Monomer composition containing unsaturated polyalkylene glycol ether-based monomer, method for producing composition thereof, polymer obtained using composition thereof, and method for producing polymer thereof

A method for producing a polycarboxylic acid-based polymer, the method comprising:

• a reaction step for reacting alkenyl alcohol with alkylene oxide having 2 to 18 carbon atoms in the presence of an alkali catalyst to give an unsaturated polyalkylene glycol ether-based monomer, said alkenyl alcohol selected from the group consisting of 3-methyl-3-buten-1-ol (CH2═C(CH3)—CH2CH2—OH), 2-methyl-3-buten-1-ol (CH2═CHCH(CH3)—CH2—OH), 5-hexen-1-ol (CH2═CHCH2CH2CH2CH2—OH), and 3-hepten-1-ol (CH3CH2CH2CH═CHCH2CH2—OH);
• a concentration adjustment step for adding water to the reaction liquid obtained from the reaction step to yield an aqueous solution;
• a neutralization step for neutralizing the reaction liquid obtained from the reaction step to pH 4 to pH 13 by using an organic acid, wherein the organic acid is a hydrocarbon having 1 to 10 carbon atoms and has a carboxy group or a sulfo group;
• and
• a polymerization step for obtaining the polycarboxylic acid-based polymer by using the monomer composition obtained after the neutralization step and reacting the unsaturated polyalkylene glycol ether-based monomer contained in the monomer composition with the unsaturated acid-based monomer represented by the following chemical formula (2):
• [in the formula,
• R3, R4, and R5 each independently represent a hydrogen atom, a methyl group, or a —(CH2)pCOOH group (here, p is an integer of from 0 to 2);
• and
• M represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group].