Patent ID: 7247662

Claim:
A process for producing a cement dispersant, which is a process for producing a cement dispersant including a water-soluble polymer (P) as a main component, with the process comprising the step of polymerizing a monomer component to produce the water-soluble polymer (P) by polymerization, in the presence of a chain transfer agent, wherein the step of polymerizing includes the steps of: a step of polymerizing a monomer part (M1) of the monomer component, thereby producing polymer units (P1) constituting 60 to 99 mass % of the water-soluble polymer (P), wherein said step of producing polymer units (P1) is carried out by using a fraction (F1) of the chain transfer agent, wherein said fraction (F1) is not less than 80 mass % of the total amount of the chain transfer agent; and a step of polymerizing a monomer part (M2) of the monomer component, thereby producing polymer units (P2) constituting 1 to 40 mass % of the water-soluble polymer (P), wherein said step of producing polymer units (P2) is carried out by using a fraction (F2) of the chain transfer agent, wherein polymer units (P2) have a higher weight-average molecular weight than polymer units (P1), wherein the step of producing polymer units (P2) is carried out before the step of producing polymer units (P1), and wherein the step of producing polymer units (P2) is carried out by beforehand charging a reactor with the fraction (F2) of the chain transfer agent and no monomer part (M2), and after the reactor is charged, incrementally adding over a period of time the monomer part (M2) to the reactor.