Dark type fluororesin film and back sheet for solar cell module
View Patent ↗A fluororesin film usable as the outermost layer of a back sheet for a solar cell module, which is a dark type fluororesin film having a sufficient electric insulation property and weather resistance, and which is particularly excellent in thermal resistance; and a back sheet for a solar cell module employing such a film, which dark type fluororesin film, which is a fluororesin film contains an ethylene-tetrafluoroethylene copolymer as the main component and contains from 1.0 to 4.5 parts by mass of a carbon black having a pH of from 8 to 10 as measured according to JIS K6221 section 6.4.2 based on 100 parts by mass of the ethylene-tetrafluoroethylene copolymer.
1. A fluororesin film, which comprises an ethylene-tetrafluoroethylene copolymer as the main component and contains from 1.0 to 4.5 parts by mass of a carbon black having a pH of from 8 to 10 as measured according to JIS K6221 section 6.4.2 based on 100 parts by mass of the ethylene-tetrafluoroethylene copolymer, which fluororesin film has a volume resistivity of at least 1×10 13 Ω·cm,
wherein the fluororesin film has a thickness of from 12 to 100 μm.
2. The fluororesin film according to claim 1 , wherein the carbon black has a specific surface area of from 30 to 150 m 2 /g in terms of nitrogen adsorption as measured according to JIS K6217.
3. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 wherein the carbon black is an acetylene black or a furnace black.
4. A solar cell module comprising the back sheet as defined in claim 3 .
5. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 , wherein the fluororesin film further contains a copper compound in an amount of from 1×10 −4 to 5×10 −2 parts by mass based on 100 parts by mass of the ethylene-tetrafluoroethylene copolymer.
6. The back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 5 , wherein the copper compound is present in an amount of 10 to 200 ppm by mass based on 100 parts by mass of the ethylene-tetrafluoroethylene copolymer.
7. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 , wherein the fluororesin film has a transmittance of less than 1% for UV rays having a wavelength of 360 nm or shorter.
8. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 as the outermost layer of the back sheet.
9. The back sheet for a solar cell module according to claim 8 , wherein the laminate comprises the fluororesin film, an adhesive layer and a moisture-proof layer laminated in this order.
10. The back sheet for a solar cell module according to claim 8 , wherein the laminate comprises the fluororesin film, an adhesive layer, a moisture-proof layer and a fluororesin film laminated in this order.
11. The back sheet for a solar cell module according to claim 8 , wherein the fluororesin film has a thickness of from 20 to 50 μm.
12. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 , wherein the ethylene-tetrafluoroethylene copolymer is the only resin component of the fluororesin film.
13. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 , wherein the amount of carbon black is from 1.5 to 3.0 parts by mass.
14. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 , wherein the fluororesin film has a transmittance of at most 0.1% for UV rays having a wavelength of 360 nm or shorter.
15. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 , wherein the volume resistivity is at least 1×10 14 Ω·cm.
16. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 , wherein the pH is from 9 to 10.
17. A back sheet for a solar cell module comprising a laminate having the fluororesin film as defined in claim 1 , wherein the carbon black has a specific surface area of from 40 to 135 m 2 /g in terms of nitrogen adsorption as measured according to JIS K6217.