Encapsulating Material for Solar Cell

Abstract

Encapsulating material for solar cells which facilitates fabricating solar cell modules and has excellent transparency, heat resistance, flexibility, etc., and a solar cell modules. More specifically, the present invention provides encapsulating material for solar cells comprising a non-crystalline or low-crystalline a-olefin-based copolymer or its composition (I). In a preferred embodiment, the aforementioned copolymer or its composition (I) is a resin composition (C) containing 50 to 100 parts by weight of non-crystalline α-olefin polymer (A) meeting the following requirements: (a) the α-olefin having 3 to 20 carbon atoms is not less than 20 mol %, (b) practically no melt peak as measured by a differential scanning calorimeter is observed, and (c) the Mw/Mn is not more than 5, and 50 to 0 parts by weight of crystalline α-olefin polymer (B) (the total of (A) and (B) being 100 parts by weight).

1 . Encapsulating material for solar cells comprising a non-crystalline or low-crystalline α-olefin-based copolymer or its composition (I).  
     
     
         2 . Encapsulating material for solar cells according to  claim 1 , wherein the aforementioned non-crystalline or low-crystalline α-olefin-based copolymer or its composition (I) is resin composition (C) containing 50 to 100 parts by weight of non-crystalline α-olefin polymer (A) meeting the following requirements (a) through (c) and 50 to 0 parts by weight of crystalline α-olefin polymer (B) (the total of (A) and (B) being 100 parts by weight): 
 (a) a polymerization unit based on α-olefin having 3 to 20 carbon atoms is not less than 20 mol %;    (b) practically no melt peak as measured by a differential scanning calorimeter is observed;    (c) the Mw/Mn is not more than 5.    
     
     
         3 . Encapsulating material for solar cells according to  claim 2 , wherein the propylene polymerization unit of the aforementioned non-crystalline α-olefin polymer (A) is not less than 30 mol %.  
     
     
         4 . Encapsulating material for solar cells according to  claim 2 , wherein the aforementioned non-crystalline α-olefin polymer (A) is a polymer produced by use of a metallocene catalyst.  
     
     
         5 . Encapsulating material for solar cells according to  claim 2 , wherein the aforementioned crystalline α-olefin polymer (B) is a propylene homopolymer or a copolymer of propylene and another α-olefin.  
     
     
         6 . Encapsulating material for solar cells according to  claim 2 , wherein the aforementioned resin composition (C) is a composition having JIS A hardness of 40 to 100.  
     
     
         7 . Encapsulating material for solar cells according to  claim 1 , wherein the aforementioned copolymer or its composition (I) is a non-crystalline or low-crystalline α-olefin copolymer (D) having a crystallinity of not higher than 40% as measured by use of X rays.  
     
     
         8 . Encapsulating material for solar cells according to  claim 7 , wherein the Shore D hardness of the aforementioned non-crystalline or low-crystalline α-olefin-based copolymer is not higher than 60.  
     
     
         9 . Encapsulating material for solar cells according to  claim 1 , wherein at least one kind selected from among cross-linking agents, cross-linking accelerators, silane-coupling agents, antioxidants, ultraviolet absorbers and light stabilizers is compounded to the aforementioned copolymer or its composition (I).  
     
     
         10 . Encapsulating material for solar cells according to  claim 1 , wherein the storage elastic modulus at 150° C. of the aforementioned copolymer or its composition (I) is not lower than 10 3  Pa.  
     
     
         11 . Encapsulating material for solar cells according to  claim 1 , wherein the haze of the aforementioned copolymer or its composition (I) at the thickness of 0.5 mm is not higher than 10%.  
     
     
         12 . Encapsulating material for solar cells according to  claim 1 , which is in the form of sheet.  
     
     
         13 . A solar cell module which is obtained by using the solar cell encapsulating material as defined in  claim 1 .  
     
     
         14 . A solar cell module according to  claim 13 , wherein the solar cell encapsulating material layer is cross-linked.  
     
     
         15 . Encapsulating material for solar cells according to  claim 2 , wherein the storage elastic modulus at 150° C. of the aforementioned copolymer or its composition (I) is not lower than 10 3  Pa.  
     
     
         16 . Encapsulating material for solar cells according to  claim 2 , wherein the haze of the aforementioned copolymer or its composition (I) at the thickness of 0.5 mm is not higher than 10%.