KR20140147714A - Encapsulation sheet - Google Patents

Abstract

The present invention relates to an encapsulation sheet including a silane-graft modified ethylene-alpha-olefin copolymer. The silane-graft modified ethylene-alpha-olefin copolymer is obtained by grafting alcoxy silane-based compound into ethylene-alpha-olefin copolymer by radical polymerization. More specifically, the number of the alcoxy silnane group, grafted in the elthlyene-alpha-olefin copolymer and the silane-graft modified ethylene-alpha-olefin copolymer, can be one per 100-4,000 carbon atoms.

Description

ENCAPSULATION SHEET [0002]

The present application relates to an encapsulating material sheet.

The encapsulant sheet can be used to protect devices or devices sensitive to external factors such as moisture or oxygen. Devices or devices that can be protected by the encapsulant sheet include, for example, organic electronic devices, secondary batteries such as photovoltaic or lithium secondary batteries, and the like.

Photovoltaic (PV) solar photovoltaic (PV) technology is a device that converts sunlight into electric energy. Since it is required to be exposed to the external environment for a long time in order to easily absorb sunlight, various packaging for protecting the cell is performed, ), And these units are referred to as photovoltaic modules.

1 is a view schematically showing a structure of a photovoltaic module. Generally, the photovoltaic module includes a backsheet 3 made of weather-resistant plastic, and a backsheet 3 made of a weather-resistant plastic. The backsheet 3 is made of weather- As shown in FIG. As encapsulants used in photovoltaic modules, ethylene-vinyl acetate copolymer resins (EVA) are generally used in terms of processability, manufacturing cost, and transparency. However, the encapsulant containing the ethylene-vinyl acetate copolymer resin has poor moisture barrier properties, so that the adhesive strength to the photovoltaic device or the tempered glass substrate is not sufficient under the high-temperature wet condition, and the interlayer peeling phenomenon occurs during prolonged use . In addition, acetic acid gas is generated by a hydrolysis reaction by moisture permeation, which causes electrode corrosion or problems such as foaming, and ultimately causes a decrease in the efficiency of the photovoltaic module.

When the ethylene-vinyl acetate copolymer resin is used in a photovoltaic module encapsulant, a separate curing process is performed in order to impart sufficient heat resistance. Such a curing process requires a relatively long time of about 15 to 60 minutes , The production speed and production efficiency of the photovoltaic module are lowered.

The present application provides an encapsulating sheet.

One embodiment of the present application provides an encapsulation sheet comprising (a) an ethylene-alpha olefin copolymer and (b) a silane graft-modified ethylene-alpha olefin copolymer.

The encapsulating material sheet of the present application contains an ethylene-alpha olefin copolymer and is excellent in moisture barrier property, and further includes a silane graft-modified ethylene-alpha olefin copolymer to provide excellent adhesion to a photovoltaic module member, .

Since the ethylene-alpha olefin copolymer has a lower moisture permeability and does not generate hydrolysis products such as acetic acid and the like compared with the ethylene-vinyl acetate copolymer resin (EVA), the reliability of the photovoltaic module It is material that can raise. However, in order to use an ethylene-alpha olefin copolymer as an encapsulating material, it is necessary to satisfy physical properties such as transparency and adhesiveness required by the encapsulating material. In order to impart adhesiveness to the ethylene-alpha-olefin copolymer, a silane-modified ethylene-alpha olefin copolymer grafted with an alkoxysilane compound onto an ethylene-alpha olefin copolymer was introduced, It is necessary to control the number of alkoxysilane groups grafted in terms of transparency and the like.

The number of grafted alkoxysilane groups includes the total ethylene-alpha olefin copolymer contained in the encapsulating material sheet, that is, (a) ethylene-alpha olefin copolymer and (b) silane graft-modified ethylene-alpha olefin copolymer The number of alkoxysilane groups grafted onto the entire ethylene-alpha olefin copolymer may be one per 100 to 4,000 carbon atoms. In the above, the number of alkoxysilane groups grafted to the entire ethylene-alpha olefin copolymer may be determined based on the number of carbon atoms. For example, a proper number of silane functional groups are required for improving the adhesion of the sealing sheet. When calculating the number of silane functional groups based on the weight ratio or the molar ratio of the grafted silane, the same mole or weight ratio silane is grafted The number of silane functional groups can be reduced in the case of a silane having a large molecular weight and the number of silane functional groups can be relatively increased in a case of a silane having a small molecular weight. In this case, even when the same molar ratio or weight ratio of silane is grafted, the adhesive force of the sealing material sheet varies depending on the molecular weight of the silane. Therefore, the total number of silane functional groups, which are directly related to the adhesive force of the sealing material sheet, By controlling the number of carbon atoms of the alpha olefin copolymer, it is possible to control the number of silane functional groups suitable for improving the adhesion.

The alpha olefin of the ethylene-alpha olefin copolymer may be selected from the group consisting of propylene, 1-butene, isobutylene, 2-methyl-1-butene, Hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, , Ethylidene norbornene, phenyl norbornene, vinyl norbornene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, alpha-methylstyrene, 3-chloromethylstyrene, and the like.

The ethylene-alpha olefin copolymer may be prepared using a catalyst composition comprising a transition metal compound represented by the following formula (1).

[Chemical Formula 1]

Wherein R 1 and R 2 are the same or different and are each independently selected from the group consisting of hydrogen, a halogen radical, an alkyl radical having 1 to 20 carbon atoms, an alkenyl radical having 2 to 20 carbon atoms, an aryl radical having 6 to 20 carbon atoms, a silyl radical, An alkylaryl radical having 7 to 20 carbon atoms, an arylalkyl radical having 7 to 20 carbon atoms, or a metalloid radical of a Group 4 metal substituted with hydrocarbyl, wherein R 1 and R 2 or two R 2 are alkyl or C 1 -C 20 And R < 3 > may be the same or different and are each independently selected from the group consisting of hydrogen, a halogen radical, an alkyl radical having 1 to 20 carbon atoms, an alkyl radical having 1 to 20 carbon atoms An alkenyl radical having 2 to 20 carbon atoms, an aryl radical having 6 to 20 carbon atoms, an alkylaryl radical having 7 to 20 carbon atoms, an arylalkyl having 7 to 20 carbon atoms An alkoxy radical having from 1 to 20 carbon atoms, an aryloxy radical having from 6 to 20 carbon atoms or an amido radical, two or more of R3's are connected to each other to form an aliphatic ring or aromatic ring, and CY1 is substituted or unsubstituted Wherein the substituent group is a halogen radical, an alkyl radical having 1 to 20 carbon atoms, an alkenyl radical having 2 to 20 carbon atoms, an aryl radical having 6 to 20 carbon atoms, an alkylaryl radical having 7 to 20 carbon atoms , An arylalkyl radical having 7 to 20 carbon atoms, an alkoxy radical having 1 to 20 carbon atoms, an aryloxy radical having 6 to 20 carbon atoms, or an amido radical, and when the number of the substituents is plural, two or more substituents An aliphatic or aromatic ring, M is a Group 4 transition metal, and Q1 and Q2 are Independently of one another are a halogen radical, an alkyl radical of 1 to 20 carbon atoms, an alkenyl radical of 2 to 20 carbon atoms, an aryl radical of 6 to 20 carbon atoms, an alkylaryl radical of 7 to 20 carbon atoms, an arylalkyl radical of 7 to 20 carbon atoms An alkylamido radical having 1 to 20 carbon atoms, an arylamido radical having 6 to 20 carbon atoms or an alkylidene radical having 1 to 20 carbon atoms.

The catalyst composition may further include at least one of the promoter compounds represented by the following general formulas (2), (3) and (4).

(2)

- [Al (R &_lt; 8 >) - O] _n -

In the general formula (2), R 8 may be the same or different from each other, and each independently represents a halogen, a hydrocarbon of 1 to 20 carbon atoms, or a hydrocarbon of 1 to 20 carbon atoms substituted with a halogen, n is an integer of 2 or more,

(3)

D (R 8) ₃

In Formula 3, R8 is the same as defined in Formula 2, D is aluminum or boron,

[Chemical Formula 4]

[LH] ⁺ [ZA ₄ ] ^- or [L] ⁺ [ZA ₄ ] ^-

In Formula 4, L is a neutral or cationic Lewis acid, H is a hydrogen atom, Z is a Group 13 element, A may be the same or different from each other, and independently at least one hydrogen atom is substituted with halogen, An aryl group having 6 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms, which is substituted or unsubstituted with a hydrocarbon, alkoxy or phenoxy.

The ethylene-alpha olefin copolymer (a) and the ethylene-alpha olefin copolymer (b) of the silane graft-modified ethylene-alpha olefin copolymer contained in the encapsulating material sheet of the present application may be the same or different. That is, a silane graft-modified ethylene-alpha olefin copolymer in which an alkoxysilane-based compound is graft-modified to an ethylene-alpha olefin copolymer as a base resin may be included, and an alkoxy silane A silane graft-modified ethylene-alpha olefin copolymer graft-modified with a base compound may also be used.

In addition, the encapsulating material sheet of the present application may not contain the ethylene-alpha olefin copolymer (a) as an optional component as long as it contains the silane graft-modified ethylene-alpha olefin copolymer (b). For example, the content ratio of the ethylene-alpha olefin copolymer (a) and the silane graft-modified ethylene-alpha olefin copolymer (b) in the sealing sheet of the present application may be from 0: 100 to 95: 5.

Wherein (a) an ethylene-density alpha-olefin copolymer may be from 0.85 to 0.89 g / cm ³ days, (b) the silane-graft modified ethylene-density alpha-olefin copolymer 0.85 to 0.89 g / cm ³ can be have.

The silane graft-modified ethylene-alpha olefin copolymer (b) has an alkoxysilane functional group introduced into the side chain or terminal, and the alkoxysilane compound used for the modification includes a double bond capable of radical graft polymerization. Figure 2 illustrates the structure of an alpha-olefin copolymer grafted with an alkoxysilane.

For example, the alkoxysilane compound may be represented by the following general formula (5), but is not limited thereto.

[Chemical Formula 5]

DSi (X) _m Y _(3-m)

X represents an alkoxy group bonded to a silicon atom; Y represents an alkyl group bonded to a silicon atom; and m represents an integer of 1 to 3.

The alkenyl group may be, for example, a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, a hexenyl group, a cyclohexenyl group or an octenyl group.

In the compound of Formula 5, D may be grafted to the ethylene-alpha olefin copolymer resin in the presence of a radical initiator to form a silane graft-modified ethylene-alpha olefin copolymer.

The alkyl group in Formula 5 may be an alkyl group having 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. The alkyl group may be a straight chain, branched chain or cyclic alkyl group.

In the above formula (5), an alkoxy group having 1 to 20 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms or 1 to 4 carbon atoms may be exemplified. The alkoxy group may be linear, branched or cyclic.

The alkyl group, alkoxy group and the like may be optionally substituted with one or more substituents. Examples of the substituent include a hydroxyl group, an epoxy group, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an acyl group, a thiol group, an acryloyl group, a methacryloyl group, an aryl group or an isocyanate group. But is not limited to.

Examples of the alkoxysilane compound include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane, vinyltriphenoxysilane , Vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, vinyltricarboxysilane, vinyltris (? -Methoxyethoxysilane), Allyltrimethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, allyltrimethoxysilane, allyltrimethoxysilane, allyltrimethoxysilane, allyltrimethoxysilane, allyltrimethoxysilane, allyltrimethoxysilane, allyltrimethoxysilane, Allyltriethoxysilane, allyltricarboxysilane, allyltris (? -Methoxyethoxysilane),? -Methyltriethoxysilane, allyltriethoxysilane, allyltriethoxysilane, Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane,? -Methacryloxypropyltrimethoxysilane, .

As the ethylene-alpha olefin copolymer in which the unsaturated silane compound is grafted in the production of the silane graft-modified ethylene-alpha olefin copolymer (b), the grafting efficiency may be increased by using a copolymer having many side chains. A polyolefin having a large number of side chains has a low density and a polyolefin having a small number of side chains has a high density. Thus, in the present application, an ethylene-alpha olefin copolymer which is a low density polyolefin may be used, and for example, the density may be 0.85 to 0.96 g / cm ³ or 0.85 to 0.92 g / cm ³ .

The molecular weight distribution (Mw / Mn) of the ethylene-alpha olefin copolymer may be less than 3.5, for example, 1.2 to 3.5, 1.5 to 3.3, and the like.

The ethylene-alpha olefin copolymer may have a melt flow rate (MFR) at 190 DEG C of about 0.1 g / 10 min to about 50 g / 10 min, for example, about 1.0 g / 10 min to about 50 g / 10 min Min, about 1.0 g / 10 min to about 30 g / 10 min. When the MFR is in this range, an encapsulating material sheet having excellent moldability and adhesiveness can be provided.

The sealing material sheet may further include at least one additive selected from the group consisting of an ultraviolet absorber, a light stabilizer, a heat stabilizer, an antioxidant and a moisture adsorbent, if necessary.

The ultraviolet absorber may act to absorb ultraviolet rays from sunlight or the like and convert the ultraviolet absorber into harmless thermal energy in the molecule to prevent excitation of the active-thermal initiator in the alpha-olefin copolymer have. Specific examples of the ultraviolet absorber usable in the present invention are not particularly limited and include benzophenone, benzotriazole, acrylonitrile, metal complex salt, hindered amine, ultrafine titanium oxide, ultrafine zinc oxide Inorganic ultraviolet absorbers and the like, or a mixture of two or more thereof.

The light stabilizer can capture the active species of the photoalignment initiation of the alpha olefin copolymer to prevent photo-oxidation. The type of light stabilizer that can be used is not particularly limited, and examples thereof include known compounds such as hindered amine compounds and hindered piperidine compounds.

Examples of the heat stabilizer include tris (2,4-di-tert-butylphenyl) phosphite, bis [2,4-bis (1,1-dimethylethyl) -6- methylphenyl] ethyl ester phosphorous acid, tetrakis Di-tert-butylphenyl) [1,1-biphenyl] -4,4'-diyl bisphosphonate and bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite. stabilizator; And a reaction product of 8-hydroxy-5,7-di-tert-butyl-furan-2-one and o-xylene, and a mixture of at least one of them or a mixture of two or more thereof Can be used.

The moisture adsorbent may mean, for example, a material capable of adsorbing or removing moisture through chemical reaction or physical reaction with water or moisture penetrated into the sealing material sheet.

Examples of the moisture adsorbent that can be used in the above include metal oxides, sulfates, organic metal oxides, clays, talc, needle-like silica, plate-like silica, porous silica, zeolite, titania or zirconia. Specifically, examples of the metal oxide include magnesium oxide, calcium oxide, strontium oxide, barium oxide, and aluminum oxide. Examples of the sulfate include magnesium sulfate, sodium sulfate, and nickel sulfate. Examples of the organic metal oxides include aluminum oxide octylate and the like.

In the encapsulating material sheet, the content of additives such as an ultraviolet absorber, a light stabilizer, a heat stabilizer, an antioxidant and the like is not particularly limited and may be appropriately added as needed. That is, the content of the additive may be appropriately selected in consideration of the use of the encapsulating material sheet, the shape and the density of the additive, and is suitably adjusted within the range of 0.01 wt% to 5 wt% .

The encapsulating material sheet may suitably further include various additives known in the art depending on the application to which the composition is applied.

The shape of the encapsulation material sheet is not particularly limited and may be in the form of a sheet or film. In this case, the thickness of the sealing material sheet may be about 10 to 2,000 mu m in consideration of support efficiency and breakage of devices such as photovoltaic cells, light weight of the device, workability, etc. For example, 1.25 mm, 0.1 mm to 1 mm. However, the thickness of the encapsulant sheet may vary depending on the specific application to which it is applied.

The light transmittance of the encapsulating material sheet may be 91% or more and may be applied to a product in which transparency must be secured, and the water vapor transmission rate (WVTR) may be 1.0 to 5.0 g / m ² · 1day. The moisture permeation amount can be measured based on the weighing method (JIS Z0208 standard), and is a measured value in the thickness direction of the sealing material sheet.

The encapsulation material sheet may further include, for example, a substrate. The substrate may be disposed on one side or both sides of the sheet, for example. The substrate may be, for example, a substrate subjected to a releasing treatment, and such substrate may be used without limitation in the art.

The encapsulation sheet can be applied to encapsulate and protect various objects. In particular, the encapsulant sheet may be effective in protecting an object comprising an external component, for example, a device sensitive to moisture or moisture. Examples of objects to which the encapsulant sheet can be applied include organic electronic devices such as a photovoltaic device, a rectifier, a transmitter or an organic light emitting diode (OLED); Solar cell; Or secondary batteries, but the present invention is not limited thereto.

The method for producing the encapsulation material sheet is not particularly limited. For example, there is provided a process for preparing a resin composition comprising (a) an ethylene-alpha olefin copolymer and (b) silane graft-modified ethylene-alpha olefin copolymer, and processing the resin composition into a sheet or film . ≪ / RTI >

The step of preparing a resin composition comprising (a) an ethylene-alpha-olefin copolymer and (b) a silane graft-modified ethylene-alpha olefin copolymer can be carried out, for example, by reacting ethylene- Olefin < RTI ID = 0.0 > copolymer. ≪ / RTI > The method for producing the ethylene-alpha olefin copolymer into which the alkoxysilane group is introduced in the reactor is not particularly limited. For example, by mixing an ethylene-alpha olefin copolymer and an unsaturated silane compound as described above in a molten state in a reactor and grafting the unsaturated silane compound to the ethylene-alpha olefin copolymer in the presence of a suitable radical initiator Can be manufactured.

The type of the reactor in which the ethylene-alpha olefin copolymer is produced is not particularly limited as long as it is capable of reacting reactants in a heated or molten state to produce a desired resin. For example, the reactor may be an extruder or a cylinder. For example, the liquid phase unsaturated silane compound and the radical initiator may be added to the ethylene-alpha olefin copolymer heated and melted through the extruder and extruded, or the ethylene-alpha olefin copolymer, the radical initiator and the unsaturated silane compound may be mixed And then heated and melted in a silander and reacted to prepare a silane graft modified ethylene-alpha olefin copolymer.

The additives contained in the encapsulation material sheet may be introduced into the reactor as it is, or may be added and mixed in the form of a master batch. The master batch means a pellet-shaped raw material in which the additive to be added is concentrated and dispersed at a high concentration. Usually, in the process of molding the plastic raw material by a method such as extrusion or injection, To be introduced.

The method for introducing an additive such as a hydrolysis catalyst into the reactor in which the silane graft-modified ethylene-alpha olefin copolymer is formed is not particularly limited. For example, a side feeder may be installed at an appropriate position of the extruder or cylinder, A method in which a master batch type additive is fed through the feeder, or a method in which the mixture is mixed with an ethylene-alpha olefin copolymer or the like in a hopper.

The conditions such as the specific kind of the reactor, the design, the heating and melting, the mixing or the temperature and the time of the reaction, the kind of the radical initiator and the production method of the master batch are not particularly limited and may be appropriately selected in consideration of the raw materials to be used .

There is also no particular limitation on the method of molding the composition obtained after the above-described process into a sheet or film, and for example, a conventional filming or sheeting process such as a T-die process or extrusion can be used .

In the present application, it is possible to provide an encapsulating material sheet excellent in moisture barrier property, superior in transparency due to uniform distribution of alpha-olefin comonomers, and excellent in adhesion to a photovoltaic module member, Unlike the conventional EVA sheet, a separate curing process is not necessary, so that the production speed of the photovoltaic module can be improved and excellent production efficiency can be provided.

1 is a view schematically showing a structure of a photovoltaic module.
Figure 2 shows the structure of an alpha-olefin copolymer grafted with an alkoxysilane.

Hereinafter, the encapsulation material sheet will be described in detail by way of examples and comparative examples, but the scope of the encapsulation material sheet is not limited to the examples shown below.

Manufacturing example  1 to 5 - masterbatch manufacture

A master batch was prepared using a twin extruder (Micro 27, Leistriz) with the composition shown in Table 1 below.

(1) Production of Silane Master Batch

To prepare the silane master batch, the ethylene-alpha olefin copolymer was fed into a Lupersol 101 catalyst mixture phase in a twin-screw extruder (L / D = 40, diameter 27 mm, retention time 1 min, pressure 23 bar) Was subjected to a graft reaction with the silane monomer to prepare a vinylsilane-modified ethylene-alpha olefin copolymer. At this time, the silane masterbatch was prepared by controlling the amount and type of the silane monomer to be added and the amount of the peroxide catalyst. The reaction temperature of the extruder at the portion where the ethylene-alpha olefin copolymer and the silane were charged was 50 ° C, the reaction portion under the nitrogen injection was 210 ° C, and the discharge temperature after completion of the reaction was 140 ° C.

(2) Additive masterbatch manufacturing

To prepare the additive masterbatch, add the antioxidant, ultraviolet stabilizer and ultraviolet absorber in a twin-screw extruder (L / D = 40, diameter 27 mm, retention time 1 min, pressure 23 bar) Batch. The reaction temperature of the extruder at the portion where the ethylene-alpha olefin copolymer and the additive were introduced was 50 ° C, the melt-kneading portion under the nitrogen injection was 210 ° C, and the extrusion temperature after kneading was 140 ° C.

Master batch Furtherance Feed-in content (wt%)
Production Example 1 Ethylene-alpha olefin copolymer 97.14 Vinyltrimethoxysilane 2.8 Peroxide 0.06
Production Example 2 Ethylene-alpha olefin copolymer 94.9 Vinyltrimethoxysilane 5 Peroxide 0.1
Production Example 3
Ethylene-alpha olefin copolymer 91.6 Vinyltrimethoxysilane 8.2 Peroxide 0.16
Production Example 4
Ethylene-alpha olefin copolymer 94.9 Vinyltriethoxysilane 5 Peroxide 0.1
Production Example 5
Ethylene-alpha olefin copolymer 94.9 3-methacryloxypropyltrimethoxysilane 5 Peroxide 0.1

Additive master batch

Ethylene-alpha olefin copolymer 94 Ultraviolet absorber 2 Ultraviolet stabilizer 2 Antioxidant 1 One Antioxidant 2 One

* Ethylene-alpha olefin copolymers, polyethylene elastomers LC670 ^{(density: 0.870 g / cm 3),} ( Note) LG Chemical

* Vinyltrimethoxysilane: Korea Biogen Co., Ltd.

* Vinyltrimethoxysilane: Korea Biogen Co., Ltd.

* 3-Methacryloxypropyl trimethoxysilane: 3-methacryloxypropyl trimethoxysilane: Korea Biogen Co., Ltd.

Peroxide: Lupersol 101 (2,5-bis (t-butylperoxy) -2,5-dimethylhexane), Aldrich

Antioxidant 1: Irganox 1076 (octadecyl 3,5-di (tert) -butyl-4-hydroxyhydrocinnamate), BASF

Antioxidant 2: Irgafos 168 (tris (2,4-di-tert-butylphenyl) phosphite), BASF

Analysis example  One

The degree of silane grafting to the silane-modified ethylene-alpha olefin prepared in Preparation Examples 1 to 5 was confirmed by nuclear magnetic resonance analysis (NMR). The instrument used was ¹ H high-temperature solution NMR (Bruker DRX 600 MHz NMR). The experimental conditions were as follows: The sample was dissolved in Tetrachloroethane (TCE) -d ₂ solvent at high temperature and measured at 100 ° C. ^{Based on the 1} H NMR peak integral, the molar ratio and weight ratio of the grafted silane to the unreacted silane was calculated. Grafting silane contributes to the improvement of adhesion, but unreacted silane does not contribute to the improvement of adhesion. The degree to which the silane calculated by NMR analysis was grafted is shown in Table 2 below.

Composition ratio (molar ratio) Name of sample PE
(100.0 normalize) 1-octene Silane monomer The number of carbon atoms per Si-O-R
Production Example 1 100.0
(Carbon number: 200) 13.7
(Carbon number: 109.6) 0.5
(Number of carbon atoms: 1, number of Si-O-CH ₃ : 1.5) 207
Production Example 2 100.0
(Carbon number: 200) 13.2
(Carbon number: 105.6) 0.9
(Number of carbon atoms: 1.8, number of Si-O-CH ₃ : 2.7) 114
Production Example 3 100.0
(Carbon number: 200) 12.5
(Carbon number: 100) 1.6
(Number of carbon atoms: 3.2, number of Si-O-CH ₃ : 4.8) 63
Production Example 4 100.0
(Carbon number: 200) 14.6
(Carbon number: 116.8) 1.0
(Number of carbon atoms: 2, number of Si-OR: 3) 106
Production Example 5 100.0
(Carbon number: 200) 15.2
(Carbon number: 121.6) 0.4
(Carbon number: 2.8, number of Si-OR: 1.2) 270

Example  - for photovoltaic Encapsulant  Manufacture of sheet

Example  One

35 parts by weight of the silane master batch prepared separately in Production Example 1, 5 parts by weight of the additive master batch and 60 parts by weight of a polyethylene elastomer (LC670, manufactured by LG Chemical Co., Ltd.) as a base resin were stirred in a dumbbell for at least 30 minutes, Sheet was formed at a temperature of 180 DEG C by using a single extruder (RHOMEX 25, HAAHE Co.) having a width T-die attached thereto. The thickness of the sheet was adjusted to the sheet of 500 mu m by controlling the speed of the cooling roller for cooling the extrudate extruded from the T-die.

Example  2

An encapsulating material sheet was prepared in the same manner as in Example 1, except that 35 parts by weight of the masterbatch prepared in Production Example 2 was used as the silane master batch.

Example  3

A sealant sheet was prepared in the same manner as in Example 1, except that 35 parts by weight of the master batch prepared in Preparation Example 3 was used as the silane master batch.

Example  4

A sealant sheet was prepared in the same manner as in Example 1, except that 20 parts by weight of the master batch prepared in Preparation Example 1 was used as the silane master batch and the content of the base resin was 75 parts by weight.

Example  5

An encapsulating material sheet was prepared in the same manner as in Example 1, except that 50 parts by weight of the master batch prepared in Preparation Example 3 was used as the silane master batch and 45 parts by weight of the base resin was used.

Furtherance Example 1 Example 2 Example 3 Example 4 Example 5 Production Example 1 35 20 Production Example 2 35 Production Example 3 35 50 additive 5 5 5 5 5 Base resin 60 60 60 75 45 The number of carbon atoms per Si-O-R 591 326 180 1035 126

Example  6

An encapsulating material sheet was prepared in the same manner as in Example 1 except that 35 parts by weight of the masterbatch prepared in Production Example 4 was used as the silane master batch.

Example  7

A sealant sheet was prepared in the same manner as in Example 1, except that 35 parts by weight of the masterbatch prepared in Preparation Example 5 was used as the silane masterbatch.

Example  8

A sealant sheet was prepared in the same manner as in Example 1, except that 10 parts by weight of the master batch prepared in Preparation Example 4 was used as the silane master batch and the content of the base resin was 85 parts by weight.

Example  9

A sealant sheet was prepared in the same manner as in Example 1 except that 60 parts by weight of the masterbatch prepared in Production Example 5 was used as the silane master batch and the content of the base resin was used as 35 parts by weight.

Example  10

A sealant sheet was prepared in the same manner as in Example 1, except that 60 parts by weight of the masterbatch prepared in Preparation Example 4 was used as the silane master batch and the content of the base resin was 35 parts by weight.

Example  11

An encapsulating material sheet was prepared in the same manner as in Example 1, except that 95 parts by weight of the master batch prepared in Preparation Example 5 was used as the silane master batch and the base resin was not used.

Furtherance Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Production Example 4 35 10 60 Production Example 5 35 60 95 additive 5 5 5 5 5 Base resin 60 60 85 35 35 - The number of carbon atoms per Si-O-R 303 771 1060 450 177 284

Comparative Example  One

5 parts by weight of the silane master batch prepared separately in Production Example 1, 5 parts by weight of the additive master batch and 90 parts by weight of a polyethylene elastomer (LC670, manufactured by LG Chemical Co., Ltd.) as a base resin were stirred in a dumbbell for at least 30 minutes, Sheet was formed at a temperature of 180 DEG C by using a single extruder (RHOMEX 25, HAAHE Co.) having a width T-die attached thereto. The thickness of the sheet was adjusted to the sheet of 500 mu m by controlling the speed of the cooling roller for cooling the extrudate extruded from the T-die.

Comparative Example  2

An encapsulating material sheet was prepared in the same manner as in Example 1 except that the silane master batch was not used and the content of the base resin was 95 parts by weight.

Comparative Example  3

An encapsulating material sheet was prepared in the same manner as in Example 1, except that 95 parts by weight of the master batch prepared in Preparation Example 3 was used as the silane master batch and the base resin was not used.

Comparative Example  4

Except that 35 parts by weight of the masterbatch prepared in Production Example 2 was used as the silane master batch and 60 parts by weight of polyethylene elastomer (LC100 (density 0.903 g / cm ³ ), LG Chemical Co., Ltd.) 1 to prepare an encapsulating material sheet.

Furtherance Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Production Example 1 5 Production Example 2 35 Production Example 3 95 additive 5 5 5 5 Base resin
LC670 90 95 LC100 60 The number of carbon atoms per Si-O-R 4140 - 66 326

Reference example

For comparison of properties, RC02B of Mitsui Chemical Tocello Co., Ltd., which has been commercialized as a conventional ethylene-vinyl acetate copolymer resin (EVA) encapsulant, was used as a reference example.

The physical properties in the following examples and comparative examples were evaluated in the following manner.

1. Measurement of Adhesion

The encapsulating material sheets prepared in Examples 1 to 11 and Comparative Examples 1 to 4 were cut into a size of 100 mm x 100 mm and then heat-treated at 150 DEG C for 10 minutes using a vacuum laminator (LM-30 x 30-S, NPC) The specimens were prepared by lamination. The structure of the sample was laminated in the order of glass / encapsulation sheet 2 layers / back sheet. At this time, the glass used was LIF (Float) grade which is low iron glass of Nuri Corporation and LBF-CF which is a fluorine-based back sheet of LG Chem was used as the back sheet.

The adhesive strength was measured in accordance with ASTM D1897, while the specimen was cut to a width of 15 mm and then peeled off at a peel rate of 4.2 mm / sec and a peel angle of 180 °. To determine the long-term reliability, the samples were left in an oven maintained at 85 ° C and 85% relative humidity for 1,000 hours, and then the change in adhesion was examined.

2. Measurement of transmittance and haze

The encapsulating material sheets prepared in Examples 1 to 11 and Comparative Examples 1 to 4 were cut into a size of 100 mm x 100 mm and then heat-treated at 150 DEG C for 10 minutes using a vacuum laminator (LM-30 x 30-S, NPC) The specimens were prepared by lamination. The laminated specimens were measured for transmittance and haze using a hazemeter.

3. Moisture Barrier property  evaluation

The encapsulating material sheets prepared in Examples 1 to 11 and Comparative Examples 1 to 4 were cut into a size of 100 mm x 100 mm and then heat-treated at 150 DEG C for 10 minutes using a vacuum laminator (LM-30 x 30-S, NPC) The specimens were prepared by lamination. Water Vapor Permiablity Test (TSY-T3, Labthink) was used for water permeability measurement.

The laminated specimens were cut into a circular shape with a diameter of 8 cm, placed on a cup-shaped container filled with water, and weighed to see how much moisture permeated under conditions of relative humidity of 90%. A day was measured as a basic unit, and further experiments were conducted according to the results of the experiment.

Tables 6 to 8 show the results of measuring the physical properties of the samples used in Examples and Comparative Examples.

Properties Example 1 Example 2 Example 3 Example 4 Example 5 Glass / sealing material adhesive force (N / 15 mm), 0 hr 143 138 140 141 139 Glass / sealing material adhesive force (N / 15 mm), 1000 hr 150 225 225 182 205 Back sheet / sealant adhesive force (N / 15mm), 0hr 137 142 141 139 141 Back sheet / sealing material adhesive force (N / 15 mm), 1000 hr 202 277 252 204 250 Transmittance 91.3 91.4 91.1 91.4 90.6 Cloudiness 4.2 3.7 4.2 4.1 4.6 Moisture permeability 3.1 3.2 3.2 3.1 3.4

Properties Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Glass / sealing material adhesive force (N / 15 mm), 0 hr 141 129 120 139 127 130 Glass / sealing material adhesive force (N / 15 mm), 1000 hr 170 181 137 191 210 195 Back sheet / sealant adhesive force (N / 15mm), 0hr 127 131 119 137 135 129 Back sheet / sealing material adhesive force (N / 15 mm), 1000 hr 140 150 129 145 210 194 Transmittance 91.7 91.1 91.4 92.1 90.7 90.5 Cloudiness 3.4 3.7 3.5 4.1 5.1 5.3 Moisture permeability 3.0 3.1 3.4 3.3 3.2 3.4

Properties Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Reference example Glass / sealing material adhesive force (N / 15 mm), 0 hr 13 3 141 140 92 Glass / sealing material adhesive force (N / 15 mm), 1000 hr 19 0 191 183 111 Back sheet / sealant adhesive force (N / 15mm), 0hr 6 0 141 139 130 Back sheet / sealing material adhesive force (N / 15 mm), 1000 hr 4 0 184 178 136 Transmittance 91.1 90.5 89.1 89.7 92.5 Cloudiness 4.2 4.8 21.4 19.7 2.1 Moisture permeability 3.3 3.2 3.0 2.5 22.3

As can be seen from the above physical properties evaluation, the sealing material sheets of Examples 1 to 11 exhibited excellent characteristics in terms of adhesive force, light transmittance, fogging and water permeability. However, in the case of Comparative Examples 1 and 2, it can be confirmed that the alkoxysilane group is not sufficiently grafted or is not present, so that the adhesive strength is insufficient. In the case of Comparative Example 3, it was confirmed that the degree of fogging was increased because the alkoxysilane group was excessively large. As the amount of the grafted alkoxysilane increases, the degree of curing due to moisture increases during storage, which makes it difficult to store the sample. In the case of Comparative Example 4, the use of an alpha-olefin copolymer having a high density as the base resin of the sealing material sheet increases the degree of crystallization of the alpha-olefin, thereby deteriorating the fogging. As a result of checking the physical properties of the EVA encapsulant as a reference example, it can be confirmed that the moisture permeability of the encapsulant sheet according to the above embodiments is much better than that of the EVA encapsulant. This leads to an improvement in the reliability of the photovoltaic module under high temperature and wet conditions.

1: glass
2: Sealing sheet
3: back sheet

Claims (14)

(a) an ethylene-alpha olefin copolymer and (b) a silane graft-modified ethylene-alpha olefin copolymer, wherein the sealing material sheet comprises an ethylene-alpha olefin copolymer (a) An encapsulant sheet having a number of grafted alkoxysilane groups in the entire ethylene-alpha olefin copolymer including a graft-modified ethylene-alpha olefin copolymer, wherein the number of grafted alkoxysilane groups is one per 100 to 4,000 carbon atoms. The method according to claim 1, wherein the alpha olefin of the ethylene-alpha olefin copolymer is selected from the group consisting of propylene, 1-butene, isobutylene, 2-methyl-1-butene, Hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, Norbornene, norbornene, ethylidenenorbornene, phenyl norbornene, vinyl norbornene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, alpha-methyl Styrene, divinylbenzene, and 3-chloromethylstyrene. The encapsulating sheet according to claim 1, wherein the ethylene-alpha olefin copolymer (a) and the ethylene-alpha olefin copolymer (b) silane graft-modified ethylene-alpha olefin copolymer are the same. The encapsulating material sheet according to claim 1, wherein the ethylene-alpha olefin copolymer (a) and the ethylene-alpha olefin copolymer (b) silane graft-modified ethylene-alpha olefin copolymer are different. The sealant sheet according to claim 1, wherein the ethylene-alpha olefin copolymer (a) has a density of 0.85 to 0.89 g / cm ³ . The sealant sheet according to claim 1, wherein the silane graft-modified ethylene-alpha olefin copolymer (b) has a density of 0.85 to 0.89 g / cm ³ . The sealant sheet according to claim 1, wherein the silane graft-modified ethylene-alpha olefin copolymer (b) is obtained by grafting an alkoxysilane-based compound onto an ethylene-alpha olefin copolymer. 8. The sealant sheet according to claim 7, wherein the alkoxysilane compound comprises a double bond capable of radical graft polymerization. The method according to claim 7, wherein the alkoxysilane compound is selected from the group consisting of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane, vinyl Vinyltriethoxysilane, vinyltrialkoxysilane, vinyltris ([beta] -methoxy) silane, vinyltriethoxysilane, vinyltriethoxysilane, vinyltriethoxysilane, vinyltriethoxysilane, Allyltripropoxysilane, allyltriphenoxysilane, allyltriboxysilane, allyltripropoxysilane, allyltriethoxysilane, allyltriethoxysilane, allyltriethoxysilane, allyltriethoxysilane, allyltriethoxysilane, But are not limited to, oxysilane, allyltrimethylene dioxy silane, allyltriethylenedioxysilane, allylpropionyloxysilane, allyltriacetoxysilane, allyltricarboxysilane, allyltris (? -Methoxyethoxysil Methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, and γ-methacryloxypropylmethyldiethoxysilane. An encapsulant sheet comprising at least one selected. The sealing material sheet according to claim 1, wherein the sealing material sheet further comprises at least one member selected from the group consisting of an ultraviolet absorber, a light stabilizer, a heat stabilizer, an antioxidant, and a moisture absorbent. The sealing material sheet according to claim 1, wherein the sealing material sheet has a thickness of 0.1 to 1 mm. The sealing material sheet according to claim 1, wherein the sealing material sheet has a light transmittance of 91% or more and a water permeation amount of 1.0 to 5.0 g / m ² · 1day. preparing a resin composition comprising (a) an ethylene-alpha olefin copolymer and (b) a silane graft-modified ethylene-alpha olefin copolymer,
And a step of processing the resin composition into a sheet. 14. The method of claim 13, wherein (a) an ^{ethylene-alpha-3} and the olefin copolymer a density of 0.85 to 0.89 g / cm, the molecular weight distribution (Mw / Mn) of less than 3.5 The method of the encapsulant sheet.

Images