Granularizing agent for fresh concrete

Abstract

The objective of the present invention is to provide a granulating agent for fresh concrete that has excellent granulating performance for fresh concrete. The present invention relates to a granulating agent for fresh concrete containing (i) a polymer that exhibits an acidic pH when made into an aqueous solution or dispersion, or (ii) a salt of the polymer.

Description

[Technical Field]

[0001] This invention relates to a technology for granulating fresh concrete. [Background technology]

[0002] Fresh concrete (commonly known as ready-mix concrete) is typically produced at a ready-mix concrete plant and then transported to the construction site by mixer trucks. However, unused fresh concrete (so-called leftover concrete) is frequently generated during this process, and some of this leftover concrete is returned to the ready-mix concrete plant (referred to as "returned concrete"). In practice, leftover concrete and ready-mix concrete are usually washed and separated (sludge, neutralized water, stones, and sand) and then landfilled as industrial waste. However, this process involves considerable labor and expense, and also generates a large amount of industrial waste. In Japan, approximately 2-5% of ready-mix concrete shipments are leftover concrete and ready-mix concrete. In response to the above issues, mechanisms for actively reusing leftover and returned concrete are being considered. Specifically, this involves adding and mixing treatment agents for leftover and returned concrete (e.g., leftover concrete buster, re-con zero evo, Nichimo's leftover concrete treatment agent, etc.) with the leftover or returned concrete to generate granular material, which is then reused as new building material (e.g., bedding material, roadbed material, civil engineering structures, buildings). This mechanism is currently one of the most promising initiatives as it is expected to contribute to the circular economy.

[0003] The technology related to the above-mentioned treatment agent is also described in the following literature. Patent Document 1 below describes a technique for granulating a fresh cement composition by adding and mixing a highly absorbent polymer (such as anionic polyacrylamide) and a rapid-setting agent. Patent Document 2 below describes a method for granulating surplus fresh concrete by adding a high-molecular-weight granulating agent, mainly composed of anionic polyacrylamide, to surplus fresh concrete and stirring it.

[0004] However, at present, it is difficult to say that the reuse of residual concrete and returned concrete is being fully carried out, and there is an urgent need to expand the types of treatment agents for residual concrete and returned concrete and improve the convenience and functions in their use so that such reuse can be actively carried out.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a granulating agent for fresh concrete that is excellent in the granulating performance of fresh concrete.

Means for Solving the Problems

[0007] As a result of intensive studies, the present inventor has found that a specific polymer has excellent performance in granulating fresh concrete. Based on this finding, the present inventor has completed the following present invention.

[0008] Preferred configurations of the present invention are described in the following (1) to (10) and the like. (1) A granulating agent for fresh concrete containing (i) a polymer that exhibits an acidic pH when in an aqueous solution or aqueous dispersion or (ii) a salt of a polymer. (2) The granulating agent for fresh concrete according to (1) above, wherein the polymer (a polymer that exhibits an acidic pH and / or a salt of a polymer) is emulsified in a solution. (3) The granulating agent for fresh concrete according to (1) or (2) above, wherein the polymer contains a structural unit having a carboxyl group. (4) The granulating agent for fresh concrete according to any one of (1) to (3) above, wherein the polymer is a copolymer further having a hydrophobic structural unit. (5) The granulating agent for fresh concrete according to any one of (1) to (4) above, which contains a polymer that exhibits an acidic pH when in an aqueous solution or an aqueous dispersion, and the polymer exhibits a pH of 2.0 to 5.0 when in a 10.0% by mass aqueous solution or aqueous dispersion at 25.0 °C. (6) The granulating agent for fresh concrete according to any one of (1) to (5) above, wherein the weight average molecular weight of the polymer is 1,000 to 10,000,000. (7) The granulating agent for fresh concrete according to any one of (1) to (6) above, which contains a polymer that exhibits an acidic pH when in an aqueous solution or an aqueous dispersion, and the polymer is emulsified with water as the dispersion medium. (8) The granulating agent for fresh concrete according to any one of (1) to (7) above, which does not contain a flash setting accelerator. (9) A method for forming a granulated product, which includes a step of adding the granulating agent according to any one of (1) to (8) above to fresh concrete, stirring, and then curing the mixture. (10) An agglomerated product containing the granulating agent according to any one of (1) to (8) above and cement.

Effects of the Invention

[0009] The granulating agent for fresh concrete of the present invention has excellent granulating performance for fresh concrete.

Modes for Carrying Out the Invention

[0010] Hereinafter, matters related to the granulating agent for fresh concrete of the present invention, its usage method, and the composition containing it will be described in detail. However, the following description is an exemplification for explaining the present invention, and the present invention is not intended to be particularly limited only to this description range.

[0011] (polymer) The granulating agent for fresh concrete of the present invention contains a polymer or a salt of a polymer that exhibits an acidic pH when prepared as an aqueous solution or aqueous dispersion, preferably a polymer that exhibits an acidic pH when prepared as an aqueous solution or aqueous dispersion, and more preferably a polymer that exhibits an acidic pH when prepared as an aqueous dispersion. In this specification, an acidic pH means a pH value less than 7.0, and an basic pH means a pH value greater than 7.0. The above-mentioned polymer exhibiting an acidic pH exhibits an acidic pH when prepared as a 10.0% by mass aqueous solution or aqueous dispersion at 25.0°C, preferably with a pH of 2.0 to 6.0, more preferably with a pH of 2.0 to 5.0, and even more preferably with a pH of 2.0 to 4.0. The above pH can be measured by the method described in the examples. Furthermore, the above-mentioned aqueous solution or aqueous dispersion can be prepared by known appropriate methods, such as dissolving or dispersing the polymer in distilled water to a predetermined concentration. Furthermore, the salt of the polymer is a salt obtained by neutralizing a polymer that exhibits an acidic or basic pH when prepared as an aqueous solution or aqueous dispersion, and preferably a salt obtained by neutralizing the polymer that exhibits an acidic pH when prepared as an aqueous solution or aqueous dispersion. Specific examples of the salt include sodium salt, potassium salt, magnesium salt, calcium salt, aluminum salt, etc., but sodium salt is preferred.

[0012] (Structural units having acidic functional groups) The polymers in this invention that exhibit an acidic pH when prepared as an aqueous solution or aqueous dispersion contain one or more structural units having acidic functional groups. Examples of the acidic functional group include a carboxyl group, a sulfonic acid group, a phosphoric acid group, a phosphate group, a phosphorous acid group, and a hydroxyl group, with a carboxyl group, a sulfonic acid group, or a phosphoric acid group being preferred, and a carboxyl group being more preferred.

[0013] [ka] A concrete example of a structural unit having the above-mentioned acidic functional group is the structural unit represented by formula (I) above. In the above equation (I), R 1 ~R 4 One or more of the R are acidic functional groups, and the others are R 1 ~R 4 However, they are the same or different hydrogen atoms or unsubstituted or substituted monovalent hydrocarbon groups having 1 to 8 carbon atoms. In the above formula (I), preferably R 1 ~R 4 One or two of them are acidic functional groups, and more preferably one is an acidic functional group. Other R's mentioned above 1 ~R 4 Preferably, two or more of them are hydrogen atoms, and more preferably, all of them are hydrogen atoms. The above unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms is preferably an unsubstituted monovalent hydrocarbon group having 1 to 4 carbon atoms. More specifically, the unsubstituted monovalent hydrocarbon group includes linear, branched, or cyclic alkyl groups, alkenyl groups, aryl groups, aralkyl groups, etc., preferably alkyl groups, and particularly preferably methyl groups. The above substituted monovalent hydrocarbon group has some or all of its hydrogen atoms substituted with substituents, and examples of such substituents include alkoxy groups such as methoxy groups, ethoxy groups, and (iso)propoxy groups, and halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. The structural unit represented by formula (I) above may be a structural unit formed when the carbon-carbon double bond of an unsaturated carboxylic acid monomer is cleaved. Examples of such unsaturated carboxylic acid monomers include acrylic acid, methacrylic acid, crotonic acid, tigric acid, 3-methylcrotonic acid, 2-methyl-2-pentenoic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, and 2-methyleneglutaric acid. Preferably, it is acrylic acid, methacrylic acid, maleic acid, or fumaric acid, and more preferably acrylic acid. In the present specification, unless otherwise specified, the acidic functional group is in an unneutralized state.

[0014] (Hydrophobic structural unit) The polymer in the present invention is preferably a copolymer containing one or more hydrophobic structural units. The hydrophobic structural unit does not have the above acidic functional group and is a structural unit derived from a hydrophobic monomer having a solubility parameter of the homopolymer of 15 or less. The solubility parameter is a value calculated by the method described on pages 147 - 154 of "POLYMER ENGINEERING AND SCIENCE" (1974, Vol.14, No.2). The method will be outlined below. The solubility parameter (δ) (cal / cm 3 ) 1 / 2 of the homopolymer is calculated by the following calculation method based on the evaporation energy (△ei) and molar volume (△vi) of the constituent units forming the polymer. δ = (△ei / △vi) 1 / 2 (cal / cm 3 ) 1 / 2 . The solubility parameter is preferably 14 or less, more preferably 13 or less, still more preferably 12 or less, and particularly preferably 11 or less. The solubility parameter is usually 5 or more.

[0015] Examples of hydrophobic monomers include esters (or (meth)acrylates) of (meth)acrylic acid with optionally substituted alcohols; aromatic vinyl monomers such as styrene; olefin monomers such as propylene; esters of unsaturated alcohols such as vinyl acetate with carboxylic acids; vinyl halides such as vinyl chloride; alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; addition products of unsaturated monomers having a cyclic ether-containing group with 2 to 8 carbon atoms, such as 1-allyloxy-3-butoxypropan-2-ol, with alcohols having 1 to 20 carbon atoms; alkylene oxide adducts of unsaturated alcohols with 2 to 20 carbon atoms, such as ethylene oxide adducts of allyl alcohol, ethylene oxide adducts of metharyl alcohol, and ethylene oxide adducts of isoprenol, and their terminally hydrophobic modified products; and cyclic vinyl monomers such as N-vinylpyrrolidone.

[0016] It is preferable that the hydrophobic structural unit does not have hydrophilic functional groups.

[0017] [ka] A preferred example of the hydrophobic structural unit described above is the structural unit represented by formula (II) above. In formula (II) above, R 5 ~R 8 These are identical or different hydrogen atoms, unsubstituted or substituted monovalent hydrocarbon groups having 1 to 8 carbon atoms, or -COOM 1 (M 1 ( is a monovalent hydrocarbon group having 1 to 8 carbon atoms), preferably R 5 ~R 8 One of them is -COOM 1 And the remaining R 5 ~R 8 is a hydrogen atom or an unsubstituted monovalent hydrocarbon group having 1 to 4 carbon atoms, more preferably R 5 ~R 8 One of them is -COOM 1 And the remaining R 5 ~R 8 That is a hydrogen atom. The above M 1The group is preferably a methyl group, an ethyl group, a propyl group, or a butyl group, and more preferably an ethyl group. More specifically, the unsubstituted monovalent hydrocarbon groups mentioned above include linear, branched, or cyclic alkyl groups, alkenyl groups, aryl groups, aralkyl groups, etc., with alkyl groups being preferred, and methyl groups being particularly preferred. The substituted monovalent hydrocarbon groups mentioned above have some or all of their hydrogen atoms substituted with substituents, and examples of such substituents include alkoxy groups such as methoxy groups, ethoxy groups, and (iso)propoxy groups. The structural unit represented by formula (II) above may be a structural unit formed when the carbon-carbon double bond of a hydrophobic monomer is cleaved. Examples of such hydrophobic monomers include styrene, acrylic acid esters, and methacrylic acid esters, but preferably acrylic acid esters or methacrylic acid esters, and more preferably acrylic acid esters. Specifically, examples include methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, but ethyl acrylate is particularly preferred.

[0018] [ka] Furthermore, as a preferred example of the hydrophobic structural unit described above, there is also the structural unit represented by formula (III) above. In formula (III) above, X is C=O or (CH2)p [p is an integer from 0 to 5], and R 12 is a hydrocarbon group having 2 to 8 carbon atoms, m is an integer from 5 to 300, and R 13 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 8 carbon atoms, and the remaining R 9 ~R 11 These are identical or different hydrogen atoms, and unsubstituted or substituted monovalent hydrocarbon groups having 1 to 8 carbon atoms. The above p is preferably an integer between 0 and 2, and more preferably 0. The above X is preferably C=O or (CH2)2, and more preferably C=O. 12is preferably a hydrocarbon group having 2 to 4 carbon atoms, and more preferably C2H4. The above m is preferably an integer from 5 to 150, and more preferably an integer from 8 to 90. 13 The remaining R is preferably a hydrogen atom or a monovalent hydrocarbon having 1 to 4 carbon atoms, and more preferably CH3. 9 ~R 11 is preferably a hydrogen atom or a monovalent hydrocarbon group having 2 to 4 carbon atoms, and more preferably R 9 ~R 11 One of them is a monovalent hydrocarbon group with 2 to 4 carbon atoms (preferably a methyl group), and the remaining R 9 ~R 11 That is a hydrogen atom. The structural unit represented by formula (III) above may be a structural unit formed when a monomer containing a polyalkylene glycol group (hydroxyl group-terminated), an alkoxypolyalkylene glycol group (alkyl group-terminated), or a phenoxypolyalkylene glycol group (aryl group-terminated) (hereinafter referred to as a polyalkylene glycol group-containing monomer) undergoes carbon-carbon double bond cleavage. Examples of such polyalkylene glycol group-containing monomers include polyalkylene glycol monomethacrylate, polyalkylene glycol monoacrylate, alkoxypolyalkylene glycol monomethacrylate, alkoxypolyalkylene glycol monoacrylate, phenoxypolyalkylene glycol monomethacrylate, and the like. Preferably, it is alkoxypolyalkylene glycol monomethacrylate or alkoxypolyalkylene glycol monoacrylate, and more preferably alkoxypolyalkylene glycol monomethacrylate. Examples of the above-mentioned alkoxypolyalkylene glycol monomethacrylate include methoxypolyethylene glycol-methacrylate, octoxypolyethylene glycol-polypropylene glycol-methacrylate, lauroxypolyethylene glycol-methacrylate, and stearoxypolyethylene glycol-methacrylate, with methoxypolyethylene glycol-methacrylate being preferred. Examples of the above-mentioned phenoxypolyalkylene glycol monomethacrylate include phenoxypolyethylene glycol-methacrylate. Examples of the above-mentioned alkoxypolyalkylene glycol monoacrylate include methoxypolyethylene glycol acrylate. Examples of the above-mentioned phenoxypolyalkylene glycol monoacrylate include nonylphenoxypolypropylene glycol acrylate and nonylphenoxypolyethylene glycol polypropylene glycol acrylate. Examples of the above-mentioned polyalkylene glycol monomethacrylates include polyethylene glycol-monomethacrylate, polypropylene glycol-monomethacrylate, polyethylene glycol-propylene glycol-monomethacrylate, polyethylene glycol-tetramethylene glycol-monomethacrylate, and propylene glycol-polybutylene glycol-monomethacrylate. Examples of the above-mentioned polyalkylene glycol monoacrylates include polyethylene glycol monoacrylate and polypropylene glycol monoacrylate. Furthermore, as an example of monomers containing polyalkylene glycol groups other than those mentioned above, compounds obtained by adding ethylene oxide to the hydroxyl group of 3-methyl-3-buten-1-ol (isoprenol) (for example, with an average of 50 moles of ethylene oxide added) can also be cited.

[0019] (Neutralized structural units) The polymer salt in the present invention preferably contains one or more structural units having neutralized acidic or basic functional groups. More preferably, it contains structural units having neutralized acidic functional groups. Preferred examples of structural units having acidic functional groups are as described above, and the polymer salt in the present invention can be obtained by neutralizing them to form a salt. Examples of such basic functional groups (unneutralized) include amino groups, etc. In the polymer salt of the present invention, the ratio of neutralized structural units having acidic or basic functional groups (mol) to neutralized and unneutralized structural units having acidic or basic functional groups (mol), i.e., the ratio of neutralized structural units having acidic or basic functional groups (e.g., structural units derived from sodium acrylate (mol)) / neutralized and unneutralized structural units having acidic or basic functional groups (e.g., the total of structural units derived from sodium acrylate and acrylic acid (mol)), is preferably 0.2 or more, more preferably 0.3 or more, and even more preferably 0.4 or more. Furthermore, the above ratio is preferably 0.8 or less, and more preferably 0.6 or less.

[0020] The polymer salt in this invention may be an aqueous solution or an aqueous dispersion from the viewpoint of ease of handling. With respect to the polymer salts in the present invention, if the polymer salt has structural units having neutralized acidic or basic functional groups and exhibits an acidic pH when prepared as an aqueous solution or aqueous dispersion, it is understood to be (i) a polymer exhibiting an acidic pH when prepared as an aqueous solution or aqueous dispersion in the present invention. Furthermore, if the polymer salt has structural units having neutralized acidic or basic functional groups and exhibits a neutral or basic pH when prepared as an aqueous solution or aqueous dispersion, it is understood to be (ii) a polymer salt in the present invention.

[0021] In the present invention, an aqueous dispersion is one in which a polymer or a salt of a polymer, which is the dispersed phase, is uniformly dispersed in water, which is the dispersion medium. For example, a general emulsion falls under this category. In other words, the aqueous dispersion of this invention refers to one in which the dispersed phase does not separate, settle, or aggregate from the water, which is the dispersion medium. For example, a superabsorbent polymer, such as the one described in Patent Document 1, which absorbs water and becomes a gel when mixed with water, cannot form an aqueous solution or aqueous dispersion in the present invention. In other words, it is preferable that the polymer of (i) or the salt of the polymer of (ii) that forms the aqueous dispersion in the present invention does not contain a superabsorbent polymer, and a form in which the granulating agent of the present invention does not contain a superabsorbent polymer is also one of the preferred embodiments of the present invention. Here, a superabsorbent polymer is defined as a polymer with a CRC (water absorption ratio under no pressure) of 5 [g / g] or more, as specified in ERT441.2-02.

[0022] In the present invention, when the polymer is in an aqueous solution or aqueous dispersion, it is preferable that the amount of precipitates and aggregates is 1% by mass or less relative to 100% by mass of the polymer. More preferably, it is 0.5% by mass or less, even more preferably 0.1% by mass or less, particularly preferably 0.01% by mass or less, and most preferably 0% by mass. The aforementioned precipitates and aggregates refer to substances that precipitate or aggregate when a polymer or a salt of a polymer is mixed with an equal weight of water, and do not refer to aqueous solutions or aqueous dispersions. The amount of the sediment and aggregate can be measured by the following method. First, the polymer or polymer salt is mixed with an equal weight of water, and the mixture is filtered using a stainless steel mesh (100 mesh (opening 0.154 mm)) to obtain a filtrate. The obtained filtrate is dried in a hot air dryer at a temperature of 110°C for 1 hour, and the resulting residue is divided into precipitate and aggregate, and formula: Amount of precipitate / aggregates (mass%) = ([mass of residue] ÷ [mass of polymer or polymer salt]) × 100 (%) It can also be calculated based on this.

[0023] (Other structural units) The polymer in the present invention may contain structural unit (IV) other than the structural unit described above in the remainder.

[0024] (Composition of polymers) The polymer in the present invention preferably contains 10.0 to 90.0% by mass of the above-mentioned acidic functional group-containing structural unit (I) relative to the total mass of the polymer. More preferably, it contains 20.0 to 60.0% by mass, and even more preferably, 30.0 to 50.0% by mass. Furthermore, the polymer in the present invention preferably contains 10.0 to 90.0% by mass of the above-mentioned hydrophobic structural unit (II) relative to the total mass of the polymer. More preferably, it contains 30.0 to 70.0% by mass, and even more preferably, 40.0 to 60.0% by mass. Furthermore, the polymer in the present invention preferably contains 1.0 to 40.0% by mass, preferably 2.0 to 30.0% by mass, of the above-mentioned hydrophobic structural unit (III) relative to the total mass of the polymer. The mass percentage of the above structural unit (I) is the mass percentage on an acidic form basis. In this invention, "acid type conversion" means that when calculating the mass ratio (composition ratio) of structural units (I) having acidic functional groups relative to the total mass of the polymer, the calculation is performed using the corresponding acid type structural unit. For example, when calculating the mass ratio of structural units derived from sodium acrylate relative to the total mass of the polymer, it means that the mass calculation is performed using the corresponding acid type structure, which is derived from acrylic acid.

[0025] The content of structural units other than structural units (I), (II), and (III), namely structural unit (IV), is preferably 0 to 10% by mass relative to the total mass of the polymer. More preferably, it is 0 to 5% by mass, even more preferably 0 to 1% by mass, and most preferably 0% by mass.

[0026] The polymer in the present invention preferably contains a structural unit (I) having an acidic functional group and a hydrophobic structural unit (II), more preferably contains a structural unit (I) having an acidic functional group, a hydrophobic structural unit (II), and a hydrophobic structural unit (III), and is even more preferably composed of these. Some examples of polymers in the present invention include, for example, (I) polymers polymerized using acrylic acid or methacrylic acid, copolymers polymerized using (II) alkyl (having 1 to 8 carbon atoms) acrylates in addition to (I), copolymers polymerized using (III) monomers containing polyalkylene glycol groups in addition to (I) and (II), and (IV) polymers polymerized after neutralizing all or part of the acrylic acid or methacrylic acid used. The polymer in this invention preferably contains substantially no structural units having basic functional groups (unneutralized) or amide groups.

[0027] The polymer in the present invention has a weight-average molecular weight (Mw) of 1,000 to 10,000,000, preferably 2,000 to 8,000,000, more preferably 3,000 to 6,000,000, and even more preferably 4,000 to 5,000,000, calculated on a polystyrene basis by gel permeation chromatography (GPC). In one embodiment, the polymer may have a weight-average molecular weight of 10,000 to 2,500,000, preferably 50,000 to 1,000,000, more preferably 100,000 to 800,000, and even more preferably 200,000 to 600,000. The glass transition temperature of the polymer in the present invention may be, for example, -40°C or higher, preferably -30°C or higher, more preferably -20°C or higher, and particularly preferably -10°C or higher, from the viewpoint of film-forming properties and the like. Furthermore, the upper limit of the glass transition temperature of the polymer in this disclosure may be, for example, 80°C or lower, preferably 75°C or lower, more preferably 65°C or lower, and particularly preferably 50°C or lower. Furthermore, the glass transition temperature is determined using the glass transition temperature of the monomer homopolymer used in the monomer components that make up the polymer. Formula (I): 1 / Tg=Σ(Wm / Tgm) / 100 (I) The temperature may also be determined based on Fox's formula, which is expressed as follows: [wherein Wm represents the content (mass%) of monomer m in the monomer components constituting the polymer, and Tgm represents the glass transition temperature (absolute temperature: K) of the monomer m homopolymer].

[0028] The acid value of the polymer in the present invention is, for example, 50 mg KOH / g or more, preferably 100 mg KOH / g or more, more preferably 150 mg KOH / g or more, and even more preferably 180 mg KOH / g or more. The upper limit of the acid value is, for example, 500 mg KOH / g or less, preferably 400 mg KOH / g or less, and more preferably 300 mg KOH / g or less. The acid value of the polymer in this disclosure is determined, for example, by measuring the acid value (mgKOH / g) per gram of polymer solids in accordance with JIS K0070:1992 using an automatic titrator (product name: COM-555, manufactured by Hiranuma Sangyo Co., Ltd.).

[0029] In 100 parts by mass of the granulating agent for fresh concrete of the present invention, the total content of the polymer and the polymer salt is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. The solid content (non-volatile content) in 100 parts by mass of the granulating agent for fresh concrete of the present invention is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. The solid content (non-volatile content) of the present invention can be determined by known methods. For example, 1 g of granulating agent is weighed, dried in a hot air dryer at a temperature of 110°C for 1 hour, and the resulting residue is used as the non-volatile content, and the formula is: Non-volatile content (mass%) of granulating agent = ([mass of residue] ÷ [1g of granulating agent]) × 100 (%) It can also be calculated based on this.

[0030] (Emulsion) The granulating agent for fresh concrete of the present invention may be a liquid in which the polymer described above is simply dissolved or dispersed in a solvent, but it is particularly desirable that the polymer be in the form of an emulsion in which it is covered with an emulsifier and granulated (micelle-formed). Examples of such emulsions include O / W type (oil-in-water), W / O type (water-in-oil), O / W / O type (oil-in-water), and W / O / W type (water-in-oil). Preferably, the O / W type or W / O type is preferred, and more preferably the O / W type. For example, in the case of the superabsorbent polymer described in Patent Document 1, since it is used in powder form, there is a need to improve the handling when mixing it with fresh concrete. By using an O / W type emulsion, it is possible to achieve excellent workability during spraying, suppress rapid thickening when added to fresh concrete, and expect homogeneous granulation. Furthermore, although the anionic polyacrylamide polymer described in Patent Document 2 is an emulsion, it is a water-in-oil emulsion, and therefore improvements were needed from an environmental protection standpoint. In contrast, when the granulating agent of the present invention is an O / W type emulsion, the environmental burden can be further reduced. Examples of dispersion media for the emulsion include water, oil, and alcohol, but water is preferred. The solid content (polymer and emulsifier) ​​is present in an amount of 1.0 to 80.0% by mass, preferably 10.0 to 50.0% by mass, and more preferably 20.0 to 40.0% by mass, based on the total mass of the emulsion. Examples of emulsifiers used in the production of emulsions include anionic emulsifiers, nonionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers, and polymer emulsifiers. These emulsifiers may be used individually or in combination of two or more types. It is desirable that the emulsifier be present in the emulsion at an amount of 1.0 to 20.0% by mass, preferably 1.0 to 5.0% by mass, relative to the total mass of the polymer contained therein. The viscosity of the above emulsion is, for example, 500 mPa·s or less, preferably 1 to 400 mPa·s, and more preferably 5 to 300 mPa·s. The viscosity of the above emulsion can be measured using a Type B rotational viscometer (rotor No. 2) under the conditions of 25°C and 60 rpm. Furthermore, the above emulsion should preferably have a pH of 2.0 to 4.0. Known methods can be used to measure the pH of the emulsion. For example, one method is to measure it at 25°C using a pH meter (LAQUA, manufactured by Horiba, Ltd.) in accordance with JIS Z8802. The average particle diameter of the particles (micelles) in the emulsion in the present invention may be, for example, 30 nm or more, preferably 50 nm or more, and the upper limit of the average particle diameter of the emulsion particles may be, for example, 3,000 nm or less, preferably 1,000 nm or less. The average particle diameter of the emulsion particles may be the volume-average particle diameter measured using a particle size distribution analyzer by dynamic light scattering [Particle Sizing Systems, product name: NICOMP Model 380].

[0031] The emulsifiers mentioned above are not particularly limited, but include, for example, anionic emulsifiers (e.g., alkyl sulfate salts such as ammonium dodecyl sulfate and sodium dodecyl sulfate; alkyl sulfonate salts such as ammonium dodecyl sulfonate and sodium dodecyl sulfonate; alkylaryl sulfonate salts such as ammonium dodecylbenzene sulfonate and sodium dodecylnaphthalene sulfonate; polyoxyethylene alkyl sulfate salts; polyoxyethylene alkylaryl sulfate salts; polyoxyethylene alkyl ether sulfates; dialkyl sulfosuccinates; aryl sulfonic acid-formaldehyde condensates; fatty acid salts such as ammonium laurylate and sodium stearate, etc.), and nonionic emulsifiers (e.g., polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, condensates of polyethylene glycol and polypropylene glycol, sorbitan fatty acid ethers) Examples of emulsifiers include polyoxyethylene sorbitan fatty acid esters, fatty acid monoglycerides, condensates of ethylene oxide and aliphatic amines, etc.), cationic emulsifiers (e.g., dialkyldimethylammonium salts, ester-type dialkylammonium salts, amide-type dialkylammonium salts, dialkylimidazolinium salts, etc.), amphoteric emulsifiers (e.g., alkyldimethylaminoacetic acid betaine, alkyldimethylamine oxide, alkylcarboxymethylhydroxyethylimidazolinium betaine, alkylamidopropyl betaine, alkylhydroxysulfobetaine, etc.), polymer emulsifiers (e.g., polyvinyl alcohol and its modified products; (meth)acrylic acid-based water-soluble polymers; hydroxyethyl (meth)acrylic acid-based water-soluble polymers; hydroxypropyl (meth)acrylic acid-based water-soluble polymers; polyvinylpyrrolidone, etc.), and preferably anionic emulsifiers, and more preferably polyoxyethylene alkyl ether sulfates.

[0032] (Method for manufacturing emulsion) The method for producing the emulsion containing the above polymer is not particularly limited, but for example, it may be produced by emulsion polymerization of the monomer components that are raw materials for the polymer in a solvent. Examples of solvents include aqueous solvents such as water and water-containing solvents [for example, a mixed solvent of water and alcohol (for example, C1-4 alcohols such as methanol and ethanol)]. One or more solvents may be used. There are no particular limitations on the method for emulsion polymerization of monomer components, but examples include polymerizing by dropping the monomer components into a solvent containing an emulsifier, or polymerizing by dropping monomer components that have been previously emulsified with an emulsifier into a solvent. Specific examples of emulsifiers include those listed above. One or more types of emulsifiers may be used. Furthermore, the emulsifier may be either a non-reactive or reactive emulsifier, but from the viewpoint of emulsion particle stability, a non-reactive emulsifier is preferred, and a non-reactive anionic emulsifier is more preferred. The amount of solvent should be set appropriately, taking into consideration the amount of non-volatile components contained in the resulting emulsion.

[0033] Polymerization may be carried out in the presence of a polymerization initiator. Examples of polymerization initiators include azo compounds such as azobisisobutyronitrile, 2,2-azobis(2-methylbutyronitrile), 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(2-diaminopropane)hydrochloride, 4,4-azobis(4-cyanovaleric acid), and 2,2-azobis(2-methylpropionamidine); persulfates such as potassium persulfate; and peroxides such as hydrogen peroxide, benzoyl peroxide, parachlorobenzoyl peroxide, lauroyl peroxide, and ammonium peroxide. Polymerization initiators may be used individually or in combination of two or more.

[0034] The amount of polymerization initiator used can be set appropriately depending on the type of polymerization initiator, etc., and is not particularly limited, but may be, for example, 0.05 parts by mass or more, preferably 0.1 parts by mass or more, per 100 parts by mass of monomer component, or for example, 2 parts by mass or less, preferably 1 part by mass or less. The method of adding the polymerization initiator is not particularly limited, but examples include batch addition, divided addition, and continuous dropwise addition.

[0035] The polymerization reaction may be carried out in the presence of a reducing agent (e.g., sodium bisulfite), a decomposing agent for polymerization initiators (e.g., a transition metal salt such as ferrous sulfate), a chain transfer agent (e.g., a compound having a thiol group (e.g., tert-dodecyl mercaptan)), a pH buffer, a chelating agent, etc., as needed. The atmosphere during polymerization is not particularly limited, but from the viewpoint of polymerization efficiency, an inert gas such as nitrogen gas may be used.

[0036] The polymerization temperature is not particularly limited, but may be, for example, 50 to 100°C, preferably 60 to 95°C. The polymerization temperature may be constant or may be changed during the polymerization reaction. The polymerization time is not particularly limited and may be set appropriately according to the progress of the polymerization reaction, but may be, for example, 1 hour or more (e.g., 1 to 24 hours), preferably 2 to 12 hours (e.g., 2 to 9 hours).

[0037] (Granulating agent) The granulating agent for fresh concrete of the present invention is particularly expected to be used in processes in which granular material is formed by adding it to fresh concrete, stirring it, and then curing the mixture. The present invention also involves the use of (i) a polymer that exhibits an acidic pH when prepared as an aqueous solution or aqueous dispersion, or (ii) a salt of the polymer, for granulation of fresh concrete. A method for forming granular material, which includes the step of adding the above-mentioned granulating agent to fresh concrete, stirring it, and then curing the mixture, is also one of the present inventions. Furthermore, a method for producing granular material, which includes the steps of adding the above-mentioned granulating agent to fresh concrete and curing the mixture obtained in the addition step, is also one of the present invention. Fresh concrete refers to concrete that has been mixed with cement and water but has not yet hardened. In this invention, the water-cement ratio (W / C%) is 20-60%, preferably 30-55%, and more preferably 40-50%. The above granulating agent is used in 1 m³ of fresh concrete. 3 It is desirable to add the granulating agent in the range of 0.5 to 5.0 kg per unit area. The above stirring can be done in a drum at 10 to 60 rpm for about 2 to 10 minutes, and the above curing can be done by leaving it in the open air for at least 1 hour. As a more specific example of the assumed usage process of the granulating agent of the present invention, it is conceivable to add the granulating agent to a mixer (e.g., a ready-mix concrete truck) that has already been fed fresh concrete and stir it, then discharge the fresh concrete after stirring, or discharge the remaining concrete into a waste pit, add the agent and stir and mix it by hand or with heavy machinery, and then cure it. Furthermore, the granulating agent for fresh concrete of the present invention may contain rapid setting accelerators such as sodium silicate, calcium aluminate, aluminum sulfate, sodium aluminate, and alumina cement, but may also not contain them. The content of the rapid setting accelerator in the above-mentioned granulating agent is preferably 1% by mass or less per 100% by mass of the granulating agent. More preferably it is 0.5% by mass or less, even more preferably 0.1% by mass or less, and most preferably 0% by mass. A form in which the above-mentioned granulating agent does not contain a rapid setting accelerator is one of the preferred embodiments of the present invention.

[0038] (granules) By using the granulating agent of the present invention in fresh concrete, granular material containing the granulating agent of the present invention and cement is produced. This granular material is expected to be reused as a new building material (e.g., paving material, roadbed material, civil engineering structure, building). Therefore, it is desirable that the granular material has a major diameter of 60 mm or less, preferably 50 mm or less, and contains aggregates of 5 mm or more (equivalent to coarse aggregate) and aggregates of 5 mm or less (equivalent to fine aggregate), and that these can be separated and used. [Examples]

[0039] The present invention will now be described in more detail based on examples, but the present invention is not limited to these examples. In the following, unless otherwise specified, "parts" means "parts by mass".

[0040] <Manufacturing Example 1: Manufacturing of a polymer that is a cement dispersant 1> 80.0 parts of deionized water were placed in a glass reaction vessel equipped with a Liebig condenser, a stirrer with Teflon® impellers and a stirring seal, a nitrogen inlet tube, and a temperature sensor. The mixture was heated to 70°C while stirring at 250 rpm and introducing nitrogen at a rate of 200 mL / min. Next, a mixed solution of 133.4 parts methoxypolyethylene glycol monomethacrylate (average number of ethylene oxide moles added: 9), 26.6 parts methacrylic acid, 1.53 parts mercaptopropionic acid, and 106.7 parts deionized water was added dropwise over 4 hours. Simultaneously, a mixed solution of 1.19 parts ammonium persulfate and 50.6 parts deionized water was added dropwise over 5 hours. After the dropwise addition was complete, the mixture was maintained at 70°C for 1 hour to complete the polymerization reaction. Finally, the mixture was neutralized with an aqueous sodium hydroxide solution to obtain an aqueous solution of cement dispersant 1 with a weight-average molecular weight of 100,000.

[0041] <Example 1> 453 parts of deionized water and 64 parts of a 20% aqueous solution of emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Hytenol LA-10) were charged into a flask equipped with a dropping funnel, stirrer, nitrogen gas inlet tube, thermometer, and reflux condenser. A pre-emulsion was prepared in the dropping funnel consisting of 30 parts of deionized water, 32 parts of a 20% aqueous solution of emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Hytenol LA-10), 322 parts of ethyl acrylate, 234 parts of methacrylic acid, and 832 parts of a 10% aqueous solution of methyl polyethylene glycol (90) monomethacrylate (manufactured by NOF Corporation, product name: Bremmer PME-4000). 73 parts of this pre-emulsion was added to the flask, and the temperature was raised to 72°C while slowly blowing in nitrogen gas. Polymerization was initiated by adding 2.3 parts of a 5.0% aqueous solution of sodium bisulfite and 8 parts of a 1.0% aqueous solution of ammonium persulfate to the flask. Next, the remaining pre-emulsion for dropwise addition and 144 parts of a 1.0% aqueous solution of ammonium persulfate were uniformly added dropwise to the flask over a period of 120 minutes. After the addition was complete, the contents of the flask were maintained at 72°C for 60 minutes and then cooled to complete the polymerization reaction. After the resulting reaction solution was cooled to room temperature, it was filtered through a 300-mesh (JIS mesh, the same applies hereafter) wire mesh to obtain an emulsion with a non-volatile content of 29.6% by mass. The emulsion particles contained in this resin emulsion had an average particle size of 136 nm, and the glass transition temperature of the entire emulsion was 14°C.

[0042] <Examples 2-12> Emulsions for Examples 2 to 12 were obtained in the same manner as in Example 1, except that the monomer components (ethyl acrylate, methacrylic acid, methyl polyethylene glycol (90) monomethacrylate) and their composition ratios used in Example 1 were changed to the monomer components (a, b, c) and their composition ratios (mass ratio) (a:b:c) shown in Tables 1 and 2 below. The detailed properties of these resin emulsions are shown in Tables 1 and 2 below.

[0043] The details of the methods for evaluating the properties of polymers and emulsions prepared in this specification are described below.

[0044] <Particle size> In this specification, the average particle diameter of emulsion particles refers to the volume-average particle diameter measured using a dynamic light scattering particle size distribution analyzer [Particle Sizing Systems, Inc., product name: NICOMP Model 380]. <Solid content (non-volatile content)> The solid content of the emulsion is determined by weighing 1 g of emulsion, drying it in a hot air dryer at 110°C for 1 hour, and considering the resulting residue as non-volatile content. The value is calculated using the formula: Non-volatile content of emulsion (mass%) = ([mass of residue] ÷ [1 g of emulsion]) × 100 (%).

[0045] <Molecular weight> Weight-average molecular weight is obtained by gel permeation chromatography (GPC). Measurements were taken using a system manufactured by Tosoh Corporation, part number: HLC-8120GPC, with columns: TSKgel G-5000HXL and TSKgel GMHXL-L used in series. (Polystyrene equivalent) <ph> pH was measured at 25°C using a pH meter (LAQUA, manufactured by Horiba, Ltd.) in accordance with JIS Z 8802.

[0046] <tg> In this specification, the glass transition temperature of a resin is expressed using the glass transition temperature of the monomer homopolymer used in the monomer components constituting the resin, using the formula: 1 / Tg = Σ(Wm / Tgm) / 100 [In the formula, Wm represents the content (mass%) of monomer m in the monomer components constituting the resin, and Tgm represents the glass transition temperature (absolute temperature: K) of the monomer m homopolymer.] This refers to the temperature determined based on Fox's formula, which is expressed as follows: In this specification, unless otherwise specified, the glass transition temperature of the resin constituting the emulsion particles refers to the glass transition temperature determined based on Fox. The glass transition temperature of the entire emulsion particle having multiple resin layers refers to the glass transition temperature determined based on Fox's formula, using the glass transition temperatures of the monomer homopolymers used in all monomer components used as raw materials for all resin layers used in multi-stage emulsion polymerization. For monomers whose glass transition temperature is unknown, such as special monomers and polyfunctional monomers, if the total amount of monomers with unknown glass transition temperatures in the monomer component is 10% by mass or less, the glass transition temperature can be determined using only monomers with known glass transition temperatures. If the total amount of monomers with unknown glass transition temperatures in the monomer component exceeds 10% by mass, the glass transition temperature of the resin can be determined by differential scanning calorimetry (DSC), differential calorimetry (DTA), thermomechanical analysis (TMA), etc. The glass transition temperatures of resins are, for example, 105°C for methyl methacrylate homopolymer, -70°C for 2-ethylhexyl acrylate homopolymer, -56°C for n-butyl acrylate homopolymer, 83°C for cyclohexyl methacrylate homopolymer, 107°C for tert-butyl methacrylate homopolymer, 55°C for 2-hydroxyethyl methacrylate homopolymer, 95°C for acrylic acid homopolymer, 130°C for methacrylic acid homopolymer, and 100°C for styrene homopolymer.

[0047] <Acid value> The acid value (mgKOH / g) per gram of resin solids was measured according to JIS K0070:1992 using an automatic titrator (product name: COM-555, manufactured by Hiranuma Sangyo Co., Ltd.).

[0048] The product names or abbreviations listed in Tables 1 to 3 mean the following: MAA: Methacrylic acid EA: Ethyl acrylate MA: Methyl acrylate EO: Ethylene oxide (ethylene glycol) PO: Propylene oxide (propylene glycol) BO: Butylene oxide (butylene glycol) Bremmer (registered trademark) PME-4000: Methoxypolyethylene glycol (90) monomethacrylate Bremmer (registered trademark) PSE-1300: Stearoxy polyethylene glycol (30) monomethacrylate Bremmer (registered trademark) PP-800: Polypropylene glycol (13) monomethacrylate Bremmer® PE-350: Polyethylene glycol (8) monomethacrylate Bremmer (registered trademark) 10PPB-500B: Propylene glycol, polybutylene glycol (6) monomethacrylate Hythenol LA-10: Polyoxyethylene alkyl ether ammonium sulfate Adekarya Soap SR-20: Ether sulfate type ammonium salt IPN-50: A compound obtained by adding ethylene oxide to the hydroxyl group of 3-methyl-3-buten-1-ol (isoprennol) at an average addition mole number of 50.

[0049] [Table 1]

[0050] [Table 2]

[0051] <Example 13> In a 2.5 L stainless steel reaction vessel equipped with a PAA reflux condenser and a stirrer, 1358.8 g of deionized water was charged and heated to its boiling point under stirring. Then, under stirring, 523.5 g (i.e., 5.82 moles) of 80% by weight acrylic acid aqueous solution (hereinafter referred to as "80% AA") was added dropwise for 75 minutes, 7.8 g of 15% by weight sodium persulfate aqueous solution (hereinafter referred to as "15% NaPS") was added dropwise for 140 minutes, and 109.9 g of deionized water was added dropwise for 140 minutes, each through separate supply channels and nozzles. The addition of each component was carried out continuously at a constant dropping rate. After the addition of 80% AA was completed, the reaction solution was held at its boiling point (aged) for another 65 minutes to complete the polymerization and obtain an aqueous solution of a (meth)acrylic acid polymer. The weight-average molecular weight (Mw) of the aqueous solution was 450,000, and the number-average molecular weight (Mn) was 73,000.

[0052] <Example 14> 1460 g of a 37% sodium acrylate aqueous solution was placed in a 2000 ml stainless steel container. Dissolved oxygen was removed from this sodium acrylate aqueous solution by nitrogen bubbling. Next, the temperature of this aqueous solution was adjusted to 20°C, and then 20 g of a 0.289% aqueous solution of V-50 (manufactured by Wako Pure Chemical Industries, Ltd., an azo-based photopolymerization initiator, chemical name: 2,2′-azobis-2-amidinopropane dihydrochloride), a photopolymerization initiator, and 20 g of a 0.862% aqueous solution of sodium hypophosphite, a chain transfer agent, were added and mixed uniformly. The monomer (sodium acrylate) concentration in the reaction solution was 36% by mass. The amount of V-50 added was 0.01 g per mole of monomer. The amount of sodium hypophosphite added was 0.03 g per mole of monomer. The weight-average molecular weight (Mw) of the polyacrylic acid completely neutralized polymer was 640,000, and the number-average molecular weight (Mn) was 112,000. Furthermore, the variance (Mw / Mn) was 5.7.

[0053] <Example 15> 240 g of acrylic acid, 918 g of 37% sodium acrylate aqueous solution, and 282 g of deionized water were placed in a 2000 ml stainless steel container to obtain an aqueous solution of partially neutralized acrylic acid salt. Dissolved oxygen was removed from this aqueous solution by nitrogen bubbling. Next, the temperature of this aqueous solution was adjusted to 20°C, and then 20 g of a 0.36% acrylic acid solution of Darocure 1173 (manufactured by Ciba Specialty Chemicals, chemical name: 2-hydroxy-2-methyl-1-phenyl-propan-1-one), a photopolymerization initiator, and 20 g of a 0.36% sodium hypophosphite aqueous solution, a chain transfer agent, were added and homogeneously mixed to obtain a reaction solution. This reaction solution contained acrylic acid and sodium acrylate as monomers, and the proportion of the salt-type monomer (sodium acrylate) in the total monomers, i.e., the degree of neutralization, was 50 mol%. The monomer concentration (acrylic acid and sodium acrylate) in this reaction solution was 40% by mass. The amount of Darocure 1173 added was 0.01 g per mole of monomer. The amount of sodium hypophosphite added was also 0.01 g per mole of monomer. The weight-average molecular weight (Mw) of the polymer salt was 2.53 million, and the number-average molecular weight (Mn) was 44,000. The degree of dispersion (Mw / Mn) was 57.5.

[0054] Table 3 below shows the composition (molar ratio) of the monomer components used in the polymers of Examples 13 to 15 and the properties of the copolymers (salts). AA: Acrylic acid SA: Sodium acrylate

[0055] [Table 3]

[0056] <Concrete mixing methods and granulation tests> The cement used was ordinary Portland cement (manufactured by Taiheiyo Cement Corporation), the fine aggregate was land sand from the Oigawa River system, the coarse aggregate was crushed stone from Aomi, and the mixing water was tap water. Cement: 382 kg / m³ 3 , Water: 172kg / m 3 , Fine aggregate: 796kg / m 3 , Coarse aggregate: 930kg / m 3 Fresh concrete was prepared using a mix design with a fine aggregate ratio (fine aggregate / fine aggregate + coarse aggregate) (volume ratio) of 47% and a water / cement ratio (mass ratio) of 0.45. The mixing for the above adjustments was carried out using a forced mixer for a mixing time of 90 seconds under conditions of room temperature 20±3℃ and humidity 60±5%. In addition, the flow value and air content of the fresh concrete were measured in accordance with Japanese Industrial Standards (JIS A-1101, 1128:2014), and cement dispersant 1 was added so that the slump flow value was 400 mm ± 20 mm.

[0057] Furthermore, to ensure that the temperature of the fresh concrete reached the measurement temperature of 20°C, the materials used for measurement, the forced-mix mixer, and the measuring instruments were all temperature-controlled under the aforementioned measurement temperature atmosphere. Mixing and each measurement were performed under the aforementioned measurement temperature atmosphere. In addition, to avoid the influence of air bubbles in the fresh concrete on the fluidity of the cement composition, an oxyalkylene-based defoamer was used as needed to adjust the air content to 4.5 ± 0.5%.

[0058] After measuring the flow rate and air volume, the mixture was left to stand for 30 minutes. Then, the fresh concrete was placed in a 70L tiltable mixer (manufactured by KYC Corporation), and one of the solutions prepared in Examples 1 to 15 was added. The mixture was then stirred for 5 minutes at a rotation speed of 20 rpm. After the granular material was discharged from the mixer, it was left to stand for 1 hour to cure. After this curing period, each of the granular materials from Examples 1 to 15 was classified (sieved) using a JIS sieve with a mesh size of approximately 4 mm and a JIS sieve with a mesh size of approximately 10 mm. Furthermore, the amount of the solutions (emulsions) from Examples 1 to 12 relative to the fresh concrete in the mixer mentioned above is 0.5 kg / m³. 3 The amount added was such that in Examples 13-15 it was 4.0 kg / m 3 The amount added was as follows. The results of the above sieving are shown in Tables 4 to 6 below (in these tables, the unit for values ​​shown only is mass%).

[0059] [Table 4]

[0060] [Table 5]

[0061] [Table 6]

[0062] The results in Tables 4 and 5 show that Examples 1 to 12 according to the present invention (including structural units having one carboxyl group) exhibit excellent performance in granulating fresh concrete. Furthermore, in Examples 1 to 10, which include structural units having polyalkylene glycol groups (hydroxyl-terminated) or alkoxy polyalkylene glycol groups (alkyl-terminated), a tendency for smaller granular size was observed compared to Examples 11 and 12. Moreover, it was confirmed that Examples 1 to 12, which are emulsions, showed similar granulation results to Examples 13 to 15, which are not emulsions, despite having a smaller additive amount.

[0063] The results in Table 6 show that Examples 13-15 according to the present invention (including structural units having one carboxyl group and / or those in which the carboxyl group is neutralized) exhibit excellent performance in granulating fresh concrete. Furthermore, Examples 14 and 15, which included structural units with neutralized carboxyl groups, showed a tendency for smaller granular size compared to Example 13.< / tg> < / ph>

Claims

1. (i) a polymer that exhibits an acidic pH when prepared as an aqueous solution or aqueous dispersion, or (ii) a salt of the polymer, It contains, The polymer is an O / W (oil-in-water) emulsion containing 20.0 to 60.0% by mass of a structural unit (I) having an acidic functional group, and has the following formula (II): 【Chemistry 1】 (In formula (II), R 5 to R 8 are the same or different, and represent a hydrogen atom, an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, or -COOM 1 (where M 1 is a monovalent hydrocarbon group having 1 to 8 carbon atoms).) The polymer contains 30.0 to 70.0% by mass of the hydrophobic structural unit (II) represented by (II) based on the total mass of the polymer. A granulating agent for fresh concrete, wherein the weight-average molecular weight of the polymer is 50,000 to 5,000,000.

2. The granulating agent for fresh concrete according to claim 1, wherein the polymer contains structural units having carboxyl groups.

3. The above polymer can be further expressed by the following formula (III): 【Chemistry 2】 (In equation (III), X is C = O or (CH ２ )p [where p is an integer from 0 to 5]. R １２ R is a hydrocarbon group having 2 to 8 carbon atoms. m is an integer from 5 to 300. １３ R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 8 carbon atoms. ９ ~R １１ The granulating agent for fresh concrete according to claim 1, wherein the hydrophobic structural unit (III) represented by ( ) is the same or different, a hydrogen atom, or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, is contained in an amount of 1.0 to 40.0% by mass relative to the total mass of the polymer.

4. A granulating agent for fresh concrete according to claim 1, comprising a polymer that exhibits an acidic pH when prepared as an aqueous solution or aqueous dispersion, wherein the polymer exhibits a pH of 2.0 to 5.0 when prepared as a 10.0% by mass aqueous solution or aqueous dispersion at 25.0°C.

5. The granulating agent for fresh concrete according to claim 1, comprising a polymer that exhibits an acidic pH when prepared as an aqueous solution or aqueous dispersion, wherein the polymer is emulsified with water as the dispersion medium.

6. The granulating agent for fresh concrete according to claim 1, wherein the glass transition temperature of the polymer is between -40°C and 80°C.

7. The granulating agent for fresh concrete according to claim 1, wherein the acid value of the polymer is 50 mg KOH / g or more and 500 mg KOH / g or less.

8. A granulating agent for fresh concrete according to claim 1, which does not contain a rapid setting accelerator.

9. A method for forming granules, comprising the step of adding a granulating agent according to any one of claims 1 to 8 to fresh concrete, stirring it, and then curing the mixture.

10. A granular material containing the granulating agent and cement according to any one of claims 1 to 8.

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