Binder for non-aqueous secondary battery, composition for non-aqueous secondary battery functional layer, functional layer for non-aqueous secondary battery, and non-aqueous secondary battery
Provided is a binder for a non-aqueous secondary battery that has excellent preservation stability and binding capacity, and that can suppress viscosity elevation of a slurry composition. The binder for a non-aqueous secondary battery contains a particulate polymer and water. The particulate polymer has a degree of swelling in an aqueous medium at pH 5 of less than a factor of 2 and has a degree of swelling in an aqueous medium at pH 8 of at least a factor of 2 and no greater than a factor of 7.
1. A binder for a non-aqueous secondary battery, comprising
a particulate polymer and water, wherein
the particulate polymer has a degree of swelling in an aqueous medium at pH 5 of less than a factor of 2,
the particulate polymer has a degree of swelling in an aqueous medium at pH 8 of at least a factor of 2 and no greater than a factor of 7, and
the particulate polymer includes at least 17 mass % of an acid group-containing monomer unit.
2. The binder for a non-aqueous secondary battery of claim 1 , wherein
the particulate polymer includes at least 17 mass % and no greater than 30 mass % of the acid group-containing monomer unit.
3. The binder for a non-aqueous secondary battery of claim 1 , wherein
the particulate polymer includes either or both an aliphatic conjugated diene monomer unit and an aromatic vinyl monomer unit, and
a percentage content of the aliphatic conjugated diene monomer unit and a percentage content of the aromatic vinyl monomer unit are, in total, at least 10 mass % and no greater than 80 mass %.
4. The binder for a non-aqueous secondary battery of claim 1 , wherein
the particulate polymer includes at least 10 mass % and no greater than 60 mass % of an aliphatic conjugated diene monomer unit.
5. The binder for a non-aqueous secondary battery of claim 1 , wherein
the particulate polymer includes at least 10 mass % and no greater than 60 mass % of an aromatic vinyl monomer unit.
6. A composition for a non-aqueous secondary battery functional layer, comprising:
the binder for a non-aqueous secondary battery of claim 1 ; and non-conductive particles, wherein
the composition for a non-aqueous secondary battery functional layer has a pH of higher than 7.
7. A functional layer for a non-aqueous secondary battery formed using the composition for a non-aqueous secondary battery functional layer of claim 6 .
8. A non-aqueous secondary battery comprising the functional layer for a non-aqueous secondary battery of claim 7 .
9. The binder for a non-aqueous secondary battery of claim 1 , wherein
the particulate polymer includes at least 20 mass % of the acid group-containing monomer unit.
10. The binder for a non-aqueous secondary battery of claim 1 , wherein
the acid group-containing monomer unit is a structural unit derived from a carboxylic acid group-containing monomer.