plurality of the pressure-sensitive adhesive layers or adhesive layers were stacked to prepare a sample (length 4 mm, width 60 mm, thickness 200 μm). About the obtained sample, using a viscoelasticity measuring apparatus ("Viscoelastic Spectrometer DVA-200" manufactured by IT Measurement Co., Ltd.), the vibration frequency was 10 Hz, the strain was 0.1%, the temperature rising rate was 3 ° C / min, The stress against the strain applied to the sample was measured from −100 ° C. to 100 ° C. in the transverse direction with a chuck spacing of 25 mm, and the tensile storage elastic modulus (Pa) at 0 ° C. and 100 ° C. was obtained from the obtained data. Moreover, the temperature which shows a peak in the obtained loss tangent (tan-delta = loss elastic modulus / storage elastic modulus) curve was calculated | required as a glass transition point (Tg). When there are a plurality of peaks, the highest temperature is taken as the glass transition point.

(4) Pressure cooker (PC) test (4) -1
Each of the solar cell protective materials (F-1-1 to F-1-18) was cut into 150 mm × 150 mm squares, and this was used as a surface protective material. Glass, sealing material, surface protective material (fluorine resin film Layered in the order of the sealing material side and the other side), using a vacuum laminator (manufactured by NPC, “LM30 × 30”), 140 ° C., 15 minutes, pressure 0.1 MPa Vacuum lamination was performed under the conditions of: Next, a pressure cooker test was performed using a pressure cooker test LSK-500 manufactured by Tommy Seiko Co., Ltd. under the test (PC 24-1) conditions of 120 ° C., 100% humidity, and 24 hours.

(4) -2
Each of the solar cell protective materials (F-2-1 to F-2-14) was cut into 150 mm × 150 mm squares, and this was used as a surface protective material. Glass, sealing material, surface protective material (fluorine resin film Layered in the order of the sealing material side and the other side), and using a vacuum laminator (manufactured by NPC Corporation, “LM30 × 30”), 150 ° C., 11 minutes, pressure 0.1 MPa Vacuum lamination was performed under the conditions of: Next, a pressure cooker test was performed using a pressure cooker test LSK-500 manufactured by Tommy Seiko Co., Ltd. under the test (PC 24-2) conditions of 120 ° C., 100% humidity, and 24 hours.

(4) -3
Each of the solar cell protective materials (F-3-1 to F-3-8) was cut into 150 mm × 150 mm squares, and this was used as a surface protective material. Glass, sealing material, surface protective material (fluorine resin film Layered in the order of the sealing material side and the other side), and using a vacuum laminator (manufactured by NPC, “LM30 × 30”), 150 ° C., 15 minutes, pressure 0.1 MPa Vacuum lamination was performed under the conditions of: Next, using a pressure cooker test (Tomy Seiko Co., Ltd., “LSK-500”), a pressure cooker test was conducted under the test (PC48) conditions of 105 ° C., 100% humidity and 48 hours.

(5) Pressure cooker delamination test Each solar cell protective material (F-3-1 to F-3-8) was cut into 150 mm × 150 mm squares, and this was used as a surface protective material to make glass, sealing material, Laminate so that the surface protective material (the fluororesin film is opposite to the sealing material side) in this order, and use a vacuum laminator (manufactured by NPC, "LM30x30") to 150 Vacuum lamination was performed under the conditions of ° C, 15 minutes, and pressure of 0.1 MPa. Next, using a pressure cooker test (Tomy Seiko Co., Ltd., “LSK-500”), a pressure cooker test is performed at 105 ° C. and a humidity of 100%, and the occurrence of delamination is visually observed at the end face of the surface protective material. The test time until it can be confirmed was measured. Those in which the occurrence of delamination could not be confirmed in 90 hours were over 90 hours (> 90).

(6) Condensation freezing test (HF)
Each of the solar cell protective materials (F-4-1 to F-4-6) is cut into 150 mm × 150 mm squares, and this is used as a surface protective material. Glass, sealing material, surface protective material (fluorine resin film Layered in the order of the sealant side and the other side), using a vacuum laminator (manufactured by NPC, "LM30x30") at 150 ° C for 11 minutes, pressure 0.1 MPa A sample was prepared by vacuum lamination under the following conditions.
Using a method in accordance with JIS C 8990-2004, a sample is held for 20 hours in an environment of 85 ° C. and 85% relative humidity using an ultra-low temperature and humidity chamber (manufactured by ESPEC Corporation, “PSL-2KPH”). Then, the temperature is set to −40 ° C. over 1.5 hours, and the sample is held for 1 hour in the temperature −40 ° C. environment. The cycle was repeated 20 times.

(7) Dump heat test (DH)
Each of the solar cell protective materials (F-4-1 to F-4-6) is cut into 150 mm × 150 mm squares, and this is used as a surface protective material. Glass, sealing material, surface protective material (fluorine resin film Layered in the order of the sealant side and the other side), using a vacuum laminator (manufactured by NPC, "LM30x30") at 150 ° C for 11 minutes, pressure 0.1 MPa A sample was prepared by vacuum lamination under the following conditions.
Using a method in accordance with JIS C 60068-3-4, a sample is held for 400 hours at 85 ° C. and 85% relative humidity using a thermo-hygrostat (trade name: PH-3KT, manufactured by ESPEC Corporation). did.

(8) Appearance (8) -1: Appearance after vacuum lamination Protective materials for solar cells (F-1-1 to F-1-18, F-2-1 to F-2-14) are 150 mm x 150 mm Cut out into corners, use this as a surface protective material, and laminate it in the order of glass, sealing material, surface protective material (fluorine resin film opposite to the sealing material side), and vacuum laminator (Co., Ltd. ) Made by NPC, “LM30 × 30”) at 140 ° C., 15 minutes, pressure 0.1 MPa (F-1-1 to F-1-18) or 150 ° C., 11 minutes, pressure Vacuum lamination was performed under conditions of 0.1 MPa (F-2-1 to F-2-14) to prepare samples. The appearance of the obtained sample was observed and evaluated according to the following evaluation criteria.
◯: A good solar cell module without wrinkles on the surface protective material surface can be obtained.
X: Wrinkles are observed on the surface protective material surface.

(8) -2: Appearance after condensation freeze test or dump heat test Protective materials for solar cells (F-4-1 to F-4-6) visually confirmed after condensation freeze test or dump heat test And evaluated according to the following evaluation criteria.
○: No change compared to the initial state.
X: The adhesive layer is whitened compared with the initial state.

(9) Interlayer strength and interlayer strength deterioration rate (9) -1: Interlayer strength Protective materials for solar cells (F-1-1 to F-1-18, F-2-1 to F-2-14) Cut into strips with a measurement width of 15 mm, using a tensile testing machine ("STA-1150" manufactured by ORIENTIC Co., Ltd.) at 300 mm / min, with a tensile direction of 180 degrees, and the interlayer strength between the fluororesin film and the moisture-proof film (N / 15 mm) was measured and evaluated according to the following evaluation criteria.
○: Interlayer strength is 5 N / 15 mm or more.
X: The interlayer strength is less than 5 N / 15 mm.

(9) -2: Interlayer strength and interlayer strength deterioration rate Each solar cell protective material (F-4-1 to F-4-6) was cut into a strip shape with a measurement width of 15 mm, and a tensile tester (made by ORIENTIC, “ STA-1150 ") at 300 mm / min, the tensile direction is 180 degrees, and the interlaminar strength (N / 15 mm) between the fluororesin film and the moisture-proof film 1 (first moisture-proof film as seen from the fluororesin film side) ) Was measured.
The measurement was performed immediately after the production of the solar cell protective material, after the condensation freezing test, and after the dump heat test.
Also, how much the interlayer strength after the condensation freezing test or the dump heat test has deteriorated relative to the interlayer strength (initial interlayer strength) after the solar cell protective material is produced is expressed by the following formula as the interlayer strength deterioration rate (%) Determined by
Interlayer strength deterioration rate (%) = [1− (interlayer strength of solar cell protective material after condensation freeze test or dump heat test) / (initial interlaminar strength of solar cell protective material)] × 100

(10) Moisture resistance at the end face Each solar cell protective material (F-1-1 to F-1-18) is cut into a 150 mm × 150 mm square, and this is used as a surface protective material to make glass, a sealing material, and a surface protective material. Laminate so that the fluororesin film is in the order opposite to the sealing material side, and then place green cobalt chloride paper of 1 cm on each side at a position 2 cm from the center of the glass and at the center of the glass. As described above, sandwiched between a sealing material and a surface protective material, using a vacuum laminator (manufactured by NPC Corporation, “LM30 × 30”) at 140 ° C., 15 minutes, pressure 0.1 MPa A vacuum laminate was performed to prepare a sample. The obtained sample was subjected to a pressure cooker test under the test conditions of 120 ° C., 100% humidity, and 24 hours by a pressure cooker test (Tomy Seiko Co., Ltd., “LSK-500”). The appearance after the pressure cooker test was observed and evaluated according to the following evaluation criteria.
◯: The color of the cobalt chloride paper at the center of the glass and the cobalt chloride paper at a position 2 cm from the edge remains green.
X: The cobalt chloride paper at the center of the glass remained green, but the cobalt chloride paper at a position 2 cm from the end turns red. Or both cobalt chloride papers turn red.

(11) Moisture resistance The moisture resistance of the resin films having the metal oxide layer (moisture-proof films C-1 to C-4) is determined according to JIS Z 0222 “ In accordance with the conditions of “moisture-proof packaging container moisture permeability test method” and JIS Z 0208 “moisture-proof packaging material moisture permeability test method (cup method)”, the water vapor permeability was determined and evaluated by the following method. Further, the moisture resistance of the solar cell protective material is determined immediately after the production of the solar cell protective material (F-1-1 to F-1-18, F-2-1 to F-2-14, F-3-1 to F-3-8, F-4-1 to F-4-6), after pressure cooker test (PC24-1) (F-1-1 to F-1-18), pressure cooker test (PC24-2) After (F-2-1 to F-2-14), after pressure cooker test (P48) (F-3-1 to F-3-8), after condensation freezing test and after dump heat test (F-4- 1 to F-4-6) were evaluated in the same manner as described above. The water vapor transmission rate immediately after the production of the solar cell protective material was taken as the initial water vapor transmission rate.

(Calculation of water vapor transmission rate)
Using each of the following samples of a moisture permeable area 10.0 cm × 10.0 cm square, making a stretched polypropylene film inside, producing a bag containing about 20 g of anhydrous calcium chloride as a hygroscopic agent and sealing four sides, The bag is put into a constant temperature and humidity device at a temperature of 40 ° C. and a relative humidity of 90%, and the mass is measured until about 200 days at intervals of 72 hours or more. From the slope of the regression line between the elapsed time after the fourth day and the bag mass. The water vapor transmission rate [g / (m ² · day)] at a temperature of 40 ° C. and a relative humidity of 90% was calculated.

(sample)
Sample using moisture-proof film: urethane adhesive (AD900 and CAT-RT85 manufactured by Toyo Morton Co., Ltd. 10: 1.5) on the surface of a stretched polypropylene film (P1146 manufactured by Toyobo Co., Ltd.) having a thickness of 60 μm The mixture was applied and dried to form an adhesive layer having a thickness of about 3 μm. On the adhesive layer, the metal oxide layer surface side of the moisture-proof film (C1 to C4) after production and storage at 40 ° C. for one week was laminated to obtain a sample.

Sample using a protective material for solar cell: urethane adhesive (AD900 and CAT-RT85 manufactured by Toyo Morton Co., Ltd. 10: 1) on the surface of a stretched polypropylene film (P1146 manufactured by Toyobo Co., Ltd.) having a thickness of 60 μm. 5) was applied and dried to form an adhesive layer having a thickness of about 3 μm. The substrate surface side of each solar cell protective material was laminated on this adhesive layer to obtain a sample.

(12) Deterioration degree of moisture resistance (water vapor transmission rate) Using the water vapor transmission rate obtained in (11), the deterioration degree of moisture resistance was determined by the following equation.
Degree of moisture proof deterioration = (water vapor transmission rate of solar cell protective material after each test) / (initial water vapor transmission rate of solar cell protective material)
The solar cell protective materials F-1-1 to F-1-18 and F-2-1 to F-2-14 were evaluated according to the following evaluation criteria.
○: The water vapor transmission rate after the test is less than 3 times the initial water vapor transmission rate of the solar cell protective material.
X: The water vapor transmission rate after a test is 3 times or more with respect to the initial water vapor transmission rate of the protective material for solar cells.

[Constituent materials]
<Fluorine resin film>
(Fluorine resin film A-1)
As the fluororesin film A-1, a tetrafluoroethylene-ethylene copolymer (ETFE) film (manufactured by Asahi Glass Co., Ltd., trade name: Aflex 50MW1250DCS, thickness 50 μm) was used.

<Coating fluid>
(Adhesive coating liquid B-1)
Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, and the air in the reaction apparatus was replaced with nitrogen gas. Thereafter, in this reactor, butyl acrylate and methyl acrylate as main monomers were reacted at 60 ° C. for 8 hours to obtain a solution of an acrylic copolymer having a weight average molecular weight of 800,000 having a hydroxyl group introduced as a functional group. . The resulting acrylic copolymer solution was blended with an isocyanate crosslinking agent and a benzotriazole ultraviolet absorber to prepare an adhesive coating solution B-1.

(Adhesive coating solution B-2)
A pressure-sensitive adhesive coating solution B-2 was prepared in the same manner as in the production of the pressure-sensitive adhesive coating solution B-1, except that the weight average molecular weight of the acrylic copolymer was adjusted to 500,000.

(Adhesive coating solution B-3)
A pressure-sensitive adhesive coating solution B-3 was prepared in the same manner as in the production of the pressure-sensitive adhesive coating solution B-1, except that a carboxyl group was introduced as a functional group of the acrylic copolymer.

(Adhesive coating solution B-4)
A pressure-sensitive adhesive coating solution B-4 was prepared in the same manner as in the production of the pressure-sensitive adhesive coating solution B-1, except that an amino group was introduced as a functional group of the acrylic copolymer.

(Adhesive coating solution B-5)
A pressure-sensitive adhesive coating solution B-5 was prepared in the same manner as in the production of the pressure-sensitive adhesive coating solution B-1, except that the weight average molecular weight of the acrylic copolymer was adjusted to 100,000.

(Adhesive coating solution B-6)
As a main ingredient containing a polyester polyol component, A1143 (trade name, molecular weight per ester group is 109, viscosity is 500 [mPa · s]) manufactured by Mitsui Chemicals Polyurethane Co., Ltd. is used. Takenate A-50 (trade name) manufactured by Mitsui Chemicals, Inc. is used as a curing agent containing diisocyanate and aromatic xylylene diisocyanate, and mixed so that the mass ratio of the main agent / curing agent is 9/1. Then, an adhesive coating solution B-6 was prepared by diluting with ethyl acetate so that the solid content concentration was 35% by mass.

(Adhesive coating solution B-7)
A pressure-sensitive adhesive coating solution B-7 was prepared in the same manner as B-1, except that no benzotriazole ultraviolet absorber was added.

(Adhesive coating liquid B-8)
Adhesive coating solution B-8 was prepared in the same manner as B-2, except that no benzotriazole ultraviolet absorber was added.

(Adhesive coating solution B-9)
As a main component containing a polycarbonate polyol component, a polycaprolactone polyol having an average molecular weight of 2000 (trade name “Placcel 210N” manufactured by Daicel Chemical Industries, Ltd.) and a polycarbonate diol having an average molecular weight of 500 (trade name “manufactured by Daicel Chemical Industries, Ltd.”) Plaxel CD CD205 "), and mixed so that the mass ratio of polycaprolactone polyol / polycarbonate diol is 60/40, dissolved in ethyl acetate, and has a solid content of about 50 mass% and a viscosity of 400 [mPa · s]. A polyol solution was obtained. In this polyol solution, Sumidur N3300 (manufactured by Sumika Bayer Urethane Co., Ltd.) was blended as a curing component so that the mass ratio was 10 / 0.5, and acetic acid was added so that the solid content concentration was 35% by mass. Diluted with ethyl to prepare adhesive coating solution B-9.

(Adhesive coating solution B-10)
Using a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube, a mixed solution of 90 parts by mass of butyl acrylate, 10 parts by mass of acrylic acid, 75 parts by mass of ethyl acetate, and 75 parts by mass of toluene, 0.3 parts by mass of azobisisobutyronitrile was added, and polymerization was performed at 80 ° C. for 8 hours in a nitrogen gas atmosphere. After completion of the reaction, the solid content was adjusted to 30% by mass with toluene to obtain a resin having a mass average molecular weight of 500,000. To 100 parts by mass of the obtained resin, 1 part by mass of Coronate L (trade name: Nippon Polyurethane Industry Co., Ltd., solid content: 75% by mass) is added as an isocyanate-based cross-linking agent, and pressure-sensitive adhesive coating solution B- 10 was prepared.

(Adhesive coating solution B-11)
Using a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas inlet tube, 70 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of methyl acrylate, 5 parts by mass of acrylic acid, 20 parts by mass of ethyl acetate, 0.3 parts by mass of azobisisobutyronitrile was added to a mixed solution of 20 parts by mass of toluene, and polymerization was performed at 80 ° C. for 8 hours in a nitrogen gas atmosphere. After completion of the reaction, the solid content was adjusted to 30% by mass with toluene to obtain a resin having a mass average molecular weight of 500,000. To 100 parts by mass of the obtained resin, 1 part by mass of Coronate L (trade name: Nippon Polyurethane Industry Co., Ltd., solid content: 75% by mass) is added as an isocyanate-based cross-linking agent, and pressure-sensitive adhesive coating solution B- 11 was prepared.

(Adhesive coating liquid B-12)
Using a reactor equipped with a thermometer, stirrer, reflux condenser, and nitrogen gas inlet tube, 40 parts by mass of butyl acrylate, 10 parts by mass of isobutyl acrylate, 40 parts by mass of methyl acrylate, 10 parts by mass of acrylic acid, acetic acid 0.3 parts by mass of azobisisobutyronitrile was added to a mixed solution of 75 parts by mass of ethyl and 75 parts by mass of toluene, and polymerization was performed at 80 ° C. for 8 hours in a nitrogen gas atmosphere. After completion of the reaction, the solid content was adjusted to 30% by mass with toluene to obtain a resin having a mass average molecular weight of 500,000. To 100 parts by mass of the obtained resin, 1 part by mass of Coronate L (trade name: Nippon Polyurethane Industry Co., Ltd., solid content: 75% by mass) is added as an isocyanate-based cross-linking agent, and pressure-sensitive adhesive coating solution B- 12 was prepared.

(Adhesive coating solution B-13)
HD1013 manufactured by Rock Paint Co., Ltd. is used as the main agent containing the polyurethane polyol component, and H62 manufactured by Rock Paint Co., Ltd. is used as the curing agent containing the aliphatic hexamethylene diisocyanate component, resulting in a weight ratio of 10: 1. Were mixed with each other and diluted with ethyl acetate so that the solid content concentration was 30% by mass to prepare an adhesive coating solution B-13.

(Adhesive coating liquid B-14)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser, n-butyl acrylate 60 parts by weight, methyl acrylate 40 parts by weight, 4-hydroxybutyl acrylate 5 parts by weight, a polymerization initiator Then, 0.1 part by weight of 2,2-azobisisobutyronitrile and 200 parts by weight of ethyl acetate were added, and the atmosphere was purged with nitrogen for 1 hour, and then kept at around 60 ° C. while stirring in a nitrogen stream for 9 hours. A polymerization reaction was performed to prepare an acrylic polymer solution (1) having a weight average molecular weight of 300,000. Uniformity of 0.2 parts by weight of isocyanate cross-linking agent (hexamethylene diisocyanate adduct of trimethylolpropane; manufactured by Mitsui Takeda Chemical Co., D-160N) as a cross-linking agent with respect to 100 parts by weight of solid content of polymer solution (1) The mixture was mixed and stirred to prepare an adhesive coating solution B-14.

(Adhesive coating solution B-15)
In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, n-butyl acrylate 100 parts by weight, acrylic acid 3 parts by weight, 4-hydroxybutyl acrylate 2 parts by weight, as a polymerization initiator Then, 0.1 part by weight of 2,2-azobisisobutyronitrile and 200 parts by weight of ethyl acetate were added, and the atmosphere was purged with nitrogen for 1 hour, and then kept at around 60 ° C. for 9 hours while stirring under a nitrogen stream. Reaction was performed to prepare an acrylic polymer solution (2) having a weight average molecular weight of 400,000. Uniformly 0.2 parts by weight of an isocyanate crosslinking agent (hexamethylene diisocyanate adduct of trimethylolpropane; manufactured by Mitsui Takeda Chemical Co., D-160N) as a crosslinking agent with respect to 100 parts by weight of the solid content of the polymer solution (2) The mixture was mixed and stirred to prepare an adhesive coating solution B-15.

(Adhesive coating solution B-16)
IS801 manufactured by Toyo Ink Mfg. Co., Ltd. (molecular weight per ester group: 105, viscosity 1700 [mPa · sec]) is used as the main component containing the polyester polyol component, and Toyo is used as the curing agent containing the hexamethylene diisocyanate component and isophorone diisocyanate. Using CR001 manufactured by Ink Manufacturing Co., Ltd., mixing at a mass ratio of 10: 1, diluting with ethyl acetate to a solid content concentration of 30% by mass, and then applying the adhesive coating solution B-16 Prepared. The glass transition point (Tg) of the adhesive layer comprising the adhesive coating solution 2 was 32 ° C.

Tables 1 to 3 show the tensile storage elastic modulus and glass transition point of the pressure-sensitive adhesive layer or adhesive layer formed using each coating solution.

<Resin film having metal oxide layer (moisture-proof film)>
(Dampproof film C-1)
A biaxially stretched polyethylene naphthalate film (made by Teijin DuPont Films Co., Ltd., trade name: “Q51C”) having a thickness of 12 μm was used as a substrate, and the following coating solution was applied to the corona-treated surface and dried to obtain a thickness of 0. A 1 μm coat layer was formed.
Next, SiO was heated and evaporated under a vacuum of 1.33 × 10 ⁻³ Pa (1 × 10 ⁻⁵ Torr) using a vacuum deposition apparatus, and SiOx (x = 1.5) having a thickness of 50 nm was formed on the coating layer. A resin film C-1 having a metal oxide layer was obtained. The moisture-proof film C-1 produced had a moisture-proof property of 0.01 [g / (m ² · day)].

(Coating solution)
An aqueous solution obtained by adding 220 g of polyvinyl alcohol resin (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name: “GOHSENOL”, degree of saponification: 97.0 to 98.8 mol%, degree of polymerization: 2400) to 2810 g of ion-exchanged water and dissolving by heating. To the mixture, 645 g of 35 mol% hydrochloric acid was added while stirring at 20 ° C. Subsequently, 3.6 g of butyraldehyde was added with stirring at 10 ° C., and after 5 minutes, 143 g of acetaldehyde was added dropwise with stirring to precipitate resin fine particles. Subsequently, after hold | maintaining at 60 degreeC for 2 hours, the liquid was cooled, neutralized with sodium hydrogencarbonate, washed with water, and dried, and the polyvinyl acetoacetal resin powder (acetalization degree 75 mol%) was obtained.
Further, an isocyanate resin (manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name: “Sumidule N-3200”) was used as a crosslinking agent, and the mixture was mixed so that the equivalent ratio of isocyanate groups to hydroxyl groups was 1: 2.

(Dampproof film C-2)
The same moisture-proof film except that the base material was changed to a biaxially stretched polyethylene naphthalate film with a thickness of 25 μm (manufactured by Teijin DuPont Films, Inc., trade name: “Q51C”) in the production of the moisture-proof film C-1. C-2 was produced. The produced moisture-proof film C-2 had a moisture-proof property of 0.01 [g / (m ² · day)].

(Moisture-proof film C-3)
The same moisture-proof film except that the base material was changed to a 50 μm-thick biaxially stretched polyethylene naphthalate film (manufactured by Teijin DuPont Films, trade name: “Q51C”) in the production of the moisture-proof film C-1. C-3 was produced. The produced moisture-proof film C-3 had a moisture-proof property of 0.01 [g / (m ² · day)].

(Moisture-proof film C-4)
A tech barrier LX made by Mitsubishi Plastics in which silica was vapor-deposited on a polyethylene terephthalate resin film having a thickness of 12 μm was used as the moisture-proof film C-4. The produced moisture-proof film C-4 had a moisture-proof property of 0.2 [g / (m ² · day)].

<High melting point film>
(High melting point film D-1)
A polyethylene terephthalate film (Mitsubishi Resin Co., Ltd., trade name: Diafoil T-100, thickness: 50 μm) is passed through a drying furnace with a furnace length of 27 m and a temperature of 170 ° C. at a rate of 50 meters / minute and heat-treated to have a high melting point. Film D-1 was produced. The high melting point film D-1 had a thermal shrinkage of 0.3% and a melting point of 252 ° C.

(High melting point film D-2)
A polyethylene terephthalate film (manufactured by Mitsubishi Plastics, trade name: Diafoil T-100, thickness: 50 μm) was used as the high melting point film D-2. The high melting point film D-2 had a heat shrinkage rate of 1.2% and a melting point of 252 ° C.

(Intermediate film)
E-1: An ethylene-vinyl acetate sealing material (trade name: EVASKY S11 (thickness: 500 μm, melting point: 69.6 ° C.)) manufactured by Bridgestone Corporation was used as an intermediate film.

E-2: Add necessary additives to low density polyethylene resin, knead well to prepare low density polyethylene resin, and then extrude the low density polyethylene resin with an extruder, unstretched with a thickness of 140 μm An intermediate film made of low density polyethylene resin was produced. The melting point was 109 ° C.

E-3: Layer thickness ratio of homopolypropylene resin composition and ethylene-propylene random copolymer resin with an extruder 0.1: 0.8: 0.1 (homopolypropylene resin layer is the central layer, ethylene-propylene random A copolymer resin was multilayer extruded with both outer layers) to produce a 190 μm thick unstretched polypropylene resin film, which was used as an intermediate film. The melting point measured by the above method was 162.3 ° C.

<Encapsulant>
As the sealing material, ethylene-vinyl acetate copolymer (EVA) (manufactured by Bridgestone Corporation, trade name: EVASKY S11, thickness: 500 μm) was used.

<Glass>
White plate glass having a length of 150 mm, a width of 150 mm, and a thickness of 3 mm was used.

Example 1-1
The adhesive coating liquid B-1 was applied to the fluororesin film A-1 and dried so as to have a solid content of 20 g / m ^2, and the 20 μm-thick adhesive layer (i) surface and metal of the moisture-proof film C-1 were produced. The oxide layer surface was bonded, and then cured at 40 ° C. for 5 days to produce a solar cell protective material F-1-1 having a thickness of 82 μm. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-1. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-1 was 0.01 [g / (m ² · day)].

Example 1-2
A solar cell protective material F-1-2 having a thickness of 92 μm was obtained in the same manner as in Example 1-1 except that the coating amount of the pressure-sensitive adhesive coating solution B-1 was changed to a solid content of 30 g / m ^2. Was made. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-2. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-2 was 0.01 [g / (m ² · day)].

Example 1-3
A solar cell protective material F-1-3 having a thickness of 95 μm was produced in the same manner as in Example 1-1, except that the moisture-proof film C-1 was changed to the moisture-proof film C-2. Using the obtained solar cell protective material F-1-3, various measurements and evaluations were performed. The results are shown in Table 4. The initial water vapor permeability of the protective material F-1-3 for solar cells was 0.01 [g / (m ² · day)].

Example 1-4
A solar cell protective material F-1-4 having a thickness of 105 μm was obtained in the same manner as in Example 1-3, except that the coating amount of the adhesive coating solution B-1 was changed to a solid content of 30 g / m ^2. Was made. Using the obtained solar cell protective material F-1-4, various measurements and evaluations were performed. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-4 was 0.01 [g / (m ² · day)].

Example 1-5
A solar cell protective material F-1-5 having a thickness of 82 μm was produced in the same manner as in Example 1-1 except that the adhesive coating liquid B-1 was changed to the adhesive coating liquid B-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-5. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-5 was 0.01 [g / (m ² · day)].

Example 1-6
A solar cell protective material F-1-6 having a thickness of 92 μm was produced in the same manner as in Example 1-2 except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-6. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-6 was 0.01 [g / (m ² · day)].

Example 1-7
A solar cell protective material F-1-7 having a thickness of 95 μm was produced in the same manner as in Example 1-3, except that the adhesive coating liquid B-1 was changed to the adhesive coating liquid B-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-7. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-7 was 0.01 [g / (m ² · day)].

Example 1-8
A solar cell protective material F-1-8 having a thickness of 105 μm was produced in the same manner as in Example 1-4, except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-8. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-8 was 0.01 [g / (m ² · day)].

Comparative Example 1-1
A solar cell protective material F-1-9 having a thickness of 82 μm was produced in the same manner as in Example 1-1 except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-3. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-9. The results are shown in Table 4. The initial water vapor transmission rate of the solar cell protective material F-1-9 was 0.01 [g / (m ² · day)].

Comparative Example 1-2
A solar cell protective material F-1-10 having a thickness of 92 μm was obtained in the same manner as in Comparative Example 1-1 except that the coating amount of the adhesive coating solution B-3 was changed to a solid content of 30 g / m ^2. Was made. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-10. The results are shown in Table 4. The initial water vapor transmission rate of the solar cell protective material F-1-10 was 0.01 [g / (m ² · day)].

Comparative Example 1-3
A solar cell protective material F-1-11 having a thickness of 82 μm was produced in the same manner as in Example 1-1 except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-4. Using the obtained solar cell protective material F-1-11, various measurements and evaluations were performed. The results are shown in Table 4. The initial water vapor transmission rate of the solar cell protective material F-1-11 was 0.01 [g / (m ² · day)].

Comparative Example 1-4
A solar cell protective material F-1-12 having a thickness of 92 μm was obtained in the same manner as in Comparative Example 1-3, except that the coating amount of the adhesive coating solution B-4 was changed to a solid content of 30 g / m ^2. Was made. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-12. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-12 was 0.01 [g / (m ² · day)].

Comparative Example 1-5
A solar cell protective material F-1-13 having a thickness of 82 μm was produced in the same manner as in Example 1-1 except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-5. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-13. The results are shown in Table 4. The initial water vapor transmission rate of the solar cell protective material F-1-13 was 0.01 [g / (m ² · day)].

Comparative Example 1-6
A solar cell protective material F-1-14 having a thickness of 112 μm was obtained in the same manner as in Example 1-1 except that the coating amount of the adhesive coating solution B-1 was changed to a solid content of 50 g / m ^2. Was made. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-14. The results are shown in Table 4. The initial water vapor transmission rate of the solar cell protective material F-1-14 was 0.01 [g / (m ² · day)].

Comparative Example 1-7
A solar cell protective material F-1-15 having a thickness of 112 μm was produced in the same manner as in Comparative Example 1-6, except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-15. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-15 was 0.01 [g / (m ² · day)].

Comparative Example 1-8
A solar cell protective material F-1-16 having a thickness of 120 μm was produced in the same manner as in Example 1-1 except that the moisture-proof film C-1 was changed to the moisture-proof film C-3. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-16. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-16 was 0.01 [g / (m ² · day)].

Comparative Example 1-9
A solar cell protective material F-1-17 having a thickness of 120 μm was produced in the same manner as in Comparative Example 1-8, except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-17. The results are shown in Table 4. The initial water vapor permeability of the solar cell protective material F-1-17 was 0.01 [g / (m ² · day)].

Comparative Example 1-10
The thickness was changed in the same manner as in Example 1-1 except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-6 and the coating amount was changed to a solid content of 8 g / m ^2. A protective material F-1-18 for a solar cell of 70 μm was produced. Various measurements and evaluations were performed using the obtained solar cell protective material F-1-18. The results are shown in Table 4. The initial water vapor transmission rate of the solar cell protective material F-1-18 was 0.01 [g / (m ² · day)].

As apparent from Table 4, the thickness of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer at 100 ° C., the frequency of 10 Hz, the tensile storage elastic modulus at a strain of 0.1%, and the substrate thickness of the moisture-proof film are within the specified range of the present invention. The protective materials for solar cells of Comparative Examples 1-1 to 10, which were outside, were inferior in end face moisture resistance. Moreover, it was inferior to moisture resistance and / or interlayer strength.
On the other hand, the solar cell protective materials of Examples 1-1 to 8 are all excellent in appearance, and excellent in interlayer strength and moisture resistance, particularly in end face moisture resistance.

Example 2-1
The adhesive coating liquid B-1 was applied to the fluororesin film A-1 and dried so as to have a solid content of 20 g / m ^2, and the 20 μm-thick adhesive layer (i) surface and metal of the moisture-proof film C-1 were produced. The oxide layer surface was bonded, and the adhesive coating solution B-7 was applied and dried on the opposite surface of the metal oxide layer surface of the moisture-proof film C-1 to a solid content of 20 g / m ^2. The surface of the adhesive layer (ii) and the high melting point film D-1 were bonded. Thereafter, it was cured at 40 ° C. for 5 days to produce a solar cell protective material F-2-1 having a thickness of 152 μm. Using the obtained solar cell protective material F-2-1, various measurements and evaluations were performed. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-1 was 0.01 [g / (m ² · day)].

Example 2-2
A solar cell protective material F-2-2 having a thickness of 152 μm was produced in the same manner as in Example 2-1, except that the pressure-sensitive adhesive coating liquid B-1 was changed to the pressure-sensitive adhesive coating liquid B-2. Using the obtained solar cell protective material F-2-2, various measurements and evaluations were performed. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-2 was 0.01 [g / (m ² · day)].

Example 2-3
A solar cell protective material F-2-3 having a thickness of 165 μm was produced in the same manner as in Example 2-1, except that the moisture-proof film C-1 was changed to the moisture-proof film C-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-3. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-3 was 0.01 [g / (m ² · day)].

Example 2-4
A solar cell protective material F-2-4 having a thickness of 165 μm was produced in the same manner as in Example 2-3 except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-4. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-4 was 0.01 [g / (m ² · day)].

Example 2-5
In the same manner as in Example 2-1, except that the pressure-sensitive adhesive coating liquid B-7 was changed to pressure-sensitive adhesive coating liquid B-8, and the coating amount was changed to a solid content of 8 g / m ^2. A protective material F-2-5 for solar cells of 140 μm was produced. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-5. The results are shown in Table 5. The initial water vapor transmission rate of the solar cell protective material F-2-5 was 0.01 [g / (m ² · day)].

Comparative Example 2-1
A solar cell protective material F-2-6 having a thickness of 182 μm was obtained in the same manner as in Example 2-1, except that the coating amount of the adhesive coating solution B-1 was changed to a solid content of 50 g / m ^2. Was made. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-6. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-6 was 0.01 [g / (m ² · day)].

Comparative Example 2-2
A solar cell protective material F-2-7 having a thickness of 195 μm was produced in the same manner as in Comparative Example 2-1, except that the moisture-proof film C-1 was changed to the moisture-proof film C-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-7. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-7 was 0.01 [g / (m ² · day)].

Comparative Example 2-3
A solar cell protective material F-2-8 having a thickness of 152 μm was produced in the same manner as in Example 2-1, except that the adhesive coating liquid B-1 was changed to the adhesive coating liquid B-3. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-8. The results are shown in Table 5. The initial water vapor transmission rate of the solar cell protective material F-2-8 was 0.01 [g / (m ² · day)].

Comparative Example 2-4
A solar cell protective material F-2-9 having a thickness of 152 μm was produced in the same manner as in Example 2-1, except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-4. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-9. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-9 was 0.01 [g / (m ² · day)].

Comparative Example 2-5
A solar cell protective material F-2-10 having a thickness of 152 μm was produced in the same manner as in Example 2-1, except that the adhesive coating liquid B-1 was changed to the adhesive coating liquid B-5. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-10. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-10 was 0.01 [g / (m ² · day)].

Comparative Example 2-6
A solar cell protective material F-2-11 having a thickness of 152 μm was produced in the same manner as in Example 2-1, except that the high melting point film D-1 was changed to the high melting point film D-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-11. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-11 was 0.01 [g / (m ² · day)].

Comparative Example 2-7
A solar cell protective material F-2-12 having a thickness of 152 μm was produced in the same manner as in Comparative Example 2-6, except that the adhesive coating solution B-1 was changed to the adhesive coating solution B-2. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-12. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-12 was 0.01 [g / (m ² · day)].

Comparative Example 2-8
A solar cell protective material F-2-13 having a thickness of 190 μm was produced in the same manner as in Example 2-1, except that the moisture-proof film C-1 was changed to the moisture-proof film C-3. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-13. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-13 was 0.01 [g / (m ² · day)].

Comparative Example 2-9
The adhesive coating liquid B-1 was changed to the adhesive coating liquid B-6, the coating amount was changed to a solid content of 8 g / m ² , and the adhesive coating liquid B-7 was changed to the adhesive coating liquid B. A solar cell protective material F-2-14 having a thickness of 128 μm was produced in the same manner as in Example 2-1, except that the coating amount was changed to −9 and the coating amount was changed to 8 g / m ^{2 in} solid content. Various measurements and evaluations were performed using the obtained solar cell protective material F-2-14. The results are shown in Table 5. The initial water vapor permeability of the solar cell protective material F-2-14 was 0.01 [g / (m ² · day)].

As is apparent from Table 5, the thickness of the pressure-sensitive adhesive layer (i), the tensile strength of the pressure-sensitive adhesive layer (i) at 100 ° C., the frequency of 10 Hz, and the strain of 0.1%, the substrate thickness of the moisture-proof film, and the high melting point The protective materials for solar cells of Comparative Examples 2-1 to 9 in which any one of the heat shrinkage rates of the films was outside the specified range of the present invention were inferior in moisture resistance and / or interlayer strength.
On the other hand, the protective materials for solar cells of Examples 2-1 to 5 are all excellent in appearance and excellent in moisture resistance and interlayer strength.

Example 3-1
An adhesive coating solution B-10 was applied to a 38 μm silicone release PET film so as to have a solid content of 20 g / m ² and dried to form an adhesive layer (i) surface having a thickness of 20 μm. Moisture-proof film B-10 is bonded to the surface of the pressure-sensitive adhesive layer (i), then the silicone release PET film is peeled off, and the intermediate film E-1 is bonded to the other pressure-sensitive adhesive surface, followed by curing at 40 ° C. for 4 days. A laminate was prepared. Further, a fluororesin film was overlapped with the intermediate film E-1 surface of the produced laminate, and adhered by hot pressing at 90 ° C. for 30 seconds to produce a solar cell protective material F-3-1 having a thickness of 582 μm. Various measurements and evaluations were performed using the obtained solar cell protective material F-3-1. The results are shown in Table 6.

Example 3-2
A protective material F-3-2 for a solar cell having a thickness of 222 μm was produced in the same manner as in Example 3-1, except that the intermediate film was changed to E-2. Using the obtained solar cell protective material F-3-2, various measurements and evaluations were performed. The results are shown in Table 6.

Example 3-3
A protective material F-3-3 for a solar cell having a thickness of 582 μm was produced in the same manner as in Example 3-1, except that the adhesive coating solution was changed to B-11. Various measurements and evaluations were performed using the obtained solar cell protective material F-3-3. The results are shown in Table 6.

Example 3-4
A protective material F-3-4 having a thickness of 222 μm was prepared in the same manner as in Example 3-2 except that the adhesive coating solution was changed to B-11. Various measurements and evaluations were performed using the obtained solar cell protective material F-3-4. The results are shown in Table 6.

Comparative Example 3-1
A solar cell protective material F-3-5 having a thickness of 582 μm was prepared in the same manner as in Example 3-1, except that the pressure-sensitive adhesive coating solution B-10 of Example 3-1 was changed to C-3. The obtained solar cell protective material F-3-5 was used for various measurements and evaluations. The results are shown in Table 6.

Comparative Example 3-2
A solar cell protective material F-3-6 having a thickness of 272 μm was produced in the same manner as in Example 3-1, except that the intermediate film E-1 of Example 3-1 was changed to E-3. The obtained solar cell protective material F-3-6 was used for various measurements and evaluations. The results are shown in Table 6.

Comparative Example 3-3
A solar cell protective material F-3-7 having a thickness of 582 μm was produced in the same manner as in Example 3-1, except that the moisture-proof film C-1 of Example 3-1 was changed to C-4. The obtained solar cell protective material F-3-7 was used for various measurements and evaluations. The results are shown in Table 6.

Comparative Example 3-4
Same as Example 3-1, except that the adhesive coating solution B-10 of Example 3-1 was changed to the adhesive coating solution B-13 and the thickness after drying was 6 μm. Thus, a solar cell protective material F-3-8 having a thickness of 568 μm was produced. Various measurements and evaluations were performed using the obtained solar cell protective material F-3-8. The results are shown in Table 6.

As can be seen from Table 6, in Examples 3-1 to 4 having the configuration of the present invention, the moisture-proof property was not deteriorated for a long time, and the occurrence of delamination was prevented. Further, Comparative Example 3-2 using an intermediate film having a melting point exceeding the range of the present invention is inferior in moisture resistance with time and insufficient in preventing the occurrence of delamination, and has a tensile storage elastic modulus of the present invention. Comparative Example 3-1 using a pressure-sensitive adhesive layer deviating from the above range is inferior in moisture resistance over time, and Comparative Example 3-4 using an adhesive layer instead of the pressure-sensitive adhesive layer is moisture-proof over time. And inferior in preventing delamination. In Comparative Example 3-3 using a moisture-proof film having a moisture-proof film having a water vapor transmission rate higher than 0.1 [g / (m ² · day)], the degree of deterioration of the water vapor transmission rate is not inferior, but PC48 The later water vapor permeability was high, which was not preferable for practical use.

Example 4-1
The adhesive coating liquid B-14 is applied and dried on the fluorine resin film A-1 so that the solid content is 20 g / m ^2, and the formed adhesive layer surface having a thickness of 20 μm is bonded to the metal oxide layer surface of the moisture-proof film. Then, it was cured at 40 ° C. for 5 days to produce a solar cell protective material having a thickness of 82 μm, and various evaluations were performed. The results are shown in Table 7 below. The initial water vapor transmission rate of the solar cell protective material was 0.01 [g / (m ² · day)].

Examples 4-2 and 4-3
A solar cell protective material having a thickness of 82 μm was produced in the same manner as in Example 4-1, except that the pressure-sensitive adhesive coating solution or adhesive coating solution shown in Tables 3 and 7 was used. Various evaluations were performed in the same manner as in Example 4-1, using the produced solar cell protective material. The results are shown in Table 7 below. The initial water vapor transmission rate of each solar cell protective material was 0.01 [g / (m ² · day)].

Examples 4-4 and 4-5 and Comparative Example 4-1
A laminated moisture-proof film composed of a weather-resistant film, an adhesive layer and a moisture-proof film was prepared in the same manner as in Example 4-1, except that the pressure-sensitive adhesive coating solution or adhesive coating solution shown in Tables 3 and 7 was used. Furthermore, the pressure-sensitive adhesive coating solution or adhesive coating solution shown in Table 3 is applied and dried on the moisture-proof film so as to have a solid content of 20 g / m ^2, and the formed 20 μm-thick adhesive layer and the moisture-proof film inorganic layer surface Was then cured at 40 ° C. for 5 days to produce a solar cell protective material having a thickness of 164 μm (weather-resistant film / adhesive layer / moisture-proof film / adhesive layer / moisture-proof film). Various evaluations were performed in the same manner as in Example 4-1, using the produced solar cell protective material. The results are shown in Table 7. The initial water vapor permeability of each solar cell protective material was 0.01 [g / (m ² · day)].

The solar cell protective material of the present invention solves the problem of poor appearance and is excellent in interlayer adhesion strength, peel strength, durability, weather resistance, moisture resistance and long-term moisture resistance.
Furthermore, the solar cell module using the solar cell protective material of the present invention can not only achieve a good appearance but also prevent a decrease in power generation efficiency.

Claims

A protective material for a solar cell in which a fluororesin film, a pressure-sensitive adhesive layer (i) comprising a pressure-sensitive adhesive (i), and a resin film having a metal oxide layer are laminated in this order, and the metal oxide layer The thickness of the substrate of the resin film having a thickness of 30 μm or less, the thickness of the pressure-sensitive adhesive layer (i) is 13 to 45 μm, and the pressure-sensitive adhesive layer (i) is 100 ° C., frequency 10 Hz, strain 0.1%. A solar cell protective material having a tensile storage elastic modulus of 5.0 × 10 4 to 5.0 × 10 5 Pa.
The solar cell protective material according to claim 1, wherein the pressure-sensitive adhesive (i) is a pressure-sensitive adhesive containing no carboxyl group or amino group.
The solar cell protective material according to claim 1 or 2, wherein a base material of the resin film having the metal oxide layer is a polyester film.
The water vapor permeability at a temperature of 40 ° C and a relative humidity of 90% of the resin film having the metal oxide layer is less than 0.1 [g / (m 2 · day)]. Protective material for solar cells.
A fluorine-based resin film, a pressure-sensitive adhesive layer (i) composed of a pressure-sensitive adhesive (i), a resin film having a metal oxide layer, a pressure-sensitive adhesive layer (ii) composed of a pressure-sensitive adhesive or an adhesive, and a melting point of 180 ° C. or higher. The protective material for a solar cell according to any one of claims 1 to 4, wherein a high melting point film having a heat shrinkage rate of 0.5% or less is laminated in this order.
6. The fluororesin film, an intermediate film having a melting point of 150 ° C. or less, an adhesive layer (i) comprising an adhesive (i), and a resin film having a metal oxide layer are laminated in this order. The protective material for solar cells in any one.
The solar cell protective material according to claim 6, wherein the intermediate film has a thickness of 50 to 600 µm.
The solar cell protective material according to claim 6 or 7, wherein the intermediate film contains a polyethylene resin as a main component.
The solar cell protective material according to any one of claims 6 to 8, which has the pressure-sensitive adhesive layer and the intermediate film on the metal oxide layer side of the moisture-proof film.
The solar cell protective material according to any one of claims 1 to 9, wherein a thickness of a base material of the resin film having the metal oxide layer is thinner than a thickness of the fluororesin film.
The tensile storage elastic modulus of the pressure-sensitive adhesive layer (i) comprising the pressure-sensitive adhesive (i) at 0 ° C., a frequency of 10 Hz, and a strain of 0.1% is 1.0 × 10 6 to 1.0 × 10 8 Pa. Item 11. The solar cell protective material according to any one of Items 1 to 10.
The solar cell protective material according to any one of claims 1 to 11, wherein the pressure-sensitive adhesive layer (i) comprising the pressure-sensitive adhesive (i) has a glass transition point of 0 ° C or lower.
The protective material for solar cells according to any one of claims 1 to 12, wherein the initial water vapor permeability is less than 0.1 [g / (m 2 · day)].
The solar cell protective material according to any one of claims 1 to 13, which is used in a vacuum lamination process having a maximum temperature of less than 150 ° C.
A solar cell module comprising the solar cell protective material according to any one of claims 1 to 14.
A solar cell protective material having a weather resistance layer, an adhesive layer 1 and a moisture-proof layer 1 having an inorganic layer on a base material in this order, wherein the glass transition point of the adhesive layer 1 is 0 ° C. or lower. Protective layer.
The protective material for solar cells according to claim 16, wherein the interlayer strength between the weather resistant layer and the moisture-proof layer 1 is 10 N / 15 mm or more after the condensation freezing test, and the degradation rate of the interlayer strength is less than 20%.
The solar cell protective material according to claim 16 or 17, wherein the adhesive layer 1 contains an acrylic pressure-sensitive adhesive.
The solar cell protective material according to any one of claims 16 to 18, wherein the base material of the moisture-proof layer 1 is a polyester film.
The solar cell protective material according to any one of claims 16 to 19, further comprising an adhesive layer 2 and a moisture-proof layer 2 having an inorganic layer on the substrate.
The solar cell protective material according to claim 20, wherein the adhesive layer 2 has a tensile storage elastic modulus of 5.0 × 10 4 to 5.0 × 10 5 Pa at 100 ° C., a frequency of 10 Hz, and a strain of 0.1%.
The solar cell protection according to claim 20 or 21, wherein the adhesive layer 2 has a tensile storage elastic modulus of 1.0 × 10 6 to 1.0 × 10 8 Pa at 0 ° C., a frequency of 10 Hz, and a strain of 0.1%. Wood.
The solar cell protective material according to any one of claims 16 to 22, wherein the weather-resistant layer is a 2-ethylene-4-fluoroethylene copolymer film.
The moisture barrier layer 1 and / or the moisture barrier layer 2 has a water vapor transmission rate of less than 0.1 [g / (m 2 · day)] at a temperature of 40 ° C. and a relative humidity of 90%, and the water vapor transmission rate after the condensation freezing test. The solar cell protective material according to any one of claims 16 to 23, which has a degree of degradation of less than 3.
The solar cell protective material according to any one of claims 16 to 24, wherein the thickness of the base material is thinner than the thickness of the fluororesin film.
The solar cell protective material according to any one of claims 16 to 25, which is used in a vacuum lamination step having a maximum temperature of less than 150 ° C.
A solar cell module comprising the solar cell protective material according to any one of claims 16 to 26.