JPH10330143A - Additive for cement and cement composition and cement hardened material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an additive for cement used for suppressing deterioration of neutralization, etc., in cement hardened material. SOLUTION: This additive for cement consists essentially of a polymer containing a structural unit represented by the formula [R<3> represents hydrogen atom or an organic residue; R<4> represents hydrogen atom, methyl group or CHR<6> OH group; R<5> is represents hydrogen atom, methyl group, COOR<7> group or phenyl group and R<6> represents hydrogen atom or an organic residue; R<7> is hydrogen atom, a monovalent metal ion or a divalent amine group and (m) is an integer of 1 or 2]. Since the additive for cement containing the polymer is excellent in acid resistance, the additive sufficiently can suppress deterioration, etc., of cement hardened material. The structure of the polymer is confirmed by measurement of infrared absorption spectrum (IR) and elementary analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an additive for cement, a cement composition, and a hardened cement. More specifically, an additive for cement for suppressing deterioration such as neutralization of a cement hardened product due to acid rain caused by exhaust gas and the like, and a cement composition containing the additive for cement, and the cement The present invention relates to a cured cement obtained by curing a composition. In the present invention, cement is an inorganic powder that is hardened by reacting with water by kneading with water, Portland cement, various mixed cements, alumina cement, slaked lime,
It is a general term for gypsum and the like.

[0002]

2. Description of the Related Art In recent years, deterioration of concrete structures such as road bridges due to severe environmental changes has been reported, and deterioration in the strength and durability of concrete structures has become a social problem. One of the causes of such deterioration of the concrete structure is, for example, neutralization of concrete due to acid rain or the like caused by exhaust gas or the like. For this reason, in order to suppress the neutralization of concrete, a method of covering the concrete surface with a protective material, a method of dispersing specific amines in cement constituting the concrete (Japanese Patent Laid-Open No. 22157/1990), a polymer A method of adding an acrylic styrene copolymer as a dispersion (Cement Technical Annual Report, No. 42, 499 (1988)) has been proposed.

[0003]

However, in the above method, it is necessary to coat a protective material on the concrete structure after building the concrete structure, and the process up to the completion of the concrete structure is complicated. Become. Furthermore, in the above method, when a crack occurs in the protective material that coats the surface of the concrete structure, the deterioration proceeds from the cracked portion, so that it cannot be said that the neutralization of the concrete can be sufficiently suppressed.

[0004] Further, the above-mentioned method contributes to the suppression of deterioration of concrete at an early stage, but has a problem that its deterioration suppressing ability decreases with time. In addition, since the amines are dispersed in the cement, the odor of the amines may cause a problem.

Further, the above method is a method of suppressing the water permeability of concrete by the hydrophobicity of the polymer, and cannot be said to be a method which exerts a sufficient effect for suppressing the neutralization of concrete.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an additive for cement for suppressing deterioration such as neutralization of a cement hardened product such as concrete. It is in. Another object of the present invention is to provide a cement composition which is excellent in acid resistance and can obtain a hardened cement material in which deterioration such as neutralization is suppressed. Still another object of the present invention is to provide a hardened cement material which is excellent in acid resistance and in which deterioration such as neutralization is suppressed.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that the use of a polymer containing a specific structural unit as an additive for cement makes it possible to deteriorate the hardened cement. It has been found that the present invention can be suppressed, and the present invention has been completed.

That is, the additive for cement according to the first aspect of the present invention has the general formula (1)

[0009]

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(Wherein, R ¹ represents a hydrogen atom or an organic residue; R ² represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group;
Or represents an integer of 2).

In order to solve the above-mentioned problems, the additive for cement according to the invention of claim 2 has the general formula (2)

[0012]

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(Wherein, R ³ represents a hydrogen atom or an organic residue, and R ⁴ represents a hydrogen atom, a methyl group or —CHR ⁶ OH
R ⁵ represents a hydrogen atom, a methyl group, —COOR
⁷ represents a phenyl group; R ⁶ represents a hydrogen atom or an organic residue; R ⁷ represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group; Or represents an integer of 2).

According to a third aspect of the present invention, there is provided an additive for cement, which has the general formula (1)

[0015]

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(Wherein, R ¹ represents a hydrogen atom or an organic residue, R ² represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group;
Or an integer of 2) and a general formula (2)

[0017]

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(Wherein R ³ represents a hydrogen atom or an organic residue, and R ⁴ represents a hydrogen atom, a methyl group or —CHR ⁶ OH
R ⁵ represents a hydrogen atom, a methyl group, —COOR
⁷ represents a phenyl group; R ⁶ represents a hydrogen atom or an organic residue; R ⁷ represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group; Or an integer of 2) in the same molecule.

According to the constitutions of claims 1 to 3, it is possible to provide a cement additive which has excellent acid resistance and can sufficiently suppress deterioration such as neutralization of a hardened cement.

In order to solve the above-mentioned problems, the cement composition of the invention according to claim 4 includes the cement additive according to any one of claims 1 to 3 and cement. It is characterized by.

[0021] In order to solve the above-mentioned problems, a cement hardened material according to the present invention is obtained by hardening the cement composition according to the present invention.

According to the above construction, the additive for cement according to any one of claims 1 to 3 is excellent in acid resistance and can sufficiently suppress deterioration such as neutralization of the cured cement.
The cement composition containing the additive for cement also has excellent ability to suppress the deterioration of the hardened cement. Therefore, by using the cement composition, it is possible to provide a hardened cement material which is excellent in acid resistance and in which deterioration such as neutralization is suppressed.

Hereinafter, the present invention will be described in detail. The additive for cement according to the present invention contains a structural unit represented by the general formula (1) in a main chain thereof, in order to suppress deterioration of a hardened cement.
The substituent represented by R ¹ is independently composed of a hydrogen atom or an organic residue for each —CHR ¹ — group, and the substituent represented by R ² is a hydrogen atom, a monovalent metal ion, a divalent metal ion, A polymer comprising an ammonium group and an organic amine group, wherein the repeating unit represented by n is an integer of 0, 1 or 2;
Alternatively, the structural unit represented by the general formula (2) is contained in the main chain, and the substituent represented by R ³ is independently composed of a hydrogen atom or an organic residue for each —CHR ³ — group; substituent is a hydrogen atom represented by ^4, a methyl group or a -CHR ⁶ O
Consists of H, substituted group represented by R ⁵ is a hydrogen atom, a methyl group, -COOR ⁷ group, consists of a phenyl group, R ⁶
Is a hydrogen atom or an organic residue, and the substituent represented by R ⁷ is a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group. Wherein the repeating unit represented by the formula (1) is a polymer having an integer of 0, 1 or 2, or the structural unit represented by the general formula (1) or (2) is represented by R ¹ in the same molecule. The substituent is independently a hydrogen atom or an organic residue for each —CHR ¹ — group, and the substituent represented by R ² is a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, an organic amine. R ³
Is independently a hydrogen atom or an organic residue for each —CHR ³ — group, the substituent represented by R ⁴ is a hydrogen atom, a methyl group or a —CHR ⁶ OH group, A substituent represented by R ⁵ is a hydrogen atom, a methyl group, -C
OOR ⁷ group, a phenyl group, a substituent represented by R ⁶ is a hydrogen atom or an organic residue, and a substituent represented by R ⁷ is a hydrogen atom, a monovalent metal ion, a divalent metal ion, ammonium And a polymer composed of an organic amine group, wherein the repeating unit represented by n and the repeating unit represented by m are each independently an integer of 0, 1 or 2.

Among the substituents represented by R ¹ , R ³ and R ⁶ , examples of the organic residue include an alkyl group having 1 to 18 carbon atoms, an aryl group, and a heterocyclic group. More specifically, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, n-hexyl group, cyclohexyl group, n-octyl group, 2-ethylhexyl group, C1-C12 straight or branched chain alkyl group such as lauryl group; C6-C12 unsubstituted or substituted aryl group such as phenyl group, toluyl group, xylyl group, naphthalene group and benzyl group. A hydroxyalkyl group having 1 to 6 carbon atoms such as a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 4-hydroxybutyl group, and a 6-hydroxyhexyl group. .

Further, among the substituents represented by R ² and R ⁷ , specific examples of the monovalent metal ion include a lithium ion, a sodium ion, and a potassium ion. Specific examples of the divalent metal ion include a magnesium ion, a calcium ion, and a barium ion. Further, the organic amine group refers to a substituted amino group. Specifically, one hydrogen atom bonded to a nitrogen atom is removed from organic amines such as ethylenediamine, N-alkyl-substituted polyamine, polyethylene polyamine, and alkanolamine. Indicates a separated group.

Among polymers (polymers, polymers) containing the structural unit represented by the general formula (1),
A polymer in which the repeating unit represented by m is 1 is preferable, and a polymer in which the substituent represented by R ¹ is a hydrogen atom is more preferable, and among them, the substituent represented by R ² is hydrogen. A polymer which is an atom is particularly preferable because it is more excellent in acid resistance.

Further, among the polymers (polymers, polymers) containing the structural unit represented by the general formula (2), the substituent represented by R ³ is a hydrogen atom and represented by R ⁴ . substituent is -CH ₂ OH group, the polymer substituent represented by R ⁵ is -COOR ⁷ group is preferably because it is excellent in acid resistance, among them, the substituents represented by R ⁷ A polymer which is a hydrogen atom and has a repeating unit represented by m of 1 is particularly preferred.

Among the polymers containing the structural unit represented by the general formula (2), particularly, the polymer wherein the substituent represented by R ⁷ is a hydrogen atom and the repeating unit represented by m is 1 Has excellent pH responsiveness and is particularly excellent in acid resistance. Therefore, the concrete deterioration inhibitor containing the polymer is particularly excellent in the ability to suppress deterioration such as carbonation of concrete.

The method for producing the polymer containing the structural unit represented by the general formula (1) is not particularly limited, and examples thereof include α- (hydroxymethyl) acrylates and α- (1- Hydroxyethyl) acrylates,
α- (1-hydroxypropyl) acrylates, α-
(1-hydroxybutyl) acrylates, α- (1-
Hydroxyl-containing monomers such as hydroxyhexyl) acrylates and α- (1-hydroxybenzyl) acrylates are polymerized alone or (co) polymerized with a monomer copolymerizable with the hydroxyl-containing monomer. Then, the (co) polymer obtained is easily produced by hydrolysis with an alkaline substance.

In the present invention, the polymerization method of the monomer component containing the above-mentioned hydroxyl group-containing monomer is not particularly limited. For example, a polymerization method using a polymerization initiator such as a radical polymerization initiator; Radiation such as electron beams,
Conventionally known various methods such as a polymerization method of irradiating ultraviolet rays and a polymerization method by heating can be employed.

The above-mentioned hydroxyl group-containing monomer can be prepared by a conventionally known method, for example, by reacting a corresponding vinyl compound and an aldehyde compound in the presence of a tertiary amine compound and water as a catalyst (Japanese Unexamined Patent Application Publication No. 7-285906) or the like.

Specific examples of the monomer copolymerizable with the above-mentioned hydroxyl group-containing monomer include maleic anhydride, maleic acid and its salts, maleic ester, fumaric ester, itaconic acid and its salts, and itaconic Examples thereof include acid esters, styrene, vinyl acetate, acrylonitrile, (meth) acrylamide, allyl alcohol, ethylene, propylene, and vinyl chloride, but are not particularly limited.

Examples of the polymerization initiator include peroxides such as benzoyl peroxide and tert-butyl peroxide;
Azo compounds such as azobisisobutyronitrile; and persulfates. Further, the amount of the polymerization initiator used, the reaction conditions for the polymerization reaction, and the like are not particularly limited.

As the above-mentioned alkaline substance, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonia or an aqueous solution thereof is used.

As another method for producing a polymer containing the structural unit represented by the general formula (1), for example, α-
A method of hydrolyzing the obtained (co) polymer after (co) polymerizing the chloroacrylic acid alone or a monomer copolymerizable with the α-chloroacrylic acid, and the like. However, there is no particular limitation.

The weight average molecular weight (Mw) of the polymer containing the structural unit represented by the general formula (1), measured by GPC (gel permeation chromatography) using sodium polystyrene sulfonate as a standard sample, is:
It is preferably in the range of 1,000 to 1,000,000, and more preferably in the range of 5,000 to 500,000. When the weight average molecular weight is within the above range, handling is easy, and it can be easily mixed with cement. On the other hand, if the weight-average molecular weight exceeds 1,000,000, the viscosity becomes too high and the workability may be reduced.

The polymer containing the structural unit represented by the general formula (1) may have a structure in which the structural units represented by the general formula (1) are bonded in blocks or randomly. . In other words, the polymer / polymer depends on, for example, the type of the hydroxyl group-containing monomer and the monomer component containing the hydroxyl group-containing monomer.

[0038]

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(Wherein, R ¹ represents a hydrogen atom or an organic residue, R ² represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group; R ⁸ represents a hydrogen atom; It represents a methyl group or a -CHR ¹⁰ OH group,, R ⁹
It represents a hydrogen atom, a methyl group, -COOR ¹¹ group, a phenyl group, R ¹⁰ represents a hydrogen atom or an organic residue, R ¹¹ is a hydrogen atom, a monovalent metal ion, a bivalent metal ion, an ammonium group, an organic amine Represents a group, n represents an integer of 0, 1 or 2, p represents 0 or an integer of 1 or more, and q represents an integer of 1 or more).

Among the polymers containing the structural unit represented by the general formula (1), a polymer in which two or more structural units represented by the general formula (1) are block-bonded, In the formula (3), the repeating unit represented by q is 2
The above-mentioned polymers are preferable because a lactone ring is easily formed by adjusting the pH, and a polymer having excellent pH responsiveness can be obtained. Further, when the polymer including the structural unit represented by the general formula (1) includes the structural unit represented by the general formula (3), the repeating unit represented by p is 0.
Alternatively, it is preferably an integer of 1 to 20, and the repeating unit represented by q is preferably an integer of 1 to 20, and more preferably an integer of 2 to 20. In the general formula (3), when the repeating unit represented by p and q is within the above range, an additive for cement that is particularly excellent in handleability and the like can be obtained.

In this embodiment, the polymer containing the structural unit represented by the general formula (3) is exemplified as the polymer containing the structural unit represented by the general formula (1). The polymer containing the structural unit represented by the general formula (1) is not limited thereto, and structural units other than the structural unit represented by the general formula (1) are not particularly limited. Not something. Similarly, in the polymer represented by the general formula (2), structural units other than the structural unit represented by the general formula (2) are not particularly limited.

The method for producing the polymer containing the structural unit represented by the general formula (2) is not particularly limited, but includes, for example, the polymer containing the structural unit represented by the general formula (1). It can be easily obtained by treating the polymer with an acid. Specifically, for example, a polymer having a structural unit represented by the general formula (2) is obtained by adding an acid to the above-mentioned polymer, mixing the mixture, and heating if necessary, whereby the polymer is lactone-cyclized. That is, a polymer or a lactone ring-containing polymer as a polymer can be obtained.

Specific examples of the acid used in the acid treatment (lactone cyclization treatment) include mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and polyphosphoric acid; methanesulfonic acid, paratoluenesulfonic acid, and trifluoroacetic acid. And the like; heteropoly acids such as phosphotungstic acid and phosphomolybdic acid; and the like. The above acids may be used alone,
Two or more types may be used as appropriate. Among the above acids,
Hydrochloric acid and sulfuric acid are particularly preferred.

The above-mentioned acid may be used as a solution dissolved in water or an inert organic solvent, or may be used as a suspension suspended in water or an inert organic solvent. It may be used as a solid.

When the acid is added to the polymer containing the structural unit represented by the general formula (1), the polymer containing the structural unit represented by the general formula (1) is added to an aqueous solution (polycarboxylic acid). It is preferable to add an acid to the aqueous solution. The above treatment may be carried out uniformly or in a heterogeneous system containing an inert organic solvent insoluble in water, but it is more preferable to use a uniform aqueous system. Further, the acid may be added all at once or sequentially. The time required for mixing the polymer containing the structural unit represented by the general formula (1) with the acid is not particularly limited.

The treatment temperature at the time of lactone cyclization by adding an acid to the polymer containing the structural unit represented by the general formula (1) is such that the lactone cyclization reaction proceeds rapidly, and decarboxylation or Since there are few problems such as formation of a gelled product,
The temperature is preferably in the range of 150C to 150C, more preferably in the range of 200C to 80C.

The amount of the acid to be added to the polymer containing the structural unit represented by the general formula (1) is such that the polymer containing the structural unit represented by the general formula (1) shows acidity. Preferably, the pH of the treatment liquid is 5 or less,
It is desirable to add the acid so that it is more preferably 3 or less, particularly preferably 2 or less. By adding an acid so that the treatment liquid containing the polymer containing the structural unit represented by the general formula (1) exhibits acidity, the polymer containing the structural unit represented by the general formula (1) becomes By lactone cyclization, a lactone ring-containing polymer having a structural unit represented by the general formula (2) is obtained.

In this case, the polymer containing the structural unit represented by the general formula (1) is particularly preferably a polymer having the general formula (4)

[0049]

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(Wherein R ¹ and R ¹² each independently represent a hydrogen atom or an organic residue): a polymer obtained by hydrolyzing a homopolymer of a hydroxyl group-containing monomer represented by the formula: Then, the water-insoluble lactone ring-containing polymer can be separated and purified as a precipitate by treating it with an acid so that the pH of the treatment liquid containing the polymer becomes 3 or less. still,
Among the substituents represented by R ¹² above, examples of the organic residue include:
For example, a C1-C18 alkyl group, an aryl group, a heterocyclic group, etc. are mentioned.

Hereinafter, a method for producing a polymer containing the structural unit represented by the general formula (1) and / or the structural unit represented by the general formula (2), that is, the above-mentioned polymer, polymer or The method for producing the polymer will be described more specifically, but the method for producing each of the above polymers is not limited thereto.

First, for example, α- (hydroxymethyl) ethyl acrylate is used as a raw material, which is dissolved in ion-exchanged water, and then subjected to radical polymerization using potassium persulfate as an initiator. (Homopolymer) is obtained as a slurry. Next, an equimolar amount of an aqueous sodium hydroxide solution is added to the above-mentioned polymer, followed by hydrolysis to obtain a polymer containing the structural unit represented by the general formula (1) as an aqueous solution. Then, by adding a dilute sulfuric acid aqueous solution to the polymer at 30 ° C. so as to have a pH of 2.8, the polymer containing the structural unit represented by the general formula (2) is converted into a water-insoluble polymer. It can be obtained as a white solid lactone ring-containing polymer. The polymer obtained in this manner is filtered and dried,
It can be easily separated and purified as a white powder.

The above-mentioned polymer, polymer or polymer used as an additive for cement according to the present invention is mixed with cement as an agent for suppressing deterioration of the hardened cement, thereby neutralizing the resulting hardened cement. Degradation can be suppressed. The polymer, the polymer or the polymer may be used alone as an additive for cement.However, if necessary, the polymer, the polymer or an additive other than the polymer, for example, naphthalenesulfonic acid formaldehyde Condensate or salt thereof, alkylnaphthalenesulfonic acid formaldehyde condensate or salt thereof, ligninsulfonic acid or salt thereof, melaminesulfonic acid formaldehyde condensate or salt thereof, oxycarboxylic acid or salt thereof, polycarboxylic acid or salt thereof, polyalkyl Known dispersants such as carboxylic anhydrides or salts thereof, polyalkylene glycol-containing polycarboxylic acids or salts thereof, curing retarders, curing accelerators, air entrainers, A
E water reducer, high performance AE water reducer, cement wetting and dispersing agent, waterproofing agent, defoamer, foaming agent, strength enhancer, water retention agent, rust inhibitor,
It may contain a known cement admixture such as a coloring agent, a fungicide, a crack reducing agent, a swelling agent, and a polymer emulsion, other surfactants, a water-soluble polymer, and glass fiber.

The content of the above-mentioned polymer, polymer or polymer in the cement additive is preferably 3 in that acid resistance is excellent and deterioration of the hardened cement can be sufficiently suppressed.
It is preferably at least 0% by weight, more preferably at least 50% by weight, particularly preferably at least 80% by weight.

The timing of adding and mixing (mixing) the above-mentioned additive for cement to cement or a cement mixture is not particularly limited. For example, the above-mentioned additive for cement is dry-blended with cement in advance. Alternatively, it may be dispersed or dissolved in kneading water, and may be added at the time of kneading the cement composition. When the cement additive is added at the time of kneading the cement composition, the cement additive may be added simultaneously with water injection into the cement. It may be added until the end. Also,
The additives for cement may be added all at once or sequentially.

Further, when the cement additive is mixed with the cement, the cement additive may be added as an aqueous solution, a dispersion or a powder. In addition, when the cement additive includes the polymer, the polymer, or various additives described above in addition to the polymer as other additives, the polymer, the polymer, or the polymer and the other additives The agent may be used by mixing (kneading) it in advance, or one may be mixed with cement or a cement mixture, and then the other may be mixed.

The cement composition of the present invention comprises at least
It comprises the above cement additive and cement. In the present invention, cement is an inorganic powder that hardens by reacting with water when kneaded with water, and is a general term for Portland cement, various mixed cements, alumina cement, slaked lime, gypsum, and the like.

More specifically, the above-mentioned cements include ordinary Portland cement, early-strength Portland cement, moderately heated Portland cement, alumina cement, fly ash cement, blast furnace cement, silica cement and the like. Ordinary Portland cement is preferably used.

The content of the cement additive in the above cement composition depends on the kind of the cement additive to be used, the kind of the cement and the like. % By weight is preferred,
More preferably in the range of 0.5% by weight to 10% by weight,
Particularly preferred is a range of 0.5% to 5% by weight.

The above-mentioned cement composition is, for example,
It may contain fine aggregates and coarse aggregates generally used in the production of hardened cement products such as concrete, water, and other usual additives used in conventional cement compositions.

Then, the cement composition of the present invention can be obtained by reacting the above-mentioned cement composition with water to cure the cement composition. The hardened cement of the present invention is not particularly limited, and examples thereof include concrete, mortar, slate, block, gypsum board and the like.

As described above, the cement additive of the present invention contains a polymer containing the structural unit represented by the general formula (1) or a polymer containing the structural unit represented by the general formula (2). It comprises a polymer or a polymer containing the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2) in the same molecule. Further, the cement composition of the present invention comprises the above-mentioned additive for cement and cement. And the hardened cement of the present invention is obtained by hardening the above cement composition.

The additive for cement of the present invention is excellent in acid resistance and can sufficiently suppress deterioration such as neutralization of cured cement. Further, as described above, since the cement additive is excellent in the ability to inhibit the deterioration of the hardened cement, the cement composition of the present invention containing the additive for cement also has the ability to inhibit the deterioration of the hardened cement. Are better. Therefore, by using the cement composition, it is possible to provide a hardened cement material which is excellent in acid resistance and in which deterioration such as neutralization is suppressed.

It is not clear why the cement additive of the present invention is excellent in acid resistance and has a more excellent ability to suppress the deterioration of a hardened cement product than in the past. One of the reasons is as follows. The polymer containing the structural unit represented by 1) and / or the structural unit represented by the general formula (2) has pH responsiveness, for example.
As described above, the polymer containing the structural unit represented by the general formula (1) becomes a polymer containing the structural unit represented by the general formula (2) by forming a lactone ring on the acidic side, It is hardly soluble or insoluble in water. On the other hand, the polymer containing the structural unit represented by the general formula (2) is easily opened on the alkaline side to become a polymer containing the structural unit represented by the general formula (1), and is easily dissolved in water. It becomes soluble.

For this reason, it is presumed that the above-mentioned cement additive becomes a cement dispersant by opening the lactone ring when it is mixed with cement or a cement compound, and is uniformly mixed in the hardened cement. When the hardened cement containing the cement additive as a deterioration inhibitor of the hardened cement is exposed to an aqueous solution having a low pH such as acid rain, the polymer on the surface of the hardened cement is exposed to the polymer ( A polymer containing the structural unit represented by the general formula (1) and / or the structural unit represented by the general formula (2))
It is presumed that by forming a lactone ring and forming a film, the acid or acidic aqueous solution becomes impermeable.

On the other hand, a conventional hardened cement material containing a deterioration inhibitor of a hardened cement material can be used for a long time in an acidic aqueous solution such as acid rain because the hardening material contains a water-soluble polymer. When exposed, the acid or acidic aqueous solution permeates into the hardened cement and deteriorates.

As described above, the cement additive of the present invention and the cement composition containing the cement additive are excellent in acid resistance and can sufficiently suppress deterioration such as neutralization of the hardened cement. . Therefore, according to the present invention, it is possible to provide a hardened cement material which is excellent in acid resistance and in which deterioration such as neutralization is suppressed.

[0068]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 130 g (1 mol) of ethyl α- (hydroxymethyl) acrylate as a hydroxyl group-containing monomer was placed in a 1000 ml four-necked flask equipped with a stirrer, a cooler, a nitrogen gas inlet tube and the like. And 300 ml of benzene as a solvent were charged, and ethyl α- (hydroxymethyl) acrylate was dissolved in the benzene to prepare a reaction solution.

Next, the above reaction solution was heated in an oil bath maintained at 65 ° C. while nitrogen was blown into the above four-necked flask. Thereafter, 1.3 g of azoisobutyronitrile (polymerization initiator) dissolved in a predetermined amount of benzene was added to the reaction solution to start a polymerization reaction.

Thirty minutes after the start of the polymerization reaction, an increase in the viscosity of the reaction solution was confirmed. After stirring the reaction solution for 3 hours, it was cooled to terminate the polymerization reaction. Thereafter, 400 g of a 10% aqueous sodium hydroxide solution as an alkaline substance was added to the above reaction solution, followed by stirring to hydrolyze the ester portion of the obtained polymer. Then, benzene and the by-produced ethanol were removed under reduced pressure to obtain an aqueous solution of sodium polyα- (hydroxymethyl) acrylate as a polymer having the structural unit represented by the general formula (1). . The weight average molecular weight (Mw) of sodium poly-α- (hydroxymethyl) acrylate in the aqueous solution measured by aqueous GPC (gel permeation chromatography) was 55,000 in terms of polyacrylic acid.

Next, the above-mentioned sodium poly-α- (hydroxymethyl) acrylate was kneaded with Portland cement, standard sand and water as the cement additive according to the present invention, and hardened to prepare a specimen. The neutralization depth of the specimen was measured.

The neutralization depth of the specimen was measured by the following method. That is, the test specimen was immersed in a 1% sulfuric acid aqueous solution for 4 days, taken out, washed with running water at a predetermined flow rate for a predetermined time, and then dried at 50 ° C. for 3 hours. Thereafter, the specimen was split and divided into two parts, and a 1% phenolphthalein-methanol solution was sprayed on the cross section to measure the neutralized thickness (thickness of the uncolored portion). And the depth.

The results are shown in Table 1 together with the composition of the cement composition for preparing the test specimen (the amount of each raw material). The amount of water in the cement composition is adjusted by adjusting the amount of water to be added according to the amount of water contained in the aqueous solution of sodium poly-α- (hydroxymethyl) acrylate. The content of water was adjusted to be 60% by weight of the cement weight.

[Examples 2 and 3] In Example 1, except that the composition of the cement composition was changed as shown in Table 1,
A sample was prepared by performing the same reaction and operation as in Example 1. The neutralization depth of the specimen was measured in the same manner as in Example 1. Table 1 shows the results together with the composition of the cement composition.

Example 4 130 g (1 mol) of ethyl α- (hydroxymethyl) acrylate as a hydroxyl group-containing monomer was placed in a 1000 ml four-necked flask equipped with a stirrer, a cooler, a nitrogen gas inlet tube and the like. And methyl methacrylate 2
1 g (0.2 mol) and 300 m of benzene as a solvent
l and α- (hydroxymethyl) is added to the benzene.
Ethyl acrylate and methyl methacrylate were dissolved to obtain a reaction solution.

Next, the above reaction solution was heated in an oil bath maintained at 65 ° C. while nitrogen was blown into the four-necked flask. Thereafter, 1.5 g of azoisobutyronitrile (polymerization initiator) dissolved in a predetermined amount of benzene was added to the reaction solution to start a polymerization reaction.

After 30 minutes from the start of the polymerization reaction, the increase in the viscosity of the reaction solution was confirmed. After the reaction solution was stirred for 5 hours, it was cooled to terminate the polymerization reaction. Thereafter, 480 g of a 10% aqueous sodium hydroxide solution as an alkaline substance was added to the above reaction solution, followed by stirring to hydrolyze the ester portion of the obtained polymer. Next, benzene and by-produced methanol and ethanol are removed under reduced pressure, and sodium poly-α- (hydroxymethyl) acrylate / methacrylic acid as a polymer having the structural unit represented by the general formula (1) An aqueous solution of a sodium copolymer was obtained. The weight average molecular weight (Mw) of the sodium poly (α- (hydroxymethyl) acrylate / sodium methacrylate) copolymer in the aqueous solution measured by aqueous GPC was 150,000, in terms of polyacrylic acid.
It was 0.

Next, the above-mentioned sodium poly-α- (hydroxymethyl) acrylate / sodium methacrylate copolymer was used as a cement additive according to the present invention in the same manner as in Example 1 to produce Portland cement, standard sand, And water and kneaded, and cured to prepare a specimen. The neutralization depth of the specimen was measured in the same manner as in Example 1. The results are shown in Table 1 together with the composition of the cement composition for preparing the specimen.

[Examples 5 and 6] In Example 4, except that the composition of the cement composition was changed as shown in Table 1,
A sample was prepared by performing the same reaction and operation as in Example 4. The neutralization depth of the specimen was measured in the same manner as in Example 1. Table 1 shows the results together with the composition of the cement composition.

Example 7 2000 ml of 1N hydrochloric acid aqueous solution
While stirring, the aqueous solution of sodium polyα- (hydroxymethyl) acrylate obtained in Example 1 was gradually added dropwise to the aqueous hydrochloric acid solution. As a result, a white solid was deposited. After filtering the white solid, dried under predetermined conditions,
A yield of 78 g of a white powder was obtained. PH of filtrate at this time
Was 2.

With respect to the white powder obtained as described above,
The substance was identified by elemental analysis and infrared absorption spectrum (IR) measurement. As a result, the above-mentioned white powder is a lactone cyclized product of poly α- (hydroxymethyl) acrylic acid, that is, the general formula (5)

[0083]

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The polymer (polylactone cyclized product) containing the structural unit represented by the following formula was confirmed.

FIG. 1 shows the infrared absorption spectrum of the white powder.
Shown in The calculated values of the elemental analysis are as follows. Theoretical value C 47.06%, H 5.88%, O 47.06% Measured value C 47.32%, H 5.66%, O 47.02% Then, the white powder (polylactone cyclized product) was obtained. A sample was prepared by kneading with Portland cement, standard sand, and water as the cement additive according to the present invention and curing the mixture. The neutralization depth of the specimen was measured in the same manner as in Example 1. The results are shown in Table 1 together with the composition of the cement composition for preparing the specimen.

[Examples 8 and 9] In Example 7, except that the composition of the cement composition was changed as shown in Table 1,
A sample was prepared by performing the same reaction and operation as in Example 7. The neutralization depth of the specimen was measured in the same manner as in Example 1. Table 1 shows the results together with the composition of the cement composition.

Example 10 2.5 g of the white powdery polylactone cyclized product obtained in Example 7 and 200 ml of anhydrous methanol were placed in a 500 ml four-necked flask equipped with a stirrer, a nitrogen gas inlet tube and the like. And the resulting mixture was stirred to disperse the cyclized product of polylactone in the anhydrous methanol. Next, in the four-necked flask,
8.5 g of sodium methoxide was added, and the mixture was stirred at room temperature for 2 hours. Then, the obtained slurry was filtered and dried under predetermined conditions to obtain 30 g of a white powder.

The white powder obtained as described above was
The substance was identified by elemental analysis and infrared absorption spectrum (IR) measurement. As a result, it was confirmed that the white powder obtained in this example was obtained by neutralizing the carboxylic acid portion of the polylactone cyclized product obtained in Example 7.

Next, the above-mentioned white powder obtained in this example was kneaded with Portland cement, standard sand, and water as additives for cement according to the present invention, and hardened to prepare a specimen. The neutralization depth of the specimen was measured in the same manner as in Example 1. The results are shown in Table 1 together with the composition of the cement composition for preparing the specimen.

[Examples 11 and 12] Specimens were prepared in the same manner as in Example 10, except that the composition of the cement composition was changed as shown in Table 1. The neutralization depth of the specimen was measured in the same manner as in Example 1. Table 1 shows the results together with the composition of the cement composition.

Comparative Example 1 A comparative specimen was prepared using a comparative cement composition comprising Portland cement, standard sand, and water. That is, a comparative specimen was prepared in the same manner as in Example 1 except that the cement additive of the present invention was not included. The neutralization depth of the comparative sample was measured in the same manner as in Example 1. The results are shown in Table 1 together with the composition of the comparative cement composition.

[0092]

[Table 1]

As is clear from the results shown in Table 1, it is understood that the use of the cement additive of the present invention suppresses the neutralization of the specimen (neutralization of concrete).

[0094]

As described above, the additive for cement according to claim 1 of the present invention has the general formula (1)

[0095]

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Wherein R ¹ represents a hydrogen atom or an organic residue, R ² represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group;
Or an integer of 2).

The additive for cement according to claim 2 of the present invention has the general formula (2)

[0098]

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(Wherein, R ³ represents a hydrogen atom or an organic residue, and R ⁴ represents a hydrogen atom, a methyl group or —CHR ⁶ OH
R ⁵ represents a hydrogen atom, a methyl group, —COOR
⁷ represents a phenyl group; R ⁶ represents a hydrogen atom or an organic residue; R ⁷ represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group; Or an integer of 2).

The additive for cement according to claim 3 of the present invention has the general formula (1)

[0101]

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Wherein R ¹ represents a hydrogen atom or an organic residue, R ² represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group;
Or an integer of 2) and a general formula (2)

[0103]

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(In the formula, R ³ represents a hydrogen atom or an organic residue, and R ⁴ represents a hydrogen atom, a methyl group or —CHR ⁶ OH
R ⁵ represents a hydrogen atom, a methyl group, —COOR
⁷ represents a phenyl group; R ⁶ represents a hydrogen atom or an organic residue; R ⁷ represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group; Or an integer of 2) in the same molecule.

According to the constitutions of claims 1 to 3, it is possible to provide an additive for cement which is excellent in acid resistance and can sufficiently suppress deterioration such as neutralization of a hardened cement. Play.

As described above, the cement composition according to the fourth aspect of the present invention is configured to include the cement additive according to any one of the first to third aspects and cement.

According to the above configuration, the additive for cement according to any one of claims 1 to 3 is excellent in acid resistance and can sufficiently suppress deterioration such as neutralization of the cured cement.
The cement composition containing the additive for cement also has excellent ability to suppress the deterioration of the hardened cement. Therefore, according to the above configuration, it is possible to provide a cement composition having excellent acid resistance and capable of sufficiently suppressing deterioration such as neutralization of a hardened cement product.

The hardened cement according to claim 5 of the present invention has a structure obtained by hardening the cement composition according to claim 4 as described above.

According to the above configuration, there is an effect that it is possible to provide a hardened cement material which is excellent in acid resistance and in which deterioration such as neutralization is suppressed.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of a white powder obtained in one example of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C07D 309/30 C07D 309/30 C04B 103: 60 111: 22

Claims (5)

[Claims] 1. A compound of the general formula (1) (Wherein, R ¹ represents a hydrogen atom or an organic residue, R ² represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group, and n is an integer of 0, 1 or 2) Which comprises a polymer containing a structural unit represented by the formula: 2. A compound of the general formula (2) (Wherein, R ³ represents a hydrogen atom or an organic residue; R ⁴ represents a hydrogen atom, a methyl group or a —CHR ⁶ OH group;
⁵ represents a hydrogen atom, a methyl group, a —COOR ⁷ group, or a phenyl group; R ⁶ represents a hydrogen atom or an organic residue; R ⁷ represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, an organic group; An additive for cement, comprising a polymer containing a structural unit represented by an amine group, and m represents an integer of 0, 1 or 2. 3. A compound of the general formula (1) (Wherein, R ¹ represents a hydrogen atom or an organic residue, R ² represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, or an organic amine group, and n is an integer of 0, 1 or 2) And a structural unit represented by the general formula (2): (Wherein, R ³ represents a hydrogen atom or an organic residue; R ⁴ represents a hydrogen atom, a methyl group or a —CHR ⁶ OH group;
⁵ represents a hydrogen atom, a methyl group, a —COOR ⁷ group, or a phenyl group; R ⁶ represents a hydrogen atom or an organic residue; R ⁷ represents a hydrogen atom, a monovalent metal ion, a divalent metal ion, an ammonium group, an organic group; An additive for cement comprising a polymer containing, in the same molecule, a structural unit represented by an amine group and m represents an integer of 0, 1 or 2. 4. A cement composition comprising the cement additive according to any one of claims 1 to 3 and cement. 5. A cured cement obtained by curing the cement composition according to claim 4.