Binder polymer for nonaqueous secondary batteries, binder composition for nonaqueous secondary batteries, and nonaqueous secondary battery electrode

A binder polymer for nonaqueous secondary batteries,

• wherein, when a water dispersion having a pH of 12.0 at 23° C., which contains the binder polymer for nonaqueous secondary batteries at a solid content concentration of 8.0 mass %, is prepared and a 1.0 mol/L hydrochloric acid aqueous solution is added to 125 g of the water dispersion at a rate of 0.5 mL/30 seconds, there are only two linear functions, a first straight line L1 and a second straight line L2, which are determined through a least-squares method from a relationship between an electrical conductivity of y S/m of the water dispersion and a cumulative addition amount of x mL of the hydrochloric acid aqueous solution from the start of addition of the hydrochloric acid aqueous solution and until the electrical conductivity of the water dispersion reaches 2.0 S/m,
• the first straight line L1 is represented by Formula (1) below, and
• the second straight line L2 is represented by Formula (2) below,
• y
• =
• a
• 1
• ⁢
• x
• +
• b
• 1
• (
• 1
• )
• (in Equation (1), a1 and b1 are greater than 0), and
• y
• =
• a
• 2
• ⁢
• x
• +
• b
• 2
• (
• 2
• )
• (in Equation (2), a2 is greater than a1).