JP2008105867A - Cement admixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement admixture sufficiently applicable even to a cement composition having super-high strength, and having high economical efficiency because of a small quantity consumed. <P>SOLUTION: The cement admixture comprises a copolymer including a constitutional unit derived from a polyalkylene glycol monoalkenyl ether monomer (a) expressed by general formula: YO-R<SP>1</SP>O<SB>m</SB>-R<SP>2</SP>, and a constitutional unit derived from an unsaturated carboxylic acid monomer (b) wherein the copolymer has not less than 40% of an adsorption coefficient to cement particles. In the formula, R<SP>1</SP>O, m, R<SP>2</SP>, and Y represent at least one member of 2-18C oxyalkylene groups, an average added mole number which is within the range of 1-500, a hydrogen atom or a 1-30C hydrocarbon group, and a 2-8C alkenyl group respectively. <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 is used (water / cement weight ratio = 0.2 to 0.45), a material having both excellent water reducing 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 present invention has been made in view of the above-mentioned present situation, and the object of the present invention is to improve the above-mentioned problems, can be sufficiently applied to a cement composition having ultra-high strength, and has a small amount of use and is economical. It is to provide a cement admixture with a high content.

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 copolymer, the cost performance is improved as compared with the (alkoxy) polyalkylene glycol mono (meth) acrylic acid ester, and the copolymer has an adsorption rate to the cement particles of 40% or more. Thus, the present inventors have found that excellent water reduction performance appears and have reached the present invention. In addition, about the measuring method of the adsorption rate to the cement particle of a copolymer, 0.1 weight% of copolymers are added to a cement in conversion of solid content so that it may mention later, and it measures after 5 minutes at 25 degreeC. It is preferable.
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, the effect of maintaining fluidity is high even when the adsorption rate is high in the relationship between the adsorption rate and the fluidity. 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.

That is, the present invention provides 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. A cement admixture comprising a copolymer comprising a structural unit derived from an ether monomer (a) and a structural unit derived from an unsaturated carboxylic acid monomer (b), wherein the copolymer Is a cement admixture having an adsorption rate on cement particles of 40% or more.
The present invention is described in detail below.

The copolymer comprises a structural unit derived from a (poly) alkylene glycol monoalkenyl ether monomer (a) (hereinafter sometimes simply referred to as monomer (a)), an unsaturated carboxylic acid monomer. And a structural unit derived from the body (b) (hereinafter sometimes simply referred to as the monomer (b)). That is, the copolymer has a structural unit of the (poly) alkylene glycol monoalkenyl ether monomer (a) and a structural unit derived from the unsaturated carboxylic acid monomer (b).
The copolymer may have a structure other than the structural unit derived from the monomer (a) and the structural unit derived from the monomer (b), but is derived from the monomer (a). The structural unit and the structural unit derived from the monomer (b) are preferably the 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% by mass or more, more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably, the structural unit substantially derived from the monomer (a) and the monomer (B) It consists of a structural unit derived from.

In addition, when 2 or more types of copolymers are contained, any 1 type of copolymer should just satisfy the conditions of the said copolymer. Even in such a case, the copolymer is present in the cement admixture, and the effect of the present invention is exhibited by the copolymer having an adsorption rate of 40% or more. In this case, it is preferable that the copolymer having an adsorption rate of 40% or more becomes a main component in the entire copolymer exhibiting water reducing performance in the cement admixture. It is preferable that substantially all of the copolymers are constituted by a copolymer having the above-described adsorption rate of 40% or more. For example, as long as the effects of the present invention can be obtained, The amount of the copolymer having an adsorption rate of 40% or more is preferably 50% by mass or more. More preferably, it is 80 mass% or more, More 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 4 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 described above is composed mainly of ethylene oxide, so that the hydrophilicity of the copolymer is appropriately improved, By adsorbing to the cement particles, it is possible to sufficiently exhibit the effect of water reduction.
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.

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 cement water reduction performance, 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. 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 of the copolymer 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 above copolymer, 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 (poly) It is preferable to carry out the process by appropriately adjusting the average number of moles of alkylene oxide groups that the alkylene glycol monoalkenyl ether monomer (a) has.
What is necessary is just to prepare the copolymer whose said adsorption rate is 40% or more, ie, the said copolymer, with a form like following (1)-(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 said embodiment (1)-(4) is an illustration of the method which can prepare the said copolymer suitably, Comprising: It is not restricted to these forms. 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.

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, MILRENNIUM manufactured by Japan Waters Co., Ltd. Ver. 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 in the case of other cement particles, if the cation is present on the surface of the cement particles and is positively charged, the adsorption rate is sufficient due to the structure of the copolymer. The effect of can be demonstrated.
As described above, if the copolymer has an adsorption rate of 40% or more, it is possible to obtain a cement admixture having excellent water reduction performance, low usage, and high economic efficiency. It can be said that there is a feature.
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 a copolymer whose adsorption rate to cement particles at 0 ° C. is as described above, and it is particularly preferable to apply to a cement composition composed of ordinary Portland cement. Regardless of the type of cement, that is, other than ordinary Portland cement having the above-mentioned characteristics, and compositions composed of other cements, etc., a cement composition that uses a cement admixture (mortar , So-called cement compositions including concrete, etc.). 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.

The inventors of the present invention adsorbed the copolymer to the cement particles more rapidly as the molecular weight becomes higher. After the high molecular weight adsorbed to the cement particles, the low molecular weight adsorbed sequentially over time. I found it going. The weight average molecular weight of the copolymer has less influence on the adsorption rate than the acid amount. The smaller the acid amount, the less the influence of the weight average molecular weight on the adsorption rate increases.
The weight average molecular weight of the copolymer is a structure derived from the (poly) alkylene glycol monoalkenyl ether monomer (a) constituting the copolymer, in particular, the average added mole number of the alkylene oxide group, the acid amount, and the like. The weight average molecular weight of the copolymer is preferably 20000 or more, although it is not uniquely determined due to the difference in the above. More preferably, it is 30000 or more, More preferably, it is 40000 or more.
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

One of the preferred embodiments of the present invention is that the adsorption rate is 45% or more.
Since the desired fluidity and slump value can be obtained with a small amount of use when the adsorption rate to ordinary Portland cement particles after 45 minutes from the addition of the copolymer is 45% or more, excellent water reduction performance is obtained. It will be demonstrated more.
The adsorption rate to ordinary Portland cement particles after 5 minutes from the addition of the copolymer is preferably 50% or more. More preferably, it is 55% or more, still more preferably 60% or more, and particularly preferably 65% or more.

As a method for preparing the copolymer, for example, a monomer component and a polymerization initiator can be used by a usual polymerization method such as solution polymerization or bulk polymerization. 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 of the resulting copolymer can be easily adjusted. 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.

What is necessary is just to adjust suitably the compounding quantity of the said copolymer in the said cement admixture according to desired water reduction performance, for example, it is 50 mass% or more in 100 mass% of cement admixtures in conversion of solid content. Is preferred. 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 a sulfonic acid-based dispersant (S) having a sulfonic acid group in the molecule, it has high water-retaining properties, and has a 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 medium water / cement ratio that requires higher dispersion 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 component in the cement admixture of the present invention and the sulfonic acid-based dispersant (S) having a sulfonic acid group in the molecule are prepared by dissolving an aqueous solution in which each of the polymer components is previously dissolved before the cement composition is kneaded. Each aqueous solution may be added to the cement at the time of kneading the cement composition, each powdered formulation may be added to the cement, and each aqueous solution at the time of kneading the cement composition. The powdered product may be added to the cement, 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, (the blended amount of the copolymer in the cement admixture / sulfonic acid-based dispersant ( S)) (mass%) is an optimum ratio depending on the performance balance between the cement admixture of the present invention to be used together and the sulfonic acid-based dispersant (S) having a sulfonic acid group in the molecule. 99-1 are preferable, 5-95 / 95-5 are more preferable, and 10-90 / 90-10 are still more preferable.

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%.

When the water / cement ratio is relatively high and particularly high water reduction performance is not required, a cement containing the copolymer and a sulfonic acid-based dispersant (S) having a sulfonic acid group in the molecule as essential components. Admixtures are 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.

The cement composition of the present invention is also effective for ready-mixed concrete, concrete for concrete secondary products (precast concrete), centrifugal molded concrete, vibration compacted concrete, steam-cured concrete, shotcrete, etc. High fluidity is required for fluidized concrete (concrete with a slump value of 22 to 25 cm), high fluidity concrete (concrete with a slump value of 25 cm or more and a slump flow value of 50 to 70 cm), self-filling concrete, self-leveling material, etc. It is also effective for mortar and concrete.

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 alkyl 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, structural components, such as the said copolymer, can be prepared according to the method described in the said cement admixture. Moreover, in the said manufacturing method, it can carry out by another normal method.

The cement admixture of the present invention has the above-described configuration, and has excellent water reducing performance, particularly in a region where a high performance AE water reducing agent is used (water / cement weight ratio = 0.2 to 0.45). It is a cement admixture with a small amount and high economic efficiency.

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”.

[Preparation of copolymer]
(Reference Example 1-4 and Comparative Reference Example 1-3)
A copolymer of Reference Example 1-4 was prepared as a copolymer having an adsorption rate of 40% or more. Moreover, the copolymer of Comparative Reference Example 1-3 was prepared as a copolymer having the adsorption rate of less than 40%. 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.

Table 1 will be described below. Abbreviations in the table represent the following matters.
IPN-50: 50 mol EO added to isoprenol MLA-50: 50 mol EO added to methallyl alcohol MLA-100: 100 mol EO added to methallyl alcohol MLA -150: 150 mol of EO added to methallyl alcohol PGM-25E: methoxypolyethylene glycol monomethacrylate (n = 25)
SA: sodium salt of acrylic acid SMAA: sodium salt of methacrylic acid

In addition, the adsorption rate of the copolymer in the said 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 is a diagram showing the results of measuring the cement admixture prepared in Reference Example 1 so as to be a 0.1% by mass aqueous solution of the copolymer using GPC. This is the area of the copolymer on the RI chart of the 0.1% aqueous solution. FIG. 2 is a diagram showing the results of measurement of the cement filtrate after adsorption in Reference Example 1, where the hatched portion is the area of the copolymer on the RI chart of the cement filtrate after adsorption. It is. When the area for the copolymer in FIGS. 1 and 2 is applied to the above formula, it is 64.2%, and the adsorption rate of the copolymer used in Example 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) as cement, Oikawa 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).
The concrete mixing conditions were as shown in Table 2 below. The amount of air was adjusted to 1 to 2% using a commercially available antifoaming agent as necessary.

Under the blending conditions shown in Table 2 above, 50 liters of concrete was produced using a biaxial forced kneading mixer, and the slump flow value when the initial usage amount was 0.2% was measured. The slump flow value and the amount of air were all measured according to Japanese Industrial Standards (JIS A1101, 1128, 6204). The evaluation of slump flow value and water reduction is shown in Table 3 below.
(Example 2 and Comparative Example 1-5)
The same procedure as in Example 1 was performed except that the conditions were changed as shown in Table 3 below. These results are shown in Table 3 below.

Table 3 will be described below. In Table 3 above, the addition amount represents the mass ratio (%) of the copolymer to the ordinary Portland cement (in terms of solid content). The names of the cement admixtures described in Table 3 above correspond to the names of the cement admixtures described in Table 1, respectively. The water reduction evaluation in Table 3 was performed based on Table 4 below.

From Table 3 above, it can be seen that the water reduction of concrete using the cement admixture of the present invention is improved compared to the comparative cement admixture. In addition, the comparative cement admixture (3), which is an (alkoxy) polyalkylene glycol mono (meth) acrylic acid ester type, has a poor water-reducing result, although the adsorption rate has reached 65%. It can be seen that the present invention is unique to the (poly) alkylene glycol monoalkenyl ether system described in the examples.

In Reference Example 1, it is an IR chart obtained by measuring a cement admixture in which a copolymer is an aqueous solution of 0.1% by mass using GPC. FIG. 5 is an IR chart obtained by adding a cement admixture in which a copolymer is a 0.1% by mass aqueous solution in Reference Example 1 to cement and measuring the aqueous solution after 5 minutes using GPC. FIG.

Claims (2)

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. A cement admixture comprising a copolymer comprising a structural unit derived from an ether monomer (a) and a structural unit derived from an unsaturated carboxylic acid monomer (b),
The cement admixture characterized in that the copolymer has an adsorption rate to cement particles of 40% or more. The cement admixture according to claim 1, wherein the adsorption rate is 45% or more.

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