JP2015051900A - Method for producing thiol-modified monomer, polyalkylene glycol chain-containing thiol-based polymer, and dispersant and cement admixture using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for providing a cement admixture which can exhibit high dispersion performance.SOLUTION: The method for producing a thiol-modified monomer comprises a step of obtaining a thiol-modified monomer represented by the general formula (3) by subjecting a mercaptocarboxylic acid represented by the general formula (1) and a polyalkylene glycol represented by the general formula (2) to an esterification reaction in the presence of an acid catalyst as a dehydration catalyst. The object can be solved by carrying out a step of neutralizing the acid catalyst with an alkali in absence of a solvent.

Description

  The present invention relates to a method for producing a thiol-modified monomer, a polyalkylene glycol chain-containing thiol polymer, and a dispersant and a cement admixture using the same.

  A mercapto group (thiol group, SH group) is a functional group useful for organic synthesis because of its unique reactivity. Therefore, thiol compounds having at least one mercapto group in the molecule are used for various applications by utilizing the unique reactivity of the mercapto group. For example, a mercapto group has been introduced into polyalkylene glycol as an extension of the application field of polyalkylene glycol, which has been useful for applications such as adhesives and sealants as soft segments, and components that impart flexibility to various polymers. A thiol-modified product of polyalkylene glycol obtained in this manner has attracted attention.

  By the way, as an application field of polyalkylene glycol, in recent years, cement compositions (cement paste in which water is added to cement, mortar in which fine aggregate sand is mixed in cement paste, and pebbles in coarse aggregate are mixed in mortar. Cement admixtures added to concrete, etc.) have been studied. Such a cement admixture is usually used as a water reducing agent or the like, and exerts the action of improving the strength and durability of the cured product by reducing the cement composition by increasing the fluidity of the cement composition. It is used for that purpose.

  Conventional cement admixtures include, for example, naphthalene cement admixtures and polycarboxylic acid cement admixtures. For example, unsaturated carboxylic acid monomers and unsaturated polyalkylene glycol ether single monomers. A copolymer for cement admixture obtained by copolymerizing with a monomer is disclosed (for example, see Patent Document 1). In this copolymer for cement admixture, the carboxyl group derived from the unsaturated carboxylic acid monomer becomes an adsorbing group that adsorbs to the cement particles, and the polyalkylene glycol derived from the unsaturated polyalkylene glycol ether monomer. The chain acts as a dispersing group for dispersing cement particles, and the steric repulsion of the polyalkylene glycol chain makes it possible to provide a cement admixture that exhibits a certain degree of dispersion performance.

  However, in order to further reduce the amount of cement admixture used, the development of a cement admixture that can exhibit even higher dispersion performance is required.

  On the other hand, as a conventional technique for producing a thiol-modified product (thiol-modified monomer) of polyalkylene glycol, for example, in Patent Documents 2 to 5, a polyalkylene glycol has a carboxyl group and a mercapto group in one molecule. A technique of esterifying a compound having a compound (mercaptocarboxylic acid) is disclosed.

JP 2001-220417 A JP 2008-266620 A JP 2008-266621 A JP 2010-065146 A JP 2010-070687 A

  The present invention has been made in view of the situation of the background art as described above, and an object thereof is to provide an excellent thiol-modified monomer of polyalkylene glycol that can be used as a raw material for compounds for various uses. . Another object of the present invention is to provide a polymer obtained by using a thiol-modified monomer that can exhibit high dispersion performance and can provide an excellent dispersant (particularly a cement admixture). .

  The present inventors have intensively studied to solve the above problems. In this process, the present inventor esterifies polyalkylene glycol and mercaptocarboxylic acid, which are raw materials, in the presence of an acid catalyst as a dehydration catalyst in producing a thiol-modified polyalkylene glycol (thiol-modified monomer). After the reaction, an attempt was made to carry out a step of neutralizing the acid catalyst with an alkali in the absence of a solvent. As a result, it was surprisingly found that the polymer produced using the thiol-modified monomer produced in this way is excellent in performance as a cement admixture. And based on this knowledge, it came to complete this invention.

  That is, one form of this invention is the following general formula (1):

(Wherein R ¹ and R ² are the same or different and represent an organic residue)
A mercaptocarboxylic acid represented by the following general formula (2):

(In the formula, AO is the same or different and represents one or more oxyalkylene groups having 2 to 18 carbon atoms. M represents the average number of moles of oxyalkylene groups and is an integer of 10 to 500. is there)
Is subjected to an esterification reaction in the presence of an acid catalyst as a dehydration catalyst, and the following general formula (3):

(In the formula, R ¹ and R ² are the same or different and represent an organic residue. AO is the same or different and represents one or more oxyalkylene groups having 2 to 18 carbon atoms. M Represents the average number of moles of the oxyalkylene group and is an integer of 10 to 500)
The manufacturing method of the thiol modified monomer including the process of obtaining the thiol modified monomer represented by these. And the manufacturing method which concerns on this invention has the characteristics in the point which further includes the process of neutralizing the said acid catalyst with an alkali in the absence of a solvent.

  By using the thiol-modified monomer produced by the production method according to the present invention, a cement admixture polymer that can exhibit high dispersion performance is provided. As a result, the present invention also provides a cement admixture that can exhibit high dispersion performance. The cement admixture can reduce the blending amount when preparing the cement composition, and thus does not impair the excellent properties of the cement. As described above, the method for producing a thiol-modified monomer according to the present invention, the polymer obtained by using the monomer obtained thereby, and the dispersant (especially cement admixture) using them are civil engineering for handling concrete. -It will make a great contribution in the construction field.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

<< Method for producing thiol-modified monomer >>
One embodiment of the present invention is the following general formula (1):

A mercaptocarboxylic acid represented by the following general formula (2):

Is subjected to an esterification reaction in the presence of an acid catalyst as a dehydration catalyst, and the following general formula (3):

The manufacturing method of the thiol modified monomer including the process of obtaining the thiol modified monomer represented by these. And the manufacturing method which concerns on this invention has the characteristics in the point which further includes the process of neutralizing the said acid catalyst with an alkali in the absence of a solvent.

  Hereinafter, the details of the method for producing a thiol-modified monomer according to the present invention will be described step by step for each step of the raw material and method.

《Mercaptocarboxylic acid》
One of the raw materials is the following general formula (1):

It is a mercaptocarboxylic acid represented by. If only one kind of mercaptocarboxylic acid is used, R ¹ = R ² in general formula (3), and a thiol-modified monomer having the same thiol-containing functional group introduced at both ends is produced. On the other hand, when two (or more) mercaptocarboxylic acids are used, a thiol-modified monomer that satisfies R ¹ ≠ R ² in the general formula (3) can be produced.

In the general formula (1) (and general formula (3)), R ¹ and R ² are the same or different and represent an organic residue. This “organic residue” can be appropriately changed depending on the production mode of the thiol-modified monomer of the general formula (3), which is the final product, and is not particularly limited. Examples of such an organic residue include a divalent group derived from an aromatic group such as benzene, alkylbenzene, pyridine, thiophene, pyrrole, furan, and thiazole in addition to a linear or branched alkylene group having 1 to 18 carbon atoms. And the like. In the present invention, the production of the thiol-modified monomer includes the mercaptocarboxylic acid represented by the general formula (1) (a compound having a carboxyl group and at least one thiol group in the same molecule), the general formula Since R ¹ and R ² described above are carried out by esterification with the polyalkylene glycol represented by (2), the above-mentioned mercaptocarboxylic acid residue (excluding the carboxyl group from the mercaptocarboxylic acid of the general formula (1)) Monovalent organic residues). The hydrogen atom contained in R ¹ and R ² may be partially substituted with a hydroxy group, amino group, cyano group, carbonyl group, carboxyl group, halogen group, sulfonyl group, nitro group, formyl group, or the like. Good.

  The mercaptocarboxylic acid represented by the general formula (1) includes thioglycolic acid (mercaptoacetic acid) 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptoisobutyric acid, thiomalic acid, mercaptostearic acid, mercaptoacetic acid, Examples include mercaptobutyric acid, mercaptooctanoic acid, mercaptobenzoic acid, mercaptonicotinic acid, cysteine, N-acetylcysteine, mercaptothiazole acetic acid and the like. Among these, thioglycolic acid, 3-mercaptopropionic acid, thiomalic acid, and mercaptoisobutyric acid are preferable.

《Polyalkylene glycol》
Another one of the raw materials is the following general formula (2):

It is polyalkylene glycol represented by these.

  In the above general formula (2) (and general formula (3)), AO is the same or different and represents one or more oxyalkylene groups having 2 to 18 carbon atoms, and is not particularly limited. . Moreover, when AO is comprised from 2 or more types of oxyalkylene groups, these oxyalkylene groups may be introduce | transduced in the block form or random.

When the thiol-modified monomer obtained by the production method of the present invention is used for producing a cement admixture component, AO mainly has about 2 to 8 carbon atoms from the viewpoint of affinity with cement particles. A relatively short-chain oxyalkylene group is preferred. More preferably, it is mainly an oxyalkylene group having 2 to 4 carbon atoms, and more preferably an oxyalkylene group (oxyethylene group) mainly having 2 carbon atoms. Particularly preferred is an embodiment containing 75% by mass or more of oxyethylene groups with respect to 100% by mass of all oxyalkylene groups constituting the oxyalkylene chain represented by — (AO) _m —. With this configuration, the thiol-modified monomer has higher hydrophilicity.

  By including an oxyalkylene group having 3 or more carbon atoms in the oxyalkylene chain, a certain degree of hydrophobicity is imparted to the thiol-modified monomer. When a cement admixture is obtained using such a thiol-modified monomer, it is possible to bring some structure (network) to the cement particles and reduce the viscosity and stiffness of the cement composition.

  Considering the balance between the performance of dispersing cement particles and the reduction in the viscosity and stiffness of the cement composition, the proportion of oxyalkylene groups having 3 or more carbon atoms in the oxyalkylene chain is 100% by mass of the oxyalkylene chain. 30% by mass or less is preferable. More preferably, it is 25 mass% or less, More preferably, it is 20 mass% or less, Most preferably, it is 5 mass% or less.

  Depending on the application of the thiol-modified monomer of the present invention, an embodiment that does not contain an oxyethylene group having 3 or more carbon atoms may be preferable.

In the compound represented by the general formula (3), the ester bond may be cleaved by hydrolysis. When improvement in hydrolysis resistance is required, it is preferable to introduce an oxyalkylene group having 3 or more carbon atoms at the end of-(AO) _m- .

  Examples of the oxyalkylene group having 3 or more carbon atoms include an oxypropylene group, an oxybutylene group, an oxystyrene group, and an alkyl glycidyl ether residue. Of these, an oxypropylene group and an oxybutylene group are preferable because of ease of production.

The introduction amount of the oxyalkylene group having 3 or more carbon atoms depends on the required degree of hydrolysis resistance, but the introduction amount is preferably 50% or more with respect to both ends of — (AO) _m —. Yes. More preferably, it is 100% or more, More preferably, it is 150% or more, Especially preferably, it is 200% or more.

In order to improve hydrolysis resistance, it is preferable that the terminal of-(AO) _m- is a secondary alcohol residue. A known method may be used to introduce a secondary alcohol group to the terminal of-(AO) _m- . For example, an alkylene having 3 or more carbon atoms is added to polyalkylene glycol as a raw material of-(AO) _m-. An oxide may be added. In this addition reaction, in order to increase the rate of introduction of secondary alcohol groups, at least one selected from the group consisting of alkali metals, alkaline earth metals and oxides or hydroxides thereof is used as a catalyst. It is preferable to use a compound. More preferred are sodium hydroxide, potassium hydroxide, magnesium hydroxide and calcium hydroxide, and most preferred are sodium hydroxide and potassium hydroxide.

  The reaction temperature during the addition reaction is preferably 50 to 200 ° C. in order to increase the introduction rate of secondary alcohol groups. More preferably, it is 70-170 degreeC, More preferably, it is 90-150 degreeC, Most preferably, it is 100-130 degreeC.

  In the oxyalkylene chain, the average number of moles (average number of added moles) of the oxyalkylene group represented by m is an integer of 10 to 500. Preferably it is 20 or more, More preferably, it is 30 or more, More preferably, it is 40 or more, Most preferably, it is 50 or more. The upper limit of m is not particularly limited, but m is suitably 500 or less from the viewpoints of handleability and reactivity. Preferably it is 400 or less, more preferably 350 or less, more preferably 300 or less, even more preferably 280 or less, even more preferably 250 or less, particularly preferably 220 or less, most preferably Is 200 or less.

The thiol-modified monomer is also adjusted by appropriately adjusting R ¹ and / or R ^{2 in the} general formula (3) and m, so that AO in the formula is 50 mass in 100 mass% of the thiol-modified monomer. It is preferable to occupy at least%. Thereby, since the contribution rate of AO in the thiol-modified monomer is increased, the characteristics of the thiol-modified monomer of the present invention can be easily adjusted by appropriately selecting AO. Thus, a form in which the oxyalkylene group represented by AO occupies 50% by mass or more in 100% by mass of the thiol-modified monomer is also a preferred form of the present invention.

<< Esterification reaction process >>
The method for producing a thiol-modified monomer according to the present invention comprises using a mercaptocarboxylic acid represented by the above general formula (1) and a polyalkylene glycol represented by the above general formula (2) as an acid as a dehydration catalyst. It includes a step of performing an esterification reaction under a catalyst to obtain a thiol-modified monomer represented by the above general formula (3) (also referred to as “esterification reaction step” in the present specification). By adopting such a production method, a high molecular weight thiol-modified monomer can be obtained easily and efficiently at low cost.

  The esterification reaction step is a step in which the above-described mercaptocarboxylic acid (general formula (1)) and the above-described polyalkylene glycol (general formula (2)) are esterified. The said process can be performed using the normal method of the ester reaction in a normal liquid phase. Further, for example, the pressure may be reduced or an entrainer such as xylene may be used.

  Here, in the production method according to the present invention, the esterification reaction step is performed in the presence of an acid catalyst. As the acid catalyst, metal and semimetal halogen compounds which are Lewis acid catalysts such as boron trifluoride; mineral acids such as hydrogen chloride, hydrogen bromide and sulfuric acid; paratoluenesulfonic acid and the like are suitable.

  The mixing ratio of the raw materials may be selected as follows according to the purity and cost of the desired thiol-modified monomer and the synthesis method.

  For example, when it is desired to obtain a highly pure product (thiol-modified monomer) in a short time, the molar ratio of the carboxyl group possessed by the mercaptocarboxylic acid to the amount of hydroxy group provided for the reaction possessed by the polyalkylene glycol. It is preferable to make a large excess. Specifically, from the viewpoint of reaction rate, the molar ratio is preferably 2 times or more, more preferably 3 times or more, and from the viewpoint of production cost, it is preferably 10 times or less, More preferably, it is 5 times or less. In addition, although the crude product after reaction may be used as it is, it may refine | purify as needed and an unreacted substance may be removed.

  As for the mixing ratio, when it is desired to reduce the amount of the crude product after the reaction, the carboxyl group of the mercaptocarboxylic acid is doubled in molar ratio with respect to the amount of hydroxy group to be subjected to the reaction of the polyalkylene glycol. The following is preferable. Specifically, from the viewpoint of yield, the molar ratio is preferably 0.3 times or more, more preferably 0.5 times or more, still more preferably 0.7 times or more, particularly preferably 0.8. From the viewpoint of the remaining amount of unreacted material, it is preferably 1.8 times or less, more preferably 1.6 times or less, still more preferably 1.4 times or less, and particularly preferably 1 Less than 3 times. Although the crude product after the reaction may be purified as necessary, since the amount of unreacted mercaptocarboxylic acid is small in this method, the operation for removing this is often omitted, and the production process is further improved. It can be simplified.

  What is necessary is just to set the reaction time of the said esterification reaction process suitably according to the kind and quantity of the acid catalyst to be used, the mixing ratio of raw materials, solution concentration, etc.

  The esterification reaction step may be performed in the absence of a solvent (“Production Example 1” in Examples described later) or may be performed in the presence of a dehydrating solvent (“Production Example 2” in Examples described later). ). Here, the “dehydrated solvent” is defined as a solvent azeotropic with water. That is, by using a dehydrating solvent, the reaction product water produced by the esterification reaction can be dehydrated by azeotropic distillation. Examples of the dehydrating solvent include benzene, toluene, xylene, cyclohexane, dioxane, pentane, hexane, heptane, chlorobenzene, isopropyl ether and the like, and these can be used alone or as a mixed solvent. . Among these, those having an azeotropic temperature with water of 150 ° C. or lower, more preferably in the range of 60 to 90 ° C. are preferable, and specifically, cyclohexane, toluene, dioxane, benzene, isopropyl ether, hexane, heptane, and the like. Can be mentioned. The embodiment of the neutralization step to be described later differs depending on whether the esterification reaction step is performed in the presence or absence of a dehydrating solvent.

  Here, the thiol group is easily oxidized to form a multimerized product particularly under alkaline conditions. Therefore, in the production method according to the present invention, it is preferable to add an antioxidant to the reaction system in order to prevent the raw material mercaptocarboxylic acid and the product monomer from increasing in number.

  As the antioxidant, a commonly used antioxidant may be used, and is not particularly limited. For example, phenothiazine and derivatives thereof; hydroquinone, catechol, resorcinol, methoquinone, butylhydroquinone, butylcatechol, Phenolic compounds such as naphthohydroquinone, dibutylhydroxytoluene, butylhydroxyanisole, tocopherol, tocotrienol, catechin; nitro compounds such as tri-p-nitrophenylmethyl, diphenylpicrylhydrozine, picric acid; nitroso compounds such as nitrosobenzene and cuperone Amine compounds such as diphenylamine, di-p-fluorophenylamine, N- (3-N-oxyanilino-1,3-dimethylbutylidene) aniline oxide; TEMPO Stable radicals such as cal (2,2,6,6-tetramethylyl-1-diphenylpicylylyl), diphenylpicrylhydrazyl, galvinoxyl, ferdazil; alcorbic acid, erythorbic acid and salts or esters thereof; dithiobenzoyl disulfide; copper chloride (II ); Thiols such as mercaptoethanol, dithiothreitol, glutathione; Tris (2-carboxyethyl) phosphine hydrochloride and the like. These may be used alone or in combination of two or more. Among them, phenothiazine and its derivatives, phenolic compounds, ascorbic acid, erythorbic acid and esters thereof, which are compounds that can more effectively function as radical scavengers and polymerization inhibitors, are preferred, and phenothiazine, hydroquinone, and methoquinone are preferred. More preferred.

  The amount of the antioxidant added is not particularly limited as long as the increase in the amount of mercaptopropionic acid or thiol-modified monomer can be effectively prevented. As an example, the amount of the antioxidant is preferably 10 ppm or more, more preferably 20 ppm or more, still more preferably 50 ppm, particularly preferably 100 ppm or more with respect to the mass (solid content) of the thiol-modified monomer obtained. In addition, it is preferably 5000 ppm or less, more preferably 2000 ppm or less, still more preferably 1000 ppm or less, and particularly preferably 500 ppm or less.

  The antioxidant may be added at any stage of production, for example, in the esterification reaction or when a solid product of the reaction crude product is obtained from the reaction solution. Among these, it is more preferable to add an antioxidant during the esterification reaction.

<< Neutralization process >>
The production method according to the present invention is characterized in that it further includes a step of neutralizing the acid catalyst with an alkali in the absence of a solvent (also referred to as “neutralization step” in the present specification). This is because the production method according to the present invention requires a step of neutralizing the acid catalyst used in the esterification reaction step (neutralization step), but the neutralization step is performed "without solvent". It means that the content in the neutralization reaction system of components other than raw material components, products, by-products, and water that can function as a solvent is 1000 mass ppm or less.

  As described above, when the esterification reaction step is performed in the absence of a solvent (“Production Example 1” in Examples described later), the neutralization step should be performed in the absence of a solvent unless a solvent component is separately added. become. When the esterification reaction step is performed in the presence of a dehydrating solvent (“Production Example 2” in the examples described later), the esterification reaction step is performed so as to satisfy the definition of “under no solvent” after completion of the esterification reaction step. A solvent process is performed, followed by a neutralization process.

  According to the study by the present inventors, surprisingly, when the neutralization step is performed in the absence of a solvent in this way, the polymer produced using the produced thiol-modified monomer becomes a cement admixture. It was found that the performance is excellent.

(Production Example 1)
First, in the case where the esterification reaction step is performed in the absence of a solvent, the neutralization step adds the alkali to the reaction product after cooling the reaction product obtained in the esterification reaction step as necessary. Can be done. In this case, the alkali used as a neutralizing agent is not particularly limited, and a conventionally known alkali can be used. In particular, it is preferable to use at least one compound selected from the group consisting of alkali metals, alkaline earth metals and oxides or hydroxides thereof as described above. More preferred are alkali metal hydroxides and / or alkaline earth metal hydroxides, still more preferably sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, most preferably sodium hydroxide. Potassium hydroxide. These alkalis may be added as they are in a solid state, but are preferably added as an aqueous solution.

  There is no restriction | limiting in particular also about the addition amount of the alkali in a neutralization process, It can set suitably considering the desired pH of the reaction material obtained through a neutralization process. Although there is no restriction | limiting in particular also about the pH of the reaction material after a neutralization process, From a viewpoint of suppressing hydrolysis of ester, it is preferable to set it as 3 or more, More preferably, it is 4 or more. Moreover, it is preferable to set it as 8 or less, More preferably, it is 7 or less, More preferably, it is 6 or less, Especially preferably, it is 5.5 or less. As a preferred form of the amount of alkali used based on the amount of acid catalyst, from the viewpoint of the stability of the thiol group, the amount of alkali used is preferably 0.95 to 1.20 equivalents relative to the acid catalyst, More preferably, it is 0.98 to 1.10 equivalent.

  In addition, the solidified product of the thiol-modified monomer tends to increase in quantity when dried. For this reason, it is preferable to store the obtained thiol-modified monomer in a solution state, and it is preferable to store it in an aqueous solution state at a pH of 4 or more and 5.5 or less.

  In the method for producing the thiol-modified monomer, the thiol-modified monomer is easily multimerized, and the thiol-modified monomer of the present invention includes a multimerized product. The process of removing may be included. Examples of methods for removing the multimerized product include molecular weight fractionation methods such as dialysis, ultrafiltration, and GPC fractionation. In addition, since the addition of the step of removing the multimerized product leads to an increase in manufacturing cost, the thiol-modified monomer containing the multimerized product may be used as it is, for example, for the preparation of a polymer described later. .

(Production Example 2)
When the esterification reaction step is performed in the presence of a dehydrating solvent, the solvent removal step is performed after the esterification reaction step so as to satisfy the definition of “under no solvent”. And the neutralization process using the above alkalis is performed with respect to the obtained reaction material.

  There is no restriction | limiting in particular about the detail of a desolvation process, A conventionally well-known knowledge can be referred suitably. As an example, in the desolvation step, desolvation is achieved by volatilizing the dehydrated solvent contained in the reactant by placing the reaction product (including dehydrated solvent) obtained in the esterification reaction step under reduced pressure. Can do. At this time, if unreacted mercaptocarboxylic acid as a raw material remains in the reaction product, it is volatilized and removed in the same manner in the solvent removal step.

<< Polyalkylene glycol chain-containing thiol polymer >>
According to another embodiment of the present invention, it is also referred to as an unsaturated carboxylic acid monomer (hereinafter referred to as “monomer (a)”) in the presence of a thiol-modified monomer as obtained by the above production method. ) And an unsaturated (poly) alkylene glycol monomer (hereinafter also referred to as “monomer (b)”). Coalescence is also provided.

  Such a polymer is bonded to the polyalkylene glycol chain (polyalkylene glycol chain (1)) derived from the thiol-modified monomer and at least one end of the polyalkylene glycol chain (1) via a sulfur atom-containing group. And a polymer portion containing a structural unit derived from the unsaturated monomer component.

  With regard to such a structure, for example, when at least the unsaturated carboxylic acid monomer (a) is used as the unsaturated monomer component, the monomer ( Since it has a carboxyl group derived from a), it is considered that the cement particle adheres to the cement particle via the carboxyl group, and the cement particle can be effectively dispersed by the steric repulsion of the polyalkylene glycol chain (1). When at least the unsaturated (poly) alkylene glycol monomer (b) is used as the unsaturated monomer component, the monomer (b) is derived from both ends of the polyalkylene glycol chain (1). Since the polyalkylene glycol chain (polyalkylene glycol chain (2)) has a steric repulsion of the polyalkylene glycol chain (2) in addition to the steric repulsion of the polyalkylene glycol chain (1), the synergistic effect results in cement. It is considered that the performance of dispersing the particles is improved.

  In the unsaturated monomer component, examples of the unsaturated carboxylic acid monomer (a) include the following general formula (4):

(Wherein R ⁴ , R ⁵ and R ⁶ are the same or different and each represents a hydrogen atom, a methyl group or (CH ₂ ) _x COOM ² (wherein — (CH ₂ ) _x COOM ² represents —COOM ¹ or The other — (CH ₂ ) _x COOM ² may form an anhydride.) _X is an integer of 0 to ^2. M ¹ and M ² are the same or different and represent a hydrogen atom. Represents a monovalent metal, a divalent metal, a trivalent metal, a quaternary ammonium base or an organic amine base).

  Specific examples of the monomer (a) represented by the general formula (4) include, for example, monocarboxylic acid monomers such as acrylic acid, methacrylic acid, and crotonic acid; maleic acid, itaconic acid, and fumaric acid. Dicarboxylic acid monomers such as: anhydrides or salts of these carboxylic acids (for example, alkali metal salts, alkaline earth metal salts, trivalent metal salts, ammonium salts, organic amine salts) and the like. These monomers may be used alone or in combination of two or more. Among these monomers, acrylic acid, methacrylic acid, maleic acid, maleic anhydride and salts thereof are preferable from the viewpoint of polymerizability, and among them, acrylic acid, methacrylic acid and salts thereof are more preferable.

  Examples of the unsaturated (poly) alkylene glycol monomer (b) include the following formula (5):

(.AO ^wherein, R 7, ^{R 8} and ^{R 9} are the same or different, ^{.R 10} represents a hydrogen atom or a methyl group, represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms are the same Or, differently, it represents one type or two or more types of oxyalkylene groups having 2 to 18 carbon atoms (wherein two or more types of oxyalkylene groups are introduced in a random manner even if they are introduced in a block shape). Y is an integer of 0 to 2. z is 0 or 1. p represents the average number of moles added of the oxyalkylene group, and is an integer of 1 to 300. Are preferred.

In the general formula (5), R ¹⁰ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. Examples of the hydrocarbon group having 1 to 20 carbon atoms include, for example, a fatty acid having 1 to 20 carbon atoms. Group alkyl groups, alicyclic alkyl groups having 3 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, alkynyl groups having 2 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, and the like.

R ¹⁰ is also preferably not highly hydrophobic from the viewpoint of dispersibility of cement particles, and specifically, is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. More preferably, they are a hydrogen atom or a C1-C5 alkyl group, More preferably, they are a hydrogen atom or a C1-C3 alkyl group.

In the general formula (5), the oxyalkylene chain represented by — (AO) _p — corresponds to the above-described polyalkylene glycol chain (2). From the viewpoint of effectively dispersing the cement particles when blended in the agent, it is preferable to have higher hydrophilicity, and mainly an oxyalkylene group having 2 carbon atoms. The ratio of the oxyalkylene group having 2 carbon atoms in such an oxyalkylene chain (polyalkylene glycol chain (2)) is 50 mol% or more with respect to 100 mol% of all oxyalkylene groups constituting the oxyalkylene chain. Preferably, it is 70 mol% or more, more preferably 90 mol% or more, and particularly preferably 100 mol%.

  In the above oxyalkylene chain (polyalkylene glycol chain (2)), when a concrete composition is produced by blending with a cement admixture, the oxyalkylene chain can be reduced from the viewpoint of reducing the viscosity and stiffness of the concrete. It is preferable to introduce a slight structure (network) to the cement particles by introducing an oxyalkylene group having 3 or more carbon atoms into the chain to impart a certain degree of hydrophobicity.

  In consideration of the balance between dispersibility and reduction in viscosity and stiffness, the proportion of oxyalkylene groups having 3 or more carbon atoms in the oxyalkylene chain is 100 mol% of all oxyalkylene groups constituting the oxyalkylene chain. It is preferably 1 mol% or more, more preferably 3 mol% or more, further preferably 5 mol% or more, particularly preferably 7 mol% or more, and preferably 50 mol% or less. Is 30 mol% or less, more preferably 20 mol% or less, and particularly preferably 10 mol% or less.

  The oxyalkylene group having 3 or more carbon atoms in the oxyalkylene chain may be introduced in a block form or may be introduced in a random form (an oxyalkylene group having 2 or more carbon atoms). It is preferably introduced in the form of a block such as (alkylene chain)-(oxyalkylene chain comprising an oxyalkylene group having 3 or more carbon atoms)-(oxyalkylene chain comprising an oxyalkylene group having 2 or more carbon atoms).

  The oxyalkylene group having 3 or more carbon atoms is preferably an oxyalkylene group having 3 to 8 carbon atoms from the viewpoint of ease of introduction, affinity with cement particles, and the like. More preferred are oxypropylene groups having 3 carbon atoms and oxybutylene groups having 4 carbon atoms.

  In the oxyalkylene chain, the average added mole number of the oxyalkylene group represented by p is an integer of 1 to 300. Preferably it is 4 moles or more, more preferably 10 moles or more, more preferably 15 moles or more, even more preferably 20 moles or more, particularly preferably 25 moles or more, most preferably 30 moles or more, and preferably 250 moles. Below, more preferably 200 mol or less, still more preferably 150 mol or less, still more preferably 125 mol or less, particularly preferably 100 mol or less, most preferably 75 mol or less.

  Specific examples of the monomer (b) represented by the general formula (5) include, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 1 -Hexanol, octanol, 2-ethyl-1-hexanol, nonyl alcohol, lauryl alcohol, cetyl alcohol, stearyl alcohol and other saturated aliphatic alcohols having 1 to 20 carbon atoms, allyl alcohol, methallyl alcohol, crotyl alcohol, oleyl C3-C20 unsaturated aliphatic alcohols such as alcohol, C3-C20 alicyclic alcohols such as cyclohexanol, phenol, phenylmethanol (benzyl alcohol), methylphenol (cresol), p-ethyl Phenol, dimethylphenol (Renol), nonylphenol, dodecylphenol, phenylphenol, alkoxypolyalkylene glycols obtained by adding alkylene oxides having 2 to 18 carbon atoms to aromatic alcohols having 6 to 20 carbon atoms such as naphthol and the like An esterified product of (meth) acrylic acid or crotonic acid; an esterified product of a polyalkylene glycol obtained by polymerizing an alkylene oxide having 2 to 18 carbon atoms with (meth) acrylic acid or crotonic acid; Vinyl alcohol, allyl alcohol, methallyl alcohol, 3-buten-1-ol, 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-3-butene- 2-ol, 2-methyl-2-buten-1-ol, 2-methyl-3 An unsaturated ether compound obtained by adding 1 to 300 moles of alkylene oxide to an unsaturated alcohol such as buten-1-ol, hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, or hydroxybutyl vinyl ether can be used. Also, two or more of them may be used in combination. Of these, unsaturated esters are preferred, and esters of (meth) acrylic acid alkoxypolyalkylene glycols are preferred. Of these, compounds using (meth) allyl alcohol or 3-methyl-3-buten-1-ol are particularly preferred.

  In addition to the monomer (a) and the monomer (b), the unsaturated monomer component is also referred to as a copolymerizable monomer (hereinafter referred to as “monomer (c)”). ) May be included. As said monomer (c), the following 1 type (s) or 2 or more types can be used.

Unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid, and alkyl alcohols having 1 to 20 carbon atoms, glycols having 2 to 18 carbon atoms, or polyalkylene glycols having 2 to 300 addition moles of these glycols Or monoesters and diesters of an alkylene oxide having 2 to 300 addition moles of an alkylene oxide formed by adding an alkylene oxide having 2 to 18 carbon atoms to an alkyl alcohol having 1 to 20 carbon atoms;
Single-terminal aminated product of the above unsaturated dicarboxylic acids and alkylamines having 1 to 20 carbon atoms and glycols having 2 to 18 carbon atoms, or single-terminal aminated products of polyalkylene glycols having 2 to 300 addition moles of these glycols Monoamides and diamides with
Esters of unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid with alkyl alcohols having 1 to 20 carbon atoms;
Diesters of the above unsaturated carboxylic acids and glycols having 2 to 18 carbon atoms or polyalkylene glycols having 2 to 300 addition moles of these glycols;
Single-terminal aminated product of the above unsaturated monocarboxylic acid, alkylamine having 1 to 20 carbon atoms and glycol having 2 to 18 carbon atoms, or single-terminal amino group of polyalkylene glycol having 2 to 300 moles of addition of these glycols Amides with compounds;
Unsaturated sulfonic acids such as sulfoethyl acrylate, sulfoethyl methacrylate, 2-methylpropanesulfonic acid acrylamide, 2-methylpropanesulfonic acid methacrylamide, and styrenesulfonic acid, and monovalent metal salts, divalent metal salts, and ammonium thereof Salts and organic amine salts;
Unsaturated amides such as acrylamide, methacrylamide, acrylic alkylamide, methacrylalkylamide;
Unsaturated amino compounds such as dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate;
Vinyl esters such as vinyl acetate and vinyl propionate;
Vinyl ethers such as alkyl vinyl ethers having 3 to 20 carbon atoms such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether;
Aromatic vinyls such as styrene; etc.

  The amount of monomer (a), monomer (b) and monomer (c) used in the unsaturated monomer component is as follows: monomer (a) / monomer (b) / monomer When expressed as a ratio of (c) (unit: mass%, the sum of monomer (a) + monomer (b) + monomer (c) is 100), monomer (a) is the main component. In some cases, it is preferably 50 to 99/50 to 1/0 to 40, more preferably 55 to 95/45 to 5/0 to 40, and still more preferably 60 to 90/40 to 10/0. 40, particularly preferably 65 to 85/35 to 15/0 to 40. Moreover, when a monomer (b) is a main component, it is preferable that it is 1-50 / 99-50 / 0-40, More preferably, it is 2-40 / 98-60 / 0-40, Furthermore, Preferably it is 5-30 / 95-70 / 0-40, Most preferably, it is 7.5-25 / 92.5-75 / 0-40.

  The relationship between the thiol-modified monomer and the amount of the monomer (a), monomer (b) and monomer (c) used is (monomer (a) + monomer (b) + When the sum of the monomers (c)) is taken as 100%, the ratio of the thiol-modified monomer (unit: mass%), when the monomer (a) is the main component, It is preferable that it is 50-99, More preferably, it is 55-95, More preferably, it is 60-90, Most preferably, it is 65-85. Moreover, when monomer (b) is a main component, it is preferable that it is 0.5-50, More preferably, it is 1-45, More preferably, it is 2-40, More preferably, it is 3-35, Especially preferably, it is 4-30, Most preferably, it is 5-25.

The polymerization reaction is performed in the presence of the above-described thiol-modified monomer. By using the monomer, a polyalkylene glycol chain (1) (the above general formula (3) is contained in the polymer. (The portion represented by-(AO) _m- ).

  Here, the relationship between the amount of the polyalkylene glycol chain (1) and the amounts used of the monomer (a), the monomer (b) and the monomer (c) is (monomer (a) + When expressed as a ratio (unit: mass%) of the polyalkylene glycol chain (1) when the sum of monomer (b) + monomer (c) is 100%, monomer (a) is the main component. When it is a component, it is preferably 50 to 99, more preferably 55 to 95, still more preferably 60 to 90, and particularly preferably 65 to 85. Moreover, when monomer (b) is a main component, it is preferable that it is 0.5-50, More preferably, it is 1-45, More preferably, it is 2-40, More preferably, it is 3-35, Especially preferably, it is 4-30, Most preferably, it is 5-25.

  By using the thiol-modified monomer in the polymerization reaction, generated by radicals generated from thiol groups (mercapto groups) using heat, light, radiation, etc., or separately used polymerization initiators as needed The resulting radical is chain-transferred to the thiol group, or the disulfide bond is cleaved, and the monomer is successively introduced via one or both ends of the polyalkylene glycol chain (1) comprising the oxyalkylene group via a sulfur atom. Addition will form a polymer.

  In this case, a structural unit having a carboxyl group derived from the monomer (a) via a sulfur atom at one or both ends of a polyalkylene glycol chain (1) comprising m oxyalkylene groups, and a single amount A structural unit having a polyalkylene glycol chain (2) composed of p oxyalkylene groups derived from the body (b) and a structural unit derived from the monomer (c) when the monomer (c) is used. Are mainly produced. In addition, a polymer in which the structure of the polymer is repeated twice or more, a structural unit having a carboxyl group derived from the monomer (a), and p number of units derived from the monomer (b) A polymer having a structural unit having a polyalkylene glycol chain (2) composed of an oxyalkylene group and a structural unit derived from the monomer (c) when the monomer (c) is used is secondary. To generate. Furthermore, a polymer of monomer (a) and monomer (b), or a polymer of monomer (a), monomer (b) and monomer (c) may be produced. is there.

  In the polymerization reaction, in addition to the thiol-modified monomer, a commonly used radical polymerization initiator may be used in combination. Any known radical polymerization initiator can be used as the radical polymerization initiator.

  The amount of the polymerization initiator used may be appropriately adjusted according to the type and amount of the thiol-modified monomer, and is not particularly limited, but considering the balance between the polymerization rate and the yield of the block polymer The amount of the radical polymerization initiator used is preferably 0.001 mol% or more, more preferably 0.01 mol% or more, still more preferably 0.1 mol% with respect to 100 mol% of the unsaturated monomer component. As described above, it is preferably 0.2 mol% or more, preferably 10 mol% or less, more preferably 5 mol% or less, still more preferably 2 mol% or less, and particularly preferably 1 mol% or less.

  In the above polymerization reaction, when solution polymerization is performed using water as a solvent, it is not necessary to remove insoluble components after the polymerization, and therefore it is preferable to use a water-soluble radical polymerization initiator.

  For example, persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate; hydrogen peroxide; azoamidine compounds such as 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [ Cyclic azoamidine compounds such as 2- (2-imidazolin-2-yl) propane] dihydrochloride, azonitrile compounds such as 2- (carbamoylazo) isobutyronitrile, 2,4′-azobis {2-methyl-N— Water-soluble azo initiation such as azoamide compounds such as [2- (1-hydroxybutyl)] propionamide}, macroazo compounds such as esters of 4,4′-azobis (4-cyanovaleric acid) and (alkoxy) polyethylene glycol Agents; etc. are used. These polymerization initiators may be used alone or in combination of two or more. Of these polymerization initiators, water-soluble azo initiators that easily generate radicals from mercapto groups or disulfide bonds are preferred.

  At this time, Fe (II) salt such as alkali metal sulfite such as sodium hydrogen sulfite, metabisulfite, sodium hypophosphite, and molle salt, sodium hydroxymethanesulfinate dihydrate, hydroxylamine hydrochloride, thio An accelerator (reducing agent) such as urea, L-ascorbic acid or a salt thereof, erythorbic acid or a salt or ester thereof may be used in combination. These accelerators (reducing agents) may be used alone or in combination of two or more. In particular, a combination of hydrogen peroxide and an organic reducing agent is preferable. As the organic reducing agent, L-ascorbic acid or a salt thereof, L-ascorbic acid ester, erythorbic acid or a salt thereof, erythorbic acid ester, or the like is preferable. is there. The amount of the accelerator (reducing agent) used is not particularly limited. For example, it is preferably 10 mol% or more, more preferably 20 mol%, relative to 100 mol% of the polymerization initiator used in combination. More preferably, it is 50 mol% or more, preferably 1000 mol% or less, more preferably 500 mol% or less, and still more preferably 400 mol% or less.

  In the above polymerization reaction, when performing solution polymerization using a lower alcohol, aromatic or aliphatic hydrocarbon, ester or ketone as a solvent, or when performing bulk polymerization, benzoyl peroxide, lauroyl peroxide Peroxides such as oxide and sodium peroxide; hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide; azonitrile compounds such as azobisisobutyronitrile; 2,2′-azobis (N-butyl-2- Azoamide compounds such as methylpropionamide), cyclic azoamidine compounds such as 2,2′-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 4,4′-azobis (4-cyanovaleric acid) ) Compounds such as 4,4′-azobis (4-cyanovaleric acid) and (alkoxy) ) Macroazo compound such esters of polyethylene glycol; and the like are used as a radical polymerization initiator. These polymerization initiators may be used alone or in combination of two or more. Of these polymerization initiators, azo initiators that easily generate radicals from mercapto groups or disulfide bonds are preferred.

  In this case, an accelerator such as an amine compound can be used in combination. The amount of the accelerator used is not particularly limited. For example, it is preferably 10 mol% or more, more preferably 20 mol% or more, further preferably 100 mol% of the polymerization initiator used in combination. It is 50 mol% or more, preferably 1000 mol% or less, more preferably 500 mol% or less, and still more preferably 400 mol% or less.

  In the polymerization reaction, when a mixed solvent of water and a lower alcohol is used, it can be appropriately selected from the radical polymerization initiator or a combination of the radical polymerization initiator and an accelerator.

  In addition to the thiol-modified monomer, a chain transfer agent may be used in combination for the polymerization reaction. Examples of chain transfer agents that can be used include thiol chain transfer agents such as mercaptoethanol, thioglycerol, thioglycolic acid, 3-mercaptopropionic acid, thiomalic acid, and 2-mercaptoethanesulfonic acid; secondary such as isopropyl alcohol Alcohol; phosphorous acid, hypophosphorous acid and salts thereof (sodium hypophosphite, potassium hypophosphite, etc.), sulfurous acid, hydrogen sulfite, dithionite, metabisulfite and salts thereof (sodium sulfite, hydrogen sulfite) Sodium, sodium dithionite, sodium metabisulfite, etc.) and the like; and commonly used hydrophilic chain transfer agents such as salts thereof.

  A hydrophobic chain transfer agent can also be used as the chain transfer agent. Hydrophobic chain transfer agents include butanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, cyclohexyl mercaptan, thiophenol, octyl thioglycolate, octyl 3-mercaptopropionate, etc. It is preferable to use a thiol chain transfer agent having a hydrocarbon group.

  In addition, 1 type (s) or 2 or more types can be used as said chain transfer agent, and you may use combining a hydrophilic chain transfer agent and a hydrophobic chain transfer agent.

  The amount of the chain transfer agent used may be appropriately adjusted according to the type and amount of the thiol-modified monomer, and is not particularly limited, but the total number of moles of unsaturated monomer components is 100 mol%. Is preferably 0.1 mol% or more, more preferably 0.25 mol% or more, still more preferably 0.5 mol% or more, and preferably 20 mol% or less, more preferably 15 mol%. Hereinafter, it is more preferably 10 mol% or less.

  The polymerization reaction can be performed by a method such as solution polymerization or bulk polymerization. The solution polymerization can be performed batchwise, continuously, or a combination of two or more thereof. Examples of the solvent used as necessary during the polymerization include water; alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; aromatics such as benzene, toluene, xylene, cyclohexane, and n-hexane; Aliphatic hydrocarbons; Esters such as ethyl acetate; Ketones such as acetone and methyl ethyl ketone; Cyclic ethers such as tetrahydrofuran and dioxane; These may be used alone or in combination of two or more.

  In the above polymerization reaction, the polymerization temperature may be appropriately set according to the type of solvent and polymerization initiator used, and is not particularly limited, but is preferably 0 ° C. or higher, more preferably 30 ° C. or higher, and further Preferably it is 50 degreeC or more, More preferably, it is 70 degreeC or more, Preferably it is 150 degrees C or less, More preferably, it is 120 degrees C or less, More preferably, it is 100 degrees C or less, More preferably, it is 90 degrees C or less.

  Further, the method for adding the unsaturated monomer component to the reaction vessel is not particularly limited. For example, a method in which the entire amount is initially charged into the reaction vessel at once; a method in which the entire amount is divided or continuously charged into the reaction vessel; The method may be any of the methods of initially charging the reaction vessel and dividing or continuously charging the remainder into the reaction vessel. Moreover, the radical polymerization initiator and the chain transfer agent may be charged into the reaction vessel from the beginning, may be dropped into the reaction vessel, or may be combined in accordance with the purpose.

  In the above polymerization reaction, in order to obtain a copolymer having a predetermined molecular weight with good reproducibility, it is necessary to allow the polymerization reaction to proceed stably. Therefore, in the case of solution polymerization, the solvent used is dissolved at 25 ° C. The oxygen concentration is preferably in the range of 5 ppm or less. More preferably, it is 4 ppm or less, More preferably, it is 2 ppm or less, Most preferably, it is 1 ppm or less. In addition, when nitrogen substitution etc. are performed after adding a monomer to a solvent, it is preferable to make the dissolved oxygen concentration of the system | strain containing a monomer into the said range.

  The adjustment of the dissolved oxygen concentration of the solvent may be performed in a polymerization reaction tank, or a solution in which the amount of dissolved oxygen is adjusted in advance may be used. For example, the following (1) ) To (5).

(1) After pressure-filling an inert gas such as nitrogen in a sealed container containing a solvent, the partial pressure of oxygen in the solvent is lowered by lowering the pressure in the sealed container. Under nitrogen flow, the pressure in the sealed container may be reduced;
(2) Stir the liquid phase portion vigorously for a long time while replacing the gas phase portion in the container containing the solvent with an inert gas such as nitrogen;
(3) Bubbling an inert gas such as nitrogen for a long time in the solvent placed in the container;
(4) The solvent is once boiled and then cooled in an inert gas atmosphere such as nitrogen;
(5) A static mixer (static mixer) is installed in the middle of the pipe, and an inert gas such as nitrogen is mixed in the pipe for transferring the solvent to the polymerization reaction tank.

  The polymer obtained by the above polymerization reaction is preferably adjusted to a pH range of weak acid or higher in an aqueous solution state from the viewpoint of handleability. More preferably, the pH is 4 or more, further preferably 5 or more, and particularly preferably 6 or more. On the other hand, the polymerization reaction may be carried out at a pH of 7 or more. In this case, however, the polymerization rate is lowered, and at the same time, the polymerizability is not sufficient and the dispersion performance is lowered. It is preferable to perform a polymerization reaction. More preferably, it is less than pH 6, More preferably, it is less than pH 5.5, Most preferably, it is less than pH 5. Thus, preferable polymerization initiators that cause the polymerization system to have a pH of 7.0 or less include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, and azoamidine compounds such as azobis-2-methylpropionamidine hydrochloride. It is preferable to use a water-soluble azo initiator, hydrogen peroxide, or a combination of hydrogen peroxide and an organic reducing agent.

  Therefore, it is preferable to adjust to a higher pH by adding an alkaline substance after the polymerization reaction at a low pH.

  As a preferred embodiment, specifically, a method of adjusting the pH to 6 or more by adding an alkali after carrying out a copolymerization reaction at a pH of less than 6; adding an alkali after carrying out a copolymerization reaction at a pH of less than 5 to give a pH of 5 or more And a method of adjusting the pH to 6 or more by adding an alkali after carrying out a copolymerization reaction at a pH of less than 5. The pH can be adjusted using, for example, an inorganic salt such as a monovalent metal or divalent metal hydroxide or carbonate; ammonia; an alkali such as an organic amine. When pH needs to be lowered, particularly when pH adjustment is required during polymerization, for example, phosphoric acid, sulfuric acid, nitric acid, alkyl phosphoric acid, alkyl sulfuric acid, alkylsulfonic acid, (alkyl) benzenesulfone The pH can be adjusted using an acidic substance such as an acid, and among these acidic substances, phosphoric acid is preferred from the viewpoint of having a pH buffering action. Further, after the reaction is completed, the concentration can be adjusted if necessary.

  The polymer obtained by the above polymerization reaction may be subjected to a process of isolating individual polymers as necessary, but from the viewpoint of work efficiency, production cost, etc., individual polymers are isolated. For example, it can be used for various applications such as a dispersant (particularly a cement admixture).

  A dispersant containing the polyalkylene glycol chain-containing thiol polymer (hereinafter also referred to as “polymer component”) is also one aspect of the present invention. A cement admixture containing the thiol-modified monomer (hereinafter also referred to as “monomer component”) and / or the polyalkylene glycol chain-containing thiol polymer is also one aspect of the present invention.

  Hereinafter, a cement admixture will be described as a typical dispersant.

  The blending amount of the polymer component in the cement admixture may be appropriately adjusted according to the desired dispersion performance, and is not particularly limited. Specifically, the cement admixture in terms of solid content is used. It is suitable that it is 50 mass% or more with respect to the total mass of 100 mass%. More preferably, it is 60 mass% or more, More preferably, it is 70 mass% or more, Most preferably, it is 80 mass% or more.

  If necessary, the cement admixture may contain a polycarboxylic acid polymer in addition to the polymer component. In this case, the blending amount is preferably a ratio of polymer component / polycarboxylic acid polymer (unit: mass%), and is 90/10 to 10/90. More preferably, it is 80 / 20-20 / 80, More preferably, it is 70 / 30-30 / 70, Most preferably, it is 60 / 40-40 / 60.

  Further, when the cement admixture contains a monomer component, the content of the monomer component is, for example, 50% by mass or more with respect to 100% by mass of the total mass of the cement admixture in terms of solid content. Is preferred. More preferably, it is 60 mass% or more, More preferably, it is 70 mass% or more, Most preferably, it is 80 mass% or more.

  Also in this case, a polycarboxylic acid polymer may be blended. At that time, the blending amount is preferably a ratio of monomer component / polycarboxylic acid polymer (unit: mass%) of 90/10 to 10/90. More preferably, it is 80 / 20-20 / 80, More preferably, it is 70 / 30-30 / 70, Most preferably, it is 60 / 40-40 / 60.

  In addition, when the cement admixture includes the polymer component and the monomer component, the content is preferably in the above-described range as the total amount of the monomer component and the polymer component, The blending amount with the polycarboxylic acid polymer is also preferably within the above-mentioned range as the total amount of the monomer component and the polymer component.

  In the cement admixture of the present invention, an antifoaming agent (such as (poly) oxyethylene (poly) oxypropylene adduct or diethylene glycol heptyl ether) or a polyalkyleneimine (such as ethyleneimine or propyleneimine) is optionally used. Polyalkyleneimine alkylene oxide adducts such as can be blended.

  As the cement admixture, one or more conventionally known cement additives can be used in combination. The conventionally known cement admixture is preferably a conventionally known polycarboxylic acid admixture and a sulfonic acid admixture having a sulfonic acid group in the molecule. When these conventionally known cement admixtures are used in combination, a cement admixture that exhibits stable dispersion performance regardless of the brand or lot number of the cement is obtained.

  The sulfonic acid-based admixture is an admixture that exhibits dispersibility to cement due to electrostatic repulsion mainly caused by sulfonic acid groups, and various conventionally known sulfonic acid-based admixtures can be used. A compound having an aromatic group in the molecule is preferred. For example, polyalkylaryl sulfonate system such as naphthalene sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate, anthracene sulfonic acid formaldehyde condensate; melamine formalin resin sulfonate system such as melamine sulfonic acid formaldehyde condensate; amino Aromatic aminosulfonates such as aryl sulfonic acid-phenol-formaldehyde condensates; lignin sulfonates such as lignin sulfonates and modified lignin sulfonates; various sulfonic acid admixtures such as polystyrene sulfonates Is mentioned. For concrete with a high water / cement ratio, lignin sulfonate-based admixtures are preferably used, whereas for concrete with a moderate water / cement ratio where higher dispersion performance is required, Admixtures such as polyalkylaryl sulfonates, melamine formalin sulfonates, aromatic amino sulfonates, and polystyrene sulfonates are preferably used. In addition, the sulfonic acid type admixture having a sulfonic acid group in the molecule may be used alone or in combination of two or more.

  As the cement admixture of the present invention, an oxycarboxylic acid compound can be used in combination with the above sulfonic acid admixture. By containing the oxycarboxylic acid-based compound, higher dispersion retention performance can be exhibited even in a high-temperature environment.

  As said oxycarboxylic acid type compound, C4-C10 oxycarboxylic acid or its salt is preferable, and it is preferable to use gluconic acid or its salt as an oxycarboxylic acid type compound.

  The cement admixture of the present invention may be used in combination with conventionally known cement additives (materials) as exemplified in the following (1) to (10) as necessary.

(1) Water-soluble polymeric substances (2) Polymer emulsions (3) Early strengthening agents / accelerators (4) Antifoaming agents other than oxyalkylenes (5) AE agents (6) Other surfactants (7) Waterproofing Agent (8) Rust preventive agent (9) Crack reducing agent (10) Expansion material.

  Other conventionally known cement additives (materials) include cement wetting agents, thickeners, separation reducing agents, flocculants, drying shrinkage reducing agents, strength enhancers, self-leveling agents, rust preventives, colorants, anti-corrosion agents. A mold agent etc. can be mentioned. These conventionally known cement additives (materials) may be used alone or in combination of two or more.

  The cement admixture of the present invention may be used in the form of an aqueous solution, or after reaction, neutralized with a divalent metal hydroxide such as calcium or magnesium to obtain a polyvalent metal salt and then dried. , Supported on inorganic powder such as silica-based fine powder and dried, or dried and solidified into a thin film on a support using a drum-type drying device, a disk-type drying device or a belt-type drying device, and then pulverized Alternatively, it may be used after being powdered by drying and solidifying with a spray dryer. Also, the powdered cement admixture of the present invention is blended in advance into a cement composition not containing water such as cement powder and dry mortar, and used as a premix product for plastering, floor finishing, grout, etc. Alternatively, it may be blended when the cement composition is kneaded.

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

  Among the hydraulic compositions, a cement composition that uses cement as a hydraulic material is the most common, and the cement composition contains the cement admixture of the present invention, cement, and water as essential components. Such a cement composition is also one aspect of the present invention. That is, a cement composition including cement and the thiol-modified monomer and / or the polyalkylene glycol chain-containing thiol polymer is also one aspect of the present invention.

  In the above-mentioned cement composition, the cement is not particularly limited. For example, Portland cement (ordinary, early strength, very early strength, moderate heat, sulfate-resistant and low alkali types thereof), various mixed cements (blast furnace cement, silica) Cement, fly ash cement), white Portland cement, alumina cement, super fast cement (1 clinker fast cement, 2 clinker fast cement, magnesium phosphate cement), grout cement, oil well cement, low heat cement (low heat type) Manufactured using one or more of blast furnace cement, fly ash mixed low heat generation type blast furnace cement, high belite content cement, ultra high strength cement, cement-based solidified material, eco-cement (city waste incineration ash, sewage sludge incineration ash) Cement), and blast furnace steel Grayed, fly ash, cinder ash, clinker ash, husk ash, silica fume, silica powder, a fine powder and gypsum limestone powder may be added. In addition to gravel, crushed stone, granulated slag, recycled aggregate, etc., the aggregates are siliceous, clay, zircon, high alumina, silicon carbide, graphite, chrome, chromic, magnesia. Refractory aggregate such as can be used.

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

  In the above cement composition, as a blending ratio of the cement admixture of the present invention, for example, when used for mortar or concrete using hydraulic cement, 0.01% by mass or more of the cement mass in terms of solid content, It is preferable to set it as 10.0 mass% or less. As a result, various preferable effects such as reduction in unit water amount, increase in strength, and improvement in durability are brought about. If it is less than 0.01%, the performance may not be sufficient, and if it exceeds 10.0% by mass, the effect of improving dispersibility is substantially saturated, and more than necessary. The use of the cement admixture of the present invention may increase the production cost. More preferably, it is 0.02 mass% or more and 5.0 mass% or less, More preferably, it is 0.05 mass% or more, 3.0 mass% or less, Most preferably, it is 0.1 mass% or more, 2.0 mass% It is as follows.

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

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples, and appropriate modifications are made within the scope that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention. Unless otherwise specified, “%” means “mass% (% by weight)”, and “−” in the table indicates that measurement / analysis is not performed or the indicated component is used. It means not.

<Manufacture of thiol-modified monomers>
(Production Example 1)
(1) Esterification step 500 mL glass equipped with a moisture determination receiver with a Liebig condenser connected to a vacuum pump, an agitator with a Teflon (registered trademark) stirring blade and an agitation seal, and a temperature sensor with a glass protective tube A predetermined amount of polyalkylene glycol (hereinafter also referred to as “PAG”), a mercaptocarboxylic acid, an acid catalyst for esterification, and an antioxidant were charged in the reactor. While stirring the reaction system, the temperature is gradually raised and the pressure is reduced, and water generated in the esterification reaction is distilled out of the reaction system as a water / mercaptocarboxylic acid azeotrope while the reaction system is heated to a predetermined temperature. Then, the esterification reaction was carried out for a predetermined time while maintaining the pressure condition. Subsequently, the remaining mercaptocarboxylic acid was further distilled off under reduced pressure to obtain a product.

(2) Neutralization step and water dilution step After completion of the esterification step, the pressure of the reaction system is returned to normal pressure and allowed to cool to 60 ° C or lower with stirring so as not to solidify. The neutralization process for neutralizing and the water dilution process were performed, and the aqueous solution of the thiol modified monomer was obtained.

(Production Example 2)
(1) Esterification Step In a 500 mL glass reactor equipped with a water quantitative receiver with a Jimroth condenser, a stirrer with Teflon (registered trademark) and a stirrer with a stirring seal, and a temperature sensor with a glass protective tube, Predetermined amounts of polyalkylene glycol, mercaptocarboxylic acid, acid catalyst for esterification, antioxidant and dehydrating solvent were charged. After filling the moisture meter with a dehydrated solvent, the reaction system was heated to reflux while stirring. The esterification reaction was carried out for a predetermined time while adding a dehydrating solvent in the middle so that the temperature in the reaction system became a predetermined temperature.

(2) Solvent removal step After completion of the esterification step, the pressure inside the reactor was gradually reduced while maintaining a predetermined temperature, and the dehydrating solvent and the remaining mercaptocarboxylic acid were distilled off under a predetermined pressure condition.

(3) Neutralization step and water dilution step After completion of the above solvent removal step, the pressure of the reaction system is returned to normal pressure, and the mixture is allowed to cool to 60 ° C. or lower with stirring so as not to solidify. The neutralization process for neutralizing and the water dilution process were performed, and the aqueous solution of the thiol modified monomer was obtained.

(Comparative Production Method Example 1)
(1) Esterification step In a 500 mL glass reactor equipped with a moisture meter with a Jimroth condenser, a stirrer with Teflon (registered trademark) and a stirrer with a stirring seal, and a temperature sensor with a glass protective tube, A predetermined amount of polyalkylene glycol, mercaptocarboxylic acid, acid catalyst for esterification, antioxidant, and dehydrating solvent (cyclohexane) were charged. After filling the moisture meter with a dehydrated solvent, the reaction system was heated to reflux while stirring. The esterification reaction was carried out for a predetermined time while adding a dehydrating solvent in the middle so that the temperature in the reaction system became a predetermined temperature.

(2) Neutralization step and water dilution step After the completion of the esterification step, the mixture is allowed to cool to 60 ° C. or lower with stirring so as not to solidify, and then neutralized for neutralizing the acid catalyst for esterification, and A water dilution step was performed.

(3) Solvent removal step After completion of the neutralization step and the water dilution step, the reaction system is heated to about 70 ° C, and after the reflux has settled, it is gradually heated to about 100 ° C to distill off the cyclohexane. did. Heating was stopped, nitrogen was bubbled at 30 mL / min for 90 minutes while cooling, and the remaining cyclohexane was removed to obtain an aqueous solution of a thiol-modified monomer.

(Comparative production method example 2)
(1) Esterification step 500 mL glass equipped with a moisture determination receiver with a Liebig condenser connected to a vacuum pump, an agitator with a Teflon (registered trademark) stirring blade and an agitation seal, and a temperature sensor with a glass protective tube Predetermined amounts of polyalkylene glycol, mercaptocarboxylic acid, and antioxidant were charged into the reactor. While stirring the reaction system, the temperature is gradually raised and the pressure is reduced, and water generated in the esterification reaction is distilled out of the reaction system as a water / mercaptocarboxylic acid azeotrope while the reaction system is heated to a predetermined temperature. The esterification reaction was carried out for a predetermined time while maintaining the pressure condition. Subsequently, the remaining mercaptocarboxylic acid was further distilled off under reduced pressure to obtain a product.

(2) Water dilution step After completion of the reaction, the pressure of the reaction system is returned to normal pressure, and allowed to cool to 60 ° C. or lower with stirring so as not to solidify. Obtained.

(Examples 1-6 and Comparative Examples 1-3)
A thiol-modified monomer was produced by employing the above-mentioned production method 1 or production method 2 or comparative production method example 1 or comparative production method example 2 using the raw materials, reaction conditions and production steps shown in Table 1 below.

<GPC analysis method>
Here, the PAG used as a raw material was analyzed for the number average molecular weight (Mn) under the following conditions, and from this Mn, the average added mole number (AO repeating unit number; m) of the oxyalkylene group (AO) in the PAG was calculated. Calculated. In addition, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polymers and comparative polymers obtained in the production examples and comparative production examples described later were also analyzed under the following conditions.

Apparatus: Waters Alliance (2695);
Analysis software: Waters, Empower Professional + GPC option;
Column used: manufactured by Tosoh Corporation, TSK guard column SWXL + TSKgel G4000SWXL + G3000SWXL + G2000SWXL;
Detector: differential refractometer (RI) detector (Waters 2414), multi-wavelength visible ultraviolet (PDA) detector (Waters 2996);
Eluent: A 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 further adjusting the pH to 6.0 with acetic acid was used;
Reference material for calibration curve: polyethylene glycol (peak top molecular weight (Mp) 272500, 219300, 107000, 50000, 24000, 12600, 7100, 4250, 1470);
Calibration curve: created by a cubic equation based on the Mp value and elution time of the polyethylene glycol;
Flow rate: 1.0 mL / min;
Column temperature: 40 ° C .;
Measurement time: 45 minutes;
Sample solution injection amount: 100 μL (PAG, thiol-modified monomer is an eluent solution having a sample concentration of 0.4% by mass, and polymer is a sample concentration of 0.5% by mass).

<GPC analysis condition 1 (analysis of PAG)>
In the RI chromatogram, the flat and stable portions in the baseline immediately before and after elution were connected with straight lines, and peaks were detected and analyzed. When a multimer or an impurity was measured partially overlapping the target peak, the molecular weight of the target product was measured by vertically dividing at the most concave portion of the overlapping portion of the peak. As described above, the average number of added moles (number of repeating units; m) of alkylene oxide (AO) was calculated from the value of Mn.

  For each of the thiol-modified monomers (PEG-SH (1) to PEG-SH (9)) obtained in Examples 1 to 6 and Comparative Examples 1 to 3, total esterification in the product was performed by the following method. Rate (% by weight), diester / total ester ratio (% by weight) in the product (from liquid chromatography analysis (LC)), and the abundance ratio of monomeric and multimeric components in the product (mass) %) (By gel permeation chromatography (GPC)). The results are shown in Table 2 below.

<LC analysis method>
Here, an example of the analysis method by LC is shown. However, depending on the structure of the thiol-modified monomer, there are those that cannot be analyzed under these conditions. In that case, the analysis was performed by appropriately changing the conditions such as the LC column and the eluent.

Apparatus: Waters Alliance (2695);
Analysis software: Emper Professional + GPC option from Waters;
Column: GL Science Inertsil ODS-2 guard column + column (inner diameter 4.6 mm × 250 mm × 3);
Detector: differential refractometer (RI) detector (Waters 2414), multi-wavelength visible ultraviolet (PDA) detector (Waters 2996);
Eluent: A solution adjusted to pH 4.0 by adding 30% NaOH aqueous solution to a mixture of acetonitrile / 100 mM acetate ion exchange aqueous solution = 40/60 (mass%);
Flow rate: 0.6 mL / min;
Column temperature: 40 ° C .;
Measurement time: 90 minutes;
Sample solution injection amount: 100 μL (eluent solution having a sample concentration of 1% by mass).

<LC analysis conditions: Analysis of thiol-modified monomer>
(Calculation of total esterification rate)
From the ratio of the peak area by the RI detector, the calculation was performed as follows.

Total esterification rate = (monoester peak area + diester peak area) / (raw material PAG area + monoester peak area + diester peak area)
(Calculation of diester / total ester ratio)
From the ratio of the peak area by the RI detector, the calculation was performed as follows.

Diester / total ester ratio = (diester peak area) / (monoester peak area + diester peak area)
Here, the monoester is a monothiol-modified monomer, and the diester is a dithiol-modified product.

<< Production of polyalkylene glycol chain-containing thiol polymer >>
(Production Examples 1 to 8 and Comparative Production Examples 1 to 4)
Next, using the thiol-modified monomers (PEG-SH (1) to PEG-SH (9)) obtained in Examples 1 to 6 and Comparative Examples 1 to 3, an unsaturated carboxylic acid-based monomer (Meth) acrylic acid as a body and polyalkylene ethylene glycol monomer (hereinafter also referred to as “PEG monomer”) as an unsaturated (poly) alkylene glycol monomer are polymerized to form a polyalkylene glycol chain A containing thiol polymer was produced.

  Specifically, first, a predetermined amount of monomer (including the thiol-modified monomer aqueous solution obtained above) was mixed to prepare a monomer aqueous solution. On the other hand, a predetermined amount of an aqueous initiator solution was prepared.

  Next, a predetermined amount of water was charged into a glass reactor equipped with a Dimroth cooling pipe, a Teflon (registered trademark) stirring blade and a stirrer with a stirring seal, a nitrogen gas introduction pipe, and a temperature sensor, and stirred at 250 rpm. The mixture was heated to a predetermined temperature while introducing nitrogen gas at 100 to 200 mL / min. Subsequently, a predetermined amount of the monomer aqueous solution and the initiator aqueous solution were dropped into the reactor over a predetermined time, and after completion of the dropping, the polymerization reaction was completed by holding at a predetermined temperature for 1 hour. After cooling to room temperature, a 30% aqueous NaOH solution was added to adjust the pH to obtain an aqueous polymer solution.

  The details (composition, polymerization conditions) of each production example and each comparative production example are shown in Table 3 below. The analysis results of the polymers obtained in each production example and each comparative production example are shown in Table 4 below.

≪Evaluation of dispersion performance≫
(Test Examples 1-8 and Comparative Test Examples 1-8)
Next, using the polymers obtained in Production Examples 1 to 8 and Comparative Production Examples 1 to 4 (Polymer (1) to Polymer (12)), dispersion performance was evaluated by the following method. It was.

<Method for evaluating dispersion performance: mortar test>
The mortar test was performed in an environment where the temperature was 20 ° C. ± 1 ° C. and the relative humidity was 60% ± 10%.

The mortar formulation was C / S / W = 550/1350/220 (g). However,
C: Ordinary Portland cement (manufactured by Taiheiyo Cement)
S: Standard sand for cement strength test (Cement Association)
W: An ion exchange aqueous solution of a polymer and an antifoaming agent.

  As W, weigh out the amount of the polymer aqueous solution shown in Table 5 below, add 10% by mass of the antifoaming agent MA-404 (manufactured by Pozoris) to the polymer solid content, and further add ion-exchanged water. In addition, a predetermined amount was obtained and dissolved sufficiently uniformly. The addition amount of the polymer described in Table 5 is the weight percent of the polymer solid content with respect to the cement weight.

  A stainless beater (stirring blade) was attached to a Hobart mortar mixer (model number N-50; manufactured by Hobart), C and W were added, and kneaded at a first speed for 30 seconds. Further, S was added over 30 seconds while kneading at a first speed. After the completion of S addition, after kneading for 30 seconds at the second speed, the mixer was stopped, the mortar was scraped off for 15 seconds, and then allowed to stand for 75 seconds. The mixture was allowed to stand for 75 seconds and then kneaded at a second speed for 60 seconds to prepare a mortar.

  The mortar was transferred from the kneading container to a 1 L polyethylene container and stirred 20 times with a spatula. I struck with a stick, stuffed the mortar into the plate to the full extent of the flow cone, struck it with a stick 15 times, and finally made up the shortage and smoothed the surface of the flow cone. Immediately after that, the flow cone is pulled up vertically, and the diameter of the expanded mortar (the diameter of the longest part (major axis) and the diameter of the part forming 90 degrees with respect to the major axis) is measured at two locations, and the average value is 0 times. The flow value was used. Immediately after measuring the zero stroke flow value, 15 falling motions were given in 15 seconds, and the diameter of the expanded mortar (the diameter of the longest part (major axis) and the diameter of the part forming 90 degrees with respect to the major axis) was 2 The points were measured and the average value was taken as the 15-stroke flow value. Moreover, the amount of mortar air was also measured as needed. The 15-stroke flow value is superior in dispersion performance as the numerical value is larger. Further, when mortar is prepared without a dispersant such as a polymer under these conditions, kneading cannot be performed sufficiently and fluidity does not appear in the mortar. The 0-stroke flow value is around 105 mm, and the 15-stroke flow value is around 145 mm.

<Method of measuring the amount of mortar air>
About 200 mL of mortar was packed in a 500 mL glass graduated cylinder, struck with a round bar having a diameter of 8 mm, and gently bubbled by hand to remove coarse bubbles. Furthermore, about 200 mL of mortar was added and air bubbles were similarly removed. Then, the volume and weight of the mortar were measured, and the amount of air was calculated from the density of each material.

  Table 5 below shows the test results of the dispersion performance for Test Examples 1 to 8 and Comparative Test Examples 1 to 8 using the polymer (1) to the polymer (12).

  From the results shown in Table 5, when compared with the same addition amount, the admixture for concrete containing the polymer synthesized using the thiol-modified monomer produced by the production method according to the present invention is obtained by the conventional method. It can be seen that superior fluidity can be achieved and that the dispersion performance is excellent as compared with a polymer containing a polymer synthesized using the manufactured thiol-modified monomer.

Claims (7)

The following general formula (1):

(Wherein R ¹ and R ² are the same or different and represent an organic residue)
A mercaptocarboxylic acid represented by the following general formula (2):

(In the formula, AO is the same or different and represents one or more oxyalkylene groups having 2 to 18 carbon atoms. M represents the average number of moles of oxyalkylene groups and is an integer of 10 to 500. is there)
Is subjected to an esterification reaction in the presence of an acid catalyst as a dehydration catalyst, and the following general formula (3):

(In the formula, R ¹ and R ² are the same or different and represent an organic residue. AO is the same or different and represents one or more oxyalkylene groups having 2 to 18 carbon atoms. M Represents the average number of moles of the oxyalkylene group and is an integer of 10 to 500)
A process for obtaining a thiol-modified monomer represented by:
The method for producing a thiol-modified monomer, further comprising a step of neutralizing the acid catalyst with an alkali in the absence of a solvent.   The method for producing a thiol-modified monomer according to claim 1, wherein the amount of the alkali used is 0.95 to 1.20 equivalents relative to the acid catalyst.   The method for producing a thiol-modified monomer according to claim 1 or 2, wherein the alkali is an alkali metal hydroxide and / or an alkaline earth metal hydroxide.   An unsaturated carboxylic acid monomer and an unsaturated (poly) alkylene glycol monomer in the presence of the thiol-modified monomer produced by the production method according to any one of claims 1 to 3. A polyalkylene glycol chain-containing thiol polymer obtained by polymerizing an unsaturated monomer component.   A dispersant comprising the polyalkylene glycol chain-containing thiol polymer according to claim 4.   A cement admixture comprising the polyalkylene glycol chain-containing thiol polymer according to claim 4.   A cement composition comprising cement and the cement admixture according to claim 6.