Liquid dispersant composition for gypsum

A method for producing a gypsum slurry having pH of 6.0 or more and 9.0 or less at 20° C., comprising the following steps:

• step 1:
• a step of mixing a component (A), a component (B), and water to provide a liquid composition for preparing gypsum;
• and
• step 2:
• a step of mixing the liquid composition for preparing gypsum obtained in the step 1 and gypsum to provide a gypsum slurry,
• the component (A) being a copolymer obtained through polymerization of a monomer containing a monomer (A1) represented by the following general formula (A1) and a monomer (A2) represented by the following general formula (A2), and the component (B) being a nitrogen-containing compound,
• in the component (A), a ratio of a mass of the monomer (A2) with respect to a total mass of the monomer (A1) and the monomer (A2) being 4% by mass or more,
• the component (B) being one or more kinds of a nitrogen-containing compound selected from ammonia, an alkylamine, an alkanolamine, an alkylalkanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and a polyethyleneimine,
• the alkylamine as the component (B) being an alkylamine selected from a primary amine having an alkyl group having 5 or less in total carbon atoms, a secondary amine having alkyl groups having 6 or less in total carbon atoms, and a tertiary amine having alkyl groups having 5 or less in total carbon atoms,
• the alkanolamine as the component (B) being an alkanolamine having 1 or more and 10 or less carbon atoms and having 1 or more and 3 or less alkanol groups, and
• the alkylalkanolamine as the component (B) being an alkylalkanolamine having 2 or more and 10 or less carbon atoms and having 1 or 2 alkyl groups:
• wherein
• R1 and R2 each independently represent a hydrogen atom or a methyl group;
• m1 represents an integer of 0 or more and 2 or less;
• AO represents an alkyleneoxy group having 2 or 3 carbon atoms;
• n represents an average addition molar number of AO, which is a number of 4 or more and 300 or less;
• and
• X represents a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms,
• wherein
• R3, R4 and R5 each independently represent a hydrogen atom, a methyl group, or (CH2)m2COOM2;
• M1 and M2 each independently represent a hydrogen atom, an alkali metal, an alkaline earth metal (½ atom), an organic ammonium group, or an ammonium group;
• and
• m2 represents an integer of 0 or more and 2 or less.

A method for producing a liquid dispersant composition for gypsum, comprising mixing (A) a copolymer (hereinafter referred to as a component (B)) obtained through polymerization of a monomer containing a monomer (A1) represented by the following general formula (A1) and a monomer (A2) represented by the following general formula (A2) (hereinafter referred to as a component (A)), (B) a nitrogen-containing compound, and water,

• in the component (A), a ratio of a mass of the monomer (A2) with respect to a total mass of the monomer (A1) and the monomer (A2) being 4% by mass or more,
• the component (B) being one or more kinds of a nitrogen-containing compound selected from ammonia, an alkylamine, an alkanolamine, an alkylalkanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and a polyethyleneimine,
• the alkylamine as the component (B) being an alkylamine selected from a primary amine having an alkyl group having 5 or less carbon atoms in total, a secondary amine having alkyl groups having 6 or less carbon atoms in total, and a tertiary amine having alkyl groups having 5 or less carbon atoms in total,
• the alkanolamine as the component (B) being an alkanolamine having 1 or more and 10 or less carbon atoms and having 1 or more and 3 or less alkanol groups,
• the alkylalkanolamine as the component (B) being an alkylalkanolamine having 2 or more and 10 or less carbon atoms and having 1 or 2 alkyl groups, and
• the liquid dispersant composition for gypsum having pH of 7.0 or more and 13.0 or less at 20° C.:
• wherein
• R1 and R2 each independently represent a hydrogen atom or a methyl group;
• m1 represents an integer of 0 or more and 2 or less;
• AO represents an alkyleneoxy group having 2 or 3 carbon atoms;
• n represents an average addition molar number of AO, which is a number of 4 or more and 300 or less;
• and
• X represents a hydrogen atom or an alkyl group having 1 or more and 3 or less carbon atoms,
• wherein
• R3, R4 and R5 each independently represent a hydrogen atom, a methyl group, or (CH2)m2COOM2;
• M1 and M2 each independently represent a hydrogen atom, an alkali metal, an alkaline earth metal (½ atom), an organic ammonium group, or an ammonium group;
• and
• m2 represents an integer of 0 or more and 2 or less.