Dispersant for gypsum slurry

Abstract

The present invention provides a dispersant for gypsum slurry that exhibits excellent low-temperature storage stability, even at high solid content concentrations, and suitable for winter conditions (e.g., -5°C to 5°C), and that imparts excellent fluidity to the gypsum slurry, as well as a gypsum slurry with excellent fluidity. [Solution] A dispersant for gypsum slurry containing the following component (A), component (B), and component (C), wherein the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) is 0.05 or more and 0.260 or less. (A) Component: A copolymer containing a specific constituent monomer (A1) represented by general formula (A1) and a specific constituent monomer (A2) represented by general formula (A2) as constituent monomers, wherein the proportion of constituent monomer (A1) in the total amount of constituent monomer (A1) and constituent monomer (A2) is 8% by mass or more and 12% by mass or less. (B) Component: Nitrogen atom-containing alkali compound (C) Component: A specific compound represented by the general formula (C1).

Description

[Technical Field]

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

[0002] Traditionally, naphthalene sulfonic acid formaldehyde condensate has been used as a dispersant in gypsum slurry used for gypsum boards. In recent years, however, the use of polycarboxylic acid-based dispersants has been increasing from the perspective of reducing production costs. When manufacturing gypsum board, the gypsum slurry is formed into a board and then dried in a drying dryer to remove excess water. However, by using a polycarboxylic acid-based dispersant with high water-reducing properties, it becomes possible to form the board with less water, which has the advantage of reducing drying costs. LPG, LNG, coal, and petroleum are used as fuels for drying dryers, but in recent years, with the rise in fuel prices and the increasing importance of CO2 reduction, the advantages of using polycarboxylic acid-based dispersants have become significant.

[0003] Patent Document 1 discloses a one-component liquid dispersant composition for gypsum, which contains (A) a specific polycarboxylic acid copolymer, a specific nitrogen-containing compound such as a specific alkylamine, and water, and is characterized by having a pH of 7.0 or higher and 13.0 or lower at 20°C, and can produce a gypsum slurry with excellent stability and fluidity. Patent Document 2 discloses a cement admixture characterized by containing a comb-like polymer with specific substructure units and optionally an alkanolamine, which can provide a significant improvement effect on cement containing inferior or inexpensive mineral aggregates in terms of milling aid effect, water reduction characteristics, slump (concrete fluidity), fluidity, and strength. Patent Document 3 discloses a dispersant composition for gypsum that can impart superior fluidity to a hydraulic composition containing gypsum, characterized by containing a polymer (A) which includes specific constituent units containing nitrogen, has a weight-average molecular weight of 1,000 to 30,000, and a cation equivalent of 4 meq / g to 16 meq / g in an aqueous solution at pH 7, and a specific polycarboxylic acid copolymer (B). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-24949 [Patent Document 2] International Publication No. 2023 / 036229 [Patent Document 3] Japanese Patent Publication No. 2017-57101 [Overview of the project] [Problems that the invention aims to solve]

[0005] Patent Document 1 discloses a liquid dispersant composition for gypsum containing a specific polycarboxylic acid-based dispersant, a specific nitrogen-containing compound such as a specific alkylamine, and water. However, this liquid dispersant composition for gypsum suffers from phase separation in winter, posing a problem with storage stability, and its solid content cannot be increased, making high-concentration transport difficult and lacking economic rationality. Patent Document 2 discloses that adding an excessive amount of alkanolamine improves the strength of concrete, but this has no strength-improving effect in gypsum applications. Patent Document 3 discloses a means of further improving the fluidity of clay-containing gypsum by using a dispersant composition for gypsum containing a specific polycarboxylic acid-based dispersant and a specific cationic polymer. However, this dispersant composition for gypsum suffers from crystallization in winter, which reduces polymer solubility and generates a gel-like substance, posing a problem with storage stability, and its solid content cannot be increased, making high-concentration transport difficult and lacking economic rationality.

[0006] The present invention provides a dispersant for gypsum slurry, which has excellent low-temperature storage stability assuming winter (e.g., -5°C to 5°C) even when the solid content concentration is high, can impart excellent fluidity to the gypsum slurry, and a gypsum slurry having excellent fluidity.

Means for Solving the Problems

[0007] The present invention relates to a dispersant for gypsum slurry, which contains the following component (A), the following component (B), and the following component (C), and the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) is 0.05 or more and 0.260 or less. (A) component: A copolymer containing a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2) as constituent monomers, and the ratio of the constituent monomer (A1) in the total amount of the constituent monomer (A1) and the constituent monomer (A2) is 8% by mass or more and 12% by mass or less.

[0008]

Chemical Formula

[0009] [In the formula, R 1a , R 2a , R 3a : The same or different, a hydrogen atom, a methyl group or (CH2) r COOM 2a where (CH2) r ed]] COOM 2a is COOM 1a or another (CH2) r COOM 2a When forming an anhydride with them, M 1a , M 2a do 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 This indicates...

[0010] [ka]

[0011] [During the ceremony, R 4a , R 5a : The same or different hydrogen atom or methyl group R 6a : Hydrogen atom, methyl group, (CH2) r COOM 3a , or (CH2) q1 O(AO) n1 R 7a R 7a : Hydrogen atom or alkyl group having 1 to 4 carbon atoms AO: Alkylene oxy group with 2 to 4 carbon atoms n1: The average number of moles added to AO, a number between 40 and 80. q1: A number between 0 and 6 (inclusive) 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 (inclusive) This indicates... (B) Component: Nitrogen atom-containing alkali compound (C) Component: Compound represented by the following general formula (C1)

[0012] [ka]

[0013] [During the ceremony, R 1c , R 2c : The same or different hydrogen atom or methyl group R 3c : Hydrogen atom, methyl group, (CH2) r COOM 1c , or (CH2) q2 O(AO)n2 R 4c R 4c : Hydrogen atom or alkyl group having 1 to 4 carbon atoms AO: Alkylene oxy group with 2 to 4 carbon atoms n2: The average number of moles added to AO, a number between 40 and 80. q2: A number between 0 and 6 (inclusive) M 1c : 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 (inclusive) This indicates...

[0014] The present invention also relates to a gypsum slurry containing component (A), component (B), component (C), gypsum, and water, wherein the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) is 0.05 or more and 0.260 or less. [Effects of the Invention]

[0015] According to the present invention, a dispersant for gypsum slurry and a gypsum slurry with excellent fluidity are provided, which exhibits excellent low-temperature storage stability even when the solid content concentration is high, assuming winter conditions (e.g., -5°C to 5°C).

[0016] The dispersant for gypsum slurry of the present invention exhibits excellent low-temperature storage stability, even at high solid content concentrations, as is typical in winter (e.g., -5°C to 5°C). This allows for higher solid content concentrations, enabling transport at high concentrations and thus offering economic advantages. Furthermore, since the dispersant for gypsum slurry of the present invention can impart excellent fluidity to the gypsum slurry, it becomes possible to form the gypsum slurry with a small amount of water in the gypsum board manufacturing process, thereby reducing the fuel required for drying the gypsum board. This not only achieves both reduced environmental impact and cost reduction simultaneously, but also allows for a reduction in the amount of setting retarder used due to its excellent fluidity. [Modes for carrying out the invention]

[0017] The dispersant for gypsum slurry of the present invention exhibits excellent low-temperature storage stability even at high solid content concentrations, assuming winter conditions (e.g., -5°C to 5°C), and can impart excellent fluidity to the gypsum slurry. The reason why the gypsum slurry of the present invention exhibits excellent fluidity is not entirely clear, but is presumed to be as follows. As disclosed in Patent Document 1, a gypsum slurry with excellent fluidity can be obtained by using a polycarboxylic acid-based dispersant having a specific alkylene oxide chain in combination with a nitrogen atom-containing alkali compound. The polycarboxylic acid-based dispersant (also referred to here as ester-based PCE) having alkylene oxide chains via ester bonds, as used in Patent Document 1, undergoes a synthesis process in which an acid catalyst or neutralizing agent is used in the esterification step, and an acid is added as a copolymerization modifier in the polymerization step. However, when the ester-based PCE obtained through such a synthesis process is mixed with a nitrogen atom-containing alkali compound, the additive components used in each step that remain as impurities combine with the nitrogen atom-containing alkali compound to form a salt. At low temperatures, such as those in winter, crystals precipitate, reducing the solubility of the polymer and resulting in a gel-like substance that does not completely dissolve in water. On the other hand, polycarboxylic acid-based dispersants having alkylene oxide chains via ether bonds (component (A) of the present invention, also referred to here as ether-based PCE), which can be produced without using additive components used in the synthesis process of ester-based PCE, do not cause nitrogen atom-containing alkali compounds to form salts when mixed with them. As a result, the salt concentration at which ether-based PCE becomes insoluble is reduced, and it is presumed that this improves low-temperature stability even at solid content concentrations that were previously difficult to achieve in dispersants for gypsum slurry. Furthermore, component (C) of the present invention, which is an unreacted component contained as an impurity in ether-based PCE, which is component (A) of the present invention, acts as a surfactant and has the characteristic of stabilizing the bubble size of gypsum board. Therefore, in gypsum slurry, component (C) has a preferred range in terms of dispersibility and foam stability. On the other hand, when by-product gypsum such as flue gas desulfurization gypsum or phosphate gypsum is used in gypsum board, it contains acid as an impurity, so it is preferable to include component (B) of the present invention as a pH adjuster. However, if the amount of component (B) does not correspond to the pH of by-product gypsum available on the market, for example, if an excessive amount of component (B) is added, the amount of dispersant component will decrease, and the appropriate effect cannot be obtained. Therefore, it is presumed that there is also a preferred range for this. Therefore, the present inventors have found that by incorporating components (A), (B), and (C) into a dispersant for gypsum slurry or gypsum slurry, and setting the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) within an appropriate range, excellent fluidity can be achieved, leading to the completion of the present invention. However, the present invention is not limited to the above mechanism of action.

[0018] [Dispersant for gypsum slurry] <(A) component> The dispersant for gypsum slurry of the present invention contains a copolymer as component (A), comprising 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 constituent monomer (A1) in the total amount of constituent monomer (A1) and constituent monomer (A2) is 8% by mass or more and 12% by mass or less. In this specification, "a copolymer containing a constituent monomer (A1) represented by general formula (A1) and a constituent monomer (A2) represented by general formula (A2) as constituent monomers" may also mean "a copolymer having constituent units derived from the monomer represented by general formula (A1) and constituent units derived from the monomer represented by general formula (A2)." The same applies to the constituent monomer (A3) described later.

[0019] [ka]

[0020] [During the ceremony, R 1a , R 2a , R 3a : Identical or different, hydrogen atom, methyl group or (CH2) r COOM 2a (CH2) r COOM 2a COOM 1a or other (CH2) r COOM 2a When forming anhydrous compounds, the M of those groups 1a M 2a It does not exist. M 1a M 2a : Same or different hydrogen atoms, alkali metals, alkaline earth metals (1 / 2 atom), ammonium groups, alkylammonium groups, substituted alkylammonium groups, alkyl groups, hydroxyalkyl groups, or alkenyl groups r: A number between 0 and 2 (inclusive) This indicates...

[0021] [ka]

[0022] [During the ceremony, R 4a , R 5a : The same or different hydrogen atom or methyl group R 6a : Hydrogen atom, methyl group, (CH2) r COOM 3a , or (CH2) q1 O(AO) n1 R 7a R 7a : Hydrogen atom or alkyl group having 1 to 4 carbon atoms AO: Alkylene oxy group with 2 to 4 carbon atoms n1: The average number of moles added to AO, a number between 40 and 80. q1: A number between 0 and 6 (inclusive) 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 (inclusive) This indicates...

[0023] In general formula (A1), from the standpoint of availability, R 1a A hydrogen atom is preferred. In general formula (A1), R 2a The atom is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom. In general formula (A1), from the standpoint of availability, R 3a A hydrogen atom is preferred. (CH2) r COOM 2a Regarding COOM 1a or other (CH2) r COOM 2a They may also form anhydrous compounds, in which case the M of those groups 1a M 2a It does not exist. M 1a and M 2a These are identical or different hydrogen atoms, alkali metals, alkaline earth metals (1 / 2 atom), ammonium groups, alkylammonium groups, substituted alkylammonium groups, alkyl groups, hydroxyalkyl groups, or alkenyl groups. M 1a and M 2a The alkyl group, hydroxyalkyl group, and alkenyl group each preferably have 1 to 4 carbon atoms. M 1a and M 2a Preferably, the same or different components are a hydrogen atom, alkali metal, alkaline earth metal (1 / 2 atom), ammonium group, or alkylammonium group; more preferably, a hydrogen atom, alkali metal, alkaline earth metal (1 / 2 atom), or ammonium group; even more preferably, a hydrogen atom, alkali metal, or alkaline earth metal (1 / 2 atom); and still more preferably, a hydrogen atom or alkali metal. (CH2) in general formula (A1) r COOM 2a r is preferably 0.

[0024] In general formula (A2), R 4a From the standpoint of availability, hydrogen atoms are preferred. In general formula (A2), R 5a From the viewpoint of imparting dispersibility to gypsum slurry, availability, and copolymerizability with constituent monomer (A1), a hydrogen atom or a methyl group is preferred, with a methyl group being more preferred. In general formula (A2), R 6a From the standpoint of availability, hydrogen atoms are preferred. In general formula (A2), R 7a From the viewpoint of ease of manufacture and the quality stability of the product, a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred. In general formula (A2), AO is preferably a group selected from an ethyleneoxy group and a propyleneoxy group, with an ethyleneoxy group being more preferred, from the viewpoint of availability and cost. It is preferable that AO contains an ethyleneoxy group. In general formula (A2), n1 is the average number of moles of AO added, and is 40 or more, preferably 45 or more, more preferably 50 or more, and 80 or less, preferably 75 or less, more preferably 70 or less, and even more preferably 60 or less, from the viewpoint of imparting dispersibility to gypsum slurry, low-temperature storage stability, suppression of variations in bubble size in the hardened gypsum slurry containing bubbles, and surface aesthetics of the hardened gypsum. Furthermore, if the AO contains alkylene oxy groups with different numbers of carbon atoms in an average of n1 repeating units, these alkylene oxy groups with different numbers of carbon atoms may include random addition, block addition, or a mixture thereof. In the total AO, ethylene oxy groups are preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, and it is preferable that the total AO is ethylene oxy groups. For example, AO may also contain propylene oxy groups, butylene oxy groups, etc., in addition to ethylene oxy groups. In general formula (A2), from the viewpoint of availability, imparting dispersibility to gypsum slurry, and low-temperature storage stability, q1 is preferably 0, 1, or 2, more preferably 0 or 1, and even more preferably 0. (CH2) in general formula (A2) r COOM 3a M 3a A preferred embodiment is M 1a M 2a This is the same as, and r is preferably 0.

[0025] (A) In all constituent monomers of component (A), the proportion of constituent monomer (A1) in the total amount of constituent monomer (A1) and constituent monomer (A2) is 8% by mass or more, preferably 9% by mass or more, more preferably 10% by mass or more, and 12% by mass or less, preferably 11% by mass or less, from the viewpoint of imparting dispersibility to the gypsum slurry.

[0026] In the total constituent monomers of component (A), the proportion of constituent monomer (A1) in the total amount of constituent monomer (A1) and constituent monomer (A2) is preferably 60 mol% or more, more preferably 65 mol% or more, even more preferably 70 mol% or more, even more preferably 75 mol% or more, and preferably 90 mol% or less, more preferably 85 mol% or less, from the viewpoint of imparting dispersibility to the gypsum slurry.

[0027] In the total constituent monomers of component (A), the proportion of constituent monomer (A2) in the total amount of constituent monomer (A1) and constituent monomer (A2) is preferably 80% by mass or more, more preferably 83% by mass or more, even more preferably 85% by mass or more, and preferably 95% by mass or less, preferably 93% by mass or less, and more preferably 91% by mass or less.

[0028] In the total constituent monomers of component (A), the proportion of constituent monomer (A2) in the total amount of constituent monomer (A1) and constituent monomer (A2) is preferably 10 mol% or more, more preferably 12 mol% or more, even more preferably 15 mol% or more, even more preferably 18 mol% or more, and preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 22 mol% or less.

[0029] (A) Of the total 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 viewpoint of imparting dispersibility to the gypsum slurry. This total amount may be 100% by mass. (A) Of the total 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 viewpoint of imparting dispersibility to the gypsum slurry. This total amount may be 100 mol%.

[0030] The copolymer of component (A) may contain constituent monomers other than constituent monomer (A1) and constituent monomer (A2) (hereinafter also referred to as constituent monomer (A3)). Examples of constituent monomer (A3) include 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. Furthermore, constituent 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)acrylic means acrylic or methacrylic.

[0031] The weight-average molecular weight (Mw) of component (A) is preferably 30,000 or more, more preferably 35,000 or more, even more preferably 37,000 or more, and preferably 80,000 or less, more preferably 70,000 or less, even more preferably 60,000 or less, even more preferably 50,000 or less, and even more preferably 45,000 or less, from the viewpoint of imparting dispersibility to the gypsum slurry.

[0032] (A) The ratio Mw / Mn of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of component (A) is preferably 1.0 or higher, more preferably 1.1 or higher, even more preferably 1.2 or higher, even more preferably 1.4 or higher, and preferably 2.0 or lower, more preferably 1.8 or lower, and even more preferably 1.6 or lower, from the viewpoint of imparting dispersibility to the gypsum slurry.

[0033] 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 Equipment: GPC (HLC-8320GPC), manufactured by Tosoh Corporation. Columns: G4000PWXL + G2500PWXL (manufactured by Tosoh Corporation) Eluent: 0.2M phosphate buffer / CH3CN=9 / 1 Flow rate: 1.0mL / min Column temperature: 40℃ Detection: RI Sample size: 0.2 mg / mL Standard substances: Polyethylene glycol equivalent (monodisperse polyethylene glycols with known molecular weights: 250,000, 145,000, 87,500, 46,000, 24,000)

[0034] The content of component (A) in the solids other than water contained in the dispersant for gypsum slurry of the present invention is preferably 50% by mass or more, more preferably 55% by mass or more, even more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and preferably 85% by mass or less, more preferably 80% by mass or less, from the viewpoint of imparting dispersibility to gypsum slurry, low-temperature storage stability, and economic rationality during transport.

[0035] <(B) component> The dispersant for gypsum slurry of the present invention contains a nitrogen atom-containing alkali compound as component (B). In the present invention, an alkali compound refers to a compound that exhibits alkalinity in a water-soluble solvent system such as water or alcohol. Specifically, component (B) is a compound of component (B) described in Patent Document 1 (Japanese Patent Application Publication No. 2015-24949). More specifically, component (B) is one or more nitrogen-containing compounds selected from ammonia, alkylamines, alkanolamines, ethylenediamines, diethylenetriamines, triethylenetetramine, tetraethylenepentamine, and polyethyleneimine.

[0036] Alkylamines are selected from primary amines with a total of 5 or fewer carbon atoms in the alkyl group, secondary amines with a total of 6 or fewer carbon atoms in the alkyl group, and tertiary amines with a total of 5 or fewer carbon atoms in the alkyl group. The lower limit of the number of carbon atoms in the alkyl group of an alkylamine is 1. Examples of alkylamines include one or more selected from monomethylamine, dimethylamine, monoethylamine, diethylamine, triethylamine, mono-n-propylamine, monoisopropylamine, diisopropylamine, triisopropylamine, mono-n-butylamine, mono-tert-butylamine, mono-sec-butylamine, mono-2-ethylhexylamine, tri-n-octylamine, and N-methylethylamine.

[0037] Alkanolamines include amine compounds having 1 to 10 carbon atoms and 1 to 3 alkanol groups. Examples of alkanolamines include one or more selected from 2-aminoethanol, diethanolamine, and triethanolamine.

[0038] Alkyl alkanolamines include amine compounds having one or more alkyl groups, preferably 1 or more, more preferably 3 or more, preferably 10 or less, more preferably 8 or less, and even more preferably 4 or less, where the alkyl group has one or two alkyl groups. Alkyl alkanolamines specifically include one or more selected from N-monoalkyl-monoalkanolamines, N-monoalkyl-dialkanolamines, and N,N-dialkyl-monoalkanolamines. The number of carbon atoms in the alkyl group is preferably 1 to 4.

[0039] Polyethyleneimines include polymers composed of the constituent unit ethyleneimine-CH2CH2NH-. This polyethyleneimine main chain may branch when a hydrogen atom on a nitrogen atom is substituted by another chain of the constituent unit ethyleneimine. That is, the polyethyleneimine does not have a completely linear structure, but rather a branched chain structure containing primary, secondary, and tertiary amino nitrogens. Tetraethylenepentamine (linear type) is excluded from polyethyleneimines with an average condensation number of 4 constituent units of ethyleneimine, and branched polyethyleneimines are an example of polyethyleneimines with an average condensation number of 4 constituent units of ethyleneimine. The weight-average molecular weight of polyethyleneimine is preferably 200 or more, more preferably 1,000 or more, and preferably 10,000 or less, and more preferably 5,000 or less.

[0040] (B) Component is preferably one or more selected from monoalkanolamines, dialkanolamines, and trialkanolamines, more preferably one or more selected from triethanolamine, diethanolamine, triethanolamine, and triisopropanolamines, and even more preferably one or more selected from triethanolamine and diethanolamines.

[0041] The content of component (B) in the solids other than water contained in the dispersant for gypsum slurry of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 22% by mass or less, from the viewpoint of imparting dispersibility to gypsum slurry, low-temperature storage stability, and economic rationality during transport.

[0042] In the dispersant for gypsum slurry of the present invention, the mass ratio (B) / (A) of the content of component (A) to the content of component (B) is preferably 0.05 or more, more preferably 0.10 or more, still more preferably 0.15 or more, even more preferably 0.20 or more, even more preferably 0.25 or more, and preferably 0.35 or less, more preferably 0.32 or less, still more preferably 0.30 or less, from the viewpoints of imparting dispersibility to the gypsum slurry, low-temperature storage stability, and suppressing the variation in the bubble diameter of the hardened body of the air-containing gypsum slurry.

[0043] The dispersant for gypsum slurry of the present invention contains, as component (C), a compound represented by the following general formula (C1) from the viewpoints of imparting dispersibility to the gypsum slurry and low-temperature storage stability.

[0044]

Chemical formula

[0045] [In the formula, R 1c and R 2c : are the same or different and are a hydrogen atom or a methyl group R 3c : is a hydrogen atom, a methyl group, (CH2) r COOM 1c or (CH2) q2 O(AO) n2 R 4c R 4c : is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms AO: is an alkyleneoxy group having 2 to 4 carbon atoms n2: is the average addition mole number of AO and is a number from 40 to 80 q2: is a number from 0 to 6 M 1c : 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 r: is a number from 0 to 2 is shown. ]

[0046] In the general formula (C1), R 1c is preferably a hydrogen atom from the viewpoint of availability. In the general formula (C1), R 2c is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoints of imparting dispersibility to the gypsum slurry and availability. In the general formula (C1), R 3c is preferably a hydrogen atom from the viewpoint of availability. In the general formula (C1), R 4c is 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 the general formula (C1), 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. It is preferable that AO contains an ethyleneoxy group. In the general formula (C1), n2 is the average number of moles of addition of AO. From the viewpoints of imparting dispersibility to the gypsum slurry, low-temperature storage stability, suppressing variation in the bubble diameter of the gypsum slurry hardened body containing bubbles, and the surface appearance of the gypsum hardened body, it is 40 or more, preferably 45 or more, more preferably 50 or more, and 80 or less, preferably 75 or less, more preferably 70 or less, still more preferably 60 or less. Also, when AO contains alkyleneoxy groups having different carbon numbers in an average of n2 repeating units, these alkyleneoxy groups having different carbon numbers may include random addition, block addition, or a mixture thereof. Among all AO, the ethyleneoxy group is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, and it is preferable that all AO is an ethyleneoxy group. For example, AO can also contain a propyleneoxy group, a butyleneoxy group, etc. in addition to the ethyleneoxy group. In the general formula (C1), from the viewpoints of availability, imparting dispersibility to the gypsum slurry, and low-temperature storage stability, q2 is preferably 0, 1, or 2, more preferably 0 or 1, still more preferably 0. (CH2) in the general formula (C1) r COOM 3c For M of 3c preferred embodiment of M 1a M2a This is the same as, and r is preferably 0.

[0047] If the solid components other than water contained in the dispersant for gypsum slurry of the present invention contain component (C), the content of component (C) is preferably 5% by mass or more, more preferably 7% by mass or more, even more preferably 8% by mass or more, preferably 20% by mass or less, more preferably 17% by mass or less, even more preferably 15% by mass or less, even more preferably 12% by mass or less, even more preferably 10% by mass or less, and even more preferably 9.0% by mass or less.

[0048] In the dispersant for gypsum slurry of the present invention, the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) is 0.05 or more, preferably 0.10 or more, more preferably 0.15 or more, even more preferably 0.20 or more, even more preferably 0.240 or more, and 0.260 or less, preferably 0.255 or less, and more preferably 0.250 or less, from the viewpoint of imparting dispersibility to gypsum slurry, low-temperature storage stability, suppression of variations in the diameter of air bubbles in the hardened gypsum slurry containing air bubbles, and surface aesthetics of the hardened gypsum.

[0049] From the viewpoint of the setting properties of the gypsum slurry, the dispersant for gypsum slurry of the present invention may contain a setting accelerator as component (D). As a setting accelerator, known setting-promoting components can be used. Component (D) includes sulfates such as potassium sulfate, soluble calcium salts such as calcium chloride, calcium nitrite, calcium nitrate, calcium bromide, and calcium iodide, chlorides such as iron chloride and magnesium chloride, potassium hydroxide, sodium hydroxide, carbonates other than calcium carbonate, thiosulfates, formic acid, and formate such as calcium formate, and one or more of these can be used. From the viewpoint of coagulation properties, one or more of component (D) selected from potassium sulfate, calcium nitrite, and calcium chloride are preferred, and one or more selected from calcium sulfate and calcium chloride are more preferred.

[0050] If the dispersant for gypsum slurry of the present invention contains component (D) in solid components other than water, the content of component (D) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and even more preferably 2.0% by mass or less, from the viewpoint of coagulation properties.

[0051] The dispersant for gypsum slurry of the present invention may contain water. When water is contained in the admixture for hydraulic compositions of the present invention, the water content is preferably 30% by mass or more, preferably 40% by mass or more, more preferably 45% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, and even more preferably 60% by mass or less.

[0052] In the dispersant for gypsum slurry of the present invention, the solid content concentration excluding water is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, and even more preferably 60% by mass or less, from the viewpoint of stability and operational aspects.

[0053] The dispersant for gypsum slurry of the present invention may optionally contain thickeners, chelating agents, heavy metal scavengers, rust inhibitors, preservatives, colorants, fragrances, defoamers, solvents, flocculants, water-soluble polymers, etc. (except those corresponding to components (A), (B), (C), and (D)).

[0054] [Method for producing a dispersant for gypsum slurry] The present invention relates to a method for producing a dispersant for gypsum slurry, wherein component (A), component (B), and component (C) are mixed in such a mass ratio (B) / [(A)+(C)] of the amount of component (B) mixed to the total amount of components (A) and (C) mixed is 0.05 or more and 0.260 or less. The method for producing the dispersant for gypsum slurry of the present invention may further involve mixing in component (D). The method for producing a dispersant for gypsum slurry according to the present invention may further involve mixing in water. Components (A), (B), (C), and (D) are the same as those described in the present invention for the dispersant for gypsum slurry. The method for producing the dispersant for gypsum slurry of the present invention can be appropriately applied to the embodiments described in the description of the dispersant for gypsum slurry of the present invention. In the method for producing the dispersant for gypsum slurry of the present invention, the amount of component (A) mixed, the amount of component (B) mixed, the amount of component (C) mixed, the amount of component (D) mixed, the amount of water mixed, the mass ratio of the amount of component (A) to the amount of component (B) mixed (B) / (A), and the mass ratio of the amount of component (B) to the total amount of components (A) and (C) mixed (B) / [(A)+(C)] can be appropriately applied by replacing the content of each component with the amount of mixing in the content and mass ratio of each component described in the dispersant for gypsum slurry of the present invention.

[0055] [Use of dispersants in gypsum slurry] The dispersant for gypsum slurry of the present invention can be suitably used as a dispersant for gypsum slurry containing gypsum. In other words, the present invention relates to the use of a dispersant in a gypsum slurry, wherein the dispersant contains the above-mentioned component (A), component (B), and component (C), and the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) is 0.05 or more and 0.260 or less. The dispersant may further contain component (D). The dispersant may further contain water. Components (A), (B), (C), and (D) are the same as those described in the present invention for the dispersant for gypsum slurry. The aforementioned dispersant is the same as the dispersant for gypsum slurry of the present invention, and the embodiments described in the dispersant for gypsum slurry and its manufacturing method of the present invention can be applied as appropriate.

[0056] [Gypsum slurry] The present invention provides a gypsum slurry containing component (A), component (B), component (C), gypsum, and water, wherein the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) is 0.05 or more and 0.260 or less. The gypsum slurry of the present invention may further contain component (D) above. The gypsum slurry of the present invention can be appropriately adapted to the embodiments described in the dispersant for gypsum slurry and the method for producing the same of the present invention. Components (A), (B), (C), and (D) are the same as those described in the present invention for the dispersant for gypsum slurry. The gypsum slurry of the present invention is suitable for use with gypsum boards.

[0057] Gypsum comes in various forms, including anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. Any type of gypsum can be used, including high-quality neutralized gypsum, phosphate gypsum (a by-product of phosphoric acid production), flue gas desulfurization gypsum (generated from thermal power plants), natural gypsum containing various impurities and clays, and mixtures thereof. One or more of these types of gypsum can be used.

[0058] The gypsum slurry of the present invention has a water / gypsum ratio of preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, from the viewpoint of workability, and preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, and even more preferably 65% ​​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 gypsum content in the gypsum slurry, and is calculated as water / gypsum × 100. The same applies to other quantitative relationships with respect to gypsum in the gypsum slurry of this invention.

[0059] From the viewpoint of imparting dispersibility, the pH of the gypsum slurry of the present invention at 20°C is preferably 8.0 or higher, more preferably 8.5 or higher, and preferably 10.0 or lower, and more preferably 9.5 or lower. pH can be measured using a pH meter. The pH of the gypsum slurry of the present invention at 20°C can be adjusted by including component (B).

[0060] In the gypsum slurry of the present invention, the content of component (A) is preferably 0.05 parts by mass or more, more preferably 0.10 parts by mass or more, even more preferably 0.15 parts by mass or more, and preferably 1.0 part by mass or less, more preferably 0.8 parts by mass or less, even more preferably 0.6 parts by mass or less, even more preferably 0.4 parts by mass or less, even more preferably 0.20 parts by mass or less, and even more preferably 0.18 parts by mass or less, with respect to 100 parts by mass of gypsum.

[0061] In the gypsum slurry of the present invention, the content of component (B) is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, even more preferably 0.02 parts by mass or more, even more preferably 0.04 parts by mass or more, and preferably 0.3 parts by mass or less, more preferably 0.24 parts by mass or less, even more preferably 0.18 parts by mass or less, even more preferably 0.12 parts by mass or less, and even more preferably 0.06 parts by mass or less, with respect to 100 parts by mass of gypsum, from the viewpoint of dispersibility and suppression of variations in the size of air bubbles in the hardened gypsum slurry containing air bubbles.

[0062] In the gypsum slurry of the present invention, the mass ratio (B) / (A) of the content of component (A) to the content of component (B) is preferably 0.05 or more, more preferably 0.10 or more, even more preferably 0.15 or more, even more preferably 0.20 or more, even more preferably 0.25 or more, and preferably 0.35 or less, more preferably 0.32 or less, and even more preferably 0.30 or less, from the viewpoint of dispersibility and suppression of variations in the diameter of air bubbles in the hardened gypsum slurry containing air bubbles.

[0063] In the gypsum slurry of the present invention, the content of component (C) is preferably 0.0005 parts by mass or more, more preferably 0.001 parts by mass or more, even more preferably 0.002 parts by mass or more, even more preferably 0.005 parts by mass or more, even more preferably 0.010 parts by mass or more, even more preferably 0.015 parts by mass or more, and preferably 0.03 parts by mass or less, more preferably 0.024 parts by mass or less, and even more preferably 0.022 parts by mass or less, with respect to 100 parts by mass of gypsum, from the viewpoint of dispersibility and suppression of variations in the diameter of air bubbles in the hardened gypsum slurry containing air bubbles.

[0064] In the gypsum slurry of the present invention, the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) is 0.05 or more, preferably 0.10 or more, more preferably 0.15 or more, even more preferably 0.20 or more, even more preferably 0.240 or more, and 0.260 or less, preferably 0.255 or less, and more preferably 0.250 or less, from the viewpoint of dispersibility, suppression of variations in the diameter of air bubbles in the hardened gypsum slurry containing air bubbles, and surface aesthetics of the hardened gypsum.

[0065] In the gypsum slurry of the present invention, if component (D) is included, the content of component (D) is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and preferably 3.0 parts by mass or less, more preferably 2.5 parts by mass or less, and even more preferably 2.0 parts by mass or less, per 100 parts by mass of gypsum.

[0066] The gypsum slurry of the present invention may contain a foaming agent as component (E) if the gypsum slurry contains air bubbles.

[0067] Examples of foaming agents for component (E) include sulfonic acid compounds, ether sulfate compounds, carboxylic acid compounds, phosphonic acid compounds, and phosphoric acid compounds having hydrocarbon groups with 8 to 18 carbon atoms. For example, one or more selected from 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 one or more selected from alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0068] Component (E) is preferably one or more selected from alkyl or alkenyl sulfate esters having an alkyl or alkenyl group having 8 to 18 carbon atoms, alkyl or alkenyl sulfonic acid having an alkyl or alkenyl group having 8 to 18 carbon atoms, polyoxyalkylene alkyl or alkenyl ether sulfate esters having an alkyl or alkenyl group having 8 to 18 carbon atoms, and salts thereof, particularly in terms of foaming performance in aqueous systems. 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.

[0069] Component (E) is preferably one or more selected from (E1) alkyl or alkenyl sulfate esters or salts thereof having an alkyl or alkenyl group having 8 to 18 carbon atoms (hereinafter referred to as (E1) component), and (E2) polyoxyalkylene alkyl or alkenyl ether sulfate esters or salts thereof having an alkyl or alkenyl group having 8 to 18 carbon atoms (hereinafter referred to as (E2) component).

[0070] Component (E1) preferably has an alkyl or alkenyl group having 8 or more carbon atoms, more preferably 10 or more, preferably 18 or fewer, more preferably 16 or fewer, even more preferably 14 or fewer, and even more preferably 12 or fewer carbon atoms, from the viewpoint of increasing the diameter of air bubbles in the hardened gypsum. The salt of component (E1) may be one or more selected from alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0071] Component (E1) specifically includes one or more 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 hardened gypsum, it is preferable to include one or more compounds selected from decyl sulfate, dodecyl sulfate, tetradecyl sulfate, and salts thereof, and it is more preferable to include one or more compounds selected from decyl sulfate, dodecyl sulfate, and salts thereof.

[0072] Component (E) may contain, as component (E1), two alkyl or alkenyl sulfate esters or salts thereof, having different numbers of carbon atoms in the alkyl or alkenyl group, particularly from the viewpoint of foaming performance in aqueous systems.

[0073] Component (E2) preferably has an alkyl group or alkenyl group having 8 or more carbon atoms, more preferably 10 or more, and more preferably 16 or fewer, more preferably 14 or fewer, and even more preferably 12 or fewer carbon atoms, from the viewpoint of increasing the diameter of air bubbles in the hardened gypsum. The oxyalkylene group of component (E2) is an oxyethylene group or an oxypropylene group, preferably an oxyethylene group, and the average number of moles of oxyalkylene groups added is preferably 1 or more, more preferably 2 or more, and preferably 10 or less, more preferably 6 or less, and even more preferably 4 or less, from the viewpoint of foaming performance in aqueous systems. The salt of component (E2) may be one or more selected from alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0074] (E2) Component specifically includes 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 Examples include polyoxyethylene polyoxypropylene tridecyl ether sulfate, polyoxyethylene polyoxypropylene myristyl ether sulfate, polyoxyethylene polyoxypropylene cetyl ether sulfate, polyoxyethylene polyoxypropylene stearyl ether sulfate, and one or more selected from these salts. From the viewpoint of increasing the diameter of bubbles in the gypsum slurry, it is preferably polyoxyethylene decyl ether sulfate, polyoxyethylene lauryl ether sulfate, polyoxyethylene myristyl ether sulfate, polyoxypropylene decyl ether sulfate, polyoxyethylene polyoxypropylene lauryl ether sulfate, polyoxyethylene polyoxypropylene myristyl ether sulfate, and one or more selected from these salts.

[0075] In the gypsum slurry of the present invention, if component (E) is included, the content of component (E) is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, and preferably 1.0 part by mass or less, more preferably 0.9 parts by mass or less, and even more preferably 0.8 parts by mass or less, with respect to 100 parts by mass of water.

[0076] In the gypsum slurry of the present invention, if component (E) is included, the mass ratio (A) / (E) of the content of component (A) to the content of component (E) is preferably 2.5 or more, more preferably 4.0 or more, even more preferably 4.5 or more, and preferably 12.0 or less, more preferably 9.0 or less, and even more preferably 7.0 or less, from the viewpoint of foaming ability and increasing the diameter of air bubbles in the hardened gypsum.

[0077] The gypsum slurry of the present invention may contain additives used for gypsum boards, etc. Such additives include defoamers, foam stabilizers, hardening modifiers, water repellents, adhesives, retarders, etc. (except for those corresponding to components (A), (B), (C), (D), and (E)). Furthermore, glass fibers, carbon fibers, recycled paper, virgin pulp, etc. may be added as reinforcing fibers, or gypsum boards may be manufactured together with lightweight aggregates such as perlite and foamed steel.

[0078] The gypsum slurry of the present invention yields a hardened gypsum body when dried and cured. From the viewpoint of strength, the specific gravity of the hardened gypsum slurry of the present invention is preferably 0.3 or higher, more preferably 0.4 or higher, and even more preferably 0.5 or higher. From the viewpoint of ease of handling, it is preferably 0.9 or lower, more preferably 0.8 or lower, even more preferably 0.7 or lower, and even more preferably 0.6 or lower.

[0079] The gypsum slurry of the present invention preferably contains air bubbles. When it contains air bubbles, the average air bubble diameter of the hardened gypsum slurry of the present invention is preferably 150 μm or more, more preferably 180 μm or more, even more preferably 190 μm or more, from the viewpoint of improving the strength of the hardened body and improving the surface aesthetics, and 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, even more preferably 400 μm or less, even more preferably 300 μm or less, and even more preferably 250 μm or less, from the viewpoint of cross-sectional aesthetics. The average bubble diameter is calculated by preparing a hardened gypsum slurry, cutting out a cross-section from the hardened material, observing the cross-section with a digital microscope, measuring the diameter of 200 to 400 randomly selected bubble cross-sections, and then calculating the average (arithmetic mean) of these values. Note that when measuring the diameter of a bubble cross-section, if the cross-section is circular, the diameter is measured; if the cross-section is elliptical, the diameter is measured along the major axis; and if the cross-section is irregularly shaped, the diameter is measured along the longest part.

[0080] [Method for producing gypsum slurry] The present invention relates to a method for producing a gypsum slurry, wherein component (A), component (B), component (C), gypsum, and water are mixed in such a mass ratio (B) / [(A)+(C)] of the amount of component (B) mixed to the total amount of components (A) and (C) mixed is 0.05 or more and 0.260 or less. The method for producing gypsum slurry according to the present invention may further involve mixing in component (D). The method for producing gypsum slurry according to the present invention may further involve mixing in component (E). Components (A), (B), (C), and (D) are the same as those described in the present invention for the dispersant for gypsum slurry. The gypsum and component (E) are the same as those described in the gypsum slurry of the present invention. The method for producing gypsum slurry of the present invention can appropriately apply the embodiments described in the present invention concerning the dispersant for gypsum slurry and its production method, as well as the gypsum slurry of the present invention. In the method for producing the hydraulic composition of the present invention, gypsum is mixed so that the water / gypsum ratio falls within the range described for the gypsum slurry of the present invention. In the method for producing gypsum slurry of the present invention, the amount of component (A) mixed, the amount of component (B) mixed, the amount of component (C) mixed, the amount of component (D) mixed, the amount of component (E) mixed, the mass ratio of the amount of component (A) to the amount of component (B) mixed (B) / (A), the mass ratio of the amount of component (B) to the total amount of components (A) and (C) mixed (B) / [(A)+(C)], and the mass ratio of the amount of component (A) to the amount of component (E) mixed (A) / (E) can be appropriately applied by replacing the content of each component with the amount of mixing in the gypsum slurry of the present invention, in the content of each component and their mass ratios.

[0081] In the method for producing gypsum slurry of the present invention, from the viewpoint of productivity, it is preferable to pre-mix component (A), component (B), component (C), an optional component (D), and water, and then mix them with gypsum. Furthermore, in the method for producing gypsum slurry according to the present invention, it is preferable to add component (A), component (B), component (C), and any component (D) using the gypsum slurry dispersant of the present invention, and it is even more preferable to pre-mix the gypsum slurry dispersant of the present invention with water and then mix it with gypsum. In the method for producing gypsum slurry of the present invention, if air bubbles are to be included in the gypsum slurry, foam obtained by foaming a liquid composition containing component (E) and water may be mixed separately into the gypsum slurry.

[0082] The gypsum slurry obtained by the method for producing gypsum slurry of the present invention is molded and hardened. Molding and hardening can be carried out by known methods. For example, gypsum board can be prepared by referring to "Gypsum Board Manufacturing" on pages 322-324 of the "Gypsum Lime Handbook" (edited by the Gypsum Lime Society).

[0083] [Method for producing gypsum slurry containing air bubbles] The gypsum slurry containing air bubbles according to the present invention can be manufactured using the dispersant for gypsum slurry according to the present invention. In other words, the present invention provides a method for producing a gypsum slurry containing air bubbles, comprising the following steps 1 and 2. <Process 1> A step of foaming a liquid composition containing the aforementioned component (E) and water to obtain foam. <Process 2> A step of mixing the dispersant for gypsum slurry of the present invention, gypsum, water, and the foam obtained in step 1. In addition, in step 2, a gypsum slurry containing the gypsum slurry dispersant of the present invention, gypsum, and water may be prepared, and this gypsum slurry may be mixed with the foam obtained in step 1.

[0084] This manufacturing method allows for the preparation of the gypsum slurry containing air bubbles according to the present invention. The method for producing a gypsum slurry containing air bubbles according to the present invention can appropriately apply the embodiments described in the dispersant for gypsum slurry and its production method, as well as the gypsum slurry and its production method according to the present invention. Component (E) is the same as described in the embodiment of the gypsum slurry of the present invention. The content of component (E) in the liquid composition in step 1 is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and preferably 1.0% by mass or less, more preferably 0.9% by mass or less, with the remainder being water. In the method for producing a gypsum slurry containing air bubbles according to the present invention, the gypsum is mixed so that the water / gypsum ratio is within the range described in the gypsum slurry of the present invention. In the method for producing a gypsum slurry containing air bubbles according to the present invention, the amount of component (A) mixed, the amount of component (B) mixed, the amount of component (C) mixed, the amount of component (D) mixed, the mass ratio of the amount of component (A) to the amount of component (B) mixed (B) / (A), the mass ratio of the amount of component (B) to the total amount of components (A) and (C) mixed (B) / [(A)+(C)], and the mass ratio of the amount of component (A) to the amount of component (E) mixed (A) / (E) can be appropriately applied by replacing the content of each component with the amount of mixing in the gypsum slurry described for the present invention. The temperatures of the foam and gypsum slurry used in mixing are preferably between 15°C and 40°C.

[0085] In step 1, the foaming ratio of the liquid composition depends on the intended use of the gypsum slurry, but from an economic standpoint, it is preferably 5 times or more, more preferably 7 times or more, and even more preferably 10 times or more. 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.

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

[0087] After step 2, step 3 is performed to manufacture a hardened gypsum slurry, i.e., gypsum board. Step 3: A step in which the gypsum slurry obtained in Step 2 is molded and hardened. Molding and hardening can be carried out by known methods. For example, gypsum board can be prepared by referring to "Gypsum Board Manufacturing" on pages 322-324 of the "Gypsum Lime Handbook" (edited by the Gypsum Lime Society). [Examples]

[0088] Table 1 shows the components (A) and (A') (comparative components of (A)) used in the examples and comparative examples, and component (B) is shown below.

[0089] [Table 1]

[0090] The constituent monomers used in Table 1 are as follows: APEG2400: Monoallyl ether ethylene oxide adduct (average number of moles of ethylene oxide added: 54 moles) TPEG2400: Isoprenyl ether ethylene oxide adduct (average number of moles of ethylene oxide added: 54 moles) HPEG2400: Methallyl ether ethylene oxide adduct (average number of moles of ethylene oxide added: 54 moles) • MEPEG(120): Methoxypolyethylene glycol (120) monomethacrylate (the number in parentheses represents the average number of moles of ethylene oxide added.)

[0091] <Manufacturing of Copolymer A-1> A 65% concentration, 348.4g aqueous solution of APEG2400 raw material was placed in a 1000ml four-necked flask, and after setting up a stirring blade and condenser, the flask was immersed in an oil bath. The temperature was then raised to 65°C by bubbling with nitrogen gas and nitrogen flow. Subsequently, aqueous solutions of acrylic acid, BMPA (β-mercaptopropionic acid), and L-AS (L-ascorbic acid) were prepared, and each was filled into separate dropping funnels and placed in the four-necked flask. Immediately before starting polymerization, hydrogen peroxide (35%, 0.8g) was added all at once, and while stirring at 250rpm, the acrylic acid solution (40%, 53.2g) and BMPA solution (4.4%, 18.3g) were added dropwise over 3 hours, and the L-AS solution (1.9%, 16.1g) was added over 3.5 hours. After the dropwise addition was complete, the mixture was aged at 65°C for 1 hour, and then neutralized with 48% NaOH (12.3g) to achieve a degree of neutralization of 50%. Other copolymers in Table 1 were also manufactured in the same manner as described above, by changing the type and amount of constituent monomers used.

[0092] In Table 1, the weight-average molecular weight (Mw) and the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn), Mw / Mn, for each copolymer were measured by gel permeation chromatography (GPC) under the following conditions. *GPC conditions Equipment: GPC (HLC-8320GPC), manufactured by Tosoh Corporation. Columns: G4000PWXL + G2500PWXL (manufactured by Tosoh Corporation) Eluent: 0.2M phosphate buffer / CH3CN=9 / 1 Flow rate: 1.0mL / min Column temperature: 40℃ Detection: RI Sample size: 0.2 mg / mL Standard substances: Polyethylene glycol equivalent (monodisperse polyethylene glycols with known molecular weights: 250,000, 145,000, 87,500, 46,000, 24,000)

[0093] <(B) component> • TEA: Triethanolamine, manufactured by Tokyo Chemical Industry Co., Ltd. • DEA: Diethanolamine, manufactured by Tokyo Chemical Industry Co., Ltd.

[0094] [Preparation of dispersant for gypsum slurry] The reaction product containing component (A) or (A') synthesized in the above manufacturing example and water (which includes the constituent monomer (A2) (corresponding to component (C)) as unreacted material), component (B), and water were mixed to prepare each gypsum slurry dispersant in the amounts shown in Tables 2 to 6, respectively. The content of component (C) in each gypsum slurry dispersant was calculated from the peak area measured by the GPC method described above and is shown in Tables 2 to 6. Note that the monomer composition of component (A) or (A') in Table 1 is the composition obtained by subtracting the amount of unreacted component (C) calculated from the peak area measured by the GPC method. In Tables 2-6, the content of component (A) or (A'), component (B), and component (C) represents the content of each component in the solids other than water contained in the gypsum slurry dispersant. The amount of solids other than water in each gypsum slurry dispersant is also shown in Tables 2-6.

[0095] [Low-temperature storage stability test of dispersant for gypsum slurry] Each prepared dispersant for gypsum slurry was placed in a 100 mL screw-cap bottle, sealed, and stored in a constant temperature bath at -5°C for 7 days. After storage, each dispersant for gypsum slurry was visually inspected and evaluated according to the following criteria. The results are shown in Tables 2-4. A: No crystals formed, and no gelation occurred. B: Crystals have formed, or the gel has formed.

[0096] [Evaluation of the fluidity of gypsum slurry] 200g of gypsum (G) (Sakura brand A-grade gypsum, manufactured by Yoshino Gypsum Co., Ltd.) and 114g of mixed water (W) (tap water) containing the prepared dispersants for each gypsum slurry were mixed and stirred for 10 seconds (900rpm) with a hand mixer (MK-H4, manufactured by Panasonic Corporation) to prepare a gypsum slurry. For each dispersant for the gypsum slurry, the mixed water was prepared by adding it to water and stirring so that the content of component (A) or (A'), component (B), and component (C) in the gypsum slurry were as shown in Tables 2 to 4, relative to 100 parts by mass of gypsum. In Tables 2 to 4, W / G (mass%) represents the mass percentage (mass%) of the water content to the gypsum content in the gypsum slurry, and is calculated as water / gypsum × 100. Examples 1-2, 2-2, and 3-2 also show the pH of the gypsum slurry at 20°C. Each gypsum slurry, immediately after preparation, was filled into a paste cone (50 mm in diameter x 50 mm in height), placed on a 30 cm x 30 cm plastic plate, and 30 seconds after the gypsum came into contact with water, the paste cone was lifted vertically. The maximum diameter of the gypsum slurry on the plastic plate and the diameter of the gypsum slurry positioned perpendicular to the maximum diameter on the plastic plate were measured, and the average value of these measurements was defined as fluidity. A higher fluidity value indicates better fluidity. The results are shown in Tables 2-4.

[0097] [Table 2]

[0098] [Table 3]

[0099] [Table 4]

[0100] In Tables 2-4, (B) / (A) (mass ratio) is the mass ratio (B) / (A) of the content of component (B) to the content of component (A) in the gypsum slurry dispersant of the present invention. Also, (B) / [(A)+(C)] (mass ratio) is the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) in the gypsum slurry dispersant of the present invention. Tables 2-4 show that the dispersant for gypsum slurry of the present invention exhibits excellent low-temperature storage stability even at high solid content concentrations. Furthermore, as can be seen in Tables 2-4, the gypsum slurry of the present invention using the dispersant for gypsum slurry of the present invention exhibits excellent fluidity of the gypsum slurry under the condition that component (A) is the same.

[0101] [Preparation of gypsum slurry containing air bubbles] A foaming agent composition containing 100% by mass of component (E), EMALE-27C (manufactured by Kao Corporation), 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 (EUROSTAR200control, manufactured by IKA Japan Co., Ltd.) using a flat 6-blade paddle (FP-50, manufactured by AS ONE Corporation) to obtain foam. 200g of gypsum (Sakura brand A-grade gypsum, manufactured by Yoshino Gypsum Co., Ltd.) and 120g of mixed water (W) (tap water) containing the prepared dispersants for each gypsum slurry were added to a 500mL disposable cup so that the content of components (A), (B), and (C) per 100 parts by mass of gypsum was as shown in Table 5. The mixture was then stirred for 10 seconds at setting 3 (1500rpm) using a hand mixer (MK-H4, manufactured by Panasonic Corporation) to prepare the gypsum slurry before foam addition. The entirety of the prepared 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 1500 rpm for 30 seconds using the flat 6-blade paddle to obtain a gypsum slurry containing air bubbles. In Table 5, W / G (mass%) represents the mass percentage (mass%) of the water content to the gypsum content in the gypsum slurry, and is calculated as water / gypsum × 100. Furthermore, in the gypsum slurry containing air bubbles of the present invention prepared in Table 5, the content of component (E) was 0.036 parts by mass per 100 parts by mass of water, and the mass ratio (A) / (E) of the content of component (A) to the content of component (E) was 5.93.

[0102] [Measurement of average bubble diameter in gypsum] The obtained gypsum slurry containing air bubbles was poured into a mold (Plamold, manufactured by Nifco Corporation) for cylindrical specimens with a diameter of 5 cm and a height of 10 cm, and left to stand at room temperature for more than one hour. The hardened gypsum slurry was demolded from the mold for the cylindrical specimen, and after drying in a 60°C constant temperature bath for 24 hours, a cut was made in the 5 cm section to create a cross-section of the hardened body. The cross-section was observed with a digital microscope, and the diameters of 100 air bubble cross-sections were measured at random. The average air bubble diameter was calculated from the arithmetic mean of these values. When measuring the diameter of the air bubble cross-section, the diameter was measured if the air bubble cross-section was circular, the major axis if the air bubble cross-section was elliptical, and the longest part if the air bubble cross-section was irregular in shape. The results are shown in Table 5. In addition, for each hardened gypsum body, the difference between the maximum and minimum air bubble diameters is shown in Table 5 as the variation in air bubble diameter. It can be said that a smaller variation in air bubble diameter resulted in a hardened gypsum body with better surface aesthetics. The specific gravity of the hardened gypsum bodies obtained in the examples and comparative examples was approximately 0.5 in all cases.

[0103] [Table 5]

[0104] In Table 5, (B) / (A) (mass ratio) is the mass ratio (B) / (A) of the content of component (B) to the content of component (A) in the dispersant for gypsum slurry of the present invention. Also, (B) / [(A)+(C)] (mass ratio) is the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) in the dispersant for gypsum slurry of the present invention. Table 5 shows that the gypsum slurry containing air bubbles using the dispersant for gypsum slurry of the present invention results in a gypsum hardened body with less variation in air bubble diameter after hardening and a good surface appearance.

[0105] [Visual evaluation of hardened gypsum] 200g of gypsum (G) (Sakura brand A-grade gypsum, manufactured by Yoshino Gypsum Co., Ltd.) and 114g of mixed water (W) (tap water) containing the prepared dispersants for each gypsum slurry were mixed and stirred for 10 seconds (900rpm) with a hand mixer (MK-H4, manufactured by Panasonic Corporation) to prepare a gypsum slurry. For each dispersant for the gypsum slurry, the mixed water was prepared by adding it to water and stirring so that the content of component (A) or (A'), component (B), and component (C) in the gypsum slurry were as shown in Table 6 per 100 parts by mass of gypsum (effective amount). In Table 6, W / G (mass%) is the mass percentage (mass%) of the water content to the gypsum content in the gypsum slurry, and is calculated as water / gypsum × 100. The obtained gypsum slurry was poured into a mold (Plamold, manufactured by Floric Co., Ltd.) for cylindrical specimens with a diameter of 5 cm and a height of 10 cm, and left to stand at room temperature for at least one hour. The hardened gypsum slurry was removed from the mold for the cylindrical specimens, and after drying in a 60°C constant temperature bath for 24 hours, the appearance of the resulting hardened gypsum body was visually inspected, and its brightness was determined by whether it appeared white or slightly brown. The results are shown in Table 6.

[0106] [Table 6]

[0107] In Table 6, (B) / (A) (mass ratio) is the mass ratio (B) / (A) of the content of component (B) to the content of component (A) in the dispersant for gypsum slurry of the present invention. Also, (B) / [(A)+(C)] (mass ratio) is the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) in the dispersant for gypsum slurry of the present invention. Table 6 shows that the gypsum slurry produced using the dispersant for gypsum slurry of the present invention results in a hardened gypsum body with a white appearance (color) and good surface aesthetics.

Claims

1. A dispersant for gypsum slurry, comprising the following components (A), (B), and (C), wherein the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) is 0.05 or more and 0.260 or less. (A) Component: A copolymer containing a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2) as constituent monomers, wherein the proportion of constituent monomer (A1) in the total amount of constituent monomer (A1) and constituent monomer (A2) is 8% by mass or more and 12% by mass or less. 【Chemistry 1】 [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 wherein, when (CH ２ ) ｒ COOM ２ａ forms an anhydride with COOM １ａ or another (CH ２ ) ｒ COOM ２ａ the M １ａ and M ２ａ of these groups do not exist. M １ａ M ２ａ : The same or different hydrogen atom, alkali metal, alkaline earth metal (half atom), ammonium group, alkylammonium group, substituted alkylammonium group, alkyl group, hydroxyalkyl group or alkenyl group r: A number between 0 and 2 (inclusive) This indicates... 【Chemistry 2】 [During the ceremony, R ４ａ , R ５ａ : The same or different hydrogen atom or methyl group R ６ａ : Hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ１ O (AO) ｎ１ R ７a R ７ａ : Hydrogen atom or alkyl group having 1 to 4 carbon atoms AO: Alkylene oxy group with 2 to 4 carbon atoms n1: The average number of moles of AO added, a number between 40 and 80. q1: A number between 0 and 6 (inclusive) 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 (inclusive) This indicates... (B) Component: Nitrogen atom-containing alkali compound (C) Component: Compound represented by the following general formula (C1) 【Transformation 3】 [During the ceremony, R １ｃ , R ２ｃ : The same or different hydrogen atom or methyl group R ３ｃ : Hydrogen atom, methyl group, (CH ２ ) ｒ COOM １ｃ , or (CH ２ ) ｑ２ O (AO) ｎ２ R ４ｃ R ４ｃ : Hydrogen atom or alkyl group having 1 to 4 carbon atoms AO: Alkylene oxy group with 2 to 4 carbon atoms n2: The average number of moles of AO added, a number between 40 and 80. q2: A number between 0 and 6 (inclusive) M １ｃ : 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 (inclusive) This indicates...

2. (A) The dispersant for gypsum slurry according to claim 1, wherein the weight-average molecular weight (Mw) of component (A) is 30,000 or more and 80,000 or less, and the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) is 1.0 or more and 2.0 or less.

3. The dispersant for gypsum slurry according to claim 1 or 2, wherein component (B) is one or more nitrogen-containing compounds selected from ammonia, alkylamine, alkanolamine, alkylalkanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and polyethyleneimine.

4. The gypsum slurry dispersant according to claim 1 or 2, wherein component (C) is contained in an amount of 5% by mass or more and 20% by mass or less of the solid content other than water contained in the gypsum slurry dispersant.

5. A gypsum slurry containing the following components (A), (B), and (C), gypsum, and water, wherein the mass ratio (B) / [(A)+(C)] of the content of component (B) to the total content of components (A) and (C) is 0.05 or more and 0.260 or less. (A) Component: A copolymer containing a constituent monomer (A1) represented by the following general formula (A1) and a constituent monomer (A2) represented by the following general formula (A2) as constituent monomers, wherein the proportion of constituent monomer (A1) in the total amount of constituent monomer (A1) and constituent monomer (A2) is 8% by mass or more and 12% by mass or less. 【Chemistry 4】 [During the ceremony, R １ａ , R ２ａ , R ３ａ : The same or different, hydrogen atom, methyl group or (CH ２ ) ｒ COOM ２ａ (CH ２ ) ｒ COOM ２ａ COOM １ａ or other (CH ２ ) ｒ COOM ２ａ When forming an anhydrous, the M of those groups １ａ M ２ａ It does not exist. M １ａ M ２ａ : The same or different hydrogen atom, alkali metal, alkaline earth metal (half atom), ammonium group, alkylammonium group, substituted alkylammonium group, alkyl group, hydroxyalkyl group or alkenyl group r: A number between 0 and 2 (inclusive) This indicates... 【Transformation 5】 [During the ceremony, R ４ａ , R ５ａ : The same or different hydrogen atom or methyl group R ６ａ : Hydrogen atom, methyl group, (CH ２ ) ｒ COOM ３ａ , or (CH ２ ) ｑ１ O (AO) ｎ１ R ７a R ７ａ : Hydrogen atom or alkyl group having 1 to 4 carbon atoms AO: Alkylene oxy group with 2 to 4 carbon atoms n1: The average number of moles of AO added, a number between 40 and 80. q1: A number between 0 and 6 (inclusive) 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 (inclusive) This indicates... (B) Component: Nitrogen atom-containing alkali compound (C) Component: Compound represented by the following general formula (C1) 【Transformation 6】 [During the ceremony, R １ｃ , R ２ｃ : The same or different hydrogen atom or methyl group R ３ｃ : Hydrogen atom, methyl group, (CH ２ ) ｒ COOM １ｃ , or (CH ２ ) ｑ２ O (AO) ｎ２ R ４ｃ R ４ｃ : Hydrogen atom or alkyl group having 1 to 4 carbon atoms AO: Alkylene oxy group with 2 to 4 carbon atoms n2: The average number of moles of AO added, a number between 40 and 80. q2: A number between 0 and 6 (inclusive) M １ｃ : 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 (inclusive) This indicates...

6. The gypsum slurry according to claim 5, wherein the weight-average molecular weight (Mw) of component (A) is 30,000 or more and 80,000 or less, and the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn) is 1.0 or more and 2.0 or less.

7. The gypsum slurry according to claim 5 or 6, wherein component (B) is one or more nitrogen-containing compounds selected from ammonia, alkylamine, alkanolamine, alkylalkanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and polyethyleneimine.

8. The gypsum slurry according to claim 5 or 6, wherein component (C) is contained in an amount of 0.0005 parts by mass or more and 0.03 parts by mass or less per 100 parts by mass of gypsum.

9. The gypsum slurry according to claim 5 or 6, further containing the following component (E). (E) Ingredients: Foaming agent

10. The gypsum slurry according to claim 9, wherein component (E) is one or more selected from (E1) an alkyl or alkenyl sulfate ester or salt thereof having an alkyl or alkenyl group having 8 to 18 carbon atoms, and (E2) a polyoxyalkylene alkyl or alkenyl ether sulfate ester or salt thereof having an alkyl or alkenyl group having 8 to 18 carbon atoms.

11. The gypsum slurry according to claim 9, wherein the mass ratio (A) / (E) of the content of component (A) to the content of component (E) is 2.5 or more and 12 or less.

12. A method for producing a gypsum slurry containing air bubbles, comprising the following steps 1 and 2. <Step 1> A step of foaming a liquid composition containing the following component (E) and water to obtain foam. (E) Ingredients: Foaming agent <Step 2> A step of mixing the dispersant for gypsum slurry according to claim 1 or 2, gypsum, water, and the foam obtained in step 1.

13. A method for producing a gypsum slurry containing bubbles according to claim 12, wherein component (E) is one or more selected from (E1) an alkyl or alkenyl sulfate ester or salt thereof having an alkyl or alkenyl group having 8 to 18 carbon atoms, and (E2) a polyoxyalkylene alkyl or alkenyl ether sulfate ester or salt thereof having an alkyl or alkenyl group having 8 to 18 carbon atoms.

14. A method for producing a gypsum slurry containing bubbles according to claim 12, wherein the mass ratio (A) / (E) of the amount of component (A) mixed to the amount of component (E) mixed is 2.5 or more and 12 or less.

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