Clay-containing gypsum slurry

Abstract

Provided is a clay-containing gypsum slurry that uses gypsum that includes clay but still has excellent water reduction properties, suppresses delays in setting time, and, when the gypsum slurry includes bubbles, produces a hardened gypsum body that has large-diameter bubbles.　A clay-containing gypsum slurry according to the present invention contains component (A), gypsum that includes clay, and water.　Component (A): A copolymer that includes, as structural monomers, a specific structural monomer (A1) represented by general formula (A1) and a specific structural monomer (A2) represented by general formula (A2), the structural monomer (A1) fraction of the total amount of the structural monomer (A1) and the structural monomer (A2) being less than 5 mass%, and the weight average molecular weight of the copolymer being 50,000–250,000.

Description

Clay-containing gypsum slurry

[0001] The present invention relates to a dispersant for a clay-containing gypsum slurry and a clay-containing gypsum slurry.

[0002] BACKGROUND ART Naphthalenesulfonic acid formaldehyde condensates have been used as dispersants in gypsum slurries used in gypsum boards. In recent years, the use of polycarboxylic acid-based dispersants has been increasing in order to reduce production costs. When manufacturing gypsum boards, the gypsum slurry is formed into a board and then dried in a dryer to remove excess water. However, the use of a highly water-reducing polycarboxylic acid-based dispersant allows the board to be formed with a small amount of water, which has the advantage of reducing drying costs. LPG, LNG, coal, petroleum, etc. are used as fuel for dryers, but the recent rise in fuel prices has led to an increase in the benefits of using polycarboxylic acid-based dispersants.

[0003] Japanese Patent Application Laid-Open No. 2022-018729 discloses a dispersant for a clay-containing hydraulic composition, which contains components (A), (B), and (C) made of specific polycarboxylic acid polymers different from one another, and in which the ratio of the total content of components (B) and (C) to the total content of components (A), (B), and (C) is 5% by mass or more and 20% by mass or less, and which can impart excellent fluidity to the hydraulic composition even when an aggregate containing clay is used.

[0004] Summary of the Invention Examples of gypsum used in gypsum slurries include natural gypsum and by-product gypsum such as flue gas desulfurization gypsum, and in recent years, inexpensive natural gypsum has become more common. However, natural gypsum contains clay and varies in quality. The inventors have discovered that when natural gypsum and a polycarboxylic acid dispersant are used in a gypsum slurry, the water-reducing properties of the gypsum slurry are significantly reduced, preventing the benefit of reducing drying costs by enabling molding with a small amount of water. The inventors have also discovered that increasing the amount of polycarboxylic acid dispersant used to improve the water-reducing properties of the gypsum slurry slows the coagulation of the gypsum slurry and reduces productivity. Furthermore, the inventors have discovered that when the gypsum slurry contains air bubbles, the polycarboxylic acid dispersant has the property of stabilizing the air bubbles. Therefore, if a large amount is used, the air bubbles in the gypsum slurry do not break down or coalesce, resulting in a small bubble diameter after the gypsum slurry hardens, resulting in a decrease in the strength of the gypsum hardened body.

[0005] The present invention provides a dispersant for clay-containing gypsum slurries that can impart excellent water reducing properties to gypsum slurry, suppress delays in setting time, and increase the air bubble diameter in the gypsum hardened body when the gypsum slurry contains air bubbles, even when gypsum containing clay is used; and provides a clay-containing gypsum slurry that has excellent water reducing properties, suppresses delays in setting time, and increases the air bubble diameter in the gypsum hardened body when the gypsum slurry contains air bubbles, even when gypsum containing clay is used.

[0006] The present invention relates to a dispersant for clay-containing gypsum slurries, which contains the following component (A): Component (A): a copolymer containing, as constituent monomers, a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2), in which the proportion of constituent monomer (A1) in the total amount of constituent monomer (A1) and constituent monomer (A2) is less than 5 mass % and the copolymer has a weight average molecular weight of 50,000 or more and 250,000 or less.

[0007]

[0008] [In the formula, R １ａ , R ２ａ , R ３ａ: the same or different, a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ａ and (CH ２ ) ｒ COOM ２ａ is COOM １ａ or other (CH ２ ) ｒ COOM ２ａ When forming an anhydride with the M １ａ , M ２ａ does not exist. １ａ , M ２ａ : are the same or different and represent a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 or more and 2 or less.

[0009]

[0010] [In the formula, R ４ａ , R ５ａ R: the same or different, a hydrogen atom or a methyl group ６ａ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ１ (CO) ｐ１ O (AO) ｎ１ R ７a R ７ａ : a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; AO: an alkyleneoxy group having 2 to 4 carbon atoms; n1: the average number of moles of AO added, which is a number of 100 to 150; q1: a number of 0 to 6; p1: 0 or 1; M ３ａ : hydrogen atom, alkali metal, alkaline earth metal (1 / 2 atom), ammonium group, alkylammonium group, substituted alkylammonium group, alkyl group, hydroxyalkyl group or alkenyl group; r: a number of 0 or more and 2 or less.

[0011] The present invention also relates to a clay-containing gypsum slurry containing the component (A), clay-containing gypsum, and water.

[0012] The present invention also relates to a method for producing a clay-containing gypsum slurry, which includes the following steps 1 and 2. <Step 1> A step of foaming a liquid composition containing (C) a foaming agent and water to obtain a foam. <Step 2> A step of mixing a dispersant for clay-containing gypsum slurries containing the component (A), clay-containing gypsum, water, and the foam obtained in step 1.

[0013] The present invention also relates to the use of a dispersant containing the component (A) in a clay-containing gypsum slurry.

[0014] The present invention also relates to a method for improving the water reducing ability of a clay-containing gypsum slurry, which comprises mixing a dispersant for a clay-containing gypsum slurry containing the component (A) with the clay-containing gypsum slurry.

[0015] The present invention also relates to an additive kit for clay-containing gypsum slurries, which comprises a first agent containing the component (A) and a second agent containing a foaming agent (C).

[0016] According to the present invention, a dispersant for clay-containing gypsum slurries is provided which can impart excellent water reducing properties to gypsum slurry, suppress delays in setting time, and increase the air bubble diameter in the gypsum hardened body when the gypsum slurry contains air bubbles, even when gypsum containing clay is used; and a clay-containing gypsum slurry is provided which has excellent water reducing properties, suppresses delays in setting time, and increases the air bubble diameter in the gypsum hardened body when the gypsum slurry contains air bubbles, even when gypsum containing clay is used.

[0017] Modes for Carrying Out the Invention The clay-containing gypsum slurry dispersant of the present invention can impart excellent water-reducing properties to the gypsum slurry, even when using gypsum containing clay, suppress delays in setting time, and increase the bubble diameter in the gypsum hardened body when the gypsum slurry contains bubbles. The reason why the clay-containing gypsum slurry of the present invention has excellent water-reducing properties, suppresses delays in setting time, and increases the bubble diameter in the gypsum hardened body when the gypsum slurry contains bubbles, even when using gypsum containing clay, is not necessarily clear, but is presumed to be as follows. It is presumed that when gypsum containing clay is used in the gypsum slurry, the gypsum and the clay have different charges and undergo hetero-coagulation, resulting in the retention of free water and reduced water-reducing properties. It is also presumed that when a polycarboxylic acid-based dispersant is used in the clay-containing gypsum slurry, the alkyleneoxy chains introduced as steric repulsive groups of the polymer, which is the polycarboxylic acid-based dispersant, are adsorbed to the clay, making it impossible to efficiently adsorb to the gypsum, thereby reducing the water-reducing properties. In the present invention, component (A) is a specific polycarboxylic acid dispersant containing a specific constituent monomer (A2) having an average number of added moles of alkyleneoxy groups of 100 or more and 150 or less, and in which a specific constituent monomer (A1) such as methacrylic acid accounts for less than 5 mass% of the total amount of constituent monomer (A1) and constituent monomer (A2). By using component (A), which is a specific polycarboxylic acid dispersant, the long alkyleneoxy chain contains a large amount of constituent monomer (A2) that is easily adsorbed to clay, and the proportion of constituent monomer (A1) that is easily adsorbed to gypsum is less than 5 mass%, making it easy to adsorb to clay. Component (A) is therefore efficiently adsorbed to clay. Therefore, it is presumed that the remaining portion of component (A) that is not adsorbed to clay, or an optional polycarboxylic acid dispersant (preferably component (B)) used in combination with component (A) can be efficiently acted on the gypsum, thereby imparting excellent water-reducing properties to the gypsum slurry. Furthermore, when the dispersant of the present invention, which has excellent water-reducing properties, is used, the amount of dispersant required to obtain the same fluidity can be reduced, and therefore the amount of dispersant adsorbed to the gypsum particles is reduced, and the amount of dispersant that inhibits the hydration reaction of the gypsum particles is reduced, which is thought to have suppressed delays in setting.Furthermore, when the gypsum slurry contains bubbles, the polycarboxylic acid-based dispersant has an alkyleneoxy chain as a steric repulsion unit in its structure, which has the property of stabilizing bubbles, so that the bubbles in the gypsum slurry do not break down or coalesce, resulting in a small bubble diameter after the gypsum slurry hardens. However, the dispersant of the present invention, by using component (A), has excellent water reducing properties and can reduce the amount used in the gypsum slurry. Therefore, it is presumed that this prevents the stabilization of bubbles in the gypsum slurry, promotes the coalescence of bubbles due to bubble breakage, and increases the bubble diameter in the gypsum hardened body.

[0018] [Dispersant for Clay-Containing Gypsum Slurry] <Component (A)> The dispersant for clay-containing gypsum slurry of the present invention contains, as component (A), a copolymer containing, as constituent monomers, a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2), wherein the proportion of the constituent monomer (A1) in the total amount of the constituent monomer (A1) and the constituent monomer (A2) is less than 5 mass % and the weight average molecular weight is 50,000 or more and 250,000 or less.

[0019]

[0020] [In the formula, R １ａ , R ２ａ , R ３ａ : the same or different, a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ａ and (CH ２ ) ｒ COOM ２ａ is COOM １ａ or other (CH ２ ) ｒ COOM ２ａ When forming an anhydride with the M １ａ , M ２ａ does not exist. １ａ , M ２ａ : are the same or different and represent a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 or more and 2 or less.

[0021]

[0022] [In the formula, R ４ａ , R ５ａ R: the same or different, a hydrogen atom or a methyl group ６ａ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ１ (CO) ｐ１ O (AO) ｎ１ R ７a R ７ａ : a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; AO: an alkyleneoxy group having 2 to 4 carbon atoms; n1: the average number of moles of AO added, which is a number of 100 to 150; q1: a number of 0 to 6; p1: 0 or 1; M ３ａ : hydrogen atom, alkali metal, alkaline earth metal (1 / 2 atom), ammonium group, alkylammonium group, substituted alkylammonium group, alkyl group, hydroxyalkyl group or alkenyl group; r: a number of 0 or more and 2 or less.

[0023] In general formula (A1), from the viewpoint of availability, R １ａ In the general formula (A1), from the viewpoints of availability and copolymerizability with the constituent monomer (A2), R ２ａ is preferably a hydrogen atom or a methyl group, more preferably a methyl group. ３ａ is preferably a hydrogen atom. ２ ) ｒ COOM ２ａ About COOM １ａ or other (CH ２ ) ｒ COOM ２ａ and an anhydride may be formed, in which case the M １ａ , M ２ａ does not exist. １ａ and M ２ａare the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group. １ａ and M ２ａ The alkyl group, hydroxyalkyl group, and alkenyl group preferably each have 1 to 4 carbon atoms. １ａ and M ２ａ are the same or different and are preferably a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, or an alkylammonium group, more preferably a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), or an ammonium group, still more preferably a hydrogen atom, an alkali metal, or an alkaline earth metal (1 / 2 atom), and still more preferably a hydrogen atom or an alkali metal. ２ ) ｒ COOM ２ａ r is preferably 0.

[0024] In general formula (A2), R ４ａ is preferably a hydrogen atom from the viewpoint of availability. ５ａ In view of availability and copolymerizability with the constituent monomer (A1), R is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. ６ａ is preferably a hydrogen atom from the viewpoint of availability. ７ａis preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoints of ease of production and quality stability of the product. In general formula (A2), AO is preferably a group selected from an ethyleneoxy group and a propyleneoxy group, more preferably an ethyleneoxy group, from the viewpoints of availability and cost. AO preferably contains an ethyleneoxy group. In general formula (A2), n1 is the average number of moles of AO added, and from the viewpoint of dispersibility of the clay-containing gypsum slurry, it is 100 or more, preferably 110 or more, more preferably 115 or more, and 150 or less, preferably 140 or less, more preferably 130 or less. Furthermore, when AO contains alkyleneoxy groups with different carbon numbers in an average of n1 repeating units, these alkyleneoxy groups with different carbon numbers may be randomly added or block added, or a mixture of these. Of all AO, ethyleneoxy groups are preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and it is further preferred that all AO are ethyleneoxy groups. For example, AO may contain a propyleneoxy group, a butyleneoxy group, or the like in addition to an ethyleneoxy group. In general formula (A2), from the viewpoint of availability, q1 is preferably 0, 1, or 2, more preferably 0 or 1, and even more preferably 0. ２ ) ｒ COOM ３ａ M ３ａ A preferred embodiment of is M １ａ , M ２ａ and r is preferably 0.

[0025] Of all the constituent monomers of the component (A), the proportion of constituent monomer (A1) in the total amount of constituent monomer (A1) and constituent monomer (A2) is, from the viewpoint of adsorption to clay and non-adsorption to gypsum, preferably 0.1 mass% or more, more preferably 0.5 mass% or more, even more preferably 1 mass% or more, and is less than 5 mass%, preferably 4 mass% or less, more preferably 3 mass% or less.

[0026] Of all the constituent monomers of the component (A), the proportion of constituent monomer (A1) in the total amount of constituent monomer (A1) and constituent monomer (A2) is, from the viewpoint of adsorption to clay and non-adsorption to gypsum, preferably 35 mol% or more, more preferably 45 mol% or more, even more preferably 55 mol% or more, and preferably 75 mol% or less, more preferably 70 mol% or less, even more preferably 65 mol% or less.

[0027] Of all the constituent monomers of component (A), the proportion of constituent monomer (A2) in the total amount of constituent monomer (A1) and constituent monomer (A2) is, from the viewpoint of adsorption to clay, preferably 95% by mass or more, more preferably 96% by mass or more, even more preferably 97% by mass or more, and preferably 99.9% by mass or less, preferably 99.5% by mass or less, more preferably 99.0% by mass or less.

[0028] Of all the constituent monomers of component (A), the proportion of constituent monomer (A2) in the total amount of constituent monomer (A1) and constituent monomer (A2) is, from the viewpoint of adsorption to clay, preferably 25 mol% or more, more preferably 30 mol% or more, even more preferably 35 mol% or more, and preferably 65 mol% or less, more preferably 55 mol% or less, even more preferably 45 mol% or less.

[0029] Of all the constituent monomers of component (A), the total amount of constituent monomer (A1) and constituent monomer (A2) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and preferably 100% by mass or less, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body. This total amount may be 100% by mass. Of all the constituent monomers of component (A), the total amount of constituent monomer (A1) and constituent monomer (A2) is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body. This total amount may be 100 mol%.

[0030] The copolymer of component (A) may contain a constituent monomer other than constituent monomer (A1) and constituent monomer (A2) [hereinafter also referred to as constituent monomer (A3)]. Examples of constituent monomer (A3) include hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-(methacryloyloxy)ethyl phosphate (HEMA-P), 2-hydroxyethyl acrylate (HEA), methyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate (HEMA), allylsulfonic acid, methallylsulfonic acid, and salts thereof, such as alkali metal salts, alkaline earth metal salts, ammonium salts, or amine salts. Further examples include structural units using one or more monomers selected from (meth)acrylamide, N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, 2-(meth)acrylamide-2-methasulfonic acid, 2-(meth)acrylamide-2-ethanesulfonic acid, 2-(meth)acrylamide-2-propanesulfonic acid, styrene, styrenesulfonic acid, etc. (Meth)acryl means acrylic or methacrylic.

[0031] The copolymer of component (A) may contain a constituent monomer having a phosphoric acid monoester or diester, but the amount is limited in order to prevent gelation due to molecular weight increase. Examples of constituent monomers having a phosphoric acid monoester include phosphoric acid monoesters of organic hydroxy compounds. Specific examples include polyalkylene glycol mono(meth)acrylate acid phosphoric acid esters. Further examples include compounds selected from phosphoric acid mono-[(2-hydroxyethyl)methacrylic acid] esters and phosphoric acid mono-[(2-hydroxyethyl)acrylic acid] esters. Examples of constituent monomers having a phosphoric acid diester include phosphoric acid diesters of organic hydroxy compounds. Specific examples include polyalkylene glycol di(meth)acrylate acid phosphoric acid diesters. Further examples include compounds selected from phosphoric acid di-[(2-hydroxyethyl)methacrylic acid] esters and phosphoric acid di-[(2-hydroxyethyl)acrylic acid] esters.

[0032] When all the constituent monomers of component (A) contain a constituent monomer having a phosphoric acid monoester or diester, the proportion of the constituent monomer having a phosphoric acid monoester or diester is preferably 10 mol % or less, more preferably 1 mol % or less, and even more preferably 0.1 mol % or less, from the viewpoint of suppressing gelation due to molecular weight increase. When all the constituent monomers of component (A) contain a constituent monomer having a phosphoric acid monoester or diester, the proportion of the constituent monomer having a phosphoric acid monoester or diester is preferably 10 mass % or less, more preferably 1 mass % or less, and even more preferably 0.1 mass % or less, from the viewpoint of suppressing gelation due to molecular weight increase. The copolymer of component (A) does not have to contain a constituent monomer having a phosphoric acid monoester or diester.

[0033] The weight average molecular weight (Mw) of the (A) component is 50,000 or more, preferably 80,000 or more, more preferably 100,000 or more, even more preferably 120,000 or more, and is 250,000 or less, preferably 230,000 or less, more preferably 200,000 or less, even more preferably 180,000 or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting retardation, and increasing the air bubble diameter in the gypsum hardened body.

[0034] The ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the component (A) is preferably 1.0 or more, more preferably 1.3 or more, even more preferably 1.5 or more, and preferably 3.0 or less, more preferably 2.8 or less, even more preferably 2.5 or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0035] The weight average molecular weight (Mw) and number average molecular weight (Mn) of component (A) were measured by gel permeation chromatography (GPC) under the following conditions. *GPC conditions: Apparatus: GPC (HLC-8320GPC) manufactured by Tosoh Corporation; Column: G4000PWXL + G2500PWXL (manufactured by Tosoh Corporation); Eluent: 0.2 M phosphate buffer / CH ３CN = 9 / 1 Flow rate: 1.0 mL / min Column temperature: 40°C Detection: RI Sample size: 0.2 mg / mL Standard substance: Polyethylene glycol equivalent (monodisperse polyethylene glycol with known molecular weights, molecular weights 250,000, 145,000, 87,500, 46,000, and 24,000)

[0036] From the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body, the content of the component (A) in the dispersant for a clay-containing gypsum slurry of the present invention is preferably 20% by mass or more, more preferably 25% by mass or more, even more preferably 30% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less.

[0037] <Component (B)> From the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body, the dispersant for clay-containing gypsum slurries of the present invention preferably contains, as component (B), a copolymer containing, as constituent monomers, a constituent monomer (B1) represented by the following general formula (B1) and a constituent monomer (B2) represented by the following general formula (B2), wherein the proportion of the constituent monomer (B1) in the total amount of the constituent monomer (B1) and the constituent monomer (B2) is 5% by mass or more and less than 13% by mass.

[0038]

[0039] [In the formula, R １ｂ , R ２ｂ , R ３ｂ : the same or different, a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ｂ and (CH ２ ) ｒ COOM ２ｂ is COOM １ｂ or other (CH ２ ) ｒ COOM ２ｂ When forming an anhydride with the M １ｂ , M ２ｂ does not exist. １ｂ , M ２ｂ: are the same or different and represent a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 or more and 2 or less.

[0040]

[0041] [In the formula, R ４ｂ , R ５ｂ R: the same or different, a hydrogen atom or a methyl group ６ｂ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ｂ , or (CH ２ ) ｑ２ (CO) ｐ２ O (AO) ｎ２ R ７ｂ R ７ｂ : a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; AO: an alkyleneoxy group having 2 to 4 carbon atoms; n2: the average number of moles of AO added, which is a number of 5 to 300; q2: a number of 0 to 6; p2: 0 or 1; M ３ｂ : hydrogen atom, alkali metal, alkaline earth metal (1 / 2 atom), ammonium group, alkylammonium group, substituted alkylammonium group, alkyl group, hydroxyalkyl group or alkenyl group; r: a number of 0 or more and 2 or less.

[0042] In general formula (B1), from the viewpoint of availability, R １ｂ In the general formula (B1), from the viewpoints of availability and copolymerizability with the constituent monomer (B2), R ２ｂ is preferably a hydrogen atom or a methyl group, more preferably a methyl group. ３b is preferably a hydrogen atom. ２ ) ｒ COOM ２ｂ About COOM １ｂ or other (CH ２ ) ｒ COOM ２ｂ and an anhydride may be formed, in which case the M １ｂ , M２ｂ does not exist. １ｂ and M ２ｂ are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group. １ｂ and M ２ｂ The alkyl group, hydroxyalkyl group, and alkenyl group preferably each have 1 to 4 carbon atoms. １ｂ and M ２ｂ are the same or different and are preferably a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, or an alkylammonium group, more preferably a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), or an ammonium group, still more preferably a hydrogen atom, an alkali metal, or an alkaline earth metal (1 / 2 atom), and still more preferably a hydrogen atom or an alkali metal. ２ ) ｒ COOM ２ｂ r is preferably 0.

[0043] In general formula (B2), R ４ｂ is preferably a hydrogen atom from the viewpoint of availability. ５ｂ In view of availability and copolymerizability with the constituent monomer (B1), R is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. ６ｂ is preferably a hydrogen atom from the viewpoint of availability. ７ｂis preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoints of ease of production and quality stability of the product. In general formula (B2), AO is preferably a group selected from an ethyleneoxy group and a propyleneoxy group, more preferably an ethyleneoxy group, from the viewpoints of availability and price. AO preferably contains an ethyleneoxy group. In general formula (B2), n2 is the average number of moles of AO added, and from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the bubble diameter in the gypsum hardened body, it is 5 or more, preferably 50 or more, more preferably 90 or more, even more preferably 100 or more, still more preferably 110 or more, and 300 or less, preferably 150 or less, more preferably 130 or less. Furthermore, when AO contains alkyleneoxy groups with different carbon numbers in an average of n2 repeating units, these alkyleneoxy groups with different carbon numbers may be randomly added, block added, or a mixture thereof. In all AOs, ethyleneoxy groups are preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, and it is further preferred that all AOs are ethyleneoxy groups. For example, AOs may contain propyleneoxy groups, butyleneoxy groups, etc. in addition to ethyleneoxy groups. In general formula (B2), from the viewpoint of availability, q2 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. In general formula (B2), (CH ２ ) ｒ COOM ３ｂ M ３ｂ A preferred embodiment of is M １ｂ , M ２ｂ and r is preferably 0.

[0044] Of all the constituent monomers of the component (B), the proportion of the constituent monomer (B1) in the total amount of the constituent monomer (B1) and the constituent monomer (B2) is 5% by mass or more, preferably 6% by mass or more, and less than 13% by mass, preferably 12.5% ​​by mass or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0045] Of all the constituent monomers of the component (B), the proportion of the constituent monomer (B1) in the total amount of the constituent monomer (B1) and the constituent monomer (B2) is preferably 70 mol % or more, more preferably 75 mol % or more, even more preferably 80 mol % or more, and preferably 95 mol % or less, more preferably 92 mol % or less, and even more preferably 90 mol % or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0046] Of all the constituent monomers of the component (B), the proportion of the constituent monomer (B2) in the total amount of the constituent monomer (B1) and the constituent monomer (B2) is preferably 87% by mass or more, more preferably 87.5% by mass or more, and preferably 95% by mass or less, and preferably 94% by mass or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0047] Of all the constituent monomers of the component (B), the proportion of the constituent monomer (B2) in the total amount of the constituent monomer (B1) and the constituent monomer (B2) is preferably 5 mol % or more, more preferably 8 mol % or more, even more preferably 10 mol % or more, and preferably 30 mol % or less, more preferably 25 mol % or less, and even more preferably 20 mol % or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0048] Of all the constituent monomers of component (B), the total amount of constituent monomer (B1) and constituent monomer (B2) is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and preferably 100% by mass or less, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body. This total amount may be 100% by mass. Of all the constituent monomers of component (B), the total amount of constituent monomer (B1) and constituent monomer (B2) is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body. This total amount may be 100 mol%.

[0049] The copolymer of component (B) may contain a constituent monomer other than constituent monomer (B1) and constituent monomer (B2) [hereinafter also referred to as constituent monomer (B3)]. Examples of constituent monomer (B3) include hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-(methacryloyloxy)ethyl phosphate (HEMA-P), 2-hydroxyethyl acrylate (HEA), methyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate (HEMA), allylsulfonic acid, methallylsulfonic acid, and salts thereof, such as alkali metal salts, alkaline earth metal salts, ammonium salts, or amine salts. Further examples include structural units using one or more monomers selected from (meth)acrylamide, N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, 2-(meth)acrylamide-2-methasulfonic acid, 2-(meth)acrylamide-2-ethanesulfonic acid, 2-(meth)acrylamide-2-propanesulfonic acid, styrene, styrenesulfonic acid, etc. (Meth)acryl means acrylic or methacrylic.

[0050] The weight average molecular weight (Mw) of the (B) component is preferably 45,000 or more, more preferably 50,000 or more, even more preferably 55,000 or more, and preferably 80,000 or less, more preferably 75,000 or less, and even more preferably 70,000 or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body. The ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the (B) component is preferably 1.45 or more, more preferably 1.50 or more, even more preferably 1.52 or more, and preferably 1.66 or less, more preferably 1.64 or less, and even more preferably 1.62 or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body. The weight average molecular weight (Mw) and number average molecular weight (Mn) of component (B) were measured by gel permeation chromatography (GPC) under the same conditions as those described for component (A).

[0051] When the dispersant for a clay-containing gypsum slurry of the present invention contains the component (B), the content of the component (B) is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 60% by mass or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0052] When the dispersant for a clay-containing gypsum slurry of the present invention contains the component (B), the mass ratio (A) / ((A)+(B)) of the content of the component (A) to the total content of the components (A) and (B) is preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.6 or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0053] The clay-containing gypsum slurry dispersant of the present invention may contain water. When the clay-containing gypsum slurry dispersant of the present invention contains water, the water content is preferably 40% by mass or more, preferably 45% by mass or more, more preferably 50% by mass or more, and preferably 75% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less.

[0054] The clay-containing gypsum slurry dispersant of the present invention may contain a nitrogen-containing compound, but the content is limited from the viewpoint of improving dispersibility. The nitrogen-containing compound may be one or more selected from ammonia, alkylamines, alkanolamines, alkylalkanolamines, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and polyethyleneimine (those having an average condensation number of ethyleneimino groups of 4 or more, more preferably 5 or more).

[0055] When the dispersant for a clay-containing gypsum slurry of the present invention contains a nitrogen-containing compound, the content of the nitrogen-containing compound is preferably 1 mass % or less, more preferably 0.1 mass % or less, and even more preferably 0.01 mass % or less, from the viewpoint of improving dispersibility. The dispersant for a clay-containing gypsum slurry of the present invention does not necessarily contain a nitrogen-containing compound.

[0056] The clay-containing gypsum slurry dispersant of the present invention can optionally contain a thickener, a chelating agent, a heavy metal scavenger, a rust inhibitor, a preservative, a colorant, a fragrance, an antifoaming agent, a solvent, a flocculant, a water-soluble polymer, etc. However, these do not fall under the category of component (A) and component (B).

[0057] The dispersant for clay-containing gypsum slurries of the present invention can be suitably used as a dispersant for gypsum slurries containing gypsum that contains clay. In particular, the dispersant for clay-containing gypsum slurries of the present invention can be suitably used as a dispersant for gypsum slurries containing gypsum whose clay content, as determined by the methylene blue adsorption test for clay-containing gypsum (JCAS I-61-2008), is 0.5 mass% or more and 6.0 mass% or less. As the clay-containing gypsum, the one described below in connection with the clay-containing gypsum slurry of the present invention can be appropriately applied.

[0058] [Method for producing a clay-containing gypsum slurry dispersant] The present invention relates to a method for producing a clay-containing gypsum slurry dispersant, which involves mixing the component (A). The method for producing a clay-containing gypsum slurry dispersant of the present invention can further include mixing the component (B). The method for producing a clay-containing gypsum slurry dispersant of the present invention can further include mixing water. The components (A) and (B) are the same as those described for the clay-containing gypsum slurry dispersant of the present invention. The method for producing a clay-containing gypsum slurry dispersant of the present invention can appropriately apply the aspects described for the clay-containing gypsum slurry dispersant of the present invention. In the method for producing a clay-containing gypsum slurry dispersant of the present invention, the mixed amount of the component (A), the mixed amount of the component (B), the mixed amount of water, and the mass ratio (A) / ((A)+(B)) of the mixed amount of the component (A) to the total mixed amount of the component (A) and the component (B) can be appropriately applied by replacing the content of each component and the mass ratio of each component described for the clay-containing gypsum slurry dispersant of the present invention with the mixed amount.

[0059] [Use of Dispersant in Clay-Containing Gypsum Slurry] The dispersant for clay-containing gypsum slurries of the present invention can be suitably used as a dispersant for gypsum slurries containing clay-containing gypsum. That is, the present invention relates to the use of a dispersant containing the component (A) in a clay-containing gypsum slurry. The dispersant can further contain the component (B). The dispersant can further contain water. The components (A) and (B) are the same as those described for the dispersant for clay-containing gypsum slurries of the present invention. The dispersant is the same as the dispersant for clay-containing gypsum slurries of the present invention, and the aspects described for the dispersant for clay-containing gypsum slurries and its manufacturing method of the present invention can be applied as appropriate. The dispersant is suitable for use in gypsum slurries containing gypsum having a clay content of 0.5% by mass or more and 6.0% by mass or less as determined by the methylene blue adsorption test for clay-containing gypsum (JCAS I-61-2008). The clay-containing gypsum described for the clay-containing gypsum slurry of the present invention described below can be applied as appropriate.

[0060] [Clay-Containing Gypsum Slurry] The present invention provides a clay-containing gypsum slurry containing the component (A), clay-containing gypsum, and water. The clay-containing gypsum slurry of the present invention preferably further contains component (B) from the viewpoints of improving water reducing ability, suppressing setting delay, and increasing the bubble diameter in the gypsum hardened body. The clay-containing gypsum slurry of the present invention can be appropriately applied with the aspects described in the dispersant for clay-containing gypsum slurries and the method for producing the same of the present invention. The components (A) and (B) are the same as those described in the dispersant for clay-containing gypsum slurries of the present invention. The clay-containing gypsum slurry of the present invention is suitable for use in gypsum boards.

[0061] Examples of gypsum include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. Any type of gypsum can be used, including high-quality neutralized gypsum, phosphogypsum, a by-product of phosphoric acid, flue gas desulfurization gypsum generated in thermal power generation, natural gypsum containing various impurities and clay, and mixtures thereof. The clay-containing gypsum slurry of the present invention can be made with natural gypsum because it has excellent water-reducing properties even when using gypsum containing clay. The clay contained in gypsum is primarily composed of hydrous silicate minerals (hereinafter referred to as clay minerals) with a layered structure. Examples of clay minerals contained as fine particles in this clay include kaolin minerals (kaolinite, dickite, and nacrite), serpentine (lizardite, antigorite, and chrysotile), mica clay minerals (illite, sericite, glauconite, and celadonite), chlorite, vermiculite, and smectite (montmorillonite, beidellite, nontronite, saponite, and hectorite).

[0062] The clay content of clay-containing gypsum measured by the methylene blue adsorption test (Cement Association Standard Test Method JCAS I-61-2008) is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, even 2.0% by mass or more, even 3.0% by mass or more, even 4.0% by mass or more, and preferably 6.0% by mass or less, more preferably 5.0% by mass or less, from the viewpoint of the range in which component (A) efficiently acts on the clay. The methylene blue adsorption test is commonly known as a method for measuring the active clay content in sand. The measurement principle involves titrating the amount of methylene blue adsorbed to the sand, and the degree of bleeding (halo) of the spot on the filter paper is used to determine the result.

[0063] The clay-containing gypsum slurry of the present invention has a water / gypsum ratio of preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more from the viewpoint of workability, and preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less from the viewpoint of reducing fuel costs. Here, the water / gypsum ratio is the mass percentage (mass%) of the water content and the gypsum content in the clay-containing gypsum slurry, and is calculated by multiplying water / gypsum by 100. In the present invention, the amount of clay contained in the gypsum is also included in the amount of gypsum. The same applies to other quantitative relationships of the clay-containing gypsum slurry regarding gypsum.

[0064] In the clay-containing gypsum slurry of the present invention, the content of the component (A) relative to 100 parts by mass of gypsum is, from the viewpoints of improving water reducing ability, suppressing setting retardation, and increasing the diameter of bubbles in the gypsum hardened body, preferably 0.01 parts by mass or more, more preferably 0.04 parts by mass or more, even more preferably 0.06 parts by mass or more, still more preferably 0.08 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, and even more preferably 0.3 parts by mass or less.

[0065] When the clay-containing gypsum slurry of the present invention contains the component (B), the content of the component (B) relative to 100 parts by mass of gypsum is, from the viewpoints of improving water reducing ability, suppressing setting retardation, and increasing the diameter of air bubbles in the gypsum hardened body, preferably 0.01 parts by mass or more, more preferably 0.04 parts by mass or more, even more preferably 0.06 parts by mass or more, still more preferably 0.08 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, and even more preferably 0.3 parts by mass or less.

[0066] When the clay-containing gypsum slurry of the present invention contains the component (B), the mass ratio (A) / ((A)+(B)) of the content of the component (A) to the total content of the component (A) and the component (B) is preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.6 or less, from the viewpoints of improving water reducing ability, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0067] The clay-containing gypsum slurry of the present invention preferably contains a foaming agent as component (C) from the viewpoint of reducing the specific gravity of the clay-containing gypsum hardened body.

[0068] Examples of foaming agents for component (C) include sulfonic acid compounds, ether sulfate ester compounds, carboxylic acid compounds, phosphonic acid compounds, and phosphoric acid compounds having a hydrocarbon group containing 8 to 18 carbon atoms. Examples include alkyl or alkenyl sulfate esters having alkyl or alkenyl groups, alkyl or alkenyl sulfonic acids having alkyl or alkenyl groups, polyoxyalkylene alkyl or alkenyl ether sulfate esters having alkyl or alkenyl groups, polyoxyalkylene alkyl or alkenyl ether carboxylic acids having alkyl or alkenyl groups, and salts thereof. Examples of salts of these compounds include alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0069] From the viewpoint of foaming ability, particularly foaming performance, in aqueous systems, component (C) is preferably one or more selected from alkyl or alkenyl sulfate esters having an alkyl or alkenyl group containing from 8 to 18 carbon atoms, alkyl or alkenyl sulfonic acids having an alkyl or alkenyl group containing from 8 to 18 carbon atoms, polyoxyalkylene alkyl or alkenyl ether sulfate esters having an alkyl or alkenyl group containing from 8 to 18 carbon atoms, and salts thereof. Examples of salts of these compounds include one or more selected from alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0070] From the viewpoint of foaming ability, particularly among foam performance in aqueous systems, the component (C) is preferably at least one selected from (C1) an alkyl or alkenyl sulfate ester or a salt thereof having an alkyl or alkenyl group having from 8 to 18 carbon atoms (hereinafter referred to as component (C1)), and (C2) a polyoxyalkylene alkyl or alkenyl ether sulfate ester or a salt thereof having an alkyl or alkenyl group having from 8 to 18 carbon atoms (hereinafter referred to as component (C2)).

[0071] From the viewpoint of increasing the diameter of bubbles in the gypsum hardened body, the component (C1) preferably has an alkyl or alkenyl group, preferably an alkyl group, having a carbon number of 8 or more, more preferably 10 or more, and preferably 18 or less, more preferably 16 or less, even more preferably 14 or less, and still more preferably 12 or less. Examples of the salt of the component (C1) include one or more selected from alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0072] Specific examples of the component (C1) include one or more compounds selected from octyl sulfate, decyl sulfate, dodecyl sulfate, tetradecyl sulfate, hexadecyl sulfate, octadecyl sulfate, 2-ethylhexyl sulfate, 2-propylheptyl sulfate, and salts thereof. From the viewpoint of increasing the diameter of air bubbles in the gypsum hardened body, the component (C1) preferably contains one or more compounds selected from decyl sulfate, dodecyl sulfate, tetradecyl sulfate, and salts thereof, and more preferably contains one or more compounds selected from decyl sulfate, dodecyl sulfate, and salts thereof.

[0073] From the viewpoint of foaming performance, particularly foaming ability, in aqueous systems, component (C) may contain, as component (C1), two types of alkyl or alkenyl sulfate esters or salts thereof, each having a different number of carbon atoms in the alkyl or alkenyl group.

[0074] From the viewpoint of increasing the diameter of bubbles in the gypsum hardened body, component (C2) preferably has an alkyl or alkenyl group, preferably an alkyl group, having 8 or more carbon atoms, more preferably 10 or more, and preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less. The oxyalkylene group of component (C2) is an oxyethylene group or an oxypropylene group, preferably an oxyethylene group. From the viewpoint of foaming performance, particularly foamability, in aqueous systems, the average number of moles of oxyalkylene groups added is preferably 1 or more, more preferably 2 or more, and from the viewpoint of foaming performance, particularly foamability, in aqueous systems, it is preferably 10 or less, more preferably 6 or less, and even more preferably 4 or less. Examples of salts of component (C2) include one or more selected from alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0075] Specific examples of the component (C2) include polyoxyethylene octyl ether sulfate, polyoxyethylene decyl ether sulfate, polyoxyethylene lauryl ether sulfate, polyoxyethylene tridecyl ether sulfate, polyoxyethylene myristyl ether sulfate, polyoxyethylene cetyl ether sulfate, polyoxyethylene stearyl ether sulfate, polyoxypropylene octyl ether sulfate, polyoxypropylene decyl ether sulfate, polyoxypropylene lauryl ether sulfate, polyoxypropylene tridecyl ether sulfate, polyoxypropylene myristyl ether sulfate, polyoxypropylene cetyl ether sulfate, polyoxypropylene stearyl ether sulfate, polyoxyethylene polyoxypropylene octyl ether sulfate, polyoxyethylene polyoxypropylene decyl ether sulfate, and polyoxyethylene polyoxypropylene lauryl ether sulfate. Examples of the gypsum slurries include one or more selected from polyoxyethylene polyoxypropylene tridecyl ether sulfate, polyoxyethylene polyoxypropylene myristyl ether sulfate, polyoxyethylene polyoxypropylene cetyl ether sulfate, polyoxyethylene polyoxypropylene stearyl ether sulfate, and salts thereof. From the viewpoint of increasing the diameter of bubbles in the gypsum slurry, preferred are one or more selected from polyoxyethylene decyl ether sulfate, polyoxyethylene lauryl ether sulfate, polyoxyethylene myristyl ether sulfate, polyoxypropylene decyl ether sulfate, polyoxypropylene lauryl ether sulfate, polyoxypropylene myristyl ether sulfate, polyoxyethylene polyoxypropylene decyl ether sulfate, polyoxyethylene polyoxypropylene lauryl ether sulfate, polyoxypropylene myristyl ether sulfate, polyoxyethylene polyoxypropylene decyl ether sulfate, polyoxyethylene polyoxypropylene lauryl ether sulfate, polyoxyethylene polyoxypropylene myristyl ether sulfate, and salts thereof.

[0076] When the clay-containing gypsum slurry of the present invention contains the component (C), the content of the component (C) relative to 100 parts by mass of water is preferably 0.1 part by mass or more, more preferably 0.2 part by mass or more, even more preferably 0.3 part by mass or more, and preferably 1.0 part by mass or less, more preferably 0.9 part by mass or less, and even more preferably 0.8 part by mass or less, from the viewpoint of reducing the specific gravity of the clay-containing gypsum hardened body.

[0077] The clay-containing gypsum slurry of the present invention may contain the above-mentioned nitrogen-containing compound, but the content thereof is limited from the viewpoint of improving dispersibility. When the clay-containing gypsum slurry of the present invention contains a nitrogen-containing compound, the content of the nitrogen-containing compound is preferably 0.1 parts by mass or less, more preferably 0.01 parts by mass or less, and even more preferably 0.001 parts by mass or less, relative to 100 parts by mass of gypsum, from the viewpoint of improving dispersibility. The clay-containing gypsum slurry of the present invention does not need to contain a nitrogen-containing compound.

[0078] The clay-containing gypsum slurry of the present invention can contain additives used for gypsum boards, etc. Such additives include antifoaming agents, foam stabilizers, set regulators, water repellents, adhesives, retarders, etc. (excluding those corresponding to components (A), (B), and (C)). Gypsum boards can also be produced by adding reinforcing fibers such as glass fiber, carbon fiber, waste paper, virgin pulp, etc., or by adding lightweight aggregates such as perlite or foamed steel.

[0079] The clay-containing gypsum slurry of the present invention is dried and cured to obtain a gypsum hardened body. The specific gravity of the hardened body of the clay-containing gypsum slurry of the present invention is preferably 0.3 or more, more preferably 0.4 or more, and even more preferably 0.5 or more from the viewpoint of strength, and is preferably 0.9 or less, more preferably 0.8 or less, and even more preferably 0.7 or less from the viewpoint of handleability.

[0080] The clay-containing gypsum slurry of the present invention preferably contains bubbles. When bubbles are contained, the average bubble diameter of the hardened body of the clay-containing gypsum slurry of the present invention is preferably 230 μm or more, more preferably 250 μm or more, even more preferably 300 μm or more, from the viewpoint of improving the strength of the hardened body, and from the viewpoint of cross-sectional appearance, it is preferably 800 μm or less, more preferably 700 μm or less, even more preferably 600 μm or less, even more preferably 500 μm or less, and even more preferably 400 μm or less. The average bubble diameter is calculated by preparing a hardened body of the clay-containing gypsum slurry, arbitrarily cutting the hardened body to create a cross section, observing the cross section with a digital microscope, measuring the diameter of 200 to 400 bubble cross sections, and averaging these values ​​(arithmetic mean). Note that the measurement of the diameter of the bubble cross section is the diameter when the bubble cross section is circular, the major axis when the bubble cross section is elliptical, and the longest part when the bubble cross section is irregular.

[0081] By containing air bubbles, the clay-containing gypsum slurry can reduce the specific gravity of the hardened body of the clay-containing gypsum slurry and make it lighter. However, if the volume (proportion) of air bubbles is increased to further reduce the weight of the hardened body of the clay-containing gypsum slurry, the proportion of the clay-containing gypsum slurry decreases, and the strength of the hardened body tends to decrease. On the other hand, as described in paragraph 0004 of JP-A-10-330174, in a clay-containing gypsum slurry containing air bubbles of the same specific gravity, by increasing the air bubble diameter in the gypsum slurry, the strength of the hardened body of the clay-containing gypsum slurry can be increased. Furthermore, when the air bubble diameter in the clay-containing gypsum slurry containing air bubbles is increased, drying when obtaining a hardened body of the gypsum slurry is accelerated, reducing fuel costs for drying and CO ２ Increasing the bubble diameter in the clay-containing gypsum slurry increases the distance between the bubbles, making it harder for the bubbles to communicate with each other, improving thermal insulation and sound insulation.

[0082] [Method for producing clay-containing gypsum slurry] The present invention relates to a method for producing a clay-containing gypsum slurry, which comprises mixing the component (A), clay-containing gypsum, and water. The method for producing a clay-containing gypsum slurry of the present invention can further include mixing the component (B). The method for producing a clay-containing gypsum slurry of the present invention can further include mixing the component (C). The components (A) and (B) are the same as those described for the dispersant for clay-containing gypsum slurries of the present invention. The clay-containing gypsum and the component (C) are the same as those described for the clay-containing gypsum slurry of the present invention. In the method for producing a clay-containing gypsum slurry of the present invention, the mixing amounts of each component and their mass ratios can be appropriately applied by replacing the contents of each component and the mass ratios thereof described for the clay-containing gypsum slurry of the present invention with the mixing amounts.

[0083] The clay-containing gypsum slurry of the present invention can be produced using the clay-containing gypsum slurry dispersant of the present invention. That is, the present invention provides a method for producing a clay-containing gypsum slurry, which includes the following steps 1 and 2. <Step 1> A step of foaming a liquid composition containing a foaming agent (C) (hereinafter referred to as component (C)) and water to obtain a foam. <Step 2> A step of mixing the clay-containing gypsum slurry dispersant of the present invention containing component (A), clay-containing gypsum, water, and the foam obtained in step 1. Note that in step 2, a clay-containing gypsum slurry containing the clay-containing gypsum slurry dispersant of the present invention, clay-containing gypsum, and water may be prepared, and the clay-containing gypsum slurry may be mixed with the foam obtained in step 1.

[0084] This manufacturing method allows the preparation of a clay-containing gypsum slurry of the present invention containing bubbles. The manufacturing method of the clay-containing gypsum slurry of the present invention can be appropriately applied to the embodiments described for the clay-containing gypsum slurry dispersant and manufacturing method thereof of the present invention, and the clay-containing gypsum slurry of the present invention. The (C) component is the same as the embodiment described for the clay-containing gypsum slurry of the present invention. The content of the (C) component in the liquid composition in step 1 is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, and preferably 1.0 mass% or less, more preferably 0.9 mass% or less, with the remainder being water. In the manufacturing method of the clay-containing gypsum slurry of the present invention, the mixing amounts and mass ratios of each component can be appropriately applied by replacing the contents of each component with the mixing amounts for the contents and mass ratios of each component described for the clay-containing gypsum slurry of the present invention. The temperatures of the foam and the clay-containing gypsum slurry used for mixing are preferably 15°C or more and 40°C or less.

[0085] In Step 1, the liquid composition is foamed to obtain a foam at an expansion ratio that varies depending on the application of the gypsum slurry, etc., but is preferably 5 times or more, more preferably 7 times or more, and even more preferably 10 times or more from the viewpoint of economic efficiency, and is preferably 30 times or less, more preferably 25 times or less, and even more preferably 20 times or less from the viewpoint of kneadability.

[0086] In step 2, although it depends on the use of the gypsum slurry, the foam is mixed with the clay-containing gypsum slurry in an amount of preferably 50% by volume or more, more preferably 100% by volume or more, and even more preferably 150% by volume or more from the viewpoint of reducing the specific gravity of the hardened body, and in an amount of preferably 400% by volume or less, more preferably 300% by volume or less, and even more preferably 200% by volume or less from the viewpoint of the strength of the hardened body. In this production method, admixtures and additives known in the art can be mixed in step 1 and / or step 2.

[0087] After step 2, the following step 3 is further carried out to produce a hardened body of the clay-containing gypsum slurry, i.e., a gypsum board. Step 3: A step of molding and hardening the clay-containing gypsum slurry obtained in step 2. The molding and hardening can be carried out by known methods. For example, a gypsum board can be prepared by referring to "Gypsum Board Production" described on pages 322 to 324 of "Gypsum Lime Handbook" (edited by the Gypsum Lime Society).

[0088] [Method for Improving Water Reducibility of Clay-Containing Gypsum Slurry] The dispersant for clay-containing gypsum slurry of the present invention can improve the water reducibility of a clay-containing gypsum slurry by mixing it with the clay-containing gypsum slurry. That is, the method for improving water reducibility of a clay-containing gypsum slurry comprises mixing the dispersant for clay-containing gypsum slurry of the present invention, which contains component (A), with the clay-containing gypsum slurry. The clay-containing gypsum slurry mixed with the dispersant for clay-containing gypsum slurry of the present invention is the clay-containing gypsum slurry of the present invention. In the method for improving water reducibility of a clay-containing gypsum slurry of the present invention, it is preferable to produce the clay-containing gypsum slurry using the method described in the method for producing a clay-containing gypsum slurry of the present invention. That is, the method for improving water reducibility of a clay-containing gypsum slurry of the present invention preferably includes the following steps 1 and 2. <Step 1> A step of foaming a liquid composition containing component (C) and water to obtain a foam. <Step 2> A step of mixing the dispersant for clay-containing gypsum slurry of the present invention, which contains component (A), clay-containing gypsum, water, and the foam obtained in step 1. In the method for improving water reducibility of a clay-containing gypsum slurry of the present invention, the mixing amounts of each component and their mass ratios can be appropriately applied by replacing the contents of each component and the mass ratios thereof described in the clay-containing gypsum slurry of the present invention with the mixing amounts. The method for improving water reducibility of a clay-containing gypsum slurry of the present invention can be appropriately applied to the dispersant for a clay-containing gypsum slurry and the method for producing the same of the present invention, and the aspects described in the clay-containing gypsum slurry and the method for producing the same of the present invention.

[0089] [Additive Kit for Clay-Containing Gypsum Slurry] The present invention relates to an additive kit for clay-containing gypsum slurry comprising a first agent containing the component (A) and a second agent containing the component (C). The first agent containing the component (A) is a dispersant for clay-containing gypsum slurry of the present invention, and the aspects described in the dispersant for clay-containing gypsum slurry and the method for producing the same of the present invention can be applied as appropriate. The second agent containing the component (C) is an agent used in step 1 of the method for producing a clay-containing gypsum slurry of the present invention. By using the additive kit for clay-containing gypsum slurry of the present invention, the method for producing a clay-containing gypsum slurry of the present invention and the method for improving water reducibility of a clay-containing gypsum slurry of the present invention can be easily performed. The additive kit for clay-containing gypsum slurry of the present invention can be applied as appropriate to the aspects described in the dispersant for clay-containing gypsum slurry and the method for producing the same of the present invention, the clay-containing gypsum slurry and the method for producing the same of the present invention, and the method for improving water reducibility of a clay-containing gypsum slurry of the present invention.

[0090] The content of component (C) in the second agent is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, from the viewpoints of foam stabilization during foaming, enlarging the bubbles in the hydraulic composition, and reducing the weight of the hydraulic composition. From the viewpoints of enlarging the bubbles in the hydraulic composition and uniformly distributing the bubbles in the hydraulic composition, the content is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. The second agent may further contain water. When water is contained in the second agent, the content of water is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0091] In addition to the above-described embodiments, the present invention discloses the following preferred aspects. In one embodiment, the clay-containing gypsum slurry of the present invention has an (A) component content of preferably 0.01 parts by mass or more, more preferably 0.04 parts by mass or more, even more preferably 0.06 parts by mass or more, still more preferably 0.08 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, and even more preferably 0.3 parts by mass or less, relative to 100 parts by mass of gypsum, from the viewpoints of improving water reducing ability, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body, and contains a (B) component, and the mass ratio (A) / ((A)+(B)) of the content of the (A) component to the total content of the (A) component and the (B) component may be preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.6 or less, from the viewpoints of improving water reducing ability, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0092] In one embodiment of the clay-containing gypsum slurry of the present invention, the weight average molecular weight (Mw) of the component (A) is 50,000 or more, preferably 80,000 or more, more preferably 100,000 or more, and even more preferably 120,000 or more, and 250,000 or less, preferably 230,000 or less, more preferably 200,000 or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting retardation, and increasing the air bubble diameter in the gypsum hardened body. The gypsum composition preferably has a molecular weight of 180,000 or less, contains a (B) component, and has a mass ratio (A) / ((A)+(B)) of the content of the (A) component to the total content of the (A) component and the (B) component, which may be, from the viewpoints of improving water reducing ability, suppressing setting retardation, and increasing the air bubble diameter in the gypsum hardened body, preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.6 or less.

[0093] In one embodiment of the method for producing a clay-containing gypsum slurry of the present invention, the mixed amount of the (A) component, relative to 100 parts by mass of gypsum, is preferably 0.01 parts by mass or more, more preferably 0.04 parts by mass or more, even more preferably 0.06 parts by mass or more, still more preferably 0.08 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.4 parts by mass or less, and even more preferably 0.3 parts by mass or less, from the viewpoints of improving water reduction, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body. The (B) component is mixed, and the mass ratio (A) / ((A)+(B)) of the mixed amount of the (A) component to the total mixed amount of the (A) component and the (B) component may be preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.6 or less, from the viewpoints of improving water reduction, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0094] In one embodiment of the method for producing a clay-containing gypsum slurry of the present invention, the weight average molecular weight (Mw) of the component (A) is 50,000 or more, preferably 80,000 or more, more preferably 100,000 or more, and even more preferably 120,000 or more, and is 250,000 or less, preferably 230,000 or less, and more preferably 200,000 or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting retardation, and increasing the air bubble diameter in the gypsum hardened body. The mass ratio (A) / ((A)+(B)) of the mixed amount of the (A) component to the total mixed amount of the (A) component and the (B) component when the (B) component is mixed may be preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.6 or less, from the viewpoints of improving water reducing ability, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0095] In one embodiment of the use of the dispersant of the present invention in a clay-containing gypsum slurry, the dispersant contains the component (B), and the weight average molecular weight (Mw) of the component (A) is 50,000 or more, preferably 80,000 or more, more preferably 100,000 or more, and even more preferably 120,000 or more, and 250,000 or less, preferably 230,000 or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body. The molecular weight is preferably 200,000 or less, and more preferably 180,000 or less. From the viewpoints of improving water reducing ability, suppressing setting retardation, and increasing the air bubble diameter in the gypsum hardened body, the mass ratio (A) / ((A)+(B)) of the content of the component (A) to the total content of the component (A) and the component (B) may be preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.6 or less.

[0096] In one embodiment of the method for improving water reducibility of a clay-containing gypsum slurry of the present invention, the dispersant for a clay-containing gypsum slurry contains the component (B), and the mixing amount of the component (A) relative to 100 parts by mass of gypsum is, from the viewpoints of improving water reducibility, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body, preferably 0.01 parts by mass or more, more preferably 0.04 parts by mass or more, even more preferably 0.06 parts by mass or more, still more preferably 0.08 parts by mass or more, and preferably 0.5 parts by mass or less. The amount is more preferably 0.4 parts by mass or less, and even more preferably 0.3 parts by mass or less. The mass ratio (A) / ((A)+(B)) of the mixed amount of the (A) component to the total mixed amount of the (A) component and the (B) component may be preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.6 or less, from the viewpoints of improving water reducing ability, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0097] In one embodiment of the method for improving the water reducibility of a clay-containing gypsum slurry of the present invention, a dispersant for a clay-containing gypsum slurry contains component (B), and the weight average molecular weight (Mw) of component (A) is 50,000 or more, preferably 80,000 or more, more preferably 100,000 or more, even more preferably 120,000 or more, and 250,000 or less, preferably 230,000 or less, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry, suppressing setting retardation, and increasing the air bubble diameter in the gypsum hardened body. The mass ratio (A) / ((A)+(B)) of the mixed amount of the (A) component to the total mixed amount of the (A) component and the (B) component may be preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.6 or less, from the viewpoints of improving water reducing ability, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0098] In one embodiment of the additive kit for a clay-containing gypsum slurry of the present invention, the first agent contains the component (B), and the weight average molecular weight (Mw) of the component (A) is 50,000 or more, preferably 80,000 or more, more preferably 100,000 or more, even more preferably 120,000 or more, and 250,000 or less, preferably 230,000 or less, and more preferably 300,000 or less, from the viewpoints of improving the water reducing ability of the clay-containing gypsum slurry, suppressing setting retardation, and increasing the air bubble diameter in the gypsum hardened body. is 200,000 or less, and more preferably 180,000 or less, and the mass ratio (A) / ((A)+(B)) of the content of the (A) component to the total content of the (A) component and the (B) component in the first agent may be preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.6 or less, from the viewpoints of improving water reducing ability, suppressing setting delay, and increasing the air bubble diameter in the gypsum hardened body.

[0099] Examples The components (A) and (B) used in the examples and comparative examples are shown in Table 1.

[0100]

[0101] The constituent monomers used in Table 1 were as follows: MEPEG (120): methoxypolyethylene glycol (120) monomethacrylate (the number in parentheses is the average number of moles of ethylene oxide added). TPEG 2700: isoprenyl ether ethylene oxide adduct (average number of moles of ethylene oxide added: 60) Weight average molecular weight (Mw): 2700. EPEG 3000: vinyl ether ethylene oxide adduct (average number of moles of ethylene oxide added: 65) Weight average molecular weight (Mw): 3000.

[0102] <Production of Copolymer A-6> 303.64 g of water was charged into a glass reaction vessel equipped with a stirrer, and the mixture was replaced with nitrogen while stirring. The temperature was raised to 80°C in a nitrogen atmosphere. (i) A solution obtained by mixing and dissolving 653.2 g of an aqueous solution of MEPEG (120) (active content 89.117% by mass, water 40.65% by mass, containing 2.255% methacrylic acid as an impurity) and 1.28 g of mercaptoethanol, and (ii) a solution obtained by dissolving 2.50 g of ammonium persulfate in 14.15 g of water, were each added dropwise into the vessel over 1.5 hours. Next, a solution obtained by dissolving 1.25 g of ammonium persulfate in 7.07 g of water was added dropwise over 30 minutes, and the mixture was then aged at the same temperature (80°C) for 1 hour. After aging, the mixture was neutralized with 11.36 g of a 48% aqueous sodium hydroxide solution to obtain a reaction product containing copolymer A-6 and water and having a weight-average molecular weight of 54,882. The other copolymers in Table 1 were also produced in the same manner as above, but by changing the types and amounts of the constituent monomers used. Furthermore, A-1 to A-6 in Table 1 were produced using the same types and amounts of the constituent monomers, but by changing the amounts of mercaptoethanol as a chain transfer agent and ammonium persulfate as an initiator, to produce copolymers with different molecular weights.

[0103] In Table 1, the weight average molecular weight (Mw) and the ratio Mw / Mn of weight average molecular weight (Mw) to number average molecular weight (Mn) of each copolymer were measured by gel permeation chromatography (GPC) under the following conditions: *GPC conditions Apparatus: GPC (HLC-8320GPC) manufactured by Tosoh Corporation Column: G4000PWXL + G2500PWXL (manufactured by Tosoh Corporation) Eluent: 0.2 M phosphate buffer / CH ３CN = 9 / 1 Flow rate: 1.0 mL / min Column temperature: 40°C Detection: RI Sample size: 0.2 mg / mL Standard substance: Polyethylene glycol equivalent (monodisperse polyethylene glycol with known molecular weights, molecular weights 250,000, 145,000, 87,500, 46,000, and 24,000)

[0104] [Analysis of clay-containing gypsum] Natural gypsum (1) and natural gypsum (2) were used as clay-containing gypsum. The composition of natural gypsum (1) and natural gypsum (2) was analyzed by XRF analysis, and the silicon and phosphorus contents were quantified by ICP analysis. The measurement methods are as follows.

[0105] <XRF analysis> 50 mg of natural gypsum (1) was placed on filter paper, covered with PET film, and pressed to prepare a sample. The prepared sample was measured using an X-ray fluorescence analyzer under the following conditions. The results are shown in Table 2. Analysis device: Rigaku Corporation, wavelength dispersive X-ray fluorescence Prmus II 2θ (θ: analysis angle): varies depending on the measured element Target: rhodium tube Tube voltage: 50 kV Tube current: 50 mA Analyzing crystal: LiF (200), Ge, PET, RX25 Detector: SC, PC

[0106] <ICP analysis> The reagents used are as follows: sulfuric acid: precision analysis grade, Fujifilm Wako Pure Chemicals; hydrochloric acid: metal analysis grade, Kanto Chemical; nitric acid: EL grade, Kanto Chemical; hydrogen peroxide: atomic absorption spectrometry grade, Fujifilm Wako Pure Chemicals; sodium carbonate: special grade, Fujifilm Wako Pure Chemical Industries; boric acid: special grade, Fujifilm Wako Pure Chemical Industries; standard solutions of various elements: 1000 mg / L for atomic absorption spectrometry, Kanto Chemical; ultrapure water: water produced by ultrapure water production system Milli-Q, Millipore

[0107] 1. Sample Preparation (i) Pretreatment Method for Si: 0.1 g of sample was precisely weighed into a platinum crucible, and 2 g of alkaline flux (sodium carbonate:boric acid = 1:0.4) was added. The sample was then melted in an electric furnace at 950°C. A watch glass was placed over the sample, and 10 mL of ultrapure water and hydrochloric acid (6 mol / L) were added. The sample was heated and dissolved on a hot plate at 70-80°C. After cooling, the solution was adjusted to a constant volume of 100 mL with ultrapure water, and the resulting solution was used as the measurement solution. Values ​​outside the calibration curve range were appropriately diluted and used as the measurement solution. (ii) Pretreatment Method for P: 0.1 g of sample was placed in a decomposition vessel, and wet decomposition was performed by adding 2 mL of sulfuric acid, nitric acid, and hydrogen peroxide as needed. The volume was adjusted to a constant volume of 50 mL with ultrapure water, and the supernatant liquid, from which the insoluble matter was precipitated, was used as the sample measurement solution. (iii) Preparation of calibration curve solutions Calibration curve solutions of 0.1 to 20 mg / L were prepared using standard solutions for atomic absorption spectrometry (each element: 1000 mg / L). An alkaline flux and hydrochloric acid were added to the solution for Si determination so that the concentration was the same as that of the sample. Sulfuric acid was added to the solution for P determination so that the concentration was 4%.

[0108] 2. Measurement The sample prepared in 1. was subjected to measurement of each element using an ICP optical emission spectrometer under the following conditions. The results are shown in Table 2. Analyzer: Thermo Fisher Scientific iCAP6500Duo Wavelength: Si 251.611 nm, P 213.618 nm RF power: 1150 W Coolant gas flow rate: 12 L / min Nebulizer flow rate: 0.70 L / min Auxiliary gas: 0.5 L / min Pump flow rate: 50 rpm

[0109]

[0110] The values ​​obtained by XRF analysis are not quantitative values ​​but qualitative values ​​showing peak intensities.

[0111] <Methylene Blue Adsorption Test> The clay content of natural gypsum (1) and natural gypsum (2) was measured by the methylene blue adsorption test (JCAS I-61-2008) using the following method. The methylene blue adsorption test is commonly known as a method for measuring the active clay content in sand. The measurement principle involves titrating the amount of methylene blue adsorbed to the sand, and determining the degree of bleeding (halo) of the spot on the filter paper. The clay content of natural gypsum (1) was 4.93% by mass using the methylene blue adsorption test (JCAS I-61-2008). The clay content of natural gypsum (2) was 0.71% by mass using the methylene blue adsorption test (JCAS I-61-2008).

[0112] [Evaluation of Water Reducibility] A clay-containing gypsum slurry prepared by mixing natural gypsum (1) with water containing component (A) and / or component (B) was filled into a paste cone (diameter 50 mm x height 50 mm), which was then placed on a 30 cm x 30 cm plastic plate. 30 seconds after the natural gypsum (1) came into contact with water, the paste cone was lifted vertically, and the maximum diameter of the clay-containing gypsum slurry on the plastic plate and the diameter of the clay-containing gypsum slurry positioned perpendicular to the maximum diameter on the plastic plate were measured, and their average values ​​were calculated. Fluidity was defined as the amount of water at which the fluidity became 125 mm, and this was used as a standard to define a water reduction rate of 0%. The blending amount of the component (A) and / or the blending amount of the component (B) in the clay-containing gypsum slurry was set to the mass ratio (A) / [(A)+(B)] of the blending amount of the component (A) to the total blending amount of the component (A) and the component (B) shown in Table 3, and the total blending amount of the component (A) and the component (B) was changed to any blending amount shown in Table 3 per 100 parts by mass of gypsum. The water reduction rate was defined as the amount of water that could be reduced in the system, and measurements were performed. That is, for example, when a clay-containing gypsum slurry is prepared using only natural gypsum (1) (G) and water (W), and the amount of water required to achieve a fluidity of 125 mm is 200 g (W / G x 100 = 80% by mass), if the total amount of the (A) component and the (B) component is added to the clay-containing gypsum slurry in an amount of 0.256 parts by mass per 100 parts by mass of gypsum, and the amount of water required to achieve a fluidity of 125 mm is 160 g (W / G x 100 = 64% by mass), then 1-(160 / 200) = 0.2, and the water reduction rate is evaluated as 20%. The results are shown in Table 3. Furthermore, natural gypsum (1) was replaced with natural gypsum (2), and the same evaluation of water reduction as above was performed. The results are shown in Table 4.

[0113]

[0114]

[0115] In Tables 3 and 4, the mass ratio (A) / ((A)+(B)) and the blending amounts of the (A) component and the (B) component in the total blending amount per 100 parts by mass of gypsum are amounts based on the active ingredients. In Table 3, for the water reduction rate of Examples 1-8 to 1-13 where "not measured" is shown, the water reducing effect was confirmed in each example when the total added amount of (A) and (B) per 100 parts by mass of gypsum was 0.32 parts by mass and 0.48 parts by mass, and it can be inferred that the water reducing effect is also present when the total added amount of (A) and (B) per 100 parts by mass of gypsum was 0.16 parts by mass and 0.64 parts by mass, so measurement was not performed.

[0116] [Evaluation of Setting Property] 200 g of natural gypsum (1) and 120 g of water containing component (A) and / or component (B) were added to a 500 mL disposable cup so that the blending amounts of component (A) and component (B) per 100 parts by mass of gypsum were as shown in Table 4, and the mixture was stirred for 10 seconds at setting 3 (1500 rpm) using a hand mixer (MK-H4, manufactured by Panasonic Corporation) to prepare a clay-containing gypsum slurry. The setting time was measured for each clay-containing gypsum slurry prepared. The setting time refers to the time from adding water (water containing component (A) and / or component (B)) to natural gypsum (1) until setting, and the "initial time" and "final time" were measured as the setting progressed. The setting time was measured as follows. a) To measure the setting time, a Vicat needle apparatus specified in JIS R 5201 is used. The standard needle for gypsum slurries is a metal needle 45 mm long and 2 mm in diameter, with its head cut flat. The total mass of the moving part that descends with this needle is 300±1 g. b) The thermometer used is a thermometer with thermometer symbol C specified in JIS B 7411-1, or a temperature measuring device with equivalent or greater accuracy. c) The measurement method is to pour each prepared clay-containing gypsum slurry into a cylindrical mold with an inner diameter of 78±5 mm and a height of 40.0±0.5 mm placed on a glass plate, insert the thermometer into the center, and perform the following measurements. 1) Initial setting time: The time until the standard needle of the measuring device stops approximately 1 mm above the bottom of the test piece is measured. 2) Final setting time: The time until the thermometer indicates the maximum temperature is measured. The results are shown in Table 5. Furthermore, natural gypsum (1) was replaced with natural gypsum (2), and the same evaluation of setting property as above was carried out. The results are shown in Table 6. Table 7 shows formulation examples of clay-containing gypsum slurries. The clay-containing gypsum slurries of these formulation examples can shorten the setting time, similar to the clay-containing gypsum slurries of the examples in Tables 5 and 6.

[0117]

[0118]

[0119]

[0120] In Tables 5 to 7, the blending amounts of component (A) and component (B) are the blending amounts of component (A) and component (B) per 100 parts by mass of gypsum in the clay-containing gypsum slurry, which are effective amounts. Also, (A) / [(A)+(B)] (mass ratio) is the mass ratio (A) / ((A)+(B)) of the blending amount of component (A) in the clay-containing gypsum slurry to the combined blending amount of component (A) and component (B).

[0121] [Preparation of clay-containing gypsum slurry containing bubbles] A foaming agent composition containing 100% by mass of sodium decyl sulfate (C10AS) and sodium lauryl sulfate (C12AS) as component (C) in a mass ratio of C10AS / C12AS = 67 / 33 (mass%) was diluted with water to prepare an aqueous solution with a concentration of 0.6% by mass. 30 g of the prepared aqueous solution was added to a 1 L disposable cup, and the mixture was stirred for 60 seconds at 2000 rpm (EUROSTAR200 control, manufactured by IKA Japan Co., Ltd.) using a flat 6-paddle blade (FP-50, manufactured by AS ONE Corporation) to obtain a foam. 200 g of natural gypsum (1), 120 g of water to which the (A) component and / or (B) component were added, was added to a 500 mL disposable cup so that the blending amounts of the (A) component and (B) component relative to 100 parts by mass of gypsum were the blending amounts shown in Table 8, and a hand mixer (MK-H4, manufactured by Panasonic Corporation) was used to stir at memory 3 (1500 rpm) for 10 seconds to prepare a clay-containing gypsum slurry before adding foam. The entire amount of the prepared clay-containing gypsum slurry was added to 25 g of foam prepared in a 1 L disposable cup, and the 6-flat paddle blade was used in the 1 L disposable cup, and the mixture was kneaded at 1500 rpm for 30 seconds to obtain a clay-containing gypsum slurry containing bubbles.

[0122] [Measurement of average bubble diameter in gypsum] The obtained clay-containing gypsum slurry containing bubbles was poured into a mold for a cylindrical specimen (Plamold, manufactured by Nifco Corporation) with a diameter of 5 cm and a height of 10 cm and left to stand at room temperature for at least 1 hour. The hardened gypsum slurry was demolded from the mold for the cylindrical specimen and left to dry in a thermostatic bath at 60 ° C for 24 hours, and then a slit was made at a height of 5 cm to create a cross section of the hardened body. The cross section was observed with a digital microscope, and the diameters of 100 arbitrary bubble cross sections were measured, and the average bubble diameter was calculated from the arithmetic average of these values. Note that the diameter of the bubble cross section was measured as the diameter if the bubble cross section was circular, the major axis if the bubble cross section was elliptical, and the longest part if the bubble cross section was irregular. The results are shown in Table 8. The specific gravity of the obtained gypsum hardened bodies of the examples and comparative examples was all about 0.5. In addition, natural gypsum (1) was replaced with natural gypsum (2), and a clay-containing gypsum slurry containing bubbles was prepared in the same manner as above, and the average bubble diameter in the gypsum was measured. The results are shown in Table 9. Table 10 also shows formulation examples of clay-containing gypsum slurries containing bubbles, similar to Tables 8 and 9. The clay-containing gypsum slurries containing bubbles of these formulation examples, like the clay-containing gypsum slurries containing bubbles in the examples of Tables 8 and 9, can have a larger average bubble diameter in the gypsum hardened body than the comparative examples of Tables 8 and 9.

[0123]

[0124]

[0125]

[0126] In Tables 8 to 10, the blending amounts of component (A) and component (B) are the blending amounts of component (A) and component (B) per 100 parts by mass of gypsum in the clay-containing gypsum slurry containing bubbles, and are effective amounts. Also, (A) / [(A)+(B)] (mass ratio) is the mass ratio (A) / ((A)+(B)) of the blending amount of component (A) in the clay-containing gypsum slurry containing bubbles to the combined blending amount of component (A) and component (B).

Claims

1. A clay-containing gypsum slurry containing the following component (A), gypsum containing clay, and water: Component (A): A copolymer containing, as constituent monomers, a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2), in which the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) is less than 5 mass%, and the weight average molecular weight is 50,000 or more and 250,000 or less. [In the formula, R １ａ , R ２ａ , R ３ａ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ａ (CH ２ ) ｒ COOM ２ａ is COOM １ａ or other (CH ２ ) ｒ COOM ２ａ When forming an anhydride with the M １ａ , M. ２ａ does not exist. １ａ , M. ２ａ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ａ , R ５ａ R: the same or different, a hydrogen atom or a methyl group ６ａ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ１ (CO) ｐ１ O (AO) ｎ１ R ７a R ７ａ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n1: the average number of moles of AO added, which is a number of from 100 to 150; q1: a number of from 0 to 6; p1: 0 or 1; M ３ａ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

2. The clay-containing gypsum slurry according to claim 1, wherein the clay content of the gypsum containing the clay is 0.5% by mass or more and 6.0% by mass or less according to a methylene blue adsorption test (JCAS I-61-2008).

3. The clay-containing gypsum slurry according to claim 1 or 2, further comprising the following component (B): Component (B): a copolymer containing, as constituent monomers, a constituent monomer (B1) represented by the following general formula (B1) and a constituent monomer (B2) represented by the following general formula (B2), in which the proportion of the constituent monomer (B1) in the total amount of the constituent monomer (B1) and the constituent monomer (B2) is 5% by mass or more and less than 13% by mass. [In the formula, R １ｂ , R ２ｂ , R ３ｂ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ｂ (CH ２ ) ｒ COOM ２ｂ is COOM １ｂ or other (CH ２ ) ｒ COOM ２ｂ When forming an anhydride with the M １ｂ , M. ２ｂ does not exist. １ｂ , M. ２ｂ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ｂ , R ５ｂ R: the same or different, a hydrogen atom or a methyl group ６ｂ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ｂ , or (CH ２ ) ｑ２ (CO) ｐ２ O (AO) ｎ２ R ７ｂ R ７ｂ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n2: the average number of moles of AO added, which is a number of from 5 to 300; q2: a number of from 0 to 6; p2: 0 or 1; M ３ｂ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

4. The clay-containing gypsum slurry according to claim 3, wherein the mass ratio (A) / ((A)+(B)) of the content of the (A) component to the total content of the (A) component and the (B) component is 0.2 or more.

5. The clay-containing gypsum slurry according to claim 3 or 4, wherein the component (B) is a copolymer in which n2 in general formula (B2) is 50 or more and 150 or less.

6. The clay-containing gypsum slurry according to any one of claims 1 to 5, further comprising a foaming agent as component (C).

7. A method for producing a clay-containing gypsum slurry, comprising the following steps 1 and 2. <Step 1> A step of foaming a liquid composition containing a foaming agent (C) and water to obtain a foam. <Step 2> A step of mixing a dispersant for clay-containing gypsum slurry containing the following component (A), gypsum containing clay, water, and the foam obtained in step 1. Component (A): A copolymer containing, as constituent monomers, a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2), in which the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) is less than 5 mass%, and the copolymer has a weight average molecular weight of 50,000 or more and 250,000 or less. [In the formula, R １ａ , R ２ａ , R ３ａ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ａ (CH ２ ) ｒ COOM ２ａ is COOM １ａ or other (CH ２ ) ｒ COOM ２ａ When forming an anhydride with the M １ａ , M. ２ａ does not exist. １ａ , M. ２ａ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ａ , R ５ａ R: the same or different, a hydrogen atom or a methyl group ６ａ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ１ (CO) ｐ１ O (AO) ｎ１ R ７a R ７ａ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n1: the average number of moles of AO added, which is a number of from 100 to 150; q1: a number of from 0 to 6; p1: 0 or 1; M ３ａ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

8. The method for producing a clay-containing gypsum slurry according to claim 7, wherein the clay-containing gypsum slurry dispersant further contains the following component (B): Component (B): a copolymer containing, as constituent monomers, a constituent monomer (B1) represented by the following general formula (B1) and a constituent monomer (B2) represented by the following general formula (B2), in which the proportion of the constituent monomer (B1) in the total amount of the constituent monomer (B1) and the constituent monomer (B2) is 5 mass% or more and less than 13 mass%. [In the formula, R １ｂ , R ２ｂ , R ３ｂ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ｂ (CH ２ ) ｒ COOM ２ｂ is COOM １ｂ or other (CH ２ ) ｒ COOM ２ｂ When forming an anhydride with the M １ｂ , M. ２ｂ does not exist. １ｂ , M. ２ｂ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ｂ , R ５ｂ R: the same or different, a hydrogen atom or a methyl group ６ｂ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ｂ , or (CH ２ ) ｑ２ (CO) ｐ２ O (AO) ｎ２ R ７ｂ R ７ｂ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n2: the average number of moles of AO added, which is a number of from 5 to 300; q2: a number of from 0 to 6; p2: 0 or 1; M ３ｂ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

9. The method for producing a clay-containing gypsum slurry according to claim 7 or 8, wherein in step 1, the liquid composition is foamed at a foaming ratio of 5 to 30 times to obtain a foam.

10. A method for producing a hardened body of a clay-containing gypsum slurry according to any one of claims 7 to 9, further comprising carrying out the following step 3 after step 2. <Step 3> A step of forming and hardening the clay-containing gypsum slurry obtained by step 2.

11. Use of a dispersant containing the following component (A) in a clay-containing gypsum slurry: Component (A): A copolymer containing, as constituent monomers, a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2), in which the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) is less than 5 mass%, and the weight average molecular weight is 50,000 or more and 250,000 or less. [In the formula, R １ａ , R ２ａ , R ３ａ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ａ (CH ２ ) ｒ COOM ２ａ is COOM １ａ or other (CH ２ ) ｒ COOM ２ａ When forming an anhydride with the M １ａ , M. ２ａ does not exist. １ａ , M. ２ａ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ａ , R ５ａ R: the same or different, a hydrogen atom or a methyl group ６ａ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ１ (CO) ｐ１ O (AO) ｎ１ R ７a R ７ａ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n1: the average number of moles of AO added, which is a number of from 100 to 150; q1: a number of from 0 to 6; p1: 0 or 1; M ３ａ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

12. Use of the dispersant according to claim 11 in a clay-containing gypsum slurry, further comprising the following component (B): Component (B): a copolymer containing, as constituent monomers, a constituent monomer (B1) represented by the following general formula (B1) and a constituent monomer (B2) represented by the following general formula (B2), in which the proportion of the constituent monomer (B1) in the total amount of the constituent monomers (B1) and (B2) is 5% by mass or more and less than 13% by mass. [In the formula, R １ｂ , R ２ｂ , R ３ｂ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ｂ (CH ２ ) ｒ COOM ２ｂ is COOM １ｂ or other (CH ２ ) ｒ COOM ２ｂ When forming an anhydride with the M １ｂ , M. ２ｂ does not exist. １ｂ , M. ２ｂ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ｂ , R ５ｂ R: the same or different, a hydrogen atom or a methyl group ６ｂ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ｂ , or (CH ２ ) ｑ２ (CO) ｐ２ O (AO) ｎ２ R ７ｂ R ７ｂ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n2: the average number of moles of AO added, which is a number of from 5 to 300; q2: a number of from 0 to 6; p2: 0 or 1; M ３ｂ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

13. Use of the dispersant according to claim 12 in a clay-containing gypsum slurry, wherein the mass ratio (A) / ((A)+(B)) of the content of the component (A) to the total content of the components (A) and (B) is 0.2 or more.

14. Use of the dispersant according to claim 12 or 13 in a clay-containing gypsum slurry, wherein the content of component (B) is 20% by mass or more and 60% by mass or less.

15. Use of the dispersant according to any one of claims 12 to 15 in a clay-containing gypsum slurry, wherein the component (B) is a copolymer in which n2 in general formula (B2) is 50 or more and 150 or less.

16. A method for improving the water reducibility of a clay-containing gypsum slurry, comprising mixing a dispersant for clay-containing gypsum slurry, containing the following component (A), with the clay-containing gypsum slurry: Component (A): A copolymer containing, as constituent monomers, a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2), in which the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) is less than 5 mass%, and the copolymer has a weight average molecular weight of 50,000 or more and 250,000 or less. [In the formula, R １ａ , R ２ａ , R ３ａ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ａ (CH ２ ) ｒ COOM ２ａ is COOM １ａ or other (CH ２ ) ｒ COOM ２ａ When forming an anhydride with the M １ａ , M. ２ａ does not exist. １ａ , M. ２ａ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ａ , R ５ａ R: the same or different, a hydrogen atom or a methyl group ６ａ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ１ (CO) ｐ１ O (AO) ｎ１ R ７a R ７ａ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n1: the average number of moles of AO added, which is a number of from 100 to 150; q1: a number of from 0 to 6; p1: 0 or 1; M ３ａ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

17. The method for improving the water reducing property of a clay-containing gypsum slurry according to claim 16, wherein the dispersant further contains the following component (B): Component (B): a copolymer containing, as constituent monomers, a constituent monomer (B1) represented by the following general formula (B1) and a constituent monomer (B2) represented by the following general formula (B2), wherein the proportion of the constituent monomer (B1) in the total amount of the constituent monomer (B1) and the constituent monomer (B2) is 5 mass% or more and less than 13 mass%. [In the formula, R １ｂ , R ２ｂ , R ３ｂ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ｂ (CH ２ ) ｒ COOM ２ｂ is COOM １ｂ or other (CH ２ ) ｒ COOM ２ｂ When forming an anhydride with the M １ｂ , M. ２ｂ does not exist. １ｂ , M. ２ｂ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ｂ , R ５ｂ R: the same or different, a hydrogen atom or a methyl group ６ｂ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ｂ , or (CH ２ ) ｑ２ (CO) ｐ２ O (AO) ｎ２ R ７ｂ R ７ｂ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n2: the average number of moles of AO added, which is a number of from 5 to 300; q2: a number of from 0 to 6; p2: 0 or 1; M ３ｂ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

18. An additive kit for clay-containing gypsum slurry, comprising a first agent containing the following component (A) and a second agent containing a foaming agent (C): Component (A): a copolymer containing, as constituent monomers, a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2), in which the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) is less than 5 mass%, and the weight average molecular weight is 50,000 or more and 250,000 or less. [In the formula, R １ａ , R ２ａ , R ３ａ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ａ (CH ２ ) ｒ COOM ２ａ is COOM １ａ or other (CH ２ ) ｒ COOM ２ａ When forming an anhydride with the M １ａ , M. ２ａ does not exist. １ａ , M. ２ａ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ａ , R ５ａ R: the same or different, a hydrogen atom or a methyl group ６ａ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ１ (CO) ｐ１ O (AO) ｎ１ R ７a R ７ａ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n1: the average number of moles of AO added, which is a number of from 100 to 150; q1: a number of from 0 to 6; p1: 0 or 1; M ３ａ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

19. The clay-containing gypsum slurry additive kit according to claim 18, wherein the first agent further contains the following component (B): Component (B): a copolymer containing, as constituent monomers, a constituent monomer (B1) represented by the following general formula (B1) and a constituent monomer (B2) represented by the following general formula (B2), wherein the proportion of the constituent monomer (B1) in the total amount of the constituent monomer (B1) and the constituent monomer (B2) is 5 mass% or more and less than 13 mass%. [In the formula, R １ｂ , R ２ｂ , R ３ｂ : the same or different, each of which is a hydrogen atom, a methyl group, or (CH ２ ) ｒ COOM ２ｂ (CH ２ ) ｒ COOM ２ｂ is COOM １ｂ or other (CH ２ ) ｒ COOM ２ｂ When forming an anhydride with the M １ｂ , M. ２ｂ does not exist. １ｂ , M. ２ｂ : are the same or different and each represents a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group, or an alkenyl group; and r is a number of 0 to 2. [In the formula, R ４ｂ , R ５ｂ R: the same or different, a hydrogen atom or a methyl group ６ｂ : hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ｂ , or (CH ２ ) ｑ２ (CO) ｐ２ O (AO) ｎ２ R ７ｂ R ７ｂ AO: an alkyleneoxy group having from 2 to 4 carbon atoms; n2: the average number of moles of AO added, which is a number of from 5 to 300; q2: a number of from 0 to 6; p2: 0 or 1; M ３ｂ : a hydrogen atom, an alkali metal, an alkaline earth metal (1 / 2 atom), an ammonium group, an alkylammonium group, a substituted alkylammonium group, an alkyl group, a hydroxyalkyl group or an alkenyl group, and r: a number of 0 to 2.

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