Liquid absorbing sheet and nonaqueous electrolyte battery pack

Abstract

A liquid absorbing sheet has a liquid-absorbing resin layer that can effectively absorb the nonaqueous electrolyte solution used in nonaqueous electrolyte secondary cells that make nonaqueous electrolyte battery packs (in particular, lithium ion-based nonaqueous secondary battery packs). The liquid-absorbing resin layer is obtained by irradiating a particular monomer composition with UV rays or other energy rays to polymerize the monomer composition. The monomer composition contains a monofunctional monomer component (A) having a polyethylene glycol acrylate monomer and an amide bond-containing acrylic monomer; and a polyfunctional monomer component (B).

1 . A liquid absorbing sheet for absorbing a nonaqueous electrolyte solution, comprising:
 a liquid-absorbing resin layer capable of absorbing a nonaqueous electrolyte solution and shows adhesion, wherein the liquid-absorbing resin layer comprises a polymer of a monomer composition, the monomer composition containing:
 a monofunctional monomer component (A) comprising a polyethylene glycol acrylate monomer and an amide bond-containing acrylic monomer; and 
 a polyfunctional monomer component (B). 
   
     
     
         2 . The liquid absorbing sheet according to  claim 1 , wherein the polyethylene glycol acrylate monomer is phenoxypolyethylene glycol acrylate or methoxypolyethylene glycol acrylate. 
     
     
         3 . The liquid absorbing sheet according to  claim 1 , wherein the amide bond-containing acrylic monomer is acryloylmorpholine or N,N-diethylacrylamide. 
     
     
         4 . The liquid absorbing sheet according to  claim 1 , wherein the liquid-absorbing resin layer is formed over a substrate. 
     
     
         5 . The liquid absorbing sheet according to  claim 4 , wherein the substrate is capable of absorbing and retaining a nonaqueous electrolyte solution. 
     
     
         6 . The liquid absorbing sheet according to  claim 2 , wherein the liquid-absorbing resin layer is formed over a substrate. 
     
     
         7 . The liquid absorbing sheet according to  claim 3 , wherein the liquid-absorbing resin layer is formed over a substrate. 
     
     
         8 . The liquid absorbing sheet according to  claim 1 , wherein the nonaqueous electrolyte solution contains carbonates. 
     
     
         9 . The liquid absorbing sheet according to  claim 1 , wherein in the monofunctional monomer composition (A), the amount of the amide bond-containing acrylic cycle is in the range of 20 to 70 parts by weight with respect to 100 parts by weight of the polyethylene glycol acrylic monomer. 
     
     
         10 . The liquid absorbing sheet according to  claim 1 , wherein the polyfunctional monomer composition (B) is added to the monomer composition in an amount to give a crosslink density of about 0.0001 to 0.17.