Cured gypsum object

Abstract

Provided are: a cured gypsum object containing bubbles which is able to have higher strength due to control of the coefficient of variation in bubble diameter than bubble-containing cured gypsum objects having the same density and the same average bubble diameter; and a method for producing the cured gypsum object.　The cured gypsum object, which contains bubbles, has a density of 0.4 g / cm3 to 0.8 g / cm3, an average bubble diameter of 200-600 μm, and a coefficient of variation in bubble diameter of 0.30-0.48.

Description

hardened gypsum

[0001] The present invention relates to a gypsum hardened body and a method for producing the same.

[0002] BACKGROUND ART Gypsum hardened bodies used in gypsum boards, etc., are lightened by introducing air bubbles into a gypsum slurry containing gypsum and water. Typically, a liquid composition containing a foaming agent composition and water is foamed to obtain foam, which is mixed with a gypsum slurry and then hardened to produce a lightweight cellular gypsum hardened body.

[0003] JP 2004-508259 A describes a foaming agent-surfactant mixture of 0.2 to 1.2 lbs / msf, water of 650 to 1000 lbs / msf, and a foaming agent-surfactant mixture of ≦1330 lbs / msf (6.53 kg / m ２ The document also discloses a gypsum board product made from a gypsum board product slurry containing stucco of 1235 and 1255 lb / msf (approximately 0.380 and 0.386 g / cm), the gypsum board product being 1 / 2 inch thick, having paper on the back and front sides, a total dry weight of ≦1275 lb / msf, and bubbles having a diameter of ≦500 μm within the gypsum board product, and the gypsum board product has sufficient strength and nail pull properties. Also, in the examples, gypsum boards having a thickness of 1 / 2 inch are produced, and the dry weights are about 1235 and 1255 lb / msf (approximately 0.380 and 0.386 g / cm). ３ ) was disclosed.

[0004] Summary of the Invention A gypsum hardened body that uses gypsum as a hardener and contains air bubbles can reduce its density and weight by containing the air bubbles, but on the other hand, the reduced weight reduces its strength. As described in paragraph 0004 of JP-A-10-330174, increasing the air bubble diameter is considered to prevent the strength of the gypsum hardened body from decreasing, but there is a limit to how much the air bubble diameter can be increased. Therefore, a technology is needed that controls the air bubble diameter in the gypsum hardened body to achieve both weight reduction and strength.

[0005] The present invention provides a gypsum hardened body and a method for producing the same, which can increase the strength of a gypsum hardened body by controlling the coefficient of variation of air bubble diameter in gypsum hardened bodies containing air bubbles and having the same density and the same average air bubble diameter.

[0006] The present invention relates to a gypsum hardened body containing bubbles, wherein the density of the gypsum hardened body is 0.4 g / cm ３ 0.8g / cm or more ３ The present invention relates to a gypsum hardened body in which the average bubble diameter in the gypsum hardened body is 200 μm or more and 600 μm or less, and the coefficient of variation of the bubble diameter is 0.30 or more and 0.48 or less.

[0007] The present invention also relates to a method for producing a gypsum hardened body of the present invention, which includes the following steps 1, 2, and 3. <Step 1> A step of foaming a liquid composition containing water and a foaming agent composition including a surfactant (A) (hereinafter referred to as component (A)) to obtain a foam. <Step 2> A step of mixing the foam obtained in step 1 with a gypsum slurry containing gypsum and water to obtain a bubble-containing gypsum slurry. <Step 3> A step after step 2 of molding and hardening the bubble-containing gypsum slurry.

[0008] According to the present invention, a gypsum hardened body and a method for producing the same can be provided, in which the strength of the gypsum hardened body can be increased by controlling the coefficient of variation of the bubble diameter in a gypsum hardened body containing bubbles and having the same density and the same average bubble diameter.

[0009] Modes for Carrying Out the Invention The reason why the gypsum hardened body and its manufacturing method of the present invention can increase the strength of gypsum hardened bodies containing bubbles by controlling the coefficient of variation of bubble diameters even when the gypsum hardened body has the same density and average bubble diameter is not entirely clear, but is presumed to be as follows. Conventionally, as disclosed in, for example, a prior art document (JP 2004-529050 A), relatively large bubbles have been introduced into the gypsum hardened body to improve its mechanical strength. Furthermore, in JP 10-330174 A, relatively large, uniform bubbles have been dispersed in the core to improve adhesion to base paper and the strength of the gypsum hardened body. The present inventors have found that the strength of the gypsum hardened body can be increased by setting the coefficient of variation of bubble diameters in the gypsum hardened body within a specific range. More specifically, the aforementioned problem is solved by setting the coefficient of variation of bubble diameters in the gypsum hardened body to 0.30 or more and 0.48 or less. The larger the coefficient of variation, the greater the variation in bubble diameter, and the smaller the coefficient of variation, the smaller the variation in bubble diameter. If the variation in bubble diameter is too large, the gypsum hardened body will contain coarse bubbles that cause severe stress concentration, resulting in locally weak areas that break and reduce strength. On the other hand, if the bubble diameter in the gypsum hardened body is uniform and the variation is too small, the inter-bubble distance will be narrowed, causing the bubbles in the gypsum hardened body to interconnect and behave as coarse bubbles, resulting in severe stress concentration and reduced strength. In contrast, in a specific range of the coefficient of variation, the absence of coarse bubbles and maintaining a constant inter-bubble distance or greater can suppress bubble interconnection and avoid locally brittle structures. Therefore, it is presumed that improved strength of the gypsum hardened body can be achieved even for gypsum hardened bodies with the same average bubble diameter. Furthermore, by setting the average bubble diameter within the specific range of the present invention, strength can be maintained even when the density of the gypsum hardened body is reduced, thereby achieving both weight reduction and improved strength of the hardened body. However, the present invention is not limited to the above-mentioned mechanism of expression.

[0010] [Gypsum hardened body] The gypsum hardened body in the present invention is obtained by drying and hardening a gypsum slurry containing air bubbles, gypsum, and water. The gypsum hardened body contains air bubbles. From the viewpoint of fire resistance, the density of the gypsum hardened body of the present invention is 0.4 g / cm３ or more, preferably 0.5 g / cm ３ From the viewpoint of ease of handling, 0.8 g / cm ３ or less, preferably 0.75 g / cm ３ The following is the result.

[0011] The average bubble diameter in the gypsum hardened body of the present invention is 200 μm or more, preferably 250 μm or more, more preferably 300 μm or more, even more preferably 400 μm or more, and even more preferably 500 μm or more from the viewpoint of improving the strength of the gypsum hardened body at the same density, and is 600 μm or less, preferably 580 μm or less from the viewpoint of improving the strength and cross-sectional appearance of the gypsum hardened body at the same density. The average bubble diameter in the gypsum hardened body can be adjusted by selecting the type of surfactant in component (A) as the bubble component contained in the gypsum hardened body, or by adding an alcohol in component (B) described below. The average bubble diameter is calculated by preparing a gypsum hardened body containing bubbles, arbitrarily cutting the hardened body to create a cross-section, observing the cross-section with a digital microscope, measuring the diameters of 100 randomly selected bubble cross-sections, and averaging (arithmetic mean) these values. The diameter of the cross section of the cells is measured as follows: if the cross section of the cells is circular, the diameter is measured; if the cross section of the cells is elliptical, the diameter is measured along the major axis; if the cross section of the cells is irregular, the diameter is measured along the longest part.

[0012] In the gypsum hardened body of the present invention, the coefficient of variation of bubble diameter is 0.30 or more, preferably 0.32 or more, more preferably 0.34 or more, from the viewpoint of improving base paper adhesion when made into a gypsum board, and 0.48 or less, preferably 0.45 or less, more preferably 0.43 or less, even more preferably 0.40 or less, even more preferably 0.38 or less, and even more preferably 0.36 or less, from the viewpoint of improving the strength of the gypsum hardened body. The coefficient of variation of bubble diameter in the gypsum hardened body can be adjusted by selecting the type of surfactant in component (A) as the bubble component contained in the gypsum hardened body, adjusting the viscosity of the gypsum slurry using a water reducing agent, or selecting the stirring speed and stirring time when kneading the foam and gypsum slurry. The coefficient of variation of bubble diameter is calculated from the following formula (1) using the standard deviation and average bubble diameter of 100 bubbles measured in the measurement procedure for the average bubble diameter in the gypsum hardened body containing bubbles. Coefficient of variation of bubble diameter = standard deviation of bubble diameter ÷ average bubble diameter Equation (1)

[0013] The gypsum hardened body of the present invention can be obtained by drying a gypsum slurry containing air bubbles, gypsum, and water. A foaming agent composition, which will be described later, can be used to incorporate air bubbles into the gypsum hardened body of the present invention. Examples of the foaming agent composition include a surfactant, a monohydric alcohol having 6 to 10 carbon atoms, and a nonionic compound having a LogP value of 0 to 2.0. The gypsum hardened body of the present invention preferably contains (A) a surfactant (hereinafter referred to as component (A)) and gypsum.

[0014] Examples of the surfactant for the component (A) include one or more surfactants selected from the group consisting of an anionic surfactant (A1) (hereinafter referred to as component (A1)) and a nonionic surfactant (A2) (hereinafter referred to as component (A2)).

[0015] Examples of the anionic surfactant of component (A1) include sulfonic acid compounds, ether sulfate ester compounds, carboxylic acid compounds, phosphonic acid compounds, and phosphoric acid compounds each having a hydrocarbon group having from 8 to 18 carbon atoms. Examples include alkyl or alkenyl sulfate esters having an alkyl or alkenyl group, alkyl or alkenyl sulfonic acids having an alkyl or alkenyl group, olefin sulfonic acids, 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. Examples of salts of these anionic surfactants include alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0016] From the viewpoints of increasing the bubble diameter in the gypsum hardened body and reducing the amount of foaming agent composition added to the gypsum slurry, the component (A11) is preferably an alkyl or alkenyl sulfate ester having an alkyl or alkenyl group having 8 to 18 carbon atoms, or a salt thereof (hereinafter referred to as component (A11)). From the viewpoints of increasing the bubble diameter in the gypsum hardened body and reducing the amount of foaming agent composition added to the gypsum slurry, the component (A11) has an alkyl or alkenyl group, preferably an alkyl group, having 8 or more carbon atoms, preferably 10 or more, and 18 or less, preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less. Examples of the salt of component (A1) include one or more selected from alkali metal salts such as sodium salts and potassium salts, ammonium salts, and organic ammonium salts.

[0017] Specific examples of the component (A11) 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 viewpoints of increasing the bubble diameter in the gypsum hardened body and reducing the amount of foaming agent composition added to the gypsum slurry, the component (A11) preferably contains one or more compounds selected from octyl sulfate, decyl sulfate, dodecyl sulfate, tetradecyl sulfate, and salts thereof, and more preferably contains one or more compounds selected from decyl sulfate, dodecyl sulfate, and salts thereof.

[0018] From the viewpoint of increasing the bubble diameter in the gypsum hardened body and reducing the coefficient of variation of the bubble diameter, the gypsum hardened body of the present invention preferably contains, as component (A11), an alkyl or alkenyl sulfate ester having an alkyl group or alkenyl group having 10 carbon atoms, or a salt thereof. From the viewpoint of increasing the bubble diameter in the gypsum hardened body and reducing the coefficient of variation of the bubble diameter, the content of the alkyl or alkenyl sulfate ester having an alkyl group or alkenyl group having 10 carbon atoms, or a salt thereof in component (A11), is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, more preferably 90% by mass or more, and 100% by mass or less.

[0019] Examples of the nonionic surfactant of component (A2) include alkylene oxide compounds and polyhydric alcohol compounds having a hydrocarbon group having from 8 to 18 carbon atoms, such as one or more compounds selected from alkyl monoglyceryl ethers, polyoxyalkylene monoalkyl or alkenyl ethers, alkyl glycosides or alkyl polyglycosides (alkyl glycoside-type nonionic surfactants), sorbitan-based nonionic surfactants, aliphatic alkanolamides, fatty acid monoglycerides, and sucrose fatty acid esters.

[0020] From the viewpoints of reducing the coefficient of variation of the bubble diameter in the gypsum hardened body and reducing the amount of foaming agent composition added to the gypsum slurry, the component (A21) is preferably an alkylglycoside-type nonionic surfactant (hereinafter referred to as component (A21)). Examples of the component (A21) include alkylglycoside-type surfactants represented by the following general formula (A21): １ａ - (OR ２ａ ) ｐ G ｑ (A21) [In the formula, R １ａ is an alkyl group having 6 to 18 carbon atoms, R ２ａ is an alkylene group having 2 to 4 carbon atoms, G is a residue derived from a reducing sugar, p is a number of 0 to 10 indicating the average number of moles of oxyalkylene groups added, and p R ２ａ may be the same or different, and q is a number of 1 to 3 indicating the average degree of condensation of G.

[0021] In formula (A21), R １ａ The number of carbon atoms in R is preferably 8 or more, more preferably 10 or more, and preferably 14 or less, more preferably 12 or less, from the viewpoints of reducing the coefficient of variation of the bubble diameter in the gypsum hardened body and improving the foaming property of the foaming agent composition contained in the gypsum slurry. ２ａ is preferably an ethylene group or a propylene group, more preferably an ethylene group. p is preferably 5 or less, more preferably 2 or less, and may be 0. q is preferably 2.5 or less, more preferably 2 or less. Examples of G include residues derived from monosaccharides such as glucose, galactose, xylose, mannose, lyxose, arabinose, fructose, or mixtures thereof, and examples of disaccharides or higher include residues derived from maltose, xylobiose, isomaltose, cellobiose, gentiobiose, lactose, sucrose, nigerose, turanose, raffinose, gentianose, menzitose, or mixtures thereof. Among these, preferred raw materials are glucose and fructose for monosaccharides, and maltose and sucrose for disaccharides or higher, from the viewpoint of availability.

[0022] Any type of gypsum can be used, including high-quality neutralized gypsum, phosphogypsum, a by-product of phosphoric acid, flue gas desulfurization gypsum produced in thermal power plants, natural gypsum containing various impurities and clay, and mixtures thereof. The clay contained in gypsum is primarily composed of hydrous silicate minerals (hereinafter referred to as clay minerals) with a layered structure. 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).

[0023] Examples of gypsum include one or more types selected from anhydrous gypsum and gypsum hemihydrate. As the raw gypsum, natural gypsum, chemical gypsum such as neutralized gypsum or by-product gypsum can be used alone, or a mixture of two or more types thereof can be used. Examples of main chemical gypsum include phosphate gypsum, hydrofluoric gypsum, titanic gypsum, and flue gas desulfurization gypsum. Furthermore, the raw gypsum may include recycled gypsum. The recycled gypsum may be any recycled gypsum recovered from waste gypsum board generated in-house by gypsum board manufacturers, waste gypsum board generated during new construction and demolition, etc. The present invention can be suitably used with any of these raw gypsums, and excellent effects can be obtained with blends of these raw gypsums in various ratios.

[0024] The gypsum hardened body of the present invention has a water / gypsum ratio of preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 50% by mass or more, and even more preferably 60% by mass or more from the viewpoint of improving the fluidity of the gypsum slurry, increasing the average bubble diameter of the gypsum hardened body, and reducing the coefficient of variation of the bubble diameter to improve strength. Also, from the viewpoint of improving the strength of the gypsum hardened body, the water / gypsum ratio is preferably 100% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less. Here, the water / gypsum ratio is the mass percentage (mass%) of water and gypsum in the gypsum hardened body and is calculated by multiplying water / gypsum by 100. The water / gypsum ratio may also be the mass percentage of water and gypsum in the gypsum slurry before hardening of the gypsum hardened body.

[0025] The gypsum hardened body of the present invention contains, relative to 100 parts by mass of gypsum, preferably 0.001 parts by mass or more, more preferably 0.004 parts by mass or more, and even more preferably 0.01 parts by mass or more of the component (A) from the viewpoint of reducing the density of the gypsum hardened body, and preferably 0.1 parts by mass or less, more preferably 0.06 parts by mass or less, and even more preferably 0.03 parts by mass or less from the viewpoint of improving the strength of the gypsum hardened body. In the present invention, when the component (A1) is contained in the component (A), the specification regarding the mass of the component (A1) uses a value converted to a sodium salt. The content of the component (A) may be the content in the gypsum slurry before the hardening of the gypsum hardened body.

[0026] When the gypsum hardened body of the present invention contains the component (A1) as the component (A), the component (A1) is contained in an amount of preferably 0.001 part by mass or more, more preferably 0.004 part by mass or more, and even more preferably 0.01 part by mass or more, relative to 100 parts by mass of gypsum, from the viewpoint of reducing the density of the gypsum hardened body, and preferably 0.1 part by mass or less, more preferably 0.06 part by mass or less, and even more preferably 0.03 part by mass or less, from the viewpoint of improving the strength of the gypsum hardened body. The content of the component (A1) may be the content in a gypsum slurry before hardening of the gypsum hardened body.

[0027] When the gypsum hardened body of the present invention contains the component (A11) as the component (A), the component (A11) is preferably contained in an amount of 0.001 part by mass or more, more preferably 0.004 part by mass or more, and even more preferably 0.01 part by mass or more, relative to 100 parts by mass of gypsum, from the viewpoint of reducing the density of the hardened body, and from the viewpoint of increasing the bubble diameter in the gypsum hardened body and improving its strength, the component (A11) is preferably contained in an amount of 0.1 part by mass or less, more preferably 0.06 part by mass or less, and even more preferably 0.03 part by mass or less. The content of the component (A11) may be the content in a gypsum slurry before the hardening of the gypsum hardened body.

[0028] When the gypsum hardened body of the present invention contains the component (A2) as the component (A), the component (A2) is preferably contained in an amount of 0.0001 part by mass or more, more preferably 0.0005 part by mass or more, and even more preferably 0.001 part by mass or more, relative to 100 parts by mass of gypsum, from the viewpoint of reducing the density of the gypsum hardened body, and from the viewpoint of reducing the coefficient of variation of the bubble diameter in the gypsum hardened body and thereby improving its strength, the component (A2) is preferably contained in an amount of 0.01 part by mass or less, more preferably 0.006 part by mass or less, and even more preferably 0.003 part by mass or less, relative to 100 parts by mass of gypsum. The content of the component (A2) may be the content in a gypsum slurry before the hardening of the gypsum hardened body.

[0029] The gypsum hardened body of the present invention can further contain, as component (B), a monohydric alcohol having 6 to 10 carbon atoms, from the viewpoint of improving the foaming rate and foam stability of the foaming agent composition contained in the gypsum slurry and increasing the bubble diameter in the gypsum hardened body. From the viewpoint of improving the foaming rate and foam stability of the foaming agent composition contained in the gypsum slurry, the number of carbon atoms in component (B) is 6 or more and 10 or less, preferably 8. From the viewpoint of improving the foaming rate and foam stability of the foaming agent composition contained in the gypsum slurry, component (B) is a monohydric alcohol having a linear or branched hydrocarbon group, preferably a linear or branched alkyl group, and more preferably a linear alkyl group.

[0030] Specific examples of the (B) component include one or more selected from hexanol, octanol, decanol, 2-ethylhexanol, cyclohexanol, benzyl alcohol, and 2-propylheptanol. From the viewpoint of improving the foaming rate and foam stability of the foaming agent composition contained in the gypsum slurry and increasing the bubble diameter in the gypsum hardened body, the (B) component preferably contains one or more selected from octanol and decanol, more preferably octanol. The content of one or more selected from octanol and decanol in the (B) component is preferably 80% by mass or more, more preferably 90% by mass or more, and preferably 100% by mass or less, and even more preferably substantially 100% by mass. The content of octanol in the (B) component is preferably 80% by mass or more, more preferably 90% by mass or more, and preferably 100% by mass or less, and even more preferably substantially 100% by mass.

[0031] The gypsum hardened body of the present invention contains the component (B) in an amount of preferably 0.00005 parts by mass or more, more preferably 0.0001 parts by mass or more, even more preferably 0.0005 parts by mass or more, and even more preferably 0.001 parts by mass or more, per 100 parts by mass of gypsum, from the viewpoint of improving the foaming speed and foam stability of the foaming agent composition contained in the gypsum slurry, increasing the bubble diameter in the gypsum hardened body, and reducing the density of the gypsum hardened body; and from the viewpoint of reducing odor, preferably 0.01 parts by mass or less, more preferably 0.005 parts by mass or less, and even more preferably 0.003 parts by mass or less. The content of the component (B) may be the content in the gypsum slurry before hardening of the gypsum hardened body.

[0032] The gypsum hardened body of the present invention can further contain, as component (C), a nonionic compound having a Log P of 0 or more and less than 2.0, from the viewpoint of suppressing separation of the foaming agent composition contained in the gypsum slurry. However, component (C) excludes compounds corresponding to component (B). From the viewpoint of liquid phase stability of the foaming agent composition contained in the gypsum slurry, the Log P of component (C) is 0 or more, preferably 0.4 or more, more preferably 0.8 or more, even more preferably 1.0 or more, and less than 2.0, preferably 1.5 or less, more preferably 1.0 or less.

[0033] In the present invention, the log P value is a coefficient indicating the affinity of an organic compound for water and 1-octanol. The 1-octanol / water partition coefficient P is the partition equilibrium when a trace amount of a compound is dissolved as a solute in a two-phase solvent consisting of 1-octanol and water. It is the ratio of the equilibrium concentrations of the compound in each solvent, and is generally expressed in the form of their logarithm (log P) to the base 10. The log P values ​​of many compounds have been reported, and many values ​​can be referenced in databases available from Daylight Chemical Information Systems, Inc. (Daylight CIS). If an actual log P value is not available, it can be calculated using a program such as "ClogP" available from Daylight CIS. This program outputs the "calculated log P (ClogP)" value calculated using the Hansch and Leo fragment approach, along with the actual log P value, if available. The fragment approach is based on the chemical structure of a compound, taking into account the number of atoms and the type of chemical bonds (cf. A. Leo, Comprehensive Medicinal Chemistry, Vol. 4, C. Hansch, P.G. Sammens, J.B. Taylor and C.A. Ramsden, Eds., p. 295, Pergamon Press, 1990). This ClogP value can be used instead of the measured logP value when selecting compounds. In the present invention, if the measured logP value is available, it is used; if not, the ClogP value calculated by the program CLOGP v4.01 is used.

[0034] The nonionic compound of component (C) may be one or more selected from alcohols (excluding component (B)), glycol ethers, and aldehydes, provided that the log P of these nonionic compounds must satisfy the above range.

[0035] The alcohol is preferably a monohydric alcohol, such as 1-propanol (log P: 0.25), 2-propanol (log P: 0.05), 1-butanol (log P: 0.88), 2-butanol (log P: 0.61), 2-methyl-1-propanol (log P: 0.76), 2-methyl-2-propanol (log P: 0.35), 1-pentanol (log P: 1.51), 2- Examples of the alcohol include one or more selected from pentanol (Log P: 1.19), 3-pentanol (Log P: 1.21), 2-methyl-1-butanol (Log P: 1.29), 2-methyl-2-butanol (Log P: 0.89), 3-methyl-2-butanol (Log P: 1.28), 3-methyl-1-butanol (Log P: 1.16), and cyclopentanol (Log P: 0.71).

[0036] The glycol ether is preferably a glycol ether having a hydrocarbon group having 7 or less carbon atoms, and examples thereof include one or more selected from diethylene glycol monobutyl ether (log P: 0.56), ethylene glycol monobutyl ether (log P: 0.81), ethylene glycol monophenyl ether (log P: 1.16), triethylene glycol monobutyl ether (log P: 0.02), and propylene glycol monobutyl ether (log P: 1.15).

[0037] The aldehyde may be at least one selected from butanal (log P: 0.88), pentanal (log P: 1.31), hexanal (log P: 1.78), benzaldehyde (log P: 1.48), and cinnamaldehyde (log P: 1.9).

[0038] Examples of the component (C) other than alcohols, glycol ethers, and aldehydes include one or more selected from butyl lactate (log P: 0.8), dimethyl ether (log P: 0.1), diethyl ether (log P: 0.89), diisopropyl ether (log P: 1.52), tetrahydrofuran (log P: 0.46), propanoic acid (log P: 0.33), butanoic acid (log P: 0.79), pentanoic acid (log P: 1.39), hexanoic acid (log P: 1.92), and benzoic acid (log P: 1.87).

[0039] From the viewpoint of suppressing separation of the foaming agent composition contained in the gypsum slurry, the component (C) is preferably at least one selected from 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-1-butanol, benzaldehyde, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, and diethylene glycol monobutyl ether, and more preferably at least one selected from 1-butanol, 2-methyl-1-butanol, diethylene glycol monobutyl ether, and benzaldehyde.

[0040] The gypsum hardened body of the present invention contains, relative to 100 parts by mass of gypsum, preferably 0.0001 parts by mass or more, more preferably 0.0005 parts by mass or more, and even more preferably 0.001 parts by mass or more of the component (C) from the viewpoint of suppressing separation of the foaming agent composition contained in the gypsum slurry, and from the viewpoint of economic efficiency, preferably 0.01 parts by mass or less, more preferably 0.007 parts by mass or less, and even more preferably 0.005 parts by mass or less. The content of the component (C) may be the content in the gypsum slurry before hardening of the gypsum hardened body.

[0041] The gypsum hardened body of the present invention can contain additives used for gypsum boards, etc. Such additives include water-reducing agents, antifoaming agents, foam stabilizers, hardening accelerators, hardening regulators, water repellents, adhesives, retarders, etc. Furthermore, gypsum boards can be produced by adding reinforcing fibers such as glass fiber, carbon fiber, recycled paper, virgin pulp, etc., or by adding lightweight aggregates such as perlite or foamed steel. Examples of water-reducing agents include one or more selected from naphthalene sulfonic acid polymers, polycarboxylic acid polymers, melamine sulfonic acid polymers, and phosphate ester polymers, etc., preferably one or more selected from naphthalene sulfonic acid polymers and polycarboxylic acid polymers. Examples of hardening accelerators include one or more selected from gypsum dihydrate and potassium sulfate.

[0042] The gypsum hardened body of the present invention can be suitably used for gypsum boards, fireproof materials, etc.

[0043] [Method for Producing Gypsum Hardened Body] The present invention provides a method for producing a gypsum hardened body of the present invention, which includes the following steps 1, 2, and 3. <Step 1> A step of foaming a liquid composition containing water and a foaming agent composition (hereinafter referred to as the foaming agent composition of the present invention) containing a surfactant (A) (hereinafter referred to as component (A)) to obtain a foam. <Step 2> A step of mixing the foam obtained in step 1 with a gypsum slurry containing gypsum and water to obtain a bubble-containing gypsum slurry. <Step 3> A step after step 2 of molding and hardening the bubble-containing gypsum slurry.

[0044] The gypsum hardened body of the present invention can be produced by this production method. The methods for producing the gypsum hardened body of the present invention can be appropriately applied to the methods for producing the gypsum hardened body of the present invention.

[0045] <Step 1> Step 1 is a step of foaming a liquid composition containing the foaming agent composition according to the present invention and water to obtain a foam. The foaming agent composition according to the present invention contains a surfactant as component (A). Component (A) is the same as component (A) described for the gypsum hardened body of the present invention, and preferred embodiments are also the same.

[0046] The foaming agent composition according to the present invention contains the component (A) in an amount of preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, still more preferably 20% by mass or more, and still more preferably 25% by mass or more, from the viewpoints of reducing the density of the gypsum hardened body and reducing the amount of foaming agent composition added, and in an amount of preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and still more preferably 35% by mass or less, from the viewpoints of improving the strength of the gypsum hardened body and suppressing separation of the foaming agent composition.

[0047] When the foaming agent composition according to the present invention contains the component (A1) as the component (A), the component (A1) is preferably contained in an amount of 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, still more preferably 20% by mass or more, and still more preferably 25% by mass or more, from the viewpoints of reducing the density of the gypsum hardened body and reducing the amount of foaming agent composition added; and from the viewpoints of improving the strength of the gypsum hardened body and suppressing separation of the foaming agent composition, the component (A1) is preferably contained in an amount of 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and still more preferably 35% by mass or less.

[0048] When the foaming agent composition according to the present invention contains the component (A11) as the component (A), the component (A11) is preferably contained in an amount of 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, still more preferably 20% by mass or more, and still more preferably 25% by mass or more, from the viewpoints of reducing the density of the hardened body and reducing the amount of foaming agent composition added; and the component (A11) is preferably contained in an amount of 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and still more preferably 35% by mass or less, from the viewpoints of increasing the bubble diameter in the gypsum hardened body to improve strength and suppressing separation of the foaming agent composition.

[0049] When the foaming agent composition according to the present invention contains the component (A2) as the component (A), the component (A2) is preferably contained in an amount of 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, from the viewpoints of reducing the density of the gypsum hardened body and reducing the amount of foaming agent composition added; and the foaming agent composition is preferably contained in an amount of 10% by mass or less, more preferably 7% by mass or less, even more preferably 4% by mass or less, still more preferably 3% by mass or less, and still more preferably 2.5% by mass or less, from the viewpoints of reducing the coefficient of variation of the bubble diameter in the gypsum hardened body to improve strength and suppressing separation of the foaming agent composition.

[0050] From the viewpoint of reducing the amount of foaming agent composition added, the foaming agent composition according to the present invention can further contain, as component (B), a monohydric alcohol having from 6 to 10 carbon atoms. Component (B) is the same as component (B) described for the gypsum hardened body of the present invention, and preferred embodiments are also the same.

[0051] When the foaming agent composition according to the present invention contains the component (B), the component (B) is preferably contained in an amount of 1% by mass or more, more preferably 2% by mass or more, and even more preferably 2.5% by mass or more from the viewpoints of increasing the bubble diameter in the gypsum hardened body, reducing the density of the gypsum hardened body, and improving the foaming speed and foam stability of the foaming agent composition; and the foaming agent composition is preferably contained in an amount of 30% by mass or less, more preferably 20% by mass or less, even more preferably 10% by mass or less, still more preferably 5% by mass or less, and still more preferably 4% by mass or less from the viewpoint of suppressing separation of the added amount of the foaming agent composition.

[0052] From the viewpoint of suppressing separation of the foaming agent composition, the foaming agent composition according to the present invention can further contain, as component (C), a nonionic compound (excluding compounds corresponding to component (B)) having a Log P of 0 or more and less than 2.0. Component (C) is the same as component (C) described in the gypsum hardened body of the present invention, and preferred embodiments are also the same.

[0053] When the foaming agent composition according to the present invention contains component (C), the component (C) is preferably contained in an amount of 2% by mass or more, more preferably 3% by mass or more, and even more preferably 4% by mass or more, from the viewpoint of suppressing separation of the foaming agent composition; and from the viewpoint of reducing the amount of foaming agent composition added, the component (C) is preferably contained in an amount of 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, still more preferably 6% by mass or less, and even more preferably 5% by mass or less.

[0054] The foaming agent composition according to the present invention contains water. The foaming agent composition according to the present invention contains water in an amount of preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, still more preferably 40% by mass or more, still more preferably 50% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, and still more preferably 70% by mass or less.

[0055] The foaming agent composition according to the present invention may contain other components such as thickeners, chelating agents, heavy metal scavengers, rust inhibitors, preservatives, colorants, fragrances, defoamers, flocculants, water-soluble polymers, etc. These do not fall under the category of component (A), component (B), or component (C).

[0056] In Step 1, a liquid composition containing the foaming agent composition according to the present invention and water is foamed to obtain a foam. The foaming ratio of the liquid composition is preferably 3 times or more, more preferably 5 times or more, and even more preferably 7 times or more from the viewpoint of economic efficiency, and is preferably 20 times or less, more preferably 15 times or less, and even more preferably 10 times or less from the viewpoint of kneadability of the gypsum slurry and the foam.

[0057] <Step 2> In step 2, the foam obtained in step 1 is mixed with a gypsum slurry containing gypsum and water to obtain a bubble-containing gypsum slurry. The gypsum slurry preferably contains a water-reducing agent from the viewpoint of adjusting the viscosity of the gypsum slurry and controlling the coefficient of variation of the bubble diameter in the gypsum hardened body. Examples of the water-reducing agent include one or more selected from naphthalene sulfonic acid polymers, polycarboxylic acid polymers, melamine sulfonic acid polymers, and phosphate ester polymers, and preferably one or more selected from naphthalene sulfonic acid polymers and polycarboxylic acid polymers. The gypsum slurry may also contain a hardening accelerator. Examples of the hardening accelerator include one or more selected from gypsum dihydrate and potassium sulfate. In step 2, the foam is mixed with the gypsum slurry in an amount of preferably 50% by volume or more, more preferably 75% by volume or more, and even more preferably 100% by volume or more from the viewpoint of reducing the weight of the hardened body, and in an amount of preferably 200% by volume or less, more preferably 150% by volume or less, and even more preferably 100% by volume or less from the viewpoint of improving the strength of the hardened body. In this production method, an admixture known in the art can be mixed in step 1 and / or step 2.

[0058] In step 2, the mixed amounts of the (A), (A1), (A2), (B), and (C) components in the bubble-containing gypsum slurry can be appropriately applied by replacing the contents of each component described for the gypsum hardened body of the present invention with the mixed amounts. The water / gypsum ratio in the bubble-containing gypsum slurry is the same as the water / gypsum ratio range described for the gypsum hardened body of the present invention. The temperatures of the foam and gypsum slurry used for mixing are preferably 15° C. or higher and 40° C. or lower, respectively.

[0059] In step 2, the kneading speed of the foam and the gypsum slurry is preferably 250 rpm or more, more preferably 500 rpm or more, even more preferably 750 rpm or more, and still more preferably 1000 rpm or more from the viewpoint of increasing the bubble diameter in the gypsum hardened body, reducing the coefficient of variation, and improving kneadability, and is preferably 2000 rpm or less, more preferably 1800 rpm or less from the viewpoint of suppressing degassing. In step 2, the kneading time of the foam and the gypsum slurry is preferably 1 second or more, more preferably 3 seconds or more, and even more preferably 5 seconds or more from the viewpoint of increasing the bubble diameter in the gypsum hardened body, reducing the coefficient of variation, and improving kneadability, and is preferably 60 seconds or less, more preferably 30 seconds or less, and even more preferably 20 seconds or less from the viewpoint of suppressing degassing. Methods for kneading the foam and gypsum slurry are well known and can be performed using, for example, the methods described in U.S. Patent Nos. 4,518,652, 2,080,009, and 2,017,022. When performed on a laboratory scale, a method can be used in which the gypsum slurry is charged into the foam in a 1-L disposable cup, and the mixture is kneaded in the 1-L disposable cup using a mixer equipped with six flat paddle blades (e.g., FP-50, manufactured by AS ONE Corporation) at a kneading speed of 500 rpm to 2000 rpm for 1 second to 30 seconds.

[0060] <Step 3> After step 2, the following step 3 is further carried out to produce a gypsum hardened body. Step 3: After step 2, the bubble-containing gypsum slurry is molded and hardened. The molding and hardening can be carried out by known methods. For example, gypsum boards, fireproof materials, etc. can be produced by referring to "Gypsum Board Production" described on pages 322 to 324 of "Gypsum Lime Handbook" (edited by the Gypsum Lime Society).

[0061] Examples The components used in the foaming agent compositions in Table 1 are as follows: Component (A) C10AS: sodium decyl sulfate, Component (A11) C13AS: sodium alkyl sulfate having an alkyl group with 12 to 16 carbon atoms (mass ratio: carbon numbers 12 / 14 / 16 = 63.5 / 23.5 / 13.0), Component (A11) AES: sodium polyoxyethylene alkyl ether sulfate, product name "EMAL D-3-D", manufactured by Kao Corporation, Component (A1) AG: lauryl glycoside, product name "MYDOL 12", manufactured by Kao Corporation, Component (A21) Component (B) C8OH: octanol, product name "Kalcol 0898", manufactured by Kao Corporation Component (C) BDG: diethylene glycol monobutyl ether, log P: 0.56, manufactured by Tokyo Chemical Industry Co., Ltd.

[0062] Examples 1 to 3 and Comparative Examples 1 and 2 (1) Preparation of Foaming Agent Compositions The foaming agent compositions shown in Table 1 were prepared by the following method. The ingredients listed in Table 1 were added to a 50 mL screw tube in the prescribed proportions so that a total of 30 g was obtained, and the mixture was stirred at 1000 rpm for 3 hours using a stirrer to prepare the foaming agent compositions. When the solution viscosity was high and stirring efficiency was poor, the mixture was heated to 40°C as appropriate.

[0063]

[0064] (2) Preparation of gypsum slurry The foaming agent composition and water described in Table 1 were mixed in proportions to the concentrations described in Tables 2 and 3 to prepare a diluted aqueous solution of the foaming agent composition. 25 g of the prepared diluted aqueous solution was added to a 1 L disposable cup, and a mixer (EUROSTAR 200 control, manufactured by IKA Japan Co., Ltd.) equipped with a flat six-paddle blade (FP-50, manufactured by AS ONE Corporation) was used. The mixture was stirred for 60 seconds at 2000 rpm to obtain a foam. 200 g of calcined gypsum, 2 g of dihydrate gypsum, 150 g of water, and 0.8 g of a water-reducing agent (Mighty 150, manufactured by Kao Corporation) were added to a 500 mL disposable cup, and the mixture was stirred for 20 seconds at memory 3 using a hand mixer (MK-H4, manufactured by Panasonic Corporation) to prepare a gypsum slurry before adding the foam. The entire amount of the prepared gypsum slurry was added to 25 g of foam prepared in a 1 L disposable cup, and the mixture was kneaded for 30 seconds in the 1 L disposable cup using the mixer equipped with the flat six-paddle blade at the kneading speed shown in Tables 2 and 3 to obtain a gypsum slurry containing bubbles. The water / gypsum ratio in the gypsum slurry was 75 mass%. The temperatures of the foam and the gypsum slurry used for kneading were both 20°C.

[0065] (3) Measurement of the average bubble diameter and coefficient of variation of bubble diameter in the gypsum hardened body The obtained gypsum slurry containing bubbles was poured into a mold for a cylindrical specimen having a diameter of 5 cm and a height of 10 cm (Plamold, manufactured by Nifco Co., Ltd.) and left to stand at room temperature for at least 1 hour. The hardened gypsum slurry was demolded from the mold for the cylindrical specimen and left to dry in a thermostatic bath at 60 ° C for 24 hours, and then a slit was made in the 5 cm high section to create a cross section of the hardened body. The cross section was observed with a digital microscope, and the diameters of 100 arbitrary bubble cross sections were measured, and the average bubble diameter was calculated from the arithmetic average of these values. Note that the diameter of the bubble cross section is measured as the diameter if the bubble cross section is circular, the major axis if the bubble cross section is elliptical, and the longest part if the bubble cross section is irregular. The results of the average bubble diameter in the gypsum hardened body are shown in Tables 2 and 3. The coefficient of variation of the bubble diameter in the obtained gypsum hardened body was calculated from the standard deviation and average bubble diameter of the 100 bubble diameters measured by the above procedure using the following formula (1). The results of the coefficient of variation of the bubble diameter in the gypsum hardened body are shown in Tables 2 and 3. Coefficient of variation of bubble diameter = standard deviation of bubble diameter / average bubble diameter Formula (1) The densities of the obtained hardened stone bodies are also shown in Tables 2 and 3.

[0066] (4) Measurement of strength of gypsum hardened body The gypsum hardened bodies in Tables 2 and 3 obtained in (3) were allowed to stand in a thermostatic chamber at 40°C for 2 hours, and then immediately measured for compressive strength at a compression rate of 1 mm per minute using a strength tester (CONCRETO2000X, Shimadzu Corporation). The results are shown in Tables 2 and 3.

[0067]

[0068]

[0069] The gypsum hardened bodies in Tables 2 and 3 each had a test specimen density of 0.51 g / cm ３ and 0.73 g / cm ３ It can be seen that even if the specimen density and average bubble diameter of the gypsum hardened body are approximately the same, the compressive hardness is improved by setting the value of the coefficient of variation of the bubble diameter of the gypsum hardened body within the range of the present invention.

[0070] Examples 4 to 10 and Comparative Example 3 The foaming agent composition shown in Table 1 and water were mixed in proportions to achieve the concentrations shown in Table 4 to prepare diluted aqueous solutions of the foaming agent composition. Then, gypsum slurries were prepared in the same manner as in (2) Preparation of Gypsum Slurries, except that the preparation conditions for the gypsum slurry were changed to those shown in Table 4. Note that, in terms of the type of water-reducing agent, NSF indicates naphthalenesulfonic acid formaldehyde condensate salt (Mighty 150, manufactured by Kao Corporation), and PCE indicates a polycarboxylic acid ether-based high-performance water-reducing agent (Mighty 21ER, manufactured by Kao Corporation). Potassium sulfate is a hardening accelerator (which does not contribute to improving compressive strength) and was added at the same time as the gypsum dihydrate.

[0071]

[0072] The gypsum hardened bodies in Table 4 tend to have a lower compressive strength as the density of the gypsum hardened body specimen decreases, so the test results are arranged in order of specimen density from lowest to highest so that the compressive strength can be compared between hardened bodies with similar densities. When comparing gypsum hardened bodies with similar specimen densities, it can be seen that compressive strength is improved by setting the average air bubble diameter and coefficient of variation of air bubble diameter of the gypsum hardened body within the ranges of the present invention.

Claims

1. A gypsum hardened body containing air bubbles, wherein the density of the gypsum hardened body is 0.4 g / cm ３ 0.8g / cm or more ３ below, The average bubble diameter in the gypsum hardened body is 200 μm or more and 600 μm or less, A gypsum hardened body having a coefficient of variation of air bubble diameter of 0.30 or more and 0.48 or less.

2. The density of the gypsum hardened body is 0.5 g / cm ３ 0.75g / cm or more ３ The gypsum hardened body according to claim 1, wherein:

3. The gypsum hardened body according to claim 1 or 2, wherein an average bubble diameter in the gypsum hardened body is 250 μm or more and 580 μm or less.

4. The gypsum hardened body according to claim 1 or 2, wherein a coefficient of variation of air bubble diameter in the gypsum hardened body is 0.32 or more and 0.43 or less.

5. The gypsum hardened body according to claim 1 or 2, comprising (A) a surfactant (hereinafter referred to as component (A)) and gypsum.

6. The gypsum hardened body according to claim 5, wherein the component (A) is at least one selected from the group consisting of an anionic surfactant (A1) (hereinafter referred to as component (A1)) and a nonionic surfactant (A2) (hereinafter referred to as component (A2)).

7. The gypsum hardened body according to claim 6, wherein the component (A1) is an alkyl or alkenyl sulfate ester having an alkyl or alkenyl group having 8 to 18 carbon atoms, or a salt thereof.

8. The gypsum hardened body according to claim 6, wherein the component (A2) is an alkyl glycoside type nonionic surfactant.

9. The gypsum hardened body according to claim 5 , further comprising (B) a monohydric alcohol having 6 to 10 carbon atoms (hereinafter referred to as component (B)).

10. The gypsum hardened body according to claim 5, further containing (C) a nonionic compound having a Log P of 0 or more and less than 2.0 (excluding compounds corresponding to component (B)).

11. The gypsum hardened body according to claim 1 or 2, which is a gypsum board.

12. The method for producing a gypsum hardened body according to claim 1, comprising the following steps 1, 2, and 3. <Step 1> (A) A step of foaming a liquid composition containing a foaming agent composition including a surfactant (hereinafter referred to as component (A)) and water to obtain a foam. <Step 2> A step of mixing the foam obtained in step 1 with a gypsum slurry containing gypsum and water to obtain a bubble-containing gypsum slurry. <Step 3> After step 2, the air bubble-containing gypsum slurry is molded and hardened.

13. The method for producing a gypsum hardened body according to claim 12, wherein in step 2, a kneading speed for mixing the foam and the gypsum slurry is 250 rpm or more and 2000 rpm or less.

14. The method for producing a gypsum hardened body according to claim 12 or 13, wherein in step 2, a kneading time for mixing the foam and the gypsum slurry is 1 second or more and 60 seconds or less.

15. The method for producing a gypsum hardened body according to claim 12 or 13, wherein the component (A) is at least one selected from an anionic surfactant (A1) (hereinafter referred to as component (A1)) and a nonionic surfactant (A2) (hereinafter referred to as component (A2)).

16. The method for producing a gypsum hardened body according to claim 15, wherein the component (A1) is an alkyl or alkenyl sulfate ester having an alkyl or alkenyl group having 8 to 18 carbon atoms, or a salt thereof.

17. The method for producing a gypsum hardened body according to claim 15, wherein the component (A2) is an alkyl glycoside type nonionic surfactant.

18. The method for producing a gypsum hardened body according to claim 12 or 13, wherein the foaming agent composition further contains (B) a monohydric alcohol having 6 to 10 carbon atoms (hereinafter referred to as component (B)).

19. The foaming agent composition further contains (C) a nonionic compound having a Log P of 0 or more and less than 2.0 (excluding compounds corresponding to component (B)). The method for producing a gypsum hardened body according to claim 12 or 13.