TWI529064B - Protective backsheet for solar cell and solar cell module - Google Patents

Description

Solar cell back protection sheet and solar cell module

The present invention relates to a solar cell back surface protective sheet comprising a weather resistant flame retardant resin layer, an easy adhesive layer and a plastic film. Furthermore, the present invention relates to a solar cell module using the solar cell back protective sheet.

In recent years, due to the increased awareness of environmental issues, solar cells, which are clean energy sources without environmental pollution, have attracted attention and are being researched and put into practical use based on the use of solar energy as a useful energy resource. There are various forms of solar cell elements, and as a representative thereof, a crystalline germanium solar cell element, a polycrystalline germanium solar cell element, an amorphous germanium solar cell element, a copper indium selenide solar cell element, and a compound are known. Semiconductor solar cell components, etc.

In the solar cell module, the simple form is a configuration in which a filler and a glass plate are sequentially stacked on both surfaces of the solar cell element. The glass plate is excellent in transparency, weather resistance, and abrasion resistance, and is now generally used as a sealing sheet on the light receiving side of the sun. However, in the non-light-receiving side where transparency is not necessary, the company is continuing to develop solar cell back protective sheets other than glass sheets due to cost, safety, and processability considerations (hereinafter, also referred to as "back protection sheets"). ) to replace the glass plate.

The back protective sheet may, for example, be a single-layer film such as a polyester film; or a sheet of a vapor-deposited layer of a metal oxide or a non-metal oxide provided on a polyester film or the like, or a laminated polyester film or a fluorine-based film, A multilayer film of a film such as an olefin film or an aluminum foil (Patent Documents 1 to 3).

In order to improve dimensional stability, Patent Document 4 has proposed thickness A back protective sheet having a fluorine-containing resin sheet having a specific structure of 30 μm or less. In another example in which a fluorine-based resin sheet is used, Patent Document 5 discloses a sheet obtained by forming a bonding resin layer containing an aziridine group on a film formed of a fluorine-containing resin or a non-fluorine-containing resin having a specific structure. . Further, in order to achieve weather resistance, heat resistance, color retention, adhesion between the layer and the sealing material, and scratch resistance, Patent Document 6 proposes to use a back surface protective sheet of an amorphous fluoropolymer.

Patent Document 7 proposes a back protective sheet which is a plastic film substrate, an adhesive layer, a water vapor barrier layer, a resin containing a vinyl copolymer (A), a polyisocyanate compound (B), and a polyester (C). A back protective sheet in which a light-resistant resin formed of a composition is laminated. Further, Patent Document 8 proposes a laminated sheet which is a laminated sheet in which an outer layer sheet (back surface protective sheet or front sheet) and a sealing resin are laminated and integrated. It has been described that the use of the polyphenylene ether-based resin layer as an outer layer sheet is excellent in durability, flame retardancy, and dimensional stability, and the adhesion to the sealing resin layer is favorably maintained, and the workability can be improved.

Further, it has been proposed to provide a coating layer containing a phosphorus-based or inorganic-based flame retardant in a thermoplastic resin film which is not flame-retardant, and has a UL equivalent to the US UNDERWRITERS LABORATORIES company specification (hereinafter, abbreviated as UL). A laminated film of a flame retardant degree of HB and V-2 specified in 94 is proposed for use in a so-called solar cell (Patent Documents 9 to 12).

Further, in Patent Document 13 of the patent document which is published after the application of the priority application, the applicant of the present invention proposes to provide a solar cell back surface which is excellent in cost, abrasion resistance, long-term outdoor weather resistance, and long-term heat and humidity resistance. The opposite resin composition of the protective sheet. Specifically, it is included The acrylic copolymer (A), the polyisocyanate compound (B), the white pigment (C) having an average particle diameter of 200 to 400 nm, and the particles having an average particle diameter of 5 to 100 nm having a melting point of 120 ° C or higher or no melting point (D). Specific acrylic copolymer (glass transition temperature of 0 to 50 ° C, weight average molecular weight of 30,000 to 150,000, hydroxyl value of 2 to 100 (mgKOH / g), aromatic ring content of up to 50% by weight), and specific isocyanate Further, it has been found that by using particles (D) having an average particle diameter of 5 to 100 nm, the abrasion resistance of the coating film can be improved without impairing the elongation and flexibility of the light-resistant resin layer (1). The above invention is completed. In addition, in the coating material for imparting flame retardancy to the solar cell back surface protective sheet, a coating agent containing an inorganic pigment and a flame retardant in a fluorine-based resin has been proposed, and HB which satisfies UL-94 has been described. specification. Further, Patent Document 15 describes a solar battery module including a flame retardant in at least one of a surface protective material layer, a sealing material layer, an inner protective material layer, and a base material layer.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] JP-A-2004-200322

[Patent Document 2] JP-A-2004-223925

[Patent Document 3] JP-A-2001-119051

[Patent Document 4] JP-A-2003-347570

[Patent Document 5] JP-A-2004-352966

[Patent Document 6] Japanese Patent Publication No. 2010-519742

[Patent Document 7] JP-A-2008-098592

[Patent Document 8] JP-A-2011-146671

[Patent Document 9] JP-A-2009-179037

[Patent Document 10] JP-A-2010-89334

[Patent Document 11] JP-A-2010-120321

[Patent Document 12] JP-A-2010-149447

[Patent Document 13] JP-A-2011-228381

[Patent Document 14] JP-A-2011-162598

[Patent Document 15] JP-A-2012-015204

A variety of proposals have been made so far for the high performance of solar cell modules. In order to achieve a flame retardancy, a method of using a fluorine-based resin for a member such as a sealing material or a back surface protective sheet, or a film containing a flame retardant for a thermoplastic resin film has been proposed.

The flammability of a general polymer material is evaluated by the HB test or the V (VTM) test specified in UL-94 above, from the time of ignition to the time of fire suppression. In the above conventional examples, a laminated film which satisfies the HB-defined HA-94 and the flame retardancy of V-2 has been proposed. However, the specifications of the flammability of the solar cell module and the solar cell back protective sheet are defined as IEC61730-1, IEC61730-2, and UL-1703 which are the standard specifications of the solar cell, and the solar cell back protective sheet is passed through UL. The flame spread test (radiant panel test, ASTM E162) specified in -1703 is required by the market. The flame spread test is a flame spread obtained by (i) combustion temperature (heat release factor), (ii) combustion speed (≒ flame diffusion coefficient), which is the basis for evaluating the flame spread coefficient, and after the fire is extinguished The HB test or V (VTM) test evaluated at the time is not the same.

In order to improve flame retardancy, a method of using a glass plate for a back protective member Although effective, as described above, replacement of materials other than glass sheets is being carried out based on cost, safety, and processability. Therefore, it is an important subject to provide a back surface protection sheet that satisfies UL-1703 in the solar cell back surface protection sheet. In addition to the flame retardancy, the solar cell module is also required to withstand long-term heat and humidity resistance under outdoor harsh conditions and excellent long-term outdoor weather resistance. Furthermore, in order to accelerate the spread of solar cell modules, it is important to provide them inexpensively.

In view of the above background, the present invention provides a flame retardancy having characteristics satisfying the flame spread test prescribed in UL-1703, and is excellent in long-term heat and humidity resistance and long-term outdoor weather resistance, and is inexpensively provided. A solar cell back protective sheet and a solar cell module using the solar cell back protective sheet.

In order to achieve the above object, the present inventors have continued to study the results of the present invention, and have found that the following aspects can solve the problems of the present invention and complete the present invention. In other words, the solar cell back surface protective sheet of the present invention comprises a weather-resistant flame-retardant resin layer (1) having a film thickness t (μm), a plastic film (2), and an easy-adhesive layer (3). The surface on one side of the solar cell back surface protective sheet is composed of the weather resistant flame-retardant resin layer (1). Further, the other surface of the solar cell back surface protective sheet is composed of the above-mentioned easy-adhesive layer (3). Further, the weather-resistant flame-retardant resin layer (1) contains a phosphorus-based flame retardant (A) selected from the group consisting of a phosphazene compound, a phosphinic acid compound, and (poly)phosphoric acid melamine, and an acrylic resin. (B). The acrylic resin (B) has a glass transition temperature of 0 to 70 ° C, a weight average molecular weight of 15,000 to 150,000, a hydroxyl value of 2 to 30 (mgKOH/g), and a film thickness of the weather resistant flame retardant resin layer (1). t is too The total film thickness of the solar cell back surface protective sheet is 2.5 to 20%, and the total phosphorus concentration of the phosphorus-based flame retardant (A) in the weather resistant flame retardant resin layer (1) is 2.1 to 14.2% by weight.

The hydroxy group of the acrylic resin (B) is preferably 5 to 20 (mgKOH/g).

The weather-resistant flame-retardant resin layer (1) preferably contains 20 to 50% by weight of a phosphorus-based flame retardant (A).

The total phosphorus concentration from the phosphorus-based flame retardant (A) is preferably from 3 to 10% by weight.

The solar cell module of the present invention includes a solar cell surface sealing sheet (I) located on the light receiving surface side of the solar cell, a sealing material layer (II) located on the light receiving surface side of the solar cell, and a solar cell element (III). a solar cell module in which the sealant layer (IV) on the non-light-receiving surface side of the solar cell and the solar cell back surface protective sheet (V) adjacent to the non-light-receiving surface side sealant layer (IV) are The weather-resistant flame-retardant resin layer (1) constituting the solar cell back surface protective sheet is located farthest from the solar cell surface sealing sheet (I).

According to the present invention, it is possible to provide a solar cell back surface protection sheet which has a flame retardancy which satisfies the characteristics of the flame spread test specified in UL-1703, and which is excellent in long-term heat and humidity resistance and long-term outdoor weather resistance, and which can be inexpensively provided. A solar cell module using the solar cell back protective sheet.

Hereinafter, the present invention will be described in detail. Moreover, as long as the object of the present invention is met, it is needless to say that other embodiments may also fall within the scope of the present invention. . In addition, in the present specification, the description of the arbitrary number A to the arbitrary number B is larger than the range A and the number B is smaller.

The solar cell back protective sheet is as described above and is required to meet the flame spread test specified in UL-1703. In addition, the life of solar cell modules is now required to be guaranteed for 15 to 25 years. The long-term weather resistance and long-term heat and humidity resistance of solar cell back protection sheets are also necessary. Furthermore, the solar cell back protective sheet is also required to satisfy the withstand voltage.

From the viewpoint of ensuring the withstand voltage, the film thickness of the solar cell back surface protective sheet may vary depending on the thickness of the material or the sealing material to be formed, but it is preferably 250 μm or more. Moreover, from the viewpoint of flexibility, productivity, and cost of the solar cell back surface protective sheet, it is preferably a thickness of 400 μm or less. Moreover, it is also important to provide a solar cell back protective sheet inexpensively. Among them, it is preferable to increase the ratio of the thickness of the plastic film (2) mainly constituting the member of the solar cell back surface protective sheet while preventing the combustion of the entire solar cell back surface protective sheet from expanding, and achieving fire resistance or fire extinguishing property. From this point of view, when the thickness of the solar cell back surface protective sheet is in the range of 250 to 400 μm, the thickness of the plastic film (2) is preferably in the range of 125 to 250 μm. Further, the material of the plastic film (2) is not particularly limited, but a thermoplastic resin such as a polyester film or an olefin film is preferable from the viewpoint of inexpensive supply.

As a result of continuous intensive research by the present inventors, it has been surprisingly found that the flame retardancy which satisfies the characteristics of the flame spread test specified in UL-1703 can be found by satisfying the following configurations (i) to (vi). The solar cell back protective sheet is excellent in long-term heat and humidity resistance and long-term outdoor weather resistance, and can be supplied inexpensively.

(i) The solar cell back surface protective sheet of the present invention comprises a weather-resistant flame-retardant resin layer (1) having a film thickness t (μm), a plastic film (2), and an easy-adhesive layer (3).

(ii) In the solar cell back surface protective sheet, the outermost layer disposed on the solar cell element side is an easy-adhesive layer (3), and the other outermost layer is a weather-resistant flame-retardant resin layer (1).

(iii) The weather-resistant flame-retardant resin layer (1) contains a phosphorus-based flame retardant (A) selected from the group consisting of a phosphazene compound, a phosphinic acid compound, and a (poly)phosphoric acid melamine, and an acrylic resin. (B).

(iv) The acrylic resin is a glass transition temperature of 0 to 70 ° C, a weight average molecular weight of 15,000 to 150,000, and a hydroxyl value of 2 to 30 (mgKOH/g).

(v) The film thickness t of the weather resistant flame-retardant resin layer (1) is 2.5 to 20% of the total film thickness of the solar cell back surface protective sheet.

(vi) The total phosphorus concentration from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is 2.1 to 14.2% by weight.

The above (i) to (vi) are described in detail below.

The solar cell back surface protective sheet of the present invention is provided at a low cost by satisfying (i) to (iii) while achieving weather resistance and flame retardancy, and can maintain good adhesion in the solar cell module. In the method of imparting flame retardancy, a method of adding a flame retardant to the entire solar cell back protective sheet or a method of separately providing a flame retardant layer and a weather resistant layer, and adding a flame retardant to the intermediate layer may be considered. In the present invention, a weather resistant resin is disposed from the outermost layer farthest from the solar cell element, and a flame retardant is added thereto. The weather-resistant flame-retardant resin layer (1) is attached to the inside of the solar cell back protective sheet to further protect the solar cell module from purple External factors such as outside lines or physical impulses. Therefore, the adhesion to the inner layer can be improved while suppressing the deterioration of the output of the solar cell element. This result can further confirm the effect of flame retardancy.

Incidentally, as the flame retardant to be generally used, a phosphorus-based flame retardant, a nitrogen-based flame retardant, a bismuth-based flame retardant, an inorganic flame retardant, and the like can be exemplified.

In the case of a phosphorus-based flame retardant, melamine phosphate, melamine polyphosphate, strontium phosphate, strontium polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amide ammonium phosphate, ammonium polyphosphate amide, and amino phosphonic acid can be exemplified. a phosphate compound or a polyphosphate compound such as an ester or a polyphosphate urethane, a red phosphorus, an organic phosphate compound, a phosphazene compound, a phosphonic acid compound, a phosphinic acid compound, a phosphine oxide compound, or a phosphine ( Phosphorane) a compound, a phosphoamide compound, and the like.

As the nitrogen-based flame retardant, a triazine-based compound such as melamine, melam, meleme, melome, melamine cyanurate or the like can be exemplified. , cyanuric acid compound, iso-cyanuric acid compound, triazole compound, tetrazole compound, diazo compound, urea, etc.; As the oxime-based flame retardant, a polyoxygen compound or a decane compound or the like can be exemplified.

The halogen-based flame retardant may, for example, be a halogenated compound such as a halogenated bisphenol A, a halogenated epoxy compound or a halogenated phenoxy compound, a halogenated oligomer or a polymer.

Examples of the inorganic flame retardant include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, and calcium hydroxide, tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, and oxidation. Zinc, molybdenum oxide, cerium oxide, nickel oxide, zinc carbonate, magnesium carbonate, calcium carbonate, barium carbonate, Zinc borate, hydrated glass, and the like.

There are many types of flame retardants as shown in the above examples. Among the many flame retardants, the inventors have continuously studied the results to find (iii) a phosphorus-based flame retardant (A) of any one of a phosphazene compound, a phosphinic acid compound, and a (poly)phosphoric acid melamine. Useful.

First, the reason why the flame retardant other than the above (iii) is not suitable will be explained. In order to exhibit a flame retardancy effect, a nitrogen-based flame retardant or an inorganic flame retardant is required to increase the amount of the flame retardant to be added. Along with this, there is a problem that the weather resistance or the moist heat resistance of the weather-resistant flame-retardant resin layer (1) is greatly reduced. Further, since the halogen-based flame retardant is subjected to the damp heat resistance test or the weather resistance test, the weather-resistant flame-retardant resin layer is largely yellowed, so that it is avoided in appearance consideration. Moreover, in the weather resistance test, there is a problem that the flame retardant promotes deterioration of the acrylic resin (B). When considering the environmental concerns in recent years, the use of halogen-based flame retardants is not good.

Further, the phosphorus-based flame retardant is preferable in that it exhibits flame retardancy with a relatively small addition amount, but is, for example, (poly)ammonium phosphate or (poly)phosphoric acid amine used for a flexible printed circuit board or the like. Since the carbamate is slowly decomposed by the passage of the heat and humidity resistance test to produce a phosphoric acid which is a strong acid, it is not preferable. The produced phosphoric acid becomes a hydrolysis catalyst of the acrylic resin (B), and the weather-resistant flame-retardant resin layer (1) is largely deteriorated. Therefore, even if it is a phosphorus-based flame retardant, it is not preferable that the flame retardant which hydrolyzes in the heat-resistant test to generate an acid is not preferable.

The phosphorus-based flame retardant (A) of the present invention can effectively exhibit flame retardancy in a small amount of addition to the extent that weather resistance or moist heat resistance is not affected. Further, it is excellent in a point where no acid is generated by hydrolysis. Moreover, the phosphorus-based flame retardant (A) itself has high heat and humidity resistance, and hardly undergoes heat and humidity. hydrolysis. Therefore, it is possible to effectively prevent the occurrence of a decrease in the adhesion of the weather-resistant flame-retardant resin layer (1) to the plastic film (2). In other words, by using the phosphorus-based flame retardant (A) of the present invention, the heat-and-moisture resistance is improved more than that of the acrylic resin (B) alone, and the adhesion with time is favorably maintained, in addition to the flame retardant. In addition to the effect, it is considered that the effect is lowered (i) the combustion temperature (heat release factor), and (ii) the combustion rate (≒ flame diffusion coefficient) is lowered.

Among the phosphorus-based flame retardants (A), in particular, the phosphazene compound and the phosphinic acid compound are highly hydrophobic and highly filler-like compounds, so that by using these compounds, the weather resistance and flame retardancy can be more effectively improved. The hydrophobicity of the resin layer (1). That is, it is possible to further exhibit high moist heat resistance even when the acrylic resin (B) monomer is used. Therefore, it is very suitable as a flame retardant for solar cell back protection sheets.

As the phosphazene compound, a phosphazene oligomer exemplified in the following general formula (1) or (2) can be exemplified.

Wherein, in the general formula (1) or (2), each of R ¹ and R ² is a hydrogen atom or a halogen-free monovalent organic group ^; and the monovalent organic group of R ¹ and R ² represents a phenyl group, an alkyl group, The amine group, the allyl group, the aforementioned phenyl group and the like may each further have a halogen-free substituent. As the substituent, it may be suitably selected from the group consisting of a hydroxyl group, an amine group, a cyano group, and a nitro group. n is an integer from 3 to 10.

The above R ¹ or R ² is preferably a phenyl or alkyl cyclophosphazene, and the cyclophosphazene is preferably a tricyclic phosphazene. Specifically, a hexaalkyloxytricyclophosphazene or a hexaphenoxytricyclophosphazene, and a hexaphenoxytricyclophosphazene is preferred.

As the hexaalkyloxytricyclophosphazene, hexamethoxytricyclophosphazene, hexaethoxytricyclophosphazene, hexapropoxytricyclophosphazene or the like can be exemplified.

In the case of hexaphenoxytricyclophosphazene, in addition to the unsubstituted hexaphenoxytricyclophosphazene, a hexaphenoxytricyclophosphazene having a substituent such as a hydroxyl group or a cyano group can be exemplified.

As the phosphinic acid compound, the phosphinates exemplified in the following general formula (3) can be exemplified.

Wherein, in the general formula (3), R1 and R2 are the same or different, and are represented by a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group, and M represents at least one selected from the group consisting of Mg, A metal of a group consisting of Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, and K, and n is an integer of 1 to 4. As a preferable compound, a phosphinate in which M is Mg, Ca or Al, and an aluminum phosphinate in which M is Al is particularly preferable. Specifically, it is preferred that R1 and R2 are an alkyl group and n=3 of a dialkylphosphinic acid aluminum salt.

In the case of (poly)phosphoric acid amide, a compound in which the phosphoric acid and melamine exemplified in the following general formula (4) are in a salt state can be exemplified. In the following general formula (4), n is preferably 1 to 10, and n is 2 or more. Melamine."

The above-mentioned phosphorus-based flame retardant (A) may be used singly or in combination of a plurality of compounds in each compound group, or may be arbitrarily combined from a plurality of compound groups.

The acrylic resin (B) is one that satisfies the conditions of the above (iv). The acrylic resin (B) is responsible for preventing the influence of deterioration due to ultraviolet rays or physical smashing, and also functions as a binder, so that the phosphorus-based flame retardant (A) is not in the weather-resistant flame-retardant resin layer (1). Will agglutinate and exist uniformly.

By using the acrylic resin (B), it is suitable as a binder for the weather resistant flame-retardant resin layer (1) excellent in weather resistance or chemical resistance. In order to further improve the weather resistance, the acrylic resin (B) may be combined with an ultraviolet absorber, a light stabilizer, an antioxidant, or the like.

In the acrylic resin (B), an acrylic resin produced by a polymerization reaction of one or two or more kinds of general acrylic monomers in combination with the desired properties may be mentioned. For example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (methyl) An aliphatic (meth) acrylate such as stearyl acrylate; or an alicyclic (meth) acrylate such as cyclohexyl methacrylate or cyclopentadienyl methacrylate; or benzyl (meth) acrylate A (meth) acrylate or the like containing a hydroxyl group such as a (meth)acrylic acid hydroxy acrylate.

The glass transition temperature of the acrylic resin (B) is preferably from 0 to 70 ° C, and preferably from 20 to 50 ° C. When the glass transition temperature of the acrylic resin (B) exceeds 70 ° C, the adhesion of the obtained weather-resistant flame-retardant resin layer to the substrate during wet heat can not be ensured, and floating or peeling occurs. In the case where the weather-resistant flame-retardant resin layer is floated or peeled off, the solar cell back protective sheet may not be able to maintain flame retardancy.

The solar cell back protective sheet of the present invention is usually produced by applying a weather-resistant flame-retardant resin composition (1') to a plastic film (2), drying it, and rolling it into a roll shape, and then rolling the roll at 40 to 60 ° C. The weather-resistant flame-retardant resin layer (1) is sufficiently cured (hereinafter referred to as aging) by leaving it in the environment for about 1 to 2 weeks. When the glass transition temperature of the acrylic resin (B) is lower than 0 ° C, the heat resistance of the weather resistant flame-retardant resin layer (1) is poor, and even if the phosphorus-based flame retardant (A) is provided, the solar cell back protective sheet cannot be maintained. Flame retardant.

Here, the glass transition temperature refers to a glass transition temperature measured by differential scanning calorimetry (DSC) in a resin obtained by drying a solution of the acrylic resin (B) to a solid content of 100%.

The polystyrene-equivalent weight average molecular weight of the acrylic resin (B) by gel permeation chromatography (GPC) is important from 15,000 to 150,000, preferably from 30,000 to 120,000, more preferably from 50,000 to 100,000.

When the weight average molecular weight of the copolymer (a) exceeds 150,000, the wettability of the weather-resistant resin layer to the plastic film is lowered, the adhesion is lowered, and the adhesion to the substrate during the moist heat is not ensured. Float or peel off. In the case where the weather-resistant flame-retardant resin layer is floated or peeled off, the solar cell back protective sheet may not be able to maintain flame retardancy. also When the molecular weight is too large, the viscosity of the weather resistant resin composition (1') becomes large, and the coating property is easily hindered. It is possible to adjust the viscosity at the time of coating by diluting with an organic solvent, but the thickness of the weather-resistant resin layer obtained by dilution becomes thin.

When the weight average molecular weight of the copolymer (a) is less than 15,000, the weather resistant resin layer obtained is weak and is easily scratched, and the thickness of the weather resistant resin layer passing through the weather resistance test is reduced. In addition, since the weather-resistant flame-retardant resin layer (1) is inferior in moisture-heat resistance, even if the phosphorus-based flame retardant (A) is present after the moist heat, the flame retardancy of the solar cell back surface protective sheet cannot be maintained.

Further, in order to impart high toughness, weather resistance, and moist heat resistance to the acrylic resin (B), a hydroxyl group is introduced into the acrylic resin (B), and a general crosslinking agent is crosslinked to obtain a higher crosslinking density. It is important. The hydroxyl value of the acrylic resin (B) is preferably from 2 to 30 mgKOH/g, more preferably from 5 to 20 mgKOH/g, in terms of solid content.

When the hydroxyl value of the acrylic resin (B) exceeds 30 mgKOH/g, the degree of crosslinking of the acrylic resin (B) becomes too large, so that the adhesion after the moist heat test is remarkably lowered, and floating or peeling can be seen. Therefore, in the case where the weather resistant flame-retardant resin layer (1) of the solar cell back surface protective sheet of the present invention uses the above-mentioned acrylic resin (B), after the damp heat test, the weather-resistant flame-retardant resin layer (1) will be self-made from the plastic film ( 2) Floating and peeling, it is inevitable that the flame retardancy cannot be maintained, and the problem of the present invention cannot be solved.

On the other hand, when the hydroxyl value of the acrylic resin (B) is less than 2 mgKOH/g, the reactivity with the crosslinking agent is remarkably lowered, so that the weather resistant resin layer (1) formed is brittle and extremely scratched. Due to the fragility, various tolerances are significantly poor. Also, due to weather resistant flame retardant resin layer (1) The heat and humidity resistance is poor, and even if the phosphorus-based flame retardant (A) is present after the moist heat, the flame retardancy of the solar cell back surface protective sheet cannot be maintained.

When the crosslinking agent is reactive with the hydroxyl group of the acrylic resin (B), a general crosslinking agent can be used, and examples thereof include a polyisocyanate compound, a polycyanate compound, a polyglycidyl compound, and a polyaziridine compound. .

From the viewpoint of durability or coating stability, an isocyanate compound is preferable as a crosslinking agent having a hydroxyl group-containing acrylic resin (B) and a functional group reactive with an isocyanate hydroxyl group. From the viewpoint of further improving durability, a polyisocyanate compound is preferred.

The polyisocyanate compound is formed to crosslink the acrylic resin (B) to form a strong and durable, stretchable property, flexibility, moldability, abrasion resistance, long-term weather resistance, long-term heat and humidity resistance, and chemical resistance. A resin layer is used. In order to prevent the obtained weather resistant resin layer from turning yellow to brown over time, it is preferred to use only an alicyclic or aliphatic compound.

As the alicyclic polyisocyanate compound, for example, isophorone diisocyanate, hydrogenated tolyl diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate or the like can be exemplified.

As the aliphatic polyisocyanate compound, for example, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, leucine diisocyanate or the like can be exemplified.

As the aromatic polyisocyanate compound, for example, diphenylmethane diisocyanate, toluene diisocyanate, naphthalene-1,5-diisocyanate, o-xylene diisocyanate, m-xylene diisocyanate, p-di can be exemplified. Toluene diisocyanate, triphenylmethane triisocyanate, polymethylene Polyphenyl isocyanate or the like.

The polyisocyanate compound may be a terminal isocyanate addition product, a biuret modified substance or a trimer isocyanate modified product which is a reaction product of the above compound with a glycol or a diamine.

In particular, when the polyisocyanate compound contains a trimerized isocyanate modified product, particularly a triisocyanate containing a trimerized isocyanate ring, it is preferred to obtain a more durable and stretchable weatherable resin layer. As the triisocyanate containing a trimeric isocyanate ring, specifically, a trimeric isocyanate-modified isophorone diisocyanate (for example, Desmodur Z4470 manufactured by Sumitomo Bayer Co., Ltd.), a trimerized isocyanate-modified hexa Methyl diisocyanate (for example, Sumidur N3300 manufactured by Sumitomo Bayer Carbamate Co., Ltd.), modified isocyanate modified toluene diisocyanate (for example, Sumidur FL-2, FL-3, FL manufactured by Sumitomo Bayeramide Co., Ltd.) -4, HL BA). Further, the trimer isocyanate ring may be further reacted with the polyester (c) having two or more reactive functional groups to increase the isocyanate group in one molecule, and the resulting urethane bond may further be combined with one equivalent. The isocyanate group reacts with allophanate, which in turn increases the isocyanate group in one molecule. As the polyester (c) having two or more functional groups reactive with an isocyanate group, a known polyester resin can be used.

Further, an isocyanate group of the above polyisocyanate compound may be used, for example, methanol, ethanol, n-pentanol, chlorohydrin, isopropanol, phenol, p-nitrophenol, m-cresol, acetamidineacetone, acetamidineacetic acid. A block modified body in which a block agent such as ethyl ester or ε-caprolactam is reacted and blocked.

Further, as the polyisocyanate compound, a polyester (d) having two or more functional groups reactive with an isocyanate group can also be used. A two-terminal isocyanate prepolymer obtained by reacting a diisocyanate compound (e) having an isocyanate group at its end. In the case where the polyisocyanate compound contains the above-mentioned two-terminal isocyanate prepolymer, the stretchability can be obtained in a small amount, and the strongness of the coating film is not impaired. The polyisocyanate compound may be used alone or in combination of two or more.

As the polyester (d) having two or more functional groups reactive with an isocyanate group, a well-known polyester resin can be used. For the diisocyanate compound (e) having an isocyanate group at both terminals, for example, toluene diisocyanate, naphthalene-1,5-diisocyanate, o-toluene diisocyanate, diphenylmethane diisocyanate, trimethyl group can be exemplified. Hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, lysine II Isocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated toluene diisocyanate, and the like.

In the polyisocyanate compound, the number of isocyanate groups of the polyisocyanate compound is preferably 0.1 to 5 times the total number of functional groups capable of reacting with the isocyanate group with respect to the acrylic resin (B). Good is 1~3 times. When the amount is less than 0.1 times, the crosslinking density is too low, and the solvent resistance, abrasion resistance, and weather resistance are not sufficient. When the ratio is more than 5 times, the isocyanate remains, and reacts with moisture in the air to become a seasonal property. The cause of change.

As the crosslinking agent, in addition to the above polyisocyanate compound, a well-known oxazoline compound may be contained, for example, 2,5-dimethyl-2-oxazoline, 2,2-(1,4-stretch Butyl)-bis(2-oxazoline) or anthraquinone compounds, such as diterpene isononanoate, diterpene sebacate, diammonium adipate.

The aromatic ring content in the acrylic resin (B) is at most 50% by weight It is preferable that it is 10% by weight or less, and it is preferable that the aromatic ring is not contained as much as possible. When the content of the aromatic ring in the acrylic resin (B) is more than 50% by weight, ultraviolet rays are absorbed, and yellowing of the weather-resistant flame-retardant resin layer (1) and deterioration of the coating film are caused, and weather resistance is liable to lower.

Further, the weather-resistant flame-retardant resin layer (1) may be added with inorganic fine particles or organic fine particles in order to improve the lubricity or barrier properties of the surface.

Specific examples of the inorganic fine particles include, for example, vermiculite, glass fiber, glass powder, glass beads, clay, wollastonite, iron oxide, cerium oxide, lithopone, pumice powder, Inorganic particles such as aluminum sulfate, zirconium silicate, dolomite, and sand iron. Further, the inorganic fine particles may contain impurities to the extent that they do not impair the properties. Further, the shape of the particles may be any shape such as a powder, a granule, a granule, a true spherical shape, a flat shape, or a fibrous shape.

Specific examples of the organic fine particles include polyolefin wax, polymethyl methacrylate resin, polystyrene resin, nylon resin, melamine resin, guanamine resin, phenol resin, urea resin, and the like. Polymer particles such as an anthracene resin, a methyl acrylate resin, or an acrylate resin, or a cellulose powder, a nitrocellulose powder, wood powder, recycled paper powder, rice bran powder, starch, or the like. The organic fine particles can be obtained by a polymerization method such as an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a soap-free polymerization method, a seed polymerization method, or a microsuspension polymerization method. Further, the organic particles may contain impurities to the extent that they do not impair their properties. Further, the shape of the particles may be any shape such as a powder, a granule, a granule, a flat plate, or a fiber.

Further, in the weather resistant flame-retardant resin layer (1), in order to enhance the strength of the weather-resistant flame-retardant resin layer obtained, it is possible to prevent the effects of the present invention from being impaired. It may contain various thermoplastic resins other than the acrylic resin (B). As the thermoplastic resin, for example, polypropylene, polyethylene, ethylene-vinyl acetate copolymer, polyisobutylene, polybutadiene, polystyrene, polycarbonate, polymethylpentene, ionic polymer can be exemplified. , acrylonitrile-butadiene-styrene resin, acrylic resin, polyvinyl alcohol, polyamide resin, polyacetal, epoxy resin, and the like.

The amount of the thermoplastic resin to be added is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, based on 100 parts by weight of the total of the acrylic resin (B). When it exceeds 50 parts by weight, the compatibility with other components may be lowered.

For the purpose of coloring, a pigment may be added to the weather resistant flame-retardant resin layer (1). As the pigment, those conventionally known can be used, and inorganic pigments such as carbon black, titanium oxide, zinc oxide, lead oxide, zinc sulfide, and zinc antimony or various organic pigments can be used.

The phosphorus-based flame retardant (A), particles, and pigment are preferably mixed with a dispersion resin or a dispersing agent as needed to prepare a paste, and then mixed with an acrylic resin (B) or the like. The acrylic resin (B) is preferably used as the dispersion resin, and is not particularly limited, and a polar group having excellent pigment dispersibility, for example, a hydroxyl group, a carboxyl group, a thiol group, an amine group, a guanamine group, or the like can be used. An acrylic resin such as a ketone group, a polyurethane resin, a polyurea resin, a polyester resin or the like. The dispersant may, for example, be a pigment derivative, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, a titanium coupling agent, a decane coupling agent or the like. Further, the surface of the pigment can be modified by a metal chelating agent, a resin coating or the like.

The weather resistant flame-retardant resin layer (1) of the present invention satisfies the above (v) (vi). That is, the film thickness t of the weather resistant flame-retardant resin layer (1) is the back surface of the solar cell. The total film thickness of the protective sheet is 2.5 to 20%. For example, in the case of a solar cell back surface protective sheet having a film thickness of 300 μm, the film thickness t of the weather resistant flame-retardant resin layer (1) is in the range of 7.5 to 60 μm. Further, the total phosphorus concentration from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is 2.1 to 14.2% by weight. By setting the film thickness t of the weather resistant flame-retardant resin layer (1) to the above range, and by setting the total phosphorus concentration to a specific range, it is possible to provide a solar cell back surface protective sheet which is excellent in flame retardancy and economy.

By setting the film thickness t of the weather-resistant flame-retardant resin layer (1) to the above range, a solar cell back surface protective sheet excellent in flame retardancy and economy can be obtained.

In terms of the thickness, the film thickness t of the weather-resistant flame-retardant resin layer (1) is 2.5% or more of the total film thickness of the solar cell back surface protective sheet, and the plastic film which is the main constituent member of the solar cell back surface protective sheet can be suppressed ( 2) The burning can meet the flame penetration test of UL-1703. On the other hand, when the film thickness t of the weather-resistant flame-retardant resin layer (1) is 20% or more of the total thickness of the solar cell back surface protective sheet, it becomes difficult to form a uniform layer, and it is more disadvantageous in terms of cost.

In addition, by setting the total phosphorus concentration of the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) to 2.1% or more, not only the flame retardancy of the coating film itself can be satisfactorily maintained, but sufficient carbonization can be formed. The film is effective in suppressing the burning of the plastic film (2) or the like. As a result, the specification value of the flame spread test can be satisfied. Moreover, by setting the total phosphorus concentration to 14.2% or less, the weather resistance and the moist heat resistance can be favorably maintained. The preferred range of the total phosphorus concentration from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is from 3 to 10% by weight. By setting the total phosphorus concentration from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) to 3 to 10% by weight, the sun can be more effectively used. The flame retardancy of the battery back protective sheet is more effective.

The weight of the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is preferably 10% by weight or more, more preferably 15% by weight or more, and still more preferably 20% by weight or more. Further, the weight of the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is preferably 60% by weight or less, more preferably 50% by weight or less. When the amount of the phosphorus-based flame retardant (A) is contained in the range of 10% by weight or more and 60% by weight or less, the flame retardancy, weather resistance, and moist heat resistance can be satisfactorily satisfied. In particular, by making 20% by weight or more, it is possible to effectively improve flame retardancy. In addition, by making 50% by weight or less, the blending amount of the acrylic resin (B) can be appropriately maintained, and the weather resistance and the moist heat resistance can be more satisfactorily maintained.

The phosphorus-based flame retardant (A) obtained from the phosphazene compound, the phosphinic acid compound, and the (poly)phosphoric acid amide used in the present invention hardly hydrolyzes in the moisture heat resistance test. However, even if a very small amount of acid is produced as a result of a small amount of hydrolysis, the acid becomes a catalyst during a very long period of time, and promotes hydrolysis of the side chain of the acrylic resin (B), and promotes a weather resistant flame-retardant resin layer. (1) Concerns about deterioration.

Next, the plastic film (2) used in the present invention will be described. For the plastic film (2) used in the present invention, for example, a polyester system such as polyethylene terephthalate, polybutylene terephthalate or polybutylene terephthalate can be used. a resin film; an olefin film of polyethylene, polypropylene, polycyclopentadiene or the like; a fluorine-based film of a polyvinyl fluoride, a polyvinylidene fluoride film, a polytetrafluoroethylene film, an ethylene-tetrafluoroethylene copolymer film, or the like; Acrylic film, triacetyl cellulose film. From the viewpoint of film rigidity and cost, a polyester resin film is preferred, and a polyethylene terephthalate film is preferred. The plastic film (2) can be one layer or two or more layers. Multilayer structure.

These plastic films (2) may be colorless and may also contain colored components such as pigments or dyes. The method of containing a coloring component is, for example, a method of preliminarily kneading a coloring component at the time of film formation of a film, a method of printing a coloring component on a colorless transparent film substrate, and the like. Further, the colored film may be used in combination with a colorless transparent film.

Next, the easy-adhesion layer (3) used in the present invention will be explained. The easy-adhesive layer (3) in the present invention is used as a layer for improving the adhesion between the plastic film (2) and the non-light-receiving side sealing material (IV), and is provided on one side of the solar cell back protective sheet. The outermost resin layer. Further, when the solar cell module is formed, the non-light-receiving side sealing material (IV) and the solar cell back surface protective sheet (V) of the present invention are bonded to the easy-adhesive layer (3), whereby The solar cell back protection sheet is mounted in the solar cell module.

The easy-adhesive layer (3) used in the present invention can be formed from a general adhesive containing various resins. Preferred examples thereof include a polyester resin, a urethane resin, and an acrylic resin. The resin may be used singly or in combination of two or more. It is also possible to use such resins for compositing.

The preferred polyester resin as the easy adhesive layer (3) is also included in the polyester resin having a hydroxyl group in addition to the polyester resin in which the carboxylic acid component reacts with the hydroxyl component (esterification reaction, transesterification reaction). Further, a polyester polyurethane resin obtained by reacting with an isocyanate compound, or a polyester polyurethane polyurea resin obtained by further reacting with a diamine component.

The carboxylic acid component of the polyester resin constituting the easy adhesive layer (3) may, for example, be benzoic acid, p-tris-butyl benzoic acid, phthalic anhydride, or isoindole. Acid, p-citric acid, succinic anhydride, adipic acid, sebacic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, fumaric acid, itaconic acid, tetrachlorophthalic anhydride, 1, 4-cyclohexanedicarboxylic acid, 1,2,4-benzenetricarboxylic anhydride, methylcyclohexene tricarboxylic anhydride, pyromellitic anhydride, ε-caprolactone, fatty acid.

The hydroxyl component of the polyester resin constituting the easy adhesive layer (3), in addition to ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, and two Examples of diol components such as propylene glycol, neopentyl glycol, triethylene glycol, 3-methylpentanediol, and 1,4-cyclohexanedimethanol include glycerin, trimethylolethane, and trishydroxyl. A polyfunctional alcohol such as methyl propane, trihydroxymethylaminomethane, pentaerythritol or dipentaerythritol.

A designated polyester resin obtained by polymerizing these carboxylic acid components and a hydroxyl component by a usual method can be used as the easy-adhesive layer (3).

The urethane-based resin of the easy-adhesion layer (3) is obtained by reacting a hydroxyl component other than the polyester resin having a hydroxyl group with an isocyanate compound.

As the above hydroxyl component, polymerization of a polyether polyol, an acrylic polyol, a polybutadiene polyol, or the like which is added with polyethylene glycol, polypropylene glycol, ethylene oxide or propylene oxide, or the like can be used. Polyols and the like.

The above isocyanate compound can be exemplified by the same as the polyisocyanate compound (C) described later. Trimethylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), methylene bis(4,1-phenylene) diisocyanate (MDI), methyl 3-isocyanate-3, a diisocyanate such as 5,5-trimethylcyclohexyl isocyanate (IPDI) or benzoyl diisocyanate (XDI), or a trimethylolpropane adduct of such a diisocyanate, or a diisocyanate thereof Trimeric isocyanate of polymer, these two different A biuret combination of a cyanate ester, a polymerizable diisocyanate or the like.

With respect to the monomer constituting the acrylic resin of the easy adhesive layer (3), general formula (a) CH ₂ =CR ₁ -CO-OR ₂ (R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents Acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-hexyl acrylate, butyl acrylate, acrylic acid-2- represented by a hydroxyl group or a hydrocarbon group having a carbon number of 1 to 20) Ethylhexyl ester, 4-hydroxybutyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, n-hexyl methacrylate , lauryl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, hydroxypropyl methacrylate, and the like. Further examples are acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, N-methylol acrylamide, N-alkyl alcohol acrylamide, diacetone acrylamide, diacetone methacryl Indoleamine, acrolein, methacrolein, glycidyl methacrylate, etc. are used as reactive monomers. In the present invention, those which are obtained by copolymerizing these monomers in accordance with a usual method to form a designated acrylic resin can be used.

In order to improve the toughness, stretchability, heat resistance, moist heat resistance, and weather resistance of the easy-adhesive layer (3), the non-light-receiving side sealing material (IV) and the present invention are used using an adhesive containing a crosslinking agent. When the solar cell back surface protective sheet (V) is bonded to form a solar cell module, it is preferable to crosslink the easy-adhesive layer (3) containing a crosslinking agent on the outermost surface of the solar cell back surface protective sheet (V). For example, when a polyester resin, a urethane resin, or an acrylic resin exemplified above is used in the easy-adhesive layer (3), the resin has a hydroxyl group, a carboxyl group, a sulfonyl group, a phosphonium group, an isocyanate. The reaction point of a group, an epoxy group or the like is preferred.

As the crosslinking agent, a polyisocyanate compound, a polycyanate compound, a polyglycidyl compound, a polyaziridine compound, or the like can be exemplified.

From the viewpoint of durability or coating stability, a curing agent having a functional group capable of reacting with a polyester-based or urethane-based resin having a hydroxyl group and an isocyanate-containing hydroxyl group is preferably an isocyanate compound. From the viewpoint of further improving durability, a polyisocyanate compound is preferred. Further, a blocked polyisocyanate compound can also be used. As the polyisocyanate compound, the same as the polyisocyanate compound exemplified as the crosslinking agent of the acrylic resin can be used.

As the hardener, in addition to the above polyisocyanate compound, a well-known oxazoline compound may be contained, for example, 2,5-dimethyl-2-oxazoline, 2,2-(1,4-dibutyl) Base)-bis(2-oxazoline) or anthraquinone compounds, such as diterpene isononanoate, diterpene sebacate, diammonium adipate.

The solar cell back surface protective sheet may be provided with a water vapor barrier layer in order to impart moisture resistance. The water vapor barrier layer is not particularly limited, and a metal foil or a vapor deposited layer of a metal oxide or a non-metal inorganic oxide can be exemplified.

As the metal foil, an aluminum foil, an iron foil, a zinc plate or the like can be used. Among them, an aluminum foil is preferable from the viewpoint of corrosion resistance, and a thickness of 10 μm to 100 μm is more preferable, and more preferably 20 μm to 50 μm. The laminate of the two can use various adhesives which have been known in the past.

The vapor deposition layer is provided on one surface of the plastic film (2). A single-sided vapor-deposited polyester film may be laminated with an interlayer adhesive layer interposed therebetween, or a single-sided vapor-deposited polyester film and another vapor-deposited film may be laminated via an interlayer adhesive layer.

For vaporized metal oxides or non-metal inorganic oxides, for example For example, an oxide of lanthanum, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, hafnium or the like can be used. Further, a fluoride of an alkali metal or an alkaline earth metal or the like can also be used. These can be used alone or in combination. These metal oxides or non-metal inorganic oxides can be deposited by a PVD method such as vacuum vapor deposition, ion plating, sputtering, or the like, or a CVD method such as plasma CVD or microwave CVD.

The water vapor barrier layer may be a laminate of two or more layers of the barrier layer in order to provide electrical insulation or water vapor barrier properties.

For the method of providing the weather resistant flame-retardant resin layer (1) or the easy-adhesive layer (3) on the plastic film (2) or the water vapor barrier layer, for example, a roll coater, a die coater, Coating methods such as roll coaters, bar coaters, gravure roll coaters, reverse roll coaters, dip coating methods, knife coaters, gravure coaters, micro gravure coaters, and angle wheel coaters, etc. a method of coating a weatherable flame retardant resin composition (1') or an easy-adhesive composition (3'), or a weather resistant flame retardant resin composition (1') or an easy-adhesive composition (3') The film is a method in which a plastic film (2) or a water vapor barrier layer (4) is bonded by a conventional lamination method such as a dry buildup method, an extrusion buildup method, or a heat buildup method.

Next, a method of manufacturing the solar cell back surface protective sheet of the present invention will be described. 2A is a schematic cross-sectional view showing an example of a solar cell back surface protective sheet of the present invention in which a weather resistant flame-retardant resin layer (1), a plastic film (2), and an easy-adhesive layer (3) are laminated. The solar cell back surface protective sheet of the present invention may have a water vapor barrier layer (4), an interlayer adhesive layer (5), and the like. For example, FIG. 2B shows a laminate of a weather-resistant flame-retardant resin layer (1), a water vapor barrier layer (4), an interlayer adhesive layer (5), a plastic film (2), and an easy-adhesive layer (3). Invented solar cell backside protection A schematic cross-sectional view of an example of a sheet. Moreover, Fig. 2C shows a weather-resistant flame-retardant resin layer (1), a plastic film (2), an interlayer adhesive layer (5), a water vapor barrier layer (4), and an easy-adhesive layer (3). A schematic cross-sectional view of an example of a solar cell back protective sheet of the invention.

Next, a method of manufacturing the solar cell module of the present invention will be described. The solar cell module of the present invention is obtained by the solar cell surface sealing sheet (I) located on the light receiving surface side of the solar cell, the sealing material layer (II) on the light receiving surface side of the solar cell, and the solar cell element. (III), a sealing material layer (IV) on the non-light-receiving surface side of the solar cell, and a solar cell back surface protective sheet of the present invention as a detailed configuration layer, and the solar cell back surface protective sheet constituting the present invention The weather-resistant flame-retardant resin layer (1) is laminated in such a manner as to be farthest from the solar cell surface sealing sheet (I). In other words, the solar cell inner sealing sheet is laminated on the non-light-receiving side sealing material layer (IV) by being connected to the easy-adhesive layer (3) constituting the solar cell back surface protective sheet of the present invention, and the present invention can be obtained. Solar battery module. When the non-light-receiving side sealing material layer (IV) and the solar cell back surface protective sheet are laminated, the two are brought into contact under reduced pressure, and then it is preferable to carry out the superposition under heating and pressure. The easy adhesive layer (3) is in the case of thermosetting, and it can be returned to normal pressure and then placed under high temperature conditions to perform hardening of the easy adhesive layer (3).

[Examples]

Hereinafter, the present invention will be described in further detail by way of examples. In the examples, the parts represent parts by weight and the % means % by weight. The physical properties of the acrylic resin solution are shown in Table 1.

<Acrylic resin solution B1>

40 parts of methyl methacrylate, 28 parts of n-butyl methacrylate, and 2-ethylhexyl methacrylate 28 were placed in a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube. 2 parts of 2-hydroxyethyl methacrylate, 2 parts of pentamethylbispiperidinyl methacrylate, 100 parts of toluene, and the temperature is raised to 80 ° C while stirring under a nitrogen atmosphere, and 0.15 parts of azo double is added. Isobutyronitrile was subjected to polymerization for 2 hours. Secondly, 0.07 parts of azobisisobutyronitrile was added to further carry out polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added for further polymerization for 2 hours to obtain a weight average. The acrylic resin solution B1 having a molecular weight of 73,000, a hydroxyl value of 7.9 (mgKOH/g), an acid value of 0 (mgKOH/g), a Tg of 37 ° C, and a solid content of 50%. Further, the weight average molecular weight, the glass transition temperature, the acid value, and the hydroxyl value were measured in the manner described below.

<Measurement of Weight Average Molecular Weight (Mw)>

The measurement of Mw uses GPC (gel permeation chromatography). GPC is a liquid chromatography method in which a substance dissolved in a solvent (THF; tetrahydrofuran) is separated and quantified by a difference in molecular size, and the weight average molecular weight (Mw) is determined in terms of polystyrene.

<Measurement of glass transition temperature (Tg)>

The measurement of the glass transition temperature is obtained by differential scanning calorimetry (DSC). Specifically, a sample of about 10 mg was weighed in an aluminum pan, and was placed in a DSC apparatus (reference: an aluminum pan of the same type in which the sample was not placed), heated at a temperature of 300 ° C for 5 minutes, and then quenched by using liquid nitrogen to - 120 ° C. Thereafter, the temperature was raised at 10 ° C /min, and the glass transition temperature (Tg) (unit: ° C) was calculated from the obtained DSC chart. Further, the sample for Tg measurement was obtained by heating the above-mentioned acrylic resin solution at 150 ° C. 15 minutes and dry.

<Measurement of acid value (AV)>

A sample (resin solution: about 50%) of about 1 g was accurately weighed in a co-plug flask, and 100 ml of a toluene/ethanol (capacity ratio: toluene/ethanol = 2/1) mixture was added thereto to dissolve. Among them, a phenolphthalein test solution was added as an indicator for 30 seconds. Thereafter, the solution was titrated with a 0.1 N alcoholic potassium hydroxide solution until the solution was reddish. The acid value is obtained by the following formula. The acid value is the value of the dry state of the resin (unit: mgKOH/g).

Acid value (mgKOH/g) = {(5.611 × a × F) / S} / (nonvolatile content concentration / 100)

Among them, S: the amount of sample taken (g)

a: consumption of 0.1N alcoholic potassium hydroxide solution (ml)

F: the price of 0.1N alcoholic potassium hydroxide solution

<Measurement of hydroxyl number (OHV)>

A sample (resin solution: about 50%) of about 1 g was accurately weighed in a co-plug flask, and 100 ml of a toluene/ethanol (capacity ratio: toluene/ethanol = 2/1) mixture was added thereto to dissolve. Further, 5 ml of an acetylation agent (25 g of acetic anhydride was dissolved in pyridine to prepare a solution having a capacity of 100 ml) was added, and the mixture was stirred for about 1 hour. A phenolphthalein test solution was added thereto as an indicator for 30 seconds. Thereafter, the solution was titrated with a 0.1 N alcoholic potassium hydroxide solution until the solution was reddish. The hydroxyl value is obtained by the following formula. The hydroxyl value is taken as the value of the dry state of the resin (unit: mgKOH/g).

Hydroxyl valence (mgKOH/g) = [{(b-a) × F × 28.25} / S] / (nonvolatile content concentration / 100) + D

among them S: The amount of sample taken (g)

a: consumption of 0.1N alcoholic potassium hydroxide solution (ml)

b: consumption of 0.1N alcoholic potassium hydroxide solution in blank experiment (ml)

F: the price of 0.1N alcoholic potassium hydroxide solution

D: acid value (mgKOH/g)

<Acrylic resin solution B2>

48 parts of isodecyl methacrylate, 48 parts of n-butyl methacrylate, and 2 parts of 4-hydroxybutyl acrylate were placed in a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube. 2 parts of pentamethylbispiperidinyl methacrylate and 100 parts of toluene were heated to 80 ° C while stirring under a nitrogen atmosphere, and 0.15 parts of azobisisobutyronitrile was added thereto to carry out polymerization for 2 hours, followed by addition. 0.07 parts of azobisisobutyronitrile was further subjected to polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours to obtain a weight average molecular weight of 67,000 and a hydroxyl value of 8.2 (mgKOH/g). An acrylic resin solution B2 having an acid value of 0 (mgKOH/g), a Tg of 29 ° C, and a solid content of 50%.

<Acrylic resin solution B3>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 19 parts of methyl methacrylate, 77 parts of n-butyl methacrylate, and 2 parts of 2-hydroxyethyl methacrylate were placed. 2 parts of pentamethylbispiperidinyl methacrylate and 100 parts of toluene were heated to 80 ° C while stirring under a nitrogen atmosphere, and 0.13 parts of azobisisobutyronitrile was added thereto for polymerization for 2 hours, followed by addition. 0.07 parts of azobisisobutyronitrile was further subjected to polymerization for 2 hours, and then 0.07 parts of azo was further added. The diisobutyronitrile was further subjected to a polymerization reaction for 2 hours to obtain an acrylic acid having a weight average molecular weight of 90,000, a hydroxyl value of 8.1 (mgKOH/g), an acid value of 0 (mgKOH/g), and a solid content of 50% by weight of 45 °C. Resin solution B3.

<Acrylic resin solution B4>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 43 parts of methyl methacrylate, 52 parts of n-butyl methacrylate, and 3 parts of 2-hydroxyethyl methacrylate were placed. 2 parts of pentamethylbispiperidyl methacrylate (FANCRYL FA-711MM, manufactured by Hitachi Chemical Co., Ltd.) and 100 parts of toluene were heated to 80 ° C while stirring under a nitrogen atmosphere, and 0.15 parts of azobis was added. The butyronitrile was subjected to polymerization for 2 hours, and then 0.07 parts of azobisisobutyronitrile was further added for further polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added for further polymerization for 2 hours to obtain a weight average molecular weight of 86,000, an acrylic resin solution B4 having a hydroxyl value of 12.2 (mgKOH/g), an acid value of 0 (mgKOH/g), and a solid content of 50% at 7 °C.

<Acrylic resin solution B5>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 60 parts of methyl methacrylate, 35 parts of n-butyl methacrylate, and 2 parts of 4-hydroxybutyl acrylate were placed. 2 parts of pentamethylbispiperidinyl acrylate, 1 part of methacrylic acid, 100 parts of toluene, heated to 80 ° C while stirring under a nitrogen atmosphere, and 0.15 parts of azobisisobutyronitrile was added to carry out polymerization reaction 2 After the addition, 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours to obtain a weight average molecular weight of 75,000 and a hydroxyl value of 7.9. (mgKOH/g) An acrylic resin solution B5 having an acid value of 8 (mgKOH/g) and a solid content of 50% at 61 °C.

<Acrylic resin solution B6>

Into a four-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 53 parts of cyclohexyl methacrylate, 41 parts of n-butyl methacrylate, and 4 parts of 4-hydroxybutyl acrylate were placed. 2 parts of pentamethylbispiperidinyl methacrylate and 100 parts of toluene were heated to 80 ° C while stirring under a nitrogen atmosphere, and 0.18 parts of azobisisobutyronitrile was added to carry out polymerization for 2 hours, followed by addition. 0.07 parts of azobisisobutyronitrile was further subjected to polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours to obtain a weight average molecular weight of 25,000 and a hydroxyl value of 8.0 (mgKOH/g). An acrylic resin solution B6 having an acid value of 0 (mgKOH/g) and a solid content of 50% at 41 °C.

<Acrylic resin solution B7>

19 parts of methyl methacrylate, 76 parts of n-butyl methacrylate, and 3 parts of 2-hydroxyethyl methacrylate were placed in a 4-neck flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube. 2 parts of pentamethylbispiperidinyl methacrylate and 100 parts of toluene were heated to 80 ° C while stirring under a nitrogen atmosphere, and 0.10 parts of azobisisobutyronitrile was added to carry out polymerization for 2 hours. 0.07 parts of azobisisobutyronitrile was further added for polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours to obtain a weight average molecular weight of 124,000 and a hydroxyl value of 11.9 (mgKOH/g). An acrylic resin solution B7 having an acid value of 0 (mgKOH/g) and a Tg of 50% solid content of 50%.

<Acrylic resin solution B8>

50 parts of methyl methacrylate, 46 parts of n-butyl acrylate, 4 parts of 2-hydroxyethyl methacrylate, and toluene 100 were placed in a 4-neck flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube. The mixture was heated to 80 ° C under stirring in a nitrogen atmosphere, and 0.15 parts of azobisisobutyronitrile was added to carry out polymerization for 2 hours. Next, 0.07 parts of azobisisobutyronitrile was added to further carry out polymerization for 2 hours. Further, 0.07 parts of azobisisobutyronitrile was further added for further polymerization for 2 hours to obtain a weight average molecular weight of 55,000, a hydroxyl value of 17.2 (mgKOH/g), an acid value of 0 (mgKOH/g), and a Tg of 19 °C. The acrylic resin solution B8 having a solid content of 50%.

<Acrylic resin solution B9>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 53 parts of cyclohexyl methacrylate, 19 parts of n-butyl methacrylate, and 2-ethylhexyl methacrylate were placed. 20 parts, 6 parts of 2-hydroxyethyl methacrylate, 2 parts of pentamethylbispiperidinyl methacrylate, 100 parts of toluene, and the temperature was raised to 80 ° C while stirring under a nitrogen atmosphere, and 0.15 parts of azo was added. Polymerization was carried out for 2 hours with diisobutyronitrile, followed by addition of 0.07 parts of azobisisobutyronitrile for further polymerization for 2 hours, and further addition of 0.07 parts of azobisisobutyronitrile was further carried out for 2 hours to obtain a weight. An acrylic resin solution B9 having an average molecular weight of 72,000, a hydroxyl value of 25.3 (mgKOH/g), an acid value of 0 (mgKOH/g), and a Tg of 18% solid content of 50%.

<Acrylic resin solution B10>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 32 parts of methyl methacrylate and n-butyl acrylate were placed. 32 parts, 32 parts of 2-ethylhexyl methacrylate, 2 parts of 4-hydroxybutyl acrylate, 2 parts of pentamethylbispiperidinyl methacrylate, 100 parts of toluene, and heated under stirring in a nitrogen atmosphere To 80 ° C, 0.15 parts of azobisisobutyronitrile was added to carry out polymerization for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added to further carry out polymerization for 2 hours, and then 0.07 parts of azobisisobutylate was further added. The nitrile was further subjected to polymerization for 2 hours to obtain an acrylic resin solution having a weight average molecular weight of 66,000, a hydroxyl value of 7.9 (mgKOH/g), an acid value of 0 (mgKOH/g), a Tg of -7 ° C, and a solid content of 50%. B10.

<Acrylic resin solution B11>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 36 parts of methyl methacrylate, 30 parts of n-butyl acrylate, and 30 parts of 2-ethylhexyl methacrylate were placed. 2 parts of 2-hydroxyethyl acrylate, 2 parts of pentamethylbispiperidinyl methacrylate, 100 parts of toluene, and the temperature is raised to 80 ° C while stirring under a nitrogen atmosphere, and 0.15 parts of azobisisobutyronitrile is added. The polymerization reaction was carried out for 2 hours, and then 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours to obtain a weight average molecular weight of 84,000. An acrylic resin solution B11 having a hydroxyl group value of 8.0 (mgKOH/g), an acid value of 0 (mgKOH/g), and a Tg of 50% solid content of -20 °C.

<Acrylic resin solution B12>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 62 parts of methyl methacrylate, 34 parts of n-butyl methacrylate, and 2 parts of 2-hydroxyethyl methacrylate were placed. 2 parts of pentamethylbispiperidinyl methacrylate and 100 parts of toluene under nitrogen atmosphere The temperature was raised to 80 ° C while stirring, 0.15 parts of azobisisobutyronitrile was added to carry out polymerization for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added to further carry out polymerization for 2 hours, and then added 0.07 parts. Nitrogen bisisobutyronitrile was further subjected to polymerization for 2 hours to obtain acrylic acid having a weight average molecular weight of 80,000, a hydroxyl value of 7.8 (mgKOH/g), an acid value of 0 (mgKOH/g), and a solid content of 70% by weight of 79 °C. Resin solution B12.

<Acrylic resin solution B13>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 80 parts of methyl methacrylate, 16 parts of n-butyl methacrylate, and 2 parts of 2-hydroxyethyl methacrylate were placed. 2 parts of pentamethylbispiperidinyl methacrylate and 100 parts of toluene were heated to 80 ° C while stirring under a nitrogen atmosphere, and 0.15 parts of azobisisobutyronitrile was added thereto to carry out a polymerization reaction for 2 hours. 0.07 parts of azobisisobutyronitrile was further added for polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours to obtain a weight average molecular weight of 84,000 and a hydroxyl value of 7.8 (mgKOH/g). An acrylic resin solution B13 having an acid value of 0 (mgKOH/g) and a solid content of 50% at 93 °C.

<Acrylic resin solution B14>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 40 parts of methyl methacrylate, 30 parts of n-butyl methacrylate, and 2-ethylhexyl methacrylate 28 were placed. 2 parts of 2-hydroxyethyl methacrylate and 100 parts of toluene were heated to 80 ° C while stirring under a nitrogen atmosphere, and 0.23 parts of azobisisobutyronitrile was added to carry out polymerization for 2 hours, followed by addition. 0.07 parts of azobisisobutyl The nitrile was further subjected to polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours to obtain a weight average molecular weight of 12,000, a hydroxyl value of 7.9 (mgKOH/g), and an acid value of 0 (mgKOH/ g) An acrylic resin solution B14 having a Tg of 50% solid content at 37 °C.

<Acrylic resin solution B15>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 40 parts of methyl methacrylate, 30 parts of n-butyl methacrylate, and 2-ethylhexyl methacrylate 28 were placed. 2 parts of 2-hydroxyethyl methacrylate and 100 parts of toluene were heated to 80 ° C while stirring under a nitrogen atmosphere, and 0.05 part of azobisisobutyronitrile was added to carry out polymerization for 2 hours, followed by addition. 0.05 parts of azobisisobutyronitrile was further polymerized for 2 hours, and 0.05 part of azobisisobutyronitrile was further added and polymerization was carried out for 2 hours to obtain a weight average molecular weight of 165,000 and a hydroxyl value of 7.9 (mgKOH/g). An acrylic resin solution B15 having an acid value of 0 (mgKOH/g) and a Tg of 50% solid content of 37 °C.

<Acrylic resin solution B16>

In a four-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 20 parts of methyl methacrylate, 80 parts of n-butyl methacrylate, and 100 parts of toluene were placed, and the mixture was placed under a nitrogen atmosphere. The temperature was raised to 80 ° C while stirring, 0.15 parts of azobisisobutyronitrile was added to carry out polymerization for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added to further carry out polymerization for 2 hours, and then 0.07 parts of azo was further added. The diisobutyronitrile was further subjected to polymerization for 2 hours to obtain a weight average molecular weight of 80,000, a hydroxyl value of 0 (mgKOH/g), and an acid value of 0 (mgKOH/g). The Tg is an acrylic resin solution B16 having a solid content of 50% at 34 °C.

<Acrylic resin solution B17>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 22 parts of methyl methacrylate, 77.5 parts of n-butyl methacrylate, 0.5 parts of 4-hydroxybutyl acrylate, and toluene were placed. 100 parts, the temperature was raised to 80 ° C while stirring under a nitrogen atmosphere, 0.15 parts of azobisisobutyronitrile was added to carry out polymerization for 2 hours, and then 0.07 parts of azobisisobutyronitrile was added to further carry out polymerization reaction 2 In an hour, 0.07 parts of azobisisobutyronitrile was further added for further polymerization for 2 hours to obtain a weight average molecular weight of 73,000, a hydroxyl value of 1.9 (mgKOH/g), an acid value of 0 (mgKOH/g), and a Tg of 35. An acrylic resin solution B17 having a solid content of 50% at °C.

<Acrylic resin solution B18>

In a 4-necked flask equipped with a cooling tube, a stirring device, a thermometer, and a nitrogen introduction tube, 32 parts of methyl methacrylate, 46 parts of n-butyl methacrylate, and 2-ethylhexyl methacrylate 10 were placed. 10 parts of 2-hydroxyethyl methacrylate, 2 parts of pentamethylbispiperidinyl methacrylate, 100 parts of toluene, and the temperature is raised to 80 ° C while stirring under a nitrogen atmosphere, and 0.15 parts of azo double is added. Polymerization was carried out for 2 hours with isobutyronitrile, followed by addition of 0.07 parts of azobisisobutyronitrile for further polymerization for 2 hours, and further addition of 0.07 parts of azobisisobutyronitrile for further polymerization for 2 hours to obtain a weight average An acrylic resin solution B18 having a molecular weight of 71,000, a hydroxyl value of 39.4 (mgKOH/g), an acid value of 0 (mgKOH/g), and a Tg of 30% solid content of 50%.

<Acrylic resin solution B19>

4 with cooling tube, stirring device, thermometer, nitrogen inlet tube In the mouth flask, 22 parts of methyl methacrylate, 46 parts of n-butyl methacrylate, 10 parts of 2-ethylhexyl methacrylate, 20 parts of 2-hydroxyethyl methacrylate, and methyl group were placed. 2 parts of pentamethylbispiperidinyl acrylate and 100 parts of toluene were heated to 80 ° C while stirring under a nitrogen atmosphere, 0.15 parts of azobisisobutyronitrile was added to carry out polymerization for 2 hours, and then 0.07 parts were added. The azobisisobutyronitrile was further subjected to polymerization for 2 hours, and further 0.07 parts of azobisisobutyronitrile was further added to carry out polymerization for 2 hours to obtain a weight average molecular weight of 65,000, a hydroxyl value of 80.2 (mgKOH/g), and an acid. An acrylic resin solution B19 having a valence of 0 (mgKOH/g) and a solid content of 30% at 33 °C.

<crosslinking agent solution>

The trimer of hexamethylene diisocyanate was diluted with ethyl acetate to obtain a crosslinking agent solution of a 70% solids resin solution.

<Preparation of weather resistant flame retardant resin solution (1~36, 101, 102)>

The phosphorus-based flame retardant (A), the acrylic resin (B), the crosslinking agent, and the white pigment are mixed in a solid component composition ratio shown in Tables 2 and 3, and then dissolved in a 50/50 mixture of toluene/ethyl acetate. In the solvent, the solid content was made 50%. Further, after being dispersed by a paint shaker, a weather resistant flame retardant resin solution (1 to 36, 101, 102) was obtained.

Further, each symbol in the table is as follows.

Phosphorus-based flame retardant A1: Exolit OP930 (aluminum trisuccinate, manufactured by Clariant)

Phosphorus-based flame retardant A2: Exolit OP1230 (aluminum trisuccinate, manufactured by Clariant)

Phosphorus-based flame retardant A3: Exolit OP1312 (mixture of aluminum trisuccinate and melamine phosphate, manufactured by Clariant)

Phosphorus-based flame retardant A4: SPB-100 (phenoxycyclotriphosphazene, manufactured by Otsuka Chemical Co., Ltd.)

Phosphorus-based flame retardant A5: SPH-100 (4-hydroxyphenoxycyclotriphosphazene, manufactured by Otsuka Chemical Co., Ltd.)

Phosphorus-based flame retardant A6: FP-300 (4-cyanophenoxycyclotriphosphazene, manufactured by Fushimi Pharmaceutical Co., Ltd.)

Phosphorus-based flame retardant A7: PHOSMEL100 (melamine phosphate, manufactured by Hitachi Chemical Co., Ltd.)

Phosphorus-based flame retardant A8: PHOSMEL200 (melamine phosphate dimer, manufactured by Hitachi Chemical Co., Ltd.)

Phosphorus-based flame retardant A9: ammonium polyphosphate

Phosphorus-based flame retardant A10: Triphenyl phosphate (made by Daiba Chemical Industry Co., Ltd.)

Non-phosphorus flame retardant A11: STABIACE MC-55 (melamine cyanurate, manufactured by Nippon Chemical Industry Co., Ltd.)

Non-phosphorus flame retardant A12: aluminum hydroxide

Halogen-based flame retardant A13: Fire Cut FCP-83D (decabromodiphenyl oxide, manufactured by Suyu Chemical Co., Ltd.)

TIPAQUE CR-97: Titanium oxide for white pigments made by Ishihara Industries

<Production of weather-resistant flame retardant film (1~36, 101, 102)>

The weather-resistant flame-retardant resin solution (1 to 36, 101, 102) is applied to the peeled polyethylene terephthalate (hereinafter referred to as SP-PET) by an applicator. The solvent was evaporated to obtain a coating film of 30 μm, and peeled off from SP-PET to prepare a weather-resistant flame-retardant film.

<Combustibility measurement: UL test>

Thickness is evaluated by the HB or V specification specified by UL-94 30μm weather resistant flame retardant film (1~36, 101, 102).

<<HB specification>> A test piece in which a strip-shaped test piece is placed horizontally, and one end portion is in contact with the fire of the burner to cause combustion, and the speed at which the combustion is performed is judged to be acceptable. In the case of a weather-resistant flame-retardant film having a thickness of 30 μm, the burning rate is 40 mm/min or less, or 75 mm/min or less, which is "qualified" for the HB test.

<<VSpecification>> Use 5 test pieces, and vertically touch the fire of the burner at the lower end of the supported strip test piece for 10 seconds, then let the burner fire leave from the test piece, if the flame is extinguished Immediately after touching the burner fire for 10 seconds, the burner's fire is removed.

The total flame burning duration after the first and second contact with the fire, the flame burning duration after the second fire contact and the flameless burning duration, and the five test pieces The total of the flame burning time and the presence or absence of the burning drop are determined. in particular:

V-0: no burning drop, the first and the second time together with the fire, the flame burning duration is less than 10 seconds, and the second time has the flame burning duration and no flame. The total burning time is less than 30 seconds. The total of the flame burning time of the test pieces of the other five sheets was within 50 seconds.

V-1: no burning drop, the first and the second time together with the fire, the flame burning duration is less than 30 seconds, and the second time has the flame burning duration and no flame. The total burning time is within 60 seconds. The total of the flame burning time of the test pieces of the other five sheets was less than 250 seconds.

V-2: Same as V-1 except that there is a burning drop.

In addition, because the HB specification and the V specification are different specifications, they cannot be directly compared. However, the V specification is stricter than the HB specification. Even if the HB specification is acceptable, the V specification may not be satisfied. The degree of V-2. Therefore, the good-to-noise sequence of the flame retardant is as shown below, and the more the left side is, the better.

>V-0>V-1>V-2>HB qualified>HB failed. The results are shown in Table 4.

<Production of solar cell back protective sheet 1>

Coronation treatment on both sides of a polyester film (Tetoron S, thickness 188 μm) was applied to the polyester adhesive "Dinareo VA-3020/HD-701" by a gravure coater (Toyo Ink SC Holdings) The company's system was prepared in the same manner as 100/7, the same as the following, and the solvent was dried to provide an interlayer adhesive layer having a coating amount of 10 g/m ² . The vapor deposition surface of the PET (Mitsubishi Resin, TECHBARRIER LX, thickness: 12 μm) was deposited by superposition of the interlayer adhesive layer. Thereafter, the laminate was cured at 50 ° C for 4 days to cure the interlayer adhesive layer to prepare a polyester film-vapor deposited PET laminate. Further, the vapor-deposited PET used was a vapor-deposited PET obtained by vacuum-depositing vermiculite.

Next, the weather-resistant flame-retardant resin solution 1 described in Table 2 was applied to the polyester film surface of the polyester film-vapor-deposited PET laminate, and the solvent was dried to provide a weather-resistant flame-retardant resin layer having a film thickness of 15 μm. Thereafter, the weathering-resistant flame-retardant resin layer was cured at 40 ° C for 3 days to prepare a weather-resistant flame-retardant resin layer-polyester film-evaporated PET laminate. Further, the solvent was dried by coating a polyester adhesive "Dinareo VA-3020/HD-701" on a vapor-deposited PET surface with a gravure coater, and the coating amount was 5 g/m ² (film thickness: 5 μm). The agent layer is used to fabricate the solar cell back protective sheet 1.

<Production of solar cell back protective sheet 2~36, 101, 102>

In the same manner as the solar cell back surface protective sheet 1, the solar cell back surface protective sheets 2 to 36, 101, and 102 were produced using the weather resistant flame retardant resin solutions 2 to 36, 101, and 102 shown in Tables 2 and 3.

<Production of solar cell back protective sheet 37>

In the weather-resistant flame-retardant resin solution 1, a solar cell back surface protective sheet 37 was produced in the same manner as the solar cell back surface protective sheet 1 except that a weather-resistant flame-retardant resin layer having a film thickness of 30 μm was provided.

<Production of solar cell back protective sheet 38>

In the weather-resistant flame-retardant resin solution 1, a solar cell back surface protective sheet 38 was produced in the same manner as the solar cell back surface protective sheet 1 except that a weather-resistant flame-retardant resin layer having a film thickness of 5 μm was provided.

<Production of solar cell back protective sheet 39>

A solar cell back surface protective sheet 39 which is a layer structure of a polyester film-vapor-deposited PET-adhesive layer is produced in the same manner as in the solar cell back surface protective sheet 1 except that the weather-resistant flame-retardant resin layer is not provided.

[Example 1]

The solar cell back surface protective sheet 1 was used to evaluate the cross-cut adhesion, the flammability, the moist heat resistance, and the weather resistance.

<Cross cutting adhesion measurement>

The cross-cut adhesiveness is applied to the weather-resistant flame-retardant resin layer of the solar cell back protective sheet 1 by a cutter to give a cross-shaped cut, and the cellophane tape peeling test is performed, and the residual coating film after peeling of the cellophane tape is visually observed, and the evaluation is performed. Adhesion of polyester film with weather resistant flame retardant resin layer .

○: The peripheral portion of the cut was not peeled off.

△: The tendency of a slight peeling was observed in the peripheral portion of the cut.

×: A clear peeling can be seen in the peripheral portion of the cut.

<Combustibility Measurement: Radiation Plate (RP) Test>

The flammability is subjected to a flame spread test (radiation plate test) according to ASTM-E162, the flame diffusion coefficient is calculated from the burning rate, and the heat release coefficient is calculated from the combustion temperature, and the product of the two is a flame spread index. The flame spread test means that the solar cell back protective sheet is ignited in the presence of a radiation plate at 600 ° C, the flame diffusion coefficient is obtained from the burning speed of the solar cell back protective sheet, and the heat release coefficient is obtained from the combustion temperature, and the flame spread is calculated. The method of evaluating the index. The specification value of UL1703 is 100 or less, and it is unacceptable when it exceeds 100.

○: below 50

△: 50 or more ~ less than 100

×: 100 or more ~ less than 150

××: 150 or more

<Heat and heat resistance test>

Moisture and heat resistance was evaluated by using a pressure cooker tester at a temperature of 105 ° C, a relative humidity of 100% RH, and a pressure of 2 atm. The cross-cut adhesion, yellowing degree, and flammability after leaving for 96 hours, 192 hours, and 288 hours were evaluated. (RP test). The cross-cut adhesion is evaluated based on the same method and criteria as described above. The yellowness is measured by the method described in JIS-Z8722, using a color difference meter CR-300 (manufactured by Konica Minolta Co., Ltd.), and measured by the side of the weather resistant flame-retardant resin layer of the solar cell back surface protective sheet 1 to L*a*b. * The color of the table indicates the Δb value at the time of evaluation.

○: Δb value is lower than 2

△: Δb value is 2 or more and lower than 4

×: Δb value is 4 or more and less than 10

××: Δb value is 10 or more

The flammability (RP test) was evaluated based on the same method and criteria as described above.

<Weatherability test>

The weather resistance was evaluated by the Eye Supa UV tester (manufactured by Iwasaki Electric Co., Ltd.) under the following conditions for cross-cut adhesion, yellowing degree, and film reduction in 10 cycles (i.e., after 120 hours).

(weatherability test conditions)

1) 63 ° C 70% 90mW / cm ² irradiation 4h

2) 70 ° C 90% static 4h

3) Shower for 10 seconds → condensation for 4 hours → shower for 10 seconds

4) The above 1), 2), and 3) were used as one cycle and 10 cycles were repeated (1 cycle, 12 hours. 10 cycles totaled 120 hours).

<film reduction>

A part of the surface of the weather-resistant flame-retardant resin layer of each test piece was protected by a weather-resistant tape, and the difference between the protected portion and the unprotected portion after 10 cycles was measured, and evaluated according to the following criteria.

○: film reduction is less than 1 μm

△: The film is reduced to 1 μm or more and less than 5 μm.

×: The film is reduced to 5 μm or more and less than 10 μm.

××: film reduction is 10 μm or more

[Examples 2 to 18, 101, 102], [Comparative Examples 1 to 21]

The solar cell back surface protection sheet 2 is used in the same manner as in the first embodiment. ~39, 101, and 102, evaluation of cross-cut adhesion, flammability, moist heat resistance, and weather resistance. The above results are shown in Tables 5 and 6.

As shown in Tables 5 and 6, Examples 1 to 18, 101, and 102 (weather-resistant flame retardant resin solutions 1 to 17, 101, and 102) exhibited excellent flame retardancy even in the flammability test by the flame spread test. . In other words, according to the present embodiment, the weather-resistant flame-retardant resin layer (1) having a thickness of 1/5 or less of the solar cell back surface protective sheet suppresses the burning (expansion) of the plastic film (2) which is the main constituent member, and the solar cell All of the back protective sheets are confirmed to meet the requirements of UL-1703. Moreover, after the heat and humidity resistance test or the weather resistance test, it exhibits excellent adhesion, and it is difficult to yellow when subjected to the heat and humidity resistance test or the weather resistance test. Even after the weather resistance test, the thickness of the coating film or film is not easily reduced. . Furthermore, even a flame spread test after damp heat can show good values. That is, the back surface protective sheets for solar cells of Examples 1 to 18 are impeccable back surface protective sheets for solar cells.

In particular, in Examples 1 to 6, 8 to 14, 17, 101, and 102 using aluminum phosphinate or phosphazene, the hydrophobicity of the weather-resistant flame-retardant resin layer (1) is high, and it is difficult to completely remove the phosphorus system. In Comparative Examples 1 to 3 of the fuel (A), a significant improvement in moisture heat resistance was observed. Further, as shown in Table 4, the weather-resistant flame-retardant films 1 to 17, 101, and 102 corresponding to Examples 1 to 17, 101, and 102 showed excellent results even in the flame retardancy test specified in UL-94.

On the other hand, the weather-resistant flame-retardant films 18 to 20 corresponding to Comparative Examples 1 to 3 did not contain the phosphorus-based flame retardant, and the specifications of the flame retardancy test specified in UL-94 were not satisfied as shown in Table 4, As shown in Table 6, the specification (UL-1703) of the flame spread test as a solar cell back protective sheet was not satisfied.

Further, in Comparative Examples 4 and 6 (using the weather-resistant flame-retardant resin solutions 21 and 23), ammonium polyphosphate was used as the phosphorus-based flame retardant, and in Comparative Example 5 (using the weather-resistant flame-retardant resin solution 22), triphenyl was used. Phosphate as a phosphorus-based flame retardant, which can be seen from the flammability evaluation of the flame spread test in the initial stage. fruit. However, large deterioration was observed in the heat and humidity resistance test. In other words, in the heat and humidity resistance test, phosphoric acid which is a strong acid produced by hydrolysis of ammonium polyphosphate or triphenyl phosphate causes deterioration and embrittlement of the weather-resistant flame-retardant resin layer (1) or the plastic film (2). Since the flame retardancy of the embrittled solar cell back protective sheet is also lowered, the result is that the flame spread test is not satisfied.

Further, in Comparative Examples 7 and 8 (using the weather-resistant flame-retardant resin solutions 24 and 25), melamine cyanurate or aluminum hydroxide was used as a flame retardant, and the weather resistance and the moist heat resistance were not so large. However, unlike the formation of a phosphorus-based flame retardant and the occurrence of flame retardancy, melamine cyanurate and aluminum hydroxide do not form a carbonized film, and the flame retardant effect is not sufficient. In addition, when the blending amount of such a flame retardant is increased in order to improve the flame retardancy, the weather resistant resin (1) is relatively small, and the weather resistant flame retardant resin layer (1) is difficult to manufacture by itself. It can be predicted to have a great influence on weather resistance, heat and humidity resistance and the like.

Further, in Comparative Example 9 (using the weather-resistant flame-retardant resin solution 26), decabromodiphenyl ether which is a halogenated flame retardant was used as a flame retardant, and there was no problem in flame retardancy. However, when subjected to a weathering test or a damp heat test, it is not suitable for use as a component of a solar cell module, which is often exposed to light or moist heat due to significant yellowing.

Further, in Comparative Examples 10 and 11 (using the weather-resistant flame-retardant resin solutions 27 and 28), since the Tg was too low, the coating film was weak and the heat resistance was not sufficient, so that the flame retardancy was poor, and the film thickness was evaluated in the weather resistance test. Will decrease.

In Comparative Examples 12 and 13 (using the weather-resistant flame-retardant resin solutions 29 and 30), when the Tg was too high, the adhesion and the flame retardancy were lowered during the damp heat test.

In Comparative Example 14 (using the weather-resistant flame-retardant resin solution 31), the molecular weight was too low, the film hardness was insufficient, and the moist heat resistance and the weather resistance were insufficient. Comparative Example 15 (Using the weather-resistant flame retardant resin solution 32) was a molecular weight. Too high and plastic The wettability of the film is poor, and when it is subjected to the damp heat test, the adhesion and the flame retardancy are lowered.

Comparative Examples 16 and 17 (using the weather-resistant flame-retardant resin solutions 33 and 34) did not have a hydroxyl group or a small amount of hydroxyl groups, and the curing was not sufficiently performed. After the damp heat test, it was not necessary to say that the weather resistance test was performed before the test. The state, all performances led by adhesion are significantly poor.

In Comparative Examples 18 and 19 (using the weather-resistant flame-retardant resin solutions 35 and 36), the hydroxyl group was excessively priced and the hardening shrinkage was large, and when the damp heat test was performed, the adhesion and the flame retardancy were remarkably lowered.

Since the adhesion of the plastic film of the weather-resistant flame-retardant resin layer is deteriorated, the flame retardancy of the solar cell back protective sheet cannot be maintained, so that not only the type or amount of the phosphorus-based flame retardant (A) but also the acrylic resin It is extremely important that the Tg, molecular weight, and hydroxyl value of (B) are within the scope of the present invention.

In Comparative Example 20, the weather-resistant flame-retardant resin solution 1 was used in the same manner as in Example 1, but the film thickness t of the weather-resistant flame-retardant resin layer (1) was too thin compared with the total film thickness of the solar cell back surface protective sheet. Therefore, there is no flame retardant effect.

Since Comparative Example 21 (using the weather-resistant flame-retardant resin film 39) does not have the weather-resistant flame-retardant resin layer (1), the plastic film (2) is exposed on the surface, and the burnability is also poor, in addition to the poor weather resistance. .

Further, in Example 13, since the hydroxyl value was slightly higher, the adhesion to the substrate after damp heat tends to be lowered, and the flame retardancy tends to be slightly lowered. Further, in Example 15, since the total phosphorus concentration was small, the flame retardancy in the flame spread test was slightly inferior, and in Example 16, the total amount of the phosphorus-based flame retardant (A) was relatively large, and the total amount of the acrylic resin (B) was relatively large. Reduced, so it can be seen that weather resistance or heat and humidity resistance is reduced. Further, in Examples 101 and 102, the amount of the phosphorus-based flame retardant was small, and the flame retardancy in the flame spread test was slightly inferior.

The application is based on the priority of Japanese Patent Application No. 2011-170505, filed on Aug. 3, 2011, and the Japanese Patent Application No. 2012-096934, filed on Apr. 20, 2012. Into this article.

I‧‧‧Solar cell surface sealing sheet on the light-receiving side of solar cells

II‧‧‧ Sealant layer on the light-receiving side of solar cells

III‧‧‧Solar battery components

IV‧‧‧ Sealant layer on the non-light-receiving side of solar cells

V‧‧‧Solar battery back protection sheet

1‧‧‧ weather resistant flame retardant resin layer

2‧‧‧Plastic film

3‧‧‧ adhesive layer

4‧‧‧Water Vapor Barrier

5‧‧‧Interlayer adhesive layer

Fig. 1 is a schematic cross-sectional view showing a module for a solar cell of the present invention.

Fig. 2A is a schematic cross-sectional view showing an example of a solar cell back surface protective sheet of the present invention.

Fig. 2B is a schematic cross-sectional view showing an example of a solar cell back surface protective sheet of the present invention.

Fig. 2C is a schematic cross-sectional view showing an example of a solar cell back surface protective sheet of the present invention.

Claims (5)

A solar cell back surface protective sheet comprising a weather resistant flame-retardant resin layer (1) having a film thickness t (μm), a plastic film (2), and an adhesive layer (3), wherein One surface of the solar cell back surface protective sheet is composed of the weather resistant flame-retardant resin layer (1), and the other surface of the solar cell back surface protective sheet is composed of the above-mentioned easy-adhesive layer (3), and the weather-resistant flame-retardant resin layer ( 1) a phosphorus-based flame retardant (A) and an acrylic resin (B), wherein the phosphorus-based flame retardant (A) is selected from the group consisting of a phosphazene compound, a phosphinic acid compound, and (poly)phosphoric acid melamine In the group, the acrylic resin (B) has a glass transition temperature of 0 to 70 ° C, a weight average molecular weight of 15,000 to 150,000, a hydroxyl value of 2 to 30 (mgKOH/g), and the weather resistant flame retardant resin layer (1). The film thickness t is 2.5 to 20% of the total film thickness of the solar cell back protective sheet, and the total phosphorus concentration of the phosphorus-based flame retardant (A) in the weather resistant flame-retardant resin layer (1) is 2.1 to 14.2 by weight. %. The solar cell back surface protective sheet of claim 1, wherein the acrylic resin (B) has a hydroxyl value of 5 to 20 (mgKOH/g). The solar cell back surface protective sheet according to claim 1 or 2, wherein the weather resistant flame-retardant resin layer (1) contains 20 to 50% by weight of the phosphorus-based flame retardant (A). The solar cell back surface protective sheet according to claim 1 or 2, wherein the total phosphorus concentration of the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is 3 to 10% by weight. A solar cell module having a light receiving by a solar cell a solar cell surface sealing sheet (I) on the surface side, a sealing material layer (II) on the light receiving surface side of the solar cell, a solar cell element (III), and a sealant layer on the non-light-receiving surface side of the solar cell (IV) And a solar cell module obtained by arranging the solar cell back surface protective sheet (V) according to any one of claims 1 to 4, wherein the non-light-receiving side sealant layer (IV) is adjacent to the non-light-receiving side sealant layer (IV), wherein The weather-resistant flame-retardant resin layer (1) constituting the solar cell back surface protective sheet is located farthest from the solar cell surface sealing sheet (I).