JP2015192000A - Method of manufacturing sealing fil for solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a sealing film for solar cell capable of manufacturing a sealing film for solar cell, where sneaking is less likely to occur while manufacturing a solar cell, excellently without leaving an unmelted portion.SOLUTION: In a method of manufacturing a sealing film 13B for solar cell including a step for kneading and molding an ethylene-vinyl acetate copolymer, polyethylene, an organic peroxide and a coloring agent, the kneading is performed at X°C, a low temperature decomposition organic peroxide A having a 10-hour half life of a°C, and a high temperature decomposition organic peroxide B having a 10-hour half life of b°C are used as the organic peroxide. The X°C, a°C and b°C satisfy the relation of following formulae; :a°C<X°C-30°C(I), b°C>X°C-20°C(II), and the blending quantity of the low temperature decomposition organic peroxide A is 0.05-1.0 pts.mass for the total quantity 100 pts.mass of the ethylene-vinyl acetate copolymer and polyethylene.

Description

  The present invention relates to a method for producing a sealing film for a solar cell containing a mixture of EVA and polyethylene. Moreover, this invention relates to the sealing film for solar cells manufactured by this manufacturing method, and the manufacturing method of a solar cell using the same.

  In recent years, solar cells that directly convert sunlight into electrical energy have been widely used from the viewpoint of effective use of resources and prevention of environmental pollution, and further development has been promoted in terms of durability and power generation efficiency.

  As the structure of the solar cell, for example, as shown in FIG. 1, the light receiving surface side transparent protective member 11 made of a glass substrate or the like, the light receiving surface side sealing film 13A, the power generation element 14 such as a silicon crystal cell, the back surface side sealing, etc. A structure in which the stop film 13B and the back surface side protection member (back cover) 12 are laminated in this order and bonded and integrated is known.

  In solar cells, a plurality of power generating elements 14 are connected by connection tabs 15 in order to obtain a high electrical output. Therefore, in order to ensure the insulation of the power generation element 14, the power generation element is sealed using the sealing films 13A and 13B having insulation properties.

  Further, in order to make sunlight incident on the solar cell enter the power generation element 14 as efficiently as possible, a colored sealing film colored white or the like is used as the sealing film 13B disposed on the back surface side, and the space between the power generation elements is The power generation efficiency is improved by reflecting the sunlight that has passed through and reaching the colored sealing film to be incident on the power generation element 14 (Patent Document 1).

  As a sealing film used for these solar cells, a film made of an ethylene-polar monomer copolymer such as ethylene-vinyl acetate copolymer (hereinafter also referred to as EVA), ethylene-ethyl acrylate copolymer (EEA), etc. Is conventionally used. In particular, EVA films are preferably used because they are inexpensive and have high transparency. The EVA film for sealing film contains an organic peroxide in addition to EVA in order to improve the film strength and durability, and crosslinks EVA when integrated with other members. It is common.

  In recent years, in order to suppress the shrinkage | contraction of the sealing film which arises in the heating process at the time of solar cell preparation, the sealing film for solar cells produced using the resin mixture of EVA and polyethylene is developed (patent document 2). ). Patent Document 3 describes that a kneaded composition is molded so that EVA is a continuous phase and polyethylene is a dispersed phase in order to improve the processability of a resin mixture of EVA and polyethylene.

JP 2009-239277 A JP 2013-175721 A JP 2013-175704 A

  When a colored sealing film is used as the sealing film on the back side, the colored sealing film 13B melted by heating is received by the power generation element 14 as shown in FIG. There is a case where it wraps around the surface side (this phenomenon is hereinafter referred to as wraparound). When the wraparound occurs, there is a problem that not only the amount of sunlight incident on the power generation element is reduced, but also the appearance of the solar cell is deteriorated.

  The colored encapsulating film using both EVA and polyethylene has a higher melting point than that of the EVA-only encapsulating film. Depending on the conditions (temperature etc.) at the time of carrying out, the viscosity of polyethylene may fall significantly and a wraparound may generate | occur | produce. On the other hand, depending on the characteristics of the polyethylene used, kneading with EVA may be difficult during production of the sealing film, or undissolved residue may be generated.

  Accordingly, an object of the present invention is to provide a method for producing a solar cell encapsulating film that is capable of producing a solar cell encapsulating film that is unlikely to wrap around during the production of the solar cell without causing undissolved residue. There is.

The above purpose is
A method for producing a sealing film for a solar cell, comprising a step of kneading and molding an ethylene-vinyl acetate copolymer, polyethylene, an organic peroxide and a colorant,
The kneading is performed at X ° C.
As the organic peroxide, a low-temperature decomposition type organic peroxide A having a 10-hour half-life temperature of a ° C. and a high-temperature decomposition type organic peroxide B having a 10-hour half-life temperature of b ° C. are used.
X ° C, a ° C and b ° C are the following formulas (I) and <II>:
a ° C <X ° C-30 ° C (I)
b ° C> X ° C-20 ° C (II)
The filling,
The compounding amount of the low temperature decomposition type organic peroxide A is more than 0.05 parts by mass and less than 1.0 parts by mass with respect to 100 parts by mass of the total amount of the ethylene-vinyl acetate copolymer and polyethylene. It is achieved by the manufacturing method of the sealing film for solar cells.

  In this way, by using two types of organic peroxides having different reaction temperatures and reacting the low-temperature decomposition type organic peroxide A during kneading to crosslink polyethylene and EVA to a certain degree, the melting point of the polyethylene is exceeded. The drop in the viscosity is reduced. This suppresses a rapid drop in the viscosity of the colored encapsulating film melt during heating to integrate the solar cell components during solar cell fabrication, and wraps around the light receiving surface of the power generation element. Can be prevented. Moreover, since the film forming range is expanded by reducing the drop in viscosity, a sealing film with few defects can be manufactured with high efficiency. The high-temperature decomposable organic peroxide B remains in the produced sealing film and reacts by heating when the solar cell members are integrated to further crosslink the EVA and polyethylene cross-linked to a predetermined extent. .

Preferred embodiments of the present invention are as follows.
(1) The melt mass flow rate (MFR) of the polyethylene is 20 to 100 g / 10 min.
(2) Melting | fusing point of the said polyethylene is 90-120 degreeC.
(3) The melt mass flow rate (MFR) of the ethylene-vinyl acetate copolymer is 1 to 35 g / 10 min.
(4) The mass ratio (EVA: PE) of the ethylene-vinyl acetate copolymer and polyethylene is 8: 2 to 3: 7.
(5) a ° C is 35 to 80 ° C.
(6) bC is 80-120C.
(7) X ° C is 90 to 130 ° C.
(8) The compounding quantity of the high temperature decomposition type organic peroxide B is 0.5-2 mass parts with respect to 100 mass parts of total mass of the said ethylene-vinyl acetate copolymer and polyethylene.

  Moreover, this invention provides the sealing film for solar cells manufactured by the manufacturing method of the sealing film for solar cells of this invention.

Furthermore, the present invention provides a laminate by laminating a light-receiving surface-side transparent protective member, a light-receiving surface-side sealing film, a power generation element, a back-side colored sealing film, and a back-side protective member in this order, and the laminate In the manufacturing method of the solar cell module including the process of integrating by pressurizing and heating,
The solar cell module manufacturing method is characterized in that the solar cell sealing film is used as the back side colored sealing film.

  The sealing film for solar cells manufactured by the manufacturing method of the present invention does not cause a significant decrease in viscosity when heated to a high temperature. Therefore, when the solar cell members are integrated, the sealing film melted by heating It is possible to prevent the film from wrapping around the light receiving surface of the power generation element. Therefore, by using this solar cell sealing film, it is possible to obtain a solar cell in which deterioration of power generation efficiency and appearance due to wraparound is prevented.

It is a schematic sectional drawing which shows a common solar cell. It is the schematic which shows a mode that each member of a solar cell is integrated using a vacuum laminator. It is a top view of the electric power generation element which shows the mode of wraparound.

Hereinafter, the present invention will be described in detail. The manufacturing method of the sealing film for solar cells of this invention includes the process of knead | mixing and shape | molding EVA, polyethylene, an organic peroxide, and a coloring agent. As the organic peroxide, a low-temperature decomposition type organic peroxide A having a 10-hour half-life temperature of a ° C. (hereinafter simply referred to as “organic peroxide A”) and a 10-hour half-life temperature of b ° C. A high-temperature decomposition type organic peroxide B (hereinafter also simply referred to as “organic peroxide B”) is used. When the kneading temperature is X ° C., the relationship between the organic peroxide A 10-hour half-life temperature a ° C. and the organic peroxide B 10-hour half-life temperature b ° C. is as follows:
a ° C <X ° C-30 ° C (I)
b ° C> X ° C-20 ° C (II)
Meet.

  The compounding amount of the organic peroxide A is more than 0.05 parts by weight and less than 1 part by weight, preferably 0.08 to 0.7 parts by weight, and more preferably 0.1 parts per 100 parts by weight in total of EVA and polyethylene. -0.5 mass part. If it is less than this range, crosslinking during kneading may be insufficient and wraparound may not be sufficiently prevented, and if it exceeds this range, crosslinking may be excessively performed during kneading and film formation may be difficult.

  On the other hand, the compounding quantity of the organic peroxide B becomes like this. Preferably it is 0.5-2 mass parts, More preferably, it is 0.7-1.5 mass parts. If it is this range, it is possible to further crosslink EVA and polyethylene that have been cross-linked to a predetermined degree during kneading by heating when integrating the solar cell members, and to firmly integrate the solar cell members. is there.

  The blending amount of the organic peroxide A is preferably smaller than the blending amount of the organic peroxide B, and the mass ratio of the organic peroxide A to the organic peroxide B (organic peroxide A / organic peroxide B) ) Is 0.06 to 0.9, preferably 0.08 to 0.7, particularly preferably 0.1 to 0.5.

  As described above, the organic peroxide A reacts at the time of kneading at X ° C. to crosslink EVA and polyethylene to a predetermined extent. The kneading temperature X ° C. is preferably higher than the melting point of polyethylene, for example, 90 to 130 ° C., preferably 95 to 120 ° C. If it is this range, the melt | dissolution residue of polyethylene and EVA will not arise, but each component can be mixed uniformly.

  Specifically, the 10-hour half-life temperature a ° C of the organic peroxide A is, for example, 35 to 80 ° C, and preferably 40 to 75 ° C. Further, the 10-hour half-life temperature b ° C. of the organic peroxide B is specifically 80 to 120 ° C., preferably 90 to 110 ° C., for example. Further, the difference (b−a) between b ° C. and a ° C. is preferably 15 ° C. or more, particularly preferably 20 ° C. or more. This facilitates temperature control during kneading.

  Specific types of the organic peroxide A and the organic peroxide B are selected so as to satisfy the relationship of the above formulas (I) and (II) according to the kneading temperature. Specific examples include the following organic peroxides.

  For example, benzoyl peroxide type curing agent, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, 3,5,5-trimethylhexanoyl peroxide, di-n-octanoyl peroxide, lauroyl peroxide, Stearoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, succinic acid peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, tert-hexylperoxy-2-ethyl Hexanoate, 4-methylbenzoyl peroxy Id, tert-butylperoxy-2-ethylhexanoate, m-toluoyl + benzoyl peroxide, benzoyl peroxide, 1,1-bis (tert-butylperoxy) -2-methylcyclohexanate, 1,1 -Bis (tert-hexylperoxy) -3,3,5-trimethylcyclohexanate, 1,1-bis (tert-hexylperoxy) cyclohexanate, 1,1-bis (tert-butylperoxy)- 3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane, 1,1-bis ( tert-butylperoxy) cyclododecane, tert-hexylperoxyisop Pyrmonocarbonate, tert-butylperoxymaleic acid, tert-butylperoxy-3,3,5-trimethylhexane, tert-butylperoxylaurate, 2,5-dimethyl-2,5-di (methylbenzoyl) Peroxy) hexane, tert-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexyl monocarbonate, tert-hexylperoxybenzoate, 2,5-di-methyl-2,5-di (benzoylperoxy) ) Hexane, t-butylperoxy-2-ethylhexyl monocarbonate and the like.

  Examples of the benzoyl peroxide curing agent include benzoyl peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, p-chlorobenzoyl peroxide, m-toluoyl peroxide, and 2,4-dichloro. Examples include benzoyl peroxide and t-butyl peroxybenzoate. The benzoyl peroxide curing agent may be used alone or in combination of two or more.

  Preferred as the organic peroxide A is 1,1,3,3-tetramethylbutylperoxyneodecanoate, dilauroyl peroxide, t-butylperoxy-2-ethylhexanoate, dibenzoyl peroxide. Etc. Moreover, what is preferable as organic peroxide B includes t-butylperoxy-2-ethylhexyl monocarbonate and the like. Each of the organic peroxides A and B may be used alone or in combination of two or more.

  In the present invention, the mass ratio of EVA and PE (EVA: PE) is preferably 8: 2 to 3: 7, and particularly preferably 7: 3 to 4: 6. If it is this range, while the thermal contraction of a sealing film will be suppressed, the sealing film for solar cells which is excellent in adhesiveness and durability will be obtained.

  Polyethylene (PE) is a polymer mainly composed of ethylene as defined in JIS, and is a homopolymer of ethylene, ethylene and an α-olefin having 3 or more carbon atoms of 5 mol% or less, especially 3 to 8 (for example, Butene-1, hexene-1, 4-methylpentene-1, octene-1, etc.), and ethylene and a non-olefin monomer of 1 mol% or less having only carbon, oxygen and hydrogen atoms in the functional group (JIS K6922-1: 1997).

  Polyethylene is generally classified according to its density, and examples thereof include high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE).

LDPE generally has a long chain branch obtained by polymerizing ethylene in the presence of a radical generator such as an organic peroxide under a high pressure of 100 to 350 MPa, and its density (according to JIS K7112 applies hereinafter). Is generally 0.910 g / cm ³ or more and less than 0.930 g / cm ³ .

LLDPE is generally obtained by copolymerizing ethylene and an α-olefin in the presence of a transition metal catalyst such as a Ziegler type catalyst, a Phillips catalyst, or a metallocene type catalyst, and its density is generally 0.910 to 0. .940 g / cm ³ , preferably 0.910 to 0.930 g / cm ³ .

HDPE is a polyethylene whose density is generally between 0.942 and 0.970 g / cm ³ . In the present invention, LDPE or LLDPE is preferable from the viewpoint of film forming property, and LDPE is particularly preferable.

  The melting point of polyethylene is preferably 90 to 120 ° C., particularly preferably 95 to 110 ° C., from the viewpoint of preventing wraparound.

  The melt mass flow rate (MFR) of polyethylene is 20 to 100 g / 10 min, preferably 24 to 70 g / min. If it is lower than this range, unevenness in the thickness of the produced sealing film tends to occur, and if it is higher than this range, kneading becomes difficult. The melt mass flow rate (MFR) of polyethylene refers to a value measured according to JIS K6922-2.

  The content of vinyl acetate in the ethylene-vinyl acetate copolymer (EVA) is 20 to 35% by mass, preferably 22 to 32% by mass, particularly preferably 24 to 28% by mass. If the vinyl acetate content is lower than this range, sufficient adhesion as a sealing film may not be obtained. If it is higher than this range, the melting point may decrease and the degree of thermal shrinkage may increase.

  The melt mass flow rate (MFR) of EVA is desirably lower than that of polyethylene, for example, 1 to 35 g / 10 min, particularly 2 to 20 g / 10 min, and more preferably 2 to 10 g / 10 min. If it is this range, it can mix uniformly with polyethylene. EVA melt mass flow rate (MFR) refers to a value measured according to JIS K6924-1.

  The melting point of EVA is desirably lower than the melting point of polyethylene. For example, it is preferably 60 to 90 ° C, particularly 65 to 80 ° C. If it is this range, workability will become favorable, the thickness nonuniformity of a sealing film will also be suppressed, and productivity will improve. In the present invention, the melting points of polyethylene and EVA refer to melting peak temperatures in DSC (differential scanning calorimetry) determined according to JIS K7121.

  Moreover, in this invention, in addition to EVA, polyethylene, the organic peroxide mentioned above, and a coloring agent, you may mix | blend and knead | mix a crosslinking adjuvant. The crosslinking aid can improve the crosslinking density and improve the adhesiveness, heat resistance and durability of the solar cell sealing film.

  The crosslinking aid is preferably used in an amount of 0.1 to 3.0 parts by mass, more preferably 0.2 to 2.5 parts by mass with respect to 100 parts by mass in total of EVA and PE. With such an amount of the crosslinking aid, it is possible to improve the crosslinking density without generating gas due to the addition of the crosslinking aid.

  Examples of the crosslinking aid (compound having a radical polymerizable group as a functional group) include trifunctional crosslinking aids such as triallyl cyanurate and triallyl isocyanurate, and (meth) acrylic esters (eg, NK ester). And monofunctional or bifunctional crosslinking aids. Of these, triallyl cyanurate and triallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

  Moreover, in this invention, in addition to each component mentioned above, you may mix | blend and knead | mix an adhesive improvement agent further. A silane coupling agent can be used as the adhesion improver. Thereby, it becomes possible to form the sealing film for solar cells which has the outstanding adhesive force. As silane coupling agents, γ-chloropropylmethoxysilane, vinylethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane , Γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- Mention may be made of (aminoethyl) -γ-aminopropyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more. Of these, γ-methacryloxypropyltrimethoxysilane is particularly preferred.

  The compounding amount of the adhesion improver is preferably 5 parts by mass or less, particularly 0.1 to 2 parts by mass with respect to 100 parts by mass in total of EVA and PE.

  In the present invention, the colorant is appropriately selected so that a desired color tone and sunlight reflectance can be obtained. For example, a white colorant such as titanium white (titanium dioxide) or calcium carbonate; a blue colorant such as ultramarine; Black colorants such as carbon black; milky white colorants such as glass beads and light diffusing agents can be used. Preferably, a white colorant based on titanium white can be used.

  The blending amount of the colorant is generally 0.1 to 10 parts by weight, more preferably 1 to 6 parts by weight with respect to 100 parts by weight of EVA and polyethylene in total.

  In the present invention, in addition to EVA, polyethylene, organic peroxide and colorant, various physical properties of the film (optical properties such as mechanical strength, transparency, heat resistance, light resistance, crosslinking rate, etc.) Various additives such as a plasticizer, an acryloxy group-containing compound, a methacryloxy group-containing compound and / or an epoxy group-containing compound may be further blended and kneaded as necessary for adjustment, particularly improvement in mechanical strength. .

  As described above, the present invention includes a step of kneading and molding EVA, polyethylene, organic peroxides A and B, a colorant, and, if necessary, other components described above. The kneading is performed at a temperature of X ° C. by melting and mixing EVA and polyethylene. The temperature X ° C. is a temperature at which the low temperature decomposition type organic peroxide A reacts and the high temperature decomposition type organic peroxide B does not react or hardly reacts. Therefore, at the time of kneading, the low-temperature decomposition type organic peroxide A decomposes to generate radicals, and EVA and polyethylene are crosslinked to some extent. The specific temperature range of the kneading temperature X ° C. is, for example, 90 to 130 ° C., preferably 95 to 120 ° C. as described above. The kneading time is preferably, for example, 1 minute to 30 minutes, particularly 2 minutes to 5 minutes. The kneading can be performed by a conventionally known kneader such as a roll mill, a Banbury mixer, a twin screw extruder or the like.

  As a method for forming the kneaded material into a sheet, it may be performed according to a conventionally known method. For example, it can be produced by a method of obtaining a sheet by molding by ordinary calendar molding (calendering) or extrusion molding.

  The present invention is particularly suitable when molding is performed by calendar molding. In the case of molding by calendar molding, first, EVA, polyethylene, organic peroxides A and B, colorants and, if necessary, other components described above are kneaded with a kneader such as the above-described roll mill, and then kneaded. Is rolled to a desired thickness with a plurality of calendar rolls arranged in an L shape or the like. After rolling, the solar cell sealing film is obtained by cooling through a cooling roll and winding up appropriately. The film forming temperature for forming the kneaded kneaded material into a sheet is a temperature at which the high-temperature decomposable organic peroxide B does not react or hardly reacts, and is, for example, 70 to 90 ° C.

  The thickness of the solar cell sealing film is not particularly limited, but is 0.05 to 2 mm, preferably 0.3 to 0.8 mm.

  Next, a method for producing a solar cell module using the colored sealing film produced by the production method of the present invention will be described. As shown in FIG. 1, the manufacturing method of the solar cell module of the present invention includes a light receiving surface side transparent protective member 11, a light receiving surface side sealing film 13A, a power generation element 14, a back surface side colored sealing film 13B and a back surface. The laminated body 10 is obtained by laminating the side protection members 12 in this order, and the laminated body 10 is integrated by pressurizing and heating. This step of pressurizing and heating the laminate 10 is preferably performed using, for example, a vacuum laminator having an inflatable diaphragm, particularly a vacuum laminator of the double vacuum chamber system shown in FIG.

  A vacuum laminator 100 shown in FIG. 2 includes an upper chamber 102 having a diaphragm 103 and a lower chamber 101 having a mounting table 105 for mounting the stacked body 10. In the vacuum laminator 100, the laminated body 10 is pressurized by the diaphragm 103 after evacuating the upper chamber 102 and the lower chamber 101. The evacuation in the upper chamber 102 and the lower chamber 101 is performed by dividing the lower chamber vacuum pump 107 connected to the lower chamber exhaust port 106 and the upper chamber vacuum pump 109 connected to the upper chamber exhaust port 108. Is done.

  In order to pressurize the laminated body 10 using such a vacuum laminator, first, the light receiving surface side transparent protective member 11, the light receiving surface side sealing film 13 </ b> A are placed on the mounting table 105 provided in the lower chamber 101. The laminated body 10 which laminated | stacked the electric power generation element 14, the back surface side colored sealing film 13B of this invention, and the back surface side protection member 12 in this order is mounted. Next, after the upper chamber 102 and the lower chamber 101 are evacuated by the upper chamber vacuum pump 109 and the lower chamber vacuum pump 107, respectively, the inside of the upper chamber 102 is preferably set to a pressure equal to or higher than the atmospheric pressure. . Thereby, the uppermost surface of the laminated body 10 is pressed by the diaphragm 103, and the laminated body 10 is pressurized. For the light-receiving surface side sealing film 13, a highly transparent sealing film that is not colored is used.

  In order to make each of the upper chamber 102 and the lower chamber 101 vacuum, it is preferable that the upper chamber 102 and the lower chamber 101 are first depressurized to 50 to 150 Pa, particularly 50 to 100 Pa, respectively. The vacuum time is, for example, 0.1 to 5 minutes. Then, the laminated body is uniformly pressed by the diaphragm 103 by setting the inside of the upper chamber to 40 to 110 kPa, particularly 60 to 105 kPa.

It is preferable to adjust the degree of expansion of the diaphragm so that the laminate is pressurized at a pressure of 1.0 × 10 ³ Pa to 5.0 × 10 ⁷ Pa, particularly 60 to 105 kPa. The pressing time is, for example, 5 to 15 minutes.

  In the method of the present invention, heating is performed together with pressurization. As a heating method, the entire vacuum laminator 100 shown in FIG. 2 is heated in a high-temperature environment such as an oven, and a heating medium such as a heating plate is introduced into the lower chamber 101 of the vacuum laminator 100 shown in FIG. The method of heating the body 10 etc. are mentioned. In the latter method, for example, a heating plate is used as the mounting table 105, a heating plate is arranged on the upper side and / or lower side of the mounting table 105, or a heating plate is arranged on the upper side and / or lower side of the stacked body. It is done by doing.

  Among these heating methods, it is preferable to heat from the light-receiving surface side transparent protective member 11 side by using a heating plate as the mounting table 105. Thereby, the heat transfer to the light-receiving surface side sealing film 13B is performed earlier than the back-side colored sealing film 13B, so that the light-receiving surface-side sealing film 13A is relative to the back-side colored sealing film 13B. Since it melts quickly and comes into close contact with the light receiving surface of the power generation element 14, it is possible to prevent the wraparound more reliably.

  The laminated body 10 is preferably heated to a temperature of, for example, 130 to 170 ° C, preferably 140 to 160 ° C. The pressurization by the diaphragm is usually started in the middle of heating by heating.

  Thus, after performing a heating and pressurization, a solar cell is obtained by cooling. In the present invention, as described above, in the process of producing the solar cell sealing film, the low-temperature decomposable organic peroxide A reacts to crosslink EVA and polyethylene to some extent, thereby causing an extremely low viscosity due to heating. Therefore, it is possible to prevent the melt of the back side colored sealing film from flowing around the light receiving surface of the power generation element during the heating and pressurization when manufacturing the solar cell. In addition, by using EVA and polyethylene in combination, the shrinkage of the sealing film that occurs during heating when the solar cell members are integrated can be suppressed. Can do.

  The light-receiving surface side transparent protective member 11 is usually a glass substrate such as silicate glass. As for the thickness of a glass substrate, 0.1-10 mm is common, and 0.3-5 mm is preferable. The glass substrate may generally be chemically or thermally strengthened.

  The back surface side protective member 12 used in the present invention is preferably a plastic film such as polyethylene terephthalate (PET). The back side protective member 12 may contain a white pigment. Thereby, the sunlight which permeate | transmits can be reflected and can be entered in an electric power generation element, and electric power generation efficiency improves. A film obtained by laminating a fluorinated polyethylene film, particularly a fluorinated polyethylene film / Al / fluorinated polyethylene film in this order in consideration of heat resistance and wet heat resistance.

  The power generating element used in the solar cell module performs photoelectric conversion, and a conventionally known semiconductor substrate is used. As the semiconductor substrate, an optical semiconductor element composed of single crystal, polycrystal, or amorphous is used. Specifically, amorphous silicon a-Si, hydrogenated amorphous silicon a-Si: H, hydrogenated amorphous silicon carbide a-SiC: H, amorphous silicon nitride, etc. Amorphous or microcrystalline amorphous silicon semiconductors composed of alloys with other elements such as carbon, germanium, tin, etc. are pin-type, nip-type, ni-type, pn-type, MIS-type, heterojunction-type, homojunction A semiconductor layer configured as a mold, a Schottky barrier type, or a combination of these is used. In addition, the optical semiconductor layer may be CdS-based, GaAs-based, InP-based, or the like.

  What is necessary is just to perform according to a conventionally well-known method when incorporating a power generation element in a solar cell module. For example, an inner lead such as copper foil applied by solder plating is connected to the electrode of the power generation element, and the power generation element is connected in series and parallel with the inner lead so that a predetermined electrical output can be taken out from the solar cell module. To do.

  Hereinafter, the present invention will be described with reference to examples.

  Each material was supplied to a roll mill with the formulation shown in the following table, and kneaded at 110 ° C. to prepare a solar cell sealing film composition. This solar cell sealing film composition was calendered at 85 ° C., allowed to cool, and then a colored solar cell sealing film (0.5 mm) was obtained.

1. Light-receiving surface side transparent protective member (white plate tempered glass (with emboss), 230 mm × 230 mm × 3.2 mm) / light-receiving surface side sealing film (230 mm × 230 mm) / power generation element (single crystal silicon cell: 125 mm × 125 mm, thickness 220 mm) / the back side colored sealing film (230 × 230 mm) / back side protection member (TPT (Tedlar / PET / Tedlar: Model No. 2442) manufactured by Isovolta, 230 mm × 230 mm, thickness: 350 μm) in this order Laminated.

  The obtained laminate was subjected to a vacuum (degassing) time of 5 minutes, a pressure of 0.1 MPa and a press time of 15 minutes at 145 ° C. in a double vacuum chamber type vacuum laminator equipped with a diaphragm of the type shown in FIG. The solar cell module was produced by bonding and integration.

  About the produced solar cell module, the length which the back surface side colored sealing film wraps most on the power generation element was measured. A power generation element having a substantially rectangular shape has a wraparound length of 300 μm or less ○, only one side exceeds 300 μm, the remaining three sides are 300 μm or less Δ, and two or more sides exceed 300 μm X.

  The light-receiving surface side sealing film was obtained by feeding the material having the following composition to a roll mill and kneading at 70 ° C., followed by calendering at 70 ° C. (thickness 0.5 mm).

(Combination)
・ Ethylene-vinyl acetate copolymer (vinyl acetate content: 26 mass%, MFR: 4.3 g / 10 min) 100 mass parts ・ Crosslinking agent (t-butylperoxy-2-ethylhexyl monocarbonate) 1 mass part ・ Crosslinking Auxiliary agent (triallyl isocyanurate) 1.5 parts by mass ・ Silane coupling agent (γ-methacryloxypropyltrimethoxysilane)
0.3 parts by mass

2. Durability Test A laminate obtained by sandwiching the solar cell sealing film (900 mm × 1800 mm) between two 300 mm square glass plates was heated and pressurized at 150 ° C. for 10 minutes with a vacuum laminator to obtain a laminate. The laminate was allowed to stand for 1000 hours at a temperature of 85 ° C. and a relative humidity of 85%, and then the degree of peeling was determined. The case where there was no peeling was indicated as “◯”, the case where the peeling portion was 10 mm ² , and the case where the peeling portion was 10 mm ² or more.

3. Undissolved residue The presence or absence of undissolved polyethylene in the colored sealing film for solar cell produced above was visually confirmed. The number of 10 or less per 400 mm ² was evaluated as “◯”, and the number exceeding 10 per 400 mm ² was evaluated as “x”.

  The results are shown in the table below.

Details of the materials in the above table are as follows.
EVA: vinyl acetate content 26 mass%, MFR 4.3 g / 10 min, melting point 76 ° C.
PE (1): LDPE, MFR 70 g / 10 min, melting point 102 ° C., density 0.916 g / cm ³ (Tosoh Petrocene 249)
PE (2): LDPE, MFR 24 g / 10 min, melting point 106 ° C., density 0.918 g / cm ³ (Tosoh Petrocene 202)
Organic peroxide (1): t-butylperoxy-2-ethylhexyl monocarbonate
(10 hours half-life temperature 99 ° C, NOF Perbutyl E)
Organic peroxide (2): 1,1,3,3-tetramethylbutylperoxyneodecanoate
(10-hour half-life temperature 40.7 ° C, NOF perocta ND)
Organic peroxide (3): Dilauroyl peroxide
(10 hour half-life temperature 61.6 ° C, NOF Parroyl L)
Organic peroxide (4): t-butylperoxy-2-ethylhexanoate
(10-hour half-life temperature 72.1 ° C, NOF Perbutyl O)
Organic peroxide (5): Dibenzoyl peroxide
(10 hour half-life temperature 73.6 ° C, NOF nipper FF)
Organic peroxide (6): 1,1-di (t-butylperoxy) cyclohexane
(10-hour half-life temperature 90.7 ° C, NOF Perhexa C)
Crosslinking aid: triallyl isocyanurate adhesion improver: γ-methacryloxypropyltrimethoxysilane Colorant: titanium dioxide

11 light-receiving surface side transparent protective member 12 back surface side protective member 13A solar cell sealing film (light-receiving surface side sealing film)
13B Solar cell sealing film (back side sealing film)
14 Power generation element 15 Connection tab

Claims (11)

A method for producing a sealing film for a solar cell, comprising a step of kneading and molding an ethylene-vinyl acetate copolymer, polyethylene, an organic peroxide and a colorant,
The kneading is performed at X ° C.
As the organic peroxide, a low-temperature decomposition type organic peroxide A having a 10-hour half-life temperature of a ° C. and a high-temperature decomposition type organic peroxide B having a 10-hour half-life temperature of b ° C. are used.
X ° C, a ° C and b ° C are the following formulas (I) and <II>:
a ° C <X ° C-30 ° C (I)
b ° C> X ° C-20 ° C (II)
The filling,
The compounding amount of the low temperature decomposition type organic peroxide A is more than 0.05 parts by mass and less than 1.0 parts by mass with respect to 100 parts by mass of the total amount of the ethylene-vinyl acetate copolymer and polyethylene. The manufacturing method of the sealing film for solar cells.   The manufacturing method of Claim 1 whose melt mass flow rate (MFR) of the said polyethylene is 20-100 g / 10min.   The manufacturing method of Claim 1 or 2 whose melting | fusing point of the said polyethylene is 90-120 degreeC.   The manufacturing method of any one of Claims 1-3 whose melt mass flow rate (MFR) of the said ethylene-vinyl acetate copolymer is 1-35 g / 10min.   The manufacturing method of any one of Claims 1-4 whose mass ratio (EVA: PE) of the said ethylene- vinyl acetate copolymer and polyethylene is 8: 2 to 3: 7.   The manufacturing method according to any one of claims 1 to 5, wherein a ° C is 35 to 80 ° C.   The manufacturing method according to any one of claims 1 to 6, wherein b ° C is 80 to 120 ° C.   The manufacturing method according to any one of claims 1 to 7, wherein X ° C is 90 to 130 ° C.   The amount of the high-temperature decomposable organic peroxide B is 0.5 to 2 parts by mass with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer and polyethylene, respectively. The production method according to item.   The solar cell sealing film manufactured by the manufacturing method of any one of Claims 1-9. A laminated body is obtained by laminating the light-receiving surface side transparent protective member, the light-receiving surface side sealing film, the power generation element, the back surface side colored sealing film, and the back surface side protective member in this order, and pressurizing and heating the laminated body In the manufacturing method of the solar cell module including the process of integrating by
The method for manufacturing a solar cell module, wherein the solar cell sealing film according to claim 10 is used as the back side colored sealing film.

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