JP7495556B2 - Polymers and cement admixtures - Google Patents

Description

The present invention relates to a polymer and a cement admixture. More specifically, the present invention relates to a polymer that can be suitably used in cement compositions such as cement paste, mortar, and concrete, and a cement admixture containing the polymer.

Cement admixtures are used to reduce water in cement compositions such as cement paste, mortar, and concrete, and to increase their fluidity. In addition to water-reducing properties, cement admixtures are also required to have qualities such as workability during construction of buildings, and strength and durability of the hardened product, so various investigations are currently being conducted.

Conventionally, naphthalene-based water-reducing agents have been used as cement admixtures, but polycarboxylic acid-based water-reducing agents containing (poly)oxyalkylene chains have been proposed. (Poly)oxyalkylene chains act as dispersing groups that disperse cement particles due to their steric repulsion, and are therefore effective in improving the fluidity of cement compositions.

As a polycarboxylic acid-based water-reducing agent containing a (poly)oxyalkylene chain, for example, a polycarboxylic acid-based water-reducing agent obtained by reacting ethylene oxide or the like with the hydroxyl group portion of methallyl alcohol or 3-methyl-3-butene-1-ol has been reported (Patent Documents 1 and 2).

JP 2015-157761 A JP 2014-166948 A

The polycarboxylic acid-based water-reducing agents containing the above-mentioned (poly)oxyalkylene chains have one (poly)oxyalkylene chain in the corresponding monomer. However, when these polymers are used for the purpose of controlling the quality such as the water-reducing performance of the cement admixture or the fluidity of the cement composition, the content of the (poly)oxyalkylene chain depends on the degree of polymerization of the (poly)oxyalkylene group contained in the monomer, and there is no way other than to control this degree of polymerization. Therefore, the degree of freedom in designing and blending cement compositions using cement admixtures containing these polymers is small, and there is also a limit to improving the performance such as the fluidity of the cement composition.

The present invention has been made in consideration of the above problems, and aims to provide a water-soluble polymer suitable for use as a cement admixture, a cement admixture with excellent water-reducing performance, a cement composition with excellent fluidity, and a cement obtained by hardening the cement composition.

As a result of intensive research, the inventors have discovered that the water-reducing performance of a cement admixture can be improved by using a polymer whose monomer is a compound having two or more (poly)oxyalkylene chains in the molecule, and that the use of this cement water-reducing agent in a cement composition improves the fluidity of the cement composition. Based on this knowledge, they have conducted further research and completed the present invention.

The present invention provides the following [1] to [11].
[1] A polymer comprising a structural unit derived from the following general formula (I) and a structural unit derived from the following general formula (II):
[In general formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a methyl group or an ethyl group, R _a represents an alkylene group having 2 to 18 carbon atoms, n represents an integer of 0 to 3, o represents an integer of 1 to 200, and p represents an integer of 1 to 3.]
[In general formula (II), R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom or a methyl group, and M represents at least one selected from the group consisting of a hydrogen atom, a monovalent metal atom, a divalent metal atom and ammonium.]
[2] A polymer comprising a structural unit derived from general formula (II) and a structural unit derived from the following general formula (III):
[In general formula (III), ^R8 and ^R9 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, _Rb and _Rc each independently represent an alkylene group having 2 to 18 carbon atoms, l represents an integer of 0 to 4, and m represents an integer of 1 to 200.]
[3] The polymer according to [1], further comprising a structural unit derived from general formula (III).
[4] The polymer according to any one of [1] to [3], wherein in general formula (II), M is at least one selected from the group consisting of a hydrogen atom, a monovalent metal atom, and a divalent metal atom.
[5] The polymer according to any one of [1], [3], and [ ⁴ ], in which, in general formula (I), R ¹ , R ² , and R 4 are hydrogen atoms, R ³ is a methyl group, R _a is an ethylene group, n is 1, and p is 2 or 3.
[6] The polymer according to any one of [2] to [5], wherein in general formula (III), R ⁸ and R ⁹ are hydrogen atoms, R _b and R _c are ethylene groups, and l is 2.
[7] A cement admixture comprising the polymer according to any one of [1] to [6].
[8] A cement composition comprising the cement admixture according to [7].
[9] Concrete obtained by hardening the cement composition according to [8].
[10] A compound represented by the following general formula (IV):
[In general formula (IV), o represents an integer of 1 to 200, and p is 2 or 3.]
[11] A compound represented by the following general formula (V):
[In general formula (V), R _b and R _c each independently represent an alkylene group having 2 to 18 carbon atoms, l represents an integer of 0 to 4, and m represents an integer of 1 to 200.]

The present invention provides a water-soluble polymer suitable for use as a cement admixture, a cement admixture with excellent water-reducing performance, a cement composition with excellent fluidity, and concrete obtained by hardening the cement composition.

[Polymer]
The present invention relates to a polymer containing a structural unit derived from the following general formula (I) and a structural unit derived from the following general formula (II). This polymer has particularly excellent solubility in water and excellent miscibility with cement compositions.

In general formula (I), R ¹ , R ² , R ³ and R ⁴ each independently represent a hydrogen atom, a methyl group or an ethyl group, and R _a represents an alkylene group having 2 to 18 carbon atoms, n represents an integer of 0 to 3, o represents an integer of 1 to 200, and p represents an integer of 1 to 3.

In general formula (I), examples of the alkylene group having 2 to 18 carbon atoms include linear alkylene groups such as ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, and n-decylene, and branched alkylene groups such as 2-methylpropylene, 2-methylhexylene, and tetramethylethylene, and these may be used alone or in combination of two or more.

In the general formula (I), o is the average number of moles of oxyalkylene groups (R _a O) added. The average number of moles added is 1 to 200, preferably 1 to 80, more preferably 4 to 70, even more preferably 4 to 70, and particularly preferably 4 to 60. If o is less than 1, sufficient cement dispersion performance is not exhibited, which is not preferable. On the other hand, if o exceeds 200, the viscosity increases when the cement composition is made, and the composition tends to be difficult to handle. In addition, in this specification, the "average number of moles added" means the arithmetic mean value of the number of moles of oxyalkylene groups added in 1 mole of each component of the general formula (I) and the general formula (III) described later. In addition, when o is a number of 2 or more, two or more oxyalkylene groups represented by R _a O in the general formula (I) are necessarily present in the same compound, but when there are two or more oxyalkylene groups, each of them may have any form such as random, block, or alternating.

In general formula (I), from the viewpoints of good solubility in water and of being able to introduce two oxyalkylene groups in one molecule while maintaining the reactivity of the double bond moiety during polymerization, it is preferable that R ¹ , R ² and R ⁴ are hydrogen atoms, R ³ is a methyl group, R _a is an ethylene group, n is 1, and p is 2 or 3.

In order to introduce a structural unit derived from general formula (I) into a polymer, it is preferable to use a compound represented by the following general formula (IV). By using this compound, it is possible to improve productivity with excellent volumetric efficiency, and two oxyalkylene groups can be introduced in one molecule while maintaining the reactivity of the double bond portion during polymerization.

In general formula (IV), o represents any integer from 1 to 200, and p is 2 or 3.

In general formula (II), ^R5 , ^R6 and ^R7 each independently represent a hydrogen atom or a methyl group, and M represents one selected from the group consisting of a hydrogen atom, a monovalent metal atom, a divalent metal atom and ammonium. That is, general formula (II) forms an ion pair.

In general formula (II), examples of monovalent metal atoms include alkali metal atoms such as lithium, sodium, and potassium, and examples of divalent metal atoms include alkaline earth metal atoms such as calcium and magnesium.

In general formula (II), ammonium is a molecular monovalent cation containing a nitrogen atom and may contain a hydrogen atom. Examples of such ammonium include alkyl ammonium such as methylammonium, ethylammonium, dimethylammonium, diethylammonium, trimethylammonium, and triethylammonium; and alkanol ammonium such as ethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, hydroxyethyldiisopropanolamine, dihydroxyethylisopropanolamine, tetrakis(2-hydroxypropyl)ethylenediamine, and pentakis(2-hydroxypropyl)diethylenetriamine.

In general formula (II), from the viewpoint of availability, M is preferably one selected from the group consisting of a hydrogen atom, a monovalent metal atom, and a divalent metal atom, and more preferably a hydrogen atom or sodium.

Specific examples of the unsaturated carboxylic acid monomer represented by general formula (II) include acrylic acid, methacrylic acid, sodium acrylate, sodium methacrylate, ammonium acrylate, ammonium methacrylate, etc., and two or more of these may be used in combination.

As the unsaturated carboxylic acid monomer, (meth)acrylic acid is preferably used, and methacrylic acid is most preferably used. These compounds may be commercially available compounds.

The present invention relates to a polymer that contains a structural unit derived from the above general formula (II) and a structural unit derived from the following general formula (III), and this polymer has particularly excellent solubility in water and excellent miscibility with cement compositions.

In formula (III), ^R8 and ^R9 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, _Rb and _Rc each independently represent an alkylene group having 2 to 18 carbon atoms, l represents an integer of 0 to 4, and m represents an integer of 1 to 200.

In the present invention, examples and preferred embodiments of general formula (II) are the same as those of the polymer containing the structural unit derived from general formula (I) above and the structural unit derived from general formula (II) below.

In general formula (III), examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a pentyl group, and a hexyl group.

In general formula (III), examples of the alkylene group having 2 to 18 carbon atoms include linear alkylene groups such as ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, and n-decylene, and branched alkylene groups such as 2-methylpropylene, 2-methylhexylene, and tetramethylethylene, and these may be used alone or in combination of two or more.

In the general formula (III) and the general formula (V) described later, m is the average number of moles of oxyalkylene groups (R _b O and R _c O). The average number of moles is a number from 1 to 200, preferably a number from 1 to 80, more preferably a number from 4 to 70, even more preferably a number from 4 to 70, and even more preferably a number from 4 to 60. When m is less than 1, sufficient cement dispersion performance is not exhibited, which is not preferable. On the other hand, when m exceeds 200, the viscosity increases when it is made into a cement composition, and it tends to be difficult to handle. Each of the oxyalkylene groups represented by R _b O and R _c O may have any addition form such as random addition, block addition, or alternating addition.

In general formula (III), from the viewpoint of having sufficient polymerizability and introducing two oxyalkylene groups per molecule, R ⁸ and R ⁹ are preferably each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, even more preferably each independently a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and still more preferably a hydrogen atom.

In the general formula (III), from the viewpoint of easy availability of raw materials, it is preferred that R ⁸ and R ⁹ are hydrogen atoms, R _b and R _c are ethylene groups, and l is 2.

In order to introduce a structural unit derived from general formula (III) into a polymer, it is preferable to use a compound represented by the following general formula (V). By using this compound, two oxyalkylene groups can be introduced per molecule while maintaining sufficient polymerizability, resulting in a polymer with a high oxyalkylene group density.

In formula (V), R _b and R _c each independently represent an alkylene group having 2 to 18 carbon atoms, l represents an arbitrary integer of 0 to 4, and m represents an arbitrary integer of 1 to 200.

The monomers represented by the general formula (I) or (III) can be produced by various methods, and a representative production method is as follows.
A monomer represented by general formula (I) or general formula (III) can be obtained by adding 1 to 100 moles of an alkylene oxide having 2 to 18 carbon atoms to an unsaturated diol having an alkenyl group having 2 to 10 carbon atoms, such as 2-(1-methylethenyl)-1,3-propanediol or 3-methylene-1,5-pentanediol, in the presence of an alkali catalyst such as potassium hydroxide or sodium hydroxide, or an acid catalyst such as boron trifluoride or tin tetrachloride.

The polymer of the present invention may further contain structural units derived from general formulas (I) and (II) and (III). By containing these structural units, a polymer with excellent water solubility can be obtained.

The polymer of the present invention can be produced by copolymerizing components essentially containing a monomer represented by general formula (I) or general formula (III) and an unsaturated carboxylic acid monomer represented by general formula (II), but the production method is not limited thereto. For example, instead of a monomer containing an unsaturated (poly)oxyalkylene chain, a monomer before the addition of alkylene oxide, i.e., an unsaturated alcohol such as 2-(1-methylethenyl)-1,3-propanediol, is used, and this is copolymerized with an unsaturated carboxylic acid monomer in the presence of a polymerization initiator, and if necessary, other monomers copolymerizable with these monomers are further copolymerized, and then an average of 1 to 200 moles of alkylene oxide are added. The copolymerization reaction can be carried out using a normal polymerization initiator, and can be carried out by a method such as polymerization in a solvent or bulk polymerization.

Polymerization in the above solvents can be carried out either continuously or batchwise. The solvents used in this case are preferably water; lower alcohols such as methanol, ethanol, and isopropyl alcohol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane, and normal hexane; ester compounds such as ethyl acetate; and ketone compounds such as acetone and methyl ethyl ketone. These may be used alone or in combination of two or more. In view of the solubility of the raw material monomers and the resulting polymer, and the solubility of the polymer during use, it is preferable to use at least one selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms.

When performing aqueous polymerization, the radical polymerization initiator may be, for example, a persulfate such as ammonium persulfate, sodium persulfate, or potassium persulfate; hydrogen peroxide; an azoamidine compound such as 2,2'-azobis-2-methylpropionamidine hydrochloride; a cyclic azoamidine compound such as 2,2'-azobis-2-(2-imidazolin-2-yl)propane hydrochloride; or a water-soluble azo-based initiator such as an azonitrile compound such as 2-carbamoylazoisobutyronitrile. In this case, an accelerator such as an alkali metal sulfite such as sodium hydrogen sulfite, a metabisulfite, sodium hypophosphite, or an Fe(II) salt such as Mohr's salt, sodium hydroxymethanesulfinate dihydrate, hydroxylamine hydrochloride, thiourea, L-ascorbic acid (salt), or erythorbic acid (salt) may also be used in combination. When hydrogen peroxide is used as a water-soluble polymerization initiator, it is preferable to use it in combination with an accelerator such as L-ascorbic acid (salt).

For polymerization using lower alcohols, aromatic hydrocarbons, aliphatic hydrocarbons, ester compounds, or ketone compounds as the solvent, peroxides such as benzoyl peroxide and lauroyl peroxide; hydroperoxides such as cumene hydroperoxide; and azo compounds such as azobisisobutyronitrile are used as polymerization initiators. In this case, accelerators such as amine compounds can also be used in combination. Furthermore, when using a water-lower alcohol mixed solvent, an appropriate polymerization initiator or combination of a polymerization initiator and an accelerator can be selected from the above-mentioned various polymerization initiators or combinations of a polymerization initiator and an accelerator. The polymerization temperature is determined appropriately depending on the solvent and polymerization initiator used, but is usually carried out at 0 to 120°C.

The bulk polymerization is carried out at a temperature of 50 to 200°C using a polymerization initiator such as a peroxide, such as benzoyl peroxide or lauroyl peroxide; a hydroperoxide, such as cumene hydroperoxide; or an azo compound, such as azobisisobutyronitrile.

The method of feeding each monomer into the reaction vessel is not particularly limited, and may be any of the following: feeding the entire amount into the reaction vessel all at once at the beginning, feeding the entire amount into the reaction vessel in portions or continuously, feeding a portion into the reaction vessel at the beginning, and feeding the remainder into the reaction vessel in portions or continuously. Specific examples of preferred feeding methods include the following methods (1) to (4).
(1) A method in which all of the monomers are continuously charged into a reaction vessel.
(2) A method in which all of the monomers containing an unsaturated (poly)oxyalkylene chain are initially charged into a reaction vessel, and all of the other monomers are continuously charged into the reaction vessel.
(3) A method in which a part of the monomer containing an unsaturated (poly)oxyalkylene chain is initially charged into a reaction vessel, and the remainder of the monomer containing an unsaturated (poly)oxyalkylene chain and all of the other monomers are continuously charged into the reaction vessel.
(4) A method in which a part of the monomer containing an unsaturated (poly)oxyalkylene chain and a part of the other monomers are initially charged into a reaction vessel, and the remaining monomer containing an unsaturated (poly)oxyalkylene chain and the remaining monomers are alternately charged into the reaction vessel in several separate portions. Furthermore, the charging rate of each monomer into the reaction vessel during the reaction may be changed continuously or stepwise to change the charging mass ratio of each monomer per unit time continuously or stepwise, thereby synthesizing a mixture of copolymers having different ratios of each structural unit in the copolymer during the polymerization reaction. The radical polymerization initiator may be charged into the reaction vessel from the beginning, or may be added dropwise to the reaction vessel, or these may be combined depending on the purpose.

A chain transfer agent can be used in combination to adjust the molecular weight of the resulting polymer. Examples of chain transfer agents include thiol-based chain transfer agents such as mercaptoethanol, thioglycerol, thioglycolic acid, 3-mercaptopropionic acid, thiomalic acid, and 2-mercaptoethanesulfonic acid; secondary alcohols such as isopropyl alcohol; and lower oxides and salts of phosphorous acid, hypophosphorous acid, and salts thereof (sodium hypophosphite, potassium hypophosphite, etc.), sulfurous acid, hydrogen sulfite, dithionous acid, metabisulfite, and salts thereof (sodium sulfite, sodium hydrogen sulfite, sodium dithionite, sodium metabisulfite, etc.). Furthermore, the use of a hydrophobic chain transfer agent is effective in improving the viscosity of the cement composition. As the hydrophobic chain transfer agent, it is preferable to use a thiol-based chain transfer agent having a hydrocarbon group with 3 or more carbon atoms, such as butanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, cyclohexyl mercaptan, thiophenol, octyl thioglycolate, and octyl 3-mercaptopropionate. Two or more types of chain transfer agents can be used in combination, and a hydrophilic chain transfer agent and a hydrophobic chain transfer agent can be used in combination. Furthermore, in order to adjust the molecular weight of the polymer, it is also effective to use a monomer with high chain transfer property, such as (meth)allylsulfonic acid (salt), as the other copolymerizable monomers described above.

In the above polymerization, in order to reproducibly obtain a polymer of a predetermined molecular weight, it is necessary to allow the polymerization reaction to proceed stably. Therefore, when carrying out solution polymerization, it is preferable to set the dissolved oxygen concentration of the solvent used at 25°C to 5 ppm or less. More preferably, it is 0.01 to 4 ppm, even more preferably 0.01 to 2 ppm, and most preferably 0.01 to 1 ppm. Note that, when nitrogen replacement or the like is carried out after adding a monomer to the solvent, it is preferable to set the dissolved oxygen concentration of the system including the monomer within the above range.

The adjustment of the dissolved oxygen concentration in the above-mentioned solvent may be carried out in a polymerization reaction tank, or a solvent in which the amount of dissolved oxygen has been adjusted in advance may be used. As a method for removing oxygen from the solvent, the following methods (1) to (5) are suitable.
(1) After filling a sealed container containing a solvent with an inert gas such as nitrogen under pressure, the pressure in the sealed container is reduced to reduce the partial pressure of oxygen in the solvent. The pressure in the sealed container may be reduced under a nitrogen stream.
(2) The gas phase in a vessel containing the solvent is replaced with an inert gas such as nitrogen while stirring the liquid phase for a long period of time.
(3) An inert gas such as nitrogen is bubbled through the solvent placed in a container for a long period of time.
(4) The solvent is boiled once and then cooled under an inert gas atmosphere such as nitrogen.
(5) A static mixer is installed in the middle of the piping, and an inert gas such as nitrogen is mixed in the piping that transports the solvent to the polymerization reaction tank.

The polymers obtained as described above can be used as they are in a cement admixture, but if necessary, they may be neutralized with an alkaline substance before use. As the alkaline substance, inorganic salts such as hydroxides and carbonates of monovalent or divalent metals, ammonia, and organic amines are suitable. In addition, after the reaction is completed, the concentration can be adjusted if necessary. In addition, instead of using an unsaturated carboxylic acid monomer (general formula (II)) as a monomer component, a copolymerization reaction can be carried out using the corresponding unsaturated carboxylic acid ester monomer, and then the ester bond portion of the constituent unit derived from the unsaturated carboxylic acid ester monomer can be partially hydrolyzed by adjusting the pH, thereby introducing a structure derived from the unsaturated carboxylic acid monomer (for example, general formula (II)) into the polymer.

[Cement admixture]
The cement admixture of the present invention has excellent water reducing performance by containing the polymer of the present invention. If necessary, it may further contain a non-polymerizable (poly)alkylene glycol having no alkenyl group, or the polymer of the present invention may be neutralized with an alkaline substance and used as a polymer salt. As such an alkaline substance, preferred examples include inorganic substances such as hydroxides, chlorides and carbonates of monovalent and divalent metals; ammonia; organic amines, etc.

When the polymer of the present invention is used as a cement admixture, the weight average molecular weight (Mw) of the polymer is preferably in the range of 500 to 500,000, particularly 5,000 to 300,000, as calculated as polystyrene by gel permeation chromatography (hereinafter referred to as "GPC"). A weight average molecular weight of less than 500 is undesirable because the water-reducing performance as a cement admixture is reduced. On the other hand, a weight average molecular weight of more than 500,000 is undesirable because the water-reducing performance and slump loss prevention performance as a cement admixture are reduced.

The polymer of the present invention can be used as a cement admixture either alone or as a mixture of two or more kinds. It can also be used in combination with other known cement admixtures, with the polymer of the present invention as the main component. Examples of such known cement admixtures include conventional cement dispersants, air entraining agents, cement wetting agents, expansive agents, waterproofing agents, retarders, quick-setting agents, water-soluble polymeric substances, thickeners, flocculants, drying shrinkage reducing agents, strength enhancers, hardening accelerators, and defoamers.

When a known cement dispersant is used, the blending mass ratio of the polymer (salt) of the present invention to the known cement dispersant, expressed as a weight ratio (weight %) converted to solid content, is preferably 1/99 to 99/1, more preferably 5/95 to 95/5, and even more preferably 10/90 to 90/10.

Examples of known cement dispersants that can be used in combination with the above include polyalkylarylsulfonate-based dispersants such as naphthalenesulfonic acid formaldehyde condensates; melamine formalin resin sulfonate-based dispersants such as melamine sulfonic acid formaldehyde condensates; aromatic aminosulfonate-based dispersants such as aminoarylsulfonic acid-phenol-formaldehyde condensates; lignin sulfonate-based dispersants such as lignin sulfonate and modified lignin sulfonate; and various sulfonic acid-based dispersants having sulfonic acid groups in the molecule, such as polystyrene sulfonate-based dispersants.

As the defoaming agent, known defoaming agents such as those exemplified in (1) and (2) below are suitable.
(1) Oxyalkylene-based defoaming agents: polyoxyalkylenes such as (poly)oxyethylene (poly)oxypropylene adducts; polyoxyalkylene alkyl ethers such as diethylene glycol heptyl ether; polyoxyalkylene acetylene ethers; (poly)oxyalkylene fatty acid esters; polyoxyalkylene sorbitan fatty acid esters; polyoxyalkylene alkyl (aryl) ether sulfates; polyoxyalkylene alkyl phosphates; polyoxypropylene polyoxyethylene laurylamine (1 to 20 moles of propylene oxide, 1 to 20 moles of ethylene oxide, etc.), amines derived from fatty acids obtained from hardened beef tallow to which alkylene oxide has been added (1 to 20 moles of propylene oxide, 1 to 20 moles of ethylene oxide, etc.), polyoxyalkylene alkylamines such as polyoxyalkylene amides, etc.
(2) Defoamers other than oxyalkylene-based ones: Defoamers based on mineral oils, oils, fatty acids, fatty acid esters, alcohols, amides, phosphates, metal soaps, silicones, and the like.

The cement admixture of the present invention can be used with hydraulic cements such as Portland cement, high-belite cement, alumina cement, and various blended cements, or with hydraulic materials other than cement, such as gypsum.

The cement admixture of the present invention can be used for various hydraulic materials, i.e., cement and hydraulic materials other than cement, such as gypsum. As hydraulic compositions containing a hydraulic material, water, and the cement admixture of the present invention, and further containing fine aggregate (sand, etc.) and coarse aggregate (crushed stone, etc.) as necessary, cement paste, mortar, concrete, and plaster are suitable.

[Cement composition]
Among the above hydraulic compositions, the most common is a cement composition using cement as the hydraulic material, and such a cement composition contains the cement admixture of the present invention, cement, and water as essential components. Such a cement composition also constitutes the present invention.

Suitable cements for use in the cement composition of the present invention include Portland cement (normal, early strength, extra early strength, moderate heat, sulfate resistant and low alkali forms of each), various blended cements (blast furnace cement, silica cement, fly ash cement), white Portland cement, alumina cement, ultra-fast hardening cement (1 clinker fast hardening cement, 2 clinker fast hardening cement, magnesium phosphate cement), cement for grouting, oil well cement, low heat cement (low heat type blast furnace cement, low heat type blast furnace cement mixed with fly ash, high belite content cement), ultra-high strength cement, cement-based solidification material, ecocement (cement manufactured using one or more of municipal waste incineration ash and sewage sludge incineration ash as raw materials), and further, fine powders such as blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, silica fume, silica powder, limestone powder, and gypsum may be added. In addition to gravel, crushed stone, granulated slag, and recycled aggregate, refractory aggregates such as silica, clay, zircon, high alumina, silicon carbide, graphite, chrome, chromium-magnesium, and magnesia can be used as aggregates.

In the cement composition of the present invention, the unit water amount per ¹ m3, the total amount of cement, fly ash and slag (hereinafter collectively referred to as "B") used, and the water/B ratio are preferably 100-185 kg/ ^m3 , 250-800 kg/ ^m3 , and 0.1-0.7 (mass ratio), and more preferably 120-175 kg/ ^m3 , 270-800 kg/ ^m3 , and 0.2-0.65 (mass ratio). This allows for a wide range of use from lean to rich mixes, and is effective for both high-strength concrete with a high unit B amount and lean concrete with a unit B amount of 300 kg/ ^m3 or less.

The mixing ratio of the cement admixture of the present invention in the cement composition of the present invention is preferably 0.01 to 5.0% based on the total mass of cement, fly ash and slag, for example, when used in mortar or concrete using hydraulic cement. This addition brings about various favorable effects such as reducing the unit water content, increasing strength and improving durability. If the mixing ratio is less than 0.01%, the performance may be insufficient, and conversely, even if a large amount exceeding 5.0% is used, the effect may substantially plateau and may be disadvantageous from an economic standpoint. More preferably, it is 0.02% or more and 2.0% or less, and even more preferably, it is 0.05% or more and 1.0% or less, and such a ratio may be added. Also, the preferred range of the mixing ratio is more preferably 0.02 to 2.0%, and even more preferably, 0.05 to 1.0%.

The cement admixture of the present invention can be used in combination with conventional cement dispersants, and can also be used in combination with multiple cement dispersants. When a conventional cement dispersant is used, the blending mass ratio of the cement admixture of the present invention to the cement dispersant cannot be uniquely determined due to differences in the type, blending, and test conditions of the cement dispersant, but is preferably 1-99/99-1, more preferably 5-95/95-5, and even more preferably 10-90/90-10.

[concrete]
The cement composition of the present invention is also effective for ready-mixed concrete, concrete for secondary concrete products (precast concrete), centrifugally molded concrete, vibration compacted concrete, steam cured concrete, shotcrete, and the like, and further is effective for mortar and concrete that require high fluidity, such as medium fluidity concrete (concrete with a slump value of 22 to 25 cm), high fluidity concrete (concrete with a slump value of 25 cm or more and a slump flow value of 50 to 70 cm), self-compacting concrete, and self-leveling material.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples in any way.

The various materials used in the Production Examples, Examples and Comparative Examples are shown below.
2-(1-methylethenyl)-1,3-propanediol: purity 91%, can be produced by the production method described in J. AM. CHEM. Soc., 104, 555 (1984), etc.
・ 3-methylene-1,5-pentanediol: 95% purity, can be produced by the production method described in WO 2018/143104.
3-Methyl-3-buten-1-ol: manufactured by Kuraray Co., Ltd., purity 98%
Ethylene oxide: manufactured by Nippon Shokubai Co., Ltd. Sodium hydroxide: manufactured by Wako Pure Chemical Industries, Ltd. Hydrogen peroxide solution: manufactured by Wako Pure Chemical Industries, Ltd. Acrylic acid: manufactured by Wako Pure Chemical Industries, Ltd. L-Ascorbic acid: manufactured by Wako Pure Chemical Industries, Ltd. 3-Mercaptopropionic acid: manufactured by Tokyo Chemical Industry Co., Ltd.

In each example, ¹ H-NMR, GPC and HPLC analyses were carried out under the following conditions.
[GPC analysis conditions]
Analytical instrument: GPC-8020 (manufactured by Tosoh Corporation)
Detector: RI-8020 (manufactured by Tosoh Corporation)
Columns used: Shodex GPC KF-802, KF-802.5, KF-803L, KF-G (guard column) (manufactured by Showa Denko K.K.)
Analysis conditions Developer: THF
Flow rate: 0.9 mL/min
Column temperature: 40°C
Sample injection volume: 30 μL
Analysis: GPC-model II (Tosoh Corporation)
[ ^1H -NMR analysis]
Analytical equipment: ULTRA SHIELD 400 PLUS (manufactured by Bruker)
Solvent: deuterated chloroform, room temperature, cumulative number of times: 120 Number of oxyalkylene groups added:
Of the produced monomers, the molar ratio was calculated from the integral ratio of each component derived from the unsaturated alcohol and the oxyalkylene group, and the number of oxyalkylenes added was calculated by converting it into a mass ratio based on the molecular weight of each component.
HPLC Analysis
Analytical equipment: Nexera X2 (Shimadzu Corporation)
Column used: Mightysil RP-18 (length 250 mm, inner diameter 4.6 mm, particle size 5 μm) (Kanto Chemical Co., Ltd.)
Detector: SPD-M30A (Shimadzu Corporation)
Developing solution: A solution of 600 g of water, 400 g of methanol, and 0.8 g of phosphoric acid. Analysis conditions: Flow rate 1.0 mL/min.
Column temperature: 40°C
Sample injection volume: 100 μL

[Production Example 1] (I-A)
A SUS high-pressure reactor equipped with a thermometer, a stirrer, nitrogen, and an ethylene oxide inlet tube was charged with 30 g of (2-(1-methylethenyl)-1,3-propanediol) as an unsaturated alcohol and 0.5 g of sodium hydroxide as a catalyst, and the atmosphere inside the reaction vessel was replaced with nitrogen while stirring, and the internal temperature was raised to 100° C. Thereafter, while maintaining the temperature at 100° C., 910 g of ethylene oxide was introduced into the reactor over 6 hours, and then heating and stirring were performed for 2 hours, after which the reaction was terminated and a monomer represented by the following formula (IA) was obtained. The measurement results of ¹ H-NMR are shown below.

^1H NMR (400MHz, _CDCl3 ) δ1.8ppm ( _CH2 =C( CH3 ₎ -), 2.6ppm ( _CH2 =C( _CH3 ) CH- ), 3.5-3.9ppm (oxyalkylene group), 4.8-4.9ppm ( C2 =C( _CH3 )-). The integral ratio of the positions _from 3.5-3.9ppm to 4.8-4.9ppm is 312. Since the oxyalkylene group has four protons and two OH chains, an average of 80 moles of ethylene oxide was added to the raw material unsaturated alcohol.

[Production Example 2] (III-A)
A monomer represented by the following formula (III-A) was obtained in the same manner as in Production Example 1, except that 30 g of 3-methylene-1,5-pentanediol was used instead of 2-(1-methylethenyl)-1,3-propanediol as the unsaturated alcohol, and that the amount of sodium hydroxide used as the catalyst was changed to 0.3 g and the amount of ethylene oxide used was changed to 600 g.

¹ H NMR (400 MHz, CDCl ₃ ) δ 2.4 ppm (CH ₂ ═C( CH ₂ ═) ₂ —), 3.5-3.9 ppm (oxyalkylene group), 4.8 ppm (C H ₂ ═C(CH ₂ ) ₂ —). The integral ratio of the positions from 3.5-3.9 ppm to 4.8 ppm is 209. Since the oxyalkylene group has four protons and two OH chains, an average of 50 moles of ethylene oxide were added to one molecule of the raw material unsaturated alcohol.

[Production Example 3]
A monomer represented by the following formula (IV-A) was obtained in the same manner as in Production Example 1, except that 50 g of 3-methyl-3-buten-1-ol was used as the unsaturated alcohol, 0.7 g of sodium hydroxide as the catalyst, and 1,304 g of ethylene oxide were used.

^1H NMR (400MHz, _CDCl3 ) δ1.8ppm ( _CH2 =C( CH3 ₎ -), 2.4ppm ( _CH2 =C( _CH3 ) CH2- ₎ , 3.5-3.9ppm (oxyalkylene group), 4.7-4.8ppm ( CH2 ₌ C( _CH2 ) _2- ). The integral ratio of the positions from 3.5-3.9ppm to 4.7-4.8ppm is 202. Since the oxyalkylene group has four protons and one OH chain, these integral ratios show that an average of 50 moles of ethylene oxide had been added to the raw material unsaturated alcohol.

The properties and water solubility of the monomers obtained in Production Examples 1 to 3 were evaluated at 25°C and 50°C. The results are shown in Table 1.

From Table 1, it can be seen that the monomers obtained in Production Example 1 or Production Example 2 dissolve more in water at 25°C than the monomers obtained in Production Example 3, and can be mixed with water in any ratio at 50°C. From these results, it can be easily inferred that the polymers using the monomers in Production Example 1 or Production Example 2 have better water solubility than the polymers using the monomers in Production Example 3 that have been used conventionally. Therefore, by using these polymers with good water solubility as cement admixtures, the amount of water used in preparing the cement admixture can be reduced, suggesting that the cement composition using this cement admixture has good volumetric efficiency and is highly productive.

Next, polymers were produced using the monomers obtained by referring to Production Examples 1, 2, and 3, and the resulting polymers were evaluated as cement admixtures. Note that, in order to keep the conditions consistent, the same amount of ion-exchanged water was used in each example.

[Example 1]
A glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser was replaced with nitrogen, 29.3 g of ion-exchanged water and 98.7 g of the monomer obtained in Production Example 1 were charged, and the temperature was raised to 60°C. 4.8 g of a 4% aqueous hydrogen peroxide solution was added thereto. Next, an aqueous solution in which 8.2 g of acrylic acid was diluted with 1.6 g of ion-exchanged water was dropped over 4 hours. At the same time, an aqueous solution in which 0.12 g of L-ascorbic acid and 0.12 g of 3-mercaptopropionic acid were dissolved in 31.8 g of ion-exchanged water was dropped over 4.5 hours. After the dropwise addition, stirring was continued for 1 hour to terminate the polymerization reaction. Thereafter, the reaction solution was neutralized to pH 6.5 using a 30% aqueous sodium hydroxide solution at a temperature below the polymerization reaction temperature, and an aqueous solution of a polycarboxylic acid copolymer having a weight average molecular weight (Mw) of 30,000 was obtained. HPLC analysis revealed that the monomer conversion was 47% and the acrylic acid conversion was 99.9% or more. The aqueous solution was adjusted to an active ingredient concentration of 10.0% by adding dilution water.
Here, the above-mentioned active ingredient concentration is a value obtained by multiplying the active ingredient ratio calculated using the reactivity of the unsaturated carboxylic acid monomer, which is a polymerizable monomer, and the monomer of the production example by the solid content, and is a value defined by the following formula. The amount of the monomer used below is the amount of each monomer used during polymerization. The solid content is the amount obtained by distilling under reduced pressure and drying the aqueous solution of the polycarboxylic acid copolymer obtained in the examples.
Active ingredient concentration = [(a + b) / (A + B)] x NV
The abbreviations in the above formula are as follows.
A: Amount of unsaturated carboxylic acid monomer used B: Amount of monomer used in the production example a: Amount of unsaturated carboxylic acid monomer used x conversion b: Amount of monomer used in the production example x conversion NV: Solid content

[Example 2]
An aqueous solution of a polycarboxylic acid copolymer having a weight average molecular weight (Mw) of 26,700 was obtained in the same manner as in Example 1, except that 98.7 g of a monomer in which an average of 100 moles of ethylene oxide was added to 1 mole of 2-(1-methylethenyl)-1,3-propanediol (i.e., a monomer containing twice the amount of ethylene oxide as compared with the monomer in Production Example 2) was used instead of 98.7 g of the monomer obtained in Production Example 1. HPLC analysis showed that the monomer conversion rate was 49% and the acrylic acid conversion rate was 99.9% or more. The obtained aqueous solution was adjusted by adding dilution water so that the active ingredient concentration was 10.0%.

[Comparative Example 1]
An aqueous solution of a polycarboxylic acid copolymer having a weight average molecular weight (Mw) of 25,500 was obtained in the same manner as in Example 1, except that 98.7 g of the monomer obtained in Production Example 3 was used instead of 98.7 g of the monomer obtained in Production Example 1. HPLC analysis showed that the monomer conversion rate was 58% and the acrylic acid conversion rate was 99.9% or more. The aqueous solution obtained was adjusted by adding dilution water so that the active ingredient concentration was 10.0%.

Next, a cement admixture (Ad) was prepared using the aqueous solutions of the copolymers produced in Examples 1 and 2 and Comparative Example 1, and the physical properties of the cement using this cement admixture were measured.

Cement (C) was ordinary Portland cement (density 3.16 g/cm ³ ) manufactured by Taiheiyo Cement Corporation. Fine aggregate (S) was land sand from the Oi River water system in Shizuoka Prefecture (surface dry density 2.66 g/cm ³ ). Coarse aggregate (G) was sandstone crushed stone 2005 (surface dry density 2.66 g/cm ³ ) from Ome City, Tokyo. Mixing water (W) was water from Chigasaki City, Kanagawa Prefecture. The aggregate used in the test was adjusted so that the surface water rate of the fine aggregate was 1% or less and the coarse aggregate was in a surface dry water-saturated state. All materials used were stored in a constant temperature and humidity room at 20°C and taken out immediately before use. Slump flow was measured according to JIS A 1150:2014 "Test method for slump flow of concrete". Slump was measured according to JIS A 1101:2014 "Test method for slump flow of concrete".
The concrete was mixed using a forced mixing mixer pan type with a capacity of 55 L, according to the procedure shown below. The amount of concrete mixed was 30 L.
Add fine aggregate (half the amount), cement, and fine aggregate (half the amount), mix for 10 seconds, add water and admixture, mix for 30 seconds, scrape off, add coarse aggregate, mix for another 90 seconds, then discharge and measure.

The concrete mix ratio is shown below.

The retention rate, defined as the flow value after 60 minutes divided by the flow value at the initial time 0 minutes, was used as an index, and the retention was evaluated according to the following evaluation criteria. A higher retention rate value means better retention.
Retention Evaluation Criteria Evaluation A: Retention rate is 50% or more Evaluation X: Retention rate is 25% or more but less than 50%

It can be seen that Examples 3 and 4 show higher flow retention rates than Comparative Example 2, which is a conventional cement admixture.

Claims (7)

A polymer comprising a structural unit derived from general formula (II) and a structural unit derived from the following general formula (III):
[In general formula (II), R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom or a methyl group, and M represents at least one selected from the group consisting of a hydrogen atom, a monovalent metal atom, a divalent metal atom and ammonium.]
[In general formula (III), ^R8 and ^R9 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, _Rb and _Rc each independently represent an alkylene group having 2 to 18 carbon atoms, l represents an integer of 0 to 4, and m represents an integer of 1 to 200.] The polymer according to claim 1, wherein in general formula (II), M is at least one selected from the group consisting of a hydrogen atom, a monovalent metal atom, and a divalent metal atom. 3. The polymer according to claim 1, wherein in the general formula (III), ^R8 and ^R9 are hydrogen atoms, _Rb and _Rc are ethylene groups, and l is 2. A cement admixture comprising the polymer according to any one of claims 1 to 3. A cement composition comprising the cement admixture according to claim 4. Concrete obtained by hardening the cement composition according to claim 5. A compound represented by the following general formula (V):
[In general formula (V), R _b and R _c each independently represent an alkylene group having 2 to 18 carbon atoms, l represents an integer of 0 to 4, and m represents an integer of 1 to 200.]