JP5879299B2 - Method for producing sealing film for solar cell and method for producing solar cell - Google Patents

Description

The present invention relates to a method for manufacturing a solar cell sealing film used for sealing a solar cell element of a solar cell and a method for manufacturing a solar cell .

  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 shown in FIG. 1, a solar cell generally includes a light receiving surface side transparent protective member 11 made of a glass substrate or the like, a light receiving surface side sealing film 13A, a solar cell 14 such as a silicon crystal power generation element, a back surface side seal. The stop film 13B and the back surface side protection member (back cover) 12 are laminated in this order, and after deaeration under reduced pressure, the light receiving surface side sealing film 13A and the back surface side sealing film 13B are cross-linked and cured to bond together. Is manufactured.

  Conventionally, as a sealing film used for a solar battery, an ethylene-polar monomer copolymer such as an ethylene-vinyl acetate copolymer (hereinafter also referred to as EVA) or an ethylene-ethyl acrylate copolymer (EEA) is used. A film is used. In particular, EVA films are preferably used because they are inexpensive and have high transparency.

  In recent years, various sealing films have been developed in order to further improve the sealing performance and water vapor permeation resistance of the sealing film for solar cells. For example, in Patent Document 1, at least one resin selected from an ethylene-vinyl acetate copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, and an ethylene-aliphatic unsaturated carboxylic acid ester copolymer, A sealing resin sheet (sealing film) containing a mixed resin composed of a thermoplastic resin (such as polyethylene) other than the resin is disclosed.

JP 2010-59277 A

  By the way, as a method of crosslinking the resin contained in the sealing film for solar cells, a method of crosslinking a sealing film containing an organic peroxide by heating, or irradiation of a sealing film not containing an organic peroxide with an electron beam There is a method of cross-linking. However, when two types of resins are used as in Patent Document 1, temperature control becomes difficult due to heat generated by shearing when the composition is kneaded in the process of producing the sealing film. When an organic peroxide is blended with two kinds of resins, there is a situation that the organic peroxide reacts during kneading and the crosslinking reaction proceeds unintentionally. Therefore, when two kinds of resins are used as the resin for the sealing film, it is necessary to produce the sealing film without blending the organic peroxide and to perform crosslinking by electron beam irradiation using an expensive apparatus. Is the current situation (see Patent Document 1, Examples 1 and 2). In order to solve this problem, a method in which two kinds of resins are first kneaded and the temperature can be adjusted and then an additive such as an organic peroxide is added and further kneaded can be considered. In the method, since the kneading process has two stages, not only the production efficiency is lowered, but also the generation of foreign matters due to the process length becomes a problem.

Accordingly, an object of the present invention is to efficiently and satisfactorily produce a solar cell encapsulating film containing two types of resins, even when the composition for production contains an organic peroxide. it is to provide a method for manufacturing a solar cell using the method of manufacturing a can Ru solar cell sealing film, as well as this.

The above object is a composition for producing a sealing film for a solar cell, comprising an ethylene-vinyl acetate copolymer, polyethylene and an organic peroxide,
The MFR defined in JIS K6922-1 of polyethylene is the 50g / 10min~90g / 10min, said ethylene - vinyl acetate content in the vinyl acetate copolymer is Ri 17-27% by mass, the organic peroxide Is 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane or tert-butylperoxy-2-ethylhexyl monocarbonate, a composition for producing a sealing film for solar cells Is achieved.

  Before the resin composition containing an organic peroxide is formed into a sheet, it is necessary to knead the resin and each additive at a temperature at which no cross-linking reaction occurs and no unmelted resin remains. In the present invention, by using the above specific ethylene-vinyl acetate copolymer and polyethylene, it is possible to form a film satisfactorily without causing a crosslinking reaction or unmelted resin during kneading. That is, if the MFR of polyethylene is within the above range, heat generation during kneading can be suppressed, so that the reaction of organic peroxide can be prevented, and unmelted polyethylene can be reduced. Furthermore, if the vinyl acetate content of EVA is in the above range, the sealing film can be efficiently mass-produced without sticking to the molding machine or peeling.

The preferable aspect of the composition for solar cell sealing film manufacture used for this invention is as follows.
(1) The polyethylene is LDPE having Mw / Mn of 4 or more.
(2) months is for render molding.

  Moreover, the said objective is achieved by the manufacturing method of the sealing film for solar cells including the process of shape | molding the kneaded material obtained by kneading the said composition for sealing film manufacturing for solar cells in a sheet form.

The preferable aspect of the manufacturing method of the sealing film for solar cells of this invention is as follows.
(1) Prior to the kneading, the ethylene-vinyl acetate copolymer, the polyethylene and the organic peroxide are premixed at a temperature lower than the kneading temperature.
(2) The premixing temperature is 40 to 60 ° C.
(3) The molding is performed by calendar molding.

  Furthermore, the present invention provides a solar cell sealing film manufactured by the above-described manufacturing method and a solar cell formed by sealing a power generating element with the solar cell sealing film.

According to the production method of engaging Ru solar cell sealing film of the present invention will be better film without crosslinking or melt remaining occurs in the manufacturing stage the solar cell sealing film containing an organic peroxide be able to. Therefore, it is possible to produce a solar cell sealing film having a high sealing property that can be heat-crosslinked with high quality and high efficiency.

It is a schematic sectional drawing of a common solar cell.

Hereinafter, the present invention will be described in detail. As described above, the composition for producing a sealing film for a solar cell used in the present invention is an ethylene-vinyl acetate copolymer (hereinafter also referred to as “EVA”) and polyethylene (hereinafter also referred to as “PE”). The vinyl acetate content of EVA is 17 to 27% by mass, and the MFR of polyethylene is more than 30 g / 10 min and 100 g / 10 min or less.

  The blending mass ratio (EVA: PE) of the ethylene-vinyl acetate copolymer and the polyethylene is preferably 8: 2 to 3: 7, and more preferably 6: 4 to 3: 7. If it is this range, the composition which a resin melt | dissolving residue does not produce easily will be obtained, and the adhesive performance as a sealing film can be ensured at a high level.

  In the present invention, the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 17 to 27% by mass, preferably 20 to 26% by mass. If it is this range, inconvenience, such as a composition sticking to the molding machine at the time of shape | molding in a sheet form, does not arise, but it can form into a favorable film. In particular, when molding by calender molding, if the vinyl acetate content is less than 17% by mass, the composition peels from the calender roll, and if it exceeds 27% by mass, the calender roll is stuck and produced continuously. It becomes difficult to do. In the present invention, the vinyl acetate content of EVA is a value measured by the method described in JIS K6924.

  The melt flow rate of the ethylene-vinyl acetate copolymer is preferably 3 to 25 g / 10 min, particularly 4 to 20 g / 10 min. If it is this range, the fluidity | liquidity suitable for film forming will be ensured and a sealing film can be manufactured still more efficiently. In the present invention, the EVA melt flow rate (MFR) value is measured in accordance with JIS K7210 under the conditions of 190 ° C. and a load of 21.18 N.

  The polyethylene used in the present invention is a polymer mainly composed of ethylene as defined in JIS. An ethylene homopolymer, ethylene and an α-olefin having 3 or more carbon atoms of 5 mol% or less (for example, butene-1). , Hexene-1,4-methylpentene-1, octene-1, etc.) and ethylene with 1 mol% or less non-olefin monomer having only carbon, oxygen and hydrogen atoms in the functional group A copolymer is included (JIS K6922-1: 1997). PE 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 . The polyethylene used in the present invention is preferably LDPE (low density polyethylene) having Mw / Mn of 4 or more. With such LDPE having a relatively wide molecular weight distribution, the temperature dependence of the viscosity becomes small, and temperature control during kneading becomes easy. The weight average molecular weight Mw of polyethylene is preferably 30000-250,000, and the number average molecular weight Mn is preferably 2000-25000.

  In the present invention, Mw and Mn are values calculated as standard polystyrene conversion values from an elution curve measured by gel permeation chromatography.

  In this invention, MFR prescribed | regulated to JISK6922-1 of polyethylene exceeds 30 g / 10min and is 100 g / 10min or less, Preferably it is 50-90 g / 10min. When it is 30 g / 10 min or less, unmelted residue is generated, and a portion where EVA and PE are not sufficiently mixed is generated, so that the adhesiveness and appearance of the obtained sealing film are deteriorated. If it exceeds 100 g / 10 min, the fluidity increases and it becomes impossible to form a film well.

  The melting points of polyethylene and EVA by DSC are each preferably 110 ° C. or less. If it is 110 degrees C or less, since the film forming apparatus controlled by water temperature control can be used, thickness can be controlled with high precision and a sealing film can be manufactured at low cost. The melting point in the present invention refers to a value measured using DSC according to JIS K7121.

The composition for producing a sealing film for solar cell before kneading used in the present invention contains an organic peroxide. Any organic peroxide can be used as long as it decomposes at a temperature of 100 ° C. or higher to generate radicals. The organic peroxide is generally selected in consideration of the film formation temperature, the adjustment conditions of the composition, the curing temperature, the heat resistance of the adherend, and the storage stability. In particular, the one having a decomposition temperature of 70 ° C. or more with a half-life of 10 hours is preferable.

  Examples of the organic peroxide include, from the viewpoint of resin processing temperature and storage stability, for example, benzoyl peroxide 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-methylethyl Peroxy-2-ethylhexanoate, tert-hexyl par Xyl-2-ethylhexanoate, 4-methylbenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, m-toluoyl + benzoyl peroxide, benzoyl peroxide, 1,1-bis (tert-butyl Peroxy) -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, 1,1-bis (tert-hexylperoxy)- 3,3,5-trimethylcyclohexane, 2,2-bis (4,4-di tert-butylperoxycyclohexyl) propane, 1,1-bis (tert-butylperoxy) cyclododecane, tert-hexylperoxyisopropyl monocarbonate, tert-butylperoxymaleic acid, tert-butylperoxy-3, 3,5-trimethylhexane, tert-butylperoxylaurate, 2,5-dimethyl-2,5-di (methylbenzoylperoxy) hexane, tert-butylperoxyisopropylmonocarbonate, tert-butylperoxy-2 -Ethylhexyl monocarbonate, tert-hexyl peroxybenzoate, 2,5-di-methyl-2,5-di (benzoylperoxy) hexane, and the like.

  As the benzoyl peroxide-based curing agent, any can be used as long as it decomposes at a temperature of 70 ° C. or higher to generate radicals, and those having a decomposition temperature of 50 hours or higher with a half-life of 10 hours are preferable, It can be appropriately selected in consideration of preparation conditions, film formation temperature, curing (bonding) temperature, heat resistance of the adherend, and storage stability. Usable benzoyl peroxide curing agents include, for example, benzoyl peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, p-chlorobenzoyl peroxide, m-toluoyl peroxide, 2, Examples include 4-dichlorobenzoyl peroxide and t-butyl peroxybenzoate. The benzoyl peroxide curing agent may be used alone or in combination of two or more.

  Among the above organic peroxides, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane or tert-butylperoxy-2-ethylhexyl monocarbonate is preferable, and tert-butylperoxy-2-particulate is particularly preferable. Ethylhexyl monocarbonate is preferred.

  Content of an organic peroxide is 0.1-5 mass parts normally with respect to 100 mass parts of total amounts of EVA and PE, Preferably it is 0.2-3 mass parts. If the content of the organic peroxide is small, the crosslinking speed may be lowered during the crosslinking and curing, and if the content is large, the compatibility with the copolymer may be deteriorated.

It is preferable that the composition for manufacturing a sealing film for a solar cell used in the present invention further contains a crosslinking aid. A crosslinking aid can improve the gel fraction of the sealing film for solar cells, and can improve the adhesiveness and durability.

  The content of the crosslinking aid is usually 0.1 to 5 parts by weight, preferably 0.1 to 3 parts by weight, and particularly preferably 0.5 to 2.5 parts by weight with respect to 100 parts by weight of the total amount of EVA and PE. Used in parts by mass. Thereby, the sealing film which the hardness after bridge | crosslinking improves further is obtained.

  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) ) Monofunctional or bifunctional crosslinking aids. Of these, triallyl cyanurate and triallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

The composition for producing a sealing film for a solar cell used in the present invention may further contain an adhesion improver. As the adhesion improver, a silane coupling agent can be used. For example, γ-chloropropyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyl Triacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane , Γ-aminopropyltriethoxysilane, and N-β- (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 content of the silane coupling agent is 5 parts by mass or less, preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the total amount of EVA and PE.

The composition for producing a sealing film for a solar cell used in the present invention improves or adjusts various physical properties of the film (optical properties such as mechanical strength and transparency, heat resistance, light resistance, crosslinking speed, etc.), in particular. 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 included as necessary for improving the mechanical strength.

Next, the manufacturing method of the sealing film for solar cells of this invention is demonstrated in detail. As described above, the method for manufacturing the solar cell sealing film of the present invention comprises the step of molding the kneaded product obtained by kneading the above solar cell sealing film composition for production into a sheet. In particular, in the present invention, before kneading, it is preferable to premix EVA, polyethylene and organic peroxide and, if necessary, other additives at a temperature lower than the kneading temperature. Thus, by performing preliminary mixing before kneading, additives such as organic peroxides penetrate into the resin, and a uniform sealing film can be obtained after film formation.

  Premixing can be performed with a mixer such as a commonly used mixer. Although the temperature of premixing changes also with kinds of resin to be used, it is preferable that it is 40-60 degreeC. If it is lower than this range, there is a possibility that the organic peroxide and other additives cannot be sufficiently permeated into EVA and PE. If it is higher than this range, the viscosity of the resin may be lowered and mixing may not be performed properly. is there. The premixing time is preferably 10 to 30 minutes. As a result, the organic peroxide and other additives are infiltrated into the resin (EVA and PE) uniformly.

  The kneading can be performed by a kneader such as a commonly used twin screw extruder. The kneading temperature is, for example, 100 to 120 ° C. When kneading is carried out with a twin-screw extruder, the barrel temperature is preferably 5 to 15 ° C. higher than the one-hour half-life temperature of the organic peroxide contained in the composition, and the L / D ratio is 15 The above is preferable.

Any method may be used for forming the kneaded material obtained by kneading into a sheet. For example, calendar molding, extrusion molding, press molding, or the like can be used. Particularly, in the case of calendering, the composition is or stick to the calender rolls, without peeling from the calender rolls, it is possible to perform good film. Therefore, the solar cell sealing film prepared composition can be advantageously used as a composition for calendering. Although the thickness of the sealing film for solar cells to manufacture is not specifically limited, For example, it is 0.05-2 mm.

The structure of the solar cell manufactured according to the present invention is not particularly limited as long as it includes a structure in which the solar cell element is sealed by the solar cell sealing film manufactured by the method of the present invention. For example, a structure in which the solar cell is sealed by interposing the solar cell sealing film of the present invention between the light-receiving surface side transparent protective member and the back surface side protective member so as to be bridged and integrated. It is done.

  In the solar cell, in order to sufficiently seal the power generation element, for example, as shown in FIG. 1, the light-receiving surface side transparent protective member 11, the light-receiving surface side sealing film 13A, the solar cell 14 and the back surface side sealing. The film 13B and the back surface side protection member 12 may be laminated, and the sealing film may be cross-linked and cured according to a conventional method such as heat and pressure.

In order to heat and pressurize, for example, a laminated body in which each member is laminated is heated in a vacuum laminator at a temperature of 135 to 180 ° C., a degassing time of 0.1 to 5 minutes, a press pressure of 0.1 to 1.5 kg / cm ² , What is necessary is just to heat-press in time 5 to 15 minutes. At the time of this heating and pressurization, the resin contained in the light-receiving surface side sealing film 13A and the back surface-side sealing film 13B is cross-linked so that the light-receiving surface passes through the light-receiving surface side sealing film 13A and the back surface side sealing film 13B. The side transparent protective member 11, the back side transparent member 12, and the solar cell element 14 can be integrated to seal the solar cell 14.

The solar cell sealing film manufactured according to the present invention is not limited to a solar cell using a single crystal or polycrystalline silicon crystal power generation element as shown in FIG. It can also be used for a sealing film of a thin film solar cell such as a solar cell and a copper indium selenide (CIS) solar cell. In this case, for example, a glass substrate, a polyimide substrate, a fluororesin-based transparent substrate or the like of the light-receiving surface-side transparent protective member chemical vapor deposition thin-film solar cell element layer formed by such a surface, the present invention The solar cell sealing film manufactured according to the present invention is formed on the solar cell element formed on the surface of the back side protective member, the structure in which the manufactured sealing film for the solar cell, the back side protective member are laminated, and bonded and integrated. A structure in which a stop film and a light-receiving surface side transparent protective member are laminated and bonded and integrated, or a light-receiving surface side transparent protective member, a light-receiving surface side sealing film, a thin-film solar cell element, a back surface side sealing film, and a back surface side protection Examples include a structure in which members are laminated in this order and bonded and integrated. In addition, in this invention, the cell for solar cells and a thin film solar cell element are named generically, and are called a solar cell element.

  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 protection member 12 is preferably a plastic film such as polyethylene terephthalate (PET) or polyamide. Further, 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 may be used.

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

  Charge the pelletized EVA and polyethylene into a mixer preheated to 40 ° C, add the following additives, increase the temperature of the mixture to 50 ° C over 15 minutes while mixing, and let the EVA and polyethylene penetrate into the mixture. It was. The composition for producing a sealing film for solar cells thus obtained is put into a twin screw extruder, the barrel temperature is set to 129 ° C., the composition is kneaded, and the kneaded product is formed into a sheet with a calendar molding machine. A solar cell sealing film (thickness 0.5 mm) was obtained. The kneading conditions are as follows. L / D ratio: 20, screw configuration: kneading disc, rotation speed: 80 rpm.

The blending mass ratio of EVA and polyethylene is shown in Table 1, and details of each material are as follows.
EVA1 (Tosoh Ultrasen UE515), vinyl acetate content: 6% by mass, MFR: 25 g / 10 min, melting point: 101 ° C.
EVA2 (Tosoh Ultrasen UE626), vinyl acetate content: 15% by mass, MFR: 3 g / 10 min, melting point: 90 ° C.
EVA3 (Tosoh Ultrasen UE633), vinyl acetate content: 20% by mass, MFR: 20 g / 10 min, melting point: 83 ° C.
EVA4 (Tosoh Ultrasen UE634), vinyl acetate content: 26% by mass, MFR: 4.3 g / 10 min, melting point: 76 ° C.
EVA5 (Tosoh Ultrasen UE720), vinyl acetate content: 28% by mass, MFR: 150 g / 10 min, melting point: 69 ° C.
EVA6 (Tosoh Ultrasen UE750), vinyl acetate content: 32% by mass, MFR: 30 g / 10 min, melting point: 66 ° C.
Polyethylene 1 (Tosoh Petrocene 228), LDPE, MFR: 1.5 g / 10 min, melting point: 111 ° C., Mw: 200000, Mn: 24000, Mw / Mn: 8.3
Polyethylene 2 (Tosoh Petrocene 208), LDPE, MFR: 23 g / 10 min, melting point: 111 ° C., Mw: 110000, Mn: 15000, Mw / Mn: 7.3
-Polyethylene 3 (Ube Maruzen Polyethylene J3519), LDPE, MFR: 35 g / 10 min, melting point: 108 ° C., Mw: 90000, Mn: 13000, Mw / Mn: 6.9
Polyethylene 4 (Tosoh Petrocene 249), LDPE, MFR: 70 g / 10 min, melting point: 102 ° C., Mw: 35000, Mn: 5000, Mw / Mn: 7
Polyethylene 5 (Tosoh Petrocene 353), LDPE, MFR: 145 g / 10 min, melting point: 100 ° C., Mw: 15000, Mn: 2000, Mw / Mn: 7.5
[Additive]
・ Organic peroxide (t-butylperoxy-2-ethylhexyl monocarbonate: 1.3 parts by weight perbutyl E, manufactured by Nippon Oil & Fats, 119 ° C.) ・ Crosslinking aid (triallyl isocyanurate: manufactured by Nippon Kasei Chemical) TAIC) 1.5 parts by mass. Adhesion improver (γ-methacryloxypropyltrimethoxysilane: KBM503 manufactured by Shin-Etsu Silicone) 0.3 parts by mass

<Evaluation method>
1. Unmelted residue About the sealing film for solar cells obtained as described above, the presence or absence of unmelted resin was visually confirmed. 0.8 mm in diameter ² or more melting what remainder is less than one / 300 mm ² "○", 0.8 mm in diameter ² or more melting remainder was what is one / 300 mm ² or more as "×".
2. Film forming property “○” indicates that continuous production was possible in one straight (8 hours) when the above calendar molding was performed, and “Δ” indicates that peeling occurred from the calendar roll during continuous production in one straight. The case where sticking occurred on the calendar roll during continuous production in one straight was designated as “x”.

  The evaluation results are shown in Table 1. In Table 1, combinations using polyethylene 3 or 4 and EVA 3 or 4 are examples, and others are comparative examples. In the table, the unit of VA% is “mass%”, the unit of MFR is “g / 10 min”, and the unit of melting point Tm is “° C.”.

<Evaluation results>
When polyethylene 3 (MFR: 35 g / 10 min) or polyethylene 4 (MFR: 70 g / 10 min) is used in combination with EVA 3 (VA%: 20% by mass) or EVA 4 (VA%: 26% by mass) It was confirmed that the organic peroxide did not react during kneading, and no unmelted residue was formed, and the film forming property was good. On the other hand, when polyethylene 1 and polyethylene 2 having a low MFR were used, unmelted residue was generated. It was confirmed that when polyethylene 5 having a high MFR was used, the film forming property was lowered. Moreover, when EVA1 and 2 with low VA% were used, the composition peeled from the calender roll and continuous production was not possible. Furthermore, when EVA5 and 6 with high VA% were used, sticking to a calendar roll occurred and continuous production was not possible.

DESCRIPTION OF SYMBOLS 11 Light-receiving surface side transparent protective member 12 Back surface side protective member 13A Light-receiving surface side sealing film 13B Back surface side sealing film 14 Cell for solar cells

Claims (7)

A kneaded product obtained by kneading a composition for producing a sealing film for solar cells is a method for producing a sealing film for solar cells comprising a step of forming a kneaded product into a sheet ,
As the composition for producing a sealing film for solar cells,
Including ethylene-vinyl acetate copolymer, polyethylene and organic peroxide,
MFR prescribed in JIS K6922-1 of the polyethylene is 50 g / 10 min to 90 g / 10 min,
The vinyl acetate content in the ethylene-vinyl acetate copolymer is 17-27% by mass,
The organic peroxide is 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane or tert-butylperoxy-2-ethylhexyl monocarbonate,
The blending mass ratio (EVA: PE) of the ethylene-vinyl acetate copolymer and polyethylene is 8: 2 to 3: 7,
The manufacturing method of the sealing film for solar cells using what the melting | fusing point by DSC measurement of the said ethylene-vinyl acetate copolymer and polyethylene is 110 degrees C or less, respectively, and the melting point of the said polyethylene is 102 degrees C or more . Prior to the kneading, the ethylene - vinyl acetate copolymer, a solar cell according to claim 1, wherein the premixing in the polyethylene and the organic peroxide the temperature lower than the temperature of the kneading Manufacturing method of sealing film. The temperature of the said premix is 40-60 degreeC, The manufacturing method of the sealing film for solar cells of Claim 2 characterized by the above-mentioned. The method for producing a sealing film for a solar cell according to any one of claims 1 to 3 , wherein the molding is performed by calendar molding. The method for producing a sealing film for a solar cell according to any one of claims 1 to 4, wherein an LDPE having an Mw / Mn of 4 or more is used as the polyethylene. For producing a sealing film for a solar cell, wherein the content of the organic peroxide is 0.1 parts by mass or more and 5 parts by mass or less 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 of any one of Claims 1-5 which uses a composition. Method of manufacturing a solar cell comprising a step of sealing the solar cell element with a sealing film for a solar cell manufactured by the manufacturing method according to any one of claims 1 to 6.

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