JP6415960B2 - Dispersant for hydraulic composition - Google Patents

Description

  The present invention relates to a dispersant for a hydraulic composition and a hydraulic composition.

  Admixtures such as naphthalene, melamine, aminosulfonic acid, and polycarboxylic acid are used to impart fluidity to hydraulic compositions such as concrete. For admixtures such as dispersants, various performances such as imparting fluidity to the hydraulic composition, fluidity retention (flow retention), prevention of curing delay, etc. are required. From this point of view, improvements have also been proposed for the dispersant.

  Patent Document 1 discloses that an ethylene-based monomer having a specific polyoxyalkylene group in an amount of 25 to 85% by weight, with the goal of exhibiting stable initial fluidity and fluidity retention regardless of the type of hydraulic powder. A hydraulic composition containing a copolymer obtained by polymerizing 10 to 70% by weight of a mono (meth) acrylic acid ester monomer and 5 to 20% by weight of a carboxylic acid monomer having an unsaturated bond Dispersants are disclosed.

  Further, Patent Document 2 discloses that specific alkyl (meth) acrylate monomers 20 to 60 mol%, polyalkylene glycol, with the problems of lowering the viscosity of concrete, improving slump retention, and reducing bleeding water. It is formed by polymerizing a monomer component of 15 to 40 mol% of an unsaturated monomer and 19 to 65 mol% of an unsaturated carboxylic acid (salt) monomer, and has a weight average molecular weight of 20000 or less. A featured polycarboxylic acid concrete admixture is disclosed.

  On the other hand, with respect to the initial fluidity and fluid retention effect of the polycarboxylic acid-based dispersant, the effect varies greatly depending on the aggregate used, and in the preparation of hydraulic compositions such as concrete, naphthalene, melamine, etc. Workability was inferior to that of other dispersants, and the required addition amount sometimes increased.

  Patent Document 3 discloses a clay activity and slump exhibited by a hydratable cementitious composition containing a clay-containing aggregate, in order to maintain the dose efficiency exhibited by a polycarboxylic acid-based dispersant in cement mortar or concrete. Disclosed are methods of combining certain cationic compounds and at least one poly-hydroxyl or hydroxyl carboxylic acid or salt thereof to improve retention.

  Patent Document 4 discloses that an ethylene-based monomer having a specific polyoxyalkylene group can be used to suppress an increase in initial fluidity regardless of the type of aggregate (sand) and to exhibit excellent fluidity. A copolymer obtained by polymerizing a monomer and a monomer having a carboxylic acid group and / or a phosphoric acid group, an ethylene monomer having a specific polyoxyalkylene group, and 2-hydroxyethyl acrylate An admixture for a hydraulic composition containing a copolymer having a weight average molecular weight of 6000 to 27000 obtained in this manner is disclosed. And it is described that the polyoxyalkylene group which a copolymer has is easy to adsorb | suck to sand, especially clay.

  Patent Document 3 is a technique in which a specific cationic compound and a hydroxycarboxylic acid are used in combination with a polycarboxylic acid polymer, and Patent Document 4 is a technique in which a polycarboxylic acid polymer and a specific polymer are used in combination.

JP 2009-96672 A JP-T-2006-525938 JP 2011-136844 A JP2013-133241A

  Concrete factories use a combination of various types of sand collected from different sites, which makes a difference in the amount of clay contained in concrete. For this reason, when the same addition amount is used in order to obtain a target flow, the same dispersibility cannot be expressed due to the difference in the amount of clay, resulting in discrete values. Some concrete factories do not have a solution because they have only one tank.

Therefore, the polycarboxylic acid polymer alone is included in the aggregate due to the complexity of adjusting the addition amount of the polycarboxylic acid dispersant according to the aggregate, the limitation due to the number of chemical tanks, and the simplification of the concrete preparation work. It is desirable not to be affected by clay components.

  The present invention provides a dispersant for a hydraulic composition comprising a polycarboxylic acid polymer that is less affected by the clay component contained in the aggregate and exhibits stable fluidity retention.

  In the present invention, in the total amount of the constituent monomers, the proportion of methacrylic acid is 13% by mass to 27% by mass, the proportion of the monomer represented by the general formula (1) is 55% by mass to 76% by mass, The ratio of the monomer selected from methyl acrylate, methyl methacrylate and hydroxyethyl acrylate (hereinafter referred to as monomer A) is 7% by mass or more and 15% by mass or less, and the weight average molecular weight is 28,000 or more and 100,000 or less. The present invention relates to a dispersant for a hydraulic composition comprising a copolymer (hereinafter sometimes referred to as a copolymer according to the present invention).

[Wherein, EO represents an ethyleneoxy group, n represents an average added mole number of EO, represents a number of 7 or more and 25 or less, and R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ]

Moreover, the present invention is a hydraulic composition containing hydraulic powder, aggregate, and water,
Containing 0.1 mass% or more and 5 mass% or less of clay in the aggregate,
Furthermore, the dispersant for a hydraulic composition of the present invention contains 0.02 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the hydraulic powder.
It relates to a hydraulic composition.

  ADVANTAGE OF THE INVENTION According to this invention, the dispersing agent for hydraulic compositions which consists of a polycarboxylic acid type polymer which relieve | moderates the influence of the clay component contained in an aggregate and expresses the stable fluidity retention is provided.

A binary copolymer obtained by copolymerizing ethylene glycol or alkoxy polyethylene glycol with an ester of methacrylic acid (hereinafter also referred to as MEPEG ester) and methacrylic acid (hereinafter also referred to as MAA) is obtained by changing the copolymerization ratio. Controls the adsorptivity to cement. However, since the ethylene glycol moiety of the MEPEG ester introduced as a steric repulsion group has the property of adsorbing to sand, especially clay components in the sand, the MAA / MEPEG ester copolymer can be efficiently adsorbed to cement. In addition, the dispersibility is considered to be different because the amount of clay component varies depending on the type of sand. And once the ethylene glycol part of MEPEG ester adsorbs to sand (clay component), it is considered that the cement dispersibility of the MAA / MEPEG ester copolymer is greatly reduced.
In the binary copolymer, when the amount of MEPEG ester adsorbed on sand (clay component) is decreased, MAA increases, and thus the adsorptivity changes suddenly and the adsorptivity to cement greatly changes.
In the present invention, a low-molecular specific monomer A such as methyl acrylate, which is a non-adsorbing component for cement and sand, is replaced with a part of the MEPEG ester as a third component, and three single monomers are used. By copolymerizing the body so as to have a predetermined ratio, it is considered that the adsorptivity to sand (clay component) can be suppressed while maintaining the adsorptivity to cement. Moreover, it is thought that the adsorptivity on the cement surface of a copolymer is ensured by using a copolymer with a weight average molecular weight of 28000 or more and 100,000 or less.

  The copolymer to be a dispersant for a hydraulic composition of the present invention is a copolymer of methacrylic acid, a monomer represented by the general formula (1), and a monomer containing monomer A under predetermined conditions. Obtained.

  The monomer represented by the general formula (1) is a monoester of methacrylic acid and polyethylene glycol or an ester of methacrylic acid and polyethylene glycol monoalkyl ether.

In the general formula (1), n is an average added mole number of ethyleneoxy group, which is 7 or more and 25 or less, preferably 8 or more, more preferably 9 or more, and further preferably 18 or more, and preferably The number is 24 or less, more preferably 23 or less.
In general formula (1), R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and preferably an alkyl group having 1 carbon atom.

  Monomer A is a monomer selected from methyl acrylate, methyl methacrylate, and hydroxyethyl acrylate. From the viewpoint of fluidity retention, the monomer A is preferably methyl acrylate.

In the copolymer according to the present invention, the proportion of methacrylic acid is 13% by mass or more and 27% by mass or less and the proportion of the monomer represented by the general formula (1) in the total amount of the constituent monomers of the copolymer. Is 55 mass% or more and 76 mass% or less, and the ratio of the monomer A is 7 mass% or more and 15 mass% or less.
In the total amount of the constituent monomers of the copolymer according to the present invention, the ratio of methacrylic acid is preferably 14% by mass or more, more preferably 15% by mass or more, and still more preferably, from the viewpoint of expressing stable fluidity retention. Is 17% by mass or more, and preferably 25% by mass or less, more preferably 23% by mass or less, and still more preferably 20% by mass or less.
In the total amount of the constituent monomers of the copolymer according to the present invention, the proportion of the monomer represented by the general formula (1) is preferably 57% by mass or more from the viewpoint of expressing stable fluidity retention, More preferably, it is 58 mass% or more, More preferably, it is 65 mass% or more, More preferably, it is 68 mass% or more, Preferably it is 75 mass% or less, More preferably, it is 74 mass% or less, More preferably, it is 71 mass% It is as follows.
In the total amount of the constituent monomers of the copolymer according to the present invention, the proportion of the monomer A is preferably 8% by mass or more, more preferably 9% by mass or more, from the viewpoint of expressing stable fluidity retention. More preferably, it is 12 mass% or more, and preferably 14 mass% or less.
In addition, the ratio of the monomer A in the total amount of the constituent monomers of the copolymer according to the present invention is preferably 8 from the viewpoint of expressing excellent fluidity retention while maintaining stable fluidity retention. It is at least 11% by mass, more preferably at least 11% by mass, even more preferably at least 13% by mass, and at most 15% by mass.

  In the total amount of the constituent monomers of the copolymer according to the present invention, the total ratio of the monomer represented by the general formula (1) and the monomer A is from the viewpoint of expressing stable fluidity retention. Preferably it is 73 mass% or more, More preferably, it is 75 mass% or more, More preferably, it is 77 mass% or more, More preferably, it is 80 mass% or more, Preferably it is 87 mass% or less, More preferably, it is 86 mass% or less More preferably, it is 85 mass% or less, and still more preferably 83 mass% or less.

  The copolymer according to the present invention is preferably 1 from the viewpoint that the mass ratio of methacrylic acid to monomer A [methacrylic acid / monomer A] exhibits stable fluidity retention on a monomer basis. .1 or more and 2.8 or less. This mass ratio is more preferably 1.15 or more, further preferably 1.25 or more, and more preferably 2.60 or less, still more preferably 2.50 or less, still more preferably 2.00 or less, More preferably, it is 1.50 or less.

  In the copolymer according to the present invention, the total amount of methacrylic acid, the monomer represented by the general formula (1), and the monomer A is preferably 95% by mass or more and 100% in the total amount of the constituent monomers. It is below mass%.

  The copolymer according to the present invention is obtained by copolymerizing methacrylic acid, the monomer represented by the general formula (1), and a monomer other than the monomer A (hereinafter referred to as the monomer 4). Also good. The ratio of the monomer 4 in all the constituent monomers of the copolymer is preferably 5% by mass or less, more preferably 2.5% by mass or less, and further preferably 1.0% by mass or less. It may be 0% by mass.

  As the monomer 4, phosphoric acid di-[(2-hydroxyethyl) methacrylic acid] ester, phosphoric acid di-[(2-hydroxyethyl) acrylic acid] ester, phosphoric acid mono (2-hydroxyethyl) methacrylic acid Ester, mono (2-hydroxyethyl) acrylate ester, polyalkylene glycol mono (meth) acrylate acid phosphate ester, and any one or more alkali metal salts, alkali Acid anhydrides such as earth metal salts, ammonium salts, amine salts and maleic anhydride may be used.

  Other monomers 4 include allyl sulfonic acid, methallyl sulfonic acid, any of these alkali metal salts, alkaline earth metal salts, ammonium salts, or amine salts, (meth) acrylamide, N-methyl (meth) Acrylamide, N, N-dimethyl (meth) acrylamide, 2- (meth) acrylamide-2-metasulfonic acid, 2- (meth) acrylamide-2-ethanesulfonic acid, 2- (meth) acrylamide-2-propanesulfonic acid, Examples thereof include monomers having acid groups of strong acids such as styrene and styrenesulfonic acid or neutralizing groups thereof.

  The copolymer according to the present invention can be produced by a known method. Examples thereof include solution polymerization methods described in JP-A-62-1119147 and JP-A-62-78137. That is, it is produced by polymerizing methacrylic acid, the monomer represented by the general formula (1), and the monomer A in the above ratio in an appropriate solvent. That is, the proportion of methacrylic acid is 13% by mass or more and 27% by mass or less, and the proportion of the monomer represented by the general formula (1) is 55% by mass or more in all monomers used for copolymerization. Polymerization is carried out at 76% by mass or less and the proportion of the monomer A is 7% by mass or more and 15% by mass.

  Examples of the solvent used in the solution polymerization method include water, methyl alcohol, ethyl alcohol, isopropyl alcohol, benzene, toluene, xylene, cyclohexane, n-hexane, ethyl acetate, acetone, and methyl ethyl ketone. In consideration of handling and reaction equipment, water and methyl alcohol, ethyl alcohol, and isopropyl alcohol are preferable.

  As an aqueous polymerization initiator, persulfuric acid ammonium salt or alkali metal salt or hydrogen peroxide, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (2-methylpropionamide) Water-soluble azo compounds such as dihydrate are used. For solution polymerization using a non-aqueous solvent, peroxides such as benzoyl peroxide and lauroyl peroxide, aliphatic azo compounds such as azobisisobutyronitrile, and the like are used.

  Examples of chain transfer agents include thiol chain transfer agents and halogenated hydrocarbon chain transfer agents, and thiol chain transfer agents are preferred.

As the thiol chain transfer agent, those having a —SH group are preferable, and in particular, the general formula HS—R—Eg (wherein R represents a hydrocarbon-derived group having 1 to 4 carbon atoms, and E is − OH, —COOM, —COOR ′ or —SO ₃ M group, M represents a hydrogen atom, monovalent metal, divalent metal, ammonium group or organic amine group, and R ′ represents an alkyl having 1 to 10 carbon atoms. In which g represents an integer of 1 to 2, for example, mercaptoethanol, thioglycerol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, Examples include octyl thioglycolate, octyl 3-mercaptopropionate, and the like from the viewpoint of chain transfer effect in a copolymerization reaction including monomers 1 to 3. Mercaptoethanol are preferable, more preferably mercaptopropionic acid. These 1 type (s) or 2 or more types can be used.

  Examples of the halogenated hydrocarbon chain transfer agent include carbon tetrachloride and carbon tetrabromide.

  Examples of other chain transfer agents include α-methylstyrene dimer, terpinolene, α-terpinene, γ-terpinene, dipentene, 2-aminopropan-1-ol and the like. A chain transfer agent can use 1 type (s) or 2 or more types.

  An example of the manufacturing method of the copolymer which concerns on this invention is shown. A predetermined amount of water is charged into a reaction vessel, the atmosphere is replaced with an inert gas such as nitrogen, and the temperature is raised. Prepare in advance methacrylic acid, the monomer represented by the general formula (1), monomer A, and chain transfer agent mixed and dissolved in water, and those prepared by dissolving the polymerization initiator in water. It is dripped at reaction container over 5 to 5 hours. At that time, each monomer, chain transfer agent and polymerization initiator may be dropped separately, or a mixed solution of monomers can be charged in a reaction vessel in advance and only the polymerization initiator can be dropped. is there. That is, the chain transfer agent, the polymerization initiator, and other additives may be added as an additive solution separately from the monomer solution, or may be added to the monomer solution after being added. From the viewpoint of stability, it is preferable to supply the reaction system as an additive solution separately from the monomer solution. Further, aging is preferably performed for a predetermined time. The polymerization initiator may be added dropwise at the same time as the monomer, or may be added in portions, but it is preferable to add in portions in terms of reducing unreacted monomers. For example, in the total amount of the polymerization initiator to be finally used, 1/2 to 2/3 polymerization initiator is added simultaneously with the monomer, and the remainder is aged for 1 to 2 hours after the completion of the monomer dropping, It is preferable to add. If necessary, the copolymer according to the present invention is obtained by further neutralizing with an alkali agent (such as sodium hydroxide) after completion of aging.

  Further, the copolymer according to the present invention reacts with a liquid A containing methacrylic acid, a liquid B containing a monomer represented by the general formula (1), and a liquid C containing a monomer A. It can also be introduced into the system and used for the copolymerization reaction, and liquid A, liquid B and liquid C can be introduced separately into the reaction system. Moreover, it is preferable to introduce 90% by mass or more of each of the total amount of the liquid A, the liquid B, and the liquid C introduced into the reaction system in parallel into the reaction system. Specific examples of the method for introducing the liquid A, the liquid B, and the liquid C into the reaction system include dropping and spraying, and the dropping is preferable from the viewpoint of the viscosity of the liquid A, the liquid B, and the liquid C. The liquid A is preferably a solvent containing water from the viewpoint of the freezing point, and the liquid B is preferably a solvent not containing water from the viewpoint of hydrolysis. The distance between the nozzle for liquid A (introduction port), the nozzle for liquid B (introduction port), and the nozzle for liquid C (introduction port) can be set arbitrarily. Moreover, although dripping can be carried out in air or in liquid, air dripping is preferred from the viewpoint of introducing all of the liquid. The nozzle diameter is preferably smaller from the viewpoint of increasing the surface area of the droplet and the solubility. Thus, by introducing the liquid A and the liquid B separately into the reaction system, the opportunity of contact of the monomer 2 with water is reduced and hydrolysis is suppressed. In addition, by introducing 90% by mass or more of the total amount of liquid A, liquid B, and liquid C introduced into the reaction system in parallel into the reaction system, a copolymer in which each monomer is randomly introduced is obtained. can get. In other words, 90% by mass or more of the total amount of the liquid A, the liquid B, and the liquid C means that the amount of the liquid A, the liquid B, and the liquid C that are independently introduced into the reaction system is the liquid A that is introduced into the reaction system. , Liquid B and liquid C are each 10% by mass or less.

  Further, in the production of the copolymer according to the present invention, from the viewpoint of versatility with respect to materials, temperature and blending, methacrylic acid, the monomer represented by the general formula (1), monomer A Polymerization can be performed by changing the copolymerization molar ratio one or more times.

  The weight average molecular weight of the copolymer in the present invention is 28000 or more and 100,000 or less from the viewpoint that the influence of the clay component contained in the aggregate is alleviated and stable fluidity is expressed. The weight average molecular weight of the copolymer is preferably 30000 or more, more preferably 35000 or more, and preferably 80000 or less, more preferably 60000 or less. This weight average molecular weight is measured by the gel permeation chromatography method under the conditions of the examples.

  The dispersant for hydraulic composition of the present invention can be used as an aqueous solution containing the copolymer.

  The dispersant of the present invention is for a hydraulic composition. The hydraulic composition contains hydraulic powder and water, and examples thereof include paste, mortar, and concrete. The hydraulic powder is a powder having physical properties that are cured by a hydration reaction, and examples thereof include cement and gypsum. The dispersant of the present invention is suitable as a dispersant for hydraulic compositions containing cement. The hydraulic powder is preferably ordinary portland cement, belite, cemented medium heat cement, early strong cement, super early strong cement, sulfuric acid resistant cement, etc., and blast furnace slag, fly ash, silica fume, stone powder. Blast furnace slag cement, fly ash cement, silica fume cement or the like to which (calcium carbonate powder) or the like is added may be used.

<Dispersant for hydraulic composition>
The dispersant for a hydraulic composition of the present invention can use the copolymer according to the present invention alone, but at least selected from a carboxylic acid group, a phosphoric acid group, a sulfonic acid group, and a neutralizing group thereof. You may use together the polymer A which has 1 type (henceforth the polymer A). In general, the polymer A is a polymer known as an admixture (dispersant or the like) for a hydraulic composition. The hydraulic composition dispersant of the present invention can be used as an aqueous solution containing the dispersant of the present invention and the polymer A.

  Among the polymers A, those having a carboxylic acid group or a neutralizing group thereof are polymers having an oxyalkylene group or a polyoxyalkylene group and a carboxylic acid. For example, a polyalkylene glycol monoester monomer and an acrylic acid polymer into which 110 to 300 moles of an oxyalkylene group having 2 to 3 carbon atoms shown in JP-A-7-223852 are introduced, JP-A-2004-519406. Japanese Patent Application Laid-Open No. 2004-210587, Japanese Patent Application Laid-Open No. 2004-210589, and an amide macromonomer described in Japanese Patent Application Laid-Open No. 2004-210589 -1288738 gazette and JP, 2006-525219, A polymer containing polyethyleneimine is mentioned.

  Examples of commercially available polymers A having a carboxylic acid group or a neutralizing group thereof include (1) BASF Pozzolith Co., Ltd. Leo Build SP8LS / 8LSR, SP8LS, SP8LSR, SP8N, SP8S, SP8R, SP8SE / 8RE, SP8SE, SP8RE , SP8SB series (S type, M type, L type, LL type), SP8HE, SP8HR, SP8SV / 8RV, SP8RV, SP8HU, SP9N, SP9R, SP9HS, Leo build 8000 series, (2) Nihon Sika Co., Ltd. SeaCament 1100NT , Sea Kament 1100NTR, Sea Kament 2300, (3) Floric's Floric SF500S (500SB), Floric SF500H, Floric SF500R (500RB), (4) Tulip HP-8, HP -11, HP-8R, HP-11R, SSP-104, NV-G1, NV-G5, (5) Nippon Catalyst's Aqualock FC600S, Aqualock FC900, (6) Maria Lim, Nippon Oil & Fats Co., Ltd. AKM, Mariarim EKM, etc. are mentioned, but not limited to this.

  The polymer A having a phosphate group or a neutralizing group thereof is a polymer having a polyoxyalkylene group and a phosphate group. For example, the polymer of Unexamined-Japanese-Patent No. 2006-052381 is mentioned. Specifically, a polyalkylene glycol monoester monomer introduced with an average of 3 to 200 moles of an oxyalkylene group having 2 to 3 carbon atoms, di-[(2-hydroxyethyl) methacrylic acid] ester phosphate, And a copolymer with mono (2-hydroxyethyl) methacrylate ester.

  Among the polymers A, those having a sulfonic acid group or a neutralizing group thereof include naphthalene polymers (for example, Mighty 150: manufactured by Kao Corporation), melamine polymers (for example, Mighty 150V-2: Kao Corporation) ) And aminosulfonic acid polymers (for example, PARIC FP: manufactured by Fujisawa Chemical Co., Ltd.).

  In addition to the copolymer and polymer A according to the present invention, the dispersant for a hydraulic composition of the present invention includes, for example, a high performance water reducing agent, AE agent, AE water reducing agent, fluidizing agent, retarder, early strength. Agents, accelerators, foaming agents, foaming agents, antifoaming agents, thickeners, waterproofing agents, and antifoaming agents can be used in combination.

<Hydraulic composition>
The hydraulic composition of the present invention contains hydraulic powder, aggregate, water, and a predetermined amount of the dispersant for hydraulic composition of the present invention, and 0.1% by mass in the aggregate. More than 5 mass% clay is contained. Further, the polymer A may be contained. When obtaining the hydraulic composition of the present invention, the dispersant for hydraulic composition of the present invention and the polymer A may be mixed in advance or used separately.

  The hydraulic powder used in the hydraulic composition of the present invention is a powder having physical properties that are cured by a hydration reaction, and examples thereof include cement and gypsum. Preferred are ordinary Portland cement, Belite cement, moderate heat cement, early strong cement, super early strong cement, sulfuric acid resistant cement, etc., and blast furnace slag, fly ash, silica fume, stone powder (calcium carbonate powder), etc. Blast furnace slag cement, fly ash cement, silica fume cement or the like to which is added may be used. In addition, the hydraulic composition finally obtained by adding sand, sand and gravel as aggregates to these powders is generally called mortar, concrete, etc., respectively. The dispersant for a hydraulic composition of the present invention expresses the fluidity retention of the hydraulic composition even when clay is contained in the aggregate, and the fluctuation of the fluidity retention is less than when no clay is contained. . Therefore, it is more effective for hydraulic compositions using aggregates containing clay. The content of clay in the aggregate is 0.1% by mass or more, preferably 0.5% by mass or more, and preferably from the viewpoint of exerting the effect of the dispersant for hydraulic composition of the present invention. It is 5 mass% or less, More preferably, it is 3 mass% or less.

  The hydraulic composition of the present invention has a water / hydraulic powder ratio [mass percentage (mass%) of water and hydraulic powder in the slurry, usually abbreviated as W / P. , W / C may be abbreviated. Is preferably 60% by mass or less, more preferably 58% by mass or less, still more preferably 57% by mass or less, still more preferably 56% by mass or less, still more preferably 55% by mass or less, and preferably 15 mass% or more, More preferably, it is 18 mass% or more, More preferably, it is 20 mass% or more, More preferably, it is 23 mass% or more.

  Moreover, when the average addition mole number of the ethyleneoxy group of the monomer represented by the general formula (1) is 18 or more, W / P and W / C are preferably 60% by mass or less, more preferably It is 58 mass% or less, More preferably, it is 56 mass% or less, More preferably, it is 55 mass% or less, Preferably it is 15 mass% or more, More preferably, it is 18 mass% or more, More preferably, it is 20 mass% or more, More preferably Can be 23% by weight or more.

  When the average addition mole number of the ethyleneoxy group of the monomer represented by the general formula (1) is less than 18, W / P and W / C are preferably 60% by mass or less, more preferably 59% by mass or less, more preferably 58% by mass or less, still more preferably 55% by mass or less, still more preferably 52% by mass or less, and preferably 30% by mass or more, more preferably 35% by mass or more, More preferably, it is 37 mass% or more, More preferably, it can be 40 mass% or more.

In the hydraulic composition of the present invention, the content of the dispersant for the hydraulic composition of the present invention, that is, the copolymer according to the present invention (in terms of solid content) is preferably based on 100 parts by mass of the hydraulic powder. Is 0.02 parts by mass or more, more preferably 0.05 parts by mass or more, still more preferably 0.10 parts by mass or more, still more preferably 0.30 parts by mass or more, and preferably 5 parts by mass or less. More preferably, it is 3 parts by mass or less, further preferably 2 parts by mass or less, and still more preferably 1 part by mass or less.
In the hydraulic composition of the present invention, the content of the polymer A is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more with respect to 100 parts by mass of the hydraulic powder. And, it is preferably 4 parts by mass or less, more preferably 2 parts by mass or less, still more preferably 1 part by mass or less.

  The hydraulic composition of the present invention is used in the field of ready-mixed concrete, concrete vibration products, self-leveling, refractory, plaster, gypsum slurry, lightweight or heavy concrete, AE, repair, pre-packed, tray It is useful in any field of various concrete such as for grouting, for ground improvement, for cold weather.

  Particularly, in the production site of ready-mixed concrete, various kinds of aggregates collected from different sites are used in combination, and the amount of clay contained in the concrete varies. In such a situation, it is meaningful to provide general-purpose fluidity retention with little variation in fluidity retention even if the production area of the aggregate is different.

<Example of copolymer production>
Copolymer 6 was synthesized by the following method. Other copolymers in the table were synthesized in the same manner.
176.32 g of ion-exchanged water was charged into a 1 L four-necked flask, and the temperature was raised to 80 ° C. while stirring with a Teflon (registered trademark) stirring blade. Methoxypolyethyleneglycol (ethylene oxide average addition mole number 23) monomethacrylate aqueous solution 1861.3g (the water is 34.65 mass%, the effective part is 1216.36g), methacrylic acid 406.43g, methyl acrylate 180.39g, A mixture of 2543.7 g of the monomer mixture mixed with 1,5,6 g of 3-mercaptopropionic acid dissolved in 125 g of ion-exchanged water in 1.5 hours, and ion-exchanged 27.06 g of ammonium persulfate aqueous solution in 1.5 hours. An aqueous solution dissolved in 200 g of water was dropped from each dropping funnel in 1.5 hours. While maintaining the temperature, an aqueous solution prepared by dissolving 9.02 g of an aqueous ammonium persulfate solution in 100 g of ion-exchanged water was added dropwise over 0.5 hours. Thereafter, aging was performed for 1 hour while maintaining the temperature, and the polymerization reaction was completed. The mixture was cooled to 60 ° C. and neutralized with 196.69 g of 48% by mass sodium hydroxide. The weight average molecular weight of the obtained copolymer 6 was 42,000. The weight average molecular weight was measured by the following method using gel permeation chromatography.

[Measurement method of weight average molecular weight]
Column used: TSK guard column PWxl manufactured by Tosoh Corporation
TSKgel G4000PWxl + G2500PWxl
Eluent: 0.2 mol / L phosphate buffer (manufactured by Shinyo Chemical Co., Ltd.) / Acetonitrile for high performance liquid chromatography (manufactured by Wako Pure Chemical Industries, Ltd.) = 9/1 (vol%)
Flow rate: 1.0mL / min.
Column temperature: 40 ° C
Detection: RI
Injection volume: 10 μL (0.5 mass% aqueous solution)
Standard substance: monodisperse polyethylene glycol of known molecular weight, molecular weight (Mw) 875000, 540000, 235000, 145000, 107000, 24000
Calibration curve order: Tertiary device: HLC-8320GPC (manufactured by Tosoh Corporation)
Software: EcoSEC-WS (manufactured by Tosoh Corporation)

In addition, the symbol in a table | surface has the following meaning.
MAA: methacrylic acid ME (23) ester: methoxypolyethylene glycol (average number of moles of ethylene oxide added: 23) monomethacrylate [monomer of general formula (1) where n is 23 and R is a methyl group]
ME (9) ester: methoxy polyethylene glycol (average number of moles of added ethylene oxide 9) monomethacrylate [monomer in which n is 9 and R is methyl group in general formula (1)]
MA: methyl acrylate MMA: methyl methacrylate MW: weight average molecular weight

<Mortar formulation>
Two mortar formulations with W / C = 35% and W / C = 45% were prepared. The evaluation results of the mortar formulation with W / C = 35% are shown in Table 2, and the evaluation results of the mortar formulation with W / C = 45% are shown in Table 3.
Each basic composition was as follows. In addition, mortar blending using sand in which part of the standard blend standard sand was replaced with Kasaoka clay was also evaluated. 1% or 3% by weight of standard sand was replaced with Kasaoka clay. For example, when 1% by mass of clay was replaced with 1350 g of standard sand, 1336.5 g of standard sand and 13.5 g of clay were mixed to prepare 1350 g of standard sand containing clay. The results of mortar blending using Kasaoka clay are shown in Tables 2 and 3 as “Kasaoka Clay 1% by mass substitution” or “Kasaoka Clay 3% by mass substitution”.

<Evaluation of fluidity retention>
Mortar was prepared with the mortar formulation shown in Table 1 using the dispersants shown in Tables 2 and 3, and the fluidity was evaluated.
Using a mortar mixer (manufactured by Kansai Kikai Seisakusho: KC-8), materials were added in the order of 675 g of sand, 800 g of cement (manufactured by Taiheiyo Cement Co., Ltd .: ordinary Portland cement) and 675 g of sand, and then kneaded at low speed for 10 seconds. Then, kneaded water was added and stirred at low speed for 2 minutes to prepare mortar. In addition, the kneading water used what added beforehand the kind and quantity of dispersing agent shown in Table 2 or Table 3 to water. As the addition amount of the dispersing agent, an amount at which the flow of mortar immediately after preparation was 210 mm was used. The amount at which the flow was 210 mm was determined by measuring the flow of two or three mortars with different addition amounts in advance and approximating the relationship between the addition amount and flow with a straight line.
The flow was measured for the mortar immediately after preparation and the mortar 60 minutes after preparation. For the flow, a mortar cone (lower inner diameter 100 mm, upper inner diameter 70 mm, height 60 mm) was used, and the spread (diameter) when pulled up vertically was defined as the flow. From the flow immediately after preparation and the flow after 60 minutes of preparation, the retention after 60 minutes was calculated by the following formula.
Retention rate after 60 minutes (%) = [flow after 60 minutes (mm) / flow immediately after preparation (mm)] × 100
Moreover, the retention ratio was calculated by the following formula as an index of the influence of clay content on the retention. The closer this value is to 1, the less affected by clay.
Retention ratio = [Retention ratio after 60 minutes when using 3% by weight substitution of Kasaoka clay (%)] / [Retention ratio after 60 minutes when using standard sand (%)]

<Method for evaluating storage stability>
An aqueous solution containing the copolymers of Tables 2 and 3 at a concentration of 40% by mass was stored in a 300 mL glass sample tube and stored at room temperature (25 ° C.) for 30 days. After storage, the presence or absence of separation was determined by visual observation. The case where separation did not occur was designated as “◯”, and the case where separation occurred was designated as “x”.

* 1 The amount of dispersant added is part by mass with respect to 100 parts by mass of cement.
* 2 In some comparative examples, even if the amount of dispersant added was increased, kneading was impossible and mortar could not be prepared, so fluidity retention was not evaluated.

  In the evaluation of 35% by mass of W / C, the dispersants of Examples 1-1 to 1-7 have a retention ratio closer to 1 than Comparative Examples 1-1 to 1-4 and 1-6, and the influence of clay. It turns out that it is hard to receive. It can be seen that Comparative Example 1-7 in which 20% by mass of methyl acrylate is inferior in storage stability. Moreover, in Comparative Examples 1-5 and 1-8 in which methacrylic acid was about 10% by mass, mortar could not be kneaded.

* 1 The amount of dispersant added is part by mass with respect to 100 parts by mass of cement.

  In the evaluation of 45% by mass of W / C, the dispersants of Examples 2-1 to 2-3 have a retention ratio close to 1 and less susceptible to clay than Comparative Examples 2-1 to 2-5. I understand. Comparative Example 2-1 using Comparative Copolymer 5 with about 10% by weight of methacrylic acid that could not be kneaded at a W / C of 35 could be kneaded at a W / C of 45% by weight. It can be seen that the retention ratio is poor and the influence of clay is large.

Claims (5)

In a total volume of constituent monomer, the proportion of methacrylic acid 13 wt% or more 27 wt% or less, the general formula (1) 76% by weight proportion of monomer 55 mass% or more represented by the following acrylic acid methylation A dispersant for a hydraulic composition comprising a copolymer having a weight average molecular weight of 28000 or more and 100,000 or less, wherein the ratio ( hereinafter referred to as monomer A) is 7% by mass or more and 15% by mass or less.

[Wherein, EO represents an ethyleneoxy group, n represents an average added mole number of EO, represents a number of 7 or more and 25 or less, and R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ]   2. The water according to claim 1, wherein the weight ratio [methacrylic acid / monomer A] of methacrylic acid and monomer A in the copolymer is 1.1 or more and 2.8 or less on a monomer basis. Dispersant for hard composition.   In the total amount of constituent monomers of the copolymer, the total of methacrylic acid, the monomer represented by the general formula (1), and the monomer A is 95% by mass or more and 100% by mass or less. The dispersant for hydraulic compositions according to claim 1 or 2.   The total ratio of the monomer represented by the general formula (1) and the monomer A in the total amount of the constituent monomers of the copolymer is 73% by mass or more and 87% by mass or less. The dispersing agent for hydraulic compositions in any one of -3. A hydraulic composition containing hydraulic powder, aggregate, and water,
Containing 0.1 mass% or more and 5 mass% or less of clay in the aggregate,
Furthermore, the dispersant for a hydraulic composition according to any one of claims 1 to 4 is contained in an amount of 0.02 parts by mass to 5 parts by mass with respect to 100 parts by mass of the hydraulic powder.
Hydraulic composition.