Dispersant for clay-containing gypsum slurry

Abstract

To provide a dispersing agent for clay-containing gypsum slurry, capable of imparting excellent water-reducing properties to gypsum slurry even when a clay-containing gypsum is used, and capable of enlarging a bubble diameter in the gypsum hardened body when the gypsum slurry contains bubbles, and to provide the clay-containing gypsum slurry, having the excellent water-reducing properties even when the clay-containing gypsum is used, and having the large bubble diameter in the gypsum hardened body when the gypsum slurry contains the bubbles.SOLUTION: A dispersant for clay-containing gypsum slurry comprises the following component (A). Component (A): A copolymer comprising a constituent monomer (A1) represented by general formula (A1), a constituent monomer (A2) represented by a specific formula 2, and a cross-linking monomer (A3) as constituent monomers, wherein a ratio of the monomer (A1) to the total amount of the monomers (A1) and (A2) is 1 mass% or more but less than 10 mass%, and a weight average molecular weight is 80,000 or more but 250000 or less.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In the gypsum slurry used for gypsum boards, naphthalenesulfonic acid formaldehyde condensates have been used as dispersants. In recent years, the use of polycarboxylic acid-based dispersants has been increasing from the viewpoint of reducing production costs. When manufacturing gypsum boards, the gypsum slurry is formed into a plate and then dried in a dryer to remove excess water, but by using a polycarboxylic acid dispersant with high water-reducing properties, it is possible to form the board with a small amount of water, which has the advantage of reducing drying costs. LPG, LNG, coal, oil, etc. are used as fuel for the dryer, but with the recent rise in fuel prices, the benefits of using polycarboxylic acid dispersants are increasing.

[0003] Patent Document 1 discloses a dispersant for a clay-containing hydraulic composition, which contains components (A), (B), and (C) that are 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 component (A) and component (B) to the total content of component (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. Patent Document 2 discloses a cement admixture characterized by comprising a copolymer obtained by polymerizing the monomers shown in (1) and (2) below and / or a metal salt of the copolymer. (1) Polyalkylene glycol diester monomers having unsaturated bonds (2) Monomers with dissociable groups Patent Document 3 discloses a cement admixture containing, as its main component, a crosslinked polymer obtained by copolymerizing a monomer selected from diepoxy compounds, a monomer selected from polyalkylene compounds, and a monomer selected from acrylic acid monomers and unsaturated dicarboxylic acid monomers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-018729 [Patent Document 2] Japanese Patent Application Publication No. 5-238795 [Patent Document 3] Japanese Patent Application Publication No. 6-157100 Summary of the Invention [Problem to be solved by the invention]

[0005] Examples of gypsum used in the gypsum slurry include natural gypsum and by-product gypsum such as flue gas desulfurization gypsum, and in recent years, inexpensive natural gypsum has come to be used. However, natural gypsum contains clay and varies in quality, and the inventors have found that when natural gypsum and a polycarboxylic acid-based dispersant are used in a gypsum slurry, the water reducing ability of the gypsum slurry is significantly reduced, and the advantage of reducing drying costs by enabling molding with a small amount of water cannot be obtained. Furthermore, the present inventors have found that when the gypsum slurry contains air bubbles, since a polycarboxylic acid-based dispersant has a property of stabilizing the bubbles, if a large amount is used, the air bubbles in the gypsum slurry do not break or coalesce, resulting in a problem that the air bubble diameter after the gypsum slurry hardens is small and the strength of the gypsum hardened body is reduced.

[0006] The present invention provides a dispersant for clay-containing gypsum slurry that can impart excellent water reducing property to a gypsum slurry even when gypsum containing clay is used, and can increase the air bubble diameter in the gypsum hardened body when the gypsum slurry contains air bubbles, and provides a clay-containing gypsum slurry that has excellent water reducing property even when gypsum containing clay is used, and has a large air bubble diameter in the gypsum hardened body when the gypsum slurry contains air bubbles. [Means for solving the problem]

[0007] The present invention relates to a dispersant for a clay-containing gypsum slurry, 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), a constituent monomer (A2) represented by the following general formula (A2), and a crosslinkable monomer (A3), in which the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) is 1% by mass or more and less than 10% by mass, and the weight average molecular weight is 80,000 or more and 250,000 or less.

[0008] [ka]

[0009] [During the ceremony, 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 COOM 1a or other (CH 2 ) r COOM 2a When forming an anhydride with the M 1a , M 2a does not exist. M 1a , M 2a: The same or different, 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 r: A number from 0 to 2 represents. ]

[0010] [Chemical formula]

[0011] [In the formula, R 4a , R 5a : The same or different, a hydrogen atom or a methyl group R 6a : A hydrogen atom, a 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 addition of AO, a number from 5 to 150 q1: A number from 0 to 6 p1: 0 or 1 M 3a : The same as defined in r: A number from 0 to 2 represents. ]

[0012] The present invention also relates to a clay-containing gypsum slurry containing the component (A), gypsum containing clay, and water. [Advantages of the Invention]

[0013] According to the present invention, a dispersant for clay-containing gypsum slurry is provided which can impart excellent water reducing property to a gypsum slurry even when gypsum containing clay is used, and can increase the air bubble diameter in the gypsum hardened body when the gypsum slurry contains air bubbles, and a clay-containing gypsum slurry is provided which has excellent water reducing property even when gypsum containing clay is used, and has a large air bubble diameter in the gypsum hardened body when the gypsum slurry contains air bubbles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The reason why the clay-containing gypsum slurry dispersant of the present invention can impart excellent water reducing properties to the gypsum slurry even when gypsum containing clay is used, and can increase the bubble diameter in the gypsum hardened body when the gypsum slurry contains bubbles is not necessarily clear, but is presumed as follows. When gypsum containing clay is used in the gypsum slurry, it is presumed that the gypsum and the clay have different charges and undergo hetero-aggregation, so that the gypsum holds free water and the water reducing properties are reduced. It is also presumed that when a polycarboxylic acid dispersant is used in the clay-containing gypsum slurry, the alkyleneoxy chain introduced as a steric repulsive group of the polymer, which is the polycarboxylic acid dispersant, is adsorbed to the clay, so that it cannot be efficiently adsorbed to the gypsum, and the water reducing properties are reduced. In the present invention, it is presumed that by deliberately using a specific polycarboxylic acid dispersant, which is the component (A) that is easily adsorbed to clay, the characteristics of the component (A) that is originally adsorbed and dispersed in gypsum and other polycarboxylic acid dispersants (preferably the component (B)) can be efficiently acted on to impart excellent water reducing properties to the gypsum slurry. 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, and therefore 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.

[0015] [Dispersant for clay-containing gypsum slurry] <Component (A)> The clay-containing gypsum slurry dispersant 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), a constituent monomer (A2) represented by the following general formula (A2), and a crosslinkable monomer (A3), wherein the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) is 1 mass % or more and less than 10 mass %, and the weight average molecular weight is 80,000 or more and 250,000 or less.

[0016] [ka]

[0017] [During the ceremony, 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 COOM 1a or other (CH 2 ) r COOM 2a When forming an anhydride with the M 1a , M 2a does not exist. M 1a , M 2a : the same or different, 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. r: A number between 0 and 2 Indicates the following.

[0018] [ka]

[0019] [During the ceremony, R 4a , R 5a : Same or different, hydrogen atom or methyl group R 6a : Hydrogen atom, methyl group, (CH 2 ) r COOM 3a , or (CH 2 ) q1 (CO) p1 O(AO) n1 R 7a R 7a : 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, a number between 5 and 150 q1: A number between 0 and 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 between 0 and 2 Indicates the following.

[0020] In the general formula (A1), from the viewpoint of availability, R 1a is preferably a hydrogen atom. 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, and more preferably a methyl group. In the general formula (A1), from the viewpoint of availability, R 3a is preferably a hydrogen atom. (CH 2 ) r COOM 2a About COOM 1a or other (CH 2 ) r COOM 2a and an anhydride may be formed, in which case, M 1a , M 2a does not exist. M1a and M. 2a are the same or different and each is 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. M 1a and M. 2a The alkyl group, the hydroxyalkyl group, and the alkenyl group each preferably have 1 to 4 carbon atoms. M 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, even 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. (CH 2 ) r COOM 2a In the formula, r is preferably 0.

[0021] In general formula (A2), R 4a is preferably a hydrogen atom from the viewpoint of availability. In general formula (A2), R 5a From the viewpoints of availability and copolymerizability with the constituent monomer (A1), is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. In general formula (A2), R 6a is preferably a hydrogen atom from the viewpoint of availability. In general formula (A2), R 7a From the viewpoints of ease of production and quality stability of the product, is preferably a hydrogen atom or a methyl group, and more preferably a methyl group. In the 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 the general formula (A2), n1 is the average number of moles of AO added, and from the viewpoint of improving the water reducing property of the clay-containing gypsum slurry and increasing the bubble diameter in the gypsum hardened body, it is 5 or more, preferably 50 or more, more preferably 100 or more, and 150 or less, preferably 140 or less, more preferably 130 or less. In addition, when AO contains alkyleneoxy groups with different carbon numbers in the average n1 repeating units, these alkyleneoxy groups with different carbon numbers may include random addition or block addition or a mixture of these. In the total AO, the ethyleneoxy group is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, and it is further preferable that the total AO is an ethyleneoxy group. For example, AO can also contain a propyleneoxy group, a butyleneoxy group, etc. in addition to an ethyleneoxy group. In formula (A2), from the viewpoint of availability, q1 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0. (CH 2 ) r COOM 3a M 3a A preferred embodiment of the formula is M 1a , M 2a and r is preferably 0.

[0022] The crosslinkable monomer (A3) may be at least one selected from the group consisting of crosslinkable monomers having two or more epoxy groups and crosslinkable monomers having two or more vinyl groups.

[0023] From the viewpoint of controlling the crosslinking reaction, the crosslinkable monomer (A3) is preferably a crosslinkable monomer having two or more epoxy groups, and more preferably a monomer represented by the following general formula (A3).

[0024] [ka]

[0025] [During the ceremony, R 8a : an alkylene group having 2 to 4 carbon atoms m: An integer between 1 and 30 is shown.

[0026] In general formula (A3), R 8a is preferably an ethylene group from the viewpoint of productivity, and preferably a butylene group from the viewpoints of improving the water-reducing property of the clay-containing gypsum slurry and increasing the bubble diameter in the gypsum hardened body. In general formula (A3), m is an integer of 1 or more, and 30 or less, preferably 20 or less, more preferably 15 or less, and still more preferably 10 or less, from the viewpoints of reactivity, improving the water-reducing property of the clay-containing gypsum slurry, and increasing the bubble diameter in the gypsum hardened body.

[0027] Examples of the crosslinkable monomer having two or more vinyl groups include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, decaethylene glycol di(meth)acrylate, pentadecaethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, glycerin di(meth)acrylate, allyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, phthalic acid diethylene glycol di(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified hydroxypivalic acid ester neopentyl glycol di(meth)acrylate, polyester (meth)acrylate, urethane (meth)acrylate and other (meth)acrylic acid ester-based crosslinkable monomers, divinylbenzene, divinylnaphthalene and aromatic divinyl-based monomers such as derivatives thereof. These may be used alone or in combination of two or more.

[0028] Of all the constituent monomers of the component (A), the proportion of the constituent monomer (A1) in the total amount of the constituent monomer (A1) and the constituent monomer (A2) is, from the viewpoints of crosslinking reactivity with the crosslinkable monomer (A3) and storage stability, preferably 1 mass % or more, more preferably 2 mass % or more, even more preferably 3 mass % or more, and is less than 10 mass %, preferably 9 mass % or less, more preferably 8 mass % or less.

[0029] Of all the constituent monomers of the component (A), the proportion of the constituent monomer (A1) in the total amount of the constituent monomer (A1) and the constituent monomer (A2) is, from the viewpoints of crosslinking reactivity with the crosslinkable monomer (A3) and storage stability, preferably 60 mol % or more, more preferably 65 mol % or more, even more preferably 70 mol % or more, and preferably 85 mol % or less, more preferably 83 mol % or less, even more preferably 81 mol % or less.

[0030] Of all the constituent monomers of the component (A), the proportion of the constituent monomer (A2) in the total amount of the constituent monomer (A1) and the constituent monomer (A2) is, from the viewpoints of adsorption to clay and crosslinking reactivity with the crosslinkable monomer (A3), preferably 92 mass% or more, more preferably 93 mass% or more, even more preferably 94 mass% or more, and preferably 99 mass% or less, preferably 98 mass% or less, more preferably 97.5 mass% or less.

[0031] Of all the constituent monomers of the component (A), the proportion of the constituent monomer (A2) in the total amount of the constituent monomer (A1) and the constituent monomer (A2) is, from the viewpoints of adsorption to clay and crosslinking reactivity with the crosslinkable monomer (A3), preferably 15 mol% or more, more preferably 17 mol% or more, even more preferably 19 mol% or more, and preferably 40 mol% or less, more preferably 35 mol% or less, even more preferably 30 mol% or less.

[0032] Of all the constituent monomers of the component (A), the total amount of the constituent monomer (A1) and the constituent monomer (A2) is preferably 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, and preferably 99 mass% or less, from the viewpoints of improving the water reducing property of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body. Of all the constituent monomers of the component (A), the total amount of the constituent monomer (A1) and the constituent monomer (A2) is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 90 mol % or more, and preferably 99 mol % or less, from the viewpoints of improving the water reducing property of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body.

[0033] The proportion of the crosslinkable monomer (A3) in all the constituent monomers of the component (A), relative to the total amount (100 mass%) of the constituent monomers (A1) and (A2), is preferably 0.5 mass% or more, more preferably 1.0 mass% or more, and even more preferably 1.5 mass% or more, from the viewpoint of crosslinking reactivity, and is preferably 20 mass% or less, more preferably 15 mass% or less, and even more preferably 10 mass% or less, from the viewpoint of suppressing gelation.

[0034] In the component (A), the crosslinking rate (%) of the crosslinkable monomer (A3) is preferably 5% or more, more preferably 10% or more, and even more preferably 20% or more, from the viewpoint of crosslinking reactivity, and is preferably 300% or less, more preferably 200% or less, even more preferably 150% or less, and even more preferably 120% or less, from the viewpoint of suppressing gelation. The crosslinking rate (%) of the crosslinkable monomer (A3) is calculated by the following formula (1). Crosslinking rate (%)=[molecular weight of constituent monomer (A1) / proportion (by mass) of (A1) in the constituent monomers of component (A)]×[proportion (by mass) of crosslinkable monomer (A3) in component (A) / epoxy equivalent of crosslinkable monomer (A3)]×100 (Equation 1) In formula (1), the proportion (mass %) of the constituent monomer (A1) is the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) among all the constituent monomers of the component (A), and the proportion (mass %) of the crosslinkable monomer (A3) is the proportion (mass %) of the crosslinkable monomer (A3) with respect to the total amount (100 mass %) of the constituent monomers (A1) and (A2) among all the constituent monomers of the component (A).

[0035] The copolymer of the component (A) may contain a constituent monomer other than the constituent monomer (A1), the constituent monomer (A2), and the crosslinkable monomer (A3) [hereinafter also referred to as the constituent monomer (A4)]. Examples of the constituent monomer (A4) include hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-(methacryloyloxy)ethyl phosphate (HEMA-P), 2-hydroxyethyl acrylate (HEA), methyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate (HEMA), allyl sulfonic acid, methallyl sulfonic acid, and salts thereof, such as alkali metal salts, alkaline earth metal salts, ammonium salts, or amine salts. Further, structural units using one or more monomers selected from (meth)acrylamide, N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, 2-(meth)acrylamide-2-methanesulfonic acid, 2-(meth)acrylamide-2-ethanesulfonic acid, 2-(meth)acrylamide-2-propanesulfonic acid, styrene, styrene sulfonic acid, etc. can be mentioned. (Meth)acryl means acryl or methacryl.

[0036] From the viewpoint of the adsorptivity to clay, 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, still more preferably 120,000 or more, and 250,000 or less, preferably 230,000 or less, more preferably 200,000 or less, still more preferably 180,000 or less.

[0037] The weight average molecular weight of the component (A) was measured by gel permeation chromatography (GPC) under the following conditions. *GPC conditions Equipment: GPC (HLC-8320GPC) manufactured by Tosoh Corporation Column: G4000PWXL+G2500PWXL (Tosoh Corporation) Eluent: 0.2M phosphate buffer / CH 3 CN=9 / 1 Flow rate: 1.0mL / min Column temperature: 40℃ Detection: RI Sample size: 0.2mg / mL Standard substance: Polyethylene glycol equivalent (monodisperse polyethylene glycol with known molecular weight, molecular weight 87,500, 250,000, 145,000, 46,000, 24,000)

[0038] The content of the (A) component in the dispersant for a clay-containing gypsum slurry of the present invention is, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body, preferably 20 mass % or more, more preferably 25 mass % or more, even more preferably 30 mass % or more, and preferably 60 mass % or less, more preferably 50 mass % or less, and even more preferably 40 mass % or less.

[0039] <(B) component> From the viewpoints of improving the water reducibility of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body, the dispersant for clay-containing gypsum slurry 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 1 mass% or more and less than 17 mass%.

[0040] [ka]

[0041] [During the ceremony, 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 COOM 1b or other (CH 2 ) r COOM 2b When forming an anhydride with the M 1b , M 2b does not exist. M 1b , M 2b : the same or different, 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. r: A number between 0 and 2 Indicates the following.

[0042] [ka] [During the ceremony, R 4b , R 5b : Same or different, hydrogen atom or methyl group R 6b : Hydrogen atom, methyl group, (CH 2 ) r COOM 3b , or (CH 2 ) q2 (CO) p2 O(AO) n2 R 7b R 7b : 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, a number of 5 to 300 q2: A number between 0 and 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 between 0 and 2 Indicates the following.

[0043] In the general formula (B1), from the viewpoint of availability, R 1b is preferably a hydrogen atom. 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, and more preferably a methyl group. In the general formula (B1), from the viewpoint of availability, R 3b is preferably a hydrogen atom. (CH 2 ) r COOM 2b About COOM 1b or other (CH 2 ) r COOM 2b and an anhydride may be formed, in which case, M 1b , M 2b does not exist. M 1b and M. 2b are the same or different and each is 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. M 1b and M. 2b The alkyl group, the hydroxyalkyl group, and the alkenyl group each preferably have 1 to 4 carbon atoms. M 1b and M. 2bis the same or different and is 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 even more preferably a hydrogen atom or an alkali metal. In general formula (B1), (CH 2 ) r COOM 2b r is preferably 0.

[0044] In general formula (B2), R 4b is preferably a hydrogen atom from the viewpoint of availability. In general formula (B2), R 5b is preferably a hydrogen atom or a methyl group from the viewpoints of availability and copolymerizability with the constituent monomer (B1), and more preferably a methyl group. In general formula (B2), R 6b is preferably a hydrogen atom from the viewpoint of availability. In general formula (B2), R 7b is preferably a hydrogen atom or a methyl group from the viewpoints of ease of production and quality stability of the product, and more preferably a methyl group. In general formula (B2), AO is preferably a group selected from an ethyleneoxy group and a propyleneoxy group from the viewpoints of availability and price, and more preferably an ethyleneoxy group. AO preferably contains an ethyleneoxy group. In the general formula (B2), n2 is the average number of moles of AO added, and from the viewpoint of improving the water reducing property of the clay-containing gypsum slurry and increasing the bubble diameter in the gypsum hardened body, it is 5 or more, preferably 20 or more, more preferably 30 or more, even more preferably 50 or more, even more preferably 80 or more, even more preferably 100 or more, and 300 or less, preferably 150 or less, more preferably 130 or less. In addition, when AO contains alkyleneoxy groups with different carbon numbers in the average n2 repeating units, these alkyleneoxy groups with different carbon numbers may include random addition or block addition or a mixture of these. In the total AO, the ethyleneoxy group is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and it is preferable that all AO are ethyleneoxy groups. For example, AO can also contain propyleneoxy groups, butyleneoxy groups, etc. in addition to ethyleneoxy groups. In general formula (B2), q2 is preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 0, from the viewpoint of availability. (CH 2 ) r COOM 3b M 3b A preferred embodiment of the formula is M 1b , M 2b and r is preferably 0.

[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, from the viewpoints of improving the water reducing property of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body, 1 mass % or more, preferably 3 mass % or more, more preferably 5 mass % or more, and less than 17 mass %, preferably 15 mass % or less, more preferably 13 mass % or less.

[0046] 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, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body, preferably 60 mol % or more, more preferably 70 mol % or more, even more preferably 80 mol % or more, and preferably 95 mol % or less, more preferably 90 mol % or less, even more preferably 85 mol % or less.

[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, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body, preferably 83 mass% or more, more preferably 85 mass% or more, even more preferably 87 mass% or more, and preferably 99 mass% or less, preferably 97 mass% or less, and more preferably 95 mass% or less.

[0048] 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, from the viewpoints of improving the water reducing property of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body, preferably 5 mol % or more, more preferably 10 mol % or more, even more preferably 15 mol % or more, and preferably 40 mol % or less, more preferably 30 mol % or less, and even more preferably 20 mol % or less.

[0049] Of all the constituent monomers of the component (B), the total amount of the constituent monomer (B1) and the constituent monomer (B2) is preferably 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, and preferably 100 mass% or less, from the viewpoints of improving the water reducing property of the clay-containing gypsum slurry and increasing the bubble diameter in the gypsum hardened body. This total amount may be 100 mass%. Of all the constituent monomers of the component (B), the total amount of the constituent monomers (B1) and (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 viewpoint of improving the water reducing property of the clay-containing gypsum slurry and increasing the bubble diameter in the gypsum hardened body. This total amount may be 100 mol%.

[0050] The copolymer of component (B) may contain a constituent monomer other than the constituent monomers (B1) and (B2) (hereinafter also referred to as constituent monomer (B3)). Examples of the 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.

[0051] From the viewpoints of improving the water reducing property of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body, the weight average molecular weight of the (B) component is preferably 40,000 or more, more preferably 45,000 or more, even more preferably 50,000 or more, and preferably 80,000 or less, more preferably 75,000 or less, even more preferably 70,000 or less. The weight average molecular weight of component (B) is measured by gel permeation chromatography (GPC) under the same conditions as those described for component (A).

[0052] 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 mass % or more, more preferably 25 mass % or more, even more preferably 30 mass % or more, and preferably 60 mass % or less, more preferably 55 mass % or less, and even more preferably 50 mass % or less, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body.

[0053] 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, from the viewpoints of improving the water reducibility of the clay-containing gypsum slurry and increasing the air bubble diameter in the gypsum hardened body, preferably 0.15 or more, more preferably 0.2 or more, even more preferably 0.25 or more, still more preferably 0.3 or more, and preferably 0.8 or less, more preferably 0.7 or less, even more preferably 0.65 or less, and still more preferably 0.6 or less.

[0054] 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 mass% or more, more preferably 45 mass% or more, even more preferably 50 mass% or more, and preferably 75 mass% or less, more preferably 70 mass% or less, even more preferably 65 mass% or less.

[0055] The clay-containing gypsum slurry dispersant of the present invention may optionally contain a thickener, a chelating agent, a heavy metal scavenger, an anti-rust agent, an antiseptic, 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).

[0056] The dispersant for a clay-containing gypsum slurry of the present invention can be suitably used as a dispersant for a gypsum slurry 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 having a clay content of 0.5 mass% or more and 6.0 mass% or less as determined by the methylene blue adsorption test for clay-containing gypsum (JCAS I-61-2008). As the gypsum containing clay, the gypsum described later in relation to the clay-containing gypsum slurry of the present invention can be appropriately used.

[0057] [Method of manufacturing a dispersant for clay-containing gypsum slurry] The present invention relates to a method for producing a dispersant for a clay-containing gypsum slurry, which comprises mixing the component (A). In the method for producing a clay-containing gypsum slurry dispersant of the present invention, the above-mentioned component (B) can be further mixed. In the method for producing a clay-containing gypsum slurry dispersant of the present invention, water can be further mixed. The components (A) and (B) are the same as those described in the clay-containing gypsum slurry dispersant of the present invention. To the method for producing a dispersant for a clay-containing gypsum slurry of the present invention, the embodiments described for the dispersant for a clay-containing gypsum slurry of the present invention can be appropriately applied. In the production method of 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 with the mixed amount in the contents and mass ratios of each component described for the clay-containing gypsum slurry dispersant of the present invention.

[0058] [Clay-containing gypsum slurry] The present invention provides a clay-containing gypsum slurry containing the component (A), gypsum containing clay, and water. It is preferable that the clay-containing gypsum slurry of the present invention further contains a (B) component from the viewpoints of improving water reducing property and increasing the air bubble diameter in the gypsum hardened body. To the clay-containing gypsum slurry of the present invention, the embodiments described in the dispersant for a clay-containing gypsum slurry of the present invention can be appropriately applied. The components (A) and (B) are the same as those described in the clay-containing gypsum slurry dispersant of the present invention. The clay-containing gypsum slurry of the present invention is suitable for use in gypsum boards.

[0059] Gypsum includes anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, and the like. Any type of gypsum can be used, including high-quality neutralized gypsum, phosphogypsum which is a by-product of phosphoric acid, flue gas desulfurization gypsum generated in thermal power generation, natural gypsum containing various impurities and clay, and mixtures of these. The clay-containing gypsum slurry of the present invention is excellent in water reducing property even when gypsum containing clay is used, and therefore natural gypsum can be used. The clay contained in gypsum is mainly composed of hydrated silicate minerals (hereinafter referred to as clay minerals) with a layered structure, and the 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).

[0060] The clay content of gypsum containing clay, as determined by a methylene blue adsorption test (Cement Association Standard Test Method JCAS I-61-2008), is preferably 0.5 mass% or more, more preferably 1.0 mass% or more, and preferably 6.0 mass% or less, more preferably 5.0 mass% or less, from the viewpoint of the range in which component (A) acts efficiently. The methylene blue adsorption test is commonly known as a method for measuring the amount of active clay in sand. The measurement principle is to titrate the amount of methylene blue adsorbed to the sand, and judge the amount by the degree of bleeding (halo) of the spot on the filter paper.

[0061] The clay-containing gypsum slurry of the present invention has a water / gypsum ratio of preferably 40 mass% or more, more preferably 45 mass% or more, and even more preferably 50 mass% or more from the viewpoint of workability, and from the viewpoint of reducing fuel costs, preferably 80 mass% or less, more preferably 75 mass% or less, and even more preferably 70 mass% or less. Here, the water / gypsum ratio is the mass percentage (mass%) of water and gypsum in the clay-containing gypsum slurry, and is calculated by water / gypsum x 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 with respect to gypsum.

[0062] In the clay-containing gypsum slurry of the present invention, the content of the component (A) per 100 parts by mass of gypsum, from the viewpoints of improving water reducing ability and increasing the air bubble diameter in the gypsum hardened body, is preferably 0.04 parts by mass or more, more preferably 0.06 parts by mass or more, even more preferably 0.08 parts by mass or more, and is 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.

[0063] When the clay-containing gypsum slurry of the present invention contains the component (B), the content of the component (B) per 100 parts by mass of gypsum, from the viewpoints of improving water reducing ability and increasing the air bubble diameter in the gypsum hardened body, is preferably 0.04 parts by mass or more, more preferably 0.06 parts by mass or more, even more preferably 0.08 parts by mass or more, still more preferably 0.15 parts by mass or more, still more preferably 0.3 parts by mass or more, and preferably 0.6 parts by mass or less, more preferably 0.55 parts by mass or less, and even more preferably 0.5 parts by mass or less.

[0064] 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 components (A) and (B) is, from the viewpoints of improving water reducing ability and increasing the air bubble diameter in the gypsum hardened body, preferably 0.15 or more, more preferably 0.2 or more, even more preferably 0.25 or more, still more preferably 0.3 or more, and preferably 0.8 or less, more preferably 0.7 or less, even more preferably 0.65 or less, and still more preferably 0.6 or less.

[0065] 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 slurry hardened body.

[0066] Examples of the foaming agent of component (C) include sulfonic acid compounds, ether sulfate compounds, carboxylic acid compounds, phosphonic acid compounds, and phosphoric acid compounds having a hydrocarbon group having from 8 to 18 carbon atoms. For example, one or more compounds selected from alkyl or alkenyl sulfate esters having an alkyl or alkenyl group, alkyl or alkenyl sulfonic acids having an alkyl or alkenyl group, polyoxyalkylene alkyl or alkenyl ether sulfate esters having an alkyl or alkenyl group, polyoxyalkylene alkyl or alkenyl ether carboxylic acids having an alkyl or alkenyl group, and salts thereof can be mentioned. Examples of the 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.

[0067] From the viewpoint of foaming performance, particularly foaming ability, in aqueous systems, component (C) is preferably at least one selected from alkyl or alkenyl sulfate esters having an alkyl or alkenyl group having from 8 to 18 carbon atoms, alkyl or alkenyl sulfonic acids having an alkyl or alkenyl group having from 8 to 18 carbon atoms, polyoxyalkylene alkyl or alkenyl ether sulfate esters having an alkyl or alkenyl group having from 8 to 18 carbon atoms, and salts thereof. Examples of the 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.

[0068] From the viewpoint of foaming performance, particularly foaming ability, in aqueous systems, the (C) component is preferably one or more 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 (C1) component), 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 (C2) component).

[0069] From the viewpoint of increasing the diameter of air bubbles in the gypsum hardened body, the component (C1) preferably has an alkyl or alkenyl group, preferably an alkyl group, having 8 or more carbon atoms, more preferably 10 or more carbon atoms, 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 salts selected from alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0070] 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, it is preferable for the component (C1) to contain one or more compounds selected from decyl sulfate, dodecyl sulfate, tetradecyl sulfate, and salts thereof, and it is more preferable for the component (C1) to contain one or more compounds selected from decyl sulfate, dodecyl sulfate, and salts thereof.

[0071] From the viewpoint of foaming performance, particularly foaming ability, in aqueous systems, the component (C) may contain, as component (C1), two types of alkyl or alkenyl sulfate esters or salts thereof having different numbers of carbon atoms in the alkyl or alkenyl group.

[0072] From the viewpoint of increasing the diameter of air bubbles in the gypsum hardened body, the component (C2) preferably has an alkyl or alkenyl group having 8 or more carbon atoms, more preferably 10 or more carbon atoms, and preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less, and preferably an alkyl group. The oxyalkylene group of component (C2) is an oxyethylene group or an oxypropylene group, and is preferably an oxyethylene group. From the viewpoint of foaming performance, particularly foamability, in an aqueous system, the average number of moles of the oxyalkylene group added is preferably 1 or more, more preferably 2 or more, and from the viewpoint of foaming performance, particularly foamability, in an aqueous system, it is preferably 10 or less, more preferably 6 or less, and even more preferably 4 or less. Examples of the salt of component (C2) include one or more salts selected from alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0073] The (C2) component specifically includes one or more selected from 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, polyoxyethylene polyoxypropylene lauryl ether sulfate, 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 bubble diameter in the gypsum hardened body, it is preferably 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, polyoxyethylene polyoxypropylene myristyl ether sulfate, and salts thereof.

[0074] When the clay-containing gypsum slurry of the present invention contains component (C), the content of component (C) per 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 slurry hardened body.

[0075] The clay-containing gypsum slurry of the present invention can contain additives used for gypsum boards, etc. Such additives include defoamers, foam stabilizers, hardening regulators, water repellents, adhesives, retarders, etc. (excluding those corresponding to components (A), (B), and (C)). Furthermore, glass fiber, carbon fiber, waste paper, virgin pulp, etc. can be added as reinforcing fibers, or gypsum boards can be produced together with lightweight aggregates such as perlite and foamed steel.

[0076] The clay-containing gypsum slurry of the present invention can be 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, from the viewpoint of strength, preferably 0.3 or more, more preferably 0.4 or more, and even more preferably 0.5 or more, and from the viewpoint of handleability, is preferably 0.9 or less, more preferably 0.8 or less, and even more preferably 0.7 or less.

[0077] The clay-containing gypsum slurry of the present invention preferably contains bubbles. From the viewpoint of improving the strength of the hardened body, 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, and even more preferably 300 μm or more, 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, still 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 a clay-containing gypsum slurry, arbitrarily cutting the hardened body to prepare a cross section, observing the cross section with a digital microscope, measuring the diameter of 200 to 400 random bubble cross sections, and averaging these values ​​(arithmetic mean). The diameter of the bubble cross section is measured 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.

[0078] 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 (ratio) of air bubbles is increased to further reduce the weight of the hardened body of the clay-containing gypsum slurry, the ratio 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, the strength of the hardened body of the clay-containing gypsum slurry can be increased by increasing the air bubble diameter in the gypsum slurry. In addition, when the air bubble diameter in the clay-containing gypsum slurry containing air bubbles is increased, the drying time when obtaining the hardened body of the gypsum slurry is quicker, reducing the fuel cost for drying and CO 2 In addition, when the bubble diameter in the clay-containing gypsum slurry is increased, the distance between the bubbles increases, making it difficult for the bubbles to communicate with each other, and improving the heat insulation and sound insulation properties.

[0079] [Method for producing clay-containing gypsum slurry] The clay-containing gypsum slurry of the present invention can be produced using the dispersant for clay-containing gypsum slurry 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. <Process 1> (C) A step of foaming a liquid composition containing a foaming agent (hereinafter referred to as component (C)) and water to obtain a foam. <Process 2> A step of mixing the dispersant for clay-containing gypsum slurry of the present invention, gypsum containing clay, water, and the foam obtained in step 1. Note that in step 2, a clay-containing gypsum slurry containing the dispersant for a clay-containing gypsum slurry of the present invention, gypsum containing clay, and water may be prepared, and the clay-containing gypsum slurry may be mixed with the foam obtained in step 1.

[0080] This manufacturing method makes it possible to prepare the clay-containing gypsum slurry of the present invention that contains air bubbles. The method for producing a clay-containing gypsum slurry of the present invention can appropriately apply the aspects described for the dispersant for a clay-containing gypsum slurry of the present invention and the clay-containing gypsum slurry of the present invention. The component (C) is the same as that described in the clay-containing gypsum slurry of the present invention. The content of the component (C) 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, and the remainder can be water. In the method for producing a clay-containing gypsum slurry of the present invention, the contents of the components and the mass ratios thereof described in the clay-containing gypsum slurry of the present invention can be appropriately applied by replacing the contents of the components with the mixing amounts. The temperatures of the foam and the clay-containing gypsum slurry used in mixing are preferably 15° C. or higher and 40° C. or lower, respectively.

[0081] In step 1, the expansion ratio of the liquid composition varies depending on the application of the gypsum slurry and the like, but from the viewpoint of economic efficiency, it is preferably 5 times or more, more preferably 7 times or more, and even more preferably 10 times or more, and from the viewpoint of kneadability, it is preferably 30 times or less, more preferably 25 times or less, and even more preferably 20 times or less.

[0082] In step 2, depending on the application 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 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 admixtures known in the art can be mixed in step 1 and / or step 2.

[0083] 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 forming and hardening the clay-containing gypsum slurry obtained in step 2. The molding and hardening can be carried out by known methods. For example, the gypsum board can be prepared by referring to "Plaster Board Manufacturing" described on pages 322-324 of "Gypsum Lime Handbook" (edited by the Gypsum Lime Society). EXAMPLES

[0084] The component (A) or component (A′) (a comparative component to component (A)) used in the examples and comparative examples is shown in Table 1.

[0085] [Table 1]

[0086] The constituent monomers in Table 1 used were as follows: MEPEG(120): Methoxypolyethylene glycol (120) monomethacrylate (The number in parentheses is the average number of moles of ethylene oxide added.) ·EX-214L: In general formula (A3), R 8a is a butylene group, m is 1, epoxy equivalent is 134g / mol ·EX-821: In general formula (A3), R 8a Compound with ethylene group and m being 4, epoxy equivalent of 185g / mol ·EX-830: In general formula (A3), R8a Compound with ethylene group and m of 9, epoxy equivalent of 268g / mol ·EX-850: In general formula (A3), R 8a Compound with ethylene group and m of 2, epoxy equivalent of 122g / mol

[0087] In Table 1, the mass % (mol %) of constituent monomer (A1) and the mass % (mol %) of constituent monomer (A2) refer to the proportion of each constituent monomer in the total amount of constituent monomer (A1) and constituent monomer (A2) in all constituent monomers of component (A) or component (A'). In Table 1, the mass % of the crosslinkable monomer (A3) is the proportion (mass %) of the crosslinkable monomer (A3) relative to the total amount (100 mass %) of the constituent monomers (A1) and (A2) in all the constituent monomers of the (A) component or the (A') component. In Table 1, the crosslinking rate (%) of the crosslinkable monomer (A3) is calculated by the following formula (1). Crosslinking rate (%)=[molecular weight of constituent monomer (A1) / proportion (mass%) of (A1) in the constituent monomers of component (A) or component (A')]×[proportion (mass%) of crosslinkable monomer (A3) in component (A) or component (A') / epoxy equivalent of crosslinkable monomer (A3)]×100 (Formula 1) In formula (1), the proportion (mass%) of the constituent monomer (A1) is the proportion of the constituent monomer (A1) in the combined amount of the constituent monomer (A1) and the constituent monomer (A2) in all constituent monomers of component (A) or component (A'), and the proportion (mass%) of the crosslinkable monomer (A3) is the proportion (mass%) of the crosslinkable monomer (A3) relative to the combined amount (100 mass%) of the constituent monomer (A1) and the constituent monomer (A2) in all constituent monomers of component (A) or component (A').

[0088] <Production of Copolymer A-1> 303.64 g of water was placed in a glass reaction vessel equipped with a stirrer, and the inside of the vessel was replaced with nitrogen while stirring, and the temperature was raised to 80° C. in a nitrogen atmosphere. (i) A solution of 653.2 g of an aqueous solution of MEPEG (120) (89.117% by mass of active ingredient, 40.65% by mass of water, containing 2.255% of methacrylic acid as an impurity) and 1.28 g of mercaptoethanol, and (ii) a solution of 2.50 g of ammonium persulfate dissolved in 14.15 g of water, were each dropped into the container over 1.5 hours. Next, a solution of 1.25 g of ammonium persulfate dissolved in 7.07 g of water was dropped over 30 minutes, and then the mixture was aged at the same temperature (80 ° C) for 1 hour. After the aging was completed, the mixture was neutralized with 11.36 g of a 48% aqueous solution of sodium hydroxide to obtain a reaction product containing a methacrylic acid / MEPEG (120) = 62 / 38 (molar ratio) copolymer and water. 200 g of a reaction product (solid content 40% by mass) containing a methacrylic acid / MEPEG (120) = 62 / 38 (molar ratio) copolymer and water was added to 2.5 g of EX-214L (epoxy equivalent 100%) and reacted at 90 ° C. for 5 hours to produce copolymer A-1. Other copolymers in Table 1 were also produced in the same manner as above, except that the types and amounts of the constituent monomers and crosslinkable monomers were changed.

[0089] In Table 1, the weight average molecular weight (Mw) and the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of each copolymer were measured by gel permeation chromatography (GPC) under the following conditions: For A'-2 and A'-4, the molecular weight could not be measured due to gelation. *GPC conditions Equipment: GPC (HLC-8320GPC) manufactured by Tosoh Corporation Column: G4000PWXL+G2500PWXL (Tosoh Corporation) Eluent: 0.2M phosphate buffer / CH 3 CN=9 / 1 Flow rate: 1.0mL / min Column temperature: 40℃ Detection: RI Sample size: 0.2mg / mL Standard substance: Polyethylene glycol equivalent (monodisperse polyethylene glycol with known molecular weight, molecular weight 87,500, 250,000, 145,000, 46,000, 24,000)

[0090] [Evaluation of storage stability of component (A) or component (A')] For each of the synthesized copolymers in Table 1, if gelation proceeds after 5 hours of reaction at 90°C in the above-mentioned manufacturing process, or if gelation proceeds due to residues 3 days after the reaction temperature is lowered after the 5-hour reaction, the storage stability is poor and the copolymer is defined as "X". If gelation does not occur after 5 hours of reaction at 90°C in the above-mentioned manufacturing process, and the reaction temperature is lowered after the 5-hour reaction and the copolymer remains clear and transparent 3 days after the reaction temperature is lowered, the storage stability is good and the copolymer is defined as "O". The results are shown in Table 1. The (A') component with storage stability of "X" gelled and samples could not be taken, so it could not be used in the evaluation of the gypsum slurry described below.

[0091] Table 2 shows the component (B) or component (B′) (a comparative component to component (B)) used in the examples and comparative examples.

[0092] [Table 2]

[0093] The constituent monomers in Table 2 were as follows: MEPEG(120): Methoxypolyethylene glycol (120) monomethacrylate (The number in parentheses is the average number of moles of ethylene oxide added.) · TPEG2700: Isoprenyl ether ethylene oxide adduct (average number of moles of ethylene oxide added: 60 mol) Weight average molecular weight (Mw) 2700 EPEG3000: Vinyl ether ethylene oxide adduct (average number of moles of ethylene oxide added: 65) Weight average molecular weight (Mw): 3000

[0094] <Production of Copolymer B-1> 303.64 g of water was placed in a glass reaction vessel equipped with a stirrer, and the inside of the vessel was replaced with nitrogen while stirring, and the temperature was raised to 80° C. in a nitrogen atmosphere. (i) A solution of 653.2 g of MEPEG (120) (89.117% by mass, 40.65% by mass, containing 2.255% methacrylic acid as an impurity) and 1.28 g of mercaptoethanol, and (ii) a solution of 2.50 g of ammonium persulfate dissolved in 14.15 g of water, were each dropped into the container over 1.5 hours. Next, a solution of 1.25 g of ammonium persulfate dissolved in 7.07 g of water was dropped over 30 minutes, and then the mixture was aged at the same temperature (80 ° C) for 1 hour. After the aging, the mixture was neutralized with 11.36 g of 48% sodium hydroxide aqueous solution to obtain a reaction product containing copolymer B-1 having a weight average molecular weight of 54,882 and water. Other copolymers in Table 2 were also produced in the same manner as above, except that the types and amounts of the constituent monomers were changed.

[0095] In Table 2, the weight average molecular weight (Mw) and the ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of each copolymer were measured by gel permeation chromatography (GPC) under the following conditions. *GPC conditions Equipment: GPC (HLC-8320GPC) manufactured by Tosoh Corporation Column: G4000PWXL+G2500PWXL (Tosoh Corporation) Eluent: 0.2M phosphate buffer / CH 3 CN=9 / 1 Flow rate: 1.0mL / min Column temperature: 40℃ Detection: RI Sample size: 0.2mg / mL Standard substance: Polyethylene glycol equivalent (monodisperse polyethylene glycol with known molecular weight, molecular weight 87,500, 250,000, 145,000, 46,000, 24,000)

[0096] [Analysis of gypsum containing clay] Natural gypsum (1) was used as the gypsum containing clay. The composition of natural gypsum (1) was analyzed by XRF analysis, and the silicon and phosphorus contents were quantified by ICP analysis. The measurement methods are as follows.

[0097] <XRF Analysis> 50 mg of natural gypsum (1) was taken on a filter paper, covered with a PET film, and pressed to obtain a sample. The prepared sample was measured with a fluorescent X-ray analyzer under the following conditions. The results are shown in Table 3. Analyzer: Rigaku wavelength-dispersive fluorescent X-ray PrmusII 2θ (θ: analysis angle): varies depending on the element to be analyzed Target: rhodium tube Tube voltage: 50 kV Tube current: 50 mA Spectrometer crystal: LiF(200), Ge, PET, RX25 Detector: SC, PC

[0098] <ICP Analysis> The reagents used are shown below. Sulfuric acid: for precision analysis, Fuji Film Wako Pure Chemical Industries Hydrochloric acid: for metal analysis, Kanto Chemical Nitric acid: EL grade, Kanto Chemical Hydrogen peroxide: for atomic absorption spectrometry, Fuji Film Wako Pure Chemical Industries Sodium carbonate: special grade, Fuji Film Wako Pure Chemical Industries, Ltd. Boric acid: special grade, Fuji Film Wako Pure Chemical Industries, Ltd. Standard solution for each element: 1000 mg / L for atomic absorption spectrometry, Kanto Chemical Ultra-pure water: Milli-Q water produced by an ultra-pure water manufacturing apparatus, Millipore

[0099] 1. Preparation of samples (i) Pretreatment method for Si 0.1 g of the sample was accurately weighed into a platinum crucible, 2 g of an alkali flux (sodium carbonate: boric acid = 1:0.4) was added, and it was melted in an electric furnace at 950 °C. Covered with a watch glass, 10 mL of ultra-pure water and hydrochloric acid (6 mol / L) were added, and it was heated and dissolved on a hot plate at 70 - 80 °C. After cooling, it was made up to 100 mL with ultra-pure water to obtain a measurement solution. Samples exceeding the calibration curve range were appropriately diluted to obtain measurement solutions. (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 appropriately. The volume was then adjusted to 50 mL with ultrapure water, and the supernatant liquid from which the insoluble matter had precipitated was used as the sample measurement solution. (iii) Preparation of calibration curve solution Using standard solutions for atomic absorption spectrometry (each element: 1000 mg / L), calibration curve solutions of 0.1 to 20 mg / L were prepared. Alkaline flux and hydrochloric acid were added to the solution for Si determination so that the concentrations were the same as those of the sample. Sulfuric acid was added to the solution for P determination so that the concentration was 4%.

[0100] 2. Measurement The samples prepared in step 1 were subjected to measurement of each element using an ICP emission spectrometer under the following conditions. The results are shown in Table 3. Analytical equipment: Thermo Fisher Scientific iCAP6500Duo Wavelength: Si 251.611nm, P 213.618nm RF power: 1150W Coolant gas flow rate: 12L / min Nebulizer flow rate: 0.70L / min Auxiliary gas: 0.5L / min Pump flow rate: 50 rpm

[0101] [Table 3]

[0102] It should be noted that the values ​​from the XRF analysis are not quantitative values ​​but qualitative values ​​indicating peak intensities.

[0103] <Methylene blue adsorption test> The clay content of natural gypsum (1) 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 is to titrate the amount of methylene blue adsorbed to the sand, and is determined by the degree of bleeding (halo) of the spot on the filter paper. The clay content of natural gypsum (1) was 4.93 mass% using the methylene blue adsorption test (JCASI-61-2008).

[0104] [Evaluation of water-reducing properties] A clay-containing gypsum slurry prepared by mixing natural gypsum (1) and water was filled into a paste cone (diameter 50 mm x height 50 mm), which was 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 to measure 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. The average value of these was taken as fluidity, and the amount of water at which the fluidity was 125 mm was defined as a water reduction rate of 0% and used as a reference. The amount of component (A) and / or the amount of component (B) in the clay-containing gypsum slurry was changed to any of the amounts listed in Table 4 in the mass ratio (A) / [(A)+(B)] listed in Table 4, and the amount of water that can be reduced in the same system was defined as the water reduction rate, 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 obtain a fluidity of 125 mm is 200 g (W / G = 80%), if the total amount of components (A) and (B) 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 obtain a fluidity of 125 mm is 160 g (W / G = 64%), then 1-(160 / 200) = 0.2, and the water reduction rate is evaluated as 20%. The results are shown in Table 4.

[0105] [Table 4]

[0106] In Table 4, the mass ratio (A) / ((A)+(B)) and the amount of component (A) and component (B) in the total amount of component (A) and component (B) blended per 100 parts by mass of gypsum are amounts based on the active ingredient. In Table 4, in Comparative Examples 3 and 4, B-1 and B'-1 are not component (A), but are listed in the column for component (A) for convenience of description in the table. In Comparative Example 1-3, the mass ratio (B-1) / (B-2) is 20 / 80, and in Comparative Example 1-4, the mass ratio (B-1) / (B-2) is 20 / 80.

[0107] [Preparation of clay-containing gypsum slurry containing air bubbles] A foaming agent composition containing 100% by mass of sodium decyl sulfate (C10AS) and sodium lauryl sulfate (C12AS) in a mass ratio of C10AS / C12AS = 67 / 33 (mass%), which is the component (C), 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 stirred for 60 seconds at 2000 rpm (EUROSTAR200 control, IKA Japan Co., Ltd.) using a flat 6-blade paddle impeller (FP-50, AS ONE Co., Ltd.) to obtain a foam. 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 such that the blending amounts of component (A) and component (B) per 100 parts by mass of gypsum were as shown in Table 5, and the mixture was stirred for 10 seconds at clockwise 3 (1500 rpm) using a hand mixer (MK-H4, manufactured by Panasonic Corporation) 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 mixture was kneaded in the 1 L disposable cup at 1,500 rpm for 30 seconds using the flat six-blade paddle impeller to obtain a clay-containing gypsum slurry containing air bubbles.

[0108] [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 Co., Ltd.) with a diameter of 5 cm and a height of 10 cm, and left to stand at room temperature for more than 1 hour. The hardened gypsum slurry was demolded from the mold for the cylindrical specimen, left to stand in a thermostatic bath at 60 ° C for 24 hours to dry, and then a cut 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 bubble cross sections were measured at random, and the average bubble diameter was calculated from the arithmetic average of these values. The diameter of the bubble cross section was measured as follows: if the bubble cross section was circular, the diameter was taken; if the bubble cross section was elliptical, the major axis was taken; and if the bubble cross section was irregular, the longest part was taken as the diameter. The results are shown in Table 5. The specific gravity of the obtained gypsum hardened bodies of the examples and comparative examples was all about 0.5.

[0109] [Table 5]

[0110] In Table 5, the amounts of component (A) and component (B) are the effective amounts of each of the components (A) and (B) relative to 100 parts by mass of gypsum in the clay-containing gypsum slurry containing air bubbles. Also, (A) / [(A)+(B)] (mass ratio) is the mass ratio (A) / ((A)+(B)) of the amount of component (A) in the clay-containing gypsum slurry containing air bubbles to the total amount of components (A) and (B).

Claims

1. A dispersant for a clay-containing gypsum slurry, comprising the following component (A): Component (A): a copolymer containing, as constituent monomers, a constituent monomer (A1) represented by the following general formula (A1), a constituent monomer (A2) represented by the following general formula (A2), and a crosslinkable monomer (A3), in which the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) is 1% by mass or more and less than 10% by mass, and the weight average molecular weight is 80,000 or more and 250,000 or less. 【Chemistry 1】 [During the ceremony, 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. M １ａ , M. ２ａ : the same or different, 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 r: a number between 0 and 2 Indicates the following. 【Chemistry 2】 [During the ceremony, R ４ａ , R ５ａ : The same or different, a hydrogen atom or a methyl group R ６ａ : Hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ1 (CO) ｐ１ O (AO) ｎ１ R ７a R ７ａ :Hydrogen atom or 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 5 to 150 q1: a number between 0 and 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 between 0 and 2 Indicates the following.

2. The clay-containing gypsum slurry dispersant according to claim 1 , wherein the crosslinkable monomer (A3) in the component (A) is a monomer represented by the following general formula (A3): 【Chemistry 3】 [During the ceremony, R ８ａ : an alkylene group having 2 to 4 carbon atoms m: an integer of 1 to 30 Indicates the following.

3. The clay-containing gypsum slurry dispersant 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 1% by mass or more and less than 17% by mass. 【Chemistry 4】 [During the ceremony, 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. M １ｂ , M. ２ｂ : the same or different, 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 r: a number between 0 and 2 Indicates the following. 【Chemistry 5】 [During the ceremony, R ４ｂ , R ５ｂ : The same or different, a hydrogen atom or a methyl group R ６ｂ : Hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ｂ , or (CH ２ ) ｑ2 (CO) ｐ2 O (AO) ｎ2 R ７b R ７ｂ :Hydrogen atom or 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 5 to 300 q2: a number between 0 and 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 between 0 and 2 Indicates the following.

4. 4. The clay-containing gypsum slurry dispersant according to claim 3, wherein a mass ratio (A) / ((A)+(B)) of a content of the (A) component to a total content of the (A) component and the (B) component is 0.15 or more and 0.8 or less.

5. The clay-containing gypsum slurry dispersant according to claim 3 or 4, wherein a content of the component (B) is 20% by mass or more and 60% by mass or less.

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

7. 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), a constituent monomer (A2) represented by the following general formula (A2), and a crosslinkable monomer (A3), in which the proportion of the constituent monomer (A1) in the total amount of the constituent monomers (A1) and (A2) is 1% by mass or more and less than 10% by mass, and the weight average molecular weight is 80,000 or more and 250,000 or less. 【Chemistry 6】 [During the ceremony, 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. M １ａ , M. ２ａ : the same or different, 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 r: a number between 0 and 2 Indicates the following. 【Chemistry 7】 [During the ceremony, R ４ａ , R ５ａ : The same or different, a hydrogen atom or a methyl group R ６ａ : Hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ1 (CO) ｐ１ O (AO) ｎ１ R ７a R ７ａ :Hydrogen atom or 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 5 to 150 q1: a number between 0 and 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 between 0 and 2 Indicates the following.

8. The clay-containing gypsum slurry according to claim 7, 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).

9. The clay-containing gypsum slurry according to claim 7 or 8, wherein the crosslinkable monomer (A3) in the component (A) is a monomer represented by the following general formula (A3): 【Chemistry 8】 [During the ceremony, R ８ａ : Ethylene group or propylene group m: an integer of 1 to 30 Indicates the following.

10. The clay-containing gypsum slurry according to any one of claims 7 to 9, 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 1% by mass or more and less than 17% by mass. 【Chemistry 9】 [During the ceremony, 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. M １ｂ , M. ２ｂ : the same or different, 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 r: a number between 0 and 2 Indicates the following. 【Chemistry 10】 [During the ceremony, R ４ｂ , R ５ｂ : The same or different, a hydrogen atom or a methyl group R ６ｂ : Hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ｂ , or (CH ２ ) ｑ2 (CO) ｐ2 O (AO) ｎ2 R ７b R ７ｂ :Hydrogen atom or 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 5 to 300 q2: a number between 0 and 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 between 0 and 2 Indicates the following.

11. The clay-containing gypsum slurry according to claim 10, wherein 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 is 0.15 or more and 0.8 or less.

12. 12. The clay-containing gypsum slurry according to 10 or 11, wherein the component (B) is a copolymer in which n2 in general formula (B2) is 50 or more and 150 or less.

13. The clay-containing gypsum slurry according to any one of claims 7 to 12, further comprising a foaming agent as a component (C).

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