JP7820190B2 - Cement dispersant - Google Patents

Description

The present invention relates to a cement dispersant that has excellent water-reducing and slump-retaining properties and can fully demonstrate these properties regardless of the usage environment.

In order to ensure the fluidity of cement mixtures such as concrete, high-range water-reducing agents, such as polycarboxylic acid polymers, have recently become widely used as admixtures that combine high water-reducing performance with the effect of reducing slump loss. While the original feature of high-range water-reducing agents is that they exhibit water-reducing performance superior to that of conventional cement dispersants, they also have the advantage of being able to reduce slump loss without having much effect on the setting delay of concrete when used in the appropriate amount, and this performance, which is not seen in other agents, is also important.
Examples of dispersants using the polycarboxylic acid polymer include the following cement dispersants using a copolymer containing a polyalkylene glycol alkenyl ether monomer and an unsaturated carboxylic acid monomer as essential components: a cement dispersant mainly composed of a copolymer derived from a polyethylene glycol monoallyl ether monomer (I), a maleic acid monomer (II), and a monomer (III) copolymerizable with these monomers in a specific ratio (Patent Document 1); a cement dispersant mainly composed of a copolymer obtained by copolymerizing an unsaturated polyalkylene glycol ether monomer (I), a maleic acid monomer (II), and another monomer (III) copolymerizable with these monomers in a specific copolymerization ratio (Patent Document 2); and a cement dispersant consisting of a short-chain polyalkylene glycol alkenyl ether monomer and an unsaturated carboxylic acid monomer. Cement dispersants containing two types of copolymers as essential components: copolymer (A) and copolymer (B) consisting of a long-chain polyalkylene glycol alkenyl ether monomer and an unsaturated carboxylic acid monomer (Patent Document 3); amino group-containing polymers that can be used as cement dispersants, obtained by copolymerization of unsaturated carboxylic acid monomers and/or unsaturated acid anhydride monomers and unsaturated alcohol monomers, some of which have amino groups introduced therein (Patent Document 4); unsaturated alcohol alkylene oxide adduct polymers consisting of unsaturated monomers containing nitrogen atoms, unsaturated alcohol alkylene oxides, and unsaturated carboxylic acid monomers that can be suitably used as cement admixtures for ultra-high strength concrete (Patent Document 5); and cement dispersants containing polycarboxylic acid polymers containing structural units derived from fumaric acid as the unsaturated carboxylic acid monomer (Patent Document 6).

Special Publication No. 58-38380 Japanese Patent Application Publication No. 10-236858 Japanese Patent Application Laid-Open No. 2001-302306 Japanese Patent Application Laid-Open No. 2003-192722 Japanese Patent Application Laid-Open No. 2003-327644 Patent No. 4984254

Thus, many copolymers have been studied and proposed as cement dispersants, and development of agents with even better performance in water reduction, retention and concrete viscosity is underway.
On the other hand, the performance of cement dispersants, including their water-reducing properties, can fluctuate sensitively depending on changes in concrete mix such as cement type and water/cement ratio, as well as changes in cement mixing and construction temperatures, and there are occasional cases where these changes in the usage environment make it difficult to use dispersants that have been improved in various ways.
Therefore, there was a need to develop a dispersant polymer that could fully demonstrate its performance even when the application environment, such as cement type, concrete mix, and operating temperature, changed, and that could be used widely in a variety of environments.

The present invention was made in light of this conventional technical background in order to improve the performance of cement dispersants. Its objective is to provide a cement dispersant that can fully demonstrate its performance as a cement dispersant even when the cement type, concrete mix, temperature environment, etc. are changed, can be used in a wide variety of environments, and is easy to work with.

After extensive research, the inventors discovered that in a polycarboxylic acid polymer comprising a reactive alcohol derivative having a polymerizable bond site, an unsaturated carboxylic acid compound, and an unsaturated dicarboxylic acid ester compound, by using an unsaturated dicarboxylic acid as the unsaturated carboxylic acid compound in combination with an ester having a monoester:diester mass ratio of 10:90 to 25:75 as the unsaturated dicarboxylic acid ester, the performance of the cement dispersant can be fully demonstrated even when the cement type, concrete mix, temperature environment, etc. are changed, resulting in a cement dispersant that can be used widely in a variety of environments.

That is, the present invention provides a cement dispersant comprising a polycarboxylic acid polymer comprising a structural unit derived from a polyalkylene glycol alkenyl ether compound, a structural unit derived from an unsaturated carboxylic acid compound, and a structural unit derived from an unsaturated dicarboxylic acid ester compound,
the content ratio of the structural units derived from the unsaturated dicarboxylic acid is 50 to 100% by mass relative to the total mass of the structural units derived from the unsaturated carboxylic acid compound, and
The present invention relates to a cement dispersant, characterized in that the ratio of the structural units derived from the unsaturated dicarboxylic acid ester compound to the structural units derived from the unsaturated dicarboxylic acid monoester compound is 10:90 to 25:75 by mass.
In a preferred embodiment, the ratio of the structural units derived from the unsaturated carboxylic acid compound to the structural units derived from the unsaturated dicarboxylic acid ester compound can be, in mass ratio, 1 to 50 mass%:99 to 50 mass% of the structural units derived from the unsaturated carboxylic acid compound:the structural units derived from the unsaturated dicarboxylic acid ester compound.

The present invention also provides a polycarboxylic acid polymer, wherein the polycarboxylic acid polymer comprises the following structural units (I), (II), (IIIa), and (IIIb):
The content of the structural unit (IIa) derived from the following unsaturated dicarboxylic acid is 50 to 100% by mass relative to the total mass of the following structural unit (II), and
The present invention relates to a cement dispersant characterized in that the ratio of the structural unit (IIIa) to the structural unit (IIIb) is 10:90 to 25:75 by mass.
In a preferred embodiment, the ratio of the following structural unit (II), the following structural unit (IIIa), and the following structural unit (IIIb) can be, in mass ratio, structural unit (II):[structural unit (IIIa)+structural unit (IIIb)]=1 to 50 mass%:99 to 50 mass%.
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, X represents —(CH ₂ )bO—, AO represents an alkylene oxide group having 2 to 4 carbon atoms, a represents the average number of moles of alkylene oxide added and is a number from 1 to 200, and b represents an integer from 1 to 20.)
(In the formula, ^R5 to ^R8 each independently represent a hydrogen atom, a hydrocarbon group having 1 to 22 carbon atoms, or ^-COOM1 , provided that at least one of ^R5 to ^R8 represents ^-COOM1 , and that parts of two of the groups ^R5 to ^R8 can combine to form an acid anhydride. ^M1 represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an alkanolamine.)
(In the formula, ^R5 and ^R6 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, and ^M2 and ^M3 each independently represent a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an alkanolamine.)
(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms; M ⁴ represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an alkanolamine; Y represents a hydrocarbon group having 1 to 22 carbon atoms or -(AO)c-R ¹¹ , where AO represents an alkylene oxide group having 2 to 4 carbon atoms, c represents the average number of moles of alkylene oxide added and is a number from 1 to 200; and R ¹¹ represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms.)
(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms; Y represents a hydrocarbon group having 1 to 22 carbon atoms or -(AO)c-R ¹¹ , where AO represents an alkylene oxide group having 2 to 4 carbon atoms; c represents the average number of moles of alkylene oxide added and is a number from 1 to 200; and R ¹¹ represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms.)

Furthermore, the present invention relates to a method for producing a polycarboxylic acid polymer, which further comprises the following structural unit (I) in addition to the structural unit (I), the structural unit (II), the structural unit (IIIa) and the structural unit (IIIb):
V).
(In the formula, Z represents a group bonded via an amide bond to a carbon atom in the main chain of a polyamidepolyamine obtained by condensing a dibasic acid with a polyalkylenepolyamine and/or a modified polyamidepolyamine obtained by adding 0.1 to 10 moles of an alkylene oxide having 2 to 4 carbon atoms per equivalent of the active imino group, amino group, or amide residue of the polyamidepolyamine.)

The present invention also relates to a cement dispersant that contains, in addition to the polycarboxylic acid polymer, a polyamidepolyamine obtained by condensing a dibasic acid with a polyalkylenepolyamine, and/or a modified polyamidepolyamine obtained by adding 0.1 to 10 moles of alkylene oxide having 2 to 4 carbon atoms per equivalent of the active imino group, amino group, or amide residue of the polyamidepolyamine.

The present invention provides a cement dispersant that has excellent water-reducing and slump-retaining properties, and can fully demonstrate these properties even when the cement type, concrete mix, or temperature environment changes, making it possible to provide a cement dispersant that can be widely used in a variety of environments.

FIG. 1 is a diagram showing an HPLC chart of the unsaturated dicarboxylic acid ester compound (D6) prepared in Production Example 3.

The present invention relates to a cement dispersant comprising a polycarboxylic acid polymer comprising structural units derived from a polyalkylene glycol alkenyl ether compound, structural units derived from an unsaturated carboxylic acid compound, and structural units derived from an unsaturated dicarboxylic acid ester compound, wherein the content of the structural units derived from the unsaturated dicarboxylic acid is 50 to 100% by mass relative to the total mass of the structural units derived from the unsaturated carboxylic acid compound, and the ratio of the structural units derived from the unsaturated dicarboxylic acid ester compound to the structural units derived from the unsaturated dicarboxylic acid monoester compound is 10:90 to 25:75 by mass. More specifically, the polycarboxylic acid polymer comprises the structural units (I), (II), (IIIa), and (IIIb) shown above. Furthermore, the polycarboxylic acid polymer may comprise, in addition to the structural units (I), (II), (IIIa), and (IIIb), the structural unit (IV) derived from a polyamidepolyamine and/or a modified polyamidepolyamine. The polycarboxylic acid polymer thus constructed has a comb polymer structure in which graft chains such as polyalkylene oxide chains and polyamide polyamine chains are bonded to the main chain skeleton.
The cement dispersant of the present invention may contain, in addition to the polycarboxylic acid polymer, a polyamide polyamine and/or a modified polyamide polyamine.
The present invention will be described in detail below.

[Structural unit (I), structural unit (II), structural unit (IIIa) and structural unit (IIIb)]
The structural unit (I) constituting the polycarboxylic acid polymer which is the cement dispersant of the present invention is represented by the following formula:
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, X represents —(CH ₂ )bO—, AO represents an alkylene oxide group having 2 to 4 carbon atoms, a represents the average number of moles of alkylene oxide added and is a number from 1 to 200, and b represents an integer from 1 to 20.)

In the above formula, AO is preferably composed of ethylene oxide having 2 carbon atoms or two or more alkylene oxides, and in this case, either block addition or random addition may be used.
When two or more alkylene oxides are used, it is preferable that alkylene oxides having 3 or 4 carbon atoms account for 0.1 to less than 30 mol% of the average number of moles of alkylene oxide added represented by a. In particular, it is desirable to arrange 0.1 to less than 20 mol% of the alkylene oxides having 3 or 4 carbon atoms on the terminal side of the alkylene oxide chain (bonding position with ^R4 ) from the viewpoint of improving performance aspects such as water reducing ability, retention, and concrete viscosity.

Furthermore, in the above formula, ^R4 is particularly preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms (such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, or a phenyl group).

The structural unit (I) is a structural unit derived from a polyalkylene glycol alkenyl ether compound, for example, a structural unit derived from the following compounds: alkenyl ethers formed from (alkoxy)polyalkylene glycols and alkenyl ethers having 3 to 8 carbon atoms, such as polyalkylene glycol monoallyl ether, polyalkylene glycol monoalkenyl ether, methoxypolyalkylene glycol monoallyl ether, and methoxypolyalkylene glycol monoalkenyl ether; and unsaturated aliphatic ethers which are alkylene oxide adducts of unsaturated aliphatic alcohols. Specific examples include alkylene oxide adducts of 3-methyl-3-buten-1-ol, alkylene oxide adducts of 2-propen-1-ol (allyl alcohol), and ethers thereof. Of these, the most preferred specific example of the compound is the alkylene oxide adduct of 3-methyl-3-buten-1-ol.
The structural unit (I) may be derived from one of these compounds alone or from a combination of two or more of them.

The structural unit (II) constituting the polycarboxylic acid polymer which is the cement dispersant of the present invention is represented by the following formula:
(In the formula, R ⁵ to R ⁸ each independently represent a hydrogen atom, a hydrocarbon group having 1 to 22 carbon atoms, or —COOM ¹ , provided that at least one of R ⁵ to R ⁸ represents —COOM ¹ ;
Furthermore, two groups among ^R5 to ^R8 may combine together to form an acid anhydride. ^M1 represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an alkanolamine.

The structural unit (II) is a structural unit derived from an unsaturated carboxylic acid compound, such as (meth)acrylic acid and its salts, or a structural unit derived from fumaric acid, maleic acid, maleic anhydride, etc. In a preferred embodiment, the structural unit (II) is a structural unit derived from an unsaturated dicarboxylic acid such as fumaric acid, maleic acid, or maleic anhydride, and in particular, the structural unit (II) contains at least a portion of a structural unit (IIa) derived from an unsaturated dicarboxylic acid. In this specification, the term "(meth)acrylic acid" refers to both methacrylic acid and acrylic acid.
(In the formula, ^R5 and ^R6 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, and ^M2 and ^M3 each independently represent a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an alkanolamine.)
In the structural unit (II) and the structural unit (IIa), the partial structure (-COOM ¹ , -COOM ² , -COOM ³ ) derived from carboxylic acid may be in the form of either a carboxy group (-COOH: acid form) or a salt of a carboxy group (neutralized form), or these forms may be mixed, but the partially neutralized or completely neutralized form is preferred as the product form.

In the present invention, the content of structural unit (IIa) derived from unsaturated dicarboxylic acid is preferably 50 to 100% by mass, preferably 60 to 100% by mass, and more preferably 70 to 100% by mass, based on the total mass of the structural unit (II), in terms of water reducing properties and slump retention.

The structural units (IIIa) and (IIIb) constituting the polycarboxylic acid polymer serving as the cement dispersant of the present invention are represented by the following formula: The present invention is characterized in that the ratio of the structural unit (IIIa) to the structural unit (IIIb) is 10:90 to 25:75 by mass.
(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms; M ⁴ represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an alkanolamine; Y represents a hydrocarbon group having 1 to 22 carbon atoms or -(AO)c-R ¹¹ , where AO represents an alkylene oxide group having 2 to 4 carbon atoms, c represents the average number of moles of alkylene oxide added and is a number from 1 to 200; and R ¹¹ represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms.)
(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms; Y represents a hydrocarbon group having 1 to 22 carbon atoms or -(AO)c-R ¹¹ , where AO represents an alkylene oxide group having 2 to 4 carbon atoms; c represents the average number of moles of alkylene oxide added and is a number from 1 to 200; and R ¹¹ represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms.)

In the structural unit (IIIa), the partial structure (-COOM ⁴ ) derived from a carboxylic acid may be in the form of either a carboxy group (-COOH: acid form) or a salt of a carboxy group (neutralized form), or these forms may be mixed, but a partially neutralized or completely neutralized form is preferred as a product form.

Specific examples of Y in the structural units (IIIa) and (IIIb) include partial or full esters of carbon atoms having 1 to 22, partial or full esters of polyalkylene oxide adducts, and partial or full esters of alkoxypolyalkylene glycols. Alkylene oxides can be added singly or in combination, and when two or more alkylene oxides are used, they may be added in either a block or random manner.

The structural unit (IIIa) and the structural unit (IIIb) are structural units derived from an unsaturated dicarboxylic acid ester compound, and specifically, structural units derived from methoxypolyethylene glycol monofumarate, methoxypolypropylene glycol monofumarate, methoxypolyethylene polypropylene glycol monofumarate, methoxypolyethylene glycol difumarate, methoxypolypropylene glycol difumarate, methoxypolyethylene polypropylene glycol difumarate, methoxypolyethylene glycol monomaleate, methoxypolypropylene glycol monomaleate, methoxypolyethylene polypropylene glycol monomaleate, methoxypolyethylene glycol dimaleate, methoxypolypropylene glycol dimaleate, methoxypolyethylene polypropylene glycol dimaleate, etc.
Among the structural units (IIIa) and (IIIb), structural units derived from fumaric acid ester compounds, specifically structural units derived from methoxypolyethylene glycol monofumarate, methoxypolypropylene glycol monofumarate, methoxypolyethylene polypropylene glycol monofumarate, methoxypolyethylene glycol difumarate, methoxypolypropylene glycol difumarate, and methoxypolyethylene polypropylene glycol difumarate, are particularly preferred in terms of water reducing ability and slump retention.

The mass ratio of the structural unit (II) to the sum of the structural unit (IIIa) and the structural unit (IIIb) can be, for example, structural unit (II):[structural unit (IIIa)+structural unit (IIIb)]=1 to 50% by mass:99 to 50% by mass, preferably 1 to 40% by mass:99 to 60% by mass, more preferably 1 to 30% by mass:99 to 70% by mass, for example, 10 to 20% by mass:90 to 80% by mass.
If the structural unit derived from the unsaturated dicarboxylic acid ester [structural unit (IIIa) + structural unit (IIIb)] is smaller than the above range, slump and stability of viscosity over time may not be obtained.

[Structural unit (IV)]
Furthermore, the polycarboxylic acid polymer serving as the cement dispersant of the present invention may also contain a structural unit (IV) represented by the following formula, in addition to the structural unit (I), the structural unit (II), the structural unit (IIIa), and the structural unit (IIIb).
(In the formula, Z represents a group bonded via an amide bond to a carbon atom in the main chain of a polyamidepolyamine obtained by condensing a dibasic acid with a polyalkylenepolyamine and/or a modified polyamidepolyamine obtained by adding 0.1 to 10 moles of an alkylene oxide having 2 to 4 carbon atoms per equivalent of the active imino group, amino group, or amide residue of the polyamidepolyamine.)

In the structural unit (IV), the dibasic acid constituting Z includes aliphatic saturated dibasic acids having a total of 2 to 10 carbon atoms, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. The polyalkylene polyamine constituting Z includes ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, and mixtures of high molecular weight polyethylene polyamines containing many ethylene units and nitrogen atoms.

The structural unit (IV) is a structural unit formed by bonding, via an amide bond, polyamidepolyamine, which is a condensation product of such a dibasic acid and polyalkylenepolyamine, and/or a modified polyamidepolyamine in which 0.1 to 10 moles of alkylene oxide having 2 to 4 carbon atoms are added to 1 equivalent of the active imino group, amino group, or amide residue of the polyamidepolyamine, with maleic anhydride, maleic acid, or fumaric acid.
Some of these polyamide polyamines or polyalkylene oxide-modified polyamide polyamines have the property of exhibiting basicity in aqueous solution, and therefore may act as a neutralizing agent for polycarboxylic acid polymers.

[Composition ratio of each structural unit]
In the polycarboxylic acid polymer comprising the structural units (I), (II), (IIIa), and (IIIb), the proportions thereof are, for example, structural unit (I):structural unit (II):[structural unit (IIIa)+structural unit (IIIb)]=80 to 10% by mass:1 to 30% by mass:10 to 90% by mass, and preferably structural unit (I):structural unit (II):[structural unit (IIIa)+structural unit (IIIb)]=70 to 10% by mass:1 to 20% by mass:20 to 80% by mass.
In addition, in a polycarboxylic acid polymer comprising the structural unit (I), the structural unit (II), the structural unit (IIIa), the structural unit (IIIb), and the structural unit (IV), for example, the structural unit (I):structural unit (II):[structural unit (IIIa) + structural unit (IIIb)]:structural unit (IV)=80 to 10% by mass:1 to 30% by mass:10 to 90% by mass:1 to 10% by mass, and preferably the structural unit (I):structural unit (II):[structural unit (IIIa) + structural unit (IIIb)]=70 to 10% by mass:1 to 20% by mass:20 to 80% by mass:2 to 7% by mass (However, the total of the structural unit (I), the structural unit (II), the structural unit (IIIa) and the structural unit (IIIb), or the total of the structural unit (I), the structural unit (II), the structural unit (IIIa), the structural unit (IIIb) and the structural unit (IV) is 100% by mass.)
In any of the above-mentioned composition ratios, it is desirable for the present invention to be suitably implemented such that the structural unit (II): [structural unit (IIIa) + structural unit (IIIb)] = 1 to 60 mol %: 99 to 40 mol %.

[Other structural units (V) that may be contained]
The above-mentioned polycarboxylic acid polymer may contain the structural unit (V) in addition to the structural unit (I), the structural unit (II), the structural unit (IIIa), the structural unit (IIIb) and the structural unit (IV).
Other compounds from which the structural unit (V) may be contained include methoxypolyethylene glycol mono(meth)acrylate, methoxypolypropylene glycol mono(meth)acrylate, methoxypolyethylenepolypropylene glycol mono(meth)acrylate, vinyl sulfonic acid (salt), (meth)allyl sulfonic acid (salt), (meth)acrylamidomethyl sulfonic acid, (meth)acrylamidoethyl sulfonic acid, 2-methylpropanesulfonic acid (meth)acrylamide, styrene sulfonic acid (salt), alkyl (meth)acrylate, styrene, (meth)acrylate ... The compounds are exemplified as monomers for conventional polycarboxylic acid cement dispersants, such as (meth)acrylamide, and unsaturated monomers having a phosphate group, such as 2-(meth)acryloyloxyethyl acid phosphate, 3-(meth)acryloyloxypropyl acid phosphate, (meth)acryloyloxypolyoxyethylene glycol acid phosphate, and (meth)acryloyloxypolyoxypropylene glycol acid phosphate, and the type of the compound is not particularly limited as long as it can form a polymer with the structural units (I) to (IV). In particular, incorporating a structural unit derived from an alkali-hydrolyzable compound to impart slump retention to the polycarboxylic acid polymer is one of the means that can be easily conceived in combination with Japanese Patent No. 3780465, etc.
The structural unit (V) preferably has a composition ratio of the polycarboxylic acid polymer, etc. [structural unit (I) + structural unit (II) + structural unit (IIIa) + structural unit (IIIb) + structural unit (IV)]:structural unit (V) = 100 to 70% by mass: 0 to 30% by mass (however, the total is 100% by mass).

[Polyamidepolyamine and/or modified polyamidepolyamine]
In terms of improving concrete viscosity, the cement dispersant of the present invention preferably contains, in addition to the above-mentioned polycarboxylic acid polymer, a polyamidepolyamine obtained by condensing a dibasic acid with a polyalkylenepolyamine and/or a modified polyamidepolyamine obtained by adding 0.1 to 10 moles of alkylene oxide having 2 to 4 carbon atoms per equivalent of the active imino group, amino group, or amide residue of the polyamidepolyamine.
The content ratio of these polyamidepolyamines and/or modified polyamidepolyamines is preferably in the range of polycarboxylic acid polymer: polyamidepolyamine and/or modified polyamidepolyamine=98 to 90% by mass:2 to 10% by mass.

Examples of polyalkylene polyamines constituting the polyamide polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, and mixtures of high molecular weight polyethylene polyamines containing a large amount of ethylene units and nitrogen atoms; polymers of cyclic imines such as polyethyleneimine, polypropyleneimine, poly-3-methylpropylimine, and poly-2-ethylpropylimine; and polymers of unsaturated amines such as polyvinylamine and polyallylamine. Furthermore, the polyalkylene polyamine may be a copolymer of a cyclic imine such as ethyleneimine, propyleneimine, 3-methylpropylimine, or 2-ethylpropylimine, or an unsaturated amide or imide such as N-vinylacetamide, N-vinylformamide, or N-vinylphthalimide, and an unsaturated compound copolymerizable therewith. Examples of unsaturated compounds copolymerizable with cyclic imines, unsaturated amides, unsaturated imides, and the like include, for example, dimethylacrylamide, styrene, methyl acrylate, methyl methacrylate,
Examples of the alkyl group include acrylic acid, methacrylic acid, styrenesulfonic acid, and salts thereof; cyclic sulfide compounds such as ethylene sulfide and propylene sulfide; cyclic ethers such as oxetane, mono- or bis-alkyloxetane, mono- or bis-alkylchloromethyloxetane, tetrahydrofuran, and mono- or bis-alkyltetrafluorofuran; cyclic formals such as 1,2-dioxofuran and trioxofuran; and N-substituted alkylimines such as N-methylethyleneimine.

Examples of dibasic acids constituting the polyamide polyamine include aliphatic saturated dibasic acids having a total of 2 to 10 carbon atoms, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.
Dibasic acids may also be used as derivatives thereof, such as dibasic acid anhydrides (e.g., anhydrides of the above dibasic acids), dibasic acid esters (e.g., monomethyl esters, monoethyl esters, monobutyl esters, monopropyl esters, dimethyl esters, diethyl esters, dibutyl esters, dipropyl esters, etc. of the above dibasic acids), or dibasic acid dihalides (dichlorides, dibromides, diiodides, etc. of the above dibasic acids).

The above-mentioned modified polyamidepolyamine refers to a compound in which 0.1 to 10 moles of alkylene oxide having 2 to 4 carbon atoms are added to one equivalent of the active imino group, amino group, or amide residue of the above-mentioned polyamidepolyamine. Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide, which can be used alone or in combination. When two or more alkylene oxides are used, they may be polymerized in either a block or random configuration.

[Method of producing each structural unit and polycarboxylic acid polymer]
In obtaining the polycarboxylic acid polymer that is the cement dispersant of the present invention, the method for producing the polyalkylene glycol alkenyl ether compound from which the structural unit (I) is derived and the polymerization method for obtaining the polycarboxylic acid polymer are not particularly limited.
However, in the alkylene oxide addition reaction during the production of the polyalkylene glycol alkenyl ether compound, it is necessary to carry out the production while taking into consideration that the polymerization active group (unsaturated group) does not lose its polymerization activity, that the position of the polymerization active group is not transferred, and that the amount of diol produced as a by-product is reduced. Note that these polyalkylene oxide adducts of alcohols having polymerization active groups can be used as polymerization raw materials regardless of whether or not they are purified after production.
In the method for producing a polycarboxylic acid polymer, a similar polymer can be obtained by any of solvent polymerization, aqueous solution polymerization, continuous polymerization, and batch polymerization. However, since it is necessary to pay attention to the solubility of the compound to be subjected to copolymerization, aqueous solution polymerization is generally used.

Methods for producing structural unit (IV) include, according to the usual amide method, condensing a dibasic acid with a polyamidepolyamine, then forming an amide group with maleic acid, fumaric acid, or maleic anhydride, and optionally adding an alkylene oxide; forming a condensate of a dibasic acid with a polyamidepolyamine or an alkylene oxide-modified polyamidepolyamine by adding an alkylene oxide, and then grafting the resulting polyamidepolyamine onto a polycarboxylic acid polymer; and adding an alkylene oxide to an aqueous solution of the resulting polyamidepolyamine, which has been grafted onto a polycarboxylic acid polymer.

The polycarboxylic acid polymer finally obtained as the cement dispersant of the present invention preferably has a weight-average molecular weight (measured by gel permeation chromatography (hereinafter referred to as "GPC"), calculated as polyethylene glycol) in the range of 10,000 to 500,000; if the weight-average molecular weight is outside this range, the water-reducing ability will be significantly reduced or the desired slump loss reduction effect will not be achieved. A weight-average molecular weight in the range of 10,000 to 100,000 is more preferable in order to further enhance the water-reducing ability. Furthermore, while the molecular weight can be controlled by adjusting the type and/or amount of radical polymerization initiator, etc. used in aqueous solution polymerization, the molecular weight distribution can also be controlled by using a chain transfer agent, etc. in combination.
In the present invention, the term "polymer" may refer only to the polymer itself, or may be broadly defined to include components including unreacted components and by-products generated in each polymerization step, alkylene oxide addition step, etc.

[Cement admixtures and additives that can be used in combination]
The cement dispersant of the present invention can be used in combination with suitable known admixtures in accordance with various concrete production conditions to form a cement admixture, specifically cement dispersants other than the cement dispersant of the present invention, air entraining agents, setting retarders, accelerators, separation reducing agents, thickeners, antifoaming agents, shrinkage reducing agents, etc.
The cement dispersant comprising the polycarboxylic acid polymer of the present invention includes both a form in which a publicly known and publicly used admixture is blended with the above-mentioned polycarboxylic acid polymer to form a cement admixture, and a form in which the above-mentioned polycarboxylic acid polymer and a publicly known and publicly used admixture are added separately during concrete production and then finally mixed in concrete. Examples of publicly known and publicly used admixtures are given below.

Generally, cement dispersants are used in appropriate combinations depending on the manufacturing conditions and performance requirements of concrete, etc. The same is true for the cement dispersant of the present invention, which is used alone as a cement dispersant or as a main agent, but can also be used as a modifier aid for cement dispersants with large slump loss, or in combination with cement dispersants with high initial water reduction properties.
Known cement dispersants other than those of the present invention include, in addition to the above-mentioned Patent Document 1, salts of polycarboxylic acid copolymers such as those disclosed in Japanese Patent Publication No. 59-18338, Japanese Patent No. 2628486, Japanese Patent No. 2774445, Japanese Patent No. 3235002, Japanese Patent No. 3336456, and Japanese Patent No. 3780456, as well as salts of naphthalenesulfonic acid-formalin condensates, salts of melaminesulfonic acid-formalin condensates, lignin sulfonates, sodium gluconate, and sugar alcohols. The blending ratio of the cement dispersant of the present invention to a cement dispersant other than that of the present invention is 1:99 to 99:1 mass%.

Specific examples of air entraining agents include <1> anionic air entraining agents, <2> nonionic air entraining agents, and <3> amphoteric air entraining agents. <1> Anionic air entraining agents include sulfate ester salts of higher alcohols (or their alkylene oxide adducts), alkylbenzene sulfonates, resin soap salts such as rosin soap, and phosphate ester salts of higher alcohols (or their alkylene oxide adducts). <2> Nonionic air entraining agents include alkylene glycols, alkylene oxide adducts of higher alcohols, esters of fatty acids and alkylene glycols, and alkylene glycol adducts of sugar alcohols. <3> Amphoteric air entraining agents consisting of anions and cations include alkyl betaines, alkylamido betaines, and amino acid-based amphoteric surfactants. The preferred amount of the air entraining agent added is 0.001 to 0.03% by mass of the cement dispersant.

Examples of setting retarders include: <1> inorganic setting retarders: phosphates, silicofluorides, zinc oxide, zinc carbonate, zinc chloride, zinc monoxide, copper hydroxide, magnesia salts, borax, and boron oxide; <2> organic setting retarders: phosphonic derivatives, sugars and their derivatives, oxycarboxylates, and lignin sulfonates; more specific examples include phosphonic derivatives: aminotri(methylenephosphonic acid), aminotri(methylenephosphonic acid) pentasodium salt, 1-hydroxyethylidene-1,1-diphosphonic acid, diethylenetriaminepenta(methylenephosphonic acid) and alkali metal salts, alkaline earth metal salts of phosphonic acid and its derivatives; sugars: sucrose, maltose, raffinose, lactose, glucose, and fructose;
Examples of suitable retarders include mannose, arabinose, xylose, avitose, lipose, and oxycarboxylates: gluconic acid, citric acid, glucoheptonic acid, malic acid, tartaric acid, and alkali metal and alkaline earth metal salts thereof. The preferred amount of the retarder to be added is 0.01 to 1.5% by mass based on the mass of the cement or other bonding material.

Examples of accelerators include inorganic accelerators such as calcium chloride and calcium nitrite, and organic accelerators such as alkanolamines. The preferred amount of accelerator added is 0.5 to 5% by mass of the cement or other bonding material.

Examples of thickeners and separation-reducing agents include: <1> cellulose-based water-soluble polymers: cellulose ether (MC, etc.), <2> polyacrylamide-based water-soluble polymers: polyacrylamide, <3> biopolymers: curdlan, welan gum, <4> non-ionic thickeners: polyalkylene glycol fatty acid diesters, polyalkylene glycol urethane condensates, etc. The preferred blend ratio of this thickener and separation-reducing agent to the concrete composition is 0.01 to 0.5% by mass.

Examples of antifoaming agents include nonionic antifoaming agents such as aliphatic alcohol alkylene oxide adducts, fatty acid alkylene oxide adducts, alkylene oxide difatty acid esters, polyhydric alcohol alkylene oxide adducts, and polyalkylene polyamine alkylene oxide adducts; silicone antifoaming agents made with silicone oil as an emulsion; higher alcohols made with higher alcohol as an emulsion; and mixtures containing these as the main components. The preferred amount of this antifoaming agent to be added is 0.01 to 1% by mass of the cement dispersant.

Examples of shrinkage-reducing agents include polyalkylene glycols, lower alcohol alkylene oxide adducts, and emulsions of these oil-based compounds. The preferred amount added is 0.1 to 5% by mass of the cement or other bonding material.

The amount of cement dispersant added varies depending on the mix conditions, including the concrete ingredients, but is typically added at approximately 0.05 to 5.0 mass% solids relative to the mass of cement. While a higher amount is better for achieving water reducibility and slump flow retention, adding too much can delay setting and, in some cases, cause poor hardening. The method of use is similar to that of general cement dispersants: either added undiluted during concrete mixing or diluted in mixing water beforehand. Alternatively, the dispersant may be added after mixing the concrete or mortar and then mixed uniformly again. The components other than the cement dispersant are conventional concrete components, including cement (e.g., ordinary Portland cement, high-early-strength Portland cement, low-heat/moderate-heat Portland cement, or blast-furnace cement), aggregate (i.e., fine and coarse aggregate), admixtures (e.g., silica fume, calcium carbonate powder, blast-furnace slag powder), expansive agents, and water. In addition to the cement dispersant of the present invention, other admixtures that can be added separately during mixing include the above-mentioned publicly known and commonly used air entraining agents, setting retarders, accelerators, separation reducing agents, thickeners, antifoaming agents, shrinkage reducing agents, etc., and these can also be added as appropriate. The proportions of each component can be determined appropriately depending on the type of component selected and the intended use.

The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples, as it is obtained by the above-described production method.
Unless otherwise specified, the percentages shown below represent mass percentages.

[Production Example 1: Preparation of Methanol Alkylene Oxide Adduct]
A stainless steel high-pressure reactor equipped with a thermometer, a stirrer, a pressure gauge, and a nitrogen inlet tube was charged with 70 g of methanol and 0.45 g of a 28% sodium methylate methanol solution, the atmosphere inside the reactor was replaced with nitrogen, and the reactor was heated to 150°C under a nitrogen atmosphere. While maintaining the temperature at 150°C under a safe pressure, 867 g of ethylene oxide was introduced into the reactor over 5 hours, and the temperature was then maintained for 1 hour to complete the alkylene oxide addition reaction, thereby obtaining a methanol alkylene oxide adduct (number of moles of EO added: 9 moles).

[Production Example 2: Preparation of unsaturated dicarboxylic acid ester compound (D1)]
A reaction vessel equipped with a thermometer, a stirrer, a nitrogen inlet tube, a condenser, and a sample tube was charged with 854 g of the methanol alkylene oxide adduct obtained in Production Example 1, 146 g of fumaric acid, and 10 g of paratoluenesulfonic acid, and the temperature was raised to 160°C. The reaction was then carried out for 10 hours while introducing nitrogen from the bottom at a rate of 5 ^m3 /hr. The reaction was terminated when it was confirmed that 90% or more of the theoretical amount of reaction water had distilled into the sample tube, yielding an unsaturated dicarboxylic acid ester compound (D1). The mass ratio of the monoester compound to the diester compound in the resulting unsaturated dicarboxylic acid ester compound (D1) was 16:84.

[Production Example 3: Preparation of unsaturated dicarboxylic acid ester compounds (D2) to (D11)]
As shown in Table 1, unsaturated dicarboxylic acid ester compounds (D2) to (D11) were produced in the same manner as in Production Examples 1 and 2, except that the number of moles of alkylene oxide added (4 moles to 23 moles), the type of alkylene oxide (EO: ethylene oxide, PO: propylene oxide), and the acid (see a. Acid group in Table 1: fumaric acid, maleic anhydride, maleic acid) in the methanol alkylene oxide adduct (see b. Glycol type in Table 1) were varied. Table 1 also shows the results of quantifying the mass ratio (ester ratio) of the monoester compound to the diester compound in the unsaturated dicarboxylic acid ester compounds (D2) to (D11) according to the HPLC measurement conditions shown in <Method for quantifying the ratio of monoester to diester> described below.
The HPLC chart of the unsaturated dicarboxylic acid ester compound (D6) is shown in Figure 1. In Figure 1, the peak at about 2.3 minutes corresponds to the peak derived from the monoester compound, and the peak at about 3.3 minutes corresponds to the peak derived from the diester compound.

<Method for quantifying the ratio of monoesters to diesters>
<HPLC measurement conditions>
Measurement device: Shimadzu Corporation Liquid chromatography column: CAPCELL PAK C18 (Osaka Soda Co., Ltd.)
Flow rate: 1.0 ml/min, temperature: 40°C, sample concentration: 1 wt%/eluent, injection volume: 20 μl
Eluent: a mixture of water and acetonitrile (volume ratio: water/acetonitrile = 57/43)
Detector: differential refractometer, calibration curve: polyethylene glycol

[Production Example B1 (Production of Polycarboxylic Acid Polymer)]
A stainless steel autoclave equipped with a nitrogen inlet tube, a stirrer, and a thermometer was charged with 150 g of 3-methyl-3-buten-1-ol 11EO adduct (MBO11EO), 340 g of ion-exchanged water, 57 g of fumaric acid, and 349 g of unsaturated dicarboxylic acid ester compound (D1) while stirring. After thorough nitrogen replacement and heating to 60°C, 2.3 g of a 35% aqueous solution of hydrogen peroxide and 0.01 g of iron (II) sulfate heptahydrate were charged. Next, 8.6 g of a 10% aqueous solution of L-ascorbic acid was added dropwise over 120 minutes while stirring at 60°C for 4 hours, completing the polymerization reaction. After completion of the reaction, the temperature was raised to 95°C and stirring was continued for 1 hour. The polymerization solution was cooled to 50° C. and neutralized with 61 g of a 48% aqueous solution of sodium hydroxide to obtain 968 g of an aqueous solution of polycarboxylic acid polymer B1 (solid concentration: 60.1%, weight average molecular weight: 14,000).

[Production Examples B2 to B8: Production of Polycarboxylic Acid Polymers]
As shown in Table 2, polycarboxylic acid polymers (B2) to (B8) of the present invention were produced in the same manner as in Production Example B1, except that the types of reactive alcohol derivative, unsaturated carboxylic acid compound, and unsaturated dicarboxylic acid ester compound were changed.

[Production Example A1 (Production of EO-added polyamidepolyamine)]
A reactor equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a condenser-equipped dipstick tube was charged with 199 g of polyalkylene polyamine (manufactured by Tosoh Corporation, product name: Polyeite) and 68 g of adipic acid. The mixture was stirred while introducing nitrogen, and then heated to 160°C. The reaction was continued for 8 hours and terminated when the acid value reached 10. The amount of water removed by the reaction was 17 g. 339 g of water was then added to form an aqueous solution, which was then cooled to 60°C. 89 g of ethylene oxide was added at the same temperature over 4 hours, and the mixture was then aged for 1 hour to obtain 678 g of an aqueous solution of EO-added polyamide polyamine A1 (solids concentration: 50%).

[Production Example B9: Production of polycarboxylic acid polymer]
A stainless steel autoclave equipped with a nitrogen inlet tube, stirrer, and thermometer was charged with 222 g of 3-methyl-3-buten-1-ol 40EO adduct (MBO40EO), 242 g of ion-exchanged water, 28.3 g of fumaric acid, 3.7 g of acrylic acid, and 126.3 g of an unsaturated dicarboxylic acid ester compound (Compound D3) while stirring. After thorough nitrogen replacement and heating to 60°C, 17.1 g of a 14% aqueous solution of sodium persulfate was added and the reaction was allowed to proceed for 6 hours while maintaining the same temperature. After completion of the reaction, the temperature was raised to 80°C and stirring was continued for 1 hour. Next, 40.8 g of an aqueous solution of polyamidepolyamine A1 and 331 g of ion-exchanged water were added, followed by stirring for an additional 1 hour. The polymerization solution was cooled to 50°C and neutralized with 17.3 g of a 48% aqueous solution of sodium hydroxide to obtain 994 g of an aqueous solution of polycarboxylic acid polymer B9 (solids concentration: 41.0%, weight average molecular weight: 15,000).

[Production Example C1 (Production of Comparative Polycarboxylic Acid Polymer)]
A stainless steel autoclave equipped with a nitrogen inlet tube, a stirrer, and a thermometer was charged with 374 g of 3-methyl-3-buten-1-ol 50EO2PO adduct (block adduct, MBO50EO2PO), 260 g of ion-exchanged water, 12.3 g of fumaric acid, 5.2 g of maleic anhydride, and 91 g of an unsaturated dicarboxylic acid ester compound (Compound D7) while stirring. After thorough nitrogen replacement and heating to 60°C, 22.5 g of a 14% aqueous solution of sodium persulfate was charged and the reaction was allowed to proceed for 6 hours while maintaining the same temperature. After completion of the reaction, the temperature was raised to 80°C and stirring was continued for 1 hour. Next, 27.1 g of an aqueous solution of polyamidepolyamine A1 and 201 g of ion-exchanged water were added, and the mixture was further stirred for 1 hour. The polymerization solution was cooled to 50° C. and neutralized with 6.5 g of a 48% aqueous solution of sodium hydroxide to obtain 1,000 g of an aqueous solution of polycarboxylic acid polymer C1 (solid concentration: 50.1%, weight average molecular weight: 24,000).

As shown in Table 3, polycarboxylic acid polymers (C2) to (C3) were produced using the same procedure as in Production Example C1, except that the types of reactive alcohol derivative, unsaturated carboxylic acid compound, and unsaturated dicarboxylic acid ester compound were changed.

Furthermore, as shown in Table 3, polycarboxylic acid polymers (C4) to (C5) were produced using the same procedure as in Production Example B1, except that the types of reactive alcohol derivative, unsaturated carboxylic acid compound, and unsaturated dicarboxylic acid ester compound were changed.

[Examples 1 to 9 and Comparative Examples 1 to 5: Fresh Concrete Test]
Using the polycarboxylic acid polymers B1 to B9 and polycarboxylic acid polymers C1 to C5 obtained in the above Production Examples, fresh concrete tests were carried out with the concrete compositions shown in Table 4 (ordinary Portland cement, W/C = 60%, test temperature: 20°C), Table 7 (ordinary Portland cement, W/C = 30%, test temperature: 20°C), Table 10 (moderate heat Portland cement, W/C = 30%, test temperature: 20°C), and Table 13 (moderate heat Portland cement, W/C = 30%, test temperature: 10°C).

The concrete was mixed using a 55-liter forced biaxial mixer. Water prepared by adding each polycarboxylic acid polymer (B1 to B9, C1 to C5) to the coarse aggregate, cement, and fine aggregate was added and mixed for 90 seconds. After leaving the concrete to stand for 5 minutes, fresh concrete tests (slump test JIS A 1101 (measurement of the spread of fresh concrete as a flow value), air content (JIS A 1128), and setting test (time until penetration resistance reaches 3.5 N/ ^mm2 , corresponding to the initial setting time)) were conducted immediately after the concrete was discharged. Furthermore, the compressive strength of each 28-day-old specimen was measured according to the procedure of JIS A 1108, and the average compressive strength (N/ ^mm2 ) of three specimens for each Example or Comparative Example at 28 days was recorded.

[Fresh concrete test results (1)]
Table 4 shows the concrete mix, and Tables 5 and 6 show the fresh concrete test results.

[Fresh concrete test results (2)]
Table 7 shows the concrete mix, and Tables 8 and 9 show the fresh concrete test results.

[Fresh concrete test results (3)]
Table 10 shows the concrete mix, and Tables 11 and 12 show the fresh concrete test results.

[Fresh concrete test results (4)]
Table 13 shows the concrete mix, and Tables 14 and 15 show the fresh concrete test results.

As shown in Tables 5, 8, 11, and 14 above, Examples 1 to 9, 10 to 18, 19 to 27, and 28 to 36, which used Polymers B1 to B9, did not cause material separation even when the cement type, concrete mix, or temperature environment was changed, and the results showed that they had appropriate dispersibility, air content, setting time, and compressive strength according to the mix.
On the other hand, as shown in Tables 6, 9, 12, and 15, in Comparative Examples 1 to 5, 6 to 10, 11 to 15, and 16 to 20, which used Polymers C1 to C5, the test results varied when the cement type, concrete mix, and temperature environment changed, and the performance as a dispersant could not be maintained. Dispersibility became too high after 30 minutes in Comparative Examples 1 to 5, and after 60 minutes in Comparative Examples 6 to 10, 11 to 15, and 16 to 20, resulting in material separation.
Furthermore, as shown by the flow value results for Comparative Examples 6 to 10, 11 to 15, and 16 to 20, in these Comparative Examples, fluidity increased dramatically between 0 and 30 minutes, making quality control difficult. When considering application to ordinary ready-mixed concrete (concrete that is mixed at a factory, then transported to the pouring site and poured), the extreme increase in fluidity at the initial stage of mixing is likely to lead to an increase in the amount of chemicals used at the construction site. Furthermore, as shown above, separation over time (too high fluidity) can lead to delayed setting, making it difficult to achieve adequate strength. This can lead to other disadvantages.
On the other hand, in Examples 1 to 36 in which polymers B1 to B9 were used as described above, regardless of the type of cement or the concrete composition or temperature environment, the fluidity (flow value) gradually changed (decreased) over time from 0 minutes to 30 minutes and 60 minutes after mixing, and the fluidity was maintained. Therefore, it can be expected that these polymers will be useful as cement dispersants in which the change in fluidity over time in the early stage of mixing is improved (suppressed) compared to conventional ones.

As described above, the cement dispersant of the present invention, which contains a polycarboxylic acid polymer composed of a reactive alcohol derivative having a polymerizable bond site, an unsaturated dicarboxylic acid as the unsaturated carboxylic acid compound, and an ester having a monoester:diester mass ratio of 10:90 to 25:75 as the unsaturated dicarboxylic acid ester, can stably exhibit its performance when applied to concrete even when the cement type, concrete mix, or temperature environment changes, and therefore can be widely used in a variety of formulations, and further, it has been shown to improve performance that is important when constructing concrete, such as excellent strength development.

Claims (6)

A cement dispersant comprising a polycarboxylic acid polymer comprising a structural unit derived from a polyalkylene glycol alkenyl ether compound, a structural unit derived from an unsaturated carboxylic acid compound, and a structural unit derived from an unsaturated dicarboxylic acid ester compound,
the content ratio of the structural units derived from the unsaturated dicarboxylic acid is 50 to 100% by mass relative to the total mass of the structural units derived from the unsaturated carboxylic acid compound, and
the structural units derived from the unsaturated dicarboxylic acid ester compound are characterized in that a ratio of structural units derived from the unsaturated dicarboxylic acid monoester compound to structural units derived from the unsaturated dicarboxylic acid diester compound is 10:90 to 25:75 in mass ratio;
Cement dispersant. the structural units derived from the unsaturated carboxylic acid compound and the structural units derived from the unsaturated dicarboxylic acid ester compound are in a mass ratio of 1 to 50 mass%:99 to 50 mass%.
The cement dispersant of claim 1. The polycarboxylic acid polymer contains the following structural units (I), (II), (IIIa), and (IIIb),
The content of the structural unit (IIa) derived from the following unsaturated dicarboxylic acid is 50 to 100% by mass relative to the total mass of the following structural unit (II), and
The ratio of the structural unit (IIIa) to the structural unit (IIIb) is 10:90 to 25:75 by mass.
The cement dispersant according to claim 1.
(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, X represents —(CH ₂ )bO—, AO represents an alkylene oxide group having 2 to 4 carbon atoms, a represents the average number of moles of alkylene oxide added and is a number from 1 to 200, and b represents an integer from 1 to 20.)
(In the formula, ^R5 to ^R8 each independently represent a hydrogen atom, a hydrocarbon group having 1 to 22 carbon atoms, or ^-COOM1 , provided that at least one of ^R5 to ^R8 represents ^-COOM1 , and that parts of two of the groups ^R5 to ^R8 can combine to form an acid anhydride. ^M1 represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an alkanolamine.)
(In the formula, ^R5 and ^R6 each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms, and ^M2 and ^M3 each independently represent a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an alkanolamine.)
(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms; M ⁴ represents a hydrogen atom, an alkali metal, an alkaline earth metal, ammonium, or an alkanolamine; Y represents a hydrocarbon group having 1 to 22 carbon atoms or -(AO)c-R ¹¹ , where AO represents an alkylene oxide group having 2 to 4 carbon atoms, c represents the average number of moles of alkylene oxide added and is a number from 1 to 200; and R ¹¹ represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms.)
(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms; Y represents a hydrocarbon group having 1 to 22 carbon atoms or -(AO)c-R ¹¹ , where AO represents an alkylene oxide group having 2 to 4 carbon atoms; c represents the average number of moles of alkylene oxide added and is a number from 1 to 200; and R ¹¹ represents a hydrogen atom or a hydrocarbon group having 1 to 22 carbon atoms.) The structural unit (II), the structural unit (IIIa), and the structural unit (IIIb) are contained in a mass ratio of structural unit (II):[structural unit (IIIa)+structural unit (IIIb)]=1 to 50 mass%:99 to 50 mass%.
The cement dispersant according to claim 3. The cement dispersant according to claim 3 or 4, characterized in that the polycarboxylic acid polymer further contains the following structural unit (IV) in addition to the structural unit (I), the structural unit (II), the structural unit (IIIa), and the structural unit (IIIb):
(In the formula, Z represents a group bonded via an amide bond to a carbon atom in the main chain of a polyamidepolyamine obtained by condensing a dibasic acid with a polyalkylenepolyamine and/or a modified polyamidepolyamine obtained by adding 0.1 to 10 moles of an alkylene oxide having 2 to 4 carbon atoms per equivalent of the active imino group, amino group, or amide residue of the polyamidepolyamine.) A cement dispersant characterized by containing, in addition to the polycarboxylic acid polymer according to any one of claims 1 to 5, a polyamidepolyamine obtained by condensing a dibasic acid with a polyalkylenepolyamine, and/or a modified polyamidepolyamine obtained by adding 0.1 to 10 moles of alkylene oxide having 2 to 4 carbon atoms per equivalent of the active imino group, amino group, or amide residue of the polyamidepolyamine.