JP7457491B2 - Cement admixture composition for precasting - Google Patents

Description

The present invention relates to a cement admixture composition for precasting. More specifically, the present invention relates to a precast cement admixture composition that can be suitably used in cement compositions and the like.

Polycarboxylic acid copolymers containing polyalkylene glycol in the side chains of polycarboxylic acids such as poly(meth)acrylic acid are used in cement compositions such as cement paste, mortar, and concrete, as well as in civil engineering, due to their excellent cement dispersion performance.・It is indispensable for constructing architectural structures, etc.
Cement admixtures containing such copolymers are used as water reducing agents, etc., and have the effect of improving the strength and durability of cured products by increasing the fluidity of the cement composition and reducing the water content of the cement composition. will have the following. Conventionally, naphthalene-based water-reducing agents have been used, but compared to these, cement additives based on copolymers such as polycarboxylic acid-based copolymers exhibit higher water-reducing performance. Because of this, it has been widely used as a high-performance AE water reducing agent.

As a cement admixture containing such a copolymer, for example, Patent Document 1 describes (1) a cement admixture in which a polyalkylene glycol monoester monomer and an acrylic acid monomer and/or an unsaturated dicarboxylic acid monomer are polymerized. The obtained copolymer and/or its metal salt, (2) polyethylene glycol having a weight average molecular weight of 5,000 to 100,000, and (3) one or two selected from the group consisting of oxycarboxylic acid or its salt, sugar, and sugar alcohol. An admixture for ultra-high strength concrete has been disclosed which contains the three above-mentioned compounds as essential components. Patent Documents 2 to 4 also disclose cement admixtures containing polycarboxylic acid copolymers.

By the way, unlike the cast-in-place construction method in which formwork is installed at the construction site of a concrete structure and concrete is poured, the basic components of a concrete structure are manufactured in a factory and then brought to the site and the frame is assembled. The precast construction method has advantages such as shortening the construction period and reducing labor costs.

Japanese Patent Application Publication No. 6-092704 JP 2017-160077 Publication JP2003-212622A Japanese Patent Application Publication No. 9-241055

In the precast construction method, concrete is generally placed in a formwork, cured using a method called steam curing in which the concrete is exposed to high temperature and constant humidity, and then removed from the formwork. In the precast method, early strength development of concrete is required in order to shorten the time until demolding. As mentioned above, although various cement admixtures have been disclosed in the past, they are not sufficient in terms of the early strength development required for precast construction methods, but they are capable of developing cement strength earlier than conventional cement admixtures. There was room to develop cement admixtures.

The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a cement admixture composition for precasting that can develop cement strength earlier than conventional cement admixtures.

The present inventor conducted various studies on cement admixtures and found that a copolymer having a structural unit derived from an unsaturated carboxylic acid monomer and a structural unit derived from a (poly)alkylene glycol monomer, a hydroxyl group, and a compound having two or more functional groups selected from the group consisting of a carboxyl group, an amino group, a sulfonic acid group, a phosphoric acid group, a phosphorous acid group, and a salt group thereof, and having a molecular weight of 1000 or less. We have discovered that a cement admixture composition containing a specific proportion of the following compounds can quickly develop excellent cement strength, and have come up with the present invention. be.

That is, the present invention provides a copolymer (a) having a structural unit (a1) derived from an unsaturated carboxylic acid monomer (A1) and a structural unit (a2) derived from a (poly)alkylene glycol monomer (A2). α), a hydroxyl group, and two or more functional groups selected from the group consisting of a carboxyl group, an amino group, a sulfonic acid group, a phosphoric acid group, a phosphorous acid group, and a salt group thereof, and the molecular weight is 1000 or less, and the content of the compound (β) is 0.1 to 7% by mass based on 100% by mass of the copolymer (α). It is.

The compound (β) preferably has a hydroxyl group.

The compound (β) preferably has a carboxyl group and/or a salt group thereof.

The compound (β) preferably has a hydroxyl group, a carboxyl group, and/or a salt group thereof.

The compound (β) preferably has two or more hydroxyl groups.

The compound (β) preferably contains at least one selected from the group consisting of saccharides; monosaccharide oxides and salts thereof; and oxycarboxylic acids other than the derivatives and salts thereof.

The compound (β) preferably contains an aldonic acid (salt).

（式中、Ｒ^１、Ｒ^２及びＲ^３は、同一又は異なって、水素原子、又は、メチル基を表す。Ｒ^４は、水素原子、又は、炭素数１～３０の炭化水素基を表す。（Ｒ^５Ｏ）は、同一又は異なって、オキシアルキレン基を表す。ｎは、オキシアルキレン基の平均付加モル数を表し、１～３００の数である。ｘは、０～４の数を表す。ｙは、０又は１を表す。）で表されることが好ましい The above (poly)alkylene glycol monomer (A2) has the following formula (1);

(In the formula, R ¹ , R ² and R ³ are the same or different and represent a hydrogen atom or a methyl group. R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. (R ⁵ O) are the same or different and represent an oxyalkylene group. n represents the average number of added moles of the oxyalkylene group and is a number from 1 to 300. x represents a number from 0 to 4. .y represents 0 or 1).

In the (poly)alkylene glycol monomer (A2), it is preferable that y in the above formula (1) is 0.

The present invention also provides a precast cement composition comprising the above precast cement admixture composition and cement.

The present invention further provides a method for producing a cured cement product, which includes the steps of mixing the cement admixture composition for precasting with cement, and curing the composition obtained in the mixing step at 15 to 90°C. .

In the above manufacturing method, it is preferable that the curing process is carried out under humidity conditions of 40 to 100%.

In the manufacturing method, the curing step is preferably performed by steam curing.

In the above manufacturing method, the curing step is preferably carried out for 1 to 10 hours.

The present invention also relates to a method for hardening cement, which comprises hardening a composition containing the above precast cement admixture composition and cement at 40 to 90°C.

The precast cement composition of the present invention has the above-described structure and can develop cement strength earlier than conventional cement admixtures, so it can be suitably used for precast cement compositions and the like.

Preferred embodiments of the present invention will be specifically described below, but the present invention is not limited to the following description, and can be applied with appropriate modifications within the scope of the gist of the present invention. Note that combinations of two or more of the individual preferred embodiments of the present invention described below also correspond to preferred embodiments of the present invention.

[Cement admixture composition for precasting]
The precast cement admixture composition of the present invention contains the above copolymer (α) and the above compound (β), and the content of the compound (β) is based on 100% by mass of the copolymer (α). It is 0.1 to 7% by mass.
The compound (β) has a hydroxyl group, and two or more functional groups selected from the group consisting of a carboxyl group, an amino group, a sulfonic acid group, a phosphoric acid group, a phosphorous acid group, and a salt group thereof. , the molecular weight is 1000 or less.
By including such a compound (β), complexes can be formed with calcium ions, silicate ions, etc. in the cement by the above two or more functional groups, and the estimation of (1) or (2) below can be achieved. It is thought that this mechanism can improve cement strength.
(1) It is thought that the compound (β) changes the crystal structure by adsorbing to the crystal nuclei of cement, and coarsens the density of the crystals generated in the initial stage of the hydration reaction (from about 1 hour after water injection). As a result, since the crystals present on the cement particle surface are coarse, water can come into contact with the cement surface even at the final stage of the hydration reaction, ion elution is not inhibited, the hydration reaction progresses sufficiently, and the cement strength increases. It is thought that this will improve.
(2) By adsorbing the compound (β) to the crystal nuclei of cement, the crystal growth rate at the initial stage of the hydration reaction is slowed down, the voids between the formed crystals are reduced, and the formed crystals become denser. It is thought that the coarse voids that become weak parts are reduced and the cement strength is improved.
Furthermore, by setting the content of the compound (β) within the above specific range, cement strength can be developed at an early stage.
The content of the compound (β) is 0.1 to 7% by mass, more preferably 0.5 to 7% by mass, and even more preferably 2 to 6% by mass based on 100% by mass of the copolymer (α). %, most preferably 3 to 6% by weight.

The content of the copolymer (α) in the cement admixture composition for precasting is preferably 50 to 99.9% by mass based on 100% by mass of the total composition. The content is more preferably 70 to 99% by mass, and even more preferably 90 to 98% by mass.

The above-mentioned cement admixture composition for precasting may contain other components other than the above-mentioned copolymer (α) and compound (β), and the total content thereof is based on 100% by mass of the total amount of the composition. It is preferably 0 to 10% by mass. It is more preferably 0 to 5% by weight, still more preferably 0 to 1% by weight, and most preferably 0% by weight.
The other components mentioned above are not particularly limited, but include other additives described below.

<Copolymer (α)>
The copolymer (α) has a structural unit (a1) derived from an unsaturated carboxylic acid monomer (A1) and a structural unit (a2) derived from a (poly)alkylene glycol monomer (A2). .

In the copolymer (α), the proportion of the structural unit (a1) is preferably 1 to 40% by mass based on 100% by mass of all structural units. It is more preferably 3 to 30% by weight, still more preferably 5 to 25% by weight, and most preferably 10 to 20% by weight. In addition, in the present invention, when calculating the mass ratio (mass %) of the structural unit (a1) to 100 mass % of all structural units, the calculation is performed in terms of the corresponding sodium salt. For example, the mass proportion of the structural unit derived from acrylic acid is calculated as the mass proportion (mass %) of the structural unit derived from the corresponding sodium salt, sodium acrylate.

In the copolymer (α), the proportion of the structural unit (a2) is preferably 60 to 99% by mass based on 100% by mass of all structural units. It is more preferably 70 to 97% by weight, still more preferably 75 to 95% by weight, and most preferably 80 to 90% by weight.

The copolymer (α) has a structural unit (a3) derived from a monomer (A3) other than the unsaturated carboxylic acid monomer (A1) and the (poly)alkylene glycol monomer (A2). It may have.
The proportion of the structural unit (a3) in the copolymer is preferably 0 to 10% by mass based on 100% by mass of all structural units. It is more preferably 0 to 8% by weight, still more preferably 0 to 5% by weight, and most preferably 0% by weight.

The copolymer (α) preferably has a weight average molecular weight of 5,000 to 100,000. It is more preferably 10,000 to 70,000, still more preferably 20,000 to 50,000, particularly preferably 25,000 to 40,000.
The weight average molecular weight can be measured by the method described in Examples.

The unsaturated carboxylic acid monomer (A1) (hereinafter also referred to as monomer (A1)) is not particularly limited as long as it has an unsaturated hydrocarbon group and at least one carboxyl group, but for example, , (meth)acrylic acid, crotonic acid, isocrotonic acid, tiglic acid, 3-methylcrotonic acid, 2-methyl-2-pentenoic acid, α-hydroxyacrylic acid, and other unsaturated monocarboxylic acids or salts thereof; fumaric acid , maleic acid, itaconic acid, citraconic acid and other unsaturated dicarboxylic acids having 4 to 6 carbon atoms, or salts thereof; half esters of the above-mentioned unsaturated dicarboxylic acids and alcohols having 1 to 30 carbon atoms, described below; Examples include half-amides with amines of 30 and the like.

The above-mentioned salt is preferably a metal salt, an ammonium salt, an organic amine salt, or the like. Examples of metal atoms forming metal salts include monovalent metal atoms such as alkali metal atoms such as lithium, sodium, and potassium; divalent metal atoms such as alkaline earth metal atoms such as calcium and magnesium; aluminum; Trivalent metal atoms such as iron are preferred, and as the organic amine salts, alkanolamine salts such as ethanolamine salts, diethanolamine salts, triethanolamine salts, and triethylamine salts are preferred.
The above salt is preferably an alkali metal salt, more preferably a sodium salt.

Examples of the alcohol having 1 to 30 carbon atoms include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1- Aliphatic alcohols such as hexanol, 2-hexanol, 3-hexanol, octanol, 2-ethyl-1-hexanol, nonyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol; Alicyclic alcohols such as cyclohexanol; ) Allyl alcohol, 3-buten-1-ol, 3-methyl-3-buten-1-ol, and other unsaturated alcohols.
Examples of the amine having 1 to 30 carbon atoms include aliphatic amines such as methylamine, dimethylamine, ethylamine, diethylamine, propylamine, dipropylamine, butylamine, dibutylamine, isopropylamine, and diisopropylamine.

The unsaturated carboxylic acid monomer (A1) is preferably the unsaturated monocarboxylic acids mentioned above. When unsaturated monocarboxylic acids are used in the polymerization reaction, there is an advantage that the polymerization rate with monomer (A2) can be improved, and the amount of polymer in the additive can be increased. More preferred as the unsaturated carboxylic acid monomer (A1) are acrylic acid, methacrylic acid, and salts thereof.

The above (poly)alkylene glycol monomer (A2) (hereinafter also referred to as monomer (A2)) is a compound represented by the above formula (1).
In the above formula (1), R ¹ to R ³ are the same or different and represent a hydrogen atom or a methyl group. Preferably, R ¹ and R ² are hydrogen atoms, and R ³ is a hydrogen atom or a methyl group. More preferably, R ¹ and R ² are hydrogen atoms, and R ³ is a methyl group.

R ⁴ in the above formula (1) represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. Preferably a hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom, more preferably a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms, even more preferably a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. , particularly preferably a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, most preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms.
Examples of hydrocarbon groups include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, 3-pentyl group, Hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, isooctyl group, 2,3,5-trimethylhexyl group, 4-ethyl-5-methyloctyl group and 2-ethylhexyl group, tetradecyl group linear or branched alkyl groups such as octadecyl, icosyl; cyclic alkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl; phenyl, benzyl, phenethyl, o- , m- or p-tolyl group, 2,3- or 2,4-xylyl group, mesityl group, naphthyl group, anthryl group, phenanthryl group, biphenylyl group, benzhydryl group, trityl group, pyrenyl group, etc. Can be mentioned. Among these, straight chain, branched chain or cyclic alkyl groups are preferred.

In the above formula (1), R ⁵ O is “same or different” and represents an oxyalkylene group having 2 to 18 carbon ^atoms ; This means that the groups may all be the same or different.
The oxyalkylene group preferably has 2 to 18 carbon atoms. More preferably 2 to 12, still more preferably 2 to 8, particularly preferably 2 to 4.
In the above formula (1), the oxyalkylene group represented by R ⁵ O is an alkylene oxide adduct, and examples of such alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, isobutylene oxide, 1-butene oxide, Examples include alkylene oxides having 2 to 8 carbon atoms such as 2-butene oxide and styrene oxide. More preferred are alkylene oxides having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, and butylene oxide, and even more preferred are ethylene oxide and propylene oxide.
In addition, when the above polyalkylene glycol is an adduct of two or more arbitrary alkylene oxides selected from ethylene oxide, propylene oxide, butylene oxide, styrene oxide, etc., any of random addition, block addition, alternating addition, etc. It may be a form. In addition, in order to ensure a balance between hydrophilicity and hydrophobicity, it is preferable that the oxyalkylene group in the polyalkylene glycol has an oxyethylene group as an essential component, and it is more preferable that 50 mol% or more is an oxyethylene group. It is more preferable that 90 mol% or more of the oxyethylene groups are oxyethylene groups.

In the above formula (1), n represents the average number of added moles of oxyalkylene groups, and is 1 to 300. n is preferably 5 to 250, more preferably 10 to 200, even more preferably 20 to 150, particularly preferably 50 to 100.

In the above formula (1), x represents a number from 0 to 4, and y represents 0 or 1.
Preferably, x is 1-4. Preferably, y is 0. Since the monomer (A2) in which y is 0 is inexpensive, the polycarboxylic acid copolymer of the present invention can be produced at low cost.
When y is 0, x is preferably 1 to 4, more preferably 1 or 2, and even more preferably 2. When x is 1 to 4, R ³ is preferably a methyl group.
When y is 1, x is preferably 0. In this case, R ³ is more preferably a hydrogen atom or a methyl group.

Specific examples of the monomer (A2) include (poly)alkylene glycol (meth)acrylates such as polyethylene glycol (meth)acrylate and alkoxy (poly)alkylene glycol (meth)acrylates whose ends are hydrophobically modified with a hydrocarbon group having 1 to 30 carbon atoms; vinyl alcohol, allyl alcohol, methallyl alcohol, 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-3-buten-1-ol, 2-methyl-2-buten-1-ol, 3-allyloxy-1,2-propanediol, and other unsaturated alcohols having 2 to 8 carbon atoms, with 1 to 300 moles of alkylene oxide added thereto, and compounds whose ends are hydrophobically modified with a hydrocarbon group having 1 to 30 carbon atoms. Among these, compounds whose ends are hydrophobically modified with a hydrocarbon group having 1 to 30 carbon atoms and compounds whose ends are hydrophobically modified with a hydrocarbon group having 1 to 30 carbon atoms are preferred. More preferably, it is a compound in which 1 to 300 moles of alkylene oxide are added to an unsaturated alcohol having 2 to 8 carbon atoms, and even more preferably, it is a compound in which an alkylene oxide is added to methallyl alcohol or 3-methyl-3-buten-1-ol.

The copolymer (α) may have a structural unit (a3) derived from a monomer (A3) other than the monomers (A1) and (A2).
Other monomers (A3) are not particularly limited as long as they can be copolymerized with monomers (A1) and (A2), but examples include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, etc. Hydroxyalkyl (meth)acrylates; Esters of unsaturated monocarboxylic acids such as methyl (meth)acrylate and glycidyl (meth)acrylate with alcohols having 1 to 30 carbon atoms; (anhydrous) maleic acid, fumaric acid, itacon Diesters of unsaturated dicarboxylic acids such as acids and alcohols having 1 to 30 carbon atoms; Diamides of the above unsaturated dicarboxylic acids and amines having 1 to 30 carbon atoms; Diesters of alkyl (poly)alkylene glycols with 1 to 500 moles of alkylene oxide of No. 18 added thereto and the above unsaturated dicarboxylic acids; addition moles of the above unsaturated dicarboxylic acids and glycols having 2 to 18 carbon atoms or these glycols Number 2 to 500 polyalkylene glycols and diesters; (poly)alkylene glycol di(meth)acrylates such as (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate; hexane diol di(meth)acrylates; Polyfunctional (meth)acrylates such as (meth)acrylate and trimethylolpropane tri(meth)acrylate. (Poly)alkylene glycol dimalates such as polyethylene glycol dimalate; unsaturated sulfonic acids (salts) such as vinyl sulfonate, (meth)allylsulfonate, 2-methylpropanesulfonic acid (meth)acrylamide, and styrene sulfonic acid; methyl Amides of unsaturated monocarboxylic acids such as (meth)acrylamide and amines having 1 to 30 carbon atoms; Vinyl aromatics such as styrene, α-methylstyrene, and vinyltoluene; 1,4-butanediol mono(meth) ) acrylates and other alkanediol mono(meth)acrylates; dienes such as butadiene and isoprene; Saturated amides; unsaturated cyanogens such as (meth)acrylonitrile; unsaturated esters such as vinyl acetate; unsaturated amines such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and vinylpyridine; Divinyl aromatics such as divinylbenzene; allyls such as (meth)allyl alcohol and glycidyl (meth)allyl ether; vinyl ethers such as (methoxy)polyethylene glycol monovinyl ether and (methoxy)polyethylene glycol mono(meth)allyl ether; Examples include meth)allyl ethers and the like.

The method for producing the copolymer (α) of the present invention is not particularly limited, but it can be produced by polymerizing the monomer components, and specific and preferred examples of the monomer components are as described above. The content ratio of each monomer component relative to 100% by mass of all monomer components is the same as the content ratio of structural units (a1) to (a3) relative to 100% by mass of all structural units described above.

In producing the above copolymer, a chain transfer agent can be used 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; Phosphoric acid, hypophosphorous acid and its salts (sodium hypophosphite, potassium hypophosphite, etc.), sulfurous acid, hydrogen sulfite, dithionite, metabisulfite and its salts (sodium sulfite, sodium hydrogen sulfite, Examples include hydrophilic chain transfer agents such as lower oxides (sodium dithionate, sodium metabisulfite, etc.) and salts thereof.

As the chain transfer agent, a hydrophobic chain transfer agent can also be used. As the hydrophobic chain transfer agent, for example, a thiol-based chain transfer agent having a hydrocarbon group having 3 or more carbon atoms, such as butanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, cyclohexyl mercaptan, thiophenol, octyl thioglycolate, or octyl 3-mercaptopropionate, is preferably used.
In order to adjust the molecular weight of the copolymer, it is also effective to use, as the monomer (E), a monomer having high chain transfer property, such as (meth)allylsulfonic acid (salts).

The amount of the chain transfer agent to be used may be set as appropriate, but is preferably 0.1 mol or more, more preferably 0.25 mol or more, still more preferably 0.5 mol or more, based on 100 mol of the total amount of monomer components. The amount is preferably at most 20 moles, more preferably at most 15 moles, even more preferably at most 10 moles.

The above polymerization reaction can be carried out by a method such as solution polymerization or bulk polymerization, using a radical polymerization initiator if necessary. Solution polymerization can be carried out batchwise, continuously, or in a combination thereof, and the solvents used at that time include, for example, water; alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; benzene, toluene, Examples include aromatic or aliphatic hydrocarbons such as xylene, cyclohexane, and n-hexane; ester compounds such as ethyl acetate; ketone compounds such as acetone and methyl ethyl ketone; and cyclic ether compounds such as tetrahydrofuran and dioxane. Among these, it is preferable to carry out polymerization by an aqueous solution polymerization method.

When carrying out the above aqueous solution polymerization, as a radical polymerization initiator, water-soluble polymerization initiators such as persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate; hydrogen peroxide; 2,2'-azobis- Azoamidine compounds such as 2-methylpropionamidine hydrochloride, cyclic azoamidine compounds such as 2,2'-azobis-2-(2-imidazolin-2-yl)propane hydrochloride, azonitrile such as 2-carbamoylazoisobutyronitrile Water-soluble azo initiators such as compounds are used, and in this case, alkali metal sulfites such as sodium bisulfite, metabisulfite, sodium hypophosphite, Fe(II) salts such as Mohr's salt, hydroxymethanesulfine, etc. Accelerators such as acid sodium dihydrate, hydroxylamine hydrochloride, thiourea, L-ascorbic acid (salt), and erythorbic acid (salt) can also be used in combination. Among these, combinations of persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, hydrogen peroxide, and accelerators such as L-ascorbic acid (salt) are preferred. These radical polymerization initiators and accelerators may be used alone, or two or more types may be used in combination.
In addition, when performing solution polymerization using a lower alcohol, aromatic or aliphatic hydrocarbon, ester compound, or ketone compound as a solvent, or when performing bulk polymerization, benzoyl peroxide, lauroyl peroxide, sodium peroxide, etc. Hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide; azo compounds such as azobisisobutyronitrile, and the like are used as radical polymerization initiators. At this time, a promoter such as an amine compound can also be used in combination. Furthermore, when a water-lower alcohol mixed solvent is used, it can be appropriately selected from among the various radical polymerization initiators or combinations of radical polymerization initiators and accelerators described above.

The amount of the radical polymerization initiator used is preferably 0.001 mol or more, more preferably 0.01 mol or more, even more preferably 0.1 mol or more, and particularly preferably 0.2 mol or more, per 100 mol of the total amount of the monomer components, and is preferably 20 mol or less, even more preferably 10 mol or less, particularly preferably 5 mol or less, and most preferably 3 mol or less.

In the above polymerization reaction, polymerization conditions such as polymerization temperature are appropriately determined depending on the polymerization method, solvent, polymerization initiator, and chain transfer agent used, but the polymerization temperature is preferably 0°C or higher, and The temperature is preferably 150°C or lower. The temperature is more preferably 30°C or higher, and even more preferably 50°C or higher. Further, the temperature is more preferably 120°C or lower, and still more preferably 100°C or lower.

The method of feeding each monomer component into the reaction vessel is not particularly limited, and examples thereof include a method of feeding the entire amount into the reaction vessel at once at the beginning; a method of feeding the entire amount into the reaction vessel in portions or continuously; a method of feeding a part of the monomer component into the reaction vessel at the beginning and feeding the remainder into the reaction vessel in portions or continuously. In addition, the feeding rate of each monomer into the reaction vessel may be changed continuously or stepwise during the reaction to change the feeding weight ratio of each monomer per unit time continuously or stepwise, thereby synthesizing two or more copolymers having different monomer ratios simultaneously during the polymerization reaction. The radical polymerization initiator may be charged into the reaction vessel from the beginning, may be added dropwise to the reaction vessel, or may be combined depending on the purpose.
The polymers obtained as described above can be used as dispersants as they are, but if necessary, they may be neutralized with an alkaline substance. Suitable alkaline substances include inorganic salts such as hydroxides and carbonates of monovalent or divalent metals, ammonia, and organic amines. After the reaction is completed, the concentration can be adjusted if necessary.

<Compound (β)>
The compound (β) contained in the precast cement admixture composition of the present invention has a hydroxyl group and two or more functional groups selected from the group consisting of a carboxyl group, an amino group, a sulfonic acid group, a phosphoric acid group, a phosphorous acid group, and salts thereof, and has a molecular weight of 1,000 or less.
Examples of the salt of the acid group include the salts described above for the unsaturated carboxylic acid monomer (A1).
Examples of the salt of the amino group include neutralization products with acids such as hydrochloric acid and acetic acid; ammonium bases with alkyl halides such as methyl chloride, ethyl chloride, methyl bromide and methyl iodide; and ammonium bases with common alkylating agents such as alkyl sulfates such as dimethyl sulfate, diethyl sulfate and di-n-propyl sulfate.

The compound (β) may be one having two or more of the above functional groups, but compounds having two or more hydroxyl groups, compounds having a hydroxyl group and a carboxyl group or a salt group thereof, and a hydroxyl group and an amino group may be used as the compound (β). Compounds having two or more carboxyl groups or salts thereof, compounds having two or more amino groups or salts thereof, compounds having two or more sulfonic acid groups or salts thereof, hydroxyl groups and sulfonic acid or a salt group thereof, a compound having two or more phosphoric acid groups or a salt group thereof, etc., and at least one of these can be used.
Specific examples of these compounds are shown below, but as long as the compound (β) has two or more of the above functional groups and has a molecular weight of 1000 or less, it may fall under two or more categories of compounds, such as The compound may be a compound having two or more hydroxyl groups, or a compound having a hydroxyl group and a carboxyl group or a salt group thereof.

Examples of the compound having two or more hydroxyl groups include saccharides, polyols other than saccharides, oxocarbon acids, and the like.
Examples of the above sugars include hexoses such as glucose, mannose, galactose, fructose, sorbose, and tagatose; pentoses such as arabinose, xylose, ribose, xylulose, and ribulose; Examples include saccharides, and isomers thereof may also be used. Among them, glucose, sucrose, trehalose, xylose, sorbose, etc. are preferred.

Polyols other than the above sugars include sugar alcohols with 3 to 12 carbon atoms such as glycerin, erythritol, threitol, arabinitol, xylitol, ribitol, iditol, galactitol, sorbitol, mannitol, boremitol, isomalt; trimethylolethane, trimethylol Trivalent or higher aliphatic alcohols with 3 to 12 carbon atoms other than sugar alcohols such as propane, pentaerythritol, sorbitan, diglycerin; ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4- Divalent fats with 2 to 12 carbon atoms such as butanediol, 1,6-hexanediol, octanediol, decanediol, dodecanediol, tetradecanediol, neopentyl glycol, and 2,2-diethyl-1,3-propanediol Group alcohols; aromatic polyhydric alcohols having 6 to 12 carbon atoms such as catechol and resorcinol; (poly)ether polyols such as diethylene glycol, polyethylene glycol, and tetrahydroxy di-n-propyl ether; esters of trivalent or higher polyols such as monoacetin Examples include chemical substances.

Examples of the oxocarbon acids include delta acid (triangular acid), squaric acid (square acid), croconic acid (pentagonal acid), rhodizonic acid (hexagonal acid), heptagonic acid (heptagonic acid), and the like.

Examples of the compound having the above-mentioned hydroxyl group and carboxyl group or a salt group thereof include derivatives obtained by oxidizing the above-mentioned monosaccharides (monosaccharide oxides), oxycarboxylic acids other than the above-mentioned oxides, and salts thereof. .
Examples of the monosaccharide oxides include aldonic acid, aldaric acid, uronic acid, and the like. Among them, aldonic acid is preferred.

The above-mentioned aldonic acid is a sugar acid obtained by oxidizing the aldehyde functional group of aldose to form a carboxylic acid functional group, and specific examples thereof include glyceric acid, xylonic acid, gluconic acid, and ascorbic acid. , these isomers may be used. Among them, gluconic acid is preferred.

The above-mentioned aldaric acid is a sugar acid in which both terminals of aldose are oxidized, and specific examples thereof include tartaric acid, mesogalactaric acid, D-glucaric acid, etc., and may be isomers thereof. Among these, tartaric acid is preferred.

The above-mentioned uronic acid is a sugar acid in which the terminal hydroxyl group of an aldose or ketose is oxidized, and specific examples thereof include glucuronic acid, galacturonic acid, iduronic acid, and the like, and may be isomers thereof.

Examples of the oxycarboxylic acids other than the oxides of monosaccharides include aliphatic oxycarboxylic acids having 2 to 18 carbon atoms and aromatic oxycarboxylic acids having 6 to 12 carbon atoms.
The above aliphatic oxycarboxylic acids having 2 to 18 carbon atoms are not particularly limited, but include, for example, glucoheptonic acid, glycolic acid, hydroxypropionic acid, hydroxybutanoic acid, hydroxypentanoic acid, hydroxyhexanoic acid, hydroxyheptanoic acid, Hydroxynonanoic acid, hydroxydecanoic acid, hydroxyundecanoic acid, hydroxydodecanoic acid, hydroxytridecanoic acid, hydroxytetradecanoic acid, hydroxypentadecanoic acid, hydroxyhexadecanoic acid, hydroxyheptadecanoic acid, hydroxyoctadecanoic acid, hydroxynonadecanoic acid, hydroxyicosane Acid, hydroxydocosanoic acid, hydroxytetradocosanoic acid, hydroxyhexadocosanoic acid, hydroxyoctadocosanoic acid, lactic acid, tartronic acid, hydroxybutyric acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, γ-hydroxybutyric acid, malic acid , citramaric acid, citric acid, isocitric acid, leucinic acid, mevalonic acid, pantoic acid, ricinoleic acid, ricinelaidic acid, cerebronic acid, quinic acid, shikimic acid, tartaric acid, etc., and isomers thereof may also be used. The number of carbon atoms in the aliphatic oxycarboxylic acid is preferably 3 to 6. Preferred aliphatic oxycarboxylic acids include malic acid, citric acid, and glucoheptonic acid.

The aromatic oxycarboxylic acid having 6 to 12 carbon atoms is not particularly limited, but examples include monohydroxybenzoic acid derivatives such as salicylic acid, creosoic acid (homosalicylic acid, hydroxy(methyl)benzoic acid), vanillic acid, syringic acid, Pyrocatechuic acid, resorcilic acid, protocatechuic acid, gentisic acid, orceric acid as dihydroxybenzoic acid derivatives, gallic acid as trihydroxybenzoic acid derivatives, mandelic acid, benzylic acid, atrolactinic acid, cinnamic acid and hydrocinnamic acid as phenylacetic acid derivatives Derivatives include melilotic acid, fluoretic acid, coumaric acid, umbelic acid, caffeic acid, ferulic acid, and sinapinic acid, and may be isomers thereof.

Examples of the compounds having a hydroxyl group and an amino group include alkanolamines having 2 to 12 carbon atoms, such as triethanolamine, diethanolamine, and monoethanolamine; and alkylalkanolamines having 2 to 12 carbon atoms, such as N-dimethyldiethanolamine.

Examples of the compounds having two or more carboxyl groups or salt groups thereof include aliphatic dicarboxylic acids having 2 to 6 carbon atoms, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and nosebacic acid, and salts thereof; aromatic dicarboxylic acids having 6 to 12 carbon atoms, such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid, and salts thereof; and divalent salts of monocarboxylic acids having 1 to 6 carbon atoms, such as formic acid and acetic acid.

Examples of the above-mentioned compounds having two or more amino groups or salt groups thereof include compounds having at least one guanidine group having 1 to 12 carbon atoms such as guanidine; compounds having at least one carbamide group such as urea; and ethylenediamine. (poly)alkylene polyamines having 1 to 12 carbon atoms; and salts thereof.

Examples of the compound having two or more sulfonic acid groups or salt groups thereof include alkanedisulfonic acids having 1 to 12 carbon atoms such as ethanedisulfonic acid, and salts thereof.
Examples of the compound having a hydroxyl group and a sulfonic acid group or a salt group thereof include hydroxyalkanesulfonic acids having 1 to 12 carbon atoms such as hydroxymethanesulfonic acid, and salts thereof.

Examples of compounds having two or more phosphate groups or salt groups thereof include polyphosphoric acids such as trimetaphosphoric acid, tripolyphosphoric acid, and pyrophosphoric acid, and salts thereof.

The functional group is preferably a hydroxyl group, a carboxyl group, and/or a salt group thereof.
That is, the compound (β) preferably has at least one hydroxyl group, at least one carboxyl group, or a salt group thereof.

The compound (β) is preferably a compound having two or more hydroxyl groups, and a compound having a hydroxyl group and a carboxyl group or a salt group thereof. More preferred are saccharides, monosaccharide oxides and their salts, oxycarboxylic acids other than the derivatives and their salts, still more preferred are saccharides, aldonic acids, aldaric acids and their salts, particularly preferred are glucose, These are trehalose, sucrose, gluconic acid (salt), and tartaric acid (salt).

The molecular weight of the compound (β) is 1000 or less, preferably 50 to 500, more preferably 100 to 400.

The precast cement admixture composition of the present invention can be used as a precast cement admixture by adding it to cement compositions such as cement paste, mortar, and concrete. It can also be used for ultra-high strength concrete. As the above cement composition, a commonly used one containing cement, water, fine aggregate, coarse aggregate, etc. is preferable. In addition, it may be a composition containing fine powder such as fly ash, blast furnace slag, silica fume, and limestone.
The term "ultra-high strength concrete" refers to what is generally referred to in the field of cement compositions, that is, concrete whose hardened product has the same or higher strength as conventional concrete even if the water-cement ratio is smaller than that of conventional concrete. For example, even if the water-cement ratio is 25% by mass or less, further 20% by mass or less, particularly 18% by mass or less, particularly 14% by mass or less, and particularly about 12% by mass, the concrete has workability that does not interfere with normal use, and the hardened product exhibits a compressive strength of 60 N/ ^mm2 or more, further 80 N/ ^{mm2 or} more, further 100 N/mm2 or more, particularly 120 N/ ^mm2 or more, particularly 160 N/ ^mm2 or more, and particularly 200 N/ ^mm2 or more.

The total content of the copolymer (α) and the compound (β) in the precast cement admixture composition of the present invention is not particularly limited, but is preferably 2% by mass or more and 50% by mass or less, more preferably 3% by mass or more and 40% by mass or less, even more preferably 4% by mass or more and 35% by mass or less, and particularly preferably 5% by mass or more and 30% by mass or less, based on 100% by mass of the solid content (i.e., non-volatile content) during the addition of cement.
In this specification, the term "cement admixture" refers to an admixture added to cement compositions such as cement paste, mortar, and concrete, and may be an agent consisting of the above-mentioned copolymer alone, or may be an agent containing not only the above-mentioned copolymer (α) and compound (β), but also other components, additives, and the like as necessary.

The precast cement admixture composition may further contain other commonly used cement dispersants and water-reducing agents, and multiple agents may be used in combination. There are no particular limitations on the other cement dispersants (water-reducing agents), but the following are suitable examples:

Lignosulfonate; polyol derivative; naphthalenesulfonic acid formalin condensate; melamine sulfonic acid formalin condensate; polystyrene sulfonate; Aminosulfonic acid type: as described in JP-A-7-267705, as component (a), a copolymer of a polyalkylene glycol mono(meth)acrylic acid ester compound and a (meth)acrylic acid compound and/or A salt thereof; as a component (b), a copolymer of a polyalkylene glycol mono(meth)allyl ether compound and maleic anhydride and/or a hydrolyzate thereof; and/or a salt thereof; and a component (c). A cement dispersant containing a polyalkylene glycol mono(meth)allyl ether compound and a copolymer of a maleic ester of a polyalkylene glycol compound and/or a salt thereof; described in Japanese Patent No. 2508113 Component A is a copolymer of polyalkylene glycol ester of (meth)acrylic acid and (meth)acrylic acid (salt), component B is a specific polyethylene glycol polypropylene glycol compound, and component C is a specific interface. Concrete admixture consisting of an activator; polyethylene (propylene) glycol ester of (meth)acrylic acid, polyethylene (propylene) glycol mono (meth) allyl ether, (meth) allyl sulfone as described in JP-A-62-216950; A copolymer consisting of acid (salt) and (meth)acrylic acid (salt).

A copolymer consisting of polyethylene (propylene) glycol ester of (meth)acrylic acid, (meth)allylsulfonic acid (salt), and (meth)acrylic acid (salt) as described in JP-A-1-226757; As described in Japanese Patent Publication No. 5-36377, polyethylene (propylene) glycol ester of (meth)acrylic acid, (meth)allylsulfonic acid (salt) or p-(meth)allyloxybenzenesulfonic acid (salt), and Copolymer consisting of (meth)acrylic acid (salt); copolymer of polyethylene glycol mono(meth)allyl ether and maleic acid (salt) as described in JP-A-4-149056; JP-A-5-170501 As described in the publication, polyethylene glycol ester of (meth)acrylic acid, (meth)allylsulfonic acid (salt), (meth)acrylic acid (salt), alkanediol mono(meth)acrylate, polyalkylene glycol mono(meth) A copolymer consisting of acrylate and an α,β-unsaturated monomer having an amide group in the molecule; polyethylene glycol mono(meth)allyl ether, polyethylene glycol mono( Copolymer consisting of meth)acrylate, (meth)acrylic acid alkyl ester, (meth)acrylic acid (salt), and (meth)allylsulfonic acid (salt) or p-(meth)allyloxybenzenesulfonic acid (salt) Coalescence: A copolymer of alkoxy polyalkylene glycol monoallyl ether and maleic anhydride as described in JP-A-5-43288, or a hydrolyzate thereof, or a salt thereof; as described in JP-A-58-38380 As described above, a copolymer consisting of polyethylene glycol monoallyl ether, maleic acid, and a monomer copolymerizable with these monomers, or a salt thereof, or an ester thereof.

As described in Japanese Patent Publication No. 59-18338, polyalkylene glycol mono(meth)acrylic acid ester monomers, (meth)acrylic acid monomers, and monomers copolymerizable with these monomers A copolymer consisting of a (meth)acrylic acid ester having a sulfonic acid group as described in JP-A-62-119147 and, if necessary, a monomer copolymerizable therewith; or its salt; as described in JP-A-6-271347, an esterification reaction product of a copolymer of alkoxypolyalkylene glycol monoallyl ether and maleic anhydride with a polyoxyalkylene derivative having an alkenyl group at the terminal; Esterification reaction product of a copolymer of alkoxy polyalkylene glycol monoallyl ether and maleic anhydride with a polyoxyalkylene derivative having a hydroxyl group at the terminal as described in JP-A No. 6-298555; JP-A No. 62-68806 As described in the publication, alkenyl ether monomers obtained by adding ethylene oxide, etc. to specific unsaturated alcohols such as 3-methyl-3-buten-1-ol, unsaturated carboxylic acid monomers, and these monomers. A polycarboxylic acid (salt) such as a copolymer consisting of a monomer copolymerizable with a monomer, or a salt thereof. These cement dispersants may be used alone or in combination of two or more.

Further, the precast cement admixture composition of the present invention may contain other additives, etc., if necessary. Other additives include water-soluble polymer substances, polymer emulsions, retardants, early strength agents/accelerators, antifoaming agents, AE agents, other surfactants, waterproofing agents, rust preventives, expansion materials, Cement wetting agent, thickener, separation reducing agent, flocculant, drying shrinkage reducing agent, strength enhancer, self-leveling agent, coloring agent, anti-mold agent, blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, Examples include silica fume, silica powder, and gypsum, and one or more of these can be used.

When using the above cement dispersants together, it cannot be determined unambiguously due to differences in the type, composition, test conditions, etc. of the cement dispersants used, but the combined mass of the above cement dispersants with the other additives, etc. above. The ratio is preferably 5-95:95-5. More preferably, the ratio is 10-90:90-10.

The above cement admixture composition for precasting can be used for various hydraulic materials, that is, cement compositions such as cement and gypsum, and other hydraulic materials. As a specific example of a hydraulic composition containing such a hydraulic material, water, and the above-mentioned cement admixture composition, further containing fine aggregate (sand, etc.) or coarse aggregate (crushed stone, etc.) as necessary. Examples include cement paste, mortar, concrete, plaster, etc. Among these hydraulic compositions, a cement composition using cement as a hydraulic material is most preferable, and a precast cement composition containing the above-mentioned precast cement admixture composition and cement is also one of the present invention. It is one.

<Cement composition for precasting>
In the cement composition for precasting of the present invention, cements include Portland cement (normal, early strength, ultra early strength, moderate heat, sulfate resistant, and low alkali types of each); various mixed cements (blast furnace cement, silica cement, Fly ash cement); White Portland cement; Alumina cement; Super fast hardening cement (1 clinker fast hardening cement, 2 clinker fast hardening cement, magnesium phosphate cement); Cement for grout; Oil well cement; Low heat generation cement (low heat generation blast furnace cement) , fly ash mixed low heat generation blast furnace cement, high Blite content cement); ultra-high strength cement; cement solidifying agent; ecocement (cement manufactured using one or more of the following raw materials: municipal waste incineration ash, sewage sludge incineration ash) ), as well as those to which fine powders such as blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, silica fume, silica powder, limestone powder, and gypsum are added. The precast cement composition of the present invention may contain only one type of cement, or may contain two or more types of cement.
In addition to gravel, crushed stone, granulated slag, recycled aggregate, etc., the above-mentioned aggregates include silica, clay, zircon, high alumina, silicon carbide, graphite, chromium, chromatic, magnesia, etc. Examples include refractory aggregates, etc.

In the above cement composition for precasting, the unit water amount, cement usage amount, and water/cement ratio per 1 m ³ are not particularly limited, and for example, the unit water amount is 100 to 185 kg/m ³ and the cement usage amount is 250 to 800 kg/m. ^3. The water/cement ratio (weight ratio) is preferably 0.12 to 0.74. More preferably, the unit water amount is 120 to 175 kg/m ³ , the cement amount used is 270 to 800 kg/m ³ , and the water/cement ratio (weight ratio) is 0.15 to 0.65. As described above, the precast cement composition of the present invention can be used in a wide range of situations, from poor to rich mixes, and can be used for both high-strength concrete with a large unit cement content and poor mix concrete with a unit cement content of 300 kg/m ³ or less. is also valid. Furthermore, the precast cement composition of the present invention is suitable for use in a relatively high water reduction rate region, that is, a water/cement ratio (weight ratio) of 0.15 to 0.5 (preferably 0.15 to 0.4). It can be used successfully even in areas with low water/cement ratios.

In the precast cement composition, the blending ratio of the cement admixture composition of the present invention is preferably set so that the total amount of the copolymer (α) and compound (β) is 0.0005 to 10 mass% relative to the total amount of cement mass of 100 mass% in terms of solid content. If it is less than 0.0005 mass%, the performance may not be sufficient, and conversely, if it exceeds 10 mass%, the effect may substantially plateau and may be disadvantageous from the economical point of view. It is more preferably 0.001 to 5 mass%, and even more preferably 0.005 to 1 mass%. In this specification, the solid content can be measured as follows.
In the precast cement composition, the amount of compound (β) is preferably set to 0.0005 to 1 mass% in terms of solid content relative to 100 mass% of the total cement mass. This allows the early strength development to be further improved. It is more preferably 0.001 to 0.5 mass%, and even more preferably 0.005 to 0.1 mass%.
In this specification, the solid content can be measured as follows.
<Solid content measurement method>
1. Accurately weigh the aluminum dish.
2. Accurately weigh the solids content measurement sample into the aluminum dish used in step 1.
3. The solid content measurement sample accurately weighed out in step 2 is placed in a dryer adjusted to 130° C. under a nitrogen atmosphere for 1 hour.
4. After 1 hour, remove from the dryer and allow to cool in a desiccator at room temperature for 15 minutes.
5. After 15 minutes, remove from the desiccator and accurately weigh the aluminum dish plus the sample.
6. The mass of the aluminum dish obtained in step 1 is subtracted from the mass obtained in step 5, and the result is divided by the mass of the solids measurement sample obtained in step 2 to measure the solids content.

By using the cement admixture composition for precasting of the present invention, the resulting cement composition has excellent early strength development properties, so it can be effectively applied to precast cement (precast concrete).
The present invention also provides a method for producing a cured cement product, which includes the steps of mixing the cement admixture composition for precasting with cement, and curing the composition obtained in the mixing step at 15 to 90°C. . The curing temperature is preferably 40 to 85°C, more preferably 50 to 85°C, even more preferably 55 to 85°C, particularly preferably 60 to 80°C.

In the above manufacturing method, the curing step is preferably performed at a humidity of 40% to 100%. More preferably the humidity is 50 to 100%, even more preferably 60 to 100%.

The curing step may be performed in one stage or in two or more stages, but is preferably performed in two stages. It is preferable to carry out the first stage under conditions of a temperature of 15 to 50°C and a humidity of 40 to 60%, and a second stage under conditions of a temperature of 60 to 90°C and a humidity of 60 to 100%.

The manufacturing method preferably includes a step of pouring the composition obtained in the mixing step into a mold, and the curing step is preferably performed after the step of pouring into the mold.

In the manufacturing method, the curing step is preferably performed by steam curing.

In the above manufacturing method, the curing step is preferably carried out for 1 to 10 hours. More preferably 1.5 to 8 hours, still more preferably 2 to 6 hours.

The present invention also relates to a method for hardening cement, in which a composition containing the above-mentioned precast cement admixture composition and cement is hardened at 40 to 90°C. The preferred hardening temperature is the same as that of the above-mentioned method for producing a hardened cement product.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples. In addition, unless otherwise specified, "parts" shall mean "parts by mass" and "%" shall mean "% by mass."

<Production Example 1> Production of water reducing agent (polycarboxylic acid copolymer α) 72.26 parts of ion-exchanged water and 3-methyl-3 were placed in a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, and a reflux condenser. - 127.74 parts of an unsaturated alcohol prepared by adding 50 moles of ethylene oxide to buten-1-ol was charged, the temperature was raised to 65°C, 0.71 part of a 30% aqueous hydrogen peroxide solution was added thereto, and acrylic acid was added. 46.58 parts of a 40% aqueous solution was added dropwise over 3 hours, 0.67 parts of 3-mercaptopropionic acid was added over 3 hours, and 12.97 parts of a 2.1% L-ascorbic acid solution was added dropwise over 3.5 hours. Thereafter, the temperature was maintained at 65°C for 60 minutes to complete the polymerization reaction, and the temperature was lowered to below 50°C and neutralized with 76.07 parts of a 12.2% sodium hydroxide aqueous solution from pH 4 to pH 7. A polycarboxylic acid copolymer of the present invention consisting of an aqueous polymer solution having a weight average molecular weight of 29,000 was obtained. Incidentally, the total amount of monomers used with respect to the total amount of raw materials used during polymerization was 56.2% by weight.

<Mortar test>
Preparation of mortar samples:
The mortar test was conducted in an environment with a temperature of 20° C.±1° C. and a relative humidity of 60%±15%. The mortar composition was C/S/W=535/1350/214 (g).
however,
C: Cement (ordinary Portland cement, manufactured by Taiheiyo Cement Co.)
S: Fine aggregate (standard sand for cement strength testing, manufactured by Cement Association)
W: An ion-exchanged aqueous solution of a sample and an antifoaming agent.W contained additives for hydraulic materials and an antifoaming agent obtained in the following Examples and Comparative Examples, and was sufficiently and uniformly dissolved in ion-exchanged water.
Using a mortar mixer (mixer manufactured by Hobart, model number: N-50), S and W were charged into a kneading container and kneaded at 1 speed for 40 seconds. Furthermore, C was added over 20 seconds while kneading at 1st speed. 60 seconds after starting kneading, the speed was changed to 2nd speed, and kneading was continued for an additional 30 seconds. Thereafter, the mixer was stopped, the mortar was scraped off for 30 seconds, and the mixture was allowed to stand for 60 seconds. Thereafter, kneading was further performed at 2 speed for 60 seconds to prepare mortar. The amount of air was adjusted to less than 3.0% by adding an oxyalkylene antifoaming agent.

<Measurement of compressive strength>
After kneading, a sample for compressive strength test was prepared, and the compressive strength after steam curing was measured under the following conditions.
Specimen creation: 50mm x 100mm
Curing of specimen: After curing in constant temperature and humidity air for 2 hours at a temperature of 20° C. and humidity of 50%, curing was performed for another 2 hours at a temperature of 60° C. and a humidity of 98% using a constant temperature and humidity oven.
Specimen polishing: Specimen surface polishing (using specimen polishing finishing machine)
Compressive strength measurement: Automatic compressive strength measuring device (Maekawa Seisakusho)

Example 1
Sodium gluconate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (1).

[Example 2]
Sodium gluconate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was blended as the compound (β) under the conditions shown in Table 1 to prepare an admixture for cement (2).

[Example 3]
Sucrose (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was blended as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (3).

[Example 4]
Urea (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was blended as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (4).

[Example 5]
Sodium gluconate (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was blended as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (5).

Example 6
Sodium gluconate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (6).

Example 7
Glucose (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (7).

[Example 8]
Sodium glucoheptonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was blended as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (8).

[Example 9]
Fructose (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was blended as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (9).

[Example 10]
A cement admixture (10) was prepared by blending L-tartaric acid (manufactured by Fuso Chemical Industries, Ltd.) as the compound (β) under the conditions shown in Table 1.

Example 11
Trehalose (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as compound (β) under the conditions shown in Table 1 to prepare a cement admixture (11).

[Comparative example 1]
A cement admixture (12) was prepared by adding only the polymer (α) without using the compound (β).

Comparative Example 2
Sodium gluconate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (13).

[Comparative example 3]
Sucrose (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was blended as the compound (β) under the conditions shown in Table 1 to prepare an admixture for cement (14).

[Comparative example 4]
Sodium hexametaphosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was blended as the compound (β) under the conditions shown in Table 1 to prepare a cement admixture (15).

Compressive strength was measured using the cement admixtures obtained in Examples 1 to 11 and Comparative Examples 1 to 4 by the method described above. The results are shown in Table 1.
The strength ratio was expressed as a ratio to Comparative Example 1, which is the strength when no additives were added.

Claims (14)

A method for producing a cured cement product, the method comprising:
The manufacturing method includes a step of mixing a cement admixture composition for precasting with cement, and a step of curing the composition obtained in the mixing step under conditions of 40 to 90 ° C. and 40 to 100% humidity. ,
The precast cement admixture composition comprises a structural unit (a1) derived from an unsaturated carboxylic acid monomer (A1) and a structural unit (a2) derived from a (poly)alkylene glycol monomer (A2). A copolymer (α) having
It has a hydroxyl group, and two or more functional groups selected from the group consisting of a carboxyl group, an amino group, a sulfonic acid group, a phosphoric acid group, a phosphorous acid group, and a salt group thereof, and has a molecular weight of 1000 or less. Compound (β)
A method for producing a cured cement product , characterized in that the content of the compound (β) is 0.1 to 7% by mass based on 100% by mass of the copolymer (α). The method for producing a cured cement product according to claim 1, wherein the compound (β) has a hydroxyl group. 3. The method for producing a cured cement product according to claim 1, wherein the compound (β) has a carboxyl group and/or a salt group thereof. The method for producing a cured cement product according to any one of claims 1 to 3, wherein the compound (β) has a hydroxyl group, a carboxyl group, and/or a salt group thereof. The method for producing a cured cement product according to any one of claims 1 to 4, wherein the compound (β) has two or more hydroxyl groups. The method for producing a hardened cement product according to any one of claims 1 to 5, characterized in that the compound (β) contains at least one selected from the group consisting of saccharides; oxides of monosaccharides and their salts; and oxycarboxylic acids other than the oxides and their salts. The method for producing a cured cement product according to any one of claims 1 to 6, wherein the compound (β) contains an aldonic acid (salt). The method for producing a cured cement product according to claim 1, wherein the compound (β) includes a compound having two or more amino groups or salt groups thereof. The compound (β) is at least one selected from sucrose, fructose, trehalose, glucose, gluconic acid (salt), tartaric acid (salt), glucoheptonic acid (salt), and urea. 1. The method for producing a cured cement product according to 1. The (poly)alkylene glycol monomer (A2) has the following formula (1);

(In the formula, R ¹ , R ² and R ³ are the same or different and represent a hydrogen atom or a methyl group. R ⁴ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms. (R ⁵ O) are the same or different and represent an oxyalkylene group. n represents the average number of added moles of the oxyalkylene group and is a number from 1 to 300. x represents a number from 0 to 4. The method for producing a cured cement product according to any one of claims 1 to 9 , wherein y represents 0 or 1. The method for producing a hardened cement product according to any one of claims 1 to 10 , characterized in that, in the (poly)alkylene glycol monomer (A2), y in the formula (1) is 0. The method for producing a hardened cement product according to any one of claims 1 to 11, characterized in that the hardening step is carried out by steam curing. 13. The method for producing a cured cement product according to claim 1, wherein the curing step is performed for 1 to 10 hours . A method of curing cement, the method comprising:
The curing method includes a step of curing a composition containing a precast cement admixture composition and cement at a temperature of 40 to 90°C and a humidity of 40 to 100% ,
The precast cement admixture composition comprises a structural unit (a1) derived from an unsaturated carboxylic acid monomer (A1) and a structural unit (a2) derived from a (poly)alkylene glycol monomer (A2). A copolymer (α) having
It has a hydroxyl group, and two or more functional groups selected from the group consisting of a carboxyl group, an amino group, a sulfonic acid group, a phosphoric acid group, a phosphorous acid group, and a salt group thereof, and has a molecular weight of 1000 or less. Compound (β)
A method for curing cement, characterized in that the content of the compound (β) is 0.1 to 7% by mass based on 100% by mass of the copolymer (α) .