# US 8,772,625 B2 · Encapsulating material for solar cell and solar cell module

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- Number: US 8,772,625 B2
- Document ID: US8772625B2
- Status: Granted
- Kind: B2
- Application number: 13/820,941
- Filed: 2011-10-07
- Published: 2013-07-04
- Granted: 2014-07-08
- Earliest claimed: 2010-10-08
- Assignees: Mitsui Chemicals, Inc.; Mitsui Chemicals Tohcello, Inc.
- Applicants: Shigenobu Ikenaga; Fumito Takeuchi; Keiji Watanabe; Jun Tokuhiro; Takanobu Murofushi; Kazuhiro Yarimizu; Tomoaki Ito; Nobuhiro Maruko
- Inventors: Shigenobu Ikenaga; Fumito Takeuchi; Keiji Watanabe; Jun Tokuhiro; Takanobu Murofushi; Kazuhiro Yarimizu; Tomoaki Ito; Nobuhiro Maruko
- Web page: https://patentgrep.com/patent/US8772625B2

## CPC

- H10F 19/804: {Materials of encapsulations}
- C09D 123/0815: {Copolymers of ethene with aliphatic 1-olefins}
- C09K 3/10: {Materials in mouldable or extrudable form} for sealing or packing joints or covers (filling pastes C09D5/34)
- C08F 4/65908: {in combination with an ionising compound other than alumoxane, e.g. (C6F5)4B-X+}
- C08F 4/65912: {in combination with an organoaluminium compound}
- C08F 4/6592: containing at least one cyclopentadienyl ring, condensed or not, e.g. an indenyl or a fluorenyl ring
- C08F 4/65925: {two cyclopentadienyl rings being mutually non-bridged}
- C08L 2312/08: by silane
- C09K 2200/0617: Polyalkenes
- C09K 2200/062: Polyethylene
- Y02B 10/10: Photovoltaic [PV]
- Y02E 10/50: Photovoltaic [PV] energy
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Disclosed is an encapsulating material for solar cell containing an ethylene/α-olefin copolymer satisfying the following requirements (a1) to (a4): (a1) the content ratio of structural units derived from ethylene is from 80 to 90 mol % and the content ratio of structural units derived from α-olefin having 3 to 20 carbon atoms is from 10 to 20 mol %; (a2) MFR is from 10 to 50 g/10 minutes as measured under the conditions of a temperature of 190 degrees centigrade and a load of 2.16 kg in accordance with ASTM D1238; (a3) the density is from 0.865 to 0.884 g/cm3 as measured in accordance with ASTM D1505; and (a4) the shore A hardness is from 60 to 85 as measured in accordance with ASTM D2240.

## Claims

### Claim 1

An encapsulating material for solar cell comprising an ethylene/α-olefin copolymer satisfying the following requirements (a1) to (a4) and (a6):
(a1) the content ratio of structural units derived from ethylene is from 80 to 90 mol % and the content ratio of structural units derived from α-olefin having 3 to 20 carbon atoms is from 10 to 20 mol %;
(a2) MFR is from 10 to 50 g/10 minutes as measured under the conditions of a temperature of 190 degrees centigrade and a load of 2.16 kg in accordance with ASTM D1238;
(a3) the density is from 0.865 to 0.884 g/cm3 as measured in accordance with ASTM D1505;
(a4) the shore A hardness is from 60 to 85 as measured in accordance with ASTM D2240; and
(a6) the content of aluminum element in said ethylene/α-olefin copolymer is from 10 to 500 ppm.

### Claim 2 (depends on 1)

The encapsulating material for solar cell according to claim 1, wherein the encapsulating material for solar cell further satisfies the following requirement (a5):
(a5) the volume resistivity is from 1.0×1013 to 1.0×1018 Ω·cm as measured at a temperature of 100 degrees centigrade with an applied voltage of 500V in accordance with JIS K6911.

### Claim 3 (depends on 1)

The encapsulating material for solar cell according to claim 1, wherein MFR of said ethylene/α-olefin copolymer is from 10 to 27 g/10 minutes as measured under the conditions of a temperature of 190 degrees centigrade and a load of 2.16 kg in accordance with ASTM D1238.

### Claim 4 (depends on 1)

The encapsulating material for solar cell according to claim 1, wherein organic peroxide having a one-minute half-life temperature in the range of 100 to 170 degrees centigrade is further contained in an amount of 0.005 to 5 weight parts, based on 100 weight parts of said ethylene/α-olefin copolymer.

### Claim 5 (depends on 1)

The encapsulating material for solar cell according to claim 1, wherein said ethylene/α-olefin copolymer is polymerized in the presence of a catalyst for olefin polymerization comprising a metallocene compound, and at least one compound selected from the group consisting of an organic aluminumoxy compound and an organic aluminum compound.

### Claim 6 (depends on 1)

The encapsulating material for solar cell according to claim 1, comprising an ethylene resin composition containing a silane coupling agent in an amount of 0.1 to 5 weight parts and a crosslinking agent in an amount of 0.1 to 3 weight parts, based on 100 weight parts of said ethylene/α-olefin copolymer.

### Claim 7 (depends on 6)

The encapsulating material for solar cell according to claim 6, wherein said ethylene resin composition further comprises at least one kind selected from the group consisting of an ultraviolet absorber, a heat-resistant stabilizer and a hindered amine type light stabilizer in an amount of 0.005 to 5 weight parts, based on 100 weight parts of said ethylene/α-olefin copolymer.

### Claim 8 (depends on 6)

The encapsulating material for solar cell according to claim 6, wherein said ethylene resin composition further comprises a crosslinking aid in an amount of 0.05 to 5 weight parts, based on 100 weight parts of said ethylene/α-olefin copolymer.

### Claim 9 (depends on 1)

The encapsulating material for solar cell according to claim 1, obtained by melt-kneading said ethylene/α-olefin copolymer and an additive, and then extrusion-molding the melt-kneaded mixture in a sheet form.

### Claim 10 (depends on 1)

The encapsulating material for solar cell according to claim 1, wherein, for said ethylene/α-olefin copolymer, (a7) the B value determined from the 13C-NMR spectrum and the following equation (1) is from 0.9 to 1.5, and
(a8) the intensity ratio of Tαβ Tαα (Tαβ/Tαα) in the 13C-NMR spectrum is equal to or less than 1.5:
B Value=[POE]/(2×[PO]×[PE]) (1)
wherein, in the equation (1), [PE] represents the molar fraction of structural units derived from ethylene contained in said ethylene/α-olefin copolymer; [P0] represents the molar fraction of structural units derived from α-olefin having 3 to 20 carbon atoms contained in said ethylene/α-olefin copolymer; and [POE] represents the molar fraction of an α-olefin/ethylene chain contained in the total dyad chain.

### Claim 11 (depends on 1)

The encapsulating material for solar cell according to claim 1, wherein (a9) the molecular weight distribution (Mw/Mn) of said ethylene/α-olefin copolymer is in the range of 1.2 to 3.5 as measured by gel permeation chromatography (GPC).

### Claim 12 (depends on 1)

The encapsulating material for solar cell according to claim 1, wherein (a10) the content ratio of chlorine ion of said ethylene/α-olefin copolymer is equal to or less than 2 ppm as detected from an extract subjected to solid-phase extraction by ion chromatography.

### Claim 13 (depends on 1)

The encapsulating material for solar cell according to claim 1, wherein (a11) the extracted amount of said ethylene/α-olefin copolymer in methyl acetate is equal to or less than 5.0 weight %.

### Claim 14 (depends on 1)

The encapsulating material for solar cell according to claim 1, wherein the material is in a sheet form.

### Claim 15 (depends on 1)

A solar cell module comprising:
a transparent surface protective member;
a back surface protective member;
a solar cell element; and
an encapsulating layer for encapsulating said solar cell element between said transparent surface protective member and said back surface protective member to be formed by crosslinking said encapsulating material for solar cell according to claim 1.