Water-hardening components powder dispersant composition

Abstract

To provide a powder dispersant composition for hydraulic compositions that exhibits excellent heat resistance. [Solution] A powder dispersant composition for hydraulic compositions comprising, as constituent monomers, (A) one or more compounds selected from acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid, and (B) a copolymer containing one or more compounds selected from a compound represented by formula (1) and a compound represented by formula (2), and optionally an alkaline agent, wherein the degree of neutralization of the copolymer is 0.7 or more and 1 or less, and the content of the alkaline agent is 0.3 molar equivalents or less relative to the copolymer. JPEG2026083170000009.jpg56170

Description

Technical Field

[0001] The present invention relates to a powder dispersant composition for hydraulic compositions and a method for producing the same.

Background Art

[0002] In recent years, infrastructure development considering the environment has been aimed at. As an example, the construction of new offshore wind turbines for the utilization of renewable energy and the maintenance and repair of infrastructure established during the period of high economic growth are booming. Conducting infrastructure development from this perspective is considered desirable also from the viewpoints of achieving the SDGs and corporate evaluation based on ESG.

[0003] In fields such as construction and civil engineering where infrastructure development is carried out, hydraulic compositions such as concrete are widely used as repair materials. However, at the work site, due to limited construction space and difficulty in transporting fresh concrete, the use of premixes, which are powder mixtures of hydraulic compositions and organic compounds such as powdered dispersants (hereinafter referred to as powder dispersants), is the mainstream. As powder dispersants premixed with repair materials, there are naphthalene sulfonic acid-based dispersants, polycarboxylic acid-based dispersants, melamine sulfonic acid-based dispersants, etc. In particular, polycarboxylic acid-based dispersants exhibit high dispersibility and contribute to improving the strength of structures by reducing the amount of water incorporated in the hydraulic composition.

[0004] On the other hand, powder dispersants are obtained, for example, by drying a dispersant solution. The powdering methods are roughly classified into a heat drying method that performs drying by heating at normal temperature and normal pressure and a vacuum drying method that performs drying under reduced pressure. Depending on the spreading method of the dispersant solution, they are classified into thin film drying methods typified by drum drying, disk drying, and belt drying methods, spray drying methods, kneader methods, inorganic powder loading methods, etc.

[0005] Patent Document 1 describes a powder dispersant containing a copolymer obtained by polymerizing a specific vinyl monomer (a), such as an ethylene-based unsaturated carboxylic acid derivative having a polyoxyalkylene group, with a specific vinyl monomer (b), such as (meth)acrylic acid, wherein the average number of added moles of oxyalkylene groups or oxystyrene groups having 2 to 4 carbon atoms is 50 to 300, the ratio of monomer (a) to monomer (b) is (a) / [(a)+(b)]×100=10 to 50 (mol%), and at least a portion of the copolymer is a monovalent metal salt.

[0006] Patent Document 2 provides a powdered cement dispersant comprising a polycarboxylic acid copolymer having repeating units (I) derived from an unsaturated polyalkylene glycol ether monomer (a) and repeating units (II) derived from an unsaturated carboxylic acid monomer (b), wherein the degree of neutralization of carboxyl groups contained in the polycarboxylic acid copolymer is 50% or less. The present invention also describes a powdered cement dispersant comprising a polycarboxylic acid copolymer having repeating units (I) derived from an unsaturated polyalkylene glycol ether monomer (a) and repeating units (II) derived from an unsaturated carboxylic acid monomer (b), wherein the unsaturated polyalkylene glycol ether monomer (a) has alkenyl groups having 4 to 8 carbon atoms.

[0007] Patent Document 3 describes a powder dispersant composition for hydraulic compositions containing a copolymer having a constituent unit (1) represented by a specific structural formula (1) and a constituent unit (2) represented by a specific structural formula (2), wherein the median diameter is 1 μm or more and 90 μm or less, and the proportion of particles with a particle size of 1 μm or more and 250 μm or less is 90% by mass or more and 100% by mass or less. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2002-167255 [Patent Document 2] Japanese Patent Publication No. 2008-542159 [Patent Document 3] Japanese Patent Publication No. 2021-102535 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, powdered polycarboxylic acid dispersants, particularly those copolymerized with unsaturated polyalkylene glycol ether compounds, have a problem in that they can burn when exposed to high temperatures during drying, making powdering difficult. This problem of combustion due to heating has not been observed with polycarboxylic acid dispersants copolymerized with unsaturated polyalkylene glycol ester compounds (polycarboxylic acid ester dispersants).

[0010] The present invention provides a powder dispersant composition for hydraulic compositions that contains a polycarboxylic acid copolymer obtained by copolymerizing an unsaturated polyalkylene glycol ether compound and has excellent heat resistance, as well as a method for producing the same. [Means for solving the problem]

[0011] The present invention relates to a powder dispersant composition for hydraulic compositions, comprising as constituent monomers (A) one or more compounds selected from acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid, and (B) a copolymer containing one or more compounds selected from compounds represented by the following general formula (1) and compounds represented by the following general formula (2), and optionally an alkaline agent. The degree of neutralization of the copolymer is 0.7 or more and 1 or less. The amount of the alkaline agent is 0.3 molar equivalents or less relative to the copolymer. This invention relates to a powdered dispersant composition for hydraulic compositions.

[0012] [ka]

[0013] (wherein, R 1 is a hydrogen atom or a methyl group, R 2 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, n is the average number of added moles, and is a number of 5 or more and 150 or less.)

[0014] The powdery dispersant composition for hydraulic composition of the present invention contains, as constituent monomers, 20% by mass or more and 60% by mass or less of a copolymer containing one or more compounds selected from (A) acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid, and one or more compounds selected from (B) the compound represented by the following general formula (1) and the compound represented by the following general formula (2), and is obtained by heating and drying an aqueous solution having a pH of 6 or more and 13 or less, and includes a powdery dispersant composition for hydraulic composition.)

[0015] The present invention also relates to a method for producing a powdery dispersant composition for hydraulic composition, which contains, as constituent monomers, 20% by mass or more and 60% by mass or less of a copolymer containing one or more compounds selected from (A) acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid [hereinafter referred to as monomer (A)] and one or more compounds selected from (B) the compound represented by the above general formula (1) and the compound represented by the above general formula (2) [hereinafter referred to as monomer (B)], and heating and drying an aqueous solution having a pH of 6 or more and 13 or less to obtain a powder of the copolymer.)

Advantages of the Invention

[0016] According to the present invention, there are provided a powdery dispersant composition for hydraulic composition containing a polycarboxylic acid copolymer copolymerized with an unsaturated polyalkylene glycol ether compound and having excellent heat resistance, and a method for producing the same.) The present invention can achieve easy powderization by heating and drying, labor saving in the hydraulic powder mixing step during the production of hydraulic compositions, etc., and can be considered as a technology that can contribute to, for example, SDGs No. 7, 9, 11, 12, 13, etc.)

Embodiments for Carrying Out the Invention

[0017] The inventors of the present invention have found that by limiting the degree of neutralization of a polycarboxylic acid-based dispersant copolymerized with an unsaturated polyalkylene glycol ether compound to a certain value and the content of an alkaline agent in the composition, the heat resistance of the polycarboxylic acid-based dispersant is improved. The reason for such an effect is not necessarily clear, but it is presumed as follows. The combustion of a substance is related to its ease of combination with oxygen and molecular polarity. It is considered that the higher the polarity of a molecule, the more difficult it is to combine with hydrophobic oxygen due to intermolecular interactions and interactions with water, and thus the more difficult it is to burn. In the present invention, by setting the degree of neutralization of a polycarboxylic acid-based dispersant (copolymer of monomers (A) and (B)) having many oxygen atoms in the molecule and an unsaturated polyalkylene glycol ether compound [monomer (B)] in which oxygen combination easily occurs, and a relatively large number of carbon atoms derived from unsaturated alcohol and relatively large energy required for combustion within a predetermined range, ionization and hydration of carboxy groups are promoted, and by increasing the molecular polarity, dehydration and hydration are inhibited and the heat resistance is improved. Further, in the present invention, by limiting the amount of an alkaline agent (such as a neutralizing agent) in the powdery dispersant composition for a hydraulic composition, decomposition of the polycarboxylic acid-based dispersant is suppressed and the performance as a dispersant can also be maintained.

[0018] <## <Powdery Dispersant Composition for Hydraulic Composition> The powdery dispersant composition for a hydraulic composition of the present invention contains, as constituent monomers, one or more compounds selected from (A) acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid [monomer (A)] and one or more compounds selected from (B) the compound represented by the general formula (1) and the compound represented by the general formula (2) [monomer (B)], and contains a copolymer [hereinafter, also referred to as the copolymer of the present invention] having a degree of neutralization of 0.7 or more and less than 1.

[0019] Monomer (A) is one or more compounds selected from acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid. Monomer (A) may be a salt (neutralized product) at the time of charging when producing the copolymer of the present invention. Further, maleic anhydride may be ring-opened after copolymerization and incorporated into the copolymer as maleic acid.

[0020] Monomer (B) is one or more compounds selected from the compounds represented by general formula (1) and the compounds represented by general formula (2). In general formulas (1) and (2), R 1 This is at least one of a hydrogen atom and a methyl group, and it is preferable that it contains a hydrogen atom, i.e., it is either a hydrogen atom or a mixture of a hydrogen atom and a methyl group. In general formulas (1) and (2), R 2 This is at least one elementary atom and an alkyl group having 1 to 3 carbon atoms, with a hydrogen atom being preferred. In general formulas (1) and (2), n is the average number of moles added, and is a number that is 5 or more, preferably 20 or more, more preferably 40 or more, and 150 or less, preferably 120 or less, and more preferably 90 or less. Examples of compounds of general formula (1) include alkylene oxide adducts of 3-methyl-3-buten-1-ol, preferably alkylene oxide adducts selected from ethylene oxide and propylene oxide. Examples of compounds of general formula (2) include alkylene oxide adducts of isoprene alcohol (isoprenol; 3-methyl-3-buten-1-ol), preferably alkylene oxide adducts selected from ethylene oxide and propylene oxide.

[0021] In the copolymer of the present invention, it is preferable that the molar ratio of monomer (A) to monomer (B), which is monomer (A) / monomer (B), is 1 or more, more preferably 3 or more, and 20 or less, and more preferably 10 or less.

[0022] The copolymer of the present invention may contain monomers other than monomer (A) and monomer (B) as constituent monomers, but it is desirable that the proportion of monomer (A) and monomer (B) is high. In the copolymer of the present invention, the total proportion of monomer (A) and monomer (B) in the total constituent monomers is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less, and may be 100 mol%.

[0023] Furthermore, in the copolymer of the present invention, the proportion of monomer (A) in the total of monomer (A) and monomer (B) is preferably 60 mol% or more, more preferably 70 mol% or more, and preferably 95 mol% or less, more preferably 90 mol% or less.

[0024] The copolymer of the present invention may have a weight-average molecular weight of, for example, 20,000 or more, moreover 25,000 or more, moreover 30,000 or more, and also 70,000 or less, 60,000 or less, and moreover 50,000 or less. This weight-average molecular weight was 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 glycol: molecular weights 87,500, 250,000, 145,000, 46,000, 24,000)

[0025] The copolymer of the present invention preferably has a moisture content of 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. Furthermore, the powdered dispersant composition for hydraulic compositions of the present invention has a moisture content of preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. These moisture contents are calculated from the mass before and after drying of the copolymer or powdered dispersant composition for hydraulic compositions of the present invention (hereinafter collectively referred to as the sample) at 105°C for 2 hours, based on the following formula. Drying can be performed, for example, using a forced-air constant-temperature dryer FC-410 (manufactured by Advantec Toyo Co., Ltd.). A predetermined amount of sample, for example 2 g, can be used. Moisture content (mass%) = {Sample mass before drying (g) - Sample mass after drying (g)} / Sample mass before drying (g)

[0026] The degree of neutralization of the copolymer of the present invention is 0.7 or higher, more specifically 0.8 or higher, and 1 or lower, from the viewpoint of the heat resistance of the copolymer.

[0027] The powdered dispersant composition for hydraulic compositions of the present invention optionally contains an alkaline agent. The content of the alkaline agent is 0.3 molar equivalents or less, further 0.2 molar equivalents or less, and further 0.1 molar equivalents or less relative to the copolymer. Examples of alkaline agents include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, ammonia, and alkanolamines. The alkaline agent may be, for example, a neutralizing agent used to neutralize the copolymer of the present invention. For example, an excess neutralizing agent may be added to the copolymer of the present invention (unneutralized product) to neutralize it and produce a copolymer with a degree of neutralization of 1, with the remaining neutralizing agent remaining in the composition within the molar ratio range described above. If the degree of neutralization of the copolymer of the present invention is less than 1, the alkaline agent may not be included. Also, if the degree of neutralization of the copolymer of the present invention is 1, the alkaline agent may be optionally included within the range described above.

[0028] The powder dispersant composition for hydraulic compositions of the present invention may contain the copolymer of the present invention in amounts of, for example, 40% by mass or more, further 60% by mass or more, further 80% by mass or more, and 99% by mass or less, further 95% by mass or less, and further 90% by mass or less.

[0029] The powder dispersant composition for hydraulic compositions of the present invention may optionally contain components other than the copolymer of the present invention. Examples of optional components include hydraulic powder, latent hydraulic powder, fine aggregate, powder defoaming agent, powder shrinkage reducing agent, powder expanding agent, powder effect accelerator, powder effect retarder, powder foaming agent, powder waterproofing agent, and powder rust inhibitor.

[0030] The median diameter (D50) of the copolymer of the present invention may be, for example, 20 μm or more, more specifically 70 μm or more, and 150 μm or less, and more specifically 120 μm or less.

[0031] The median diameter (D50) of the powder dispersant composition for hydraulic compositions of the present invention may be, for example, 20 μm or more, more specifically 70 μm or more, and 150 μm or less, and more specifically 120 μm or less.

[0032] The median diameter (D50) may be measured using a laser diffraction / scattering particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.) with ethanol (ethanol (95), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the dispersion medium, without ultrasonic irradiation.

[0033] <Method for producing a powdered dispersant composition for hydraulic compositions> The present invention relates to a method for producing a powdered dispersant composition for hydraulic compositions (hereinafter also referred to as the "production method of the present invention"), wherein the aqueous solution (also called the "raw material aqueous solution") contains a copolymer comprising monomer (A) and monomer (B) as constituent monomers at a concentration of 20% to 60% by mass, and has a pH of 6 to 13, and is heated and dried to obtain a powder of the copolymer. The manufacturing method of the present invention may appropriately apply the matters described in the description of the powdered dispersant composition for hydraulic compositions of the present invention. Specific examples and preferred examples of monomer (A) and monomer (B) in the manufacturing method of the present invention are the same as those in the powdered dispersant composition for hydraulic compositions of the present invention.

[0034] In the manufacturing method of the present invention, the concentration of the copolymer in the raw material aqueous solution is 20% by mass or more, further 30% by mass or more, 60% by mass or less, and further 40% by mass or less.

[0035] In the manufacturing method of the present invention, the pH of the raw material aqueous solution is adjusted to 6 or higher, then to 8 or higher, then to 13 or lower, and then to 11 or lower. The pH of the raw material aqueous solution can be adjusted, for example, by a neutralizing agent (alkaline agent) used for neutralizing the copolymer.

[0036] In this invention, a raw material aqueous solution for heat drying can be prepared by adding a neutralizing agent (alkaline agent) in an amount of 0.7 molar equivalents or more and 1.3 molar equivalents or less relative to the theoretical neutralization amount of the copolymer to an aqueous solution containing an unneutralized copolymer and water. It is preferable to neutralize the copolymer by adding a predetermined amount of neutralizing agent to the aqueous solution containing the unneutralized copolymer and water in this manner, and then heat-dry the aqueous solution.

[0037] The manufacturing method of the present invention may be a method of obtaining a powder containing the neutralized copolymer by heating and drying the aqueous raw material solution. Furthermore, the manufacturing method of the present invention may be a method of obtaining a powder containing the neutralized copolymer having a degree of neutralization of 0.7 or more and 1 or less by heating and drying the aqueous raw material solution.

[0038] In the manufacturing method of the present invention, it is preferable to obtain a powder containing the copolymer of the present invention having a degree of neutralization of 0.7 or more and 1 or less, and optionally an alkaline agent, wherein the content of the alkaline agent in the powder is 0.3 molar equivalents or less relative to the copolymer.

[0039] Heat drying of the raw material aqueous solution can be performed by spray drying and / or thin film drying. Heat drying preferably includes spray drying. The maximum temperature during spray drying may be 140°C or higher, more preferably 150°C, and 200°C or lower, and more preferably 170°C or lower. Spray drying and thin film drying can each be performed according to known methods.

[0040] In the manufacturing method of the present invention, it is preferable to perform the heat drying until the moisture content in the copolymer powder of the present invention is 5% by mass or less, further 3% by mass or less, and further 1% by mass or less.

[0041] The copolymer and / or powder dispersant composition for hydraulic compositions of the present invention obtained by the manufacturing method of the present invention preferably have a median diameter within the range described above.

[0042] <Embodiments of the Invention> The following are examples of embodiments of the present invention. <1> A powder dispersant composition for hydraulic compositions comprising, as constituent monomers, (A) one or more compounds selected from acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid [hereinafter referred to as monomer (A)], (B) one or more compounds selected from the compounds represented by the following general formula (1) and the compounds represented by the following general formula (2) [hereinafter referred to as monomer (B)], and optionally an alkaline agent, The degree of neutralization of the copolymer is 0.7 or more and 1 or less. The amount of the alkaline agent is 0.3 molar equivalents or less relative to the copolymer. Powdered dispersant composition for hydraulic compositions. [ka]

[0043] <2> In the copolymer, the total proportion of monomer (A) and monomer (B) is 80 mol% or more. <1> A powdered dispersant composition for hydraulic compositions as described above.

[0044] <3> The copolymer is such that the proportion of monomer (A) in the total of monomer (A) and monomer (B) is 60 mol% or more and 95 mol% or less. <1> or <2> A powdered dispersant composition for hydraulic compositions as described above.

[0045] <4> The copolymer has a water content of 5% by mass or less. <1> ~ <3> A powdered dispersant composition for hydraulic compositions as described in any of the above.

[0046] <5> The median diameter (D50) of the copolymer is 20 μm or more and 150 μm or less. <1> ~ <4> A powdered dispersant composition for hydraulic compositions as described in any of the above.

[0047] <6> A method for producing a powdered dispersant composition for hydraulic compositions, comprising: a copolymer containing, as constituent monomers, (A) one or more compounds selected from acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid, and (B) one or more compounds selected from compounds represented by the following general formula (1) and compounds represented by the following general formula (2), at a concentration of 20% to 60% by mass, and an aqueous solution having a pH of 6 to 13, which is heated and dried to obtain a powder of the copolymer. [ka] (In the formula, R 1 R is a hydrogen atom or a methyl group, 2 (where n is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is the average number of moles added, which is between 5 and 150.)

[0048] <7> The heating drying is spray drying and / or thin film drying, <6> A method for producing the powdered dispersant composition for hydraulic compositions described above.

[0049] <8> The above is a case where heat drying is spray drying. <6> or <7> A method for producing the powdered dispersant composition for hydraulic compositions described above.

[0050] <9> The maximum temperature during spray drying is 140°C or higher and 200°C or lower. <8> A method for producing the powdered dispersant composition for hydraulic compositions described above.

[0051] <10> The aqueous solution is prepared by adding a neutralizing agent in an amount of 0.7 molar equivalents or more and 1.3 molar equivalents or less relative to the theoretical neutralization amount of the copolymer. <6> ~ <9> A method for producing a powdered dispersant composition for hydraulic compositions as described in any of the above.

[0052] <11> The heating and drying process is carried out until the moisture content in the copolymer powder is 5% by mass or less. <6> ~ <10> A method for producing a powdered dispersant composition for hydraulic compositions as described in any of the above.

[0053] <12> A powdered dispersant composition for hydraulic compositions, obtained by heating and drying an aqueous solution containing, as constituent monomers, (A) one or more compounds selected from acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid, and (B) one or more compounds selected from compounds represented by the following general formula (1) and compounds represented by the following general formula (2), at a concentration of 20% to 60% by mass, and having a pH of 6 to 13. [ka] (In the formula, R 1 R is a hydrogen atom or a methyl group, 2 (where n is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is the average number of moles added, which is between 5 and 150.) [Examples]

[0054] <Copolymer> Copolymer 1: Acrylic acid / polyethylene glycol (50) isoprenyl ether = 80 moles / 20 moles (the number in parentheses is the average number of moles added, the same applies below), weight-average molecular weight = 30,000. An aqueous solution containing 40% by mass of the unneutralized copolymer was used as the raw material aqueous solution. Copolymer 2: A polymerization solution (unneutralized product) containing a polycarboxylic acid polymer synthesized according to Production Example C1 of Japanese Patent Publication No. 2009-161379 was used as the raw material aqueous solution.

[0055] <Comparative copolymer> Comparative Copolymer 1: Acrylic acid / polyethylene glycol (50) allyl ether = 80 mol / 20 mol copolymer, weight-average molecular weight = 50,000. An aqueous solution containing 40% by mass of the unneutralized copolymer was used as the raw material aqueous solution. Comparative Copolymer 2: Acrylic acid / polyethylene glycol (50) metharyl ether = 80 mol / 20 mol copolymer, weight-average molecular weight = 40,000. An aqueous solution containing 40% by mass of the unneutralized copolymer was used as the raw material aqueous solution.

[0056] <Example 1 and Comparative Example 1> (1) Preparation of aqueous solution of raw materials To an aqueous solution containing the unneutralized copolymer and water, a predetermined amount of 48% sodium hydroxide aqueous solution (manufactured by Kanto Chemical Co., Ltd.) was added as an alkaline agent (neutralizing agent), and the solution was vigorously stirred with a magnetic stirrer to adjust the pH of the raw material aqueous solution and the degree of neutralization (mol%) of the copolymer in the aqueous solution as shown in Table 1, thereby obtaining the raw material aqueous solution.

[0057] (2) Preparation of powder dispersant composition and measurement of moisture content The raw material aqueous solution prepared in (1) was weighed to 0.4 mg in an aluminum pan and subjected to measurement under the following temperature conditions in a nitrogen gas atmosphere of 200 mL / min using TG-DTA (Thermo plus EVO2, manufactured by Rigaku Corporation). The powder dispersant composition was prepared by drying and the loss on ignition was calculated, and the moisture content (%) was calculated based on the following formula. The results are shown in Table 1. The moisture content can be considered as the moisture content in the copolymer after powdering. [1] 30℃ → 100℃(10.0℃ / min) [2] 100℃ → 30℃(-30.0℃ / min) Water content (%) = {Mass of raw material aqueous solution (mg) - Loss on ignition (mg)} × 100 / Mass of raw material aqueous solution (mg)

[0058] (3) Heat resistance of copolymers The powder dispersant composition prepared in (2) was subjected to measurement using TG-DTA (Thermo plus EVO2, manufactured by Rigaku Corporation) under the following temperature conditions in a dry air atmosphere at a flow rate of 200 mL / min, and the exothermic peak temperature (Tm; °C) of DTA due to combustion was recorded. The results are shown in Table 1. Tm can be considered as the Tm in the copolymer after powdering. [1] 30℃ → 500℃(10.0℃ / min) [2] 500℃ → 30℃(-30.0℃ / min)

[0059] [Table 1]

[0060] *1 Molar equivalent relative to the copolymer (the same applies hereafter)

[0061] In Table 1, Examples 1-1 to 1-4, which are dried copolymers containing monomer (A) and monomer (B) as constituent monomers, and in which the degree of neutralization of the copolymer is between 0.7 and 1, showed a higher exothermic peak temperature (Tm; °C) of DTA compared to Comparative Examples 1-1 to 1-4, which used a comparative copolymer. This is thought to be because monomer (B) has a relatively large number of carbon atoms derived from an unsaturated alcohol, and the degree of neutralization of the copolymer of the present invention is within a predetermined range, promoting the ionization and hydration of the carboxyl groups of the copolymer of the present invention, which is relatively difficult to burn, thereby increasing molecular polarity, inhibiting dehydration, and improving heat resistance. However, the mechanism by which the effects of the present invention are exhibited is not limited to this.

[0062] <Example 2 and Comparative Example 2> (I) Production of powder dispersant compositions for hydraulic compositions by spray drying method The raw material aqueous solution prepared in Example 1(1), or the raw material aqueous solution with a modified pH (the neutralizing agent was the same), was spray-dried using a pilot-type powdering facility, and its heat resistance was evaluated. The powdering facility used was equipped with a disc atomizer, a blower, and a dryer. The dryer inlet temperature was 150°C, the outlet temperature was 80°C, the ambient temperature was 20°C, and the disc atomizer rotation speed was 18,000 rpm. If a powder dispersant composition was obtained, the moisture content of the composition was measured using an infrared moisture meter FD-660 (manufactured by Kett Scientific Research Institute Co., Ltd.). If a powder dispersant composition was obtained, the particle size distribution was measured using a laser diffraction / scattering particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.) with ethanol (95) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the dispersion medium, and the median diameter (D50; μm) of the composition was calculated. The results are shown in Table 2. The moisture content can be considered as the moisture content in the copolymer after powdering, and the median diameter can be considered as the median diameter of the copolymer after powdering.

[0063] [Table 2]

[0064] In Table 2, Examples 2-1 and 2-2, which use a dried copolymer containing monomer (A) and monomer (B) as constituent monomers, and in which the degree of neutralization of the copolymer is between 0.7 and 1, exhibited better heat resistance than Comparative Examples 2-1 and 2-2, which use a comparative copolymer, and were obtained as high-quality powder dispersant compositions. This is thought to be due to the improvement in the heat resistance of the copolymer by a mechanism similar to that in Example 1, but the mechanism by which the effects of the present invention are exhibited is not limited to this.

Claims

1. A powder dispersant composition for hydraulic compositions comprising, as constituent monomers, (A) one or more compounds selected from acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid [hereinafter referred to as monomer (A)], (B) a copolymer containing one or more compounds selected from the compounds represented by the following general formula (1) and the compounds represented by the following general formula (2) [hereinafter referred to as monomer (B)], and optionally an alkaline agent, The degree of neutralization of the copolymer is 0.7 or more and 1 or less. The amount of the alkaline agent is 0.3 molar equivalents or less relative to the copolymer. Powdered dispersant composition for hydraulic compositions. 【Chemistry 1】 (In the formula, R １ is at least one of a hydrogen atom and a methyl group, R ２ (where n is a hydrogen atom and at least one alkyl group having 1 to 3 carbon atoms, and n is the average number of moles added, which is between 5 and 150.)

2. The powdered dispersant composition for hydraulic compositions according to claim 1, wherein the total proportion of monomer (A) and monomer (B) in the entire constituent monomers of the copolymer is 80 mol% or more.

3. The powdered dispersant composition for hydraulic compositions according to claim 1 or 2, wherein the copolymer has a copolymer in which the proportion of monomer (A) is 60 mol% or more and 95 mol% or less of the total of monomer (A) and monomer (B).

4. The powdered dispersant composition for hydraulic compositions according to any one of claims 1 to 3, wherein the moisture content of the copolymer is 5% by mass or less.

5. The powdered dispersant composition for hydraulic compositions according to any one of claims 1 to 4, wherein the median diameter (D50) of the copolymer is 20 μm or more and 150 μm or less.

6. A powdered dispersant composition for hydraulic compositions, obtained by heating and drying an aqueous solution containing, as constituent monomers, (A) one or more compounds selected from acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, and maleic acid, and (B) one or more compounds selected from compounds represented by the following general formula (1) and compounds represented by the following general formula (2) at a concentration of 20% to 60% by mass, wherein the pH is 6 to 13. 【Chemistry 2】 (In the formula, R １ R is a hydrogen atom or a methyl group, ２ (where n is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is the average number of moles added, which is between 5 and 150.)

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