PROBLEM TO BE SOLVED: To provide a new type of paper strength agent which is less affected by ionic impurities and has an excellent paper strength enhancing effect by solving the problem of a commonly used amphoteric type paper strength agent. SOLUTION: A polymer obtained by polymerizing a monomer component containing a reactive surfactant, (meth) acrylamide and a cationic monomer as essential components and not containing a hydrophobic monomer is excellent. Demonstrates the effect of increasing paper strength. It is preferable that the polymer is a polymer obtained by polymerizing a monomer component in which the reactive surfactant is 0.1 to 15% by mass with respect to all the monomers. [Selection diagram] None
展开▼
