JP2008004839A - Film for solar cell back surface protection sheet, and back surface protection sheet for solar cell module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a back protection sheet film of a solar cell which has a good anti-hydrolysis property, and does not turn yellow even in long-term outdoor use, and is excellent in weather resistance. <P>SOLUTION: The back protection sheet film is composed of a polyester resin containing benzooxazine, where the benzooxazine content is 0.3-2 mass%, the oligomer content of the polyester resin is 0.1-0.6 mass%, and the carboxyl terminal group amount of the resin is 3-15 equivalent/ton. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a film for a solar cell back surface protective sheet having excellent weather resistance.

In recent years, solar cells as a clean energy source have attracted attention due to the growing awareness of environmental issues.
Solar cell elements are often made using a single crystal silicon substrate or a polycrystalline silicon substrate, so the solar cell elements are vulnerable to physical shock, and it is necessary to protect them from rain when solar cells are installed outdoors. There is. Moreover, since the electrical output generated by one solar cell element is small, it is necessary to connect a plurality of solar cell elements in series and parallel so that a practical electrical output can be taken out. For this reason, a solar cell module is usually manufactured by connecting a plurality of solar cell elements and enclosing them with a transparent substrate and a filler. In general, a solar cell module is manufactured by using a lamination method or the like in which a transparent front substrate, a filler, a solar cell element, a filler, a back surface protection sheet, and the like are sequentially laminated, and these are vacuum-sucked and thermocompression bonded.

  Since the solar cell is often used outdoors due to its nature, the members constituting the solar cell module are required to have high durability. Especially, the back surface protection sheet used for the solar cell module is mainly required to have excellent mechanical strength and durability such as weather resistance and hydrolysis resistance in order to protect the back surface of the solar cell module. Yes. At present, as such a back surface protection sheet for a solar cell module, a plastic base material having excellent strength characteristics is most commonly used, and in addition, a metal plate or the like is also used. Among them, a composite film of a fluorine resin film and a metal foil is widely used (Patent Document 1).

  Since the composite film with the metal foil has a high water vapor barrier property, it is useful for protecting solar cells that are easily deteriorated by water vapor. However, such a composite film of a fluororesin film and a metal foil may be short-circuited when a scratch or the like is generated by an external force, and the back surface protection sheet for the solar cell module may be short-circuited. -Further improvement is desired as a material to be used for G. In addition, since a metal foil is used, there is room for improvement in the short circuit resistance, which is a main characteristic, as a packaging material for an electronic device that is assumed to have a relatively high voltage load such as a solar cell module. Further, depending on the disposal / treatment method, the fluororesin film is feared to have a high load on the environment, and it is pointed out that it is not optimal as a solar cell module member that advocates clean energy.

Under such circumstances, Patent Document 2 describes a solar cell module comprising a two- to three-layer resin film laminate of a hydrolysis-resistant film, a resin film coated with a metal oxide, and a white resin film. A back surface protection sheet is disclosed. The back surface protection sheet for a solar cell module having such a configuration has durability such as hydrolysis resistance, and is a short circuit resistance problem that has been one of the problems of the conventional back surface protection sheet for solar cell modules. There is an advantage in that it can be solved.
On the other hand, regarding the problem of weather resistance, the back surface protection sheet for solar cell modules produced using a hydrolysis-resistant polyester film as a hydrolysis-resistant film still has a problem of yellowing during long-term use outdoors. .

JP 2000-174296 A Japanese Patent Laid-Open No. 2002-100788

  The present invention has been made in view of the above problems, and has a good hydrolysis resistance, and does not yellow even when used outdoors for a long time. The main purpose is to provide.

In order to achieve the above object, the present invention provides a film for protecting a back surface of a solar cell comprising a polyester-based resin containing a benzoxazine represented by the following chemical formula, wherein the content of the benzoxazine is 0.3 to 2% by mass. And the polyester-based resin has an oligomer content of 0.1 to 0.6% by mass and a carboxyl end group content of 3 to 15 equivalents / ton. A sheet film is provided.

According to the present invention, when the content of the benzoxazine is 0.3 to 2% by mass, a film for solar cell back surface protection sheet excellent in weather resistance that does not yellow even when used outdoors for a long time is obtained. be able to.
Moreover, according to this invention, since the said benzoxazine has high compatibility with the said polyester-type resin, it can obtain the film for solar cell back surface protection sheets which has desired weather resistance, without bad effects, such as a bleed-out.

  Furthermore, the polyester-based resin has an oligomer content of 0.1 to 0.6% by mass and a carboxyl terminal group content of 3 to 15 equivalents / ton, so that the solar cell has excellent hydrolysis resistance. The film for back surface protection sheets can be obtained.

This invention provides the back surface protection sheet for solar cell modules characterized by having the said film for solar cell back surface protection sheets, and the resin film laminated | stacked on the said film for solar cell back surface protection sheets.

According to this invention, the solar cell module back surface protection sheet excellent in weather resistance can be obtained by using the film for solar cell back surface protection sheets of the said invention.
In addition, by adding a color additive or the like to the resin film, incident sunlight can be reflected to improve the power generation efficiency of the solar cell element, and design properties can be imparted.

In the said invention, it is preferable to have a gas barrier film which consists of a base film and the gas barrier layer formed in the at least single side | surface of the said base film between the said film for solar cell back surface protection sheets, and the said resin film. . Moreover, in the said invention, you may have 2 or more of such gas barrier films.
By having the gas barrier film between the film for solar cell back surface protection sheet and the resin film, the moisture resistance of the back surface protection sheet for solar cell module of the present invention can be improved. Therefore, for the solar cell module of the present invention This is because the durability of the solar cell module using the back surface protection sheet can be improved.

  INDUSTRIAL APPLICABILITY The present invention has an effect of providing a film for protecting a back surface of a solar cell that has good hydrolysis resistance, does not yellow even when used outdoors for a long time, and has excellent weather resistance.

The present invention relates to a film for protecting a back surface of a solar cell excellent in weather resistance and a back surface protecting sheet for a solar cell module using the same. Hereinafter, the film for solar cell back surface protection sheet of this invention and the solar cell backsheet using the same are demonstrated in detail.

A. First, the film for solar cell back surface protection sheet of the present invention will be described. The film for solar cell back surface protective sheet of the present invention is a film for solar cell back surface protective sheet made of a polyester resin containing benzoxazine represented by the following chemical formula, and the content of the benzoxazine is 0.3 to 2 mass. And the polyester-based resin has an oligomer content of 0.1 to 0.6% by mass and a carboxyl end group content of 3 to 15 equivalents / ton. .

The film for protecting a back surface of a solar cell of the present invention contains the above-mentioned benzoxazine in a range of 0.3 to 2% by mass, so that it does not turn yellow even when used outdoors for a long time. A protective sheet film can be obtained.
Moreover, since the benzoxazine used for this invention has high compatibility with a polyester-type resin, it can be set as the film for solar cell back surface protection sheets which has desired weather resistance, without bad effects, such as a bleed-out.
Furthermore, the film for a solar cell back surface protective sheet has an oligomer content of 0.1 to 0.6% by mass, and further comprises a polyester-based resin having a carboxyl end group content of 3 to 15 equivalents / ton, A film for protecting a back surface of a solar cell excellent in hydrolysis resistance can be obtained.

  The film for solar cell back surface protection sheet used for this invention consists of a polyester-type resin containing a benzoxazine. Hereinafter, the benzoxazine and the polyester resin constituting the film for a solar cell back surface protective sheet of the present invention will be described.

(1) Benzoxazine The benzoxazine contained in the film for solar cell back surface protection sheets used for this invention is demonstrated. The benzoxazine used in the present invention is characterized by being contained in an amount of 0.3 to 2% by mass in the solar cell back surface protective sheet film. In this invention, the film for solar cell back surface protection sheets of this invention can be made into the thing excellent in the weather resistance which is not yellowed by long-term use outdoors by containing benzoxazine with such content.

  The content of benzoxazine used in the present invention is in the range of 0.3 to 2% by mass as described above. In the present invention, the content of benzoxazine is 0.4 to 1.5%. It is preferably in the range of mass%, and particularly preferably in the range of 0.6 to 1.2 mass%. In the present invention, the content of benzoxazine is defined in this way. If the content is less than the above range, the weather resistance is not sufficient, and there is a problem that yellowing occurs during long-term outdoor use. This is because if the content exceeds the above range, the weather resistance does not change and the cost increases.

(2) Polyester resin Next, the polyester resin constituting the film for solar cell back surface protective sheet used in the present invention will be described. The polyester resin used in the present invention is characterized by comprising a polyester resin having an oligomer content of 0.1 to 0.6% by mass and a carboxyl terminal group content of 3 to 15 equivalents / ton. Is. In this invention, the film for solar cell back surface protection sheets of this invention can be made excellent in hydrolysis resistance by using the polyester-type resin which has such oligomer content and the amount of carboxyl terminal groups.

  As described above, the polyester resin used in the present invention has an oligomer content of 0.1 to 0.6% by mass and a carboxyl terminal group content of 3 to 15 equivalents / ton. As content, it is preferable to exist in the range of 0.1-0.5 mass%, and it is especially preferable to exist in the range of 0.1-0.3 mass%. Further, the amount of the carboxyl end group is more preferably within a range of 3 to 10 equivalent / ton, and particularly preferably 3 to 5 equivalent / ton. In the present invention, the amount of oligomer and the amount of carboxyl end groups in the polyester resin are defined in this way when the oligomer content and the amount of carboxyl end groups are more than the above ranges, the polyester is used in a high temperature and high humidity atmosphere. This is because the hydrolysis reaction of the base resin proceeds and the durability of the back surface protective sheet for solar cell module of the present invention is impaired.

  In the present invention, the oligomer means a low polymer in which the number of repeating units (degree of polymerization) constituting the polyester resin is about 2 to 20. The oligomer content in the polyester resin is, for example, phenol / 1,2-dichlorobenzene (mass ratio = 50/50), phenol / 1,1,2,2-tetrachloroethane (mass ratio = 50/50, Alternatively, 100 mg of a polyester resin dissolved in 2 ml of any solvent such as 60/40), O-chlorophenol, and dichloroacetic acid is measured by liquid chromatography (HLC803D manufactured by Tosoh Corporation), and the polyester resin It can show by the ratio (mass%) of the oligomer with respect to.

  In addition, the amount of the carboxyl end group in the present invention is determined based on a certain amount of the polyester resin used in the present invention, orthocresol / chloroform (mass ratio = 50/50 or 60/40), phenol / 1,2-dichlorobenzene. (Mass ratio = 50/50), dissolved in phenol / 1,1,2,2-tetrachloroethane (mass ratio = 50/50 or 60/40), O-chlorophenol, and dichloroacetic acid It can be obtained by potentiometric titration with alkali.

  The polyester resin used in the present invention preferably has an intrinsic viscosity of 0.8 dl / g or more, more preferably 1.0 dl / g or more, particularly in the range of 1.2 to 1.5 dl / g. More preferably, it is within. This is because the film for solar cell back surface protective sheet of the present invention can be made excellent in toughness, rigidity, and heat resistance by defining the intrinsic viscosity of the polyester resin used in the present invention within the above range.

In addition, the said intrinsic viscosity in this invention is the density | concentration of 0.1 g / ml of the polyester-type resin used for this invention, phenol / 1, 2- dichlorobenzene (mass ratio = 50/50), phenol / 1,1. , 2,2-Tetrachloroethane (mass ratio = 50/50 or 60/40), O-chlorophenol, and the viscosity at 25 ° C. of a solution dissolved in any solvent of dichloroacetic acid. .
Here, in general, measuring the viscosity in a dilute solution of fine particles or a high-molecular substance can be very useful in knowing their physical properties while being a simple method. The ratio η _r = η / η ₀ between the viscosity η of the solution in which the target substance is dissolved and the viscosity η ₀ of the solvent is called relative viscosity. The viscosity η _{SP obtained} by subtracting 1 from this relative viscosity η _r , that is, η _SP = η _r1 = (η−η ₀ ) / η _0, is called specific viscosity, and the increase in viscosity due to the dissolution of the target substance in the solvent. It corresponds to. The specific viscosity η _SP is a function of the concentration of the target substance, and the extrapolated value of the specific viscosity to 0 is the intrinsic viscosity (extreme viscosity). Such intrinsic viscosity is a physical quantity that can be related to the particle size and molecular weight of the solute dispersed in the solution, and contains a lot of useful information. As the viscosity of the above solution, the value measured in accordance with JIS K7367-5 Plastic “Determination of viscosity of polymer diluted solution using capillary viscometer” Part 5: Thermoplastic polyester (TP) homopolymer and copolymer is used. Shall.

  In addition, the number average molecular weight of the polyester-based resin used in the present invention is for the above-mentioned solar cell back surface protection sheet, considering the use of the back surface protection sheet for solar cell modules using the film for solar cell back surface protection sheet of the present invention. The film is preferably within a range where desired hydrolysis resistance can be imparted to the film. In the present invention, the number average molecular weight is preferably in the range of 18000 to 45000, more preferably in the range of 18500 to 40000, and particularly preferably in the range of 19000 to 35000. In the present invention, the number average molecular weight is defined in the above range because there is a correlation with the amount of carboxyl end groups in the polyester resin, and when the number average molecular weight increases, the amount of carboxyl end groups is This is because the hydrolysis resistance is improved due to the decrease, and on the other hand, when the number average molecular weight is decreased, the amount of the carboxyl end group is increased, and thus the hydrolysis resistance is decreased.

In addition, the value measured on condition of the following by GPC (gel permeation chromatography) method shall be used for the said number average molecular weight in this invention.
(a) Apparatus: Gel permeation chromatograph GCP-244 (manufactured by WATERS)
(b) Column: Two Shodex HFIP 80M (made by Showa Denko KK)
(c) Solvent: Hexafluoropropanol (0.005N-sodium trifluoroacetate)
(d) Flow rate: 0.5 ml / min
(e) Temperature: 23 ° C
(f) Sample Concentration: 0.06% Solubility: Complete dissolution Filtration: Myshori disk W-13-5
(g) Injection amount: 0.300 ml
(h) Detector: R-401 type differential refractometer (WATERS)
(i) Fair molecular weight: PET-DMT (standard product)

  The polyester resin used in the present invention may be a resin in which the oligomer content and the carboxyl end group amount are within the above ranges, and may have a structure formed by condensation of a dicarboxylic acid compound and a diol compound. If it does not specifically limit.

  It does not specifically limit as a dicarboxylic acid compound which comprises the polyester-type resin used for this invention, For example, aromatic dicarboxylic acid, alicyclic dicarboxylic acid, or aliphatic dicarboxylic acid can be used.

  As the aromatic dicarboxylic acid, examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4′-diphenylether dicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid and the like can be mentioned. Among these, in the present invention, terephthalic acid, phthalic acid, and 2,6-naphthalenedicarboxylic acid can be preferably used.

  Examples of the alicyclic dicarboxylic acid include cyclohexane dicarboxylic acid.

  Examples of the aliphatic dicarboxylic acid component include adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like.

  In the present invention, only one kind of the above dicarboxylic acid compound may be used, or two or more kinds thereof may be used in combination. Furthermore, oxyacids such as hydroxyethoxybenzoic acid may be partially copolymerized.

The diol compound constituting the polyester resin used in the present invention is not particularly limited as long as it can be condensed with the dicarboxylic acid to constitute the polyester resin. Examples of the diol compound used in the present invention include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5. -Pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2'- Bis (4′-β-hydroxyethoxyphenyl) propane and the like can be mentioned.
Among these, in the present invention, it is preferable to use ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol, and most preferably ethylene glycol.

  In the present invention, only one type of diol component may be used, or two or more types may be used in combination.

  The polyester resin formed by condensation of the dicarboxylic acid compound and the diol compound is not particularly limited, and is a polyester resin formed by any combination of the dicarboxylic acid compound and the diol compound. Resin can be used. Among these, in the present invention, it is preferable to use polyethylene terephthalate, polyethylene naphthalate, polyethylene-2,6-naphthalenedicarboxylate, and particularly preferably polyethylene terephthalate.

  The polyester resin is constituted by condensation of the dicarboxylic acid compound and the diol compound. The polyester resin includes trimellitic acid, pyromellitic acid, glycerol, pentaerythritol, 2, Other compounds such as monofunctional compounds such as 4-dioxybenzoic acid, lauryl alcohol, and phenyl isocyanate may be copolymerized within a range in which the polymer is substantially linear.

  As a method for producing a polyester-based resin used in the present invention, for example, an acid component and a diol component are directly esterified, or a dialkyl ester is used as an acid component to cause a transesterification reaction with a diol component. After the step reaction, the reaction product is heated under reduced pressure to melt polymerize while removing excess diol component, and the second step reaction product, and further the second step reaction product And the like, and the like. In the present invention, it is preferable to use solid phase polymerization in order to obtain a polyester resin having a low oligomer content and a low carboxyl end group content.

  The solid phase polymerization method is not particularly limited, and a conventionally known method can be used. For example, a method of preliminarily crystallizing at a temperature of 180 ° C. or lower in advance and then heating at a temperature in the range of 180 ° C. to melting point (about 250 ° C.) for 5 to 50 hours in a nitrogen flow or in a vacuum of 1 torr or lower. Can be used.

  The polyester resin used in the present invention may contain a polyether compound for the purpose of adjusting the intrinsic viscosity to a desired range, for example. The polyether compound used in the present invention is not particularly limited, and for example, a polyether compound mainly composed of polyethylene oxide or diol can be used.

  Examples of the diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6 -Hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2'-bis (4'-β- Hydroxyethoxyphenyl) propane and the like can be mentioned.

  Examples of the polyether compound preferably used in the present invention include a polyether compound containing at least one of polyethylene oxide, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and a copolymer of these polyether compounds. Can be mentioned.

  In addition, as the polyether compound, an end-capped polyether compound may be used. This is because the end-capped polyether compound has an advantage that hydrolysis of the polyester resin can be suppressed. Examples of the end-capped polyether compound include a polyether compound in which the hydroxyl group at the end of the polyether is alkyl etherified, that is, end-capped with a methoxy group, an ethoxy group, or the like.

  Although it does not specifically limit as an average molecular weight of the said polyether compound, It is preferable that it is 500-10000, More preferably, it is 700-5000. This is because an average molecular weight of less than 500 is disadvantageous in that it is contained in the polyester resin. On the other hand, if the average molecular weight exceeds 10,000, the compatibility with the polyester resin may be deteriorated.

  Although it does not specifically limit as content of the polyether compound used for this invention, Usually, it is preferable to exist in the range of 0.1-10 mass% in a polyester-type resin, and 0.2-7 mass is especially preferable. % Is preferable, and the range of 0.2 to 5% by mass is particularly preferable. In the present invention, the content of the polyether compound is defined in this way, if the content is less than the above range, it is insufficient for adjusting the viscosity of the polyester resin, and the content is within the above range. It is because there exists a problem that physical properties, such as toughness of the said polyester-type resin, rigidity, and heat resistance, will change a lot when there is more.

(3) Film for solar cell back surface protection sheet The film for solar cell back surface protection sheet of this invention may contain the additive as needed. Additives used in the present invention include flame retardants, heat stabilizers, antioxidants, antistatic agents, organic lubricants such as pigments, dyes, fatty acid esters and waxes, or antifoaming agents such as polysiloxanes. Can do. Also, clay, mica, titanium oxide, calcium carbonate, carion, talc, wet or dry silica, colloidal silica, calcium phosphate, barium sulfate, alumina, zirconia, etc. to give easy slipping, wear resistance, scratch resistance Inorganic particles, acrylic acids, organic particles containing styrene, etc. as constituent components, so-called internal particles that are precipitated by a catalyst added during the polyester polymerization reaction, or a surfactant may be added. May be.

The apparent density of the film for solar cell back surface protection sheet of the present invention depends on the use of the back surface protection sheet for solar cell module using the film for solar cell back surface protection sheet of the present invention, etc. If it is in the range which can provide desired mechanical strength to, it will not specifically limit. It particular, in the present invention, the apparent density is preferably in a range of 0.85~1.37g / cm ^3, inter alia, in the range of 0.9~1.35g / cm ³ Is preferable, and it is particularly preferable to be within the range of 0.9 to 1.3 g / cm ³ . In the present invention, the apparent density is defined in this way because the apparent density is higher than the above range, so that the workability is lowered. This is because the durability cannot be obtained.
In addition, the said apparent density in this invention can be calculated | required by measuring the mass of the film for solar cell back surface protection sheets of volume known.

  The thickness of the solar cell back surface protective sheet film of the present invention is not particularly limited, and desired back support sheet for the solar cell module using the solar cell back surface protective sheet film of the present invention has a desired self-supporting property. It can be arbitrarily determined within the range that can be given. In particular, in the present invention, the range of 3 to 500 μm is preferable, the range of 25 to 250 μm is particularly preferable, and the range of 25 to 188 μm is particularly preferable. In the present invention, the thickness of the film for solar cell back surface protection sheet is defined because if the thickness of the film for solar cell back surface protection sheet is smaller than the above range, the desired self-supporting property cannot be obtained and is larger than the above range. This is because the cost increases. In addition, the said thickness shall use the value measured based on the JIS C2151 electrical plastic film test method.

  The film for a solar cell back surface protective sheet of the present invention may have a single layer structure or a multilayer structure. The multi-layer structure is not particularly limited, but a configuration in which another polymer layer such as polyester, polyolefin, polyamide, polyvinylidene chloride, acrylic polymer, etc. is laminated on the film made of the polyester resin is exemplified. can do.

(4) Manufacturing method of film for solar cell back surface protection sheet The manufacturing method of the film for solar cell back surface protection sheet of this invention is demonstrated. As a method for producing a film for protecting a back surface of a solar cell of the present invention, benzoxazine is within a range of 0.3 to 2% by mass, the benzoxazine is uniformly dispersed, and is further manufactured uniformly with a desired thickness. There is no particular limitation as long as it is a method capable of forming a film.
Among them, in the present invention, a pellet-shaped masterbatch is prepared using the benzoxazine, the additive, and the master base, and the masterbatch and the polyester-based resin are sufficiently mixed. It is preferable to mold after making the resin composition. It is because the film for solar cell back surface protection sheets excellent in the dispersibility of benzoxazine can be obtained. Although it does not specifically limit as a master base used when producing the said masterbatch, It is preferable that it is the same polyester-type resin as the polyester-type resin which comprises the said film for solar cell back surface protection sheets. . This is because the cost can be reduced by using the same polyester resin.

As a method for forming the above-mentioned polyester-based resin composition to produce a film for solar cell back surface protection sheet, an extrusion method after heating and melting, a T-die extrusion method, a cast molding method, an inflation method, other film molding methods, etc. Can be used.
The film for solar cell back surface protective sheet thus formed may be stretched uniaxially or biaxially by a tenter method, a tuber method, or the like, if necessary.

B. Back surface protection sheet for solar cell module Next, the back surface protection sheet for solar cell module of the present invention will be described. The back surface protection sheet for solar cell modules of the present invention has the above-described film for solar cell back surface protection sheet of the present invention and the resin film laminated on the film for solar cell back surface protection sheet. It is a feature.

  Next, the back surface protection sheet for solar cell modules of this invention is demonstrated, referring a figure. FIG. 1 is a schematic cross-sectional view showing an example of a back surface protection sheet for a solar cell module of the present invention. As illustrated in FIG. 1, the back surface protection sheet 10 for a solar cell module of the present invention has a configuration in which a resin film 2 is laminated on a film 1 for a back surface protection sheet for a solar cell.

  Moreover, the solar cell back surface protection sheet of this invention may have other structures other than the said film for solar cell back surface protection sheets, and the said resin film. FIG. 2 is a schematic cross-sectional view showing an example of a configuration having a gas barrier film as a configuration other than the solar cell back surface protective sheet film and the resin film. As illustrated in FIG. 2, the solar cell module back surface protective sheet 11 of the present invention may have a gas barrier film 5 between the solar cell back surface protective sheet film 1 and the resin film 2. The gas barrier film 5 used in the present invention is usually composed of a base film 3 and a gas barrier layer 4 formed on the base film.

  According to the back surface protection sheet for solar cell modules of the present invention, the film for solar cell back surface protection sheet is the above-described film for solar cell back surface protection sheet of the present invention, so that it is excellent in weather resistance. A back surface protection sheet can be obtained.

  The back surface protection sheet for solar cell modules of this invention has a film for solar cell back surface protection sheets, and a resin film. Hereinafter, each structure of the back surface protection sheet for solar cell modules of this invention is demonstrated in detail.

1. Film for Solar Cell Back Surface Protection Sheet The film for solar cell back surface protection sheet used for the back surface protection sheet for solar cell module of the present invention is the same as the content described in the section of “A. Film for Solar Cell Back Surface Protection Sheet”. Therefore, the description here is omitted.

2. Resin film Next, the resin film which comprises the back surface protection sheet for solar cell modules of this invention is demonstrated. The said resin film used for this invention will not be specifically limited if it has weather resistance, such as desired heat resistance, light resistance, and water resistance.

  Examples of the resin film include polyethylene resins, polypropylene resins, cyclic polyolefin resins, fluorine resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers ( ABS resin), polyvinyl chloride resin, fluorine resin, poly (meth) acrylic resin, polycarbonate resin, polyethylene terephthalate, polyethylene naphthalate and other polyester resins, various nylons Polyamide resins such as polyimide resins, polyamide imide resins, polyaryl phthalate resins, silicone resins, polysulfone resins, polyphenylene sulfide resins, polyethersulfone resins, polyurethane resins, aceters Cellulose resin, cellulose Mention may be made of a film made of a resin. In particular, in the present invention, it is preferable to use a film made of a fluorine resin, a cyclic polyolefin resin, a polycarbonate resin, a poly (meth) acrylic resin, a polypropylene resin, or a polyester resin.

  Moreover, as such a resin film, a biaxially stretched resin film can also be used.

  Furthermore, the resin film may have a configuration in which a plurality of films are laminated. Examples of the configuration in which such a plurality of films are laminated include a configuration in which a gas barrier film having an inorganic vapor deposition film is laminated, and a configuration in which a tough film is laminated.

  Examples of the resin film used in the present invention include an unstretched film that has not been stretched and a stretched film that has been stretched in a uniaxial direction or biaxial direction. It is preferable to use a film. When a stretched film is used, when the solar cell module is manufactured by thermocompression bonding the back surface protection sheet for the solar cell module of the present invention, the transparent front substrate, the filler, and the solar cell element. This is because the film shrinks remarkably due to thermocompression bonding, but there is no such problem if it is an unstretched film.

  The resin film used in the present invention may contain additives as necessary. Examples of the additive used in the present invention include coloring additives, ultraviolet absorbers, stabilizers, and flame retardants.

  Examples of coloring additives used in the present invention include various achromatic systems such as whitening agents and blackening agents, and chromatic systems such as red, orange, yellow, green, blue, purple, and others. Colorants such as dyes and pigments can be used. In the present invention, one or more of such coloring additives can be used.

  The whitening agent is added for the purpose of reusing solar light by reflecting or diffusing sunlight in the solar cell module back surface protection sheet of the present invention and reusing it for power generation in the solar cell element. . Further, by using such a whitening agent, it is possible to impart designability, decorativeness, and the like to the solar cell module using the back surface protection sheet for the solar cell module. When the solar cell module is installed on a roof or the like, it is possible to reflect or diffuse the reflected sunlight. Examples of such whitening agents include basic lead carbonate, basic lead sulfate, basic lead silicate, zinc white, zinc sulfide, lithopone, antimony trioxide, anatase-type titanium oxide, and rutile-type titanium oxide. White pigments can be used.

  The addition amount in the case of using the above whitening agent is within a range in which desired light reflectivity or light diffusibility can be imparted to the back surface protection sheet for the solar cell module of the present invention according to the type of the whitening agent. Although it will not specifically limit if it exists, it is preferable in the range of 0.1-30 mass% normally in the said resin film, and it is especially preferable that it exists in the range of 0.5-10 mass%.

  In the present invention, a gray achromatic dye / pigment in which a whitening agent and a blackening agent described later are mixed can also be used.

For example, when the solar cell module using the back surface protection sheet for a solar cell module of the present invention is installed on a roof or the like, the above blackening agent imparts designability, decorativeness, and the like that match the surrounding environment. It is added for the purpose. As such a blackening agent, for example, one or more black pigments such as carbon black (channel or furnace), black iron oxide, and the like can be used. In addition, the black layer formed by the blackening agent may be any black layer having a black taste such as a brown or brown black layer, a gray black layer, or the like.
The amount added in the case of using such a blackening agent is particularly limited as long as it is within a range in which desired designability and the like can be imparted to the back surface protection sheet for the solar cell module, depending on the type of blackening agent. Although it is not, usually the inside of the range of 0.1-30 mass% is preferable in the said resin film, and the inside of the range of 0.5-10 mass% is especially preferable.

When the solar cell module using the back surface protection sheet for the solar cell module of the present invention is installed on a roof or the like, for example, the colorant such as the chromatic dyes and pigments, It is added for the purpose of imparting design properties, decorativeness, etc. that match the environment. Examples of such colorants include azo, anthraquinone, phthalocyanine, thioindigo, quinacridone, dioxazine, and other organic dyes and pigments; Colorants such as inorganic pigments such as Bengala and others, and the like can be used. In the present invention, among the chromatic colorants, it is particularly preferable to use a blue colorant. This is because the polycrystalline silicon solar cell elements that occupy the majority of the current solar cell modules are blue, and thus have excellent design adaptability.
The addition amount in the case of using such a colorant is not particularly limited as long as it is within a range in which desired designability and the like can be imparted to the back surface protection sheet for solar cell module, but usually in the resin film. The range of 0.1 to 30% by mass is preferable, and the range of 0.5 to 10% by mass is particularly preferable.

The ultraviolet absorber used in the present invention absorbs harmful ultraviolet rays in sunlight and converts them into innocuous heat energy within the molecule, and in the back surface protection sheet for the solar cell module of the present invention. It has a function to prevent the active species that start photodegradation from being excited. In the present invention, examples of such ultraviolet absorbers include benzophenone, benzotriazole, saltylate, acrylonitrile, metal complex, hindered amine, ultrafine titanium oxide (particle size, 0 0.01 to 0.06 μm) or one or more kinds of inorganic ultraviolet absorbers such as ultrafine zinc oxide (0.01 to 0.04 μm) can be used.
In addition, the amount of addition in the case of using an ultraviolet absorber in the present invention is not particularly limited as long as it is within a range in which a desired ultraviolet absorptivity can be imparted to the solar cell module back surface protection sheet. In the said resin film, the inside of the range of 0.1-10 mass% is preferable, and especially the inside of the range of 0.3-10 mass% is preferable.

The light stabilizer used in the present invention has a function of capturing the excited active species that are the source of light deterioration in the back surface protection sheet for the solar cell module of the present invention and preventing the light deterioration. Is. In the present invention, as such a light stabilizer, for example, one or more light stabilizers such as hindered amine compounds, hindered-topiperidine compounds, and the like can be used.
In addition, the amount of addition in the case of using a light stabilizer in the present invention is not particularly limited as long as it is within a range in which a desired light stability can be imparted to the back surface protection sheet for a solar cell module. In the said resin film, the inside of the range of 0.1-10 mass% is preferable, and the inside of the range of 0.3-10 mass% is especially preferable.

  The resin film in the present invention preferably contains a flame retardant. The flame retardant used in the present invention is roughly classified into an organic type and an inorganic type. Examples of the organic system include phosphorus-based, phosphorus + halogen-based, chlorine-based, and bromine-based flame retardants, and examples of the inorganic system include aluminum hydroxide, antimony-based, magnesium hydroxide, guanidine-based, zirconium-based, Flame retardants such as zinc borate can be used. In this invention, a flame retardance can be provided to the back surface protection sheet for solar cell modules of this invention by adding arbitrarily 1 type, or 2 or more types of the said flame retardant.

  The thickness of the resin film used in the present invention is not particularly limited, and may be appropriately determined according to the use of the back surface protection sheet for the solar cell module of the present invention. Usually, it is preferably in the range of 10 to 300 μm, particularly The range of 15 to 150 μm is preferable.

The resin film used in the present invention preferably has a heat shrinkage of 3.0% or less at 150 ° C. for 30 minutes, more preferably 1.0% or less, particularly 0.3 to 0.00. It is preferable to be within the range of 5%. When the thermal shrinkage rate of the resin film is within the upper range, it is possible to produce a backside protection sheet for solar cell modules that has a low influence on the shrinkage rate of the backside protection sheet for solar cell modules of the present invention and has an excellent appearance. This is because it becomes easy.
Here, the said thermal contraction rate can be measured based on the JIS C2151 electrical plastic film test method.

  Next, the manufacturing method of the resin film used for this invention is demonstrated. As a manufacturing method of the resin film used for this invention, the method similar to the manufacturing method of the film for solar cell back surface protection sheets described in the above-mentioned "A. Film for solar cell back surface protection sheet" can be used. Therefore, the description here is omitted.

3. Other Configurations The back surface protective sheet for solar cell module of the present invention may have other configurations other than the resin film and the film for solar cell back surface protective sheet. Examples of such other configurations include a gas barrier film. In the present invention, it is particularly preferable to use a gas barrier film from the viewpoint of improving the moisture resistance of the back surface protective sheet for solar cell module.

(1) Gas barrier film The gas barrier film used in the present invention will be described. The gas barrier film is not particularly limited as long as it has a function capable of imparting desired moisture resistance to the back surface protective sheet for a solar cell module of the present invention. Usually, at least one of the base film and the base film is used. What has the structure which consists of a gas barrier layer formed in the single side | surface is used.

  As an aspect in the case of using the above-mentioned gas barrier film for the back surface protective sheet for solar cell module of the present invention, a desired moisture resistance can be imparted to the back surface protective sheet for solar cell module of the present invention and stable for a long time. In particular, there is no particular limitation as long as the desired moisture resistance can be maintained. As such an embodiment, the film for solar cell back surface protection sheet is used as a base film, a gas barrier layer is laminated on the film for solar cell back surface protection sheet, and the resin film is a base material. Examples of use as a film include a mode in which a gas barrier layer is laminated on the resin film to form a gas barrier film, and a mode in which a gas barrier film is disposed between the solar cell back surface protective sheet film and the resin film. it can. Moreover, when using several gas barrier film, the aspect which combined said aspect may be sufficient. Especially, in this invention, the aspect which arrange | positions the said gas barrier film between the said film for solar cell back surface protection sheets and the said resin film is preferable. This is because the moisture-proof stability over time can be improved according to such a configuration.

  As an aspect which arrange | positions the said gas-barrier film between the said film for solar cell back surface protection sheets, and the said resin film, the aspect as shown in FIG. 2 already demonstrated typically can be illustrated. A back protective sheet 11 for a solar cell module illustrated in FIG. 2 includes one gas barrier film 5 including a base film 3 and a gas barrier layer 4 between a solar cell back protective sheet film 1 and a resin film 2. It is the aspect which has. In FIG. 2, the gas barrier film 5 is disposed so that the gas barrier layer 4 faces the solar cell back surface protective sheet film 1 side, but the reverse arrangement, that is, the gas barrier layer 4 faces the resin film 2 side. The gas barrier film 5 may be disposed on the surface.

  When using a gas barrier film for the back surface protection sheet for solar cell modules of this invention, the number of the gas barrier films to be used is not specifically limited, It is not restricted only to 1 sheet, You may use 2 or more sheets. The quantity used of such a gas barrier film takes into account the moisture resistance required for the back protection sheet for solar cell modules and the moisture resistance of the gas barrier film, depending on the use of the back protection sheet for solar cell modules, etc. What is necessary is just to determine suitably. Especially, it is preferable to use 1 or 2 gas barrier films from a viewpoint which simplifies the manufacturing process of the said back surface protection sheet for solar cell modules.

  The aspect in case the back surface protection sheet for solar cell modules of this invention has two gas barrier films is demonstrated, referring a figure. FIG. 3 is a schematic cross-sectional view showing an example of the case where the back surface protective sheet for a solar cell module of the present invention has two gas barrier films. As an aspect in the case of using two gas barrier films for the back surface protective sheet 12 for the solar cell module of the present invention, as shown in FIG. 3, between the solar cell back surface protective sheet film 1 and the resin film 2, A mode in which two gas barrier films 5 composed of the base film 3 and the gas barrier layer 4 are laminated can be exemplified.

  FIG. 4 is a schematic cross-sectional view showing another example when the back surface protective sheet for a solar cell module of the present invention has two gas barrier films. As shown in FIG. 4, as another aspect in which the back surface protective sheet 13 for solar cell modules of the present invention has two gas barrier films, between the solar cell back surface protective sheet film 1 and the resin film 2, The aspect which arrange | positions the two gas barrier films 5 laminated | stacked through the toughness film 6 can be illustrated.

  Hereinafter, each structure of such a gas barrier film will be described.

i. Base Film First, the base film used for the gas barrier film will be described. The material constituting the base film used in the present invention is a material that has durability that can withstand the process conditions when forming a gas barrier layer described later and that exhibits tight adhesion to the gas barrier layer. However, the material is not limited, and a suitable material can be appropriately selected and used according to various physical properties required for the back surface protective sheet for solar cell module of the present invention.

Specific examples of the material constituting the base film include, for example, polyethylene resins, polypropylene resins, cyclic polyolefin resins, syndiotactic polystyrene resins and other polystyrene resins, acrylonitrile-styrene copolymers (AS resins). , Acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine resin, poly (meth) acrylic resin, polycarbonate resin, polyethylene terephthalate or polyethylene naphthalate Polyester resins such as nylon, various polyamide resins such as nylon, polyimide resins, polyamideimide resins, polyaryl phthalate resins, silicone resins, polysulfone resins, polyphenylene sulfide resins, polyesters Tersulfone resin, Polyurethane resins, acetals - Le resins, cellulose - scan-based resins, and various resins other like.
In the present invention, among the above materials, it is preferable to use a cyclic polyolefin resin, a polycarbonate resin, a poly (meth) acrylic resin, a polystyrene resin, a polyamide resin, or a polyester resin. . This is because by using such a material, the solar cell module back surface protective sheet of the present invention has good durability and excellent workability.
Moreover, in this invention, 1 type thru | or 2 or more types of the said material can be used as a constituent material of the said base film.

  The thickness of the substrate film may be appropriately determined according to various physical properties required for the back surface protective sheet for solar cell module of the present invention, but is usually preferably in the range of 9 to 300 μm, particularly in the range of 12 to 200 μm. The inside is preferable.

  The base film may contain additives as necessary. Examples of the additive used in the present invention include a lubricant, a crosslinking agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a lubricant, a reinforcing fiber, a reinforcing agent, an antistatic agent, a flame retardant, and a flame retardant. Further, a foaming agent, an antifungal agent, a pigment and the like can be used, and a modifying resin and the like can also be used. In the present invention, among the above additives, it is particularly preferable to use an ultraviolet absorber, a light stabilizer, and an antioxidant.

  Examples of the ultraviolet absorber include benzophenone-based, benzotriazole-based, sulfate-based, acrylonitrile-based, metal complex-based, ultrafine titanium oxide (particle diameter, 0.01 to 0.06 μm), or ultrafine particle oxidation. One or more inorganic ultraviolet absorbers such as zinc (0.01 to 0.04 μm) can be used.

  In addition, as the light stabilizer, for example, one or more of hindered amine compounds, hindered-piperidine compounds, and the like can be used.

  Further, the antioxidant is to prevent oxidative deterioration of the base film due to light or heat, for example, phenol-based, amine-based, sulfur-based, phosphoric acid-based and other antioxidants. Can be used.

  Further, the ultraviolet absorber, light stabilizer, and antioxidant are composed of, for example, the above-mentioned ultraviolet absorber such as benzophenone or hindered amine compound in the main chain or side chain constituting the polymer. Polymer-type UV absorbers, light stabilizers, antioxidants, and the like obtained by chemically bonding a light stabilizer or a phenol-based antioxidant can also be used.

  The contents of the ultraviolet absorber, the light stabilizer, and the antioxidant may be appropriately determined according to various physical properties required for the base film, but usually 0.1 to 10 in the base film. Within the range of mass% is preferable.

A surface treatment layer may be formed on the base film in advance in order to improve the tight adhesion with a gas barrier layer described later. Examples of such a surface treatment layer include surface treatment such as corona discharge treatment, ozone treatment, plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals, and the like. Examples thereof include a corona treatment layer, an ozone treatment layer, a plasma treatment layer, and an oxidation treatment layer.
The surface treatment may be performed in a separate process. For example, when performing a surface treatment such as a plasma treatment or a glow discharge treatment, a pretreatment for forming a vapor-deposited film of an inorganic oxide, which will be described later, is performed. In such a case, there is an advantage that the manufacturing cost can be reduced.

  The surface treatment layer is formed as a method for improving the tight adhesion between the base film and a gas barrier layer described later. The method for improving the tight adhesion includes the surface treatment layer. In addition, for example, based on a coating agent layer such as a primer coat agent layer, an undercoat agent layer, an anchor coat agent layer, an adhesive layer, or a deposited anchor coat agent layer. A method of forming on the surface of the material film can also be used. Examples of the material constituting such a coating agent layer include polyester resins, polyamide resins, polyurethane resins, epoxy resins, phenol resins, (meth) acrylic resins, and polyvinyl acetate resins. A resin, a polyolefin resin such as polyethylene or polypropylene, or a copolymer or modified resin thereof, a cellulose resin, or the like can be used.

Moreover, in this invention, in the formation process at the time of forming the gas barrier layer mentioned later on at least one surface of said base film, it vapor-deposits on at least one surface of a base film in order to protect a base film. A protective film may be formed. Such a vapor deposition protective film is, for example, a chemical vapor deposition method (chemical vapor deposition method, CVD method) such as a chemical vapor deposition method, a thermal chemical vapor deposition method, a photochemical vapor deposition method, or a vacuum vapor deposition method (resistance). Formation of vapor-deposited thin films of inorganic oxides on base films using physical vapor deposition (PVD) methods such as heating, dielectric heating, EB heating), sputtering, ion plating, etc. It can be given by doing.
Although it does not specifically limit as an inorganic oxide which comprises a vapor deposition protective film, For example, a silicon oxide can be used.

  The thickness of the vapor deposition protective film is preferably less than 150 mm. More specifically, it is preferably within a range of 10 to 100%, particularly preferably within a range of 20 to 80%, and particularly preferably within a range of 30 to 60%. If the film thickness is thicker than the above range, it may be difficult to form a uniform vapor deposition protective film, and if it is thinner than the above range, the substrate film may be insufficiently protected. It is.

ii. Next, the gas barrier layer used for the gas barrier film will be described. The gas barrier layer is not particularly limited as long as it can provide the moisture barrier property to the gas barrier film. For example, a metal thin film, an inorganic oxide deposited film, an organic thin film, and the like, and A combination of these is used. In particular, in the present invention, an inorganic oxide vapor-deposited film is preferably used. This is because an inorganic oxide vapor-deposited film is excellent in denseness, and therefore has high moisture resistance per unit thickness, and also has good adhesion to the substrate film.

The inorganic oxide deposition film used in the present invention is not particularly limited as long as it is a thin film on which a metal oxide is deposited. Examples of the metal used for such a deposited film include silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), and boron. (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), and the like.
Especially in this invention, it is preferable to use the vapor deposition film of the metal oxide of silicon (Si) and aluminum (Al) as said vapor deposition film.

  Further, the content of oxygen atoms in the metal oxide is not particularly limited, and may be arbitrarily determined according to the metal species used in the metal oxide. A metal oxide can be expressed as MOx, where M is a metal element, O is an oxygen atom, and X is the number of oxygen atoms. In this invention, when the said metal oxide is described in this way, it is preferable that the value of X is 0-2. When silicon (Si) and aluminum (Al) are used as the metal constituting the metal oxide, the value of X is preferably in the range of 1.0 to 2.0 in the case of silicon (Si). In the case of aluminum (Al), the range of 0.5 to 1.5 is preferable.

  The metal used for the said inorganic oxide vapor deposition film can also be used by 1 type, or 2 or more types of mixtures, and can comprise the vapor deposition film of the inorganic oxide mixed by the dissimilar material.

The thickness of the inorganic oxide vapor-deposited film varies depending on the type of metal or metal oxide used, but is usually preferably in the range of 50 to 4000 mm, particularly in the range of 100 to 1000 mm. preferable.
In addition, when the said vapor deposition film | membrane of an inorganic oxide has a multilayer structure, the said thickness shall cover the total thickness.

  The gas barrier layer used in the present invention may have a single layer structure or a multilayer structure. In the case of a multi-layer structure, a structure in which layers having the same composition are stacked may be used, or a structure in which layers having different compositions may be stacked.

iii. Gas barrier film As the gas barrier property of the gas barrier layer used in the present invention, depending on the use mode of the gas barrier film, it is particularly within the range capable of imparting desired moisture resistance to the back surface protective sheet for solar cell module of the present invention. It is not limited. Among these gas barrier films used in the present invention, the oxygen gas permeability ^1cc / m 2 / day / atm or less, and preferably less inter alia ^{0.5cc / m 2 / day / atm} . The water vapor transmission rate is preferably 1 g / m ² / day or less, particularly preferably 0.5 g / m ² / day or less.
The oxygen gas permeability is a value measured using an oxygen gas permeability measuring apparatus (manufactured by MOCON, OX-TRAN 2/20: trade name) under the conditions of a measurement temperature of 23 ° C. and a humidity of 90% Rh. It is. The water vapor transmission rate is a value measured using a water vapor transmission rate measuring device (manufactured by MOCON, PERMATRAN-W 3/31: trade name) under the conditions of a measurement temperature of 37.8 ° C. and a humidity of 100% Rh. It is.

  The configuration of the gas barrier film used in the present invention is not particularly limited as long as it is a configuration capable of exhibiting the gas barrier property, and the gas barrier layer is formed on at least one surface of the base film. I just need it. Therefore, the gas barrier layer may be formed only on one side of the base film, or the gas barrier layer may be formed on both sides of the base film.

iv. Production method of gas barrier film The production method of the gas barrier film used in the present invention is particularly limited as long as it is a method capable of forming a homogeneous gas barrier layer on the base film according to the material constituting the gas barrier layer. Not.

  When forming a vapor deposition film of an inorganic oxide as a gas barrier layer on the base film, the formation method is not particularly limited as long as it can form a uniform vapor deposition film with a desired film thickness. As a method for forming the vapor deposition film in the present invention, a physical vapor deposition method and a chemical vapor deposition method, or a method using both of them can be used.

  Examples of the physical vapor deposition method include physical vapor deposition methods (Physical Vapor) such as vacuum deposition method (resistance heating, dielectric heating, EB heating method), sputtering method, ion plating method, ion cluster beam method, and the like. Deposition method, PVD method). More specifically, a metal oxide is used as a raw material, and this is heated and vapor-deposited on a base film, or a metal or metal oxide is used as a raw material and oxygen is introduced. An oxidation reaction vapor deposition method of oxidizing and vapor-depositing on a base film, and a plasma-assisted oxidation reaction vapor deposition method of assisting an oxidation reaction with plasma can be used. Moreover, as a heating method for the vapor deposition material, for example, a resistance heating method, a high frequency induction heating method, an electron beam heating method (EB), or the like can be used.

  Examples of the chemical vapor deposition include chemical vapor deposition (chemical vapor deposition, CVD) such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. Can do. More specifically, on one side of the base film, a monomer gas for vapor deposition such as an organosilicon compound is used as a raw material, an inert gas such as argon gas or helium gas is used as a carrier gas, A vapor deposition film of an inorganic oxide such as silicon oxide can be formed by using a low temperature plasma chemical vapor deposition method using an oxygen gas or the like as an oxygen supply gas and using a low temperature plasma generator or the like. As the low-temperature plasma generator, for example, generators such as high-frequency plasma, pulse wave plasma, and microwave plasma can be used. In the present invention, in order to obtain highly active and stable plasma, a high-frequency plasma method is used. It is preferred to use a generator.

  The inorganic oxide vapor-deposited film used in the present invention is a composite film in which two or more vapor-deposited films of different inorganic oxides are combined using both the physical vapor deposition method and the chemical vapor deposition method. There may be. As such a composite film, an inorganic oxide vapor-deposited film is provided by chemical vapor deposition, which is dense and flexible, and can relatively prevent the occurrence of cracks. It is preferable to form an inorganic oxide vapor deposition film composed of a composite film composed of two or more layers by providing an inorganic oxide vapor deposition film by physical vapor deposition on the film.

(2) Others The back protective sheet for a solar cell module of the present invention may have a configuration other than the gas barrier film. Examples of such other configurations include a primer layer for attaching a terminal box.

4). The back surface protection sheet for solar cell modules The back surface protection sheet for solar cell modules of this invention was laminated | stacked on the film for solar cell back surface protection sheets of this invention mentioned above, and the said film for solar cell back surface protection sheets. If it has a resin film, it will not specifically limit. In the present invention, the back protective sheet for a solar cell module has a through hole for passing a terminal for taking out the current generated by the solar cell element to the outside after the solar cell module is manufactured. Is preferred. The form of such a through-hole is not particularly limited, and specific aspects such as position, size, shape and number are the wiring form of the solar cell module using the solar cell module back surface protective sheet and the like. It may be arbitrarily determined according to the above.

5. Next, the manufacturing method of the back surface protection sheet for solar cell modules of this invention is demonstrated. As a manufacturing method of the back surface protection sheet for solar cell modules of this invention, if the each structure of the said back surface protection sheet for solar cell modules mentioned above can be laminated | stacked with sufficient adhesiveness, it will not specifically limit. As such a method, for example, a method of dry laminating the resin film on the above-described film for protecting a back surface of a solar cell of the present invention through an adhesive layer can be exemplified. Moreover, when using the said gas barrier film, the method for carrying out the dry lamination of the film for solar cell back surface protection sheets, and the resin film can respectively be illustrated through the adhesive layer on both surfaces of the said gas barrier film. .

  Examples of the laminating adhesive constituting the adhesive layer include, for example, polyvinyl acetate adhesives, homopolymers such as ethyl acrylate, butyl, 2-ethylhexyl ester, and these, methyl methacrylate, acrylonitrile , Polyacrylic acid ester adhesives, cyanoacrylate adhesives, copolymers of styrene, etc., copolymers of ethylene and monomers such as vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid, etc. Ethylene copolymer adhesives, polyolefin adhesives made of polyethylene resin or polypropylene resin, cellulose adhesives, polyester adhesives, polyamide adhesives, polyimide adhesives, urea resins or melamines Amino resin adhesives made of resin, phenol resin adhesives Epoxy adhesives, polyurethane adhesives, reactive (meth) acrylic adhesives, chloroprene rubber, nitrile rubber, styrene-butadiene rubber, styrene-isoprene rubber, rubber adhesives, silicone adhesives, An adhesive such as an inorganic adhesive made of alkali metal silicate, low melting point glass, or the like can be used. Further, the composition system of these adhesives may be any composition form such as an aqueous type, a solution type, an emulsion type, and a dispersion type, and the form is a film / sheet type, powder type, solid type, etc. Further, the bonding mechanism may be any form such as a chemical reaction type, a solvent volatilization type, a heat melting type, and a hot pressure type.

  In the present invention, it is preferable to use a rubber adhesive made of styrene-butadiene rubber, styrene-isoprene rubber or the like as the adhesive. This is because the material is excellent in hydrolysis resistance and is most suitable for the high cold resistance required in this application.

  Moreover, in the said adhesive bond layer, it is preferable to bridge | crosslink the said adhesive agent by including a hardening | curing agent or a crosslinking agent. This is because by forming a crosslinked structure, an adhesive excellent in high heat resistance, moist heat resistance and the like can be obtained.

  As such a curing agent or crosslinking agent, an aliphatic or alicyclic isocyanate, or an isocyanate compound such as an aromatic isocyanate can be used. -Hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthylene diisocyanate (NDI) ), Tolidine diisocyanate (TODI), xylylene diisocyanate (XDI), and the like.

The adhesive is, for example, for a gas barrier film or a solar cell back surface protective sheet by a coating method such as a roll coating method, a gravure roll coating method, a kiss coating method, or the like, or a printing method. It can be coated on a film and a resin film. The coating amount is preferably in the range of 0.1 to 10 g / m ² (dry state).

  In addition, in order to prevent ultraviolet-ray deterioration etc., the above-mentioned ultraviolet absorber or light stabilizer can be added to the adhesive. As the ultraviolet absorber or light stabilizer, one or more of the aforementioned ultraviolet absorbers, or one or more of the light stabilizers can be used in the same manner. The amount used varies depending on the particle shape, density, etc., but is preferably in the range of 0.1 to 10% by mass in the adhesive.

  In the present invention, when two or more of the gas barrier films are laminated, the gas barrier layers may be laminated so that the base films are opposed to each other, or one gas barrier layer and the other base film are laminated. You may laminate | stack so that may oppose. The lamination method is not particularly limited, and for example, the dry lamination method can be used.

In the present invention, when two gas barrier films are laminated via a tough resin film, the base film and the tough film constituting the gas barrier film may face each other, The gas barrier layer and the tough film constituting the gas barrier film may be opposed to each other. Furthermore, the two gas barrier films may have the same surface facing the tough film or may be different from each other.
Here, the method for laminating the two gas barrier films via the tough resin film is not particularly limited, and for example, the dry laminating method can be used.

  In the present invention, examples of the tough resin film include polyester resins, polyamide resins, polyaramid resins, polypropylene resins, polycarbonate resins, polyacetal resins, polystyrene resins, and fluorine resins. A resin or other strong resin film or sheet can be used.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described more specifically by using examples.

  Unless otherwise specified, the measurement of the oligomer content, carboxyl end group content, and intrinsic viscosity, which are the basic characteristics of the PET resin for solar cell back surface protective sheet and the film for solar cell back surface protective sheet used in Examples and Comparative Examples, are as follows. The following method was used.

<Measurement of oligomer content>
For each of the PET resin for solar cell back surface protective sheet film and the film for solar cell back surface protective sheet, 100 mg of polymer was extracted and dissolved in 2 ml of orthochlorophenol by liquid chromatography (HLC803D manufactured by Tosoh Corporation). Measured and expressed as a ratio (% by mass) of oligomer to polymer.

<Measurement of carboxyl end group amount>
It calculated | required by melt | dissolving the polymer 0.5g extracted about each of PET resin for films for solar cell back surface protection sheets, and the film for solar cell back surface protection sheets in ortho cresol, and potentiometric titration with potassium hydroxide.

<Measurement of intrinsic viscosity>
The viscosity at 25 ° C. of a solution obtained by dissolving the polymer extracted from each of the PET resin for a solar cell back surface protective sheet film and the solar cell back surface protective sheet film in orthochlorophenol at a concentration of 0.1 g / ml was determined.

[Example 1]
1. Production of film for protecting back surface of solar cell 100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, 0.08 part by weight of calcium acetate monohydrate, and 0.03 part by weight of antimony trioxide in this order In the reactor, the temperature was raised by a conventional method to conduct a transesterification reaction. Next, 0.16 parts by weight of lithium acetate and 0.24 parts by weight of trimethyl phosphate were added to the transesterified product, and then the pressure inside the system was gradually reduced to a temperature of 285 ° C. and a pressure of 1 mmHg. Polymerization was conducted by a conventional method to obtain polyethylene terephthalate (PET) having an intrinsic viscosity of 0.52 dl / g. The PET is chipped and subjected to solid phase polymerization at 225 ° C. under a reduced pressure of 0.5 mmHg using a rotary vacuum polymerization apparatus, and a PET resin for solar cell back surface protection sheet having an intrinsic viscosity of 1.07 dl / g is obtained. Obtained.
After the PET resin was dried and dehydrated and pulverized, 11 parts by weight of benzoxazine per 100 parts by weight of the PET resin was mixed and pelletized to obtain a master batch. A dried and dehydrated mixture consisting of 94 parts by weight of PET and 6 parts by weight of the masterbatch is fed to a known 65 mm extruder, melted at 275 ° C., and then extruded from a T-die to form a film having a thickness of 470 μm. Obtained. Next, the film was simultaneously biaxially stretched at 95 ° C. by 2.5 times in the longitudinal direction and 2.5 times in the width direction using a tenter. Subsequently, heat setting was performed at 235 ° C. to produce a biaxially oriented film for solar cell back surface protection sheet having a thickness of 75 μm.

2. Production of Adhesive A styrene-butadiene rubber-based adhesive into which a crosslinked network containing an aromatic isocyanate curing agent was introduced was mixed with 2.0% by mass of a benzophenone-based ultraviolet absorber as an ultraviolet absorber to produce an adhesive.

3. Production of Resin Film To polypropylene resin, titanium oxide (5% by mass) as a whitening agent, benzophenone-based ultraviolet absorber (1% by mass) as an ultraviolet absorber, and a hindered amine-based light stabilizer (as a light stabilizer) 1% by mass), other necessary additives are added, and kneaded sufficiently to prepare a polypropylene resin composition, and then the polypropylene resin composition is molded to a resin film having a thickness of 120 μm. Manufactured.

4). Production of gas barrier film A polyethylene terephthalate film having a thickness of 12 μm having a corona-treated surface on one side was used as a base film, and this film was attached to a delivery roll of a high-frequency dielectric heating type vacuum deposition apparatus. A vapor-deposited film of silicon oxide having a thickness of 800 mm (80 nm) was formed on the corona-treated surface of the terephthalate film under the following conditions to produce a gas barrier film.

(Deposition conditions)
Degree of vacuum in the deposition chamber: 1.33 × 10 ⁻² Pa (1 × 10 ⁻⁴ Torr)
Vacuum degree in winding chamber; 1.33 × 10 ⁻² Pa
Electron beam power: 25 kW
Film transport speed: 100m / min. Deposition surface; Corona treatment surface

5. Preparation of back surface protection sheet for solar cell module One of the 75 μm thick solar cell back surface protection sheet films manufactured by the above method was subjected to corona surface treatment, and the adhesive prepared by the above method was applied to the corona treatment surface by gravure - Turkey - by method, a co to a film thickness of 5.0 g / m 2 ^(dry) - and computing, dried laminating - to form a preparative adhesive layer.
Next, the surface of the laminating adhesive layer formed above is overlaid so that the surface of the vapor deposited silicon oxide film of the gas barrier film formed by the above method and having a thickness of 800 mm of silicon oxide is opposed to each other. After that, both were laminated by dry lamination.
Next, the above-mentioned adhesive was applied to the non-deposited film surface of the gas barrier film formed with the above-described dry laminated laminated silicon oxide film having a thickness of 800 mm by a gravure roll coating method to a film thickness of 5.0 g / Coating was performed so as to be m ² (dry state), and after drying, an adhesive layer for laminating was formed.
Next, the resin film prepared above is overlaid on the surface of the adhesive layer for laminating formed as described above, and then both of them are dry laminated to form a back surface protection sheet for a solar cell module. Made.

[Example 2]
Example of production of film for solar cell back surface protection sheet, except that a film for solar cell back surface protection sheet was prepared using the dry and dehydrated mixture consisting of 90 parts by weight of the PET resin and 10 parts by weight of the master batch. 1 was used to prepare a back surface protection sheet for a solar cell module.

[Example 3]
In the production of a film for solar cell back surface protection sheet, the film for solar cell back surface protection sheet was prepared by using a dried and dehydrated mixture consisting of 88 parts by weight of the PET resin and 12 parts by weight of the master batch. 1 was used to prepare a back surface protection sheet for a solar cell module.

[Example 4]
In the production of a film for protecting a back surface of a solar cell, a film for protecting a back surface of a solar cell was prepared by using a dried and dehydrated mixture comprising 97 parts by weight of the PET resin and 3 parts by weight of the master batch. 1 was used to prepare a back surface protection sheet for a solar cell module.

[Example 5]
In the production of a film for solar cell back surface protection sheet, the film for solar cell back surface protection sheet was prepared by using a dried and dehydrated mixture consisting of 82 parts by weight of the PET resin and 18 parts by weight of the master batch. 1 was used to prepare a back surface protection sheet for a solar cell module.

[Example 6]
A solar cell module back surface protective sheet was prepared in the same manner as in Example 1 except that the PET resin had an intrinsic viscosity of 0.87 dl / g in the production of the solar cell back surface protective sheet film. did.

[Example 7]
A solar cell module back surface protective sheet was prepared in the same manner as in Example 1 except that the PET resin had an intrinsic viscosity of 1.27 dl / g in the production of the solar cell back surface protective sheet film. did.

[Example 8]
A solar cell module back surface protection sheet was prepared by the method of Example 1 except that the PET resin had an intrinsic viscosity of 1.43 dl / g in the production of a solar cell back surface protection sheet film.

[Comparative Example 1]
A solar cell module back surface protection sheet was prepared in the same manner as in Example 1 except that benzoxazine was not added in the production of the solar cell back surface protection sheet.

[Comparative Example 2]
In the production of a film for protecting the back surface of a solar cell, a film for protecting the back surface of a solar cell was prepared by using a dried and dehydrated mixture comprising 98 parts by weight of the PET resin and 2 parts by weight of the masterbatch. 1 was used to prepare a back surface protection sheet for a solar cell module.

[Comparative Example 3]
A back protection sheet for a solar cell module was prepared in the same manner as in Comparative Example 2, except that the PET resin had an intrinsic viscosity of 0.73 dl / g. did.

[Comparative Example 4]
In the production of the solar cell back surface protective sheet film, a PET resin having an intrinsic viscosity of 2.33 dl / g was obtained by the same method as in Example 1. When an attempt was made to extrude the PET resin from a T die in the same manner as in Comparative Example 2, a film for a solar cell back surface protective sheet having poor fluidity and a uniform thickness could not be obtained. Therefore, about the comparative example 4, the basic characteristic measurement of the film for solar cell back surface protection sheets, and preparation and evaluation of the back surface protection sheet for solar cell modules were not implemented.

[Basic characteristic measurement]
Table 1 shows the results of measurement of basic characteristics of the PET resin for solar cell back surface protective sheet film and the solar cell back surface protective sheet film in the above Examples and Comparative Examples.

[Evaluation]
About the back surface protection sheet for solar cell modules in the said Example and comparative example, it measured about (1) exposure test and (2) breaking strength. The results are shown in Table 2.

(1) Exposure test About the back surface protection sheet for solar cell modules, 280-400 nm, 100 mw / cm2 light was irradiated from the film side for solar cell back surface protection sheets for 168 hours, and the solar cell module before and after irradiation. About the back surface protection sheet | seat, the color was measured using color computer SM-C by Suga Test Instruments.

(2) Breaking strength Under the conditions of a temperature of 85 ° C. and a humidity of 85%, a solar cell module back surface protection sheet before and after storage for 2000 hours was cut into a width of 15 mm and a length between chucks of 10 mm, based on JIS K7127. The breaking strength was measured. The unit is represented by N / 15 mm.

About the back surface protection sheet for solar cell modules, 100 mw / cm <2> (280-400 nm) and the comparative measurement of the color before and after exposing for 168 hours were implemented. As a result, there was no change in color for the examples. Further, the back surface protection sheet for the solar cell module of the comparative example has a great change in color.
Moreover, about the back surface protection sheet | seat for solar cell modules, the comparative measurement of the fracture strength after 2000 degreeC and 85 degreeC and 85% of relative humidity was implemented. As a result, the strength maintenance rate of the example was 70% or more, which was better than that of the comparative example.

It is the schematic which shows an example of the back surface protection sheet for solar cell modules of this invention. It is the schematic which shows the other example of the back surface protection sheet for solar cell modules of this invention. It is the schematic which shows the other example of the back surface protection sheet for solar cell modules of this invention. It is the schematic which shows the other example of the back surface protection sheet for solar cell modules of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Film for solar cell back surface protection sheets 2 ... Resin film 3 ... Base film 4 ... Gas barrier layer 5 ... Gas barrier film 6 ... Tough film 10, 11, 12, 13 ... Back surface protection sheet for solar cell modules

Claims (4)

A film for protecting a back surface of a solar cell comprising a polyester resin containing a benzoxazine represented by the following chemical formula, wherein the content of the benzoxazine is 0.3 to 2% by mass, and the polyester resin is an oligomer The film for solar cell back surface protection sheets characterized by the content of 0.1-0.6 mass%, and also the amount of carboxyl terminal groups being 3-15 equivalent / ton.

It has the film for solar cell back surface protection sheets of Claim 1, and the resin film laminated | stacked on the said film for solar cell back surface protection sheets, The back surface protection sheet for solar cell modules characterized by the above-mentioned. A gas barrier film comprising a base film and a gas barrier layer formed on at least one side of the base film is provided between the solar cell back surface protective sheet film and the resin film. Item 3. A back surface protective sheet for a solar cell module according to Item 2.   The back protective sheet for a solar cell module according to claim 3, wherein two or more gas barrier films are provided between the film for solar cell back protective sheet and the resin film.

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