JP2008133176A - Cement admixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement admixture which has both of excellent water reducing performance and slump retainability in an area (the weight ratio of water to cement =0.3 to 0.6) where a high performance AE water reducer and an AE reducer are especially used, and which has high economical efficiency because its use amount is small. <P>SOLUTION: The cement admixture contains at least two kinds of copolymers. The cement admixture contains a copolymer (A) and a copolymer (B), each containing a constitutional unit originating in a (poly)alkyleneglycol monoalkenyl ether-based monomer (a) expressed by general formula (1) and a constitutional unit originating in an unsaturated carboxylic acid-based monomer (b). In the formula (1), R<SP>1</SP>O represents one or more kinds of 2-18C oxyalkylene groups; m represents average addition molar number of oxyalkylene groups and is a number of 1-500; R<SP>2</SP>represents a hydrogen atom or a 1-30C hydrocarbon group; and Y represents a 2-8C alkenyl group. The adsorption ratio of the copolymer (A) on cement particles is ≥40% and the adsorption ratio of the copolymer (B) on cement particles is <40%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a cement admixture. More specifically, it is a cement admixture that can be widely used as a water reducing agent for cement compositions such as cement paste, mortar, concrete, and the like. It relates to a cement admixture that can be constructed.

Cement admixture is widely used as a water reducing agent for cement compositions such as cement paste, mortar, and concrete, and is indispensable for building civil engineering and building structures from cement compositions. It has become. Such a cement admixture has the effect of improving the strength, durability, and the like of the cured product by increasing the fluidity of the cement composition and reducing the water content of the cement composition. Among such water reducing agents, those containing a polycarboxylic acid polymer exhibit high water reducing performance as compared with conventional water reducing agents such as naphthalene, and thus have many achievements as high performance AE water reducing agents.

In such a cement admixture, in addition to the water reducing performance for the cement composition, there is a demand for a cement admixture whose viscosity can be improved so that it is easy to work at the site where the cement composition is handled. In other words, the cement admixture used as a water reducing agent will exhibit water reducing performance by lowering the viscosity of the cement composition, but it will exhibit such performance and make it easier to work at the site where it is handled. What can be made to have a high viscosity is required in the production site of civil engineering and building structures. When the cement admixture exhibits such performance, work efficiency and the like in construction of civil engineering and building structures will be improved.

As a method for improving the ability to prevent slump loss of the cement composition, for example, the weight average molecular weight of the polycarboxylic acid polymer is in the range of 10,000 to 500,000 in terms of polyethylene glycol by gel permeation chromatography. And a cement dispersant having a value obtained by subtracting the peak top molecular weight from the weight average molecular weight of 0 to 8,000 is disclosed (for example, see Patent Document 1). It is described that this technique gives excellent fluidity to cement compositions and the like over a long period of time. Further, in this cement dispersant, when the adsorption rate of the polycarboxylic acid polymer to the cement particles is less than 60%, and the adsorption rate of the polycarboxylic acid polymer to the cement particles is 60% or more. Cases are listed. This cement dispersant uses a polycarboxylic acid polymer using (alkoxy) polyalkylene glycol mono (meth) acrylic acid ester monomer, and includes (alkoxy) polyalkylene glycol and (meth) acrylic. Since an esterification step with an acid is included, the manufacturing cost is high, and the cost performance is lowered, so there is room for improvement in this respect. In particular, in a region where a high-performance AE water reducing agent or an AE water reducing agent is used (water / cement weight ratio = 0.3 to 0.6), a material having excellent water reduction performance and slump retention has been demanded. . In addition, there is room for further improvement in water reduction performance and slump retention.
Japanese Patent No. 3179022 (pages 1-2 and 14-15)

The object of the present invention is to improve the above-mentioned problems, and particularly in a region where a high-performance AE water reducing agent or an AE water reducing agent is used (water / cement weight ratio = 0.3 to 0.6) An object of the present invention is to provide a cement admixture that has high retentivity and is low in the amount used and highly economical.

The present inventors can further form a cement composition and the like that are particularly excellent in water reduction and cost performance with respect to the cement admixture required in the construction site of high-strength / ultra-high-strength structures, etc. It was investigated. First, paying attention to the fact that polycarboxylic acid polymers can exhibit excellent water reduction performance with respect to cement compositions, etc., (poly) alkylene glycol monoalkenyl ether copolymers that do not require an esterification step By using the polymer, the cost performance is improved as compared with the (alkoxy) polyalkylene glycol mono (meth) acrylic acid ester system, and the adsorption rate of the copolymer to cement particles is 40% or more, and 40% The present inventors have found that a cement admixture having both excellent water reduction performance and slump retention can be obtained by using less than the polymer in combination, and the present invention has been achieved. In addition, about the measuring method of the adsorption rate to the cement particle of a copolymer, 0.1 weight% of copolymers are converted into solid content with respect to cement as mentioned later, and it measures after 5 minutes at 25 degreeC. Is preferred.
In an ester system obtained by polymerizing a monomer component comprising an (alkoxy) polyalkylene glycol mono (meth) acrylate monomer in a conventional polycarboxylic acid copolymer, the ester system In preparing the monomer, since it is usually industrially difficult to add alkylene oxide to (meth) acrylic acid, after the step of adding alkylene oxide to a compound having an active hydrogen group such as alcohol, (Alkoxy) polyalkylene glycol mono (meth) acrylic acid ester monomer has been prepared through a process for transesterification with (meth) acrylic acid.
On the other hand, the cement admixture of the present invention is an ether-based one containing a copolymer derived from a (poly) alkylene glycol monoalkenyl ether-based monomer. Here, the (poly) alkylene glycol monoalkenyl ether monomer can be prepared by a step of adding an alkylene oxide to a compound having a polymerizable unsaturated bond and an active hydrogen group.
Therefore, the ether-based polymer in the cement admixture of the present invention does not require an esterification step in the monomer preparation step as compared with the ester-based polymer. That is, since it is possible to omit an esterification step with a large load in industrial production, the time required for production can be shortened, and labor can be saved. As a result, the present invention improves the cost performance as described above.
The (poly) alkylene glycol monoalkenyl ether monomer is preferably obtained by a method of preparing an alkylene oxide added to a compound having a polymerizable unsaturated bond and an active hydrogen group, but such a method is not necessarily used. It is not restricted to what is obtained by.

Further, when the ether type and the ester type are compared, the ether type is preferable in that an adsorbent having a wider range of adsorption can be used. For example, ethers are used as cement admixtures under various conditions, such as being able to be applied to various types of cement, due to the wide range of adsorption rates that are effective as cement admixtures. An excellent effect can be exhibited.
Furthermore, in the case of an ester type, if the adsorption rate is high, the fluidity is high immediately after the cement admixture is added to the cement composition or the like and kneaded. Shows a tendency that cement particles aggregate and almost no fluidity is exhibited. On the other hand, in the case of the ether type of the present invention, in the relationship between the adsorption rate and the fluidity, the effect of maintaining the fluidity is high even when the adsorption rate is high. In other words, when the ester type and the ether type are compared, it can be said that the application range of the adsorption rate is different. In addition, the ether type is more effective in specifying the adsorption rate. For example, if the adsorption rate is 40% or more, the ether type exhibits an excellent effect that the effect of maintaining fluidity is higher. In the present invention, water reduction performance and slump retention can be made excellent.
The reason why the ether system has a higher effect of maintaining fluidity than the ester system when the adsorption rate is 40% or more is not clear, but is considered as follows.
That is, since the ester-based copolymer can be copolymerized randomly with an ester-based monomer and a carboxylic acid-based monomer, the distribution of -COOM in the copolymer structure is likely to be distributed. In the copolymer, a copolymer having a very high density of -COOM and a copolymer having a very low density of -COOM are mixed.
On the other hand, in order to increase the adsorption rate, it is only necessary to increase the mass% of the carboxylic acid monomer constituting the copolymer. This is because the density of —COOM, which is an adsorbing group, in the copolymer structure is increased. This is because the speed of adsorption to cement particles is increased.
In order to increase the adsorption rate to 40% or higher, the higher the mass% of the carboxylic acid monomer constituting the ester copolymer, the greater the distribution of -COOM. As a result, many ester-based copolymers having a very high density of -COOM are mixed, and the mixing makes the effect of aggregating stronger than the effect of dispersing the cement particles, and the fluidity is reduced. It is thought that expression becomes impossible.
However, in ether-based copolymers, ether-based monomers are not homopolymerizable, so the polymerization proceeds at approximately the same rate for ether-based monomers and carboxylic acid-based monomers. Even if the mass% of the carboxylic acid monomer constituting the coal is increased, the distribution of -COOM in the copolymer structure hardly occurs.
That is, a copolymer having a very high COOM density that adversely affects the fluidity is less likely to occur in the ether type than in the ester type, and thus the cohesive effect is strong even in the ether type copolymer having a high adsorption rate. It can be used in a wide range with good fluidity.

That is, the present invention is a cement admixture comprising at least two kinds of copolymers,
The cement admixture has the following general formula (1);

(In the formula, R ¹ O represents one or more of oxyalkylene groups having 2 to 18 carbon atoms. M represents the average number of added moles of oxyalkylene groups, and represents the number of 1 to 500. R ² represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and Y represents an alkenyl group having 2 to 8 carbon atoms. It includes a copolymer (A) and a copolymer (B) containing a structural unit derived from an ether monomer (a) and a structural unit derived from an unsaturated carboxylic acid monomer (b), The copolymer (A) is a cement admixture having an adsorption rate to cement particles of 40% or more, and the copolymer (B) is an adsorption rate to cement particles of less than 40%.

In addition, when 3 or more types of copolymers are contained, the combination of any 2 types of copolymers should just satisfy the conditions of the said copolymer (A) and the said copolymer (B). Even in such a case, the copolymer (A) and the copolymer (B) are present in the cement admixture, and the effect of the present invention is exhibited by the two types of copolymers having different adsorption rates. Will be. In this case, it is preferable that the copolymer (A) and the copolymer (B) are main components in the entire copolymer that exhibits cement water reducing performance in the cement admixture. It is preferable that substantially all of the copolymer is constituted by the copolymer (A) and the copolymer (B). For example, as long as the effects of the present invention are exhibited, for example, all copolymers In 100% by mass, the total amount of the copolymer (A) and the copolymer (B) is preferably 50% by mass or more. More preferably, it is 80 mass% or more, More preferably, it is 90 mass% or more.
The present invention is described in detail below.

The copolymer (A) and the copolymer (B) are both (poly) alkylene glycol monoalkenyl ether monomers (a) (hereinafter sometimes simply referred to as monomers (a)). A structural unit derived from an unsaturated carboxylic acid monomer (b) (hereinafter sometimes simply referred to as monomer (b)). That is, the copolymer (A) and the copolymer (B) are both a structural unit derived from the (poly) alkylene glycol monoalkenyl ether monomer (a) and an unsaturated carboxylic acid monomer. And (b) derived structural units.
The copolymer (A) and the copolymer (B) have a structure other than the structural unit derived from the monomer (a) and the structural unit derived from the monomer (b). However, the structural unit derived from the monomer (a) and the structural unit derived from the monomer (b) are preferably main components. The main component means that in 100% by mass of the copolymer, the structural unit derived from the monomer (a) and the structural unit derived from the monomer (b) are 50 to 100% by mass. To do. More preferably, it is 70 mass% or more, More preferably, it is 80 mass% or more, Most preferably, it is 90 mass% or more.

Examples of the alkenyl group having 2 to 8 carbon atoms represented by Y include a vinyl group, an allyl group, a 3-methyl-3-butenyl group, a 2-methyl-3-butenyl group, and 3-methyl-2- Examples include butenyl, 2-methyl-2-butenyl group, 2-butenyl group, 2-methyl-2-propenyl group, 1,1-dimethyl-2-propenyl group and the like.
A preferred form of Y is an alkenyl group having 2 to 8 carbon atoms. More preferably, it is an alkenyl group having 4 to 5 carbon atoms.
R ¹ O represents one or two or more oxyalkylene groups having 2 to 18 carbon atoms. When two or more oxyalkylene groups are present, random addition, block addition, Any addition form such as alternate addition may be used.
The structure composed of the oxyalkylene group represented by R ¹ O is formed of one or more alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, isobutylene oxide, 1-butene oxide, and 2-butene oxide. It is a structure. Among such alkylene oxide adducts, ethylene oxide and propylene oxide are preferable. Further, those mainly composed of ethylene oxide are preferred.

The structure composed of the oxyalkylene group represented by R ¹ O is preferably formed mainly with ethylene oxide. What is mainly formed of ethylene oxide means that when the structure composed of the oxyalkylene group represented by R ¹ O is formed of two or more alkylene oxides, the ethylene oxide is in the number of moles of all alkylene oxides. It means that it occupies the majority. In the present invention, the alkylene oxide that forms the structure composed of the oxyalkylene group represented by R ¹ O is mostly ethylene oxide, so that the copolymer (A) and the copolymer ( The hydrophilicity of B) can be improved moderately, and the effect of water reduction can be sufficiently exhibited by adsorption to cement particles. In the structure composed of the oxyalkylene group represented by R ¹ O, when it is expressed as mol% of oxyethylene groups in 100 mol% of all oxyalkylene groups, it is preferably 50 to 100 mol%. . If it is less than 50 mol%, the hydrophilicity of the structure composed of the oxyalkylene group represented by R ¹ O may be lowered. More preferably, it is 60 mol% or more, more preferably 70 mol% or more, particularly preferably 80 mol% or more, and most preferably 90 mol% or more.

R ² is preferably a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. More preferably a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, still more preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms, particularly preferably a hydrogen atom. It is. When the number of carbon atoms of R ² is greater than 5, the hydrophilicity sufficient to disperse cement particles and the like cannot be imparted, and accordingly, the amount of use is extremely low without obtaining good water reduction performance. May increase. Further, since the surface activity increases, the air entrainment property is improved, and a cement composition containing coarse bubbles is mixed, and the compression hardness of the hardened concrete may not be sufficiently exhibited.
The m is preferably 2 to 400. More preferably, it is 3-300, More preferably, it is 5-250, Most preferably, it is 10-200.
Moreover, it is suitable from a polymeric and hydrophilic surface that it is 10-150. More preferably, it is 20-130, More preferably, it is 25-120.

The unsaturated carboxylic acid monomer (b) may be any monomer having a polymerizable unsaturated group and a group capable of forming a carbanion. Unsaturated dicarboxylic acid monomers and the like are preferred. The unsaturated monocarboxylic acid-based monomer may be any monomer having one unsaturated group and one group capable of forming a carbanion in the molecule. Preferred forms include the following general formula ( It is a compound represented by 2).

In the general formula (2), R ³ and R ⁴ may be the same or different and each represents a hydrogen atom or a methyl group. M represents a hydrogen atom, a metal atom, an ammonium group or an organic amine group.
As the metal atom in M of the general formula (2), a monovalent metal atom such as an alkali metal atom such as lithium, sodium or potassium; a divalent metal atom such as an alkaline earth metal atom such as calcium or magnesium; Trivalent metal atoms such as aluminum and iron are preferred. Moreover, as an organic amine group, alkanolamine groups, such as an ethanolamine group, a diethanolamine group, and a triethanolamine group, and a triethylamine group are suitable. Further, it may be an ammonium group. As such an unsaturated monocarboxylic acid monomer, acrylic acid, methacrylic acid, crotonic acid and the like; monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts thereof are suitable. Among these, methacrylic acid; its monovalent metal salt, divalent metal salt, ammonium salt, and organic amine salt are preferably used from the viewpoint of improving the water reduction performance of the cement, and the unsaturated carboxylic acid monomer (b) It is suitable as.
The unsaturated dicarboxylic acid monomer may be any monomer having one unsaturated group and two groups capable of forming a carbanion in the molecule, but maleic acid, itaconic acid, citraconic acid , Fumaric acid and the like, monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts thereof, or anhydrides thereof are suitable. In addition to these, the unsaturated carboxylic acid monomer (b) is a half ester of an unsaturated dicarboxylic acid monomer and an alcohol having 1 to 22 carbon atoms, an unsaturated dicarboxylic acid and a carbon number. Preference is given to half amides with 1 to 22 amines, half esters of unsaturated dicarboxylic acid monomers and glycols having 2 to 4 carbon atoms, and half amides of maleamic acid and glycols having 2 to 4 carbon atoms.

As the amount of the unsaturated carboxylic acid monomer (b) used increases, the number of carboxyl groups in the copolymer (A) or (B) increases and the adsorption rate increases. In addition, as the average number of added moles of the oxyalkylene group of the (poly) alkylene glycol monoalkenyl ether monomer (a) increases, the number of structures due to the oxyalkylene group of the copolymer increases, and the adsorption rate increases. Get higher.
Preparation of the copolymer (A), that is, a copolymer having an adsorption rate to Portland cement particles of 40% or more includes the use amount of the unsaturated carboxylic acid monomer (b), and the above It is preferable to carry out by appropriately adjusting the average number of added moles of alkylene oxide groups of the (poly) alkylene glycol monoalkenyl ether monomer (a).
The copolymer having an adsorption rate of 40% or more, that is, the copolymer (A) may be prepared in the following forms (1) to (4), for example.
(1) Using the monomer (a) having an average addition mole number of the oxyalkylene group of less than 10 moles, and using the unsaturated carboxylic acid monomer (b) in an amount of 20% by mass or more And
(2) Using the monomer (a) having an average addition mole number of oxyalkylene groups of 10 to 25 mol, and using the unsaturated carboxylic acid monomer (b) in an amount of 15% by mass or more And
(3) The monomer (a) having an average addition mole number of oxyalkylene groups of 25 to 50 mol is used, and the amount of the unsaturated carboxylic acid monomer (b) used is 7% by mass or more. .
(4) Using the monomer (a) having an average addition mole number of oxyalkylene groups of 50 mol or more, and using the unsaturated carboxylic acid monomer (b) in an amount of 5% by mass or more. To do.
The above embodiments (1) to (4) are examples of methods by which the copolymer (A) can be suitably prepared, and the copolymer (A) is not limited to these forms. Absent. These forms are conditions in the vicinity of a critical point that is normally necessary to increase the adsorption rate to 40% or more. When the adsorption rate can be 40% or more due to other factors, the above form (1) It may be outside the range of (4). In the above embodiments (1) to (4), the monomer (a) having a larger average addition mole number of oxyalkylene groups is used, and / or the unsaturated carboxylic acid monomer (b) It is preferable to further improve the adsorption rate by preparing a larger amount of). In addition to these, a copolymer having an adsorption rate of 40% or more can be prepared by referring to the constitution and adsorption rate of the copolymer in Reference Examples of the present specification.

The copolymer (B) may have a structural unit derived from the monomer (c) other than the monomer (a) and the monomer (b). The monomer (c) is preferably a (meth) acrylic acid ester monomer. More preferably, it is a (meth) acrylic acid ester having a hydroxyalkyl group. The (meth) acrylic acid ester having a hydroxyalkyl group is a compound represented by the following general formula (3).

In the general formula (3), R ⁵ and R ⁶ may be the same or different and each represents a hydrogen atom or a methyl group. R ⁷ represents a hydroxyalkyl group having 1 to 10 carbon atoms.
When R ⁷ is a hydroxyalkyl group, sufficient hydrophilicity can be imparted to disperse cement particles and the like.
R ⁷ is more preferably a hydroxyalkyl group having 1 to 5 carbon atoms, still more preferably a hydroxyalkyl group having 1 to 3 carbon atoms, and particularly preferably a hydroxyalkyl group having 2 carbon atoms. It is. Most preferred as the compound represented by the general formula (3) is 2-hydroxyethyl acrylate.
If the number of carbon atoms of R ⁷ is too large, sufficient hydrophilicity cannot be imparted to disperse cement particles and the like, and accordingly, a good water reduction performance cannot be obtained and the amount used is extremely increased. There is a fear. Further, since the surface activity increases, the air entrainment property is improved, and a cement composition containing coarse bubbles is mixed, and the compression hardness of the hardened concrete may not be sufficiently exhibited.
The R ⁵ and R ⁶ are preferably hydrogen atoms.

When the copolymer (B) has a structural unit derived from the monomer (c), the structural unit derived from the monomer (c) is 30% by mass or less in 100% by mass of the copolymer. It is preferable. More preferably, it is 20 mass% or less, More preferably, it is 10 mass% or less.
Such a range is advantageous because the copolymer (B) excellent in slump retention can be effectively prepared.

What is necessary is just to prepare the copolymer whose said adsorption rate is less than 40%, ie, the said copolymer (B), with a form like following (5)-(8), for example.
(5) The monomer (a) having an average addition mole number of the oxyalkylene group of less than 10 moles and the amount of the unsaturated carboxylic acid monomer (b) used is less than 20% by weight. And
(6) Using the monomer (a) having an average addition mole number of oxyalkylene group of 10 to 25 mol, and using the unsaturated carboxylic acid monomer (b) in an amount of less than 15% by mass And
(7) Using the monomer (a) having an average addition mole number of oxyalkylene group of 25 to 50 mol, and using the unsaturated carboxylic acid monomer (b) in an amount of less than 7% by mass And
(8) Using the monomer (a) having an average addition mole number of oxyalkylene groups of 50 mol or more, and the amount of the unsaturated carboxylic acid monomer (b) used is less than 5% by mass. To do.
The above embodiments (5) to (8) are examples of methods for suitably preparing the above copolymer (B), and the copolymer (B) is not limited to these forms. Absent. These forms are conditions in the vicinity of a critical point that is usually necessary to make the adsorption rate less than 40%. When the adsorption rate can be made less than 40% due to other factors, the above form (5) It may be outside the range of (8). In the above embodiments (5) to (8), the monomer (a) having a smaller average added mole number of oxyalkylene groups is used, and / or the unsaturated carboxylic acid monomer (b) It is preferable to further reduce the adsorption rate by preparing a smaller amount of). In addition to these, it is possible to prepare a copolymer having an adsorption rate of less than 40% by referring to the constitution and adsorption rate of the copolymer in Reference Examples of the present specification.

In the cement admixture of the present invention, a copolymer (A) having an adsorption rate to cement particles of 40% or more and a copolymer (B) having an adsorption rate to cement particles of less than 40% are used. However, when the adsorption rate is measured and evaluated, when it is added so that the solid content of the copolymer is 0.1% by mass with respect to 100% by mass of cement, 25 ° C. after 5 minutes from the addition. It is preferable to evaluate the adsorption rate of the copolymer by measuring the adsorption rate to the cement particles.
In this case, when the copolymer (A) is added so that the solid content of the copolymer is 0.1% by mass with respect to 100% by mass of the cement, the copolymer (A) is added at 25 ° C. 5 minutes after the addition. When the adsorption rate to the cement particles is 40% or more and the copolymer (B) is added so that the solid content of the copolymer is 0.1% by mass with respect to 100% by mass of the cement, The adsorption rate to cement particles at 25 ° C. after 5 minutes from the addition is less than 40%.

For example, the adsorption rate is preferably measured as follows.
In a room adjusted to 25 ° C., first, a beaker is charged with a polymer or an aqueous solution in which the polymer is dissolved so as to be 0.1% by mass in terms of solid content with respect to 100% by mass of ordinary Portland cement. To a total of 100 g and stir with a stirrer to dissolve evenly. Next, 100 g (100% by weight in terms of water / cement ratio) of cement is added to the same beaker while stirring with a stirrer, and the mixture is stirred for 5 minutes, and then filtered to collect the filtrate. The amount of the polymer remaining in the obtained filtrate is measured with a differential refractometer (hereinafter also referred to as RI). Then, the adsorption rate is calculated by the following formula.
Adsorption rate (%) = {[(Area area of copolymer on the RI chart of 0.1 mass% aqueous solution) − (Area area of copolymer on the RI chart of cement filtrate after adsorption)] / (Area area of copolymer on RI chart of 0.1 mass% aqueous solution)} × 100
Although the adsorption rate test can be performed at room temperature, it is preferably performed at 25 ° C. as described above. In addition, it is preferable to keep the room temperature at 25 ° C. from the start of the test to the time of measuring the adsorption rate.

As the cement used in the adsorption rate test, it is preferable to use ordinary Portland cement. As the ordinary Portland cement, it is preferable to use one to meet JIS ^{R-5210 -2003,} for example, it is preferable to use the Pacific Ocean Cement Co. ordinary Portland cement. The ordinary Portland cement manufactured by Taiheiyo Cement Co., Ltd. usually has the following characteristics.
Loss on ignition: 1.81 (lg.loss%)
Magnesium oxide content: 1.28 (mass%)
Sulfur trioxide content: 2.09 (mass%)
Chloride ion content: 0.017 (mass%)
Total alkali content: 0.51 (mass%)
Tricalcium silicate content: 54 (mass%)
Dicalcium silicate content: 21 (mass%)
Tricalcium aluminate content: 9 (mass%)
Tetracalcium iron aluminate content: 9 (mass%)
Density: 3.16 (g / cm ³ )
Specific surface area: 3300 (cm ² / g)
Condensation amount of water: 27.6%, start: 2-20 (h-min), end: 3-30 (h-min)
Heat of hydration 7 days: 331 (J / g), 28 days: 379 (J / g)

As the differential refractometer, for example, the following GPC molecular weight measurement conditions are preferably used. GPC refers to gel permeation chromatography (gel permeation chromatography; hereinafter referred to as “GPC”). More specifically, a differential refraction detector (referred to as RI) was used under the following conditions. It is a molecular weight measuring device calculated from a standard substance.
(GPC molecular weight measurement conditions)
Column used: TSK guard Column SWXL + TSKge1 G4000SWXL + G3000SWXL + G2000SWXL manufactured by Tosoh Corporation
Eluent: An eluent solution prepared by dissolving 115.6 g of sodium acetate trihydrate in a mixed solvent of 10999 g of water and 6001 g of acetonitrile and adjusting the pH to 6.0 with acetic acid is used.
Implanted amount: 0.1% aqueous solution or 100 μL of filtrate obtained by measuring adsorption rate
Eluent flow rate: 0.8 mL / min
Column temperature: 40 ° C
Standard substance: polyethylene glycol, peak top molecular weight (Mp) 272500, 219300, 85000, 46000, 24000, 12600, 4250, 7100, 1470
Calibration curve order: Tertiary detector: 410 manufactured by Waters, Japan 410 Differential refraction detector analysis software: MILRENNIUM Ver. Manufactured by Waters, Japan 3.21
The area of the copolymer content on the RI chart is the molecular weight distribution chart in which the 0.1 wt% aqueous solution or the cement filtrate after adsorption is measured using GPC, the vertical axis is the elution capacity, the horizontal If the axis is the elution time (the higher the molecular weight, the faster the elution). Of the part surrounded by the curve showing the molecular weight distribution and the straight line showing the baseline, the peak of the copolymer component is detected. It means area. In the molecular weight measurement by GPC, the higher the molecular weight, the faster the elution. Therefore, following the peak formed by the copolymer, for example, the oligomer by-produced in the preparation of the copolymer and the remaining monomer However, the area formed by these low molecular weight substances is not included in the area of the copolymer. In the curve showing the molecular weight distribution, a line perpendicular to the baseline is drawn from the first valley after the copolymer is eluted (hereinafter simply referred to as a perpendicular), and the curve and the baseline showing the perpendicular and the molecular weight distribution are drawn. It is preferable that the area surrounded by is the area of the copolymer on the RI chart. The method for measuring the area of the copolymer is not particularly limited as long as it is a method capable of measuring the area surrounded by the perpendicular line, the curve indicating the molecular weight distribution, and the base line. For example, MILLENNIUM Ver manufactured by Waters, Japan . It is preferred to measure by 3.21. The method for measuring the adsorption rate will be specifically described with reference to the drawings in Examples described later.
The copolymer adsorbed on the cement particles is filtered out and removed from the solution, so that it is not detected in the molecular weight measurement. Therefore, this area is a value proportional to the total weight of the copolymer contained in the liquid. Therefore, if this area is used to calculate the above equation, the adsorption rate of the polymer, that is, the copolymer 100 It is possible to calculate how many weight% of the copolymer is adsorbed on the cement particles in the weight%. For example, if all the polymer is adsorbed on cement particles and not detected from the filtrate, the adsorption rate is 100%. Thus, the said adsorption rate is a value showing how many weight% of copolymers adsorb | suck to cement particles in 100 weight% of copolymers. Therefore, as long as such a value can be calculated, the adsorption rate is not limited to the method based on the above-described calculation formula using the area of the copolymer, and can be appropriately calculated by other methods.

In addition, although it is suitable to perform the said measurement using normal Portland cement, it does not mean that the cement admixture of this invention is effective only for normal Portland cement. Even if it is other cement particles, if the cation is present on the surface of the cement particles and is positively charged, it is derived from the structures of the copolymer (A) and the copolymer (B). And it is thought that a difference arises in an adsorption rate, and the effect of the present invention can be exhibited.
If there is a difference in the adsorption rate of the copolymer as described above, the water absorption of cement particles and the like is improved by the copolymer having a high adsorption rate, and the slump retention performance is exhibited by the copolymer having a low adsorption rate. It will be. As a result, these performances are exhibited in a well-balanced manner, and it is possible to obtain a cement admixture that has both excellent water reduction performance and slump retention, and has a small amount of use and high economic efficiency. Conventionally, a copolymer having a relatively high water-reducing property and a copolymer having a relatively high slump retention performance are combined, and such a combination is related to the adsorption rate of the copolymer to cement particles. I don't see any knowledge about this. Therefore, it can be said that there is a feature of the present invention.
In addition, the presence of cations on the surface of the particles and being positively charged is considered to be a common property in cement and the like contained in the cement composition in which the cement admixture is used.
From these facts, it can be said that the same effect can be exerted on other cements and the like by using a copolymer having an adsorption rate as measured above using ordinary Portland cement.
That is, when the cement admixture is added using ordinary Portland cement so that the solid content of the copolymer is 0.1% by mass with respect to 100% by mass of cement, 25 minutes after the addition. It is preferable to use the copolymer (A) and the copolymer (B) whose adsorption rate to the cement particles at the temperature is as described above, and for a cement composition composed of ordinary Portland cement. Although it can be said that it is particularly suitable to apply, cement admixture is not limited to the type of cement, i.e., ordinary Portland cements other than those having the above characteristics, and compositions composed of other cements, etc. Any cement composition (so-called cement composition including mortar, concrete, etc.) to be used can be applied. On the other hand, it can be said that the adsorption rate of the copolymer with respect to the cement or the like contained in the cement composition in which the cement admixture is used is as described above. As described above, if the copolymer adsorption rate measured using ordinary Portland cement is as described above, it can also be used for cement compositions using other cements and the like.

One of the preferred embodiments of the present invention is that the adsorption rate of the copolymer (A) to the cement particles is 43% or more.
Specifically, as the above form, when the adsorption rate to the cement particles after 5 minutes from the addition of the copolymer (A) is 43% or more, desired fluidity and slump value can be obtained with a small amount of use. Therefore, the excellent water reduction performance will be exhibited more.
The adsorption rate to the cement particles after 5 minutes from the addition of the copolymer (A) is preferably 43% or more. More preferably, it is 45% or more, still more preferably 55% or more, and particularly preferably 60% or more.

It is also a preferred embodiment of the present invention that the adsorption rate of the copolymer (B) to cement particles is less than 35%.
Specifically, as the above form, when the adsorption rate to the cement particles after 5 minutes from the addition of the copolymer (B) is less than 35%, the rate of adsorption at the initial stage is slow, and the rate of adsorption later Therefore, excellent slump retention is more exhibited.
The adsorption rate to the cement particles after 5 minutes from the addition of the copolymer (B) is preferably less than 35%. Particularly preferably, it is less than 25%.

One of the preferred embodiments of the present invention is that the difference between the adsorption rate of the copolymer (A) to the cement particles and the adsorption rate of the copolymer (B) to the cement particles is 5% or more. It is.
Specifically, the adsorption rate to the cement particles 5 minutes after the addition of the copolymer (A) and the adsorption rate to the cement particles 5 minutes after the addition of the copolymer (B) as the above form If the difference is 5% or more, the effect of combining excellent water reduction performance and slump retention will be more exhibited.
The cement admixture having the above-described form can be obtained, for example, by preparing the copolymer (A) and the copolymer (B) and then appropriately mixing them.
The difference in the adsorption rate is preferably 10% or more. More preferably, it is 15% or more, still more preferably 20% or more, particularly preferably 25% or more, and most preferably 30% or more. More preferably, it is 40% or more.
The difference in the adsorption rate is a value obtained by subtracting the adsorption rate of the copolymer (B) from the adsorption rate of the copolymer (A). For example, when the adsorption rate of the copolymer (A) is 60% and the adsorption rate of the copolymer (B) is 30%, the difference in the adsorption rate is 60% -30% = 30%.

When the cement admixture is blended so that the average adsorption rate is 50% or more, a cement admixture with particularly excellent dispersibility can be obtained, and when blended so that the average adsorption rate is 40% or less, the retainability is particularly high. When an excellent cement admixture is obtained and blended so as to have an average adsorption rate of 40 to 50%, a cement admixture with an excellent balance between dispersibility and retention can be obtained. Therefore, it is preferable to adjust the blending ratio of the polymer according to the required performance.

It is one of the preferred embodiments of the present invention that the cement admixture has a mass ratio of the copolymer (A) to the copolymer (B) of 1: 9 to 9: 1.
When the mass ratio is 1: 9 to 9: 1, the effect of combining excellent water reduction performance and slump retention will be more exhibited.
The cement admixture in which the mass ratio of the copolymer (A) to the copolymer (B) is 1: 9 to 9: 1 includes, for example, the copolymer (A) and the copolymer (B), respectively. After the preparation, it can be obtained by appropriately mixing each appropriate amount. In addition, the said mass ratio is a value by solid content conversion.
The mass ratio is preferably 1: 5 to 5: 1. More preferably, it is 1: 4-4: 1. More preferably, it is 1: 3 to 3: 1. Most preferably, it is 1: 2.5-2.5: 1. Most preferably, it is 1: 2 to 2: 1.

The weight average molecular weight of the copolymer (A) has less influence on the adsorption rate than the acid amount, and the tendency that the influence of the weight average molecular weight on the adsorption rate decreases as the acid amount decreases.
The weight average molecular weight of the copolymer (A) is the structure derived from the (poly) alkylene glycol monoalkenyl ether monomer (a) constituting the copolymer (A), particularly the average addition of alkylene oxide groups. Although it cannot be uniquely determined due to differences in the number of moles and the amount of acid,
The copolymer (A) preferably has a weight average molecular weight of 20000 or more. More preferably, it is 30000 or more, More preferably, it is 40000 or more.
The copolymer (B) preferably has a weight average molecular weight of 50000 or less. More preferably, it is 40000 or less, More preferably, it is 30000 or less, Most preferably, it is 20000 or less.
In addition, the weight average molecular weight of a polymer is a weight average molecular weight of polyethylene glycol conversion by GPC, and it is preferable to measure on the following GPC measurement conditions.
(GPC molecular weight measurement conditions)
Column used: TSK guard Column SWXL + TSKge1 G4000SWXL + G3000SWXL + G2000SWXL manufactured by Tosoh Corporation
Eluent: An eluent solution prepared by dissolving 115.6 g of sodium acetate trihydrate in a mixed solvent of 10999 g of water and 6001 g of acetonitrile and adjusting the pH to 6.0 with acetic acid is used.
Implanted amount: 100 μL of 0.5% eluent solution
Eluent flow rate: 0.8 mL / min
Column temperature: 40 ° C
Standard substance: polyethylene glycol, peak top molecular weight (Mp) 272500, 219300, 85000, 46000, 24000, 12600, 4250, 7100, 1470
Calibration curve order: Tertiary detector: 410 manufactured by Waters, Japan 410 Differential refraction detector analysis software: MILRENNIUM Ver. Manufactured by Waters, Japan 3.21

The inventors of the present invention adsorbed the copolymer (A) and the copolymer (B) to the cement particles more rapidly as the molecular weight becomes higher. In particular, it was discovered that low molecular weight substances were adsorbed sequentially. Furthermore, the present inventors have started such adsorption immediately after the cement particles have come into contact with the cement admixture. In the case of the copolymer (A), the adsorption can be performed for about 1 hour or more. In the case of the copolymer (B), saturation adsorption is reached in about 2 hours or more.

And the said copolymer (B) suppresses initial adsorption | suction to a cement particle as much as possible, and earns subsequent adsorption | suction over time, and improves or maintains a cement water reduction performance with time. On the contrary, the copolymer (A) ends the adsorption to the cement particles in a very short time, and improves the initial cement water reduction performance.

The copolymer (A) and the copolymer (B) preferably have separate peaks on the GPC chart. Each having a separate peak means that the copolymer (A) has one peak or peak and the copolymer (B) has one peak or peak, and each peak overlaps. Also good.
If it is a copolymer which has a respectively separate peak or peak, it can be said that the effect by the difference in adsorption rate is fully exhibited. The reason why the peaks may overlap is that the adsorption rate is not determined only by the molecular weight, but is also affected by the average number of moles added of the oxyalkylene group and the content of the unsaturated carboxylic acid monomer (b). This is because that.

As a method for preparing the copolymer (A) and the copolymer (B), for example, a monomer component and a polymerization initiator are used and a normal polymerization method such as solution polymerization or bulk polymerization is performed. be able to. As the polymerization initiator, those usually used can be used. Persulfates such as ammonium persulfate, sodium persulfate and potassium persulfate; hydrogen peroxide; azobis-2-methylpropionamidine hydrochloride, azoisobutyro Preferred are azo compounds such as nitriles; peroxides such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide. In addition, as a promoter, reducing agents such as sodium bisulfite, sodium sulfite, Mole salt, sodium pyrobisulfite, formaldehyde sodium sulfoxylate, ascorbic acid; and amine compounds such as ethylenediamine, sodium ethylenediaminetetraacetate, glycine, etc. You can also. These polymerization initiators and accelerators may be used alone or in combination of two or more.
The water-soluble polymerization uses, as a polymerization initiator, a water-soluble polymerization initiator such as ammonia or alkali metal persulfate: hydrogen peroxide; azoamidine compounds such as azobis-2methylpropionamidine hydrochloride, Accelerators such as sodium bisulfite can also be used in combination. When a lower alcohol, aromatic or aliphatic hydrocarbon, ester compound or ketone compound is used as a polymerization solvent, a peroxide such as benzoyl peroxide or lauroyl peroxide; a hydroperoxide such as cumene hydroperoxide; An azo compound such as azobisisobutyronitrile is used as a polymerization initiator. In this case, an accelerator such as an amine compound can be used in combination. Furthermore, when a water-lower alcohol mixed solvent is used, it can be appropriately selected from the above-mentioned various polymerization initiators or combinations of polymerization initiators and accelerators.
The bulk polymerization uses a peroxide such as benzoyl peroxide or lauroyl peroxide as a polymerization initiator, a hydroperoxide such as cumene hydroperoxide, an azo compound such as azobisisobutyronitrile, and the like at a temperature of 50 to 200 ° C. It is preferable to carry out within the range.

In the said copolymerization method, it is preferable to copolymerize a monomer component by making the neutralization rate of the said unsaturated monocarboxylic-acid type monomer (b) 0-60 mol%. The neutralization rate of the unsaturated monocarboxylic acid monomer (b) is the amount of unsaturation forming a salt when the total number of moles of the unsaturated monocarboxylic acid monomer (b) is 100 mol%. It is represented by mol% of the monocarboxylic acid monomer (b). When the neutralization rate of the unsaturated monocarboxylic acid monomer (b) exceeds 60 mol%, the polymerization rate in the copolymerization process does not increase, the molecular weight of the resulting polymer decreases, or the production efficiency decreases. There is a risk. More preferably, it is 50 mol% or less, More preferably, it is 40 mol% or less, More preferably, it is 30 mol% or less, Especially preferably, it is 20 mol% or less, Most preferably, it is 10 mol% or less.
As a method for carrying out the copolymerization with the neutralization rate of the unsaturated monocarboxylic acid monomer (b) being 0 to 60 mol%, the unsaturated monocarboxylic acid monomer (b), which is all in acid form, A method in which all unsaturated monocarboxylic acid monomers (b) in which M in the general formula (2) is a hydrogen atom are subjected to copolymerization without neutralization; When the acid monomer (b) is neutralized into a salt form such as a sodium salt or an ammonium salt using an alkaline substance, the neutralization rate is set to 0 to 60 mol% by subjecting to copolymerization. The method is preferred.

In the above copolymerization method, a chain transfer agent can be used as necessary, and one or more commonly used ones can be used. As such a chain transfer agent, a hydrophilic chain transfer agent is preferably used, but a hydrophobic chain transfer agent can also be used as necessary. In the copolymerization method, when the monomer component includes one or more of a monomer having an oxyalkylene group, that is, a polyalkylene glycol unsaturated monomer (a), a hydrophobic chain A transfer agent can also be used.
When a chain transfer agent is used in the copolymerization, the molecular weight adjustment of the obtained copolymer (A) and copolymer (B) becomes easy. In particular, it is effective to use a chain transfer agent when the polymerization reaction is performed at a high concentration in which the amount of all monomers used is 30% by weight or more based on the total amount of raw materials used during polymerization. The chain transfer agent is preferably always present in the reaction system during the copolymerization. In particular, when using a thiol chain transfer agent or a lower oxide and a salt thereof as the chain transfer agent, without adding the chain transfer agent all at once, continuously by dropping or the like, It is effective to add them sequentially into the reaction vessel over a long period of time. If the concentration of the chain transfer agent with respect to the monomer is extremely different between the initial and second half of the reaction, and the chain transfer agent is insufficient in the second half of the reaction, the molecular weight of the copolymer becomes extremely large, which makes it a cement admixture. Will drop.

As the hydrophilic chain transfer agent, commonly used ones can be used, such as mercaptoethanol, thioglycerol, thioglycolic acid, mercaptopropionic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, 2 -Thiol chain transfer agents such as mercaptoethanesulfonic acid; primary alcohols such as 2-aminopropan-1-ol; secondary alcohols such as isopropanol; phosphorous acid, hypophosphorous acid and salts thereof (hypophosphorous acid) Sodium, potassium hypophosphite, etc.), sulfurous acid, hydrogen sulfite, dithionite, metabisulfite and its salts (sodium sulfite, sodium bisulfite, sodium dithionite, sodium metabisulfite, potassium sulfite, hydrogen sulfite) Potassium, potassium dithionite, potassium metabisulfite Lower oxides and salts thereof are preferred in).

The hydrophilic chain transfer agent may be used in combination with one or two hydrophobic chain transfer agents as required. The hydrophobic chain transfer agent is preferably a thiol compound having a hydrocarbon group having 3 or more carbon atoms or a compound having a solubility in water of 25 ° C. of 10% or less. The chain transfer agent, butanethiol, octane described above Thiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, cyclohexyl mercaptan, thiophenol, octyl thioglycolate, octyl 2-mercaptopropionate, octyl 3-mercaptopropionate, 2-ethylhexyl ester mercaptopropionate, octanoic acid 2 -Thiol chain transfer agents such as mercaptoethyl ester, 1,8-dimercapto-3,6-dioxaoctane, decanetrithiol, dodecyl mercaptan; carbon tetrachloride, carbon tetrabromide, methylene chloride, bromoform, Halides mode trichloroethane; alpha-methylstyrene dimer, alpha-terpinene, .gamma.-terpinene, dipentene, unsaturated hydrocarbon compounds such as terpinolene are preferable. These may be used alone or in combination of two or more. Among these, it is preferable to include a thiol chain transfer agent having a hydrocarbon group having 3 or more carbon atoms.

As a method for adding the chain transfer agent to the reaction vessel, a batch addition method in which the whole amount is directly added to the reaction vessel, or a continuous addition method such as dropping or divided addition can be applied. A chain transfer agent may be introduced alone into the reaction vessel, and a monomer having an oxyalkylene group constituting the monomer component, that is, a (poly) alkylene glycol monoalkenyl ether monomer (a) Or may be introduced into the reaction vessel after being previously mixed with a solvent or the like.
The copolymerization method can be carried out either batchwise or continuously. Moreover, as a solvent used as needed in the case of copolymerization, what is usually used can be used, water; alcohols, such as methyl alcohol, ethyl alcohol, isopropyl alcohol; benzene, toluene, xylene, cyclohexane, n -Aromatic or aliphatic hydrocarbons such as heptane; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone are preferred. These may be used alone or in combination of two or more. Among these, from the solubility point of the monomer component and the resulting polycarboxylic acid polymer, one or more solvents selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms are used. It is preferable to use it.
In the above copolymerization method, monomer components, polymerization initiators, etc. can be added to the reaction vessel by charging all of the monomer components into the reaction vessel and adding the polymerization initiator into the reaction vessel. Method of performing polymerization; charging a part of the monomer component into the reaction vessel, and adding the polymerization initiator and the remaining monomer component into the reaction vessel; copolymerizing; charging the reaction vessel with the polymerization solvent A method of adding the whole amount of the monomer and the polymerization initiator is preferable. Among these methods, the molecular weight distribution of the resulting polymer can be narrowed (sharpened), and cement water-reducing can be improved, which is an effect of increasing the fluidity of the cement composition, etc. It is preferable to perform copolymerization by a method in which an agent and a monomer are successively dropped into a reaction vessel.
In the above copolymerization method, the copolymerization conditions such as the copolymerization temperature are appropriately determined depending on the copolymerization method used, the solvent, the polymerization initiator, and the chain transfer agent, but the copolymerization temperature is usually 5 ° C. or higher. It is preferable that it is 150 degrees C or less. More preferably, it is 40 degreeC or more, More preferably, it is 45 degreeC or more, Most preferably, it is 50 degreeC or more. Further, it is more preferably 120 ° C. or lower, further preferably 100 ° C. or lower, and particularly preferably 85 ° C. or lower.
The polymer obtained by the above copolymerization method is used as it is as a main component of the cement additive, but may be further neutralized with an alkaline substance if necessary. As the alkaline substance, it is preferable to use inorganic salts such as hydroxides, chlorides and carbonates of monovalent metals and divalent metals; ammonia; organic amines.

The total amount of the copolymer (A) and the copolymer (B) in the cement admixture may be appropriately adjusted according to the desired water reduction performance. For example, the cement admixture 100 in terms of solid content. It is preferable that it is 50 mass% or more in mass%. More preferably, it is 60 mass% or more, More preferably, it is 70 mass% or more, Most preferably, it is 80% or more.
The above-mentioned cement admixture can be appropriately added with additives such as antifoaming agents and other polymers, compounds, etc. as necessary so that various performances can be exhibited as a cement admixture. . The cement admixture may be used in the form of an aqueous solution, or after the reaction, neutralized with a divalent metal hydroxide such as calcium or magnesium to obtain a polyvalent metal salt, and then dried. It is supported by an inorganic powder such as silica-based fine powder and dried, or is pulverized after being dried and solidified into a thin film on a support using a drum-type drying device, a disk-type drying device or a belt-type drying device, It may be used after being powdered by drying and solidifying with a spray dryer. Also, the powdered cement admixture of the present invention is blended in advance with a water-free cement composition such as cement powder or dry mortar, and used as a premix product for plastering, floor finishing, grout, etc. Alternatively, it may be blended when the cement composition is kneaded. The cement admixture may be used in combination with other cement admixtures. Other cement admixtures include, for example, conventional cement dispersants, air entrainers, cement wetting agents, swelling agents, waterproofing agents, retarders, quick setting agents, water-soluble polymeric substances, thickeners, flocculants, Examples thereof include a drying shrinkage reducing agent, a strength enhancer, a curing accelerator, and an antifoaming agent. Thus, the cement admixture may contain components other than the polymer.

The cement admixture can be used in combination with a known cement dispersant, and a plurality of known cement dispersants can be used in combination. When a known cement dispersant is used, the blending mass ratio between the cement admixture of the present invention and the known cement dispersant is unambiguous depending on the type, blending, and test conditions of the known cement dispersant used. Although it is not decided, 1-99 / 99-1 are preferable, 5-95 / 95-5 are more preferable, and 10-90 / 90-10 are still more preferable. As the known cement dispersant used in combination, a sulfonic acid-based dispersant (S) having a sulfonic acid group in the molecule is preferable. By using together with the sulfonic acid-based dispersant (S) having a sulfonic acid group in the molecule, it has high dispersion retention, and the cement brand and lot no. Regardless of this, it becomes a cement admixture that exhibits stable water reduction performance. The sulfonic acid-based dispersant (S) is a dispersant that exhibits water reduction for cement due to electrostatic repulsion mainly caused by sulfonic acid groups, and various known sulfonic acid-based dispersants can be used. A compound having an aromatic group in the molecule is preferable. Specifically, polyalkylaryl sulfonates such as naphthalene sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate, anthracene sulfonic acid formaldehyde condensate; melamine formalin resin sulfonate such as melamine sulfonic acid formaldehyde condensate Aromatic aminosulfonates such as aminoaryl sulfonic acid-phenol-formaldehyde condensates; lignin sulfonates such as lignin sulfonates and modified lignin sulfonates; various sulfonic acids such as polystyrene sulfonates System dispersants. In the case of concrete with a high water / cement ratio, a lignin sulfonate-based dispersant is preferably used, while in the case of a concrete with a moderate water / cement ratio that requires higher water reduction performance, Dispersants such as alkylaryl sulfonate, melamine formalin sulfonate, aromatic amino sulfonate, and polystyrene sulfonate are preferably used. Two or more sulfonic acid-based dispersants (S) having a sulfonic acid group in the molecule may be used in combination.

The polymer components (copolymer (A) and copolymer (B)) in the cement admixture of the present invention and the sulfonic acid-based dispersant (S) having a sulfonic acid group in the molecule are cement. Before kneading the composition, an aqueous solution in which each is dissolved in advance may be added to the cement, or each aqueous solution may be added to the cement when the cement composition is kneaded. Each powdered product may be added to the cement when the cement composition is kneaded, and any aqueous solution and powdered product may be added to the cement when the cement composition is kneaded. .

The blending ratio of the cement admixture of the present invention and the sulfonic acid-based dispersant (S) having a sulfonic acid group in the molecule, that is, (each polymer component in the cement admixture (copolymer (A), The total amount of the combined (B)) / sulfonic acid dispersant (S)) (% by mass) is the cement admixture of the present invention used together with the sulfonic acid dispersant (S) having a sulfonic acid group in the molecule. The optimum ratio varies depending on the performance balance, but is preferably 1 to 99/99 to 1, more preferably 5 to 95/95 to 5, and still more preferably 10 to 90/90 to 10.

The blending ratio of the cement admixture of the present invention and the cement admixture containing the sulfonic acid-based dispersant (S) having a sulfonic acid group in the molecule as an essential component and cement is, for example, mortar using hydraulic cement. In the case of using it for concrete or concrete, the content is preferably 0.01 to 10.0% of the cement mass. More preferably, it is 0.02-5.0%, More preferably, it is 0.05-2.0%.

If the water / cement ratio is relatively high and particularly high water reduction performance is not required, the copolymer (A) or the copolymer (B) and a sulfonic acid-based dispersant having a sulfonic acid group in the molecule ( A cement admixture containing S) as an essential component is also suitable.

The cement admixture can be used for various hydraulic materials, that is, cement compositions such as cement and gypsum and other hydraulic materials. Specific examples of a hydraulic composition containing such a hydraulic material, water, and the cement admixture of the present invention, and further containing fine aggregate (sand, etc.) and coarse aggregate (crushed stone, etc.) as necessary. Examples thereof include cement paste, mortar, concrete, and plaster. Among the hydraulic compositions, a cement composition that uses cement as the hydraulic material is the most common, and the cement composition contains the cement admixture of the present invention, cement, and water as essential components. Such a cement composition is one of the preferred embodiments of the present invention.

The cement used in the cement composition is not particularly limited. Specifically, for example, Portland cement (ordinary, early strength, very early strength, moderate heat, sulfate resistance, and low Alkali type), various mixed cements (blast furnace cement, silica cement, fly ash cement), white Portland cement, alumina cement, super fast cement (1 clinker fast cement, 2 clinker fast cement, magnesium phosphate cement), for grout Cement, oil well cement, low exothermic cement (low exothermic blast furnace cement, fly ash mixed low exothermic blast furnace cement, high content belite cement), ultra-high strength cement, cement-based solidified material, eco-cement (city waste incineration ash, sewage Cement produced from one or more types of sludge incineration ash) And the like. Furthermore, fine powder such as blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, silica fume, silica powder, limestone powder, or gypsum may be added to the cement composition. Aggregates include gravel, crushed stone, granulated slag, recycled aggregate, etc., as well as silica, clay, zircon, high alumina, silicon carbide, graphite, chrome, chromia, magnesia Refractory aggregates such as can be used.

In the above cement composition, unit water per Part 1 m ^3, a cement amount and water / cement ratio (mass ratio), unit water is preferably 100 kg / ^{m 3} or more, 185 kg / ^{m 3} or less, more preferably 120kg / M ³ or more and 175 kg / m ³ or less, and the amount of cement used is preferably 200 kg / m ³ or more and 800 kg / m ³ or less, more preferably 250 kg / m ³ or more and 800 kg / m ³ or less, The cement ratio (mass ratio) is preferably 0.1 or more and 0.7 or less, more preferably 0.2 or more and 0.65 or less, and it can be used widely from poor blending to rich blending. The cement admixture has a high water reduction rate region, that is, a water / cement ratio such as a water / cement ratio (mass ratio) of 0.15 or more and 0.5 or less (preferably 0.15 or more and 0.4 or less). It can be used in a low region, and is effective for both high-strength concrete having a large unit cement amount and a small water / cement ratio, and poor blended concrete having a unit cement amount of 300 kg / m ³ or less.

In the cement composition, the blending amount of the cement admixture, for example, when used for mortar or concrete using hydraulic cement, is preferably 0.01 relative to the mass of the cement in terms of solid content. % By mass or more, 10.0% by mass or less, more preferably 0.02% by mass or more and 5.0% by mass or less, more preferably 0.03% by mass or more and 3.0% by mass or less, particularly preferably 0% by mass. 0.05% by mass or more and 2.0% by mass or less. Such a blending amount brings various preferable effects such as a reduction in unit water amount, an increase in strength, and an improvement in durability. If the blending amount of the cement admixture is less than 0.01% by mass, the water reducing performance may not be sufficiently exhibited. On the contrary, when the blending amount of the cement admixture exceeds 10.0% by mass, the effect of improving water reduction is substantially saturated, and the cement admixture is used more than necessary. Cost may increase.

The cement composition has high water-reducing properties and water-retaining properties even in a high water-reducing rate region, and exhibits sufficient initial water-reducing properties and viscosity-reducing properties even at low temperatures, and has excellent workability. To ready-mixed concrete, concrete for concrete secondary products (precast concrete), concrete for centrifugal molding, concrete for vibration compaction, steam-cured concrete, shotcrete, etc. Is required to have high fluidity such as high-fluidity concrete (slump value of 25 cm or more, slump flow value of 50 cm or more and 70 cm or less), self-filling concrete, self-leveling material, etc. Mortar or concrete It is also effective.

Furthermore, the cement composition of the present invention may contain other known cement additives (materials) as exemplified in the following (1) to (20).
(1) Water-soluble polymer substance: unsaturated carboxylic acid polymer such as polyacrylic acid (sodium), polymethacrylic acid (sodium), polymaleic acid (sodium), sodium salt of acrylic acid / maleic acid copolymer; methyl Nonionic cellulose ethers such as cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, and hydroxypropyl cellulose; polysaccharides such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose A part of or all of the hydroxyl groups of the alkylated or hydroxyalkylated derivatives of the above are a hydrophobic substituent having a hydrocarbon chain having 8 to 40 carbon atoms as a partial structure, a sulfonic acid group or Polysaccharide derivatives substituted with an ionic hydrophilic substituent containing such a salt as a partial structure; yeast glucan, xanthan gum, β-1.3 glucans (both linear and branched) For example, polysaccharides produced by microbial fermentation such as curdlan, paramylon, pachyman, scleroglucan, laminaran, etc.); polyacrylamide; polyvinyl alcohol; starch; starch phosphate ester; sodium alginate; gelatin; Copolymers of acrylic acid having groups and quaternary compounds thereof.

(2) Polymer emulsion: Copolymers of various vinyl monomers such as alkyl (meth) acrylate.
(3) retarder: oxycarboxylic such as gluconic acid, glucoheptonic acid, arabonic acid, malic acid or citric acid, and inorganic salts or organic salts thereof such as sodium, potassium, calcium, magnesium, ammonium, triethanolamine, etc. Acid; monosaccharides such as glucose, fructose, galactose, saccharose, xylose, apiose, ribose, isomerized sugar, oligosaccharides such as disaccharide and trisaccharide, oligosaccharides such as dextrin, polysaccharides such as dextran, etc. Sugars such as molasses; sugar alcohols such as sorbitol; magnesium silicofluoride; phosphoric acid and its salts or borate esters; aminocarboxylic acids and salts thereof; alkali-soluble proteins; humic acid; tannic acid; Polyhydric alcohols such as glycerin; aminotri (methylenephos Acid), 1-hydroxyethylidene-1,1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and their alkali metal salts, alkaline earth metal salts and other phosphonic acids and their derivatives etc.

(4) Early strengthening agents / accelerators: soluble calcium salts such as calcium chloride, calcium nitrite, calcium nitrate, calcium bromide and calcium iodide; chlorides such as iron chloride and magnesium chloride; sulfates; potassium hydroxide; Sodium hydroxide; carbonate; thiosulfate; formate such as formic acid and calcium formate; alkanolamine; alumina cement; calcium aluminate silicate.
(5) Mineral oil-based antifoaming agent: cocoon oil, liquid paraffin, etc.
(6) Fat and oil-based antifoaming agents: animal and vegetable oils, sesame oil, castor oil, alkylene oxide adducts thereof and the like.
(7) Fatty acid-based antifoaming agent: oleic acid, stearic acid, and these alkylene oxide adducts.
(8) Fatty acid ester antifoaming agent: glycerin monoricinoleate, alkenyl succinic acid derivative, sorbitol monolaurate, sorbitol trioleate, natural wax and the like.
(9) Oxyalkylene antifoaming agents: polyoxyalkylenes such as (poly) oxyethylene (poly) oxypropylene adducts; diethylene glycol heptyl ether, polyoxyethylene oleyl ether, polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene (Poly) oxyalkyl ethers such as 2-ethylhexyl ether and oxyethyleneoxypropylene adducts to higher alcohols having 12 to 14 carbon atoms; (poly) oxy such as polyoxypropylene phenyl ether and polyoxyethylene nonylphenyl ether Alkylene (alkyl) aryl ethers; 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2,5-dimethyl-3-hexyne-2,5-diol, 3-methyl-1 − Acetylene ethers obtained by addition polymerization of alkylene oxide to acetylenic alcohol such as tin-3-ol; (poly) oxyalkylene fatty acid esters such as diethylene glycol oleate, diethylene glycol laurate, ethylene glycol distearate; polyoxyethylene (Poly) oxyalkylene sorbitan fatty acid esters such as sorbitan monolaurate and polyoxyethylene sorbitan trioleate; (poly) oxyalkylene alkyls such as sodium polyoxypropylene methyl ether sulfate and sodium polyoxyethylene dodecylphenol ether sulfate ( Aryl) ether sulfate salts; (poly) oxyethylene stearyl phosphates, etc. Sialic sharp emission alkyl phosphate esters; polyoxyethylene such as polyoxyethylene lauryl amine (poly) oxyalkylene alkyl amines; polyoxyalkylene amide.

(10) Alcohol-based antifoaming agent: octyl alcohol, hexadecyl alcohol, acetylene alcohol, glycols and the like.
(11) Amide antifoaming agent: acrylate polyamine and the like.
(12) Phosphate ester antifoaming agent: tributyl phosphate, sodium octyl phosphate, etc.
(13) Metal soap type antifoaming agent: aluminum stearate, calcium oleate, etc.
(14) Silicone antifoaming agent: dimethyl silicone oil, silicone paste, silicone emulsion, organically modified polysiloxane (polyorganosiloxane such as dimethylpolysiloxane), fluorosilicone oil and the like.

(15) AE agent: resin soap, saturated or unsaturated fatty acid, sodium hydroxystearate, lauryl sulfate, ABS (alkyl benzene sulfonic acid), LAS (linear alkyl benzene sulfonic acid), alkane sulfonate, polyoxyethylene alkyl (phenyl) ether , Polyoxyethylene alkyl (phenyl) ether sulfate or a salt thereof, polyoxyethylene alkyl (phenyl) ether phosphate or a salt thereof, protein material, alkenyl sulfosuccinic acid, α-olefin sulfonate, and the like.

(16) Other surfactants: aliphatic monohydric alcohols having 6 to 30 carbon atoms in the molecule such as octadecyl alcohol and stearyl alcohol, and those having 6 to 30 carbon atoms in the molecule such as abiethyl alcohol Intramolecular such as alicyclic monohydric alcohol, dodecyl mercaptan, etc. Intramolecular such as monovalent mercaptan having 6-30 carbon atoms in the molecule, such as nonylphenol, alkylphenol having 6-30 carbon atoms in the molecule, dodecylamine, etc. 10 mol or more of an alkylene oxide such as ethylene oxide or propylene oxide was added to a carboxylic acid having 6 to 30 carbon atoms in the molecule such as an amine having 6 to 30 carbon atoms, lauric acid or stearic acid. Polyalkylene oxide derivatives having an alkyl or alkoxy group as a substituent Alkyl diphenyl ether sulfonates in which two phenyl groups having a sulfone group are ether-bonded; various anionic surfactants; various cationic surfactants such as alkylamine acetate and alkyltrimethylammonium chloride; various nonionics Surfactant; various amphoteric surfactants.
(17) Waterproofing agent: fatty acid (salt), fatty acid ester, oil and fat, silicon, paraffin, asphalt, wax and the like.
(18) Rust preventive: nitrite, phosphate, zinc oxide and the like.
(19) Crack reducing agent: polyoxyalkyl ether and the like.
(20) Expansion material: Ettlingite, coal, etc.

Other known cement additives (materials) include cement wetting agents, thickeners, separation reducing agents, flocculants, drying shrinkage reducing agents, strength enhancers, self-leveling agents, rust preventives, colorants, and antifungal agents. An agent etc. can be mentioned. The known cement additives (materials) can be used in combination.

In the cement composition of the present invention, the following 1) to 4) are particularly preferable embodiments for components other than cement and water.
1) A combination comprising two components, (1) the cement admixture of the present invention and (2) an oxyalkylene antifoaming agent. The blending mass ratio of the oxyalkylene antifoaming agent (2) is preferably 0.01 to 10% by mass with respect to the cement admixture (1).

2) A combination comprising two components: (1) the cement admixture of the present invention and (2) a material separation reducing agent. As a material separation reducing agent, various thickeners such as nonionic cellulose ethers, a hydrophobic substituent consisting of a hydrocarbon chain having 4 to 30 carbon atoms as a partial structure and an alkylene oxide having 2 to 18 carbon atoms are added on average. A compound having a polyoxyalkylene chain having 2 to 300 moles added can be used. The blending mass ratio of the cement admixture (1) and the material separation reducing agent (2) is preferably 10/90 to 99.99 / 0.01, and 50/50 to 99.9 / 0.0. 1 is more preferable. A cement composition comprising this combination is suitable as high fluidity concrete, self-filling concrete, and self-leveling material.

3) (1) The cement admixture of the present invention and (2) a combination comprising two components of retarder. As the retarder, oxycarboxylic acids such as gluconic acid (salt) and citric acid (salt), sugars such as glucose, sugar alcohols such as sorbitol, phosphonic acids such as aminotri (methylenephosphonic acid), and the like can be used. . The blending mass ratio of the cement admixture (1) and the retarder (2) is preferably 50/50 to 99.9 / 0.1, more preferably 70/30 to 99/1.

4) A combination comprising two components, (1) the cement admixture of the present invention and (2) an accelerator. As the accelerator, soluble calcium salts such as calcium chloride, calcium nitrite and calcium nitrate, chlorides such as iron chloride and magnesium chloride, formates such as thiosulfate, formic acid and calcium formate, and the like can be used. The blending mass ratio of the cement admixture (1) and the accelerator (2) is preferably 10/90 to 99.9 / 0.1, more preferably 20/80 to 99/1.

The present invention is also a method for producing the cement admixture.
In the said manufacturing method, components, such as a copolymer (A) and a copolymer (B), can be performed according to the method described in the said cement admixture, Moreover, the said manufacturing method is other normal. Can be done by the method.

The cement admixture of the present invention has the above-described configuration, and has excellent water reduction performance, particularly in a region where a high performance AE water reducing agent or AE water reducing agent is used (water / cement weight ratio = 0.3 to 0.6). It is a cement admixture with low slump retention and high usage.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “% by mass”.

(Reference Examples 1-16)
[Preparation of copolymer]
As the copolymer (A), copolymers (A-1) to (A-5) were prepared. As the copolymer (B), copolymers (B-1) to (B-6) were prepared. Furthermore, copolymers (C-1) to (C-5) were prepared as ester copolymers used in the comparative examples. For each copolymer, the composition ratio of the monomers used as raw materials and the adsorption rate to the Portland cement particles are shown in Table 1 below.
[Production Example of Copolymer (A-1)]
A reactor equipped with a thermometer, a stirrer, a dropping device, a nitrogen introduction tube and a cooling tube was charged with 333.7 g of ion-exchanged water and 463.9 g of an isoprenol ethylene oxide (EO) 50 mol adduct (IPN-50), The temperature was raised to 60 ° C. Subsequently, 2.43 g of a 30% aqueous hydrogen peroxide solution was added, and then an aqueous solution in which 62.7 g of acrylic acid was dissolved in 37.3 g of ion-exchanged water was added in 3 hours, and 0.94 g of L-ascorbic acid and 3- An aqueous solution in which 2.44 g of mercaptopropionic acid was dissolved in 96.6 g of ion-exchanged water was simultaneously added dropwise in 3.5 hours. Stirring was further continued for 1 hour after the dropping, and then a sodium hydroxide aqueous solution and water for concentration adjustment were added to obtain a polycarboxylic acid copolymer (A- An aqueous solution of 1) was obtained.

Table 1 will be described below. Abbreviations in the table represent the following matters.
IPN-25: 25 mol of EO added to isoprenol IPN-50: 50 mol of EO added to isoprenol MLA-50: 50 mol of EO added to methallyl alcohol MLA-100 : Methallyl alcohol with 100 mol EO added MLA-120: methallyl alcohol with 120 mol EO added PGM-25E: methoxypolyethylene glycol monomethacrylate (n = 25)
SA: sodium salt of acrylic acid SMAA: sodium salt of methacrylic acid HEA: 2-hydroxyethyl acrylate In addition, SA and SMAA which are monomers (b) constituting the copolymers (A) and (B) are for convenience. Although described as a sodium salt, the monomer used for the preparation of the polymer is not a sodium salt but acrylic acid or methacrylic acid. Copolymers (A) and (B) were prepared by synthesizing a copolymer using an acid-type monomer and then neutralizing with sodium hydroxide. For example, “IPN-50 / SA = 85.0 / 15.0” in Reference Example 1 in Table 1 means that 50 mol of isoprenol is present, as is apparent from the production example of the copolymer (A-1). The EO-added monomer was copolymerized with 85% by mass of acrylic acid in an amount corresponding to 15% by mass in terms of sodium salt of acrylic acid, and then neutralized with sodium hydroxide. Represents that the copolymer (A-1) was prepared. The same applies to Reference Example 2-16.

In addition, the adsorption rate of the copolymer (A), the copolymer (B), and the copolymer (C) in the above Table 1 was measured as follows. In a room adjusted to 25 ° C., first, a polymer is put in a beaker so that it becomes 0.1% by weight in terms of solid content with respect to 100% by mass of ordinary Portland cement, and water is further added to make a total of 100 g. Then, the mixture was stirred with a stirrer and dissolved uniformly. Next, 100 g (100% by weight in terms of water / cement ratio) of cement was added to the same beaker while stirring with a stirrer, and after stirring for 5 minutes, filtration was performed and a filtrate was collected. The amount of the polymer remaining in the obtained filtrate was measured with a differential refractometer. And the adsorption rate was calculated by the following formula.
Adsorption rate (%) = {[(area of copolymer on RI chart of 0.1% aqueous solution) − (area of copolymer on RI chart of cement filtrate after adsorption)] / ( Area of copolymer on RI chart of 0.1% aqueous solution}} × 100
In addition, normal Portland cement made by Taiheiyo Cement Co., Ltd. was used as the cement used in the adsorption rate test. In addition, as a differential refractometer, a 410 differential refractometer made by Japan Waters was used, and measurement was performed under the following GPC measurement conditions.

(GPC molecular weight measurement conditions)
Column used: TSK guard Column SWXL + TSKge1 G4000SWXL + G3000SWXL + G2000SWXL manufactured by Tosoh Corporation
Eluent: An eluent solution prepared by dissolving 115.6 g of sodium acetate trihydrate in a mixed solvent of 10999 g of water and 6001 g of acetonitrile and adjusting the pH to 6.0 with acetic acid is used.
Implanted amount: 0.1% aqueous solution or 100 μL of filtrate obtained by measuring adsorption rate
Eluent flow rate: 0.8 mL / min
Column temperature: 40 ° C
Standard substance: polyethylene glycol, peak top molecular weight (Mp) 272500, 219300, 85000, 46000, 24000, 12600, 4250, 7100, 1470
Calibration curve order: Tertiary detector: 410 manufactured by Waters, Japan 410 Differential refraction detector analysis software: MILRENNIUM Ver. Manufactured by Waters, Japan 3.21

The method for calculating the adsorption rate will be described with reference to the drawings, for example. FIG. 1 shows a cement admixture prepared in Reference Example 1 so as to be a 0.1% by mass aqueous solution of the copolymer (A-1) synthesized as the copolymer (A) using GPC. Although it is a figure which shows the measurement result, the part shown with an oblique line is an area for the copolymer on the RI chart of the said 0.1% aqueous solution. FIG. 2 is a diagram showing the results of measurement of the cement filtrate after adsorption on the copolymer (A-1) synthesized as the copolymer (A) in Reference Example 1, but indicated by hatching. The portion to be covered is the area of the copolymer on the RI chart of the cement filtrate after adsorption. If the area for the copolymer in FIGS. 1 and 2 is applied to the above formula, it becomes 64.2%, and the adsorption rate of the copolymer (A-1) can be calculated. The adsorption rate was calculated in the same manner for all examples and comparative examples.

[Concrete test]
(Example 1)
Ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd.) as cement, Oigawa water-based land sand and Kimitsu mountain sand (specific gravity 2.62, FM 2.71) as fine aggregate, Ome hard sandstone crushed stone (specific gravity) 2.64, MS 20 mm) was used. The amount of air was adjusted to 4 to 5% using a commercially available antifoaming agent as necessary. The cement admixture of the present invention prepared by mixing the copolymer (A-1) prepared in Reference Example 1 and the copolymer (B-1) prepared in Reference Example 6 at a mass ratio of 50:50 ( The test was conducted using 1). The concrete mixing conditions were as shown in Table 2 below.

Abbreviations in Table 2 above represent the following.
W / C (mass%): mass ratio of water (W) to cement (C) (mass%)
Fine aggregate ratio (volume%): Ratio of absolute volume of fine aggregate to absolute volume of total aggregate (volume%)
Cement (C): Ordinary Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.)
Coarse aggregate (G): Oigawa water system land sand and Chiba prefecture Kimitsu mountain sand (specific gravity 2.62, FM 2.71)
Fine aggregate (S): Ome hard sandstone crushed stone (specific gravity 2.64, MS20mm)

15 minutes after producing 50 liters of concrete using a pan-type forced kneading mixer under the blending conditions shown in Table 2 above and determining the amount of use so that the slump flow value immediately after kneading is 420 ± 20 mm. Thereafter, the slump flow value after 30 minutes was measured. The slump and air volume were all measured according to Japanese Industrial Standards (JIS A1101, 1128, 6204). The results are shown in Table 3-1 below.

(Examples 2 to 24)
Examples 2 to 24 were performed according to Example 1 except that cement admixtures containing copolymers shown in Table 3-1 below were used. The names of the copolymers used in each example and the test results are shown in Table 3-1 below.

(Comparative Examples 1-4)
As shown in Table 3-2 below, Comparative Examples 1 to 4 were performed according to Example 1 except that a cement admixture prepared using one type of copolymer was used. The names of the copolymers used in each comparative example and the test results are shown in Table 3-2 below.
(Comparative Examples 5-15)
Comparative Examples 5 to 15 were performed according to Example 1 except that a cement admixture containing a copolymer shown in Table 3-2 below was used. The names of the copolymers used in each comparative example and the test results are shown in Table 3-2 below.

The above Table 3-1 and Table 3-2 will be described below. In Table 3-1 and Table 3-2, the addition amount represents the mass ratio (%) of the copolymer to the ordinary Portland cement (in terms of solid content). The blending represents the mass ratio (%) of each copolymer in the mass of 100% of all copolymers. For example, the copolymer (A-1), the copolymer (A-2), the copolymer (B-1), and the copolymer (B-2) are the copolymers shown in Table 1 above. It is. For example, the cement admixture of Example 1 means that the copolymer (A-1) and the copolymer (B-1) are contained at a mass ratio of 50:50.
In Table 3-1 and Table 3-2 above, the adsorption rate (%) represents the adsorption rate of each copolymer used in the cement admixtures of Examples and Comparative Examples. For example, the cement admixture of Example 1 is described as 64.2 / 32.7 in Table 3-1, which indicates that the adsorption rate of the copolymer (A-1) is 64.2. %, Which means that the adsorption rate of the copolymer (B-1) is 32.7%.
In Table 3-1 and Table 3-2 above, the average adsorption rate means the average value of the adsorption rate of the copolymer. For example, in the cement admixture of Example 1, 50% of the copolymer (A-1) having an adsorption rate of 64.2% and the copolymer (B-1) having an adsorption rate of 32.7%: In this case, the average adsorption rate is (64.2 × 50/100) + (32.7 × 50/100) = 48.5%. The average adsorption rate in Comparative Example 1-4 using one type of copolymer is the adsorption rate of each copolymer. Other examples and comparative examples are the same as above.
In Table 3-1 and Table 3-2 above, the difference in adsorption rate represents the difference in adsorption rate between the two types of copolymers. For example, the cement admixture of Example 1 includes a copolymer (A-1) having an adsorption rate of 64.2% and a copolymer (B-1) having an adsorption rate of 32.7%. However, the difference in adsorption rate in this case is 64.2-32.7 = 31.5%. Other examples and comparative examples are the same as above.
The water reduction in the above Table 3-1 and Table 3-2 was evaluated by the addition amount of cement admixture necessary for the slump flow value immediately after kneading to be 420 ± 20 mm. A smaller amount of cement admixture means better water reduction. The water reduction evaluation and slump retention evaluation in Tables 3-1 and 3-2 were performed based on Table 4 below.

Regarding the above test, in the graph in which the vertical axis is the adsorption rate of the “copolymer having an adsorption rate of 40% or more” and the horizontal axis is the adsorption rate of the “copolymer having an adsorption rate of less than 40%”, What plotted the Example and the comparative example is shown in FIG. By associating the adsorption rate distribution in FIG. 7 with the results of Tables 3-1 and 3-2 above, the critical significance of specifying the adsorption rate as described above in the present invention is clear.

From the above Table 3-1 and Table 3-2, the water reduction performance and slump retention of concrete using the cement admixture of the present invention are, for example, substantially the same adsorption rate as the average adsorption rate of Example 2 and Example 2. When compared with Comparative Example 3 having The same applies to the comparison between Example 1 and Comparative Example 2. This shows the performance improvement by blending. Comparative Example 5, which is an (alkoxy) polyalkylene glycol mono (meth) acrylic acid ester type, is almost equivalent to the average adsorption rate of Example 1, and a copolymer having an adsorption rate of 40% or more and a copolymer having a adsorption rate of less than 40%. Although it contains a polymer, the water-reducing property and slump retention property are inferior. The same applies to the relationship between Example 11 and Comparative Example 8 and the relationship between Example 14 and Comparative Example 9. Therefore, it can be seen that the above-described effects of the present invention are peculiar to the (poly) alkylene glycol monoalkenyl ether system. That is, it can be said that the above-described remarkable effect is exhibited in a cement admixture including a copolymer that essentially includes a (poly) alkylene glycol monoalkenyl ether monomer unit.

In Table 3-1 and Table 3-2 above, for example, Comparative Examples 7, 10, 11, 12, and 13 are cements containing two types of copolymers (B) having an adsorption rate of less than 40%. Although they are admixtures, they are clearly inferior in water reduction compared to the examples. Further, for example, Comparative Examples 6, 14, and 15 are cement admixtures containing two types of copolymers (A) having an adsorption rate of 40% or more, but these are slumps as compared with Examples. It is clear that the retention is inferior. Accordingly, by including both the copolymer (A) having an adsorption rate of 40% or more and the copolymer (B) having an adsorption rate of less than 40%, two water reduction performances and slump retention properties can be obtained. It was confirmed that the balance of performance was excellent.

It is IR chart which measured the cement admixture which made the copolymer (A-1) 0.1 mass% aqueous solution in Reference Example 1 using GPC. It is IR chart which added the cement admixture which made the copolymer (A-1) the 0.1 mass% aqueous solution to the cement in Reference Example 1, and measured the aqueous solution after 5 minutes using GPC. In Reference example 2, it is IR chart which measured the cement admixture which made the copolymer (A-2) 0.1 mass% aqueous solution using GPC. It is IR chart which added the cement admixture which made the copolymer (A-2) the 0.1 mass% aqueous solution to the cement in Reference Example 2, and measured the aqueous solution after 5 minutes using GPC. In Reference example 7, it is IR chart which measured the cement admixture which made the copolymer (B-2) 0.1 mass% aqueous solution using GPC. In Reference Example 7, it is an IR chart obtained by adding a cement admixture in which a copolymer (B-2) is a 0.1% by mass aqueous solution to cement and measuring the aqueous solution after 5 minutes using GPC. In the graph in which the vertical axis represents the adsorption rate of the “copolymer with an adsorption rate of 40% or more” and the horizontal axis represents the adsorption rate of the “copolymer with an adsorption rate of less than 40%”, Examples of the present invention and comparison It is the figure which plotted the example.

Claims (2)

A cement admixture comprising at least two types of copolymers,
The cement admixture is
The following general formula (1);

(In the formula, R ¹ O represents one or more of oxyalkylene groups having 2 to 18 carbon atoms. M represents the average number of added moles of oxyalkylene groups, and represents the number of 1 to 500. R ² represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and Y represents an alkenyl group having 2 to 8 carbon atoms. It includes a copolymer (A) and a copolymer (B) containing a structural unit derived from an ether monomer (a) and a structural unit derived from an unsaturated carboxylic acid monomer (b). ,
The copolymer (A) has an adsorption rate on cement particles of 40% or more,
The cement admixture characterized in that the copolymer (B) has an adsorption rate to cement particles of less than 40%. The cement according to claim 1, wherein the difference between the adsorption rate of the copolymer (A) to cement particles and the adsorption rate of the copolymer (B) to cement particles is 5% or more. Admixture.

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