JP5072326B2 - Method for producing polycarboxylic acid concrete admixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polycarboxylic acid-based concrete admixture with a sufficient retaining property and a stable quality while suppressing production of gel during polymerization when the polymerization is performed using a solvent containing water, in particular, when a polymer having a short chain length of a polyoxyalkylene group is manufactured. <P>SOLUTION: The manufacturing method for the polycarboxylic acid-based concrete admixture includes the polymerization step for polymerizing a monomer component in the presence of the solvent to obtain a polycarboxylic acid-based polymer. The polymerization step performs the polymerization previously using a mixture containing a water-soluble polymer containing a monomer unit having a (poly)oxyalkylene group having an average value of hydrophilic property/lipophilic property balance of less than 19 as an indispensable component and water as a solvent. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

The present invention relates to a method for producing a polycarboxylic acid concrete admixture. More specifically, the present invention relates to a method for producing a polycarboxylic acid-based concrete admixture that can be applied as a water reducing agent or the like for enhancing fluidity with respect to a cement composition or the like.

Concrete admixtures are widely used as water reducing agents for cement compositions such as cement paste, mortar and concrete, and are indispensable for building civil engineering and building structures from cement compositions. It has become. Such a concrete admixture has the effect | action which improves the intensity | strength, durability, etc. of hardened | cured material by raising the fluidity | liquidity of a cement composition and reducing a cement composition. Among these water reducing agents, polycarboxylic acid-based concrete admixtures containing polycarboxylic acid-based polymers exhibit high water-reducing performance as compared with conventional water-reducing agents such as naphthalene-based polymers, and are therefore often used as high-performance AE water-reducing agents. Have a track record.

As a method for producing such a polycarboxylic acid-based concrete admixture, a method in which water is used as a solvent and a monomer is dropped and polymerized is preferable in production, and also in a product form, water is used as a solvent. However, when the monomer to be dripped in water or the polymer to be produced is low in water solubility, if only water is used as the solvent, a large amount of gel is formed during the polymerization, and the polymerization becomes difficult. In order to improve this, there is a problem that it is necessary to remove the gel after polymerization.

As a conventional method for producing a polycarboxylic acid polymer, a polycarboxylic acid concrete admixture obtained by polymerizing a mixture containing a water-soluble polymer and water as a solvent is disclosed. (For example, refer to Patent Document 1). However, in this production method, it may be difficult to produce a polycarboxylic acid-based concrete admixture composed only of a polymer having a short chain length of a (poly) oxyalkylene group, and gelation is sufficiently suppressed. However, there was room for contrivance for producing a polymer having a short chain length of a (poly) oxyalkylene group.
JP 2004-331472 A (pages 1 to 3)

The present invention has been made in view of the above situation, and during polymerization using a solvent containing water, particularly during production of a polymer having a short chain length of a (poly) oxyalkylene group. It is an object of the present invention to provide a method for producing a polycarboxylic acid-based concrete admixture with good retention and stable quality while suppressing the formation of gel.

The inventors of the present invention have studied various methods for producing a polycarboxylic acid-based concrete admixture. By polymerizing monomer components using water as a solvent, a polycarboxylic acid-based polymer suitable as a concrete admixture. Is a method for producing a polycarboxylic acid-based concrete admixture comprising a polymerization step of polymerizing a monomer component in the presence of a solvent to obtain a polycarboxylic acid-based polymer, In the polymerization step, a water-soluble polymer having a (poly) oxyalkylene group having an average value of a hydrophilic / lipophilic balance of less than 19 and a mixture containing water and water are polymerized in advance as a solvent. If so, the formation of gel during the polymerization is sufficiently suppressed, eliminating the difficulty of polymerization and the need to remove the gel after the polymerization while maintaining good retention. Stable quality polycarboxylic acid concrete admixtures, especially polycarboxylic acid polymers obtained by polymerizing monomer components with an average hydrophilic lipophilic balance of less than 19 can be suitably produced. I found out that In the method for producing a polycarboxylic acid-based concrete admixture including a polymerization step in which a monomer component is polymerized in the presence of a solvent to obtain a polycarboxylic acid-based polymer, the polymerization step is performed by adding an average oxyalkylene group. Even when a mixture containing a water-soluble polymer having a (poly) oxyalkylene group having a mole number of less than 7 and water is polymerized as a solvent at the start of the reaction, formation of a gel during polymerization is sufficiently suppressed. However, it has good retention and stable quality, and suitably produces a polycarboxylic acid-based concrete admixture, particularly a polycarboxylic acid-based concrete admixture containing only a polymer having a short chain length of (poly) oxyalkylene groups. It was found that the effect of the present invention can be exhibited. Furthermore, when the water-soluble polymer contained in the mixture used in advance as a solvent is a polycarboxylic acid polymer, a polymer having a shorter (poly) oxyalkylene group chain length can be preferably produced. I found it. And as said polycarboxylic acid type polymer, the monomer containing the unsaturated monomer (A) which has a specific (poly) oxyalkylene group, and an unsaturated carboxylic acid type monomer (B) It has been found that it is particularly suitable if the components are obtained by a polymerization step, and the inventors have conceived that the above problems can be solved brilliantly. In addition, the polymerization step is carried out by using the average addition mole number m in the polycarboxylic acid polymer contained in the mixture used as a solvent in advance and the average addition mole number of oxyalkylene groups in the polycarboxylic acid polymer obtained by the polymerization step It has been found that when the polymerization is carried out so that m is the same, it is further advantageous in producing a polycarboxylic acid concrete admixture containing only a polymer having a short chain length of a (poly) oxyalkylene group. . Furthermore, a method for producing a polycarboxylic acid-based concrete admixture is a method for producing a polycarboxylic acid-based concrete admixture including a polymerization step in which a monomer component is polymerized in the presence of a solvent to obtain a polycarboxylic acid-based polymer. In the polymerization step, the polymerization is sufficiently suppressed by preliminarily polymerizing the polymerization initiator and / or chain transfer agent in a solvent, and the polycarboxylic acid concrete admixture, particularly ( It has been found that the effect of the present invention that a polymer having a short chain length of a poly) oxyalkylene group can be suitably produced can be achieved, and the present invention has been achieved.

That is, the present invention is a method for producing a polycarboxylic acid-based concrete admixture including a polymerization step in which a monomer component is polymerized in the presence of a solvent to obtain a polycarboxylic acid-based polymer. Polycarboxylic acid-based concrete that is polymerized using a mixture containing a water-soluble polymer essentially containing a monomer unit having a (poly) oxyalkylene group having an average lipophilic balance of less than 19 and water as a solvent. This is a method for producing an admixture.
The present invention is also a method for producing a polycarboxylic acid-based concrete admixture comprising a polymerization step in which a monomer component is polymerized in the presence of a solvent to obtain a polycarboxylic acid-based polymer, the polymerization step comprising: It is also a method for producing a polycarboxylic acid-based concrete admixture in which a mixture containing a water-soluble polymer having a (poly) oxyalkylene group having an average addition mole number of alkylene groups of less than 7 and water is used as a solvent in advance. .
The present invention further relates to a method for producing a polycarboxylic acid-based concrete admixture comprising a polymerization step in which a monomer component is polymerized in the presence of a solvent to obtain a polycarboxylic acid-based polymer, the polymerization step comprising a solvent It is also a method for producing a polycarboxylic acid-based concrete admixture in which a polymerization initiator and / or a chain transfer agent is present in advance.
The present invention is also a method for producing a polycarboxylic acid-based concrete admixture comprising a polymerization step in which a monomer component is polymerized in the presence of a solvent to obtain a polycarboxylic acid-based polymer. Before introducing the monomer into the vessel, the water-soluble polymer and / or oxy having a monomer unit having a (poly) oxyalkylene group whose average hydrophilic-lipophilic balance is less than 19 in advance in the reaction vessel. Introducing a water-soluble polymer having a (poly) oxyalkylene group having an average added mole number of an alkylene group of less than 7 and water to prepare a mixture containing the water-soluble polymer as a solvent and water; A step of adding an unsaturated monomer (A) having a (poly) oxyalkylene group to a mixture containing the water-soluble polymer obtained in the above step and water, and a water-soluble polymer obtained in the above step Not suitable for mixtures containing water It is also a method for producing a polycarboxylic acid concrete admixture and a step of adding the sum carboxylic acid monomer (B).
The present invention is described in detail below.

In the method for producing a polycarboxylic acid-based concrete admixture of the present invention, the polycarboxylic acid-based polymer is produced by producing a polycarboxylic acid-based polymer in a step of polymerizing a monomer component using a solvent containing water. Will be produced.
The method for producing a polycarboxylic acid-based concrete admixture of the present invention is as follows. (1) In the polymerization step, a (poly) oxyalkylene group having an average value of a hydrophilic-lipophilic balance (HLB) of less than 19 is used. A mixture comprising a water-soluble polymer essentially comprising a monomer unit and water, or (2) a water-soluble polymer having a (poly) oxyalkylene group in which the average number of added moles of oxyalkylene groups is less than 7 (3) Either a polymerization initiator and / or a chain transfer agent is previously present in the solvent and polymerized in advance. It includes a polymerization step in which a monomer component is polymerized in the presence of a solvent to obtain a polycarboxylic acid polymer.
As a preferable form in the manufacturing method of this invention, the combination of the form of said (1) and (2) is mentioned, for example.

One of the methods for producing the polycarboxylic acid-based concrete admixture of the present invention is a water-soluble polymer essentially comprising a monomer unit having a (poly) oxyalkylene group having an average hydrophilic-lipophilic balance of less than 19 Polymerization is performed using a mixture containing water and water as a solvent in advance.
The average value of the hydrophilic / lipophilic balance is more preferably less than 18.5.

The production method of the present invention can be suitably applied when the water solubility of the monomer used for polymerization or the polymer to be produced is low, and can effectively suppress the formation of gel during polymerization. It becomes. In such a case, the polymer contained in the mixture used in advance as a solvent sufficiently exhibits the effect of enhancing the retention. Also in this case, it is preferable to specify the degree of water solubility and hydrophobicity using the hydrophilic / lipophilic balance, and the hydrophilic / lipophilic balance of the produced polycarboxylic acid polymer is less than 19.5. It is preferable.
In the present specification, “monomer component used for polymerization” or “monomer used for polymerization” refers to a monomer component that is polymerized in the polymerization step in the production method of the present invention.

When the average hydrophilic-lipophilic balance of the monomer component used for the polymerization is less than 19.5, the conventional production method has a high possibility of forming a gel. The production method can effectively suppress the formation of gel by polymerizing the mixture in advance as a solvent. As a more preferable form, the average value of the hydrophilic / lipophilic balance of the (poly) oxyalkylene group of the monomer component used for the polymerization is 19 or less, and more preferably 18.5 or less. In the conventional production method, if the hydrophilic / lipophilic balance of the (poly) oxyalkylene group of the monomer component or the polymer to be produced is 18.5 to 19, the amount of gel becomes large and 18.5 or less. Then, there is a high possibility that polymerization will be difficult. For example, the monomer components gather in the polymerization system and cannot be uniformly polymerized, the molecular weight of the resulting polymer becomes too high to be water-soluble, and only the highly hydrophilic monomer components are polymerized in water. As a result, the copolymerization does not proceed sufficiently.

In the production method of the present invention, a mixture containing a water-soluble polymer having a monomer unit having a (poly) oxyalkylene group having an average value of a hydrophilic / lipophilic balance of less than 19 and water is used in advance as a solvent. In addition to being able to sufficiently suppress gelation, the resulting polycarboxylic acid polymer has a water-soluble polymer having a high average value of the hydrophilic-lipophilic balance (that is, hydrophilic-lipophilic balance). The water-soluble polymer having a high average value of (poly) oxyalkylene group as an essential component is not mixed, and the hydrophilic / lipophilic balance is low (for example, the hydrophilic / lipophilic balance is less than 19). It is possible to obtain a polycarboxylic acid polymer. In addition, a polycarboxylic acid polymer having a short-chain (poly) oxyalkylene group, in which a polycarboxylic acid polymer having a long-chain polyoxyalkylene group is not mixed with the obtained polycarboxylic acid-based polymer It becomes possible to get only. The method for producing such a polycarboxylic acid-based concrete admixture is novel and is one of the preferred forms of the production method of the present invention.

The production method of the present invention can also be suitably applied when the pH in the polymerization system, that is, the pH of the polymerization solution is 1.5 or more and 9 or less. More preferably, it is 8 or less. When the pH exceeds such a range, the water solubility of the polymer to be produced increases. Therefore, when the pH is high, the monomer component and the polymer to be produced have a low hydrophilic / lipophilic balance. However, there is a possibility that the gel is difficult to be formed, and there is a possibility that the production method of the present invention cannot sufficiently exhibit the effect. However, when the pH is high, the polymerization rate of the acid monomer in the monomer component may decrease.
Therefore, it is preferable to apply the present invention in a polymerization system in the above pH range so that the production method of the present invention can sufficiently exert its effect.

As the method for obtaining the hydrophilic lipophilic balance in the present invention, it is preferable to use the method for obtaining the hydrophilic lipophilic balance of Griffin. In this case, it can be obtained by the following equation.
Hydrophilic / lipophilic balance = (molecular weight of hydrophilic group) / (total molecular weight) × 100/5 = (mass% of hydrophilic group) / 5
In the hydrophilic / lipophilic balance of griffin, for example, the alkyl group is a hydrophobic group, and CH ₂ CH ₂ O is a hydrophilic group, and the molecular weight is 44. In the present invention, in the case of a propylene oxide chain (CH (CH ₃ ) CH ₂ O), a methyl group is a hydrophobic group and the rest is a hydrophilic group (not determined by the hydrophilic / lipophilic balance of griffin). .

In the water-soluble polymer used in the production method of the present invention, the hydrophilic / lipophilic balance is applied to the side chain (excluding carboxylic acid and carboxylate) of the monomer component polymerized when the water-soluble polymer is obtained. . However, the ester part (COO) and the ether part (CO) are not included.
That is, the water-soluble polymer essentially comprising a monomer unit having a (poly) oxyalkylene group having an average value of the hydrophilic-lipophilic balance of less than 19 is the hydrophilic-lipophilic balance of the side chain of the water-soluble polymer. It means that the average value of is less than 19. In the present invention, side chains formed by (poly) oxyalkylene groups are essential, but it is preferable that substantially all side chains are formed by (poly) oxyalkylene groups.
For example, it is calculated as follows.
In the case of methoxypolyethylene glycol monomethacrylate (average added mole number of ethylene oxide 10), the side chain is a part of methoxypolyethylene glycol (methoxyPEG), and the hydrophilic / lipophilic balance is as follows.
Hydrophilic lipophilic balance = (44 × 10) / (15 + 44 × 10) × 100/5 = 19.3
When the composition ratio of the monomer component is methoxypolyethylene glycol monomethacrylate (average addition mole number of ethylene oxide 2) / methoxypolyethylene glycol monomethacrylate (average addition mole number of ethylene oxide 8) (80/20 mole ratio) The oil balance is as follows.
Hydrophilic / lipophilic balance = (44 × 8 × 20 + 44 × 2 × 80) / {(15 + 44 × 8) × 20 + (15 + 44 × 2) × 80} × 100/5 = 18.1 (average chain length 3.2)
In addition, a side chain represents a monomer by X- (side chain), for example, X is C = C-COO, C = C-O, C = C-C-C, C = C-C.
It is a side chain part in the case of being represented by etc.

As the water-soluble polymer (water-soluble polymer contained in a mixture used in advance as a solvent), a polymer that does not have a polymerizable unsaturated double bond and is not taken into the polymer is preferable. For example, it is preferable to use a water-soluble polymer that is not a so-called macromonomer or the like.
The polycarboxylic acid polymer may be used in the form of a polycarboxylic acid admixture.
A water-soluble polymer having a (poly) oxyalkylene group-containing monomer unit having an average hydrophilic-lipophilic balance value of less than 19 is required to have a water-soluble polymer having an average hydrophilic-lipophilic balance value of less than 19 (poly) oxy. Although it can manufacture by copolymerizing the monomer component containing the unsaturated monomer which has an alkylene group, it is not limited to this.

In the production method of the present invention, the weight average molecular weight of the water-soluble polymer is preferably 5,000 to 100,000, more preferably 6,000 to 40,000, still more preferably 7,000 to 30,000.
Moreover, as a weight average molecular weight of the polycarboxylic acid type polymer which forms the polycarboxylic acid type concrete admixture manufactured, 50000 or less are preferable, 6000-40000 are more preferable, More preferably, it is 7000-30000.
The weight average molecular weight of the polymer is a weight average molecular weight in terms of polyethylene glycol determined by gel permeation chromatography (hereinafter referred to as “GPC”), and is preferably measured under the following GPC measurement conditions.

Column used for GPC molecular weight measurement conditions: TSKguardColumn 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

As the polycarboxylic acid polymer obtained in the polymerization step, a polymer obtained by polymerizing a monomer component essentially containing an unsaturated carboxylic acid monomer (B) described later is preferable. More preferably, the unsaturated carboxylic acid monomer (B) and the unsaturated monomer (A) having a (poly) oxyalkylene group described later are essential, and other unsaturated monomers are included as necessary. A polymer obtained by polymerizing monomer components. In this case, the composition of the monomer component forming the polycarboxylic acid polymer is preferably 20 to 70 mol% or 10 to 50 mass% for the unsaturated carboxylic acid monomer (B), 30 -60 mol% or 10-30 mass% is more preferable. Moreover, about the unsaturated monomer (A) which has a (poly) oxyalkylene group, 5-70 mol% or 50-95 mass% is preferable, and 10-60 mol% or 60-90 mass% is more preferable.

In the polymerization step, the concentration of the water-soluble polymer contained in the mixture used in advance as a solvent in the polymerization system is such that the water-soluble polymer is sufficiently soluble in order for the water-soluble polymer to fully exert its function and effect as a compatibilizer. When the total of the coalescence and water is 100% by mass, the water-soluble polymer is preferably 1% by mass to 80% by mass. More preferably, they are 3 mass% or more and 60 mass% or less, More preferably, they are 5 mass% or more and 50 mass% or less.
The amount of the water-soluble polymer used for the polycarboxylic acid polymer obtained by the polymerization step is 100% by mass of the polycarboxylic acid polymer obtained by the polymerization step. The amount is preferably 1 to 500% by mass. More preferably, it is 1-300 mass%, More preferably, it is 1-100 mass%, More preferably, it is 1-80 mass%, Most preferably, it is 1-60 mass%, Most preferably Is 1-40 mass%.
Further, the amount of the water-soluble polymer used relative to the monomer component in the polymerization step is 0.1% by mass, assuming that the amount of all monomer components used in the polymerization step is 100% by mass. % Or more, preferably 40% by mass or less. The content is more preferably 1% by mass or more, and more preferably 20% by mass or less.

The method for producing a polycarboxylic acid-based concrete admixture of the present invention comprises a polymerization step of polymerizing a monomer component in the presence of a solvent to obtain a polycarboxylic acid-based polymer. In the production method, the polymerization step is performed by polymerizing a mixture containing a water-soluble polymer having a (poly) oxyalkylene group having an average addition mole number of oxyalkylene groups of less than 7 and water in advance as a solvent. It is also a thing.

The production method of the present invention can be suitably applied when the water solubility of the monomer used for polymerization or the polymer to be produced is low, and can effectively suppress the formation of gel during polymerization. It becomes. In such a case, the polymer contained in the mixture used in advance as a solvent sufficiently exhibits the effect of enhancing the retention. In this case, it is preferable to specify the degree of water solubility and hydrophobicity using the average addition mole number of the oxyalkylene group, and the polycarboxylic acid polymer to be produced has an average addition mole number of the oxyalkylene group. It is preferable to have a (poly) oxyalkylene group with less than 7.

When the polycarboxylic acid polymer obtained by the polymerization step is a polymer having a (poly) oxyalkylene group in which the average addition mole number of oxyalkylene groups is less than 15, In such a polymerization system, the production method of the present invention can effectively suppress the formation of gel by polymerizing using the above mixture as a solvent in advance. As a more preferable form, the average value of the hydrophilic / lipophilic balance of the monomer component used for the polymerization is less than 10, more preferably 8 or less. In the conventional production method, if the average addition mole number of the oxyalkylene group in the (poly) oxyalkylene group of the monomer component or the polymer to be produced is less than 15, the gel becomes large and less than 7 Then, there is a high possibility that polymerization will be difficult. For example, the monomer components gather in the polymerization system and cannot be uniformly polymerized, the molecular weight of the resulting polymer becomes too high to be water-soluble, and only the highly hydrophilic monomer components are polymerized in water. As a result, the copolymerization does not proceed sufficiently.

In the production method of the present invention, a gel containing a water-soluble polymer having a (poly) oxyalkylene group having an average addition mole number of oxyalkylene groups of less than 7 and water is polymerized in advance as a solvent. In addition, the polycarboxylic acid polymer obtained is not mixed with a polycarboxylic acid polymer having a long-chain polyoxyalkylene group, and the average addition of oxyalkylene groups is suppressed. It becomes possible to obtain a polycarboxylic acid-based polymer having a (poly) oxyalkylene group having a small number of moles (for example, the average addition number of moles of oxyalkylene groups is less than 15). Further, the obtained polycarboxylic acid polymer does not have a (poly) oxyalkylene group having a high hydrophilic / lipophilic balance. For example, the hydrophilic / lipophilic balance is low (for example, the hydrophilic / lipophilic balance is 19. It is possible to obtain a polycarboxylic acid polymer having a (poly) oxyalkylene group (less than 5).
The average added mole number of the oxyalkylene group is more preferably less than 7, even more preferably less than 6, and particularly preferably less than 5. Moreover, it is preferable that the average addition mole number of the said oxyalkylene group is more than one.
The average addition mole number of the oxyalkylene group means an average value of the number of moles of the oxyalkylene group added in 1 mole of the group formed by the oxyalkylene group of the alkylene oxide adduct.
About preferable forms, such as a compounding ratio in the manufacturing method of this invention, it is the same as that of what was mentioned above.

A water-soluble polymer having a monomer unit having a (poly) oxyalkylene group having an average value of the hydrophilic / lipophilic balance of less than 19 or an average addition mole number of the oxyalkylene group of less than 7. A water-soluble polymer having a (poly) oxyalkylene group is also referred to as a water-soluble polymer contained in a mixture used in advance as a solvent.
Examples of the water-soluble polymer contained in the mixture previously used as a solvent include one or more polycarboxylic acid polymers.

In the method for producing a polycarboxylic acid-based concrete admixture of the present invention, the water-soluble polymer contained in the mixture used as a solvent in advance is preferably a polycarboxylic acid-based polymer.
In this specification, a polycarboxylic acid polymer contained in a mixture used as a solvent in advance in such a polymerization step is referred to as a polycarboxylic acid polymer contained in a mixture used in advance as a solvent.
In this specification, a solvent is comprised by the mixture containing a water-soluble polymer and water, and may contain the organic solvent normally used, another raw material, etc. In addition, a monomer component, a polymerization initiator, an accelerator, a chain transfer agent, a neutralizing agent (alkaline substance) used for neutralization, etc. shall not hit the solvent. In addition, the polycarboxylic acid-type polymer produced | generated during superposition | polymerization shall not hit a solvent during this superposition | polymerization. One feature of the present invention is that polymerization is performed using a mixture containing a water-soluble polymer and water as a solvent in advance. That is, a mixture containing a water-soluble polymer and water is used as a solvent for polymerization.

In the above polymerization step, the method for the presence of the water-soluble polymer and the polymerization method for “polymerizing a mixture containing a water-soluble polymer and water in advance as a solvent” are included in the mixture used in advance as a solvent. The polymer or monomer component to be polymerized may be stretched in a reaction vessel (reaction vessel) or may be dropped into the reaction vessel for polymerization. For example, (1) water and a water-soluble polymer are reacted. A monomer component is dropped into the container and polymerized, (2) Water is poured into the reaction container, and the monomer component and the water-soluble polymer are dropped into the container to polymerize, or (3 ) A method in which water, a water-soluble polymer and a monomer component are stretched and polymerized in a reaction vessel is preferable.

In the reaction vessel obtained by polymerizing the water-soluble polymer, the polymerization may be carried out by adding a new monomer component, preferably by adding a new monomer component dropwise. Further, the obtained polycarboxylic acid polymer may be polymerized so that the formation of gel is sufficiently suppressed by acting as a water-soluble polymer contained in a mixture used in advance as a solvent in the next step. Good. You may manufacture a polycarboxylic acid polymer continuously by repeating using the obtained polycarboxylic acid polymer as a water-soluble polymer contained in the mixture previously used as a solvent at the next process.
In the polymerization step in the method for producing a polycarboxylic acid-based concrete admixture of the present invention, it is preferable to add a monomer component dropwise to the solvent.

When continuously producing a polycarboxylic acid polymer, a part of the polycarboxylic acid polymer obtained in the previous step is included in the water-soluble polymer in the subsequent step (previously included in the mixture used as a solvent). Water-soluble polymer), for example, by adjusting the blending of raw materials and repeating the polymerization process, the average addition mole number m of oxyalkylene groups in the polycarboxylic acid polymer contained in the mixture used in advance as a solvent And the average added mole number m of the oxyalkylene group in the polycarboxylic acid polymer obtained by the polymerization step can be polymerized. By repeating the polymerization step, the polycarboxylic acid-based polymer contained in the mixture used as a solvent in advance and the polycarbonate obtained by the polymerization step A phosphate-based polymer makes it possible to carry out the polymerization so that the ones of the same composition. In the present invention, the effect of using the polycarboxylic acid polymer as the water-soluble polymer is exhibited, and the polycarboxylic acid polymer or single monomer having a (poly) oxyalkylene group whose average addition mole number m is adjusted to be low. A polycarboxylic acid polymer having a single composition can be prepared, which is advantageous in terms of the quality and performance of the polycarboxylic acid polymer.

In the production method of the present invention, as described above, the generation of the gel generated in the polymerization step is suppressed, but as the amount of the gel, when the total amount of the polymer obtained in the polymerization step is 100% by mass, A preferable range is 0.3 mass% or less, More preferably, it is 0.25 mass% or less.
Thereby, the quality of the polycarboxylic acid-type concrete admixture manufactured by this invention will improve more. After polymerization, the mass of the gel is determined by the gel remaining on the sieve when the polymerization reaction solution is filtered with a JIS Z8801 standard sieve (opening of 1 mm) and the gel attached to the reaction vessel, stirring blade, thermometer, etc. It can obtain | require by measuring the total mass in a water-containing state.

As the water-soluble polymer contained in the mixture used in advance as a solvent in the present invention, a polycarboxylic acid polymer is preferable.
The polycarboxylic acid polymer contained in the mixture used as a solvent in advance and the polycarboxylic acid polymer obtained by the polymerization step are the same or different, and an unsaturated monomer having a (poly) oxyalkylene group It is preferable to use a monomer component containing (A), an unsaturated carboxylic acid monomer (B), and, if necessary, another unsaturated monomer.
In the case of the polycarboxylic acid polymer contained in the mixture used as a solvent in advance, the molar ratio of the monomer component is the unsaturated monomer (A) / unsaturated having a (poly) oxyalkylene group. The molar ratio of carboxylic acid monomer (B) / other unsaturated monomer is preferably 10 to 90/10 to 90/0 to 50. More preferably, it is 20-80 / 20-80 / 0-30.
Moreover, as a polycarboxylic acid type polymer manufactured by this invention, it is preferable that the said molar ratio is 10-90 / 10-90 / 0-50. More preferably, it is 20-80 / 20-80 / 0-30.

The unsaturated monomer (A) having the (poly) oxyalkylene group may be any one having a polymerizable unsaturated group and a polyalkylene glycol chain.
In the method for producing a polycarboxylic acid-based concrete admixture according to the present invention, the polycarboxylic acid-based polymer contained in the mixture previously used as a solvent and the polycarboxylic acid-based polymer obtained by the polymerization step are the same or different. A monomer component containing an unsaturated monomer (A) having a (poly) oxyalkylene group represented by the following general formula (1) and an unsaturated carboxylic acid monomer (B): It is preferable that it is obtained by polymerization.

In General Formula (1), R ¹ and R ² are the same or different and each represents a hydrogen atom or a methyl group. R ³ represents a hydrogen atom, a methyl group, or a —X—O (R ^a O) _m —R ⁴ group. R ⁴ is the same or different and represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ^a is the same or different and represents an alkylene group having 2 to 18 carbon atoms. m is the same or different and represents the average number of added moles of the oxyalkylene group represented by R ^a O, and is a number of 1 to 300. X is the same or different and represents a divalent alkylene group having 1 to 5 carbon atoms, or when the group represented by R ¹ R ³ C═CR ² — is a vinyl group, This means that the carbon and oxygen atoms are directly bonded. X may be a —CO— bond.
If they are different, any of R ¹ , R ² , R ³ , R ⁴ , R ^a , m, X, etc. will be different.

The polymerization step in the method for producing a polycarboxylic acid-based concrete admixture of the present invention is obtained by the average addition mole number m of oxyalkylene groups in the polycarboxylic acid-based polymer contained in the mixture used in advance as a solvent, and the polymerization step. The polymerization is preferably carried out so that the average added mole number m of the oxyalkylene group in the obtained polycarboxylic acid polymer is the same.
As a property and quality of the polycarboxylic acid polymer, adjusting m is one important factor.
The average addition mole number m of the oxyalkylene group in the polycarboxylic acid polymer contained in the mixture used as a solvent in advance and the average addition mole number m of the oxyalkylene group in the polycarboxylic acid polymer obtained by the polymerization step are The same means that it can be evaluated that the performance and quality relating to m in the polycarboxylic acid polymer are the same, and it is most preferable that they are completely the same, but they may not be completely the same. The average addition mole number m of the oxyalkylene group in the polycarboxylic acid polymer contained in the mixture used as a solvent in advance and the average addition mole number m of the oxyalkylene group in the polycarboxylic acid polymer obtained by the polymerization step The difference is preferably 10 or less, more preferably 5 or less, still more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less.

The polycarboxylic acid polymer contained in the mixture used in advance as a solvent and the polycarboxylic acid polymer obtained by the polymerization step are particularly preferably a single composition polycarboxylic acid polymer. By preparing a polycarboxylic acid polymer having a single composition, other characteristics such as molecular weight become the same, which is advantageous in terms of the quality and performance of the polycarboxylic acid polymer.
That is, a method for producing a polycarboxylic acid concrete admixture containing a single composition polycarboxylic acid polymer is a preferred embodiment of the present invention.
Moreover, in the manufacturing method of the polycarboxylic acid-type concrete admixture of this invention, it is obtained by the preparation monomer composition for polymerizing and obtaining the polycarboxylic acid-type polymer contained in the mixture previously used as a solvent, and the said polymerization process. It is preferable that the charged monomer composition to be obtained by polymerizing the obtained polycarboxylic acid polymer is the same.
Charge monomer composition for obtaining a polymer obtained by polymerizing a polycarboxylic acid polymer contained in a mixture used as a solvent in advance, and a charge unit for obtaining a polymer obtained by polymerizing the polycarboxylic acid polymer obtained by the above polymerization step By making the body composition the same, it is possible to provide a continuous and stable quality without changing the polymer mixture composition.

Examples of the compound represented by the general formula (1) include unsaturated alcohol polyalkylene glycol adducts and polyalkylene glycol ester monomers.
The unsaturated alcohol polyalkylene glycol adduct may be a compound having a structure in which a polyalkylene glycol chain is added to an alcohol having an unsaturated group, and the polyalkylene glycol ester monomer may be an unsaturated compound. A monomer having a structure in which a saturated group and a polyalkylene glycol chain are bonded via an ester bond may be used, and an unsaturated carboxylic acid polyalkylene glycol ester-based compound is preferable, and among them, (alkoxy) polyalkylene Glycol mono (meth) acrylate is preferred.

When two or more oxyalkylene groups represented by-(R ^a O)-in the general formula (1) are present in the unsaturated monomer (A) having the same (poly) oxyalkylene group, The oxyalkylene group represented by — (R ^a O) — may be in any addition form such as random addition, block addition, and alternate addition.

The oxyalkylene group represented by-(R ^a O)-is an alkylene oxide adduct having 2 to 18 carbon atoms, and the structure of such an alkylene oxide adduct is ethylene oxide, propylene oxide, butylene oxide, It is a structure formed by one or more of alkylene oxides such as isobutylene oxide, 1-butene oxide and 2-butene oxide. Among such alkylene oxide adducts, ethylene oxide, propylene oxide, and butylene oxide adducts are preferable. Further, those mainly composed of ethylene oxide are more preferable.

In the polycarboxylic acid polymer to be produced, m, which is the average added mole number of the oxyalkylene group represented by R ^a O, is preferably a number of 1 to 300. When m exceeds 300, the polymerizability of the monomer is lowered. The preferable range of m is 2 or more, and the average added mole number of the oxyethylene group in — (R ^a O) _m — is preferably 2 or more. If m is less than 2 or the average added mole number of the oxyethylene group is less than 2, there is a possibility that sufficient hydrophilicity and steric hindrance to disperse cement particles may not be obtained. There is a possibility that fluidity cannot be obtained. In order to obtain excellent fluidity, the range of m is preferably 3 or more, and more preferably 280 or less. More preferably, it is 250 or less, and particularly preferably 150 or less. Moreover, as an average addition mole number of an oxyethylene group, Preferably, 2 or more is preferable and 100 or less is preferable. More preferably, it is 50 or less, More preferably, it is 20 or less, Most preferably, it is 10 or less. The average added mole number means an average value of the number of moles of the organic group added in one mole of the monomer. In order to obtain concrete with low viscosity, the range of m is preferably 1 or more, and preferably 100 or less. More preferably, it is 2 or more and 50 or less. More preferably, it is 3 or more and 30 or less. Especially preferably, it is 25 or less.
The average added mole number of the oxyethylene group means an average value of the number of moles of the oxyethylene group added in 1 mole of the group formed by the oxyalkylene group of the alkylene oxide adduct. A form in which an oxyalkylene group other than an oxyethylene group is added may be used, but a form in which only an oxyethylene group is added is preferable.

As the unsaturated monomer (A) having the (poly) oxyalkylene group, two or more types of monomers having different average added mole numbers m of oxyalkylene groups can be used in combination. As a suitable combination, for example, a combination of unsaturated monomers (A) having two types of (poly) oxyalkylene groups having a difference of m of 10 or less (preferably a difference of m of 5 or less), or each Examples thereof include combinations of unsaturated monomers (A) having three or more (poly) oxyalkylene groups having a difference in average added mole number m of 10 or less (preferably a difference of m of 5 or less).

Moreover, it is preferable that the compound represented by the said General formula (1) is a polyalkylene glycol ester-type monomer, In this case, as an oxyalkylene group represented by-(R ^<a> O) _m- , Esterification with a (meth) acrylic acid monomer is that an ethylene oxide moiety is added to an ester bond with a (meth) acrylic acid monomer (R ¹ R ³ C═CR ² —COOH). This is preferable from the viewpoint of improving productivity.

When R ⁴ has more than 20 carbon atoms, the cement composition may not be able to obtain good dispersibility. A preferred form of R ⁴ is a hydrocarbon group having 1 to 20 carbon atoms or hydrogen from the viewpoint of dispersibility. More preferably, it is a hydrocarbon group having 10 or less carbon atoms, more preferably 3 or less carbon atoms, and particularly preferably 2 or less carbon atoms. Of the hydrocarbon groups, a saturated alkyl group and an unsaturated alkyl group are preferable. These alkyl groups may be linear or branched. In addition, in order to achieve excellent material separation prevention performance and an appropriate amount of air entrained in the cement composition, it is preferably a hydrocarbon group having 5 or more carbon atoms, A hydrocarbon group of 20 or less is preferable. More preferably, it is a C5-C10 hydrocarbon group. Of the hydrocarbon groups, a saturated alkyl group and an unsaturated alkyl group are preferable. These alkyl groups may be linear or branched.

Examples of the unsaturated alcohol polyalkylene glycol adduct include vinyl alcohol alkylene oxide adduct, (meth) allyl alcohol alkylene oxide adduct, 3-buten-1-ol alkylene oxide adduct, isoprene alcohol (3-methyl- 3-buten-1-ol) alkylene oxide adduct, 3-methyl-2-buten-1-ol alkylene oxide adduct, 2-methyl-3-buten-2-ol alkylene oxide adduct, 2-methyl-2 -Butene-1-ol alkylene oxide adducts and 2-methyl-3-buten-1-ol alkylene oxide adducts are preferred.

Examples of the (alkoxy) polyalkylene glycol mono (meth) acrylate include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, and 3-pen. C1-C30 aliphatic alcohols such as butanol, 1-hexanol, 2-hexanol, 3-hexanol, octanol, 2-ethyl-1-hexanol, nonyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol, cyclohexanol C3-C30 unsaturated alcohols such as C3-C30 alicyclic alcohols such as (meth) allyl alcohol, 3-buten-1-ol, 3-methyl-3-buten-1-ol In any of the above classes, Alkoxy polyalkylene glycols in which the Sid group and 1 to 300 mols, particularly the alkoxy polyalkylene glycol is ethylene oxide mainly is suitable ester of (meth) acrylic acid.

As the esterified product, the following (alkoxy) polyethylene glycol (poly) (C2-C4 alkylene glycol) (meth) acrylic acid esters and the like are preferable.
Methoxy polyethylene glycol mono (meth) acrylate, methoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate.

Butoxy polyethylene glycol mono (meth) acrylate, butoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate.

Heptoxy polyethylene glycol mono (meth) acrylate, heptoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate, heptoxy {polyethylene glycol (poly) butylene glycol} mono (meth) acrylate, heptoxy {polyethylene glycol (poly) propylene Glycol (poly) butylene glycol} mono (meth) acrylate, octoxypolyethylene glycol mono (meth) acrylate, octoxy {polyethyleneglycol (poly) propyleneglycol} mono (meth) acrylate, octoxy {polyethyleneglycol (poly) butyleneglycol} mono (Meth) acrylate, octoxy {polyethylene glycol (poly) propylene glycol (poly) butylene Recall} mono (meth) acrylate, nonanoxy polyethylene glycol mono (meth) acrylate, nonanoxy {polyethylene glycol (poly) propylene glycol} mono (meth) acrylate, nonanoxy {polyethylene glycol (poly) butylene glycol} mono (meth) acrylate, Nonanoxy {polyethylene glycol (poly) propylene glycol (poly) butylene glycol} mono (meth) acrylate is preferred.

As the unsaturated monomer (A) having the (poly) oxyalkylene group, in addition to (alkoxy) polyalkylene glycol mono (meth) acrylate, (alkoxy) polyalkylene glycol monomaleic acid ester, (alkoxy) Polyalkylene glycol dimaleic acid esters are preferred.

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 ⁵ represents a hydrogen atom or a methyl group. R ⁶ and R ^{7 each} represent a hydrogen atom, a methyl group, or —COOM. M represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group (protonated organic amine).
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, etc .; these monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts (organic ammonium salts) are suitable. It is. 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 dispersibility, and 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, citraconic acid, fumaric acid Etc., their monovalent metal salts, divalent metal salts, ammonium salts and organic amine salts, or their anhydrides are preferred.
In addition to these, the unsaturated dicarboxylic acid monomer is a half ester of an unsaturated dicarboxylic acid monomer and an alcohol having 1 to 22 carbon atoms, an unsaturated dicarboxylic acid, and 1 to 22 carbon atoms. A half amide of the above amine, a half ester of an unsaturated dicarboxylic acid monomer and a glycol having 2 to 4 carbon atoms, and a half amide of maleamic acid and a glycol having 2 to 4 carbon atoms are preferable.

As the other unsaturated monomer, for example, a (meth) acrylic acid ester monomer or an ethylene monomer having a multi-branched (poly) oxyalkylene group is preferable. As said (meth) acrylic acid ester-type monomer, the alkyl (meth) acrylate which has a C1-C10 alkyl group is suitable, for example. Among these, alkyl (meth) acrylates having an alkyl group having 1 to 4 carbon atoms are preferable, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid. And propyl. More preferred is methyl (meth) acrylate.

In the alkylene oxide adduct, the average addition mole number of the oxyalkylene group is preferably 1 or more and 300 or less. More preferably, it is 0.5 or more, more preferably 1, or more, particularly preferably 2, or more, most preferably 3, or more. More preferably, it is 200 or less, More preferably, it is 150 or less, Especially preferably, it is 100 or less, Most preferably, it is 50 or less. If the average addition mole number of the oxyalkylene group in the alkylene oxide adduct is outside such a range, the polymer to be produced may not be sufficiently hydrophobic.

The method for producing a polycarboxylic acid-based concrete admixture according to the present invention also includes a polymerization step of polymerizing a monomer component in the presence of a solvent to obtain a polycarboxylic acid-based polymer. In this method, i) a (poly) oxyalkylene group having an average hydrophilic-lipophilic balance of less than 19 is previously introduced into the reaction vessel before introducing the monomer into the reaction vessel (reaction vessel). As a solvent, a water-soluble polymer having an essential monomer unit and / or a water-soluble polymer having a (poly) oxyalkylene group having an average addition mole number of oxyalkylene groups of less than 7 and water are introduced. A step of preparing a mixture containing the water-soluble polymer of (ii) and water, and ii) an unsaturated monomer having a (poly) oxyalkylene group in the mixture containing the water-soluble polymer obtained in step i) and water. Add (A) And iii) a step of adding an unsaturated carboxylic acid monomer (B) to a mixture containing the water-soluble polymer obtained in step i) and water. It is also a manufacturing method.
By using such a production method, it is possible to suppress the formation of a gel during the polymerization, particularly when the water content of the monomer component or the polymer is low, when polymerizing using a solvent containing water. Thus, a polycarboxylic acid concrete admixture suitable as a water reducing agent for cement compositions such as cement paste, mortar and concrete can be easily produced.
The manufacturing method of the said polycarboxylic acid-type concrete admixture and the preferable form mentioned above can be combined suitably, and can be used.
The step ii) and the step iii) may be performed simultaneously or separately. When performed separately, the step iii) may be performed after the step ii), or the step ii) may be performed after the step iii). Among them, it is preferable to perform the step ii) and the step iii) at the same time, for example, a form in which a mixed solution containing a monomer having a (poly) oxyalkylene group and an unsaturated carboxylic acid monomer is dropped. preferable.

The method for producing a polycarboxylic acid-based concrete admixture according to the present invention also includes a polymerization step of polymerizing a monomer component in the presence of a solvent to obtain a polycarboxylic acid-based polymer. It is a method, Comprising: The said superposition | polymerization process is also a manufacturing method of the polycarboxylic-acid-type concrete admixture which superposes | polymerizes by making a polymerization initiator and / or a chain transfer agent exist beforehand in a solvent.

The production method of the present invention can be suitably applied when the water solubility of the monomer used for polymerization or the polymer to be produced is low, and can effectively suppress the formation of gel during polymerization. It becomes. In such a case, the polymerization initiator and / or chain transfer agent present in the solvent sufficiently exhibits the effect of enhancing the retention.

In the conventional production method, there is a high possibility that a gel is formed, and in such a polymerization system, the production method of the present invention polymerizes in the presence of the polymerization initiator and / or chain transfer agent in a solvent in advance. Thereby, the production | generation of a gel can be suppressed effectively. In the conventional production method, when the average addition mole number of the oxyalkylene group in the (poly) oxyalkylene group of the monomer component or the polymer to be produced is less than 15, the gel becomes large and less than 10. Then, there is a high possibility that polymerization will be difficult. For example, the monomer components gather in the polymerization system and cannot be uniformly polymerized, the molecular weight of the resulting polymer becomes too high to be water-soluble, and only the highly hydrophilic monomer components are polymerized in water. As a result, the copolymerization does not proceed sufficiently.

In the production method of the present invention, the polymerization can be sufficiently suppressed by polymerizing the polymerization initiator and / or chain transfer agent in the solvent in advance, and the resulting polycarboxylic acid heavy polymer is obtained. The coalescence does not have a high average value of the hydrophilic / lipophilic balance, for example, a polycarboxylic acid system essentially comprising a monomer unit having a (poly) oxyalkylene group whose average value of the hydrophilic / lipophilic balance is less than 15 Only a polymer can be obtained. In addition, for example, a polycarboxylic acid-based polymer having a short-chain (poly) oxyalkylene group in which a polycarboxylic acid-based polymer having a long-chain polyoxyalkylene group is not mixed with the obtained polycarboxylic acid-based polymer. Only a polymer can be obtained.
When the polycarboxylic acid polymer has a (poly) oxyalkylene group, the average added mole number of the oxyalkylene group in the (poly) oxyalkylene group is more preferably 8 or less, still more preferably 5 or less.
About preferable forms, such as the compounding ratio of the polycarboxylic acid type polymer obtained by the said polymerization process in the manufacturing method of this invention, and a monomer component, it is the same as that of the preferable form mentioned above.

Examples of the polymerization initiator include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate; hydrogen peroxide; azo compounds such as azobis-2methylpropionamidine hydrochloride and azoisobutyronitrile; Peroxides such as oxide, lauroyl peroxide and cumene hydroperoxide are preferred. 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 amount of the polymerization initiator previously present in the solvent is, for example, preferably 0.001% by mass or more and preferably 5% by mass or less with respect to 100% by mass of the monomer component. The content is more preferably 0.01% by mass or more, and more preferably 1% by mass or less.
The total amount of the polymerization initiator used (the total amount of the polymerization initiator added in advance after the start of the reaction of the polymerization initiator and the monomer component previously present in the solvent) is, for example, 0 with respect to 100% by mass of the monomer component. 0.05 mass% or more is preferable, and 5 mass% or less is preferable. The content is more preferably 0.1% by mass or more, and more preferably 1% by mass or less.
The amount of the accelerator previously present in the solvent is, for example, preferably 0.001% by mass or more and preferably 5% by mass or less with respect to 100% by mass of the monomer component. The content is more preferably 0.01% by mass or more, and more preferably 1% by mass or less.
The total amount of the accelerator used (the total amount of the accelerator previously present in the solvent and the accelerator added after the start of the reaction of the monomer component) is, for example, 0.05 mass with respect to 100 mass% of the monomer component. % Or more, preferably 5% by mass or less. The content is more preferably 0.1% by mass or more, and more preferably 1% by mass or less.
The accelerator may be preliminarily present in the solvent, or may be added after the reaction of the monomer component (for example, dropwise at the same time as the monomer component).

In the polymerization, a chain transfer agent is preferably used for stable molecular weight control. One or more chain transfer agents may be used as necessary from the viewpoint of compatibility with monomers and solubility in a solvent. I can do it. As such a chain transfer agent, a thiol compound having a hydrocarbon group having 3 or more carbon atoms or a compound having a solubility in water at 25 ° C. of 10% or less is preferable. The chain transfer agent, butanethiol, octane described above Thiol, decanethiol, dodecanethiol, thiophenol, octyl thioglycolate, octyl 2-mercaptopropionate, octyl 3-mercaptopropionate, dodecyl mercaptan, mercaptoethanol, thioglycerol, thioglycolic acid, mercaptopropionic acid, 2-mercapto Thiol chain transfer agents such as propionic acid, 3-mercaptopropionic acid, thiomalic acid and 2-mercaptoethanesulfonic acid; secondary alcohols such as isopropanol; phosphorous acid, hypophosphorous acid and salts thereof (sodium hypophosphite) , Hya Etc. potassium) and sulfite are preferred.
The amount of the chain transfer agent previously present in the solvent is 100% by mass with respect to 100% by mass of the chain transfer agent added after the reaction of the monomer component starts (for example, the amount of the chain transfer agent dripped simultaneously with the monomer). , 0.1% by mass or more, preferably 40% by mass or less. The content is more preferably 1% by mass or more, and more preferably 20% by mass or less.
The total amount of the chain transfer agent used (the total amount of the chain transfer agent previously present in the solvent and the chain transfer agent added after the start of the reaction of the monomer component) is 0% with respect to 100% by mass of the monomer component. It is preferably 1% by mass or more, and preferably 10% by mass or less. The content is more preferably 0.5% by mass or more, and more preferably 5% by mass or less.

As a method for adding the polymerization initiator and / or chain transfer agent to the reaction vessel, a continuous charging method such as dropping or divided charging can be applied. In addition, a polymerization initiator and / or a chain transfer agent may be introduced into the reaction vessel alone, and are previously confused with an unsaturated monomer having an oxyalkylene group constituting the monomer component, a solvent, or the like. May be.
Among them, it is preferable to add a polymerization initiator and / or a chain transfer agent dropwise to the solvent. For example, the polymerization initiator and / or the chain transfer agent is dropped first, and then the polymerization initiator together with the monomer component. And the method of dripping a chain transfer agent is a suitable mode. For example, it is preferable to start dropping the polymerization initiator and / or chain transfer agent in advance of 10 minutes to 45 minutes.
At this time, the amount of the polymerization initiator and / or chain transfer agent dripped in advance becomes the amount of the polymerization initiator and / or chain transfer agent previously present in the solvent, and the polymerization start dripped together with the monomer component. The amount of the agent and / or chain transfer agent is the amount of the polymerization initiator and / or chain transfer agent added after the start of the reaction of the monomer component.
In the polymerization step in the method for producing the polycarboxylic acid-based concrete admixture of the present invention, the above-described polymerization initiator, accelerator and chain transfer agent can be appropriately used.

Hereinafter, the polymerization method, cement additive and the like will be further described.
The polymerization method can be carried out either batchwise or continuously.
In the above polymerization method, the polymerization conditions such as the polymerization temperature are appropriately determined depending on the polymerization method used, the solvent, the polymerization initiator, and the chain transfer agent, but the polymerization temperature is usually preferably 0 ° 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 50 degreeC or more, Most preferably, it is 60 degreeC or more. More preferably, it is 120 degrees C or less, More preferably, it is 100 degrees C or less, Most preferably, it is 85 degrees C or less.

The polycarboxylic acid polymer produced by the above polymerization method is used as it is as a main component of the polycarboxylic acid concrete admixture, 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 polycarboxylic acid-based concrete admixture produced by the production method of the present invention means an agent that can be mixed with a cement composition or the like, that is, an agent comprising a cement additive or the like. The polycarboxylic acid polymer obtained by the polymerization step of the present invention is suitable as a main component of the cement additive, and can thereby constitute the polycarboxylic acid concrete admixture. Such cement additives are described below.

The cement additive can be used in addition to a cement composition such as cement paste, mortar, and concrete. It can also be used for ultra high strength concrete. As the cement composition, those usually used including cement, water, fine aggregate, coarse aggregate and the like are suitable. Moreover, what added fine powders, such as a fly ash, blast furnace slag, a silica fume, and a limestone, may be used. Ultra-high-strength concrete is generally called as such in the field of cement composition, that is, the cured product is equivalent to the conventional one even if the water / cement ratio is smaller than that of conventional concrete. Or concrete having a higher strength, for example, the water / cement ratio is 25% by mass or less, further 20% by mass or less, particularly 18% by mass or less, particularly 14% by mass or less, especially about 12% by mass. However, it becomes a concrete having workability that does not hinder normal use, and the cured product thereof is 60 N / mm ² or more, further 80 N / mm ² or more, further 100 N / mm ² or more, particularly 120 N / mm ² or more. , in particular 160 N / mm ² or more, and particularly will exhibit 200 N / mm ² or more compression strength.

As the cement, portland cement such as normal, early strength, super early strength, moderate heat, white, etc .; mixed portland cement such as alumina cement, fly ash cement, blast furnace cement, silica cement and the like are suitable. As the blending amount and unit water amount per 1 m ³ of concrete of the cement, for example, in order to produce highly durable and high strength concrete, the unit water amount is 100 to 185 kg / m ³ , and the water / cement ratio is 10 to 70. % Is preferable. More preferably, the unit water amount is 120 to 175 kg / m ³ and the water / cement ratio is 20 to 65%.

The amount of the cement additive added to the cement composition is such that the polycarboxylic acid polymer produced by the polymerization process of the present invention is 0.01% by mass or more with respect to 100% by mass of the total mass of the cement. It is preferable to be such that it is 10% by mass or less. If it is less than 0.01% by mass, the cement composition may not be sufficient in terms of performance, and if it exceeds 10% by mass, the economy may be inferior. More preferably, it is 0.05 mass% or more, and is 8 mass% or less, More preferably, it is 0.1 mass% or more, and is 5 mass% or less. In addition, the said mass% is a value of solid content conversion.

The cement additive can be used in combination with a commonly used cement dispersant. As the cement dispersant, the following are suitable.
Lignin sulfonate; polyol derivative; naphthalene sulfonic acid formalin condensate; melamine sulfonic acid formalin condensate.

When the cement dispersant is used in combination, it is not uniquely determined depending on the type of cement dispersant to be used, blending, test conditions, etc., but the proportion of the blending mass of the cement additive and the cement dispersant Is preferably 5 to 95:95 to 5. More preferably, it is 10-90: 90-10.

Moreover, the said cement additive can also be used in combination with another cement additive. Examples of the other cement additives include cement additives (materials) as shown below.
(1) Water-soluble polymer substance: unsaturated carboxylic acid polymer such as polyacrylic acid (sodium), polymethacrylic acid (sodium), polymaleic acid (sodium); nonionic cellulose ether such as methylcellulose, ethylcellulose, hydroxymethylcellulose Polysaccharides; polyvinyl alcohol; starch and the like.

(2) Polymer emulsion: Copolymers of various vinyl monomers such as alkyl (meth) acrylate.
(3) retarder: gluconic acid, glucoheptonic acid, malic acid or citric acid, and oxycarboxylic acids such as inorganic salts or organic salts such as sodium, potassium and calcium and salts thereof; glucose, fructose, galactose, saccharose Monosaccharides such as disaccharides, oligosaccharides such as disaccharides and trisaccharides, oligosaccharides such as dextrins, polysaccharides such as dextran, and sugars such as molasses containing these.

(4) Early strengthening agent / accelerator: Calcium salts such as calcium chloride, calcium nitrite, calcium nitrate.
(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 higher alcohols having 12 to 14 carbon atoms such as oxyethyleneoxypropylene adducts; (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 -Bu Acetylene ethers obtained by addition polymerization of alkylene oxide to acetylene alcohol such as n-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 esters; (poly) oxyethylene stearyl phosphates, etc. Polyoxyalkylene alkyl phosphoric acid esters; polyoxyethylene such as polyoxyethylene lauryl amine (poly) oxyalkylene alkyl amines; polyoxyalkylene amide.

(10) In addition, alcohol-based antifoaming agents; amide-based antifoaming agents; phosphate ester-based antifoaming agents; silicone-based antifoaming agents and the like.

Since the method for producing the polycarboxylic acid-based concrete admixture of the present invention has the above-described configuration, this makes it particularly effective when the monomer component or the polymer is water-soluble when polymerized using a solvent containing water. It is possible to easily produce a polycarboxylic acid-based concrete admixture suitable as a water reducing agent for cement compositions such as cement paste, mortar, and concrete by suppressing the formation of gel during polymerization when low. It will be possible.

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. Note that “%” means “mass%” unless otherwise specified.

Comparative Example 1
A glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introducing tube, and a reflux condenser (condenser) was charged with 1026.3 g of water, and the reactor was stirred under nitrogen. The temperature was raised to 70 ° C. in a nitrogen atmosphere. Next, 1100.8 g of methoxypolyethylene glycol monomethacrylate (average number of added moles of ethylene oxide 4), 200.7 g of methacrylic acid, 67.7 g of sodium methacrylate, 15.4 g of 3-mercaptopropionic acid and 233 ion-exchanged water were added to the reactor. .4 g of the mixed solution was added dropwise over 6 hours, and at the same time, an aqueous solution in which 18.9 g of 30% hydrogen peroxide was dissolved in 71.6 g of water and 7.3 g of L-ascorbic acid were dissolved in 74.2 g of water. The aqueous solution was added dropwise over 7 hours.
After completion of dropping, the reaction mixture was maintained at 70 ° C. for 1 hour. Furthermore, by adjusting the pH of the reaction mixture to 7 with sodium hydroxide, the polycarboxylic acid (1) (monomer) in the present invention having a weight average molecular weight of 23600 in terms of polyethylene glycol by gel permeation chromatography An average value of 18.4) of the hydrophilic / lipophilic balance of the components was obtained.
When the mass of the gel adhering to the polymerization reaction solution and to the reaction solution, stirring blade, thermometer and the like after polymerization was confirmed, a gel of 3.2 g / 1000 g aqueous polymer solution was observed.
The mass of the gel is the gel concentration in the water-containing state of the gel remaining on the filter when the polymerization reaction solution is filtered through a 100 mesh metal filter after polymerization and the gel adhering to the reaction vessel, stirring blade, thermometer, etc. is there.
The solid content of the obtained polymer aqueous solution was 49.4%.

Example 1
48 obtained by polymerizing 1025.6 g of water and Comparative Example 1 in a glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube, and reflux condenser (condenser). 143.9 g of a% polymer aqueous solution was charged, the reactor was purged with nitrogen under stirring, and the temperature was raised to 70 ° C. under a nitrogen atmosphere. Next, 1100.8 g of methoxypolyethylene glycol monomethacrylate (average number of added moles of ethylene oxide 4), 200.7 g of methacrylic acid, 67.7 g of sodium methacrylate, 15.4 g of 3-mercaptopropionic acid and ion-exchanged water were added to the reactor. 233.4 g of the mixed solution was dropped over 6 hours, and at the same time, an aqueous solution in which 18.9 g of 30% hydrogen peroxide was dissolved in 71.6 g of water and 7.3 g of L-ascorbic acid were dissolved in 74.2 g of water. The aqueous solution was added dropwise over 7 hours.
After completion of dropping, the reaction mixture was maintained at 70 ° C. for 1 hour. Furthermore, the polycarboxylic acid (2) in the present invention having a weight average molecular weight of 24,000 in terms of polyethylene glycol by gel permeation chromatography was obtained by adjusting the pH of the reaction mixture to 7 with sodium hydroxide.
When the mass of the gel adhering to the polymerization reaction solution and to the reaction solution, stirring blade, thermometer and the like after polymerization was confirmed, a gel of 0.4 g / 1000 g aqueous polymer solution was observed.
The mass of the gel is the gel concentration in the water-containing state of the gel remaining on the filter when the polymerization reaction solution is filtered through a 100 mesh metal filter after polymerization and the gel adhering to the reaction vessel, stirring blade, thermometer, etc. is there.
The solid content of the obtained polymer aqueous solution was 49.4%.

Example 2
48 obtained by polymerizing 1025.6 g of water and Comparative Example 1 in a glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube, and reflux condenser (condenser). A 57% aqueous polymer solution was charged, the reactor was purged with nitrogen under stirring, and the temperature was raised to 70 ° C. under a nitrogen atmosphere. Next, 1100.8 g of methoxypolyethylene glycol monomethacrylate (average number of added moles of ethylene oxide 4), 200.7 g of methacrylic acid, 67.7 g of sodium methacrylate, 15.4 g of 3-mercaptopropionic acid and 233 ion-exchanged water were added to the reactor. .4 g of the mixed solution was added dropwise over 6 hours, and at the same time, an aqueous solution in which 18.9 g of 30% hydrogen peroxide was dissolved in 71.6 g of water and 7.3 g of L-ascorbic acid were dissolved in 74.2 g of water. The aqueous solution was added dropwise over 7 hours.
After completion of dropping, the reaction mixture was maintained at 70 ° C. for 1 hour. Furthermore, the polycarboxylic acid (3) in the present invention having a weight average molecular weight of 21,900 in terms of polyethylene glycol by gel permeation chromatography was obtained by adjusting the pH of the reaction mixture to 7 with sodium hydroxide.
When the mass of the gel adhering to the polymerization reaction solution and to the reaction solution, stirring blade, thermometer and the like after polymerization was confirmed, a gel of 1.0 g / 1000 g aqueous polymer solution was observed.
The mass of the gel is the gel concentration in the water-containing state of the gel remaining on the filter when the polymerization reaction solution is filtered through a 100 mesh metal filter after polymerization and the gel adhering to the reaction vessel, stirring blade, thermometer, etc. is there.
The solid content of the obtained polymer aqueous solution was 49.4%.

Example 3
A glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introducing tube, and a reflux condenser (condenser) was charged with 1026.3 g of water, and the reactor was stirred under nitrogen. The temperature was raised to 70 ° C. in a nitrogen atmosphere. Next, an aqueous solution in which 18.9 g of 30% hydrogen peroxide was dissolved in 71.6 g of water and an aqueous solution in which 7.3 g of L-ascorbic acid was dissolved in 74.2 g of water were added to the reactor over 7 hours and 15 minutes. And dripped. 15 minutes after the start of dropping of the aqueous hydrogen peroxide solution and the aqueous L-ascorbic acid solution, 1100.8 g of methoxypolyethylene glycol monomethacrylate (average added mole number of ethylene oxide 4), 200.7 g of methacrylic acid, 67.7 g of sodium methacrylate, 3- A mixed solution of 15.4 g of mercaptopropionic acid and 233.4 g of ion-exchanged water was added dropwise over 6 hours.
After completion of dropping, the reaction mixture was maintained at 70 ° C. for 1 hour. Furthermore, the polycarboxylic acid (4) in the present invention having a weight average molecular weight of 22400 in terms of polyethylene glycol by gel permeation chromatography was obtained by adjusting the pH of the reaction mixture to 7 with sodium hydroxide.
When the mass of the gel adhering to the polymerization reaction solution and to the reaction solution, stirring blade, thermometer and the like after polymerization was confirmed, a 1.6 g / 1000 g aqueous polymer gel was observed.
The mass of the gel is the gel concentration in the water-containing state of the gel remaining on the filter when the polymerization reaction solution is filtered through a 100 mesh metal filter after polymerization and the gel adhering to the reaction vessel, stirring blade, thermometer, etc. is there.
The solid content of the obtained polymer aqueous solution was 49.4%.

Example 4
A glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introducing tube, and a reflux condenser (condenser) was charged with 1026.3 g of water, and the reactor was stirred under nitrogen. The temperature was raised to 70 ° C. in a nitrogen atmosphere. Next, an aqueous solution in which 18.9 g of 30% hydrogen peroxide was dissolved in 71.6 g of water and an aqueous solution in which 7.3 g of L-ascorbic acid was dissolved in 74.2 g of water were added to the reactor over 7 hours and 30 minutes. And dripped. 30 minutes after the start of dropping of the hydrogen peroxide aqueous solution and the L-ascorbic acid aqueous solution, 1100.8 g of methoxypolyethylene glycol monomethacrylate (average added mole number of ethylene oxide 4), 200.7 g of methacrylic acid, 67.7 g of sodium methacrylate, 3- A mixed solution of 15.4 g of mercaptopropionic acid and 233.4 g of ion-exchanged water was added dropwise over 6 hours.
After completion of dropping, the reaction mixture was maintained at 70 ° C. for 1 hour. Furthermore, the polycarboxylic acid (5) in the present invention having a weight average molecular weight of 22400 in terms of polyethylene glycol by gel permeation chromatography was obtained by adjusting the pH of the reaction mixture to 7 with sodium hydroxide.
When the mass of the gel adhering to the polymerization reaction solution and to the reaction solution, stirring blade, thermometer and the like after polymerization was confirmed, a 1.6 g / 1000 g aqueous polymer gel was observed.
The mass of the gel is the gel concentration in the water-containing state of the gel remaining on the filter when the polymerization reaction solution is filtered through a 100 mesh metal filter after polymerization and the gel adhering to the reaction vessel, stirring blade, thermometer, etc. is there.
The solid content of the obtained polymer aqueous solution was 49.4%.

Example 5
A glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube, and reflux condenser (condenser) was charged with 1025.6 g of water and 0.309 g of 3-mercaptopropionic acid. The reactor was replaced with nitrogen under stirring, and the temperature was raised to 70 ° C. under a nitrogen atmosphere. Next, 1100.8 g of methoxypolyethylene glycol monomethacrylate (average number of added moles of ethylene oxide 4), 200.7 g of methacrylic acid, 67.7 g of sodium methacrylate, 15.4 g of 3-mercaptopropionic acid and ion-exchanged water were added to the reactor. 233.4 g of the mixed solution was dropped over 6 hours, and at the same time, an aqueous solution in which 18.9 g of 30% hydrogen peroxide was dissolved in 71.6 g of water and 7.3 g of L-ascorbic acid were dissolved in 74.2 g of water. The aqueous solution was added dropwise over 7 hours.
After completion of dropping, the reaction mixture was maintained at 70 ° C. for 1 hour. Furthermore, by adjusting the pH of the reaction mixture to 7 with sodium hydroxide, polycarboxylic acid (6) according to the present invention having a weight average molecular weight of 21,000 in terms of polyethylene glycol by gel permeation chromatography was obtained.
When the mass of the gel adhering to the polymerization reaction solution and to the reaction solution, stirring blade, thermometer and the like after polymerization was confirmed, a gel of 1.5 g / 1000 g aqueous polymer solution was observed.
The mass of the gel is the gel concentration in the water-containing state of the gel remaining on the filter when the polymerization reaction solution is filtered through a 100 mesh metal filter after polymerization and the gel adhering to the reaction vessel, stirring blade, thermometer, etc. is there.
The solid content of the obtained polymer aqueous solution was 49.4%.

Example 6
A glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introducing tube, and a reflux condenser (condenser) was charged with 1025.6 g of water and 0.773 g of 3-mercaptopropionic acid. The reactor was purged with nitrogen under stirring, and the temperature was raised to 70 ° C. under a nitrogen atmosphere. Next, 1100.8 g of methoxypolyethylene glycol monomethacrylate (average number of added moles of ethylene oxide 4), 200.7 g of methacrylic acid, 67.7 g of sodium methacrylate, 15.4 g of 3-mercaptopropionic acid and ion-exchanged water were added to the reactor. 233.4 g of the mixed solution was dropped over 6 hours, and at the same time, an aqueous solution in which 18.9 g of 30% hydrogen peroxide was dissolved in 71.6 g of water and 7.3 g of L-ascorbic acid were dissolved in 74.2 g of water. The aqueous solution was added dropwise over 7 hours.
After completion of dropping, the reaction mixture was maintained at 70 ° C. for 1 hour. Furthermore, the polycarboxylic acid (7) in the present invention having a weight average molecular weight of 22300 in terms of polyethylene glycol by gel permeation chromatography was obtained by adjusting the pH of the reaction mixture to 7 with sodium hydroxide.
When the mass of the gel adhering to the polymerization reaction solution and to the reaction solution, stirring blade, thermometer and the like after polymerization was confirmed, a gel of 1.8 g / 1000 g polymer aqueous solution was observed.
The mass of the gel is the gel concentration in the water-containing state of the gel remaining on the filter when the polymerization reaction solution is filtered through a 100 mesh metal filter after polymerization and the gel adhering to the reaction vessel, stirring blade, thermometer, etc. is there.
The solid content of the obtained polymer aqueous solution was 49.4%.

In Table 1, MPA in the monomer represents 3-mercaptopropionic acid added together with the monomer component.
Production Example 1
A glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introduction tube, and a reflux condenser (condenser) was charged with 460.0 g of water, and the reactor was nitrogenated under stirring. The temperature was raised to 80 ° C. in a nitrogen atmosphere. Next, 533.4 g of methoxypolyethylene glycol monomethacrylate (average number of added moles of ethylene oxide 10), 120.6 g of methacrylic acid, 27.0 g of sodium methacrylate, 8.5 g of 3-mercaptopropionic acid and ion-exchanged water were added to the reactor. At the same time, 201.3 g of the mixed solution was dropped over 4 hours, and at the same time, an aqueous solution in which 6.44 g of ammonium persulfate was dissolved in 110.1 g of water was dropped over 5 hours.
After completion of dropping, the reaction mixture was maintained at 80 ° C. for 1 hour. Furthermore, by adjusting the pH of the reaction mixture to 7 with sodium hydroxide, a polycarboxylic acid (8) (single chain length 10 mol) having a weight average molecular weight of 17,000 in terms of polyethylene glycol by gel permeation chromatography. An average value of 19.3) of the hydrophilic / lipophilic balance of the monomer component was obtained.
The obtained polymer aqueous solution had a solid content of 46.1%.

Production Example 2
A glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introduction tube, and a reflux condenser (condenser) was charged with 525.7 g of water, and the reactor was nitrogenated under stirring. The temperature was raised to 80 ° C. in a nitrogen atmosphere. Next, 535.7 g of methoxypolyalkylene glycol monomethacrylate (added 10 mol of ethylene oxide, 2 mol of propylene oxide, and 13 mol of ethylene oxide from the methoxy group side) from the methoxy group side, 118.8 g of methacrylic acid, sodium methacrylate A mixed solution of 25.9 g, 13.51 g of 3-mercaptopropionic acid and 81.2 g of ion-exchanged water was added dropwise over 4 hours, and at the same time, an aqueous solution in which 7.76 g of ammonium persulfate was dissolved in 72.2 g of water was taken over 5 hours. And dripped.
After completion of dropping, the reaction mixture was maintained at 80 ° C. for 1 hour. Furthermore, by adjusting the pH of this reaction mixture to 7 with sodium hydroxide, a polycarboxylic acid (9) having a weight average molecular weight of 15000 in terms of polyethylene glycol by gel permeation chromatography (the hydrophilicity of the monomer component) An average value of 19.2) of the lipophilic balance was obtained.
The obtained polymer aqueous solution had a solid content of 46.1%.

Comparative Example 2
46 obtained by polymerizing 1025.6 g of water and Preparation Example 1 in a glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, stirrer, dropping funnel, nitrogen introducing tube, and reflux condenser (condenser) 201.5 g of a 1% polymer aqueous solution was charged, and the reactor was purged with nitrogen under stirring, and the temperature was raised to 70 ° C. in a nitrogen atmosphere. Next, 1100.8 g of methoxypolyethylene glycol monomethacrylate (average number of added moles of ethylene oxide 4), 200.7 g of methacrylic acid, 67.7 g of sodium methacrylate, 15.4 g of 3-mercaptopropionic acid and 233 ion-exchanged water were added to the reactor. .4 g of the mixed solution was added dropwise over 6 hours, and at the same time, an aqueous solution in which 18.9 g of 30% hydrogen peroxide was dissolved in 71.6 g of water and 7.3 g of L-ascorbic acid were dissolved in 74.2 g of water. The aqueous solution was added dropwise over 7 hours.
After completion of dropping, the reaction mixture was maintained at 70 ° C. for 1 hour. Furthermore, the polycarboxylic acid (10) in the present invention having a weight average molecular weight of 23400 in terms of polyethylene glycol by gel permeation chromatography was obtained by adjusting the pH of the reaction mixture to 7 with sodium hydroxide.
When the mass of the gel adhering to the polymerization reaction solution and to the reaction solution, stirring blade, thermometer and the like after polymerization was confirmed, 0.2 g / 1000 g polymer aqueous solution gel was observed.
The mass of the gel is the gel concentration in the water-containing state of the gel remaining on the filter when the polymerization reaction solution is filtered through a 100 mesh metal filter after polymerization and the gel adhering to the reaction vessel, stirring blade, thermometer, etc. is there.
The obtained polymer aqueous solution had a solid content of 48.3%.

Comparative Example 3
46 obtained by polymerizing 1025.6 g of water and Preparation Example 1 in a glass reaction vessel (internal volume: 3 liters) equipped with a thermometer, stirrer, dropping funnel, nitrogen introducing tube, and reflux condenser (condenser) .431.7 g of a 1% polymer aqueous solution was charged, and the reactor was purged with nitrogen under stirring, and the temperature was raised to 70 ° C. in a nitrogen atmosphere. Next, 1100.8 g of methoxypolyethylene glycol monomethacrylate (average number of added moles of ethylene oxide 4), 200.7 g of methacrylic acid, 67.7 g of sodium methacrylate, 15.4 g of 3-mercaptopropionic acid and ion-exchanged water were added to the reactor. 233.4 g of the mixed solution was dropped over 6 hours, and at the same time, an aqueous solution in which 18.9 g of 30% hydrogen peroxide was dissolved in 71.6 g of water and 7.3 g of L-ascorbic acid were dissolved in 74.2 g of water. The aqueous solution was added dropwise over 7 hours.
After completion of dropping, the reaction mixture was maintained at 70 ° C. for 1 hour. Furthermore, the polycarboxylic acid (11) in the present invention having a weight average molecular weight of 23,000 in terms of polyethylene glycol by gel permeation chromatography was obtained by adjusting the pH of the reaction mixture to 7 with sodium hydroxide.
When the mass of the gel adhering to the polymerization reaction solution and to the reaction solution, stirring blade, thermometer and the like after polymerization was confirmed, 0.2 g / 1000 g polymer aqueous solution gel was observed.
The mass of the gel is the gel concentration in the water-containing state of the gel remaining on the filter when the polymerization reaction solution is filtered through a 100 mesh metal filter after polymerization and the gel adhering to the reaction vessel, stirring blade, thermometer, etc. is there.
The resulting polymer aqueous solution had a solid content of 48.9%.

Concrete test condition It shows below using polycarboxylic acid (2), (8), (9), (10), (11) shown in Example 1, Production Examples 1 and 2 and Comparative Examples 2 and 3. Concrete was prepared by mixing and kneaded, and concrete tests were performed using cement compositions (1), (Comparative 4), and (Comparative 5).

Concrete test method Using the polycarboxylic acids (2), (8), (9), (10) and (11) shown in Example 1, Production Examples 1 and 2 and Comparative Examples 2 and 3, as follows Cement admixtures were prepared, concrete was mixed and kneaded in the following composition, and slump flow values were evaluated immediately after kneading and over time.

The concrete blending unit water amount is 172 kg / m ^{3 of} water, cement (ordinary Portland cement manufactured by Taiheiyo Cement Co., Ltd.): 573.3 kg / m ³ , coarse aggregate (Ome fossil): 861.5 kg / m ³ , fine bone Lumber (mixture of Oigawa river sand and Chiba Kimitsu sand, mixing ratio: Oigawa: Kimitsu = 80: 20): 739.4 kg / m ³ .
Defoaming agent Microair MA404 (manufactured by Pozzolith Products Co., Ltd.) is 0.02% based on the cement mass, and AE agent Microair MA202 (made by Pozzolith Products Co., Ltd.) is 0.003% based on the cement mass. Was formulated. The blending amount of the cement admixture with respect to the cement mass was calculated by the solid content of the admixture and expressed in% (mass%).

Concrete production conditions In the above composition, cement and fine aggregate were put into a 50 L biaxial forced kneading mixer and kneaded for 10 seconds, and then kneaded for 90 seconds by adding water containing a cement admixture. Coarse aggregate was added and kneaded for 90 seconds to produce concrete.

Evaluation Method The slump flow value of the obtained concrete and the measurement of the air amount were performed in accordance with Japanese Industrial Standards (JIS A1101, 1128, 6204).

In the most preferable form, the amount of slump change in Admixture 1 and Tables 4 and 5 in Table 2 is observed.
In the table, each of polycarboxylic acids (10) and (11) is a polymer obtained by polymerizing a polymer having a chain length of 10 in a kettle (average value 19 of hydrophilic / lipophilic balance of polyoxyalkylene glycol monomer of kettle polymer) .3, side chain length 10).
On the other hand, the polycarboxylic acid (2) was a polymer obtained by polymerizing a polymer having a chain length of 4 in a kettle (average value of 18.4 of the hydrophilic / lipophilic balance of the polyoxyalkylene glycol mormer of the kettle polymer) Side chain length 10).
Looking at the slump values in the table, the amount of decrease (slump loss) of the 0 and 30 minute numbers is:
Admixture 1: 22.5-22.0 = 0.5
Comparison 4: 22.5-20.5 = 2.0
Comparison 5: 22.5-21.0 = 1.5
And the reduction width of the admixture 1 is the lowest.
That is, a polymer with a shorter chain length is less slump loss and better in retention.
This is an advantage when a polymer having a short chain length is charged. That is, in the production method of the present invention, a polycarboxylic acid-based concrete admixture containing only a polymer having a short chain length of a (poly) oxyalkylene group can be obtained. The effects as described above will be exhibited.

On the other hand, the merits of performing polymerization with a single composition will be described. For example, in the case of continuous polymerization, when a polymer having a chain length of 4 is prepared by charging 20% by mass of a polymer having a chain length of 6 at the first time. A chain length of 6 / chain length of 4 = 20/80 is obtained.
If this is used for the second potting, the composition of the polymer having a chain length of 6 will inevitably drop. For example, when 20% by mass of the first polymer is initially charged, the first pot (content chain length 6 / chain length 4 = 20/80) / chain length 4 polymer = 20/80 is the second time. The polymer that can be produced is a polymer having a chain length of 6 / chain length of 4 = 4 (= 20/100 × 20 mass%) / 96 (= 80 mass% + 20/100 × 80 mass%), which is different from the first polymer.
If the polymerization is carried out with a single composition, a continuous and stable quality can be provided without any change in the composition of the polymer mixture as described above.

From the examples and comparative examples described above, it was found that the critical significance of the numerical range of the present invention can be said as follows. That is, a method for producing a polycarboxylic acid-based concrete admixture including a polymerization step in which a monomer component is polymerized in the presence of a solvent to obtain a polycarboxylic acid-based polymer,
The polymerization step is a polymerization in which a mixture containing a water-soluble polymer and water is used in advance as a solvent, and the water-soluble polymer is a monomer component having an average hydrophilic-lipophilic balance of less than 19 It was found that by obtaining a polymerized polymer, it produced an advantageous effect in stabilizing the retention and quality while suppressing the gel formation during the polymerization, and this was remarkable.

Regarding the technical significance of the upper limit of the numerical range, the average value of the hydrophilic / lipophilic balance in Example 1 is 18.4, and Comparative Examples 2 and 3 (the average value of the hydrophilic / lipophilic balance is higher than that value). This is clear when compared with 19.3). The amount of gel produced was the same level as in Comparative Examples 2 and 3 and Example 1, and the cement admixture containing the polycarboxylic acids (10) and (11) obtained in Comparative Examples 2 and 3 was As described above, the slump loss is large, whereas the polycarboxylic acid (2) obtained in Example 1 has a small slump loss. It goes without saying that such an effect, that is, an effect that a polycarboxylic acid polymer can be industrially produced and used in applications such as a polycarboxylic acid concrete admixture is outstanding. Absent.

Claims (9)

A method for producing a polycarboxylic acid-based concrete admixture comprising a polymerization step of polymerizing a monomer component in the presence of a solvent to obtain a polycarboxylic acid-based polymer,
The polymerization step is carried out using a mixture containing a water-soluble polymer essentially containing a monomer unit having a (poly) oxyalkylene group having an average hydrophilic / lipophilic balance of less than 19 and water as a solvent. And
The hydrophilic / lipophilic balance has the following formula:
Hydrophilic / lipophilic balance = (molecular weight of hydrophilic group) / (total molecular weight) × 100/5 = (mass% of hydrophilic group) / 5
Sought by
The method for producing a polycarboxylic acid-based concrete admixture, wherein the oxyalkylene group constituting the (poly) oxyalkylene group is an oxyethylene group and / or an oxypropylene group . A method for producing a polycarboxylic acid-based concrete admixture comprising a polymerization step of polymerizing a monomer component in the presence of a solvent to obtain a polycarboxylic acid-based polymer,
In the polymerization step, polymerization is performed using a mixture containing a water-soluble polymer having a (poly) oxyalkylene group having an average addition mole number of oxyalkylene group of less than 7 and water as a solvent in advance .
The method for producing a polycarboxylic acid-based concrete admixture, wherein the oxyalkylene group constituting the (poly) oxyalkylene group is an oxyethylene group and / or an oxypropylene group . The method for producing a polycarboxylic acid-based concrete admixture according to claim 1 or 2, wherein in the polymerization step, a monomer component is dropped into the solvent. The method for producing a polycarboxylic acid-based concrete admixture according to any one of claims 1 to 3, wherein the water-soluble polymer contained in the mixture previously used as a solvent is a polycarboxylic acid-based polymer. . The polycarboxylic acid polymer contained in the mixture used in advance as the solvent and the polycarboxylic acid polymer obtained by the polymerization step are the same or different and represented by the following general formula (1) (poly) It is obtained by polymerizing a monomer component containing an unsaturated monomer (A) having an oxyalkylene group and an unsaturated carboxylic acid monomer (B). 4. A method for producing a polycarboxylic acid-based concrete admixture according to 4.

In General Formula (1), R ¹ and R ² are the same or different and each represents a hydrogen atom or a methyl group. R ³ represents a hydrogen atom, a methyl group, or a —X—O (R ^a O) _m —R ⁴ group. R ⁴ is the same or different and represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. R ^a is the same or different and represents an alkylene group having 2 to 18 carbon atoms. m is the same or different and represents the average number of added moles of the oxyalkylene group represented by R ^a O, and is a number of 1 to 300. X is the same or different and represents a divalent alkylene group having 1 to 5 carbon atoms, or when the group represented by R ¹ R ³ C═CR ² — is a vinyl group, This means that the carbon and oxygen atoms are directly bonded. X may be a —CO— bond. In the polymerization step, the average addition number m of oxyalkylene groups in the polycarboxylic acid polymer contained in the mixture used as a solvent in advance and the average addition of oxyalkylene groups in the polycarboxylic acid polymer obtained by the polymerization step 6. The method for producing a polycarboxylic acid concrete admixture according to claim 5, wherein the polymerization is carried out so that the number of moles m is the same. A monomer composition for obtaining a polymer obtained by polymerizing a polycarboxylic acid polymer contained in a mixture used as a solvent in advance, and a unit for obtaining a polymer obtained by polymerizing the polycarboxylic acid polymer obtained by the polymerization step. The method for producing a polycarboxylic acid-based concrete admixture according to claim 6, wherein the composition is the same as the monomer composition. A method for producing a polycarboxylic acid-based concrete admixture comprising a polymerization step of polymerizing a monomer component in the presence of a solvent to obtain a polycarboxylic acid-based polymer,
The method for producing a polycarboxylic acid-based concrete admixture according to claim 1 or 2, wherein in the polymerization step, polymerization is carried out in the presence of a polymerization initiator and / or a chain transfer agent in advance in a solvent. A method for producing a polycarboxylic acid-based concrete admixture comprising a polymerization step of polymerizing a monomer component in the presence of a solvent to obtain a polycarboxylic acid-based polymer,
The production method includes a water-solubility essentially comprising a monomer unit having a (poly) oxyalkylene group having an average hydrophilic-lipophilic balance of less than 19 in advance in the reaction vessel before introducing the monomer into the reaction vessel. A mixture containing a water-soluble polymer having water and a water-soluble polymer having a (poly) oxyalkylene group having an average number of added moles of the polymer and / or oxyalkylene group of less than 7 and water. A step of preparing
Adding an unsaturated monomer (A) having a (poly) oxyalkylene group to a mixture containing the water-soluble polymer obtained in the step and water;
Have a adding an unsaturated carboxylic acid monomer (B), the mixture comprising the water-soluble polymer and water obtained in the step,
The hydrophilic / lipophilic balance has the following formula:
Hydrophilic / lipophilic balance = (molecular weight of hydrophilic group) / (total molecular weight) × 100/5 = (mass% of hydrophilic group) / 5
Sought by
The method for producing a polycarboxylic acid-based concrete admixture, wherein the oxyalkylene group constituting the (poly) oxyalkylene group is an oxyethylene group and / or an oxypropylene group .