Dispersant for hydraulic composition

Abstract

To provide a dispersant for a polycarboxylic acid based hydraulic composition, imparting excellent shape retention to a hydraulic composition.SOLUTION: There is provided a dispersant for a hydraulic composition, containing a component (A) which is a polycarboxylic acid based specific copolymer and a component (B) which is a polyacrylic acid in which a part of hydrogen of a carboxy group may be substituted with a counter cation, in which the content of the component (B) relative to the content of the component (A) is 0.1 mass% or more and 5 mass% or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a dispersant for a hydraulic composition, and further to a hydraulic composition containing the dispersant and a method for producing the same. [Background technology]

[0002] Dispersants such as naphthalene-based, melamine-based, aminosulfonic acid-based, and polycarboxylic acid-based dispersants are used to impart fluidity and shape retention to hydraulic compositions such as mortar and concrete. In particular, with regard to shape retention, dispersants for hydraulic compositions with further enhanced fluidity are increasingly being used to improve workability.

[0003] As such a dispersant, for example, Patent Document 1 discloses a dispersant having a component A: a structural unit formed from acrylic acid and / or a salt thereof, and having a mass average molecular weight M A component B: a polymer having a structural unit of acrylic acid and / or a salt thereof, and having a mass average molecular weight M B An additive for hydraulic compositions containing a polymer having a molecular weight of 100,000 or more and 50,000,000 or less is disclosed.

[0004] Patent Document 2 discloses a method for improving the fluidity retention of a hydraulic composition by adding at least one polycarboxylic acid dispersant (1) made of a polymer having a carboxylic acid monomer ratio of more than 30% by weight and at least one polycarboxylic acid dispersant (2) made of a polymer having a carboxylic acid monomer ratio of 30% by weight or less to a hydraulic slurry containing water having a sulfate ion concentration of 2,500 mg / kg or more and 40,000 mg / kg or less in the aqueous solution portion and hydraulic powder.

[0005] Furthermore, Patent Document 3 discloses a concrete admixture comprising essentially: (i) component: a copolymer obtained by polymerizing (A) an ester of an unsaturated monocarboxylic acid and a polyalkyleneoxyglycol with (b) one or more monomers selected from compounds represented by (B) (meth)acrylic acid or a salt thereof, and (C) α,β-unsaturated alkylsulfonic acid or a salt thereof; and (ii) component: a water-soluble salt of a homopolymer or a copolymer of two or more kinds of unsaturated carboxylic acids selected from unsaturated monocarboxylic acids and unsaturated dicarboxylic acids. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 115790 [Patent Document 2] JP 2003-335566 A [Patent Document 3] Japanese Patent Application Publication No. 9-67153 Summary of the Invention [Problem to be solved by the invention]

[0007] On the other hand, by exhibiting a suitable fluidity with the passage of time after kneading, excellent operability and high productivity are imparted until the hydraulic composition is filled. However, after filling, it is desired to reduce the fluidity of the hydraulic composition, that is, to express shape retention, in order to facilitate work such as troweling. There is a demand for the development and further improvement of polycarboxylic acid-based hydraulic composition dispersants that impart such excellent shape retention to hydraulic compositions. [Means for solving the problem]

[0008] The present invention relates to a dispersant composition for hydraulic compositions, which contains the following component (A) and the following component (B), in which the content of the component (B) relative to the content of the component (A) is 0.1 mass % or more and 5 mass % or less.

[0009] <Component (A)> A copolymer having a structural unit (A1) represented by the following formula (A1) and a structural unit (A2) represented by the following formula (A2), in which the proportion of the structural unit (A1) relative to the total of all structural units of component (A), which is the sum of the structural units (A1) and (A2), is 11% by mass or more and less than 25% by mass.

[0010] [ka]

[0011] [In the formula, R 1a represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 1a represents a hydrogen atom or a counter cation.

[0012] [ka]

[0013] [In the formula, R 2a R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 3a represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. a represents an alkylene group or a carbonyl group having 0 to 4 carbon atoms; AO represents an oxyalkylene group having 2 to 4 carbon atoms; and na represents the average number of moles of AO added, which is a number of 5 to 150.

[0014] <(B) component> A polyacrylic acid in which the hydrogen atom of the carboxy group may be substituted with a counter cation.

[0015] The present invention also relates to a hydraulic composition comprising hydraulic powder, aggregate, water, the component (A) and the component (B), wherein the content of the component (B) relative to the content of the component (A) is 0.1 mass % or more and 5 mass % or less.

[0016] Furthermore, the present invention relates to a method for producing a hydraulic composition, which comprises mixing hydraulic powder, aggregate, water, the component (A), and the component (B), and the amount of the component (B) mixed relative to the amount of the component (A) mixed is 0.1 mass % or more and 5 mass % or less. Effect of the Invention

[0017] According to the present invention, there is provided a polycarboxylic acid-based hydraulic composition dispersant that imparts excellent shape retention to the hydraulic composition. Also, according to the present invention, there are provided a hydraulic composition exhibiting excellent shape retention and a method for producing the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] <Additive for clay-containing hydraulic compositions> The dispersant for hydraulic compositions of the present invention contains the components (A) and (B) in a given ratio.

[0019] Component (A) is a copolymer having a structural unit (A1) represented by formula (A1) below and a structural unit (A2) represented by formula (A2) below, in which the proportion of structural unit (A1) relative to the total of all structural units of component (A), which is the sum of structural units (A1) and (A2), is at least 11% by mass and less than 25% by mass.

[0020] [ka]

[0021] [In the formula, R 1a represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 1a represents a hydrogen atom or a counter cation.

[0022] [ka]

[0023] [In the formula, R 2aR represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 3a represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. a represents an alkylene group or a carbonyl group having 0 to 4 carbon atoms; AO represents an oxyalkylene group having 2 to 4 carbon atoms; and na represents the average number of moles of AO added, which is a number of 5 to 150.

[0024] In formula (A1), M 1a represents one or more selected from a hydrogen atom and a counter cation. Examples of the counter cation include alkali metals such as sodium and potassium; alkaline earth metals such as magnesium; ammonium; mono-, di-, tri-, or tetra-(mono-, di-, or trialkyl having 2 to 8 carbon atoms, which may be substituted with a hydroxyl group); and the like. From the viewpoints of convenience and easy availability, the counter cation is preferably an alkali metal, and more preferably sodium.

[0025] M of the monomer used to introduce the structural unit (A1) 1a A counter cation can be introduced by copolymerizing the carboxyl group using a hydrogen atom as a raw material, and then neutralizing the carboxyl group with an alkali metal or alkaline earth metal hydroxide, ammonia, or a mono-, di-, or tri-(alkyl having 2 to 8 carbon atoms, which may be substituted with a hydroxyl group)amine. Alternatively, a hydrogen atom of the carboxyl group can be exchanged for an ammonium ion using a halide or hydroxide of (mono-, di-, or tri-alkyl having 2 to 8 carbon atoms, which may be substituted with a hydroxyl group). Alternatively, a monomer having a counter cation can be used for copolymerization. From the viewpoint of convenience, it is preferable to introduce the counter cation after copolymerization.

[0026] From the viewpoint of good shape retention, it is preferable that 20 to 95% of the hydrogen atoms of the carboxy groups are substituted with counter cations.

[0027] From the viewpoint of good shape retention, R in formula (A1) 1a is preferably a hydrogen atom or a methyl group.

[0028] From the viewpoint of good shape retention, R in formula (A2) 2a is preferably a hydrogen atom or a methyl group, more preferably a methyl group. 3a is preferably a hydrogen atom or a methyl group, more preferably a methyl group.

[0029] From the viewpoint of good shape retention, X in formula (A2) a is an alkylene group having 0 to 4 carbon atoms, X a is preferably a methylene group. In addition, AO in formula (A2) is an oxyalkylene group having 2 to 4 carbon atoms, and more preferably contains an oxyethylene group. In addition, na in formula (A2) is 5 or more, preferably 10 or more, and 150 or less, preferably 100 or less, and more preferably 80 or less. In addition, AO may be different in an average of na repeating units, and may include random addition, block addition, or a mixture of these. AO is preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more of oxyethylene groups, and further preferably all AO groups are ethyleneoxy groups. For example, AO may also contain oxypropylene, oxybutylene, etc. in addition to oxyethylene.

[0030] The structural unit (A2) can be obtained, for example, by using the corresponding monomers shown below. (1)X a When is an alkylene group: ethers of vinyl alcohol, allyl alcohol, methallyl alcohol, 3-buten-1-ol, 3-methyl-3-buten-1-ol (isoprenol), 4-penten-1-ol, 5-hexen-1-ol and polyethylene glycol or alkoxypolyethylene glycol capped at one end with an alkyl group. (2)X a When is a carbonyl group: a monoester of polyethylene glycol and acrylic acid or methacrylic acid, or an ester of alkoxypolyethylene glycol capped at one end with an alkyl group and acrylic acid or methacrylic acid.

[0031] In the present application, the sum of the structural units (A1) and (A2), which are structural units of the component (A), is referred to as "all structural units of the component (A)".

[0032] From the viewpoint of good shape retention, the proportion of the structural unit (A1) to all structural units of the component (A) is preferably 11% by mass or more, more preferably 12% by mass or more, and preferably less than 25% by mass, more preferably 22% by mass or less, more preferably 20% by mass or less, and even more preferably 16% by mass or less. This proportion is calculated by ([mass of structural unit (A1)] / [mass of all structural units of the component (A)])×100.

[0033] From the viewpoint of good shape retention, the copolymer of component (A) preferably has a molar ratio of the structural unit (A1) to all structural units of component (A) of 65 mol% or more, more preferably 70 mol% or more, even more preferably 75 mol% or more, and preferably 98 mol% or less, more preferably 95 mol% or less, even more preferably 90 mol% or less. This ratio is calculated by ([moles of structural unit (A1)] / [moles of all structural units of component (A)])×100.

[0034] The copolymer of component (A) may have a structural unit other than the structural units (A1) and (A2) [hereinafter, also referred to as structural unit (A')]. Examples of the structural unit (A') include 2-(methacryloyloxy)ethyl phosphate, 2-hydroxyethyl acrylate, methyl acrylate, methyl methacrylate, and 2-hydroxyethyl methacrylate.

[0035] When the structural unit (A') is used, from the viewpoint of good shape retention, the total proportion of all structural units of component (A), including structural unit (A'), in component (A) is preferably 80 mass% or more, more preferably 90 mass% or more, more preferably 93 mass% or more, even more preferably 95 mass% or more, and preferably 100 mass% or less.

[0036] From the viewpoint of good shape retention, the weight average molecular weight of the copolymer of component (A) is preferably 1,000 or more, more preferably 10,000 or more, and preferably 100,000 or less, more preferably 80,000 or less. This weight average molecular weight was measured using a high-speed GPC (HLC-8320GPC, manufactured by Tosoh Corporation), detector: RI, column: G4000PWXL+G2500PWXL (anion), mobile phase: 0.2 M phosphate buffer / acetonitrile=9 / 1, flow rate: 1.0 mL / min, column temperature: 40° C., and standard substance: polyethylene glycol.

[0037] The component (B) is a polyacrylic acid that has acrylic acid as a structural unit, in which the hydrogen atom of the carboxy group may be substituted with a counter cation.

[0038] Examples of the counter cation substituting the hydrogen atom of the carboxy group include alkali metals such as sodium and potassium, alkaline earth metals such as magnesium, ammonium, mono-, di-, tri- or tetra-(mono-, di- or trialkyl having 2 to 8 carbon atoms, which may be substituted with a hydroxyl group), etc. From the viewpoints of convenience and availability, alkali metals are preferred as the counter cation, and sodium is more preferred.

[0039] The substitution of hydrogen atoms of the carboxyl group with these counter cations can be carried out by obtaining polyacrylic acid by polymerization using acrylic acid, and then neutralizing the carboxyl group with a hydroxide of an alkali metal or alkaline earth metal, ammonia, or a mono-, di-, or tri-(alkyl having 2 to 8 carbon atoms, which may be substituted with a hydroxyl group). Alternatively, the proton of the carboxyl group can be exchanged for an ammonium ion using a halide or hydroxide of (mono-, di-, or tri-alkyl having 2 to 8 carbon atoms, which may be substituted with a hydroxyl group). Alternatively, polyacrylic acid in which some of the hydrogen atoms of the carboxyl group are substituted with counter cations can be obtained by polymerization using acrylic acid and an acrylic acid salt. From the viewpoint of convenience, it is preferable to perform the substitution with counter cations after obtaining polyacrylic acid.

[0040] From the viewpoint of good shape retention, it is preferable that 20 to 90% of the hydrogen atoms of the carboxyl groups are substituted with counter cations, and 0% is more preferable.

[0041] The component (B) is a polyacrylic acid in which hydrogen atoms may be substituted with counter cations, and may contain, as the structural unit (hereinafter also referred to as structural unit (B')), for example, 2-(methacryloyloxy)ethyl phosphate, 2-hydroxyethyl acrylate, methyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, methacrylic acid, etc.

[0042] From the viewpoint of good shape retention, the proportion of acrylic acid in all structural units of component (B) is preferably 80% by mass or more, more preferably 90% by mass or more, more preferably 93% by mass or more, even more preferably 95% by mass or more, and preferably 100% by mass or less.

[0043] From the viewpoint of good shape retention, the weight average molecular weight of the (B) component is 1,000 or more, preferably 1,500 or more, and 40,000 or less, more preferably 35,000 or less, and further preferably 30,000 or less. This weight average molecular weight can be measured in the same manner as the (A) component.

[0044] The ratio of the content of the (B) component to the content of the (A) component in the dispersant for hydraulic compositions of the present invention is 0.1 mass% or more, preferably 0.5 mass% or more, and 5 mass% or less, preferably 3 mass% or less, from the viewpoint of good shape retention. This ratio is calculated by ([content (mass) of the (B) component)] / [content (mass) of the (A) component)])×100.

[0045] The dispersant for hydraulic compositions of the present invention may contain, as optional components, components such as retarders, hardening accelerators, AE agents, expanding agents, foaming agents, thickeners, fluidizing agents, foaming agents, waterproofing agents, and defoamers (excluding those corresponding to components (A) and (B)).

[0046] The dispersant for hydraulic compositions of the present invention may contain water. The dispersant for hydraulic compositions of the present invention may be a liquid.

[0047] <Hydraulic composition> The present invention provides a hydraulic composition comprising hydraulic powder, aggregate, water, the component (A) and the component (B), wherein the ratio of the content of the component (B) to the content of the component (A) is 0.1 mass % or more and 5 mass % or less.

[0048] The matters described in the hydraulic composition dispersant of the present invention can be appropriately applied to the hydraulic composition of the present invention. For example, specific examples and preferred aspects of the (A) and (B) components in the hydraulic composition dispersant of the present invention are the same as those in the hydraulic composition dispersant. In addition, the preferred range of the ratio of the content of the (B) component to the content of the (A) component in the hydraulic composition of the present invention is also the same as that in the hydraulic composition dispersant of the present invention.

[0049] The ratio of the content of the (B) component to the content of the (A) component in the dispersant for hydraulic compositions of the present invention is 0.1 mass% or more, preferably 0.5 mass% or more, and 5 mass% or less, preferably 3 mass% or less, from the viewpoint of good shape retention. This ratio is calculated by ([content (mass) of the (B) component)] / [content (mass) of the (A) component)])×100.

[0050] The hydraulic powder is a powder having a physical property of being hardened by a hydration reaction, and examples thereof include cement and gypsum. Preferred are ordinary portland cement, belite cement, moderate heat cement, early strength cement, ultra-early strength cement, and sulfate-resistant cement. In addition, powders having pozzolanic action and / or latent hydraulic properties, such as blast furnace slag, fly ash, and silica fume, and powders having stone powder (calcium carbonate powder) or the like may be added to these, such as blast furnace slag cement, fly ash cement, and silica fume cement. Here, when the hydraulic powder includes powders selected from powders having pozzolanic action, powders having latent hydraulic properties, and stone powder (calcium carbonate powder) in addition to powders having physical properties of being hardened by a hydration reaction, such as cement, the amount of these powders is also included in the amount of the hydraulic powder in the present invention. In addition, when the powder having physical properties of being hardened by a hydration reaction contains a high-strength admixture, the amount of the high-strength admixture is also included in the amount of the hydraulic powder. The same applies to parts by mass and mass ratios that involve the mass of the hydraulic powder.

[0051] Examples of the aggregate include aggregates selected from fine aggregates and coarse aggregates. Examples of the fine aggregate include those specified by number 2311 in JIS A0203-2014. Examples of the fine aggregate include river sand, land sand, mountain sand, sea sand, lime sand, silica sand and crushed sands thereof, blast furnace slag fine aggregate, ferronickel slag fine aggregate, lightweight fine aggregate (artificial and natural), and recycled fine aggregate. Examples of the coarse aggregate include those specified by number 2312 in JIS A0203-2014. For example, examples of the coarse aggregate include river gravel, land gravel, mountain gravel, sea gravel, lime gravel, crushed stones thereof, blast furnace slag coarse aggregate, ferronickel slag coarse aggregate, lightweight coarse aggregate (artificial and natural), and recycled coarse aggregate. Different types of fine aggregates and coarse aggregates may be mixed and used, or a single type may be used.

[0052] From the viewpoint of good shape retention, the hydraulic composition of the present invention contains, relative to 100 parts by mass of hydraulic powder, preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, even more preferably 0.1 part by mass or more of component (A), and preferably 0.5 part by mass or less, more preferably 0.4 part by mass or less, and even more preferably 0.3 part by mass or less.

[0053] From the viewpoint of good shape retention, the hydraulic composition of the present invention contains, relative to 100 parts by mass of the hydraulic powder, preferably 0.0005 parts by mass or more, more preferably 0.001 parts by mass or more, even more preferably 0.0015 parts by mass or more of the (B) component, and preferably 0.03 parts by mass or less, more preferably 0.02 parts by mass or less, and even more preferably 0.015 parts by mass or less.

[0054] The water / hydraulic powder ratio of the hydraulic composition of the present invention [the mass percentage (mass%) of water and hydraulic powder in the composition, abbreviated as W / C when the hydraulic powder is cement] is preferably 15% or more, more preferably 25% or more, and preferably 60% or less, more preferably 40% or less, from the viewpoints of strength development and workability.

[0055] When the hydraulic composition is concrete, the amount of coarse aggregate used is preferably 50% or more, more preferably 55% or more, even more preferably 60% or more, and preferably 100% or less, more preferably 90% or less, even more preferably 80% or less, from the viewpoints of expressing the strength of the hydraulic composition, reducing the amount of hydraulic powder such as cement used, and improving the filling property into a formwork, etc. 3 It is the ratio of the volume of coarse aggregate (including voids) in the concrete. When the hydraulic composition is a mortar, the amount of fine aggregate used is preferably 800 kg / m 3 More preferably, 900kg / m 3 More preferably, 1,000 kg / m 3 and preferably 2,000 kg / m 3 Less than or equal to 1,800 kg / m 3 or less, more preferably 1,700 kg / m3 The following is the result.

[0056] The hydraulic composition of the present invention may contain, as optional components, components such as retarders, hardening accelerators, AE agents, expanding agents, foaming agents, thickeners, fluidizing agents, foaming agents, waterproofing agents, defoamers, and preservatives (excluding those corresponding to components (A) and (B)).

[0057] The hydraulic composition of the present invention can be cured by a known method to obtain a cured product. The curing of the hydraulic composition can be carried out taking into consideration the application, shape, etc. of the cured product.

[0058] <Method for producing hydraulic composition> The present invention relates to a method for producing a hydraulic composition, which comprises mixing a hydraulic powder, an aggregate, water, the component (A) and the component (B), The ratio of the amount of the (B) component mixed to the amount of the (A) component mixed is 0.1% by mass or more and 5% by mass or less. A method for producing a hydraulic composition is provided.

[0059] The items described in the hydraulic composition dispersant and hydraulic composition of the present invention can be appropriately applied to the method for producing the hydraulic composition of the present invention. Specific examples and preferred aspects of the hydraulic powder, aggregate, component (A), component (B), and optional components used in the method for producing the hydraulic composition of the present invention are the same as those of the hydraulic composition dispersant and hydraulic composition of the present invention. In addition, the content of each component in the hydraulic composition dispersant and hydraulic composition of the present invention can be replaced with the mixed amount, and the preferred range can be applied to the method for producing the hydraulic composition of the present invention.

[0060] In the method for producing a hydraulic composition of the present invention, the ratio of the amount of component (B) mixed to the amount of component (A) mixed is 0.1% by mass or more, preferably 0.5% by mass or more, and 5% by mass or less, preferably 3% by mass or less, from the viewpoint of good shape retention. This ratio is calculated by ([amount (mass) of component (B) mixed] / [amount (mass) of component (A) mixed])×100.

[0061] The method for producing the hydraulic composition of the present invention is not limited to the order of mixing the components, but an example of a method for more easily obtaining a high effect is to mix the hydraulic powder with the aggregate, and then mix the kneading liquid containing the (A) and (B) components and water. For example, the hydraulic powder, the coarse aggregate and the fine aggregate are mixed for a predetermined time, for example, from 5 to 60 seconds, and then the kneading liquid containing the (A) and (B) components and water is mixed. The mixing can be performed with a known mixer. The kneading liquid may be an aqueous solution or an aqueous suspension.

[0062] In the method for producing the hydraulic composition of the present invention, the components (A) and (B) can be mixed with the hydraulic powder so that they each fall within the ranges described for the hydraulic composition of the present invention. That is, in the method for producing the hydraulic composition of the present invention, from the viewpoint of good shape retention, the (A) component is mixed in an amount of preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, even more preferably 0.1 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.4 part by mass or less, and even more preferably 0.3 part by mass or less, per 100 parts by mass of the hydraulic powder. In the method for producing the hydraulic composition of the present invention, from the viewpoint of good shape retention, the (B) component is mixed in an amount of preferably 0.0005 parts by mass or more, more preferably 0.001 parts by mass or more, even more preferably 0.0015 parts by mass or more, and preferably 0.03 parts by mass or less, more preferably 0.02 parts by mass or less, and even more preferably 0.015 parts by mass or less, relative to 100 parts by mass of the hydraulic powder.

[0063] In the method for producing the hydraulic composition of the present invention, optional components such as retarders, hardening accelerators, AE agents, expansion agents, foaming agents, thickeners, fluidizing agents, foaming agents, waterproofing agents, defoamers, and preservatives (excluding those corresponding to the components (A) and (B)) can be mixed.

[0064] In addition, in the method for producing the hydraulic composition of the present invention, from the viewpoint of workability, water and hydraulic powder are mixed so that the water / hydraulic powder ratio (mass%) is preferably 15% or more, more preferably 25% or more, and preferably 60% or less, more preferably 40% or less. EXAMPLES

[0065] The following monomers were used as raw materials for producing the copolymer of component (A). (A1) Component: methacrylic acid (MAA) and acrylic acid (AA). As the component (A2), (i) Ester of methacrylic acid and polyethylene glycol monomethyl ether having an average added mole number of oxyethylene groups (-CH2CH2O-) of 23 (MEPEG(23)MA) (ii) Polyethylene glycol (2-methyl-2-propenyl) ether represented by the following formula (1) (hereinafter referred to as HPEG55) [ka] [In the formula, p1 is the average number of moles of oxyethylene groups (-CH2CH2O-) added, which is 55.] (iii) polyethylene glycol isoprenyl ether (hereinafter referred to as TPEG60) represented by the following formula (2): [ka] [In the formula, p2 is the average number of moles of oxyethylene groups (-CH2CH2O-) added, which is 60.]

[0066] As the component (B), the following polyacrylic acids having different weight-average molecular weights (Mw) were used. Polyacrylic acid (Mw=2,000): Fujifilm Wako Pure Chemical Industries, Ltd. Polyacrylic acid (Mw=5,000): Fujifilm Wako Pure Chemical Industries, Ltd. Polyacrylic acid (Mw=25,000): Fujifilm Wako Pure Chemical Industries, Ltd.

[0067] Next, a method for producing the copolymer will be described. In the following, "parts" refers to "parts by mass" and "%" refers to "% by mass." Copolymers of MAA and MEPEG(23)MA were prepared as follows. 356 parts of ion-exchanged water was charged into a glass reaction vessel (four-neck flask) equipped with a stirrer, and the inside of the reaction vessel was replaced with nitrogen while stirring, and heated to 80°C under a nitrogen atmosphere. Next, a monomer aqueous solution obtained by mixing 318 parts of the above-mentioned MEPEG23, 67 parts of methacrylic acid, and 176 parts of ion-exchanged water, a mixed aqueous solution of 2.8 parts of 3-mercaptopropionic acid and 27.7 parts of ion-exchanged water, and a mixed aqueous solution of 3.3 parts of ammonium persulfate and 18.6 parts of ion-exchanged water were dropped over 2 hours, and after the dropwise addition, a mixed aqueous solution of 1.1 parts of ammonium persulfate and 6.2 parts of ion-exchanged water was further dropped over 0.5 hours. After the dropwise addition, the temperature was maintained at 80°C for 1 hour, and aging was performed. Thereafter, the reaction solution was neutralized using an aqueous sodium hydroxide solution at a temperature of 80°C or less to obtain an aqueous solution containing a copolymer having a weight average molecular weight of 45,000.

[0068] In addition, the copolymer of AA and TPEG(60) was prepared by the following procedure. 200 parts of TPEG60 and 128 parts of water were charged into a glass reaction vessel equipped with a stirrer, and the mixture was replaced with nitrogen while stirring, and the temperature was raised to 80°C in a nitrogen atmosphere. Then, 0.9 parts of hydrogen peroxide (35% aqueous solution) was added. An aqueous solution of 27.8 parts of acrylic acid dissolved in 41.7 parts of water and an aqueous solution of 1.4 parts of 3-mercaptopropionic acid dissolved in 45.4 parts of water were dropped into the vessel over 3 hours, and an aqueous solution of 0.4 parts of L-ascorbic acid dissolved in 38.4 parts of water was dropped into the vessel over 3.5 hours. Then, the mixture was aged at the same temperature (80°C) for 1 hour. After the aging, the mixture was neutralized with 16.1 parts of a 48% aqueous sodium hydroxide solution to obtain an aqueous solution containing a copolymer with a weight average molecular weight of 60,000. The copolymer of acrylic acid and HPEG (55) was produced according to the above-mentioned method.

[0069] In addition, the following compounds were used as comparative substances for component (B). Polyacrylic acid (Mw=250,000): Fujifilm Wako Pure Chemical Industries, Ltd. Sodium polymethacrylate (Mw=9,500): Sigma-Aldrich Co. Polyethylene glycol (PEG, Mw=20,000): Nacalai Tesque, Inc.

[0070] Table 1 shows the composition of each hydraulic composition dispersant used in the examples and comparative examples.

[0071] [Table 1]

[0072] <Preparation of mortar> The mortar (hydraulic composition) was prepared by mixing the following materials in the ratios shown in Table 2. Ordinary cement: A 1:1 mixture by weight of ordinary Portland cement manufactured by Taiheiyo Cement Co., Ltd. and ordinary Portland cement manufactured by Sumitomo Osaka Cement Co., Ltd. (density 3.16 g / cm 3 ) High-early-strength cement: High-early-strength Portland cement manufactured by Taiheiyo Cement Corporation Sand: Mountain sand, density 2.72g / cm 3

[0073] [Table 2]

[0074] <Preparation of mortar> Using a mortar mixer (Nishi Nippon Shikenki Co., Ltd., universal mixer, model: C-210, small mortar mixer), cement (C) and fine aggregate (S) were added and dry mixed for 10 seconds at a low rotation speed (63 rpm) of the mortar mixer, and mixing water (W) containing the prepared additive for clay-containing hydraulic composition was added. Then, main mixing was performed for 120 seconds at a low rotation speed (63 rpm) of the mortar mixer to prepare mortar. The dispersant for hydraulic composition was added to the mixing water so that the contents of components (A) and (B) were as shown in Table 3 per 100 parts by mass of cement.

[0075] The fluidity of the hydraulic composition was evaluated as follows. <Evaluation of the initial flow> The hydraulic composition immediately after kneading was filled into a flow cone (upper diameter 70 mm × lower diameter 100 mm × height 60 mm) described in JIS R5201, and the flow was measured on a 30 cm × 30 cm plastic plate, which was taken as the "initial flow value."

[0076] <Evaluation of shape retention> The hydraulic composition 15 minutes after mixing was filled into two flow cones (upper diameter 70 mm × lower diameter 100 mm × height 60 mm) specified in JIS R5201. The flow of one of the flow cones was immediately measured on a 30 cm × 30 cm plastic plate, and this was recorded as the flow value "immediately after filling." The other flow cone was left to stand for 2 minutes after filling, and the flow was measured on a 30 cm × 30 cm plastic plate, and this was recorded as the flow value "2 minutes after filling." Shape retention was calculated using the following formula. Shape retention = [immediately after filling - 2 minutes after filling] ÷ [immediately after filling] × 100 (%) From this formula, it is determined that the composition has better shape retention when the flow value 2 minutes after filling is smaller than that immediately after filling.

[0077] Table 3 shows the initial flow value, the flow value immediately after filling, the flow value 2 minutes after filling, and the shape retention of various examples and comparative examples.

[0078] [Table 3]

[0079] The initial flow values ​​of hydraulic compositions containing normal cement, to which a dispersant for hydraulic compositions containing methacrylic acid (MAA) as component (A1), MEPEG (23) MA as component (A2), and polyacrylic acid as component (B) was added, were almost the same at 200 to 209 mm (Examples 1 to 6). In addition, the flow values ​​immediately after filling after 15 minutes were also almost the same at 234 to 254 mm. The flow values ​​two minutes after filling all decreased to 211 to 228 mm, showing good shape retention of 9 to 11%.

[0080] The initial flow value and shape retention were examined for Comparative Example 1, in which the same component (A) as in Examples 1 to 6 was used, but no polyacrylic acid as the component (B) was added; Comparative Example 2, in which the mass ratio of the component (B) / component (A) was small; Comparative Example 3, in which the mass ratio of the component (B) / component (A) was large; Comparative Example 4, in which the Mw of the polyacrylic acid as the component (B) was large; and Comparative Example 5, in which sodium polymethacrylate was used as the component (B). The initial flow value of 192 to 204 mm and the flow value immediately after filling of 230 to 244 mm were comparable to those in Examples 1 to 6. On the other hand, the flow value 2 minutes after filling was 218 to 232 mm, a decrease from the flow value immediately after filling that was smaller than in Examples 1 to 6, and the shape retention was 5 to 7%.

[0081] As shown in Examples 7 and 8, even when the (A1) component and the (A2) component were replaced with acrylic acid (AA) and HPEG (55) or TPEG (60), the initial flow values ​​were 212 mm and 232 mm, which were similar to those in Examples 1 to 6. However, the flow values ​​immediately after filling were reduced to 207 mm and 170 mm. The flow values ​​2 minutes after filling were further reduced to 183 mm and 144 mm, and the shape retention was high at 12% and 15%.

[0082] On the other hand, as shown in Comparative Examples 6 and 7, when component (B) was removed from the hydraulic composition dispersants of Examples 7 and 8, the initial flow value and the flow value immediately after filling were similar to those of Examples 7 and 8, but the shape retention was reduced to 4% and 5%. Furthermore, as shown in Comparative Example 8, when the ratio of the structural unit (A1) to the total of all structural units of component (A) was set to 9 mass%, the shape retention was only 5%.

[0083] The above tendency was also observed when using hydraulic compositions containing high-early-strength cement. That is, in Examples 9 and 10, shape retention of 10% was observed, but the shape retention was reduced to 5% by using a dispersant excluding component (B) (Comparative Example 9), using a component (B) with a large Mw (Comparative Example 10), using polymethacrylic acid as component (B) (Comparative Example 11), and using polyethylene glycol (PEG), which is not a polycarboxylic acid, as component (B) (Comparative Example 12).

Claims

1. A dispersant for hydraulic compositions, comprising the following component (A) and component (B), wherein the content of the component (B) relative to the content of the component (A) is 0.1 mass% or more and 5 mass% or less. <Component (A)> A copolymer having a structural unit (A1) represented by the following formula (A1) and a structural unit (A2) represented by the following formula (A2), wherein the proportion of the structural unit (A1) relative to the total of all structural units of component (A), which is the sum of the structural units (A1) and (A2), is 11 mass% or more and less than 25 mass%. 【Chemistry 1】 [In the formula, R １ａ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. １ａ represents a hydrogen atom or a counter cation. 【Chemistry 2】 [In the formula, R ２ａ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ３ａ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ａ represents an alkylene group or a carbonyl group having 0 to 4 carbon atoms; AO represents an oxyalkylene group having 2 to 4 carbon atoms; and n a represents the average number of moles of AO added, which is a number of 5 to 150. <(B) component> A polyacrylic acid in which the hydrogen atom of the carboxy group may be substituted with a counter cation.

2. 2. The dispersant according to claim 1, wherein the weight average molecular weight of component (A) is 10,000 or more and 100,000 or less.

3. 3. The dispersant according to claim 1 or 2, wherein the weight average molecular weight of component (B) is 1,000 or more and 40,000 or less.

4. 3. The dispersant according to claim 1 or 2, wherein the weight average molecular weight of component (B) is 1,000 or more and 30,000 or less.

5. A hydraulic composition comprising hydraulic powder, aggregate, water, component (A) shown below, and component (B) shown below, wherein the content of component (B) relative to the content of component (A) is 0.1 mass% or more and 5 mass% or less. <Component (A)> A copolymer having a structural unit (A1) represented by the following formula (A1) and a structural unit (A2) represented by the following formula (A2), wherein the proportion of the structural unit (A1) relative to the total of all structural units of component (A), which is the sum of the structural units (A1) and (A2), is 11 mass% or more and less than 25 mass%. 【Chemistry 3】 [In the formula, R １ａ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. １ａ represents a hydrogen atom or a counter cation. 【Chemistry 4】 [In the formula, R ２ａ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ３ａ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ａ represents an alkylene group or a carbonyl group having 0 to 4 carbon atoms; AO represents an oxyalkylene group having 2 to 4 carbon atoms; and n a represents the average number of moles of AO added, which is 5 to 150. <(B) component> A polyacrylic acid in which the hydrogen atom of the carboxy group may be substituted with a counter cation.

6. 6. The hydraulic composition according to claim 5, wherein the weight average molecular weight of component (A) is 10,000 or more and 100,000 or less.

7. 7. The hydraulic composition according to claim 5 or 6, wherein the weight average molecular weight of component (B) is 1,000 or more and 40,000 or less.

8. 7. The hydraulic composition according to claim 5 or 6, wherein the weight average molecular weight of component (B) is 1,000 or more and 30,000 or less.

9. The hydraulic composition according to any one of claims 5 to 8, wherein the mass ratio of water to hydraulic powder, water / hydraulic powder, is 1 mass% or more and 45 mass% or less.

10. A method for producing a hydraulic composition, comprising mixing hydraulic powder, aggregate, water, and the following component (A) and component (B), wherein the amount of component (B) mixed relative to the amount of component (A) mixed is 0.1 mass% or more and 5 mass% or less. <Component (A)> A copolymer having a structural unit (A1) represented by the following formula (A1) and a structural unit (A2) represented by the following formula (A2), wherein the proportion of the structural unit (A1) relative to the total of all structural units of component (A), which is the sum of the structural units (A1) and (A2), is 11 mass% or more and less than 25 mass%. 【Chemistry 5】 [In the formula, R １ａ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. １ａ represents a hydrogen atom or a counter ion. 【Chemistry 6】 [In the formula, R ２ａ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ３ａ represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. ａ represents an alkylene group or a carbonyl group having 0 to 4 carbon atoms; AO represents an oxyalkylene group having 2 to 4 carbon atoms; and n a represents the average number of moles of AO added, which is 5 to 150. <(B) component> A polyacrylic acid in which the hydrogen atom of the carboxy group may be substituted with a counter cation.

11. The method for producing a hydraulic composition according to claim 10, wherein the weight average molecular weight of component (A) is 10,000 or more and 100,000 or less.

12. The method for producing a hydraulic composition according to claim 10 or 11, wherein the weight average molecular weight of component (B) is from 1,000 to 40,000.

13. The method for producing a hydraulic composition according to any one of claims 10 to 12, wherein the weight average molecular weight of component (B) is 1,000 or more and 30,000 or less.

14. The method for producing a hydraulic composition according to any one of claims 10 to 13, wherein a mass ratio of water to hydraulic powder, water / hydraulic powder, is 1 mass% or more and 45 mass% or less.

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