JP6277839B2 - Solar cell sealing material and solar cell module using the same - Google Patents

Description

  The present invention relates to a solar cell sealing material excellent in adhesiveness, heat resistance and transparency, and a solar cell module using the same.

  In recent years, with increasing awareness of environmental issues such as global warming, expectations are increasing especially for photovoltaic power generation in terms of its cleanliness and non-polluting properties.

  Photovoltaic power generation directly converts solar energy into electrical energy using a semiconductor (solar cell element) such as silicon or GaAs. Since the solar cell element is vulnerable to physical impact, oxygen, water, etc., it is necessary to protect it with a sealing material or a protective member. Therefore, in general, a module for solar power generation (solar cell module) includes a front side transparent protective member (glass or the like), a sealing material, a solar cell element, a sealing material, a back side protective member (back sheet), etc. Laminated and integrated. Here, the sealing material in contact with the solar cell element is required to have adhesion to the solar cell element and other protective members (glass, backsheet, etc.), heat resistance, transparency, and the like.

  As a raw material for the solar cell encapsulant, an ethylene-vinyl acetate copolymer (hereinafter sometimes abbreviated as EVA) is widely used from the viewpoints of flexibility, transparency and the like. However, EVA is inferior in heat resistance and durability when used in a natural environment for a long period of time, and has insufficient adhesion to various members constituting the solar cell module. Therefore, there is a technique (for example, Patent Document 1) in which EVA is crosslinked with a crosslinking agent such as an organic peroxide to improve heat resistance and durability. However, since a crosslinking step is required, the productivity of the solar cell module is inferior, and the adhesiveness is not sufficient.

  On the other hand, Patent Document 2 discloses a solar cell sealing material that contains EVA, an organic peroxide, and an ethylene / vinyl acetate / glycidyl (meth) acrylate copolymer and has excellent adhesion to various members. . However, also in this technique, since the bridge | crosslinking process of a sealing material is needed, it is inferior to the productivity of a solar cell module.

Further, in Patent Document 3, a solar cell containing an ethylene polymer having a melting point of 90 ° C. or more and an ethylene / glycidyl (meth) acrylate copolymer and having heat resistance and adhesion suitable for practical use without crosslinking. An encapsulant is disclosed. The sealing material disclosed in Patent Document 3 ensures heat resistance by using an ethylene polymer having a melting point of 90 ° C. or higher as a main component, and in the examples, is composed of an ethylene resin at 94 ° C. or higher. An encapsulant is disclosed. However, since an ethylene-based resin having a high melting point generally has high density and crystallinity and low transparency, it has been difficult to achieve both heat resistance and transparency at a high level in this blending design.

Japanese Patent Laid-Open No. 62-14111 JP-A-4-325553 JP 2011-108790 A

  Therefore, an object of the present invention is to provide a sealing material excellent in adhesiveness, heat resistance and transparency without crosslinking and a solar cell module using the same.

  As a result of intensive studies, the present inventors have at least one adhesive layer containing a specific polyolefin resin, a silane-modified polyolefin resin and an epoxy-modified polyolefin resin, and have a specific heat of crystal fusion. It has been found that the solar cell encapsulant has excellent adhesion to glass and solar cells, and is excellent in heat resistance and transparency, and has completed the present invention.

That is, the present invention relates to the following [1] to [6].
[1] A solar cell having one or more adhesive layers containing the following (A), (B-1) and (B-2) as outermost layers and satisfying the following condition (i) Sealing material,
(A) Polyolefin resin (B-1) Silane-modified polyolefin resin (B-2) Epoxy-modified polyolefin resin (i) having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry The crystal melting calorie (ΔH _{≧ 90 ° C.} ) measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 1.5-30 J / g.
[2] The above (B-1) contains a silane-modified polyethylene resin having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry. The solar cell encapsulant described,
[3] The above (B-2) contains an epoxy-modified polyethylene resin having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry, [1] or The solar cell encapsulant according to [2],
[4] The solar cell encapsulant according to any one of [1] to [3], wherein the adhesive layer further contains the following (C):
(C) Polyolefin resin having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry [5] and further having a layer other than the adhesive layer, The solar cell encapsulant according to any one of [1] to [4], comprising (D) and (E) and satisfying the following condition (ii):
(D) Polyolefin resin having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry (E) A melting point of 90 ° C. or more measured at a heating rate of 10 ° C./min in differential scanning calorimetry Polyolefin resin (ii) The heat of crystal fusion (ΔH _{≧ 90 ° C.} ) of _{90 °} C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 1.5-30 J / g.
[6] A solar cell module using the solar cell sealing material according to any one of [1] to [5].

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell sealing material which was excellent in the adhesiveness to glass or a photovoltaic cell, and was excellent in heat resistance and transparency, and a solar cell module using the same are obtained.

It is a figure which shows the calculation method of crystal melting calorie | heat amount (DELTA) Hm (> = X (degreeC)) of X degrees or more. It is a figure which shows the sample for a creep test at the time of evaluating heat resistance.

The present invention is described in detail below.
In the present specification, the term “main component” is intended to allow other components to be included within a range that does not impede the action / effect of the sealing material of the present invention. Further, this term does not limit the specific content, but it is 50% by mass or more, preferably 65% by mass or more, more preferably 80% by mass or more, and 100% by mass or less of the entire constituent components. A component that occupies a range.
The solar cell encapsulant of the present invention has one or more adhesive layers containing the following (A), (B-1) and (B-2), and satisfies the condition (i).
(A) Polyolefin resin having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry (B-1) Silane modified polyolefin resin (B-2) Epoxy modified polyolefin resin conditions (i) The crystal melting calorie (ΔH _{≧ 90 ° C.} ) measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 1.5-30 J / g.

<Resin constituting the adhesive layer>
(A) Polyolefin resin having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry The type of (A) used in the present invention is particularly limited as long as the melting point is less than 90 ° C. Although it is not a thing, it is preferable to make 1 type, or 2 or more types, such as a polyethylene-type resin, a polypropylene-type resin, and an ionomer, into a main component. Among these, a polyethylene resin is preferable from the viewpoint of excellent flexibility, weather resistance, and transparency. Examples of the polyethylene resin include ultra-low density polyethylene, low density polyethylene, and linear low density polyethylene (ethylene / α-olefin copolymer). Among these, an ethylene / α-olefin copolymer is preferable from the viewpoint of low crystallinity and excellent light transmittance and flexibility, and among these copolymers, an ethylene / α-olefin random copolymer is more preferable. (A) used for this invention may be used individually by 1 type, and may mix and use 2 or more types.

The ethylene / α-olefin copolymer is a copolymer of ethylene and α-olefin. Here, the kind of α-olefin copolymerized with ethylene is not particularly limited as long as the melting point of the ethylene / α-olefin copolymer can be ensured to be less than 90 ° C. Are preferably used, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 3- Examples include methyl-butene-1, 4-methyl-pentene-1, and the like. Among these, 1-butene, 1-hexene, or 1-octene is preferable from the viewpoint of industrial availability, economy, and the like. As the α-olefin copolymerized with ethylene, only one kind may be used alone, or two or more kinds may be used in combination at any ratio.
Further, the content of the monomer unit derived from α-olefin copolymerized with ethylene is not particularly limited as long as the melting point of the ethylene / α-olefin copolymer can be ensured to be less than 90 ° C. When the total monomer unit constituting the ethylene / α-olefin copolymer is 100% by mass, it is preferably 5 to 50% by mass, more preferably 10 to 45% by mass, and 15 to 15%. More preferably, it is 40 mass%. When the content of the monomer unit derived from α-olefin is 5% by mass or more, the crystallinity is reduced by the copolymer component, thereby improving transparency (for example, total light transmittance), The melting point can be lowered. In addition, if the content of the monomer unit derived from α-olefin is 50% by mass or less, when all the materials are mixed to produce a pellet, the occurrence of blocking of the raw material pellet is suppressed. preferable. In addition, the kind and content of the α-olefin copolymerized with ethylene can be analyzed by a well-known method, for example, a nuclear magnetic resonance (NMR) measuring apparatus or other instrumental analyzers.

  Further, the ethylene / α-olefin copolymer may contain other monomer units other than the monomer units derived from ethylene and α-olefin as long as the melting point can be ensured to be less than 90 ° C. . Examples of other monomers include acrylic acid esters, cyclic olefins, vinyl aromatic compounds (such as styrene), and polyene compounds. The content of other monomer units is preferably 20% by mass or less, and 15% by mass or less when the total monomer units in the ethylene / α-olefin copolymer is 100% by mass. It is more preferable.

  The melting point measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (A) used in the present invention is not particularly limited as long as it is less than 90 ° C., but the transparency and flexibility are good. In view of the above, it is more preferably 85 ° C. or lower, and further preferably 80 ° C. or lower. Moreover, it is preferable that it is 40 degreeC or more from viewpoints, such as blocking prevention of a sealing material, It is more preferable that it is 45 degreeC or more, It is further more preferable that it is 50 degreeC or more. In addition, 45-85 degreeC is preferable and the range of melting | fusing point measured by the heating rate of 10 degree-C / min in the differential scanning calorimetry of (A) used for this invention has more preferable 50-80 degreeC.

  Here, as reference values for the melting point, general-purpose high-density polyethylene (HDPE) is about 130 to 145 ° C., low-density polyethylene (LDPE) is about 100 to 125 ° C., general-purpose homopolypropylene is about 165 ° C., and general-purpose propylene. -Ethylene random copolymer is about 130-150 degreeC. The melting point can be measured using a differential scanning calorimeter at a heating rate of 10 ° C./min according to JIS K7121.

The crystal melting calorie measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (A) used in the present invention is preferably 5 J / g or more from the viewpoint of preventing blocking of the sealing material, More preferably, it is 10 J / g or more, and further preferably 20 J / g or more. Further, from the viewpoint of improving transparency and flexibility, it is preferably 90 J / g or less, more preferably 80 J / g or less, and further preferably 70 J / g or less. The range of the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (A) used in the present invention is preferably 5 to 90 J / g, and 10 to 80 J / g. More preferably, it is more preferably 20 to 70 J / g. The amount of heat of crystal melting can be measured by the method described in the Examples.
Further, the crystal melting calorie (ΔH _{≧ 90 ° C.} ) of _{90 °} C. or higher measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (A) used in the present invention improves transparency and flexibility. From the viewpoint, it is preferably 1.0 J / g or less, more preferably 0.1 J / g or less, and further preferably 0.01 J / g or less. Note that the heat of crystal melting at 90 ° C. or higher (ΔH _{≧ 90 ° C.} ) can be measured by the method described in Examples.

  The melt flow rate (load: 21.18 N, temperature: 190 ° C. (polyethylene resin), 230 ° C. (polypropylene resin)) according to JIS K7210 of (A) used in the present invention is the film forming property and sealing. From the viewpoint of heat resistance of the stopper, it is preferably 0.5 to 10 g / 10 min, and more preferably 1.0 to 5.0 g / 10 min.

The density of (A) used in the present invention, from the viewpoint of blocking prevention of the sealing material is preferably 0.865 g / cm ³ or more, 0.868 g / cm ³ or more, more preferably, 0.870 g / cm ³ The above is more preferable. Further, from the viewpoint of improving the transparency and flexibility, it is preferably less than 0.900 g / cm ^3, more preferably less than 0.895 g / cm ^3, more preferably less than 0.891 g / cm ^3. The density can be measured by the method described in the examples. The range of the density of (A) used in the present invention is preferably less than 0.865 g / cm ³ or more ^{0.900g / cm 3, 0.868g / cm} 3 or more 0.895 g / cm less than ³ more preferably, more preferably less than 0.870 g / cm ³ or more 0.891 g / cm ^3.

  In the adhesive layer of the solar cell encapsulant of the present invention, the content of (A) is preferably 40% by mass or more, more preferably 50% by mass or more, and 60% by mass in the adhesive layer from the viewpoints of flexibility and transparency. The above is more preferable. Moreover, from a heat resistant viewpoint, 98 mass% or less is preferable, 95 mass% or less is more preferable, and 90 mass% or less is further more preferable. In addition, the range of the content of (A) in the adhesive layer of the solar cell sealing material of the present invention is preferably 40 to 98% by mass in the adhesive layer, more preferably 50 to 95% by mass, More preferably, it is 60-90 mass%.

The manufacturing method of (A) used for this invention is not specifically limited, The well-known polymerization method using the well-known ethylene polymerization catalyst is employable.
Known polymerization methods include, for example, a slurry polymerization method, a solution polymerization method using a multisite catalyst typified by a Ziegler-Natta type catalyst, and a single site catalyst typified by a metallocene catalyst and a postmetallocene catalyst, Examples include a gas phase polymerization method, and a bulk polymerization method using a radical initiator.
(A) used in the present invention is preferably a relatively soft resin, but on the other hand, it is preferable that blocking of raw material pellets can be suppressed. For this reason, (A) is preferably produced using a single-site catalyst from which a low molecular weight component is small and a resin having a narrow molecular weight distribution can be obtained.
Note that (A) does not include a silane-modified polyolefin resin or an epoxy-modified polyolefin resin.

  Specific examples of (A) used in the present invention include trade names “Karnel” manufactured by Nippon Polyethylene, trade names “engage”, “affinity” manufactured by Dow Chemical, Trade names “TAFMER A”, “TAFMER P”, “TAFMER H” manufactured by Mitsui Chemicals, Inc., “LUCENE” manufactured by LG Chemical Co., etc., and the like.

(B-1) Silane-modified polyolefin resin

(B-1) used in the present invention is a polyolefin resin containing monomer units derived from a plurality of silane compounds in the molecule. As such a thing, the graft polymer which the silane compound graft-polymerized to polyolefin resin is mentioned. In the present invention, the content of (B-1) in the adhesive layer is preferably 1% by mass or more, more preferably 2.5% by mass or more, and further preferably 5% by mass or more from the viewpoint of adhesiveness. Moreover, from a viewpoint of transparency and cost, it is preferable that it is 50 mass% or less, It is more preferable that it is 40 mass% or less, It is further more preferable that it is 30 mass% or less. In addition, the range of the content of (B-1) in the present invention is preferably 1 to 50% by mass, more preferably 2.5 to 40% by mass, and 5 to 30% by mass in the adhesive layer. % Is more preferable.
The type of (B-1) is not particularly limited, but from the viewpoint of flexibility and compatibility, at least a monomer unit derived from ethylene and a monomer unit derived from one or more ethylenically unsaturated silane compounds. It is preferable to contain a silane-modified polyethylene resin as a main component, which is a copolymer to be contained. Examples of the ethylenically unsaturated silane compound include vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tripropoxy silane, vinyl triisopropoxy silane, vinyl tributoxy silane, vinyl tripentyloxy silane, vinyl triphenoxy silane, vinyl tri Examples include benzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane.
The method for producing the silane-modified polyethylene resin is not particularly limited, but it can be obtained by melt-mixing a polyethylene resin, an ethylenically unsaturated silane compound and a radical generator at a high temperature and graft polymerization. In addition, the content of the monomer unit derived from the ethylenically unsaturated silane compound in the silane-modified polyethylene resin used in the present invention is not particularly limited, but in order to improve the adhesion, When the total monomer unit constituting the modified polyethylene resin is 100% by mass, it is preferably 0.05% by mass or more, more preferably 0.5% by mass or more, and 1.0% by mass. It is still more preferable that it is above. Moreover, it is preferable that it is 40 mass% or less from viewpoints, such as blocking prevention of a raw material pellet, It is more preferable that it is 30 mass% or less, It is further more preferable that it is 20 mass% or less. In addition, the amount of the ethylenically unsaturated silane compound in (B-1) used in the present invention is preferably 0.05 to 40% by mass, more preferably 0.5 to 30% by mass, More preferably, it is 1.0-20 mass%. The kind and content of various monomer units constituting the silane-modified polyethylene resin can be analyzed by a well-known method, for example, an NMR measurement apparatus or other instrumental analysis apparatus. (B-1) used for this invention may be used individually by 1 type, and may mix and use 2 or more types.

  In addition, the silane modified polyethylene resin used for this invention may contain other monomer units other than the monomer unit derived from ethylene and an ethylenically unsaturated silane compound. Examples of the other monomer include an α-olefin having 3 to 30 carbon atoms, an acrylic ester, a cyclic olefin, a vinyl aromatic compound (such as styrene), and a polyene compound. The content of other monomer units is preferably 20% by mass or less, and preferably 15% by mass or less, based on 100% by mass of all monomer units constituting the silane-modified polyethylene resin. More preferred. Further, the silane-modified polyethylene resin used in the present invention will be described later as other monomer units as long as it is less than the content (% by mass) of monomer units derived from the ethylenically unsaturated silane compound (B -2) The monomer unit derived from an epoxy group-containing olefin as used in 2) may be contained.

  The weight average molecular weight of the silane-modified polyethylene resin used in the present invention is preferably 8,000 or more, more preferably 10,000 or more, and still more preferably 100,000 or more. If it is this range, it can suppress that a silane modified polyethylene resin bleeds out from a sealing material, and is preferable. The upper limit of the weight average molecular weight is not particularly limited, but is usually about 300,000.

  Specific examples of the silane-modified polyethylene resin used in the present invention include trade name “LINKLON” manufactured by Mitsubishi Chemical Corporation.

  The silane-modified polyethylene resin used in the present invention includes (B-1-1) a silane-modified polyethylene resin having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry, and (B-1 -2) Any of silane-modified polyethylene resins having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry, (B-1-1) and (B-1-2) However, from the viewpoint of improving the heat resistance of the sealing material, it is preferable to contain (B-1-2). In particular, when the adhesive layer of the sealing material of the present invention does not contain (B-2-2) or (C) described later, it is preferable to contain (B-1-2).

  The content of the silane-modified polyethylene resin in the present invention (when both (B-1-1) and (B-1-2) are used, the total amount thereof) is in the adhesive layer from the viewpoint of adhesiveness. 1 mass% or more is preferable, 2.5 mass% or more is more preferable, and 5 mass% or more is further more preferable. Moreover, from a viewpoint of transparency and cost, it is preferable that it is 50 mass% or less, It is more preferable that it is 40 mass% or less, It is further more preferable that it is 30 mass% or less. The range of the content of the silane-modified polyethylene resin in the present invention (the total amount when both (B-1-1) and (B-1-2) are used) is 1 in the adhesive layer. It is preferable that it is -50 mass%, It is more preferable that it is 2.5-40 mass%, It is further more preferable that it is 5-30 mass%.

(B-1-1) Silane-modified polyethylene resin having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry In the differential scanning calorimetry of (B-1-1) used in the present invention. The melting point measured at a heating rate of 10 ° C./min is not particularly limited as long as it is less than 90 ° C., but is preferably 85 ° C. or less, more preferably 80 ° C. or less from the viewpoint of improving transparency and flexibility. More preferably it is. Moreover, it is preferable that it is 40 degreeC or more from viewpoints, such as blocking prevention of a sealing material, It is more preferable that it is 45 degreeC or more, It is further more preferable that it is 50 degreeC or more. In addition, the range of the melting point measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (B-1-1) used in the present invention is preferably 45 ° C. to 85 ° C., more preferably 50 ° C. to 80 ° C. preferable.

  In addition, the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (B-1-1) used in the present invention is 5 J / g or more from the viewpoint of preventing blocking of the sealing material. Is preferably 10 J / g or more, and more preferably 20 J / g or more. Further, from the viewpoint of improving transparency and flexibility, it is preferably 90 J / g or less, more preferably 80 J / g or less, and further preferably 70 J / g or less. The range of the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (B-1-1) used in the present invention is preferably 5 to 90 J / g, 80 J / g is more preferable, and 20 to 70 J / g is even more preferable.

(B-1-2) Silane-modified polyethylene resin having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry In the differential scanning calorimetry of (B-1-2) used in the present invention. The melting point measured at a heating rate of 10 ° C./min is not particularly limited as long as it is 90 ° C. or higher, but is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, from the viewpoint of heat resistance. Moreover, from a viewpoint of a softness | flexibility or transparency, it is preferable that it is 160 degrees C or less, It is more preferable that it is 150 degrees C or less, It is further more preferable that it is 140 degrees C or less. In addition, as for the range of melting | fusing point measured by the heating rate of 10 degree-C / min in the differential scanning calorimetry of (B-1-2) used for this invention, 100 to 150 degreeC is more preferable, and 110 to 140 degreeC is more preferable. Further preferred.

In addition, the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (B-1-2) used in the present invention is preferably 90 J / g or more from the viewpoint of heat resistance. 100 J / g or more, more preferably 105 J / g or more. Moreover, from a viewpoint of making transparency and a softness | flexibility favorable, it is preferable that it is 160 J / g or less, It is more preferable that it is 150 J / g or less, It is further more preferable that it is 140 J / g or less. In addition, it is preferable that the range of the calorie | melting calorie | heat amount measured by the heating rate of 10 degree-C / min in the differential scanning calorimetry of (B-1-2) used for this invention is 90-160 J / g, 100- 150 J / g is more preferable, and 105 to 140 J / g is even more preferable.
Further, from the viewpoint of securing higher heat resistance, the crystal melting heat amount (ΔH _{≧ 90 ° C.} ) of _{90 ° C.} or more is preferably 10 J / g or more, more preferably 20 J / g or more, and further preferably 30 J / g or more. Further, from the viewpoint of transparency, ΔH _{≧ 90 ° C.} is preferably 130 J / g or less, more preferably 110 J / g or less, and even more preferably 100 J / g or less. In addition, the range of 90 ° C. or higher crystal melting calorie (ΔH _{≧ 90 ° C.} ) in the differential scanning calorimetry (B-1-2) used in the present invention is preferably 10 to 130 J / g. 110 J / g is more preferable, and 30 to 100 J / g is even more preferable.
Further, the heat of crystal melting at 120 ° C. or higher (ΔH _{≧ 120 ° C.} ) is preferably 5 J / g or higher, more preferably 10 J / g or higher, and further preferably 15 J / g or higher. From the viewpoint of transparency, ΔH _{≧ 120 ° C.} is preferably 100 J / g or less, more preferably 50 J / g or less, and further preferably 45 J / g or less. In addition, it is preferable that the range of ₁₂₀ degreeC or more crystal fusion calorie | heat amount ((DELTA) H _{> = 120} degreeC) in the differential scanning calorimetry of (B-1-2) used for this invention is 5-100 J / g, More preferably, it is 50 J / g, and it is further more preferable that it is 15-45 J / g.
In addition, calorie | heat amount of crystal melting more than a certain temperature (90 degreeC or 120 degreeC) can be measured by the method described in an Example.

(B-2) Epoxy-modified polyolefin resin

(B-2) used in the present invention is a polyolefin resin containing a plurality of epoxy groups in the molecule. In the present invention, the content of (B-2) in the adhesive layer is preferably 1% by mass or more, more preferably 2.5% by mass or more, and further preferably 5% by mass or more from the viewpoint of adhesiveness. Moreover, from a viewpoint of transparency and cost, it is preferable that it is 50 mass% or less, It is more preferable that it is 40 mass% or less, It is further more preferable that it is 30 mass% or less. Moreover, the range of the content of (B-2) in the present invention is preferably 1 to 50% by mass, more preferably 2.5 to 40% by mass, and 5 to 30% by mass in the adhesive layer. % Is more preferable.
Although the kind of (B-2) used for this invention is not specifically limited, From a softness | flexibility and a compatible viewpoint, at least the monomer unit derived from ethylene and the single quantity derived from 1 or more types of epoxy group containing olefins It is preferable to contain an epoxy-modified polyethylene resin, which is a copolymer containing body units, as a main component. Examples of the epoxy group-containing olefin include glycidyl acrylate, glycidyl methacrylate, and glycidyl itaconate. Although the manufacturing method of an epoxy-modified polyethylene resin is not specifically limited, For example, it can manufacture by copolymerizing an epoxy group containing olefin with ethylene. In addition, the content of the monomer unit derived from the epoxy group-containing olefin in the epoxy-modified polyethylene resin used in the present invention is not particularly limited, but in order to improve the adhesion, the epoxy-modified polyethylene When the total monomer unit constituting the resin is 100% by mass, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, and 1.2% by mass or more. Further preferred. Moreover, it is preferable that it is 40 mass% or less from viewpoints, such as blocking prevention of a raw material pellet, It is more preferable that it is 30 mass% or less, It is further more preferable that it is 20 mass% or less. In addition, it is preferable that it is 0.5-40 mass%, and content of the monomer unit derived from the poxy group containing olefin in (B-2) used for this invention is 1-30 mass%. Is more preferable, and it is still more preferable that it is 1.2-20 mass%. The kind and content of various monomer units of the epoxy-modified polyethylene resin can be analyzed by a well-known method, for example, an NMR measurement apparatus or other instrumental analysis apparatus. (B-2) used for this invention may be used individually by 1 type, and may mix and use 2 or more types.

  The monomer unit constituting the epoxy-modified polyethylene resin used in the present invention may contain other monomer units other than monomer units derived from ethylene and epoxy group-containing olefin. Examples of the other monomer include an α-olefin having 3 to 30 carbon atoms, an acrylic ester, a cyclic olefin, a vinyl aromatic compound (such as styrene), and a polyene compound. The content of other monomer units is preferably 20% by mass or less, more preferably 15% by mass or less, based on 100% by mass of the total monomer units of the epoxy-modified polyethylene resin. . Further, the epoxy-modified polyethylene resin used in the present invention is the above-described other monomer unit (B-1) as long as it is less than the content (% by mass) of the monomer unit derived from the epoxy group-containing olefin. It may contain a monomer unit derived from an ethylenically unsaturated silane compound as used in the above.

  The weight average molecular weight of the epoxy-modified polyethylene resin used in the present invention is preferably 8,000 or more, more preferably 10,000 or more, and still more preferably 100,000 or more. If it is this range, it can suppress that an epoxy-modified polyethylene-type resin bleeds out from a sealing material, and is preferable. The upper limit of the weight average molecular weight is not particularly limited, but is usually about 300,000.

  Specific examples of the epoxy-modified polyethylene resin used in the present invention include the trade name “BONDAST 7B” manufactured by Sumitomo Chemical Co., Ltd., the trade name “BONDAST E”, and the trade name “Arkema” LOTADA GMA "etc. are mentioned.

  The epoxy-modified polyethylene resin used in the present invention includes (B-2-1) an epoxy-modified polyethylene resin having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry, and (B-2 -2) Any of epoxy-modified polyethylene resins having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry, (B-2-1) and (B-2-2) However, it is preferable to contain (B-2-2) from the viewpoint of improving the heat resistance of the sealing material. In particular, when the adhesive layer of the sealing material of the present invention does not contain the above-described (B-1-2) or (C) described later, it is preferable to contain (B-2-2).

  The content of the epoxy-modified polyethylene resin in the present invention (when both (B-2-1) and (B-2-2) are used, the total amount thereof) is in the adhesive layer from the viewpoint of adhesiveness. 1 mass% or more is preferable, 2.5 mass% or more is more preferable, and 5 mass% or more is further more preferable. Moreover, from a viewpoint of transparency and cost, it is preferable that it is 50 mass% or less, It is more preferable that it is 40 mass% or less, It is further more preferable that it is 30 mass% or less. The range of the content of the epoxy-modified polyethylene resin in the present invention (the total amount when both (B-2-1) and (B-2-2) are used) is 1 in the adhesive layer. It is preferable that it is -50 mass%, It is more preferable that it is 2.5-40 mass%, It is further more preferable that it is 5-30 mass%.

(B-2-1) Epoxy-modified polyethylene resin having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry In the differential scanning calorimetry of (B-2-1) used in the present invention. The melting point measured at a heating rate of 10 ° C./min is not particularly limited as long as it is less than 90 ° C., but is preferably 85 ° C. or less, more preferably 80 ° C. or less from the viewpoint of improving transparency and flexibility. More preferably it is. Moreover, it is preferable that it is 40 degreeC or more from viewpoints, such as blocking prevention of a sealing material, It is more preferable that it is 45 degreeC or more, It is further more preferable that it is 50 degreeC or more. In addition, 45-85 degreeC is preferable and, as for the range of melting | fusing point measured by the heating rate of 10 degree-C / min in the differential scanning calorimetry of (B-2-1) used for this invention, 50-80 degreeC is more preferable.

  In addition, the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of (B-2-1) used in the present invention is 5 J / g or more from the viewpoint of preventing blocking of the sealing material. Is preferably 10 J / g or more, and more preferably 20 J / g or more. Further, from the viewpoint of improving transparency and flexibility, it is preferably 90 J / g or less, more preferably 80 J / g or less, and further preferably 70 J / g or less. The range of the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (B-2-1) used in the present invention is preferably 5 to 90 J / g, 80 J / g is more preferable, and 20 to 70 J / g is even more preferable.

(B-2-2) Epoxy-modified polyethylene resin having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry In the differential scanning calorimetry of (B-2-2) used in the present invention. The melting point measured at a heating rate of 10 ° C./min is not particularly limited as long as it is 90 ° C. or higher, but is preferably 100 ° C. or higher, more preferably 105 ° C. or higher from the viewpoint of heat resistance. Moreover, from a viewpoint of a softness | flexibility or transparency, it is preferable that it is 160 degrees C or less, It is more preferable that it is 150 degrees C or less, It is further more preferable that it is 140 degrees C or less. In addition, the range of the melting point measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (B-2-2) used in the present invention is more preferably 100 ° C. to 150 ° C., and 105 ° C. to 140 ° C. Further preferred.

Further, the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of (B-2-2) used in the present invention is preferably 90 J / g or more from the viewpoint of heat resistance, More preferably, it is 100 J / g or more, and further preferably 105 J / g or more. Moreover, from a viewpoint of making transparency and a softness | flexibility favorable, it is preferable that it is 160 J / g or less, It is more preferable that it is 150 J / g or less, It is further more preferable that it is 140 J / g or less.
The range of the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (B-2-2) used in the present invention is preferably 90 to 160 J / g, preferably 100 to 150 J / g is more preferable, and 105 to 140 J / g is even more preferable.
Further, from the viewpoint of securing higher heat resistance, the crystal melting heat amount (ΔH _{≧ 90 ° C.} ) of _{90 ° C.} or more is preferably 10 J / g or more, more preferably 20 J / g or more, and further preferably 30 J / g or more. Further, from the viewpoint of transparency, ΔH _{≧ 90 ° C.} is preferably 130 J / g or less, more preferably 110 J / g or less, and even more preferably 100 J / g or less. In the differential scanning calorimetry (B-2-2) used in the present invention, the range of 90 ° C. or higher crystal melting calorie (ΔH _{≧ 90 ° C.} ) is preferably 10 to 130 J / g. 110 J / g is more preferable, and 30 to 100 J / g is even more preferable.
Further, the heat of crystal melting at 120 ° C. or higher (ΔH _{≧ 120 ° C.} ) is preferably 5 J / g or higher, more preferably 10 J / g or higher, and further preferably 15 J / g or higher. From the viewpoint of transparency, ΔH _{≧ 120 ° C.} is preferably 100 J / g or less, more preferably 50 J / g or less, and further preferably 45 J / g or less. The heat of crystal melting above a certain temperature (90 ° C. or 120 ° C.) can be measured by the method described in the examples. In the differential scanning calorimetry (B-2-2) used in the present invention, the range of 120 ° C. or higher crystal melting calorie (ΔH _{≧ 120 ° C.} ) is preferably 5 to 100 J / g, More preferably, it is 50 J / g, and it is further more preferable that it is 15-45 J / g.
The content of (A), (B-1) and (B-2) in the adhesive layer of the solar cell encapsulant of the present invention is (A) 40 to 98 in the adhesive layer from the viewpoint of adhesiveness and cost. It is preferable that they are 1 mass%, (B-1) 1-50 mass%, and (B-2) 1-50 mass%, (A) 50-95 mass%, (B-1) 2.5-40 mass. % And (B-2) 2.5 to 40% by mass, (A) 60 to 90% by mass, (B-1) 5 to 30% by mass and (B-2) 5 to 30% by mass. % Is more preferable.

  Further, the adhesive layer of the solar cell encapsulant of the present invention is a polyolefin resin having a melting point of 90 ° C. or higher, which is further measured at a heating rate of 10 ° C./min in differential scanning calorimetry, in order to easily satisfy the condition (i) (C) may be contained. Note that (C) does not include a silane-modified polyolefin resin or an epoxy-modified polyolefin resin.

(C) Polyolefin resin having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry (C) is measured at a heating rate of 10 ° C./min in differential scanning calorimetry. The melting point is not particularly limited as long as it has a melting point of 90 ° C. or higher and is not modified with silane or epoxy. Examples thereof include low density polyethylene, ethylene / α-olefin copolymer, medium density polyethylene, and high density polyethylene. Of these, (C-1) an ethylene / α-olefin block copolymer and (C-2) an ethylene / α-olefin random copolymer are preferably used from the viewpoint of easily achieving both flexibility and heat resistance. . The melting point measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of (C-1) ethylene / α-olefin block copolymer and (C-2) ethylene / α-olefin random copolymer is: From the viewpoint of heat resistance, the temperature is more preferably 100 ° C. or higher, and further preferably 110 ° C. or higher. Moreover, from a viewpoint of a softness | flexibility or transparency, it is preferable that it is 160 degrees C or less, It is more preferable that it is 150 degrees C or less, It is further more preferable that it is 140 degrees C or less. In addition, the range of the melting point measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of (C-1) and (C-2) used in the present invention is more preferably 100 ° C. to 150 ° C., and 110 ° C. ˜140 ° C. is more preferable.
Here, when placing the highest importance on the transparency of the solar cell encapsulant, it is preferable to use (C-1) an ethylene / α-olefin block copolymer, and when placing the highest importance on cost (C- 2) It is preferable to use an ethylene / α-olefin random copolymer. In addition, (C) used for this invention may be used individually by 1 type, and may be used in mixture of 2 or more types.
The content of (C) in the present invention is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and further preferably 0 to 10% by mass in the adhesive layer from the viewpoint of achieving both heat resistance and transparency. preferable.

(C-1) Ethylene / α-Olefin Block Copolymer In (C-1) used in the present invention, the α-olefin copolymerized with ethylene usually has 3 to 20 carbon atoms. Used, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 3-methyl-butene-1, 4-methyl-pentene -1 etc. are mentioned. Among these, 1-butene, 1-hexene and 1-octene are preferred from the viewpoints of industrial availability, various characteristics (flexibility, heat resistance, transparency, impact resistance), economic efficiency, and the like. Is preferred. α-olefins may be used alone or in combination of two or more.
Such an ethylene / α-olefin block copolymer is mixed with an amorphous soft segment and a highly crystalline hard segment, thereby increasing the melting point and improving the heat resistance while improving flexibility. It is preferable in that it can be given.

  The content of the monomer unit derived from α-olefin in (C-1) used in the present invention is not particularly limited as long as it can ensure that the melting point of (C-1) is 90 ° C. or higher. However, when the total monomer unit constituting the ethylene / α-olefin copolymer is 100% by mass, it is usually 1 to 50% by mass, preferably 5 to 45% by mass, more preferably 10 to 40% by mass. is there. If the content of the α-olefin-derived monomer unit is 1% by mass or more, flexibility can be imparted. Moreover, if content of the monomer unit derived from (alpha) -olefin is 50 mass% or less, heat resistance can be ensured.

  In addition, (C-1) used in the present invention is a single amount derived from ethylene and α-olefin, as long as the melting point measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 90 ° C. or more. Other monomer units other than the body unit may be contained. Examples of other monomers include acrylic acid esters, cyclic olefins, vinyl aromatic compounds (such as styrene), and polyene compounds. The content of other monomer units is preferably 20% by mass or less, and preferably 15% by mass or less, based on 100% by mass of all monomer units constituting (C-1). More preferred.

  The block structure (C-1) used in the present invention has various physical properties (comonomer content, crystallinity, density, melting point, glass transition temperature, etc.) from the viewpoint of balance of flexibility, heat resistance, transparency, and the like. A multi-block structure having two or more, preferably three or more segments or blocks having at least one of the physical properties is preferred. Specific examples include a completely symmetric block, an asymmetric block, and a tapered block structure (a structure in which the ratio of the block structure gradually increases in the main chain). The structure and production method of the copolymer having a multi-block structure are disclosed in detail in International Publication No. 2005/090425, International Publication No. 2005/090426, International Publication No. 2005/090427, etc. Can be adopted.

  As the ethylene / α-olefin block copolymer (C-1) having a multi-block structure, a substantially amorphous soft segment obtained by copolymerizing a large amount of α-olefin with respect to ethylene, and α- with respect to ethylene. A multi-block copolymer in which two or more highly crystalline hard segments having a high melting point and copolymerized with less olefin are present is preferable. By controlling the chain length and ratio of these soft segments and hard segments, both flexibility and heat resistance can be achieved. The ethylene / α-olefin block copolymer (C-1) having a multi-block structure can more easily achieve both flexibility and heat resistance when 1-octene is used as the α-olefin.

The heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of (C-1) used in the present invention is preferably 5 J / g or more from the viewpoint of heat resistance. More preferably, it is more preferably 30 J / g or more. Further, from the viewpoint of improving transparency and flexibility, it is preferably 100 J / g or less, more preferably 90 J / g or less, and further preferably 70 J / g or less. In addition, the range of the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (C-1) used in the present invention is preferably 5 to 100 J / g, and 10 to 90 J / g. It is more preferable that it is g, and it is still more preferable that it is 30-70 J / g.
Further, from the viewpoint of securing higher heat resistance, the crystal melting heat amount (ΔH _{≧ 90 ° C.} ) of _{90 ° C.} or more is preferably 10 J / g or more, more preferably 20 J / g or more, and further preferably 30 J / g or more. From the viewpoint of transparency, ΔH _{≧ 90 ° C.} is preferably ₉₀ J / g or less, more preferably 80 J / g or less, and further preferably 60 J / g or less. The range of the heat of crystal fusion (ΔH _{≧ 90 ° C.} ) of _{90 °} C. or higher of (C-1) used in the present invention is preferably 10 to 90 J / g, and preferably 20 to 80 J / g. More preferably, it is 30-60 J / g.
Further, the heat of crystal melting at 120 ° C. or higher (ΔH _{≧ 120 ° C.} ) is preferably 5 J / g or higher, more preferably 10 J / g or higher, and further preferably 15 J / g or higher. Further, from the viewpoint of transparency, ΔH _{≧ 120 ° C.} is preferably 80 J / g or less, more preferably 50 J / g or less, and further preferably 45 J / g or less. In addition, it is preferable that the range of the crystal melting calorie | heat amount ((DELTA) H _{> = 120} degreeC) of ₁₂₀ degreeC or more of (C-1) used for this invention is 5-80 J / g, and it is 10-50 J / g. More preferably, it is 15-45 J / g.

  The melt flow rate (temperature 190 ° C., load 21.18 N) according to JIS K7210 of (C-1) used in the present invention is 0.1 to 10 g from the viewpoint of film forming properties and heat resistance of the sealing material. / 10 min is preferable, and 0.5 to 5.0 g / 10 min is more preferable.

Density of use in the present invention (C-1), from the viewpoint of heat resistance, is preferably 0.865 g / cm ³ or more, more preferably 0.870 g / cm ³ or more, 0.874 g / Cm ³ or more is more preferable. From the viewpoint of transparency, preferably less than 0.900 g / cm ^3, more preferably less than 0.895 g / cm ^3, more preferably less than 0.891 g / cm ^3. The range of the density of the used in the present invention (C-1), is preferably less than 0.865 g / cm ³ or more ^{0.900g / cm 3, 0.870g / cm} 3 or more 0.895 g / cm preferably less than ^3, more preferably less than 0.874 g / cm ³ or more 0.891 g / cm ^3.

  Specific examples of (C-1) used in the present invention include trade name “Infuse” manufactured by Dow Chemical Company.

(C-2) Ethylene / α-Olefin Random Copolymer In (C-2) used in the present invention, the α-olefin copolymerized with ethylene usually has 3 to 20 carbon atoms. Used, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 3-methyl-butene-1, 4-methyl-pentene -1 etc. are mentioned. Among these, 1-butene, 1-hexene, or 1-octene is preferable from the viewpoint of industrial availability, economy, and the like. As the α-olefin copolymerized with ethylene, only one kind may be used alone, or two or more kinds may be used in combination at any ratio.

  In (C-2) used in the present invention, the content of the monomer unit derived from α-olefin copolymerized with ethylene is 10 heating rate in differential scanning calorimetry of ethylene / α-olefin random copolymer. If it can ensure that melting | fusing point measured in deg. C / min is 90 degree C or more, it will not specifically limit, When all the monomer units which comprise an ethylene / alpha-olefin random copolymer are 100 mass% 1 to 20% by mass, more preferably 2 to 15% by mass, and even more preferably 3 to 10% by mass. Within this range, the melting point is high, and heat resistance is easily secured, which is preferable.

  (C-2) used in the present invention is a monomer unit derived from ethylene and α-olefin, as long as the melting point measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 90 ° C. or higher. Other monomer units other than may be contained. Examples of other monomers include acrylic acid esters, cyclic olefins, vinyl aromatic compounds (such as styrene), and polyene compounds. The content of other monomers is preferably 20% by mass or less, more preferably 15% by mass or less, assuming that all monomer units constituting (C-2) are 100% by mass. .

The heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (C-2) used in the present invention is preferably 90 J / g or more from the viewpoint of heat resistance, and is 100 J / g. More preferably, it is more preferably 105 J / g or more. Moreover, from a viewpoint of making transparency and a softness | flexibility favorable, it is preferable that it is 160 J / g or less, It is more preferable that it is 150 J / g or less, It is further more preferable that it is 140 J / g or less. The range of the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (C-2) used in the present invention is preferably 90 to 160 J / g, and preferably 100 to 150 J / g. g is more preferable, and 105 to 140 J / g is even more preferable.
Further, from the viewpoint of securing higher heat resistance, the crystal melting heat amount (ΔH _{≧ 90 ° C.} ) of _{90 ° C.} or more is preferably 10 J / g or more, more preferably 20 J / g or more, and further preferably 30 J / g or more. Further, from the viewpoint of transparency, ΔH _{≧ 90 ° C.} is preferably 130 J / g or less, more preferably 110 J / g or less, and even more preferably 100 J / g or less. The range of the heat of crystal fusion (ΔH _{≧ 90 ° C.} ) of _{90 °} C. or higher of (C-2) used in the present invention is preferably 10 to 130 J / g, and preferably 20 to 110 J / g. More preferably, it is 30-100 J / g.
Further, the heat of crystal melting at 120 ° C. or higher (ΔH _{≧ 120 ° C.} ) is preferably 5 J / g or higher, more preferably 10 J / g or higher, and further preferably 15 J / g or higher. From the viewpoint of transparency, ΔH _{≧ 120 ° C.} is preferably 100 J / g or less, more preferably 50 J / g or less, and further preferably 45 J / g or less. In addition, the range of the heat of crystal melting (ΔH _{≧ 120 ° C.} ) of _{120 °} C. or higher of (C-2) used in the present invention is preferably 5 to 100 J / g, and preferably 10 to 50 J / g. More preferably, it is 15-45 J / g.

  The melt flow rate (temperature 190 ° C., load 21.18 N) according to JIS K7210 of (C-2) used in the present invention is 0.1 to 10 g / 10 min from the viewpoint of film forming properties and heat resistance. It is preferably 0.5 to 5.0 g / 10 min.

Density of use in the present invention (C-2), is not particularly limited, from the viewpoint of heat resistance, is preferably 0.910 g / cm ³ or more, at 0.911 g / cm ³ or more More preferably, it is 0.912 g / cm ³ or more. From the viewpoint of flexibility, it is preferably 0.965 g / cm ³ or less, more preferably 0.940 g / cm ³ or less, and more preferably 0.925 g / cm ³ or less. The range of the density of use in the present invention (C-2), is preferably 0.910~0.965g / cm ^3, more preferably 0.911~0.940g / cm ³ 0.912 to 0.925 g / cm ³ is more preferable.

  The manufacturing method of (C-2) used for this invention is not specifically limited, The well-known polymerization method using the well-known ethylene polymerization catalyst is employable. Known polymerization methods include, for example, a slurry polymerization method, a solution polymerization method using a multisite catalyst typified by a Ziegler-Natta type catalyst, and a single site catalyst typified by a metallocene catalyst and a postmetallocene catalyst, Examples include a gas phase polymerization method, and a bulk polymerization method using a radical initiator.

  (C-2) Specific examples of the ethylene / α-olefin random copolymer include the product name “NEOZEX” manufactured by Prime Polymer Co., Ltd., the product name “Excellen VL” manufactured by Sumitomo Chemical Co., Ltd., and the product manufactured by Dow Chemical Co. The name “Athein”, the product name “Harmolex” manufactured by Nippon Polyethylene Co., Ltd., and the like.

<Adhesive layer>
The amount of heat of crystal melting measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of the adhesive layer in the solar cell encapsulant of the present invention is particularly limited if the solar cell encapsulant of the present invention satisfies the condition (i). However, from the viewpoint of improving transparency and flexibility, it is preferably 100 J / g or less, more preferably 90 J / g or less, and further preferably 80 J / g or less. In order to make the heat of crystal fusion within this range, the components having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (the aforementioned (A), (B-1-1), and ( The total content of B-2-1)) is preferably 60% by mass or more in the adhesive layer, more preferably 70% by mass or more, and further preferably 75% by mass or more. Further, from the viewpoint of handling properties and blocking suppression, the heat of crystal melting measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of the adhesive layer is preferably 10 J / g or more, more preferably 20 J / g or more. More preferably, it is more preferably 30 J / g or more. The range of the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of the adhesive layer in the solar cell encapsulant of the present invention is preferably 10 to 100 J / g, and 20 to 90 J. / G is more preferable, and 30 to 80 J / g is even more preferable.
This can be adjusted by the type and content of the components constituting the adhesive layer.

Further, from the viewpoint of ensuring a higher heat resistance, the adhesive layer in the solar cell encapsulant of the present invention, the measured 90 ° C. or more heat of crystal fusion at a heating rate of 10 ° C. / min in differential scanning calorimetry ([Delta] H _{≧ 90 ° C.} ) is preferably 1.0 J / g or more, more preferably 1.5 J / g or more, and further preferably 2.0 J / g or more. From the viewpoint of transparency and flexibility, ΔH _{≧ 90 ° C.} is preferably 30.0 J / g or less, more preferably 20.0 J / g or less, and 10.0 J / g or less. Is more preferable. In addition, it is preferable that the range of (DELTA) H _{> = 90} degreeC of the contact bonding layer in the solar cell sealing material of this invention is 1.0-30.0 J / g, and it is 1.5-20.0 J / g. More preferably, it is 2.0-10.0 J / g.
Also, from the viewpoint of higher heat resistance, the crystal melting heat quantity (ΔH _{≧ 120 ° C.} ) measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of the adhesive layer is 0.01 J / g or more. Preferably, 0.1 J / g or more is more preferable, and 0.4 J / g or more is further preferable. From the viewpoint of transparency, ΔH _{≧ 120 ° C.} is preferably 20.0 J / g or less, more preferably 10.0 J / g or less, and further preferably 5.0 J / g or less. . In addition, it is preferable that the range of (DELTA) H _{> = 120} degreeC of the contact bonding layer in the solar cell sealing material of this invention is 0.01-20.0 J / g, and it is 0.1-10.0 J / g. More preferably, it is 0.4-5.0 J / g.
ΔH _{≧ 90 ° C.} and ΔH _{≧ 120 ° C.} are components having a melting point of 90 ° C. or more measured at a heating rate of 10 ° C./min in differential scanning calorimetry (described above (B-1-2), (B-2 -2) and (C)). The total content of components having a melting point of 90 ° C. or higher is preferably 1% by mass or more, more preferably 1.5% by mass or more in the adhesive layer in order to bring the heat of crystal fusion within the above range. Preferably, it is 2 mass% or more. Further, from the viewpoint of transparency and cost, it is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less. In addition, it is preferable that it is 1-40 mass%, as for the total range of content of a component whose melting | fusing point is 90 degreeC or more, it is more preferable that it is 1.5-30 mass%, and it is 2-25 mass%. More preferably.

  The melt flow rate (temperature 190 ° C., load 21.18 N) of the adhesive layer in the solar cell encapsulant of the present invention conforming to JIS K7210 is not particularly limited, but film formability and productivity, and glass From the viewpoint of improving wettability to solar cells and the like, it is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and further preferably 2 g / 10 min or more. Further, from the viewpoint of heat resistance, it is preferably 30 g / 10 min or less, more preferably 15 g / 10 min or less, still more preferably 10 g / 10 min or less. In addition, the range of MFR of the adhesive layer in the solar cell encapsulant of the present invention is preferably 0.5 to 30 g / 10 min, more preferably 1 to 15 g / 10 min, and 2 to 10 g / 10 min. More preferably. In addition, MFR can be adjusted with MFR and content of the component which comprises an adhesive layer.

  Since the adhesive layer in the solar cell sealing material of the present invention contains a silane-modified polyolefin resin excellent in adhesion to glass and an epoxy-modified polyolefin resin excellent in adhesion to solar cells, glass and Good adhesion to both solar cells. Since the adhesive layer in the solar cell encapsulant of the present invention has low reactivity of the silane-modified polyolefin resin and the epoxy-modified polyolefin resin, it does not gel during melt-kneading with an extruder or the like to form the adhesive layer. Excellent in productivity. Here, non-gelling can be confirmed by the fact that the ratio of soluble toluene in the adhesive layer after melt-kneading and molding is less than 1% by mass.

<Solar cell encapsulant>
In the solar cell encapsulant of the present invention, (i) a crystal melting heat quantity (ΔH _{≧ 90 ° C.} ) of _{90 °} C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 1.5-30 J / g. To meet. From the viewpoint of heat resistance, the heat of crystal melting (ΔH _{≧ 90 ° C.} ) is more preferably 2.0 J / g or more, and further preferably 3.0 J / g or more. Moreover, from a viewpoint of transparency, it is more preferable that it is 20.0 J / g or less, and it is further more preferable that it is 10.0 J / g or less. In addition, it is preferable that (DELTA) H _{> = 90} degreeC of the solar cell sealing material of this invention is 2.0-20.0 J / g, and it is more preferable that it is 3.0-10.0 J / g.
The solar cell encapsulating material of the present invention may be composed of one or more adhesive layers as described above, and may be composed of only an adhesive layer, or one or more of the above-mentioned adhesive layers laminated on the outermost layer. A laminated structure with a layer other than the layer may be used. From the viewpoint of cost and productivity, it is preferable to have a laminated structure of three or more layers with the adhesive layer as both outermost layers (front and back layers).

  When the solar cell encapsulant of the present invention has a configuration in which one or more adhesive layers are laminated on the outermost layer, the layers other than the adhesive layer are measured at a heating rate of 10 ° C./min in (D) differential scanning calorimetry. The main component is preferably a resin composition comprising a polyolefin resin having a melting point of less than 90 ° C. and (E) a polyolefin resin having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry. In addition, (D) and (E) can use the thing similar to what was mentioned by (A) and (C), respectively. Here, (D) and (E) may be the same as (A) and (C) or may be different.

The amount of crystal melting heat of the layers other than the adhesive layer in the solar cell encapsulant of the present invention is not particularly limited as long as the solar cell encapsulant of the present invention satisfies the condition (i), but from the viewpoint of handling properties, The crystal melting heat quantity measured at a heating rate of 10 ° C./min in differential scanning calorimetry is preferably 10 J / g or more, more preferably 20 J / g or more, and further preferably 30 J / g or more. preferable. Further, from the viewpoint of improving transparency and flexibility, it is preferably 100 J / g or less, more preferably 90 J / g or less, and further preferably 80 J / g or less. In addition, the range of the heat of crystal melting measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of the solar cell encapsulant of the present invention is preferably 10 to 100 J / g, and 20 to 90 J / g. More preferably, it is more preferably 30 to 80 J / g.
In order to keep the heat of crystal fusion within this range, the content of the component having the melting point of less than 90 ° C. (described above (D)) measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 60 in this layer. It is preferably at least mass%, more preferably at least 70 mass%, and even more preferably at least 75 mass%.
This can be adjusted by the type and content of the components constituting this layer.

Further, from the viewpoint of heat resistance, it is preferable that the heat of crystal fusion (ΔH _{≧ 90 ° C.} ) of 90 ° C. or higher of the layers other than the adhesive layer of the solar cell sealing material of the present invention is 1.5 J / g or more, 2.0 J / g or more is more preferable, and 3.0 J / g or more is more preferable. From the viewpoint of transparency and flexibility, ΔH _{≧ 90 ° C.} is preferably 30.0 J / g or less, more preferably 20.0 J / g or less, and 10.0 J / g or less. Is more preferable. The range of ΔH _{≧ 90 ° C.} of this layer is preferably 1.5 to 30.0 J / g, more preferably 2 to 20.0 J / g, and 3 to 10.0 J / g. More preferably it is.
Further, from the viewpoint of higher heat resistance, the crystal melting heat quantity (ΔH _{≧ 120 ° C.} ) measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of this layer is 0.01 J / g or more. Preferably, 0.1 J / g or more is more preferable, and 0.4 J / g or more is further preferable. From the viewpoint of transparency, ΔH _{≧ 120 ° C.} is preferably 20.0 J / g or less, more preferably 10.0 J / g or less, and further preferably 5.0 J / g or less. . The range of ΔH _{≧ 120 ° C.} of this layer is preferably 0.01 to 20.0 J / g, more preferably 0.1 to 10.0 J / g, and 0.4 to 5. More preferably, it is 0 J / g.
ΔH _{≧ 90 ° C.} and ΔH _{≧ 120 ° C.} can be adjusted by the type and content of the component having the melting point of 90 ° C. or more ((E) described above) measured at a heating rate of 10 ° C./min in differential scanning calorimetry. . The total content of components having a melting point of 90 ° C. or higher is preferably 1% by mass or more, and 1.5% by mass or more in this layer in order to bring the heat of crystal fusion within the above range. Is more preferable, and it is further more preferable that it is 2 mass% or more. Further, from the viewpoint of transparency and cost, it is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less. In addition, it is preferable that it is 1-40 mass% in this layer, and, as for the total range of content of a component whose melting | fusing point is 90 degreeC or more, it is more preferable that it is 1.5-30 mass%, 2-25 More preferably, it is mass%.

  If the solar cell encapsulant of the present invention satisfies the condition (i), various physical properties (flexibility, heat resistance, transparency, adhesiveness, etc.), molding processability, economical efficiency and the like are further improved. Resins other than those described above can be included. Examples of the resin other than those described above include tackifying resins, various elastomers (such as styrene), and the like.

Examples of tackifying resins include petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and hydrogenated derivatives thereof. Specifically, the petroleum resin includes cyclopentadiene or an alicyclic petroleum resin from its dimer, and an aromatic petroleum resin from the C9 component. Examples of terpene resins include terpene resins from β-pinene and terpene-phenol resins. Examples of the coumarone-indene resin include a coumarone-indene copolymer and a coumarone-indene-styrene copolymer. Examples of the rosin resin include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin, pentaerythritol, and the like.
In addition, the tackifying resin can be obtained mainly with various softening temperatures depending on the molecular weight. From the viewpoints of compatibility when mixed with the above-mentioned polyolefin-based resin, bleed over time, color tone or thermal stability. Therefore, it is preferable to use a hydrogenated derivative of an alicyclic petroleum resin having a softening temperature of 100 to 150 ° C. The softening temperature is more preferably 120 to 140 ° C. The content of the tackifying resin is preferably 20% by mass or less, and more preferably 10% by mass or less, based on the total amount of all resins constituting each layer of the sealing material.

  Examples of the elastomer include styrene elastomer, polyester elastomer, polyamide elastomer and the like. Of these, styrene-based elastomers are preferred from the viewpoint of transparency and hydrolysis resistance. Examples of the styrene-based elastomer include SEBS (Styrene-Ethylene-Butylene-Styrene), SEBC (Styrene-Ethylene-Butylene-Crystalline Block Copolymer), HSBR (hydrogenated styrene butadiene rubber), and the like. The content of the elastomer is not particularly limited, but the content of the elastomer is preferably 20% by mass or less of the total amount of all resins constituting each layer of the sealing material from the viewpoint of weather resistance. More preferably, it is 10 mass% or less.

  Each layer of the solar cell encapsulant of the present invention can contain various additives as necessary. Examples of the additive include an antioxidant, an ultraviolet absorber, a weather resistance stabilizer, a light diffusing agent, a nucleating agent, a pigment (for example, a white pigment), a flame retardant, a discoloration preventing agent, and a wavelength converting agent. In the present invention, it is preferable to contain at least one additive selected from an antioxidant, an ultraviolet absorber, and a weathering stabilizer for reasons described later. Moreover, it is preferable that each layer of the solar cell sealing material of this invention does not contain crosslinking agents, such as an organic peroxide, from a viewpoint of productivity. Substantially not containing means 0.1% by mass or less in each layer of the sealing material, preferably 0.01% by mass or less, more preferably 0% by mass. The solar cell encapsulant of the present invention is excellent in adhesiveness, heat resistance, and transparency without containing a crosslinking agent.

The antioxidant is not particularly limited, and various commercially available products can be used. As the antioxidant, various types such as phenol, sulfur, phosphite and the like such as monophenol, bisphenol and polymer phenol can be used.
Monophenol antioxidants include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, octadecyl-3- (3 , 5-di-tert-butyl-4-hydroxyphenyl) propionate.
Examples of the bisphenol antioxidant include 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidene-bis- (3-methyl-6-tert-butylphenol), 3,9-bis [{1,1 -Dimethyl-2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl} 2,4,9,10-tetraoxaspiro] 5,5-undecane and the like. .
Polymeric phenolic antioxidants include 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6 -Tris (3,5-di-tert-butyl-4-bidoxybenzyl) benzene, tetrakis- {methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate} Methane, bis {(3,3′-bis-4′-hydroxy-3′-tert-butylphenyl) butyric acid} glycol ester, 1,3,5-tris (3 ′, 5′-di-tert -Butyl-4'-hydroxybenzyl) -s-triazine-2,4,6- (1H, 3H, 5H) trione, tocopherol (vitamin E) and the like.
Examples of the sulfur-based antioxidant include dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiopropionate.
Phosphite antioxidants include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phos Phyto, cyclic neopentanetetrayl bis (octadecyl phosphite), tris (mono and / or dinonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite 9,10-dihydro-9-oxa-10-phosphaphenalene-10-oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa -10-phosphaphenanthrene-1 0-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic Neopentanetetraylbis (2,6-di-tert-butylphenyl) phosphite, 2,2-methylenebis (4,6-tert-butylphenyl) octyl phosphite and the like can be mentioned.

  Among the above-mentioned antioxidants, phenolic and phosphite antioxidants are preferable from the viewpoint of antioxidant performance, thermal stability, economy, and the like. It is preferable at the point which can make prevention property favorable.

  The content of the antioxidant is preferably 0.1 to 1.0% by mass and more preferably 0.2 to 0.5% by mass in each layer of the sealing material.

  Various types of commercially available products can be used as the ultraviolet absorber, and various types such as benzophenone-based, benzotriazole-based, triazine-based, and salicylic acid ester-based materials can be used.

  Examples of the benzophenone ultraviolet absorber include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n-dodecyl. Oxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2,4 -Dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone and the like.

  The benzotriazole-based ultraviolet absorber is a hydroxyphenyl-substituted benzotriazole compound, for example, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-butylphenyl) Benzotriazole, 2- (2-hydroxy-3,5-dimethylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) -2H-benzotriazole, 2- (2-methyl-4-hydroxy Phenyl) benzotriazole, 2- (2-hydroxy-3-methyl-5-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole, 2- ( 2-hydroxy-3,5-di-tert-butyl Eniru) benzotriazole.

  Examples of the triazine ultraviolet absorber include 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, 2- (4 , 6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol and the like.

  Examples of salicylic acid ester ultraviolet absorbers include phenyl salicylate and p-octylphenyl salicylate.

  Although content of a ultraviolet absorber is not limited, It is preferable that it is 0.01-2.00 mass% in each layer of a sealing material, and it is 0.05-0.50 mass%. Is more preferable.

  As the weather stabilizer, a hindered amine light stabilizer is preferably used. The hindered amine light stabilizer does not absorb ultraviolet rays like the ultraviolet absorber, but has a remarkable synergistic effect when used in combination with the ultraviolet absorber.

  Examples of hindered amine light stabilizers include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly [{6- (1,1 , 3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {{2, 2,6,6-tetramethyl-4-piperidyl} imino}], N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2, 6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6,6-tetramethyl-4-piperidyl) separate, 2- (3 , 5-Di-tert-4- Mud alkoxybenzylacetic) -2-n-butyl malonic acid bis (1,2,2,6,6-pentamethyl-4-piperidyl) and the like.

  The content of the hindered amine light stabilizer is preferably 0.01 to 0.50% by mass and more preferably 0.05 to 0.30% by mass in each layer of the sealing material.

  Said antioxidant, ultraviolet absorber and weathering stabilizer may be used alone or in combination of two or more.

  Since the solar cell encapsulant of the present invention satisfies the condition (i), the solar cell encapsulant is excellent in transparency, and even when the solar cell module is heated to about 85 to 90 ° C. due to heat generated during power generation or radiant heat of sunlight. It does not flow easily and has excellent heat resistance.

Further, the crystal melting heat quantity (ΔH _{≧ 120 ° C.} ) measured at a heating rate of 10 ° C./min in differential scanning calorimetry is preferably 0.01 J / g or more, more preferably 0.1 J / g or more, 0.4 J / g or more is more preferable. From the viewpoint of transparency, ΔH _{≧ 120 ° C.} is preferably 20.0 J / g or less, more preferably 10.0 J / g or less, and further preferably 5.0 J / g or less. . The range of ΔH _{≧ 120 ° C.} of the solar cell encapsulant of the present invention is preferably 0.01 to 20.0 J / g, more preferably 0.1 to 10.0 J / g, More preferably, it is 0.4-5.0 J / g.
ΔH _{≧ 90 ° C.} and ΔH _{≧ 120 ° C.} are components having a melting point of 90 ° C. or more measured at a heating rate of 10 ° C./min in differential scanning calorimetry (described above (B-1-2), (B-2 -2), (C), (E)) can be adjusted according to the type and content. The total content of components having a melting point of 90 ° C. or higher is preferably 1% by mass or more and more preferably 2% by mass or more in the sealing material in order to bring the heat of crystal fusion within the above range. More preferably, it is 3 mass% or more. Further, from the viewpoint of transparency and cost, it is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less. In addition, it is preferable that it is 1-40 mass% in a sealing material, as for the total range of content of a component whose melting | fusing point is 90 degreeC or more, It is more preferable that it is 2-30 mass%, 3-25 mass % Is more preferable.

The heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of the solar cell encapsulant of the present invention is not particularly limited as long as the solar cell encapsulant of the present invention satisfies the above-mentioned condition (i). However, from the viewpoint of improving transparency and flexibility, it is preferably 100 J / g or less, more preferably 90 J / g or less, and even more preferably 80 J / g or less. In order to make the heat of crystal fusion within the above range, components having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry (the aforementioned (A), (B-1-1), ( The total content of B-2-1) and (D)) is preferably 60% by mass or more, more preferably 70% by mass or more, and 75% by mass or more in the sealing material. More preferably. Further, from the viewpoint of heat resistance and prevention of blocking, the heat of crystal melting of the solar cell encapsulant is preferably 10 J / g or more, more preferably 20 J / g or more, and 30 J / g or more. Is more preferable. The range of the heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of the solar cell encapsulant of the present invention is preferably 10-100 J / g, and 20-90 J / g. More preferably, it is 30-80 J / g.
This can be adjusted by the type and content of the components constituting the solar cell encapsulant.

Although the melt flow rate (temperature 190 degreeC, load 21.18N) based on JISK7210 of the solar cell sealing material of this invention is not restrict | limited in particular, Film formability, productivity, glass, and a solar cell From the viewpoint of improving the wettability to cells and the like, it is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and further preferably 2 g / 10 min or more. Further, from the viewpoint of heat resistance, it is preferably 30 g / 10 min or less, more preferably 15 g / 10 min or less, still more preferably 10 g / 10 min or less. In addition, the range of the melt flow rate of the solar cell sealing material of the present invention is preferably 0.5 to 30 g / 10 min, more preferably 1 to 15 g / 10 min, and 2 to 10 g / 10 min. More preferably.
A melt flow rate can be adjusted with the kind and content of the component which comprise a solar cell sealing material.

  The total light transmittance of the solar cell encapsulant of the present invention is preferably 86% or more at a film thickness of 450 μm of the solar cell encapsulant, in order not to significantly reduce the photoelectric conversion efficiency of the solar cell, and 89% More preferably. In addition, total light transmittance can be measured by the method as described in an Example.

  Since the solar cell encapsulant of the present invention has good heat resistance even if it is not crosslinked, it does not need to contain a crosslinking agent such as an organic peroxide, and the silane-modified polyolefin resin and epoxy-modified polyolefin resin Therefore, it does not gel during the molding of the solar cell encapsulant by melting and kneading with an extruder or the like, and is excellent in productivity. Here, it is confirmed that the gelation of the solar cell encapsulating material after being melt-kneaded and molded is less than 1% by mass of the toluene soluble material.

<Method for producing sealing material>
The solar cell encapsulant of the present invention has melt mixing equipment such as a single screw extruder, a multi screw extruder, a Banbury mixer, a kneader, etc., and is a method such as an extrusion casting method using a T die, a calendar method, and an inflation method. Can be manufactured. In the present invention, an extrusion casting method using a T die is preferably used from the viewpoints of handleability and productivity.
Moreover, when a sealing material is a multilayer structure, it can manufacture by coextrusion casting with a multilayer T die using an extruder. The molding temperature in the extrusion casting method using a T-die is appropriately adjusted depending on the flow characteristics and film forming properties of the resin composition to be used, but is generally 130 to 300 ° C, preferably 150 to 250 ° C.
The thickness of the solar cell sealing material of the present invention is not particularly limited, but is preferably 0.03 to 1 mm, more preferably 0.05 to 0.7 mm, and 0.10 to 0 mm. More preferably, it is 5 mm.
It is preferable that one side or both sides of the solar cell encapsulant of the present invention is embossed to prevent blocking.

<Solar cell module>
As the solar cell module using the solar cell encapsulant of the present invention, various types can be exemplified, and specifically, an upper protective material (front sheet) / the encapsulant of the present invention / solar. Battery element / sealing material of the present invention / lower protective material (back sheet), on the solar cell element formed on the inner peripheral surface of the lower protective material, the sealing material of the present invention and the upper protective material On a solar cell element formed on the inner peripheral surface of the upper protective material, for example, an amorphous solar cell element formed on a fluororesin-based transparent protective material by sputtering or the like. The thing of the structure which formed the stop material and the lower part protective material etc. can be mentioned. In addition, in the solar cell module, a junction box (a terminal box for connecting wiring for taking out electricity generated from the solar cells) is usually connected to the outer surface of the lower protective material. More specifically, a wiring is passed through a through hole provided in the lower protective material, the solar battery cell and the junction box are connected by the wiring, and the generated current of the solar battery cell is conducted to the outside.

  Examples of solar cell elements include single crystal silicon type, polycrystalline silicon type, amorphous silicon type, III-V group and II-VI group compound semiconductor types such as gallium-arsenic, copper-indium-selenium, cadmium-tellurium, Examples include a dye sensitizing type and an organic thin film type. Since the sealing material of the present invention can adhere well to transparent electrodes such as indium tin oxide (ITO) film and zinc oxide (ZnO) film used in these solar cell elements, these solar cell elements were used. It can use suitably for a solar cell module.

  About each member which comprises a solar cell module, although it does not specifically limit, single layer or multilayer sheets, such as an inorganic material and various thermoplastic resin films, are used preferably as an upper protective material. In particular, glass is generally used in many cases, and the sealing material of the present invention can be favorably bonded to glass, and thus can be suitably used for such a solar cell module. As the lower protective material, it is a single layer or multilayer sheet such as an inorganic material or various thermoplastic resin films, for example, a sheet made of an inorganic material such as tin, aluminum, stainless steel or glass, an inorganic vapor deposited polyester film, Mention may be made of a single-layer or multilayer sheet-like protective material made of a thermoplastic resin such as a fluorine-containing resin or a polyolefin-based resin. The surface of the upper and / or lower protective material can be subjected to a known surface treatment such as a primer treatment or a corona treatment in order to improve the adhesion to the sealing material or other members.

<Method for manufacturing solar cell module>
The solar cell module of the present invention described above includes, for example, a step of laminating an upper protective material, a sealing material, a solar battery cell, a sealing material and a lower protective material in this order (step 1), and heating by vacuum suction after the step. It can manufacture by the process (process 2) of crimping | bonding. Moreover, when manufacturing the solar cell module of this invention, a batch type manufacturing facility, a roll-to-roll type manufacturing facility, etc. are applicable.
In step 2, it is preferable to use a vacuum laminator under the following conditions.
Temperature: 120 to 180 ° C. (more preferably 125 to 160 ° C., still more preferably 130 to 150 ° C.)
Degassing time: 1 to 15 minutes (more preferably 2 to 10 minutes, more preferably 3 to 8 minutes)
Press pressure: 0.5-1 atm
Press time: 1 to 45 minutes (more preferably 2 to 40 minutes, still more preferably 3 to 30 minutes)

  The solar cell module of the present invention can be applied to various uses regardless of whether it is indoors or outdoors, depending on the type and module shape of the applied solar cell, and whether it is for small size or large size. For example, the present invention can be applied to small solar cells typified by mobile devices, large solar cells installed on the roof or rooftop, and the like.

  EXAMPLES The present invention will be described in more detail with reference to examples. However, the present invention is not limited by these examples and comparative examples. Various measurements and evaluations on the resins (A), (B-1), (B-2), (C-1), (C-2) and the sealing material in this example were performed as follows. It was.

(Melting point)
Using a differential scanning calorimeter (manufactured by PerkinElmer Co., Ltd., trade name: Pyris1 DSC), according to JIS K7121, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 200 ° C. for 5 minutes, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min. Asked.

(Crystal melting heat (ΔH))
Using a differential scanning calorimeter (trade name: Pyris1 DSC, manufactured by Perkin Elmer Co., Ltd.), approximately 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min in accordance with JIS K7122. After holding at 200 ° C. for 5 minutes, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min ( J / g), a crystal melting heat quantity (J / g) of 90 ° C. or higher, and a crystal melting heat quantity (J / g) of 120 ° C. or higher were determined.
Note that the heat of crystal melting above a certain X ° C. is calculated from the melting peak area above the X ° C. A method for calculating the heat of crystal melting above X ° C. will be described with reference to FIG.
Fig. 1 shows three calculation methods (Fig. 1 (1) When melting peak temperature> X ° C; Fig. 1 (2) When melting peak temperature ≒ X ° C; Fig. 1 (3) Melting peak temperature <X ° C Case). The heat of crystal melting above X ° C. is calculated from the hatched portion in the thermogram shown in FIG.

(Melt flow rate (MFR))
According to JISK7210, MFR (g / 10 min) was measured at 190 ° C. and a load of 21.18 N.

(density)
The density was measured by a density gradient tube method according to JISK7112.

(Adhesive evaluation with transparent electrode (ZnO))
Glass with a transparent electrode (manufactured by Geomat Co., Ltd., 10 cm x 10 cm x 1.1 mm thickness) is lined with a glass plate of 15 cm x 15 cm x 3 mm thickness, and the solar cell seal produced in Examples and Comparative Examples on the transparent electrode side A back sheet (made by Covime, trade name: dyMat PYE, total thickness 295 μm, laminated structure EVA / EVA (white; containing titanium oxide) / EVA / PET / PET (white; containing barium sulfate) is placed thereon. ) And vacuum pressed under conditions of 150 ° C. for 10 minutes (breakdown, vacuuming: 5 minutes, pressing: 5 minutes) to prepare a sample. At this time, a release PET film was sandwiched between a part between ZnO and the sealing material in order to make a handle portion at the time of the peel test. Next, using a tensile tester (manufactured by INTESCO, product name: 200X type tester), a peel test was performed under conditions of a peel angle of 180 ° and a peel speed of 50 mm / min. The adhesiveness was evaluated according to the following criteria from the maximum detected load in the peel test.
(◯) The maximum detection load is 50 N / cm or more (×) The maximum detection load is less than 50 N / cm In addition, regarding the sample that is (◯) in the above evaluation, it is 200 in a constant temperature and humidity chamber at 85 ° C. and 85% Rh. After standing for a period of time (200 hours after the dump heat test), the peel test was performed again to evaluate the adhesion.

(Evaluation of adhesion to glass)
The solar cell encapsulant produced in Examples and Comparative Examples was placed on the embossed surface of 15 cm × 15 cm × 3 mm embossed glass (manufactured by Asahi Glass Co., Ltd., trade name: Solite), and a back sheet ( Product name: dyMat PYE, total thickness of 295 μm, laminated structure EVA / EVA (white; containing titanium oxide) / EVA / PET / PET (white; containing barium sulfate)), 150 ° C., 10 minutes (breakdown) The sample was made by vacuum pressing under the conditions of vacuuming: 5 minutes, pressing: 5 minutes. At this time, a release PET film was sandwiched between a part of the embossed glass and the sealing material to form a handle part during the peel test. Next, using a tensile tester (manufactured by INTESCO, product name: 200X type tester), a peel test was performed under conditions of a peel angle of 180 ° and a peel speed of 50 mm / min. The adhesiveness was evaluated according to the following criteria from the maximum detected load in the peel test.
(◯) The maximum detection load is 50 N / cm or more (×) The maximum detection load is less than 50 N / cm In addition, regarding the sample that is (◯) in the above evaluation, it is 200 in a constant temperature and humidity chamber at 85 ° C. and 85% Rh. After standing for a period of time (200 hours after the dump heat test), the peel test was performed again to evaluate the adhesion.

(Evaluation of transparency)
The solar cell sealing materials produced in the examples and comparative examples were stacked between two pieces of white plate glass having a thickness of 3 mm (manufactured by SCHOTT, trade name: B270, size: length 75 mm, width 25 mm), and a vacuum press was used. Then, a sample that was laminated and pressed under the conditions of a set temperature of 150 ° C., a vacuum time of 5 minutes, and a press time of 30 seconds was prepared, and a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: NDH-5000) according to JISK7105. ) Was used to measure the total light transmittance and evaluated according to the following criteria.
(◎) Total light transmittance is 89% or more (○) Total light transmittance is 86% or more and less than 89% (×) Total light transmittance is less than 86%

(Heat-resistant)
Using a vacuum press machine, a white plate glass 101 having a thickness of 3 mm in order from the hot plate side under the conditions of 150 ° C. for 10 minutes (breakdown, vacuum drawing: 5 minutes, press: 5 minutes) (size: length 150 mm, width 50 mm), A sheet-like sealing material 102 (size: length 75 mm, width 26 mm) having a cut thickness of 0.45 mm and a slide glass 103 (size: length 75 mm, width 26 mm, mass 5.4 g) are stacked and laminated. Pressed. Thereafter, a stainless steel plate 104 (size: length 75 mm, width 26 mm, mass 28 g) was bonded onto the slide glass to prepare a sample for creep test (load applied to the sealing material: 1.5 g / cm ² ) (FIG. 2 ( a) and FIG. 2 (b)). This sample was left in an oven at 90 ° C. for 20 hours at an angle of 90 °, and the heat resistance was judged as follows from the shifted distance of the slide glass 103 (see FIG. 2C).
(◎) The shifted distance is less than 1 mm (◯) The shifted distance is 1 mm or more and less than 2 mm (×) The shifted distance is 2 mm or more.

(Gel fraction)
About 0.4 g of the sealing material obtained in Examples and Comparative Examples was extracted in boiling toluene for 12 hours, and the gel fraction was calculated from the amount of insoluble components.

-The raw material which comprises a sealing material is described below.
Polyolefin resin (A) having a melting point of less than 90 ° C .:
(A) Ethylene-octene random copolymer (manufactured by Mitsui Chemicals, trade name: Tafmer H5030S, MFR: 5, density: 0.870 g / cm ³ , melting point: 59 ° C., heat of crystal melting: 48 J / g, 90 ° C. or higher) Of crystal melting: 0 J / g, octene content: 32.4% by mass)

Silane-modified polyolefin resin (B-1):
(B-1-1) Silane-modified ethylene-propylene-hexene copolymer (manufactured by Mitsubishi Chemical, trade name: Linkron SS732N, MFR: 13, density: 0.885 g / cm ³ , melting point: 60 ° C., heat of crystal melting : 40 J / g, propylene content: 12% by mass, hexene content: 8% by mass)
(B-1-2) Silane-modified ethylene-butene random copolymer (manufactured by Mitsubishi Chemical, trade name: Linkron XLE815N, MFR: 0.5, density: 0.915 g / cm ³ , melting point: 120 ° C., crystal melting (Amount of heat: 110 J / g, heat of crystal melting at 90 ° C. or higher: 78 J / g, heat of crystal melting at 120 ° C. or higher: 16 J / g, butene content: 8% by mass)

Epoxy-modified polyolefin resin (B-2):
(B-2-1) Ethylene-methacrylate-glycidyl methacrylate copolymer (manufactured by Arkema, trade name: Rotada GMA AX8900, MFR: 6, density: 0.950 g / cm ³ , melting point: 60 ° C., heat of crystal melting: 48 J / g, glycidyl methacrylate content: 8% by mass, methacrylate content: 24% by mass, heat of crystal melting at 90 ° C. or higher: 0 J / g)
(B-2-2) Ethylene-glycidyl methacrylate copolymer (manufactured by Arkema Co., Ltd., trade name: Rotada GMA AX8840, MFR: 5, density: 0.940 g / cm ³ , melting point: 109 ° C., heat of crystal melting: 105 J / g, heat of crystal fusion at 90 ° C. or higher: 50 J / g, heat of crystal fusion at 120 ° C. or higher: 0 J / g, glycidyl methacrylate content: 8% by mass)

Polyolefin resin (C) having a melting point of 90 ° C. or higher:
(C-1) Ethylene-octene multiblock copolymer (manufactured by Dow Chemical Co., Ltd., trade name: Infuse9000, MFR: 0.5, density: 0.875 g / cm ³ , melting point: 120 ° C., heat of crystal melting: 46 J / G, heat of crystal fusion at 90 ° C. or higher: 40 J / g, heat of crystal fusion at 120 ° C. or higher: 13 J / g, octene content: 30% by mass)
(C-2) Ethylene-butene random copolymer (manufactured by Prime Polymer Co., Ltd., trade name: NEOZEX0234N, MFR: 2, density: 0.919 g / cm ³ , melting point: 120 ° C., heat of crystal melting: 106 J / g, 90 (Crystal melting heat of ℃ ≧ 85 J / g, Crystal melting heat of 120 ℃ or more: 15 J / g, Butene content: 7% by mass)

Example 1
(A) 80% by mass, (B-1-1) 5% by mass, (B-1-2) 5% by mass, (B-2-1) 10% by mass of resin composition mixed After extrusion molding at a resin temperature of 180 ° C. to 200 ° C. by a T-die method using the same-direction twin-screw extruder, the film was quenched with a cast embossing roll at 25 ° C., and a single-layer solar cell encapsulating with a total thickness of 450 μm A stop was obtained. Evaluation was performed as described above using the obtained sealing material. The results are shown in Table 1.

Examples 2-3
A sealing material was prepared and evaluated in the same manner as in Example 1 except that the resin composition used was changed to the formulation shown in Table 1. The results are shown in Table 1.

Example 4
(I) As a layer, it mixed in the ratio of (A) 80 mass%, (B-1-1) 5 mass%, (B-1-2) 5 mass%, and (B-2-1) 10 mass%. (I) layer / (II) layer / (II) layer, using (A) 95% by mass, and (C-2) 5% by mass of the resin composition mixed respectively. (I) After co-extrusion molding at a resin temperature of 180 to 200 ° C. by a T-die method using a co-directional twin-screw extruder so as to be laminated in the order of layers, the film is rapidly cooled with a cast embossing roll at 25 ° C. As a result, a solar cell encapsulating material ((I) layer / (II) layer / (I) layer = 45 μm / 360 μm / 45 μm) having a total thickness of 450 μm was obtained. Evaluation was performed as described above using the obtained sealing material. The results are shown in Table 1.

Example 5
A sealing material was prepared and evaluated in the same manner as in Example 4 except that the resin composition used was changed to the formulation shown in Table 1. The results are shown in Table 1.

Comparative Examples 1-5
A sealing material was prepared and evaluated in the same manner as in Example 1 except that the resin composition used was changed to the formulation shown in Table 1. The results are shown in Table 1.

From Examples 1 to 5 in Table 1, (A) a polyolefin resin having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry, (B-1) a silane-modified polyolefin resin, (B -2) It contains an epoxy-modified polyolefin-based resin, and the crystal melting calorie (ΔH _{≧ 90 ° C.} ) of _{90 °} C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 1.5-30 J / g. The encapsulant is a solar cell encapsulant with excellent adhesion, heat resistance, and transparency. On the other hand, since Comparative Example 1 does not contain (B-1) a silane-modified polyolefin resin, the adhesiveness to glass is inferior. Moreover, in the comparative example 2, since it does not contain (B-2) epoxy modified polyolefin resin, it is inferior to the adhesiveness to a transparent electrode. In Comparative Example 3, (A) a polyolefin resin having a melting point of less than 100 ° _C. is not contained, and ΔH _{≧ 90 ° C.} is large, so that the transparency is poor. Further, Comparative Examples 4 and 5 contain (A), (B-1), and (B-2), but the range of ΔH _{≧ 90 ° C.} is outside the scope of the present invention, and transparency and heat resistance. Sexual compatibility is not achieved.

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell sealing material which was excellent in the adhesiveness to glass or a photovoltaic cell, and was excellent in heat resistance and transparency, and a solar cell module using the same are obtained.

101: White plate glass 102: Sealing material 103: Slide glass 104: Stainless steel plate

Claims (6)

A solar cell encapsulating material characterized by having at least one adhesive layer containing the following (A), (B-1) and (B-2) in the outermost layer and satisfying the following condition (i): .
(A) Polyolefin resin (B-1) Silane-modified polyolefin resin (B-2) Epoxy-modified polyolefin resin (i) having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry The crystal melting calorie (ΔH _{≧ 90 ° C.} ) measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 1.5-30 J / g.   The said (B-1) contains the silane modified polyethylene resin whose melting | fusing point measured at the heating rate of 10 degree-C / min in differential scanning calorimetry is 90 degreeC or more, The sun of Claim 1 characterized by the above-mentioned. Battery encapsulant.   The said (B-2) contains the epoxy-modified polyethylene-type resin whose melting | fusing point measured by the heating rate of 10 degree-C / min in differential scanning calorimetry is 90 degreeC or more, It is characterized by the above-mentioned. Solar cell encapsulant. The solar cell encapsulant according to claim 1, wherein the adhesive layer further contains (C) below.
(C) Polyolefin resin having a melting point of 90 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry. Furthermore, it has layers other than the said adhesive layer, and layers other than this adhesive layer contain the following (D) and (E), and satisfy | fill the following conditions (ii), It is characterized by the above-mentioned. The solar cell sealing material in any one.
(D) Polyolefin resin having a melting point of less than 90 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry (E) A melting point of 90 ° C. or more measured at a heating rate of 10 ° C./min in differential scanning calorimetry Polyolefin resin (ii) The heat of crystal fusion (ΔH _{≧ 90 ° C.} ) of _{90 °} C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry is 1.5-30 J / g.   The solar cell module using the solar cell sealing material in any one of Claims 1-5.

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