JPH04209613A - Production of water-soluble sulfonate-terminated vinyl copolymer and cement dispersant comprising copolymer produced thereby - Google Patents

Abstract

PURPOSE:To obtain the title copolymer which, when added to a cement, can give thereto high dispersibility and flow little in change with time and can give a cured cement product of low setting retardation by effecting an addition reaction of a specified radical-activated bipolymer with a specified vinyl monomer. CONSTITUTION:The title copolymer is obtained by copolymerizing a vinyl monomer of formula I with a vinyl monomer of formula II in a molar ratio of 50/50 to 95/5 in the presence of a radical initiator, conducting free radical termination to obtain a bipolymer, adding a radical initiator to this bipolymer to form a radical-activated bipolymer, and effecting a radical addition reaction of this bipolymer with a vinyl monomer of formula III. In the above formulas; R<1> to R<5> and R<7> are each H or CH3; R<6> is 1-3C alkyl; X and Y are each an alkali metal, an alkaline earth metal, ammonium or an organic amine; and (n) is 5-25. By adding this bipolymer as a cement dispersant to a cement composition, it is possible to impart excellent flow which little changes with time thereto and to give a cured cement product of a desired strength and low setting retardation.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a method for producing a water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain, and a method for producing a water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain obtained by the production method. The present invention relates to a cement dispersant comprising a water-soluble vinyl copolymer having a group-containing water-soluble vinyl copolymer.

Concrete is made by mixing cement, gravel, sand, etc. with water.
Mortar is made by kneading cement, sand, etc. with water and hardening it through the hydration reaction of the cement. At this time, a dispersant is often used as an auxiliary agent. By improving the dispersion and flow of particles, it improves workability, promotes the hydration reaction of cement, brings about a water reduction effect, and as a result improves the strength of concrete, etc. Therefore, the properties of the cement dispersant are: 1) the dispersion fluidity of cement particles is large; 2) the dispersion fluidity changes little over time (less slump loss); and 3) it leads to a decrease in the strength of the hardened product. 4) Avoid causing excessive entrended air; 4) Reduce the negative effects of condensation delay; 5)
) Requires characteristics such as good economic efficiency.

The present invention meets the above requirements.

<Prior art and its problems> There have been various proposals for using water-soluble vinyl copolymers as cement dispersants (Japanese Patent Publication No. 59-18338, Japanese Patent Publication No. 2-7901, Japanese Patent Publication No. 2-8983, No. 1999 -22
6757).

As in these conventional proposals, water-soluble vinyl copolymers are usually produced by copolymerizing different vinyl monomers in an aqueous system.

By the way, in order for the water-soluble vinyl copolymer to exhibit sufficient performance when used as a cement dispersant, the water-soluble vinyl copolymer must have an appropriate molecular weight, It is also important to have an appropriate proportion of polar groups that are adsorbed onto cement particles and provide a dispersion flow effect.

Therefore, in the above conventional proposal, various copolymerization ratios of the vinyl monomers used are selected in order to obtain a vinyl copolymer in which vinyl monomers having polar groups are copolymerized at a predetermined ratio. It is.

However, when a water-soluble vinyl copolymer is produced by such a method, it is difficult to obtain a water-soluble vinyl copolymer with a controlled structure in which a specific polar group is introduced only at the end of the main chain of the copolymer. However, there is a problem in that a vinyl monomer having a polar group becomes a water-soluble vinyl copolymer in which runs and dams are bonded. When used as a cement dispersant, a water-soluble vinyl copolymer in which vinyl monomers having polar groups are randomly bonded has the effect of improving the dispersibility of cement immediately after cross-contact and the fluidity of the resulting cement composition. However, the fluidity decreases significantly over time (slump loss is large), which significantly reduces workability in on-site construction of concrete, mortar, etc. Furthermore, if the amount added is increased in order to reduce the slump loss, the setting delay will increase, making it impossible to obtain a hardened cement product with the desired strength.

<Problems to be Solved by the Invention and Means for Solving the Problems> The present invention solves the conventional problems such as those on boards and meets the above-mentioned demands. The present invention provides a method for producing a water-soluble vinyl copolymer and a cement dispersant comprising the water-soluble vinyl copolymer obtained by the method.

As a result of intensive research from the above viewpoint, the present inventors have discovered that a water-soluble vinyl copolymer with a controlled structure having a sulfonic acid group as a polar group at the end of the main chain can be obtained by a specific method, and that The present inventors have discovered that a water-soluble vinyl copolymer is excellent in that it has various properties required as a cement dispersant, and has completed the present invention.

That is, the present invention.

A vinyl monomer represented by the following formula (1) and a vinyl monomer represented by the following formula (2) are combined into a vinyl monomer represented by the formula (1)/a vinyl monomer represented by the formula (2). = 50750
After copolymerizing in the presence of a radical initiator at a ratio of ~9515 (molar ratio), the radicals are terminated to obtain a binary copolymer, and then a radical initiator is added to the binary copolymer to generate a radical After forming an activated binary copolymer, radically adding one or more vinyl monomers represented by the following formula (3) to the radically activated binary copolymer. A method for producing a water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain, characterized by It relates to a dispersant.

Formula (1): % Formula % Formula (2) Near ■ CH2-C-CH2S03 Y [In formulas (1) to (3), R1 to R'l and R7 are the same or different, H or CH3.

R6 is an alkyl group having 1 to 3 carbon atoms.

X and Y are alkali metals, alkaline earth metals, ammonium or organic amines.

n is an integer of 5 to 25.] The manufacturing method according to the present invention includes a first step, a second step, and a third step.
It is broadly divided into processes.

The first step is to radically copolymerize the vinyl monomer represented by the above formula (1) and the vinyl monomer represented by the above formula (2) at a predetermined ratio, and then radical termination is performed to obtain 1 Formula (1
) and a vinyl monomer represented by formula (2).

Examples of the vinyl monomer represented by formula (1) include alkali metal salts, alkaline earth metal salts, and alkanolamine salts of acrylic acid, methacrylic acid, and crotonic acid. Furthermore, as the vinyl monomer represented by formula (2), one terminal end-blocked alkyl group such as methoxypolyethylene glycol, ethoxypolyethylene glycol, propoxypolyethylene glycol, impropoxypolyethylene glycol, methoxypolyethylenepolypropylene glycol or ethoxypolyethylene polypropylene glycol is used. There is an esterified product of polyalkylene glycol and acrylic acid, methacrylic acid, or crotonic acid, in which the number of added moles of polyalkylene glycol is 5 to 25.

In the first step of the production method according to the present invention, 1 vinyl monomer represented by formula (1)/vinyl monomer represented by formula (2)=
50750-9515 (molar ratio), preferably 55/
Both are copolymerized at a ratio of 45 to 85/15 (molar ratio). This is to ensure that when the finally obtained water-soluble vinyl copolymer is used as a cement dispersant, the water-soluble vinyl copolymer sufficiently exhibits various performances required as a cement dispersant.

The copolymerization reaction between the vinyl monomer represented by formula (1) and the vinyl monomer represented by formula (2) is as follows.

Although the method is not particularly limited, it is preferable to carry out aqueous solution polymerization using water or a mixed solvent of water and a water-soluble organic solvent. The type of initiator is not limited as long as it decomposes under temperature to generate radicals, but it is advantageous to use a water-soluble radical initiator.

As such a water-soluble radical initiator, the typical value is 1 tll.
Examples include persulfates such as ammonium dipersulfate, hydrogen peroxide, and 2.2°-asobis(2-amidinopropane) dihydrochloride. These can also be used as redox catalysts in combination with reducing substances such as sulfites and L-ascorbic acid, as well as amines and the like. Also, ceric ammonium nitrate, ceric ammonium sulfate, etc.
) A ceric salt catalyst may be used as a strong oxidizing agent.

The optimal usage amount of these water-soluble radical initiators varies depending on the water-soluble radical initiator and the type of vinyl monomer used for copolymerization, but for example, when using ammonium persulfate, the amount shown by formula (1) is It is preferably in the range of 0.2 to 3% by weight based on the total amount of the vinyl monomer and the vinyl monomer represented by formula (2).

The first step of the production method according to the present invention is to timely terminate the radicals of the reaction system in the radical copolymerization of the two types of vinyl monomers described above to obtain a binary copolymer. There are roughly two types of methods for stopping such radicals.

The first method is to continue the reaction until the radicals completely disappear from the reaction system and the radical copolymerization reaction substantially stops. The second method is to add to the reaction system a radical terminator that forcibly decomposes and eliminates radicals.

Conventionally known compounds can be used as such radical terminators. Radical terminators that can be advantageously used include 3-mercap)-1,2-propanediol, dithioerythritol, 2-mercaptoethanol, 1,
There are compounds such as 2-ethanedithiol that have at least two active hydrogen groups such as hydroxyl groups or thiol groups in the molecule. Other radical terminators that can be advantageously used include:
There are compounds that share a thiol group and an α, β-, β-hydrocarbon group in the molecule. More specifically, such compounds include α,β-unsaturated monocarboxylic acid solcaptoalkyl esters such as mercaptoethyl (meth)acrylate and mercaptoethyl crotonic acid ester.

1. Two types of radical terminators, that is, compounds containing at least two active hydrogen groups such as hydroxyl groups or thiol groups in the molecule, and compounds that share a thiol group and α, β-, β-hydrocarbon groups in the molecule. The advantage of adding a compound to the copolymerization reaction system is that it can provide radical active sites at the ends of the resulting binary copolymer when a radical initiator is added in the second step reaction, which will be described later. The advantage is that the radical addition of the vinyl monomer represented by formula (3) in the subsequent third step, which will be described later, can be carried out efficiently and selectively.

In the first step of the production method according to the present invention, the purpose of adding a radical terminator to the copolymerization reaction system is originally to stop the copolymerization reaction, but it also adds a radical terminator to the copolymerization reaction system. The point is that the molecular weight can be adjusted. In this sense, the radical terminator can be added at any point in the copolymerization reaction, either in batches or in portions; however, in the present invention, in addition to the radical terminator, for the purpose of controlling the molecular weight, There is no restriction on the use of known chain transfer agents such as mercaptoacetic acid. The optimum amount of the radical terminating agent to be added is determined by the molecular weight of the binary copolymer, the vinyl monomer, the aqueous solvent, and the type of radical terminating agent. The formula (1
) is 0.01 to 5 mol % based on the total amount of the vinyl monomer represented by formula (2) and the vinyl monomer represented by formula (2).

Conventionally known methods can be applied to the aqueous solution radical polymerization using the vinyl monomer represented by formula (1) and the vinyl monomer represented by formula (2).

There are no particular restrictions on the method or period for introducing the vinyl monomer into the copolymerization reaction system; the entire amount of vinyl monomer may be introduced into the copolymerization reaction system before the start of the copolymerization reaction, or It may be introduced into the copolymerization reaction system in parts, and the copolymerization reaction temperature can range from room temperature to the boiling point of the aqueous solvent.
Preferably it is 50 to 80°C. When the redox catalyst described above is used as a radical initiator, the copolymerization reaction temperature can be lowered by 10 to 30°C from the above temperature.

The second step of the production method according to the present invention is a step of adding a radical initiator to the binary copolymer obtained in the first step to obtain a binary copolymer in which the terminal of the main chain is radically activated. be.

If there is no unreacted vinyl monomer remaining in the reaction solution obtained in the first step, the reaction solution can be directly used in the second step; If the vinyl monomer from the reaction remains, the radically terminated binary copolymer is separated from the reaction solution, and the separated binary copolymer is sent to the second step.

The radical initiator used in the second step may be the same as the radical initiator used in the first step.

For the binary copolymer obtained by radical termination without using a radical terminator in the first step, the radical of the vinyl monomer represented by the formula (3) used in the next third step In order to add efficiently and selectively,
It is preferable to add an azobis compound having a hydroxyl group in the molecule as a radical initiator. Such azobis-based compounds are not limited in their application to binary copolymers obtained by radical termination using a radical terminator in the first step. Examples of azobis-based compounds having a hydroxyl group in the molecule include 2.2"-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2.2'-azobis[2-methyl-
N-+1,1-bis(hydroxymethyl)ethyl)propionamide], 2,2'-azobis[2-methyl-N
-(1.

1-bis(hydroxymethyl)-2-hydroquinethyl)propionamide] and the like.

In the second step of the production method according to the present invention, the amount of the radical initiator used to radically activate the binary copolymer obtained in the first step depends on the type of the radical initiator and the amount of the radical initiator used in the next third step. Although it varies depending on the type of vinyl monomer represented by formula (3) used in the step, it is usually in the range of 0.1 to 5% by weight based on the binary copolymer number obtained in the first step.

In the third step of the production method according to the present invention, the main chain end obtained in the second step is added to the binary copolymer with the formula (3
) is a step of radically adding a vinyl monomer represented by () to obtain a water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain.

Examples of the vinyl monomer represented by formula (3) include alkali metal salts, alkaline earth metal salts, and alkanolamine salts of allylsulfonic acid and methallylsulfonic acid.

The reaction rate between the binary copolymer whose main chain end is radically activated obtained in the second step and the vinyl monomer represented by formula (3) is determined by the type of radical terminator used in the first step. Although it varies depending on the type of radical initiator used in the second step, for example, whether or not an azobis compound having a hydroxyl group in the molecule is used, it is usually 1 to 1 mol per mole of the radically activated binary copolymer. 10 moles, preferably 1.5 to 5 moles. The radical addition reaction between the binary copolymer whose main chain terminals obtained in the second step is radically activated and the vinyl monomer represented by formula (3) is carried out by a radical solution polymerization method known per se as C. You can follow the steps below.

According to the production method of the present invention, in the radical addition reaction between the binary copolymer whose main chain terminal is radical-activated and the vinyl monomer represented by formula (3), the radical-activated binary copolymer is One molecule of (meth)allyl sulfonate is added to each terminal radical active site of the original copolymer. One molecule of sulfo per terminal radical active site
When radically adding an acidic vinyl monomer, the formula (3
) The (meth)allyl sulfonate represented by
It has extremely high reaction selectivity compared to (meth)acryloxysulfonates such as 2-(meth)acryloxyethylsulfonate and (meth)acrylamide sulfonates such as 2-acrylamido-2-methylpronognesulfonate. Therefore, the water-soluble vinyl copolymer of the present invention with a controlled terminal structure can be obtained.

The thus obtained water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain is extremely effective as a cement dispersant. When the water-soluble vinyl copolymer is used as a cement dispersant, its number average molecular weight measured by GPC method in terms of polyethylene glycol is 20.
00-15000 is preferable, 3000-100
00 is more preferable.

The cement dispersant according to the present invention is made of a water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain, which is obtained by the first step, second step, and third step explained above. When used, other agents may be used in combination for one purpose. Such other agents include air entraining agents, antifoaming agents, setting accelerators, setting retarders, rust preventives, preservatives, waterproofing agents, strength promoters, expansion agents, and the like.

The cement dispersant according to the present invention is usually 0.01 to 1.5% by weight, preferably 0.01 to 1.5% by weight, based on solid content, based on cement.
．． It is used in a proportion of 0.03 to 0.4% by weight. If the amount used is too small, the dispersion fluidity decreases, and the effect of maintaining the dispersion fluidity also tends to decrease at the same time, resulting in insufficient improvement in workability. On the other hand, if the amount used is too large, separation may occur or the setting delay may be increased, resulting in poor curing.

The cement dispersant according to the present invention can be applied to concrete and mortar prepared using various Portland cements, fly ash cements, blast furnace cements, silica cements, various mixed cements, and the like.

Hereinafter, in order to make the configuration and effects of the present invention more specific,
Examples will be given, but the present invention is not limited to these examples.

<Examples, etc.> Test category 1 (manufacture of water-soluble vinyl copolymer)/Example 1
(Production of water-soluble vinyl copolymer A) 60 parts of methacrylic acid (parts by weight, same hereinafter), methoxypolyethylene glycol (number of moles of ethylene oxide added, n = 9), 150 parts of monomethacrylate, 250 parts of water, and 2-mercaptoethanol 7 parts were placed in a flask, and 58 parts of a 48% (wt%) aqueous solution of sodium hydroxide was added to neutralize and dissolve uniformly, and the atmosphere was replaced with nitrogen. The temperature of the reaction system was maintained at 65°C in a hot water bath, and 50 parts of a 10% aqueous solution of ammonium persulfate was added to initiate polymerization. Polymerization was continued for 4 hours until the vinyl monomer remaining in the reaction system was almost consumed. The reaction continued. Then, 50 parts of a 10% aqueous solution of 2-mercaptoethanol was added to terminate radicals. The aqueous solution of the binary copolymer obtained by radical termination was purified by precipitation in an inproper tool and dried to obtain a binary copolymer (molecular weight 3700, sulfur content 11.6%). , 200 parts of the obtained binary copolymer (0.05
4 mol) and 450 parts of water were placed in another flask, and the atmosphere was replaced with nitrogen.

The temperature of the reaction system was maintained at 70°C in a hot water bath, and 30 parts of a 10% aqueous solution of ammonium persulfate was added to radically activate the binary copolymer, followed by a 20% aqueous solution of sodium methallylsulfonate. 80 parts (equivalent to 0.10 mol as sodium methallylsulfonate) were added, and the intermittent reaction was continued.

The radical addition reaction was completed.

After the obtained product was purified by precipitation as described above, it was analyzed and found to have a carboxyl value of 152 and a sulfur content of 3.1.
%, number average molecular weight was 4000 (GPC method, polyethylene glycol equivalent, same below). From this result, the product was sodium methacrylate/methoxypolyethylene glycol (n = 9) methacrylate = 70/30.
Water-soluble vinyl copolymer A in which 7.5% (corresponding to 1.9 pieces) of sodium methallylsulfonate per molecule of the copolymerized binary copolymer is added to the end of the main chain at a ratio of (molar ratio) Met.

・Example 2 (Production of water-soluble vinyl copolymer B) 0 parts of methacryl #f, methoxypolyethylene glycol (n = 9
) 101 parts of monomethacrylate, 240 parts of water and ? −
After charging 6 parts of mercaptoethanol into a flask and adding 67 parts of a 48% aqueous solution of sodium hydroxide to neutralize it and dissolve it uniformly, the temperature of the reaction system with the atmosphere replaced with nitrogen was raised to 65°C in a hot water bath. 10% of ammonium persulfate
% aqueous solution was added to start polymerization, and the polymerization reaction was continued for 4 hours until the vinyl monomer remaining in the reaction system was almost consumed. Then, 80 parts of a 5% aqueous solution of 2-mercaptoethyl acrylate was added to terminate radicals. The aqueous solution of the binary copolymer obtained by radical termination was purified by precipitation in an impropat tool and dried to obtain a zero-dimensional binary copolymer (molecular weight 5200, sulfur content 1.4%). Next, 150 parts (0.029 mol) of the obtained binary copolymer and 350 parts of water were charged into another flask, the atmosphere was replaced with nitrogen, and the temperature of the reaction system was kept at 70°C in a hot water bath. After adding 23 parts of a 10% aqueous solution of ammonium sulfate to radically activate the binary copolymer, further add 45 parts of a 20% aqueous solution of sodium methallylsulfonate (equivalent to 0.057 mol as sodium methallylsulfonate). was added, and the reaction was continued for 2 hours to complete the radical addition reaction.

After the obtained product was purified by precipitation as described above, analysis revealed that the carboxyl value was 221 and the sulfur content was 2.5.
%, number average molecular weight was 5,500. From this result, the product is 9 Sodium methacrylate/methoxypolyethylene glycol (n=9) methacrylate = 80/20
Water-soluble vinyl copolymer B in which 5.5% (corresponding to 1.8 pieces) of sodium methallylsulfonate per molecule of the copolymerized binary copolymer is added to the end of the main chain at a ratio of (molar ratio)
Met.

・Example 3 (Production of water-soluble vinyl copolymer C) 50 parts of methacrylic acid, methoxy polyethylene glycol (n=9
) 383 parts of monomethacrylate, 750 parts of water, and 4 parts of mercaptoacetic acid were placed in a flask, neutralized by adding 48 parts of a 48% aqueous solution of sodium hydroxide, and after uniformly dissolving, the atmosphere was replaced with nitrogen. The temperature of the system was maintained at 65°C in a hot water bath, and a 10% aqueous solution of ammonium persulfate4 was added.
0 part was added to start polymerization, and the polymerization reaction was continued for 5 hours until the vinyl monomer remaining in the reaction system was almost consumed, and then heated and stirred at 90 to 95 ° C for 1 hour. Radical termination was performed.

The aqueous solution of the binary copolymer obtained by radical termination was purified by precipitation in an impropat tool and dried to obtain a 9-dimensional binary copolymer (molecular weight 7800, sulfur content 0.3%). , 400 parts (0,051 mol) of the obtained binary copolymer
and 950 parts of water were placed in another flask, and the atmosphere was replaced with nitrogen. The temperature of the reaction system was maintained at 70°C in a hot water bath, and
．． After adding 35 parts of a 10% aqueous solution of 2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] to radically activate the binary copolymer, sodium methallylsulfonate was added. 100 parts of a 20% aqueous solution (0.13 mol as sodium methallylsulfonate) was added, and the reaction was continued for 2 hours to complete the radical addition reaction.

After the obtained product was purified by precipitation as described above, analysis revealed that the carboxyl value was 123 and the sulfur content was 0.9.
% and number average molecular weight was 8,000. From this result, the product is sodium methacrylate/methoxypolyethylene glycol (n=9) methacrylate=60/40
Water-soluble vinyl copolymer C in which 3.1% (equivalent to 1.6 pieces) of sodium methallylsulfonate per molecule of the copolymerized binary copolymer is added to the end of the main chain at a ratio of (molar ratio) Met.

Hereinafter, water-soluble vinyl copolymer D-H was obtained in the same manner as in Examples 1 to 3. The manufacturing conditions for water-soluble vinyl copolymers A-H are summarized in Table 1, and the analytical values are summarized in Table 2.

Table 1 (Manufacturing conditions for water-soluble vinyl copolymer) Note: In Table 1, Type: Type of water-soluble vinyl copolymer Condition 1: Radical terminator used Condition 2: Radically activated the binary copolymer Radical initiator conditions used for 39 Formula (1) Type and formula of vinyl monomer in the phase light component (
2) Type of vinyl monomer equivalent and molar ratio of both vinyl monomers (values in the relevant column in Table 1) Condition 4: Type and binary of vinyl monomer equivalent to formula (3) Charge ratio to copolymer (mol%) Woodworking = 2-mercaptoethanol wood 2:2-mercaptoethyl acrylate *3:1.2
- Ethanediol Zero 4: 3-Mercapto 1.2-Propanodiol Book 5: Ammonium Persulfate Tree 6: 2.2'-Azobis[2-Methyl-N-(2-hydroxyethyl) Propionami Tree 7. Methylsulfonic acid sodium salt Ki 8 Allylsulfonic acid sodium salt a: Methacrylic acid sodium salt b Niacrylic acid sodium salt C: Crotonate sodium salt d: Methoxypolyethylene glycol (n = 9) Methacrylate e: Methoxypolyethylene glycol (n = 23) Methacrylate f: methoxypoly(n=12) ethylene/poly(n=
3) Probile 7 glycol methacrylate Table 2 (analytical values) Note) In Table 2.

Type, book 7. Zero 8: Same analysis value l as in Table 1: (
Reaction ratio (molar ratio) of vinyl monomer equivalent to formula (1)/vinyl monomer equivalent to formula (2)) Analysis value 2: The amount of the formula (vinyl monomer equivalent to formula (2)) added to the terminal per molecule of the binary copolymer
3) Percentage and moles of equivalent vinyl monomer Tsubaki Comparative Example 1 (Synthesis of water-soluble vinyl copolymer R-1) 60 parts of methacrylic acid, 150 parts of methoxypolyethylene glycol (n=9) monomethacrylate, water Charge 250 parts and 7 parts of 2-mercaptoethanol into a flask,
After adding 58 parts of a 48% aqueous solution of sodium hydroxide to neutralize and uniformly dissolve, the atmosphere was replaced with nitrogen and H. The temperature of the reaction system was kept at 65°C in a hot water bath, and a 10% aqueous solution of ammonium persulfate was added. 50 parts were added to start polymerization, and the polymerization reaction was continued for 5 hours to complete the polymerization.

When the obtained product was purified by precipitation in Improper Tool and analyzed, it was found to have a carboxyl value of 175, a number average molecular weight of 4300, and a sodium methacrylate/methoxypolyethylene glycol (n:9) monomethacrylate = 73727 (mole ratio ) A water-soluble vinyl copolymer R-1 was obtained.

Comparative Example 2 (Synthesis of water-soluble vinyl copolymer R-2) 52 parts of methacrylic acid, 129 parts of methoxypolyethylene glycol (n=9) monomethacrylate, 48 parts of styrene sulfonic acid sodium salt, 390 parts of water, and 2-mercapto Pour 7 parts of ethanol into a flask, add 50 parts of a 48% aqueous solution of sodium hydroxide to neutralize it, and after dissolving it uniformly, keep the temperature of the reaction system at 60°C in a hot water bath with the atmosphere replaced with nitrogen. , 55 parts of a 10% aqueous solution of ammonium persulfate was added to start polymerization, and the polymerization reaction was continued for 5 hours to complete one polymerization.

The obtained product was precipitated and purified in Improper Tools, and then analyzed and found to have a carboxyl value of 140 and a number average molecular weight of 4100, and a copolymerization rate of 418% (copolymer A water-soluble vinyl copolymer R-2 in which each vinyl monomer was randomly bonded was obtained.

Comparative Example 3 (Synthesis of water-soluble vinyl copolymer R-3) 60 parts of methacrylic acid, methoxypolyethylene glycol (n=9)-T-7 methacrylate 150MA and 2 parts of water
Pour 50 parts into a flask and add 48% of sodium hydroxide.
After adding 58 parts of an aqueous solution to neutralize and uniformly dissolve, the atmosphere was replaced with nitrogen and the temperature of the 6 reaction system was adjusted to 65°C in a hot water bath.
40 parts of a 10% aqueous solution of ammonium persulfate was added to start polymerization, and the polymerization reaction was continued for 2 hours. 80 parts of a 20% aqueous solution of methallylsulfonic acid sodium salt (equivalent to 0.10 mol as methallylsulfonic acid sodium salt) was added, and the reaction was continued for 3 hours.

The obtained product was precipitated in Improper Tool and analyzed, and it was found that the carboxyl value was 171, the number average molecular weight was 9000, and the sulfur content was 0.2% or less, indicating that it was a copolymer of methallylsulfonic acid sodium salt. A water-soluble vinyl copolymer R-3 was obtained with a ratio of 0.2% (11 O phases per molecule of copolymer).

Comparative Example 4 (Synthesis of water-soluble vinyl copolymer R-4) 55 parts of methacrylic acid, 160 parts of methoxypolyethylene glycol (n-=9 monomethacrylate), 2 parts of water
70 parts of 2-mercaptoethanol and 6.5 parts of 2-mercaptoethanol were placed in a flask, and 53 parts of a 48% aqueous solution of sodium hydroxide was added to neutralize and dissolve uniformly.The temperature of the reaction system was then lowered by replacing the atmosphere with nitrogen. The temperature was maintained at 65° C. in a water bath, and 50 parts of a 10% aqueous solution of ammonium persulfate was added to start polymerization, and the polymerization reaction was continued for 4 hours. Then, 50 parts of a 10% aqueous solution of 2-mercaptox)i)-l was added to terminate radicals. The obtained aqueous solution of the binary copolymer was purified by precipitation in an impropat tool, dried, and analyzed, and the sulfur content was found to be 1.4%.

The number average molecular weight was 4,800. Next, 150 parts of the obtained binary copolymer and 350 parts of water were charged into another flask, and the temperature of the 8-reaction system in which the atmosphere was replaced with nitrogen was adjusted to 7 in a hot water bath.
After keeping the temperature at 0°C and adding 30 parts of a 10% aqueous solution of ammonium persulfate to radically activate the binary copolymer,
100 parts of a 20% aqueous solution of sodium 2-sulfoethyl methacrylate was added, and the reaction was continued for 2 hours to complete the radical addition reaction.

The resulting product was purified by precipitation in isopropanol and analyzed to find that it had a carboxyl value of 55, a sulfur content of 1.5%, a number average molecular weight of 4800, and a sodium content of 2 per molecule of the binary copolymer. A water-soluble vinyl copolymer R-4 was obtained in which 0.6% of -sulfoethyl methacrylate (corresponding to 0.2 molecules per molecule of the binary copolymer) was added to the end of the main chain.

Comparative Example 5 (Synthesis of water-soluble vinyl copolymer R-5) 15 parts of methacrylic #, 327 parts of methoxypolyethylene glycol (n=9) monomethacrylate, 550 parts of water, and 9 parts of 2-mercaptoethanol were charged into a flask.
After adding 15 parts of a 48% aqueous solution of sodium hydroxide to neutralize and uniformly dissolve, the temperature of the reaction system in which the atmosphere was replaced with nitrogen was maintained at 65°C in a hot water bath. The polymerization reaction was continued for 4 hours. Then, 50 parts of a 10% aqueous solution of 2-mercaptoethanol was added to terminate radicals. The obtained aqueous solution of the binary copolymer was purified by precipitation in an impropat tool, dried, and analyzed, and the sulfur content was 0.9% and the number average molecular weight was 4500. 200 parts of the binary copolymer and 450 parts of water were placed in another flask, the atmosphere was replaced with nitrogen, and the temperature of the reaction system was maintained at 70°C in a hot water bath.
After adding 30 parts of 0% aqueous solution to radically activate the binary copolymer,
80 parts of a 0% aqueous solution was added, and the reaction was continued for 2 hours to complete the radical addition reaction.

The obtained product was purified by precipitation in Improper Tool, and then analyzed, and found to have a carboxyl value of 27, a sulfur content of 2.0%, and a number average molecular weight of 4,800. From this result, the product is sodium methacrylate/methoxypolyethylene glycol (n=9) methacrylate=207
5.4% (equivalent to 1.6 bonds per molecule of binary copolymer) of methallylsulfonic acid sodium salt per molecule of the binary copolymer copolymerized at a ratio of 80 (mole ratio) is the end of the main chain. A water-soluble vinyl copolymer R-5 was obtained.

Test Category 2 (Concrete Test) Water-soluble vinyl copolymers A-H of the present invention and comparative water-soluble vinyl copolymers R-1-R shown in Tables 1 and 2
-5 as a cement dispersant, concrete tests were conducted under the following mixing conditions and methods to measure slump, air content, changes in these over time, compressive strength, and setting time. The results are summarized in Tables 3 and 4.

・Mixing conditions Ordinary Portland cement (compound of ordinary Portland cement manufactured by Onoda Corporation and ordinary Portland cement manufactured by Sumitomo Corporation) at 320 kg/■3, fine aggregate (Oi water-based sand, specific gravity 2.63) at 871 kg Kg/layer 3, coarse aggregate (crushed stone from Okazaki, specific gravity 2.66) at 979 Kg/■3 (fine aggregate '447%), and unit water volume at 160 Kg/3 (
water/cement ratio = 50%).

The cement dispersant has a target slump value of 1 on each side.
8c■, solid content equivalent to cement [1
It was added in an amount of 60% or less. Further, the air amount was adjusted by using an AE regulator (AE-300 manufactured by Gyosui Yushi Co., Ltd.) so that the target air amount was 4 to 6% on each side.

・Method: All materials (kneading amount: 35 kg) were put into a 60-ton tilting mixer under the above-mentioned mixing conditions, as described in Table wJ3 for the cement dispersant, and mixed at 28 r, p, m.

The mixture was kneaded and mixed for 3 minutes to make it homogeneous.

Immediately after kneading, samples were taken, and the stent and air amount were measured under controlled humidity at 20° C. and 80% RH. Subsequently, the mixture was kneaded for 2 r, p, and 60 to 90 minutes, and the slump and air content were measured in the same manner. In addition, for the concrete sampled immediately after mixing, 20
The setting time at ℃ was measured, and the compressive strength was measured after 7 days and after 28 days.

In addition, measurements of slump, air volume, compressive strength, and setting time are conducted in accordance with JIS-AIIOl, JIS-A1128, and JIS-A1128, respectively.
The test was conducted in accordance with JIS-A1108 and JIS-A6204 Annex 1.

Table 3 Note) In Table 3, type: type of water-soluble vinyl copolymer cement) component II & amount of agent added: solid content equivalent Sufu 77' residual rate: (slump after 90 minutes/kneading) Slump immediately after rise) A water-soluble vinyl copolymer with a controlled structure can be obtained.

When this is used as a cement dispersant, it is possible to impart excellent fluidity to the cement composition with little deterioration over time, and also to obtain a cured cement product having a desired strength with little setting delay.

Claims (1)

[Claims] 1. Vinyl monomer represented by the following formula (1) and the following formula (2)
) and vinyl monomer represented by formula (1)/vinyl monomer represented by formula (2) = 50/5.
After copolymerizing in the presence of a radical initiator at a ratio of 0 to 95/5 (molar ratio), a binary copolymer is obtained by radical termination, and then a radical initiator is added to the binary copolymer. In addition, after forming a radically activated binary copolymer, one or more vinyl monomers represented by the following formula (3) are radically added to the radically activated binary copolymer. 1. A method for producing a water-soluble vinyl copolymer having a sulfonic acid group at the end of its main chain, the method comprising adding a sulfonic acid group to the end of the main chain. Formula (1): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Formula (2): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Formula (3): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [Formula (1) ~(3), R^1~R^5, R^7 are simultaneously the same or different, H
Or CH_3. R^6 is an alkyl group having 1 to 3 carbon atoms. X and Y are alkali metals, alkaline earth metals, ammonium or organic amines. n is an integer from 5 to 25. ] 2. The water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain according to claim 1, wherein radical termination is performed by adding a compound having at least two active hydrogen groups such as hydroxyl groups or thiol groups in the molecule. Production method. 3.Claim 1, in which radical termination is carried out by adding a compound that shares a thiol group and an α,β-unsaturated hydrocarbon group in the molecule.
A method for producing a water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain as described above. 4. The method for producing a water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain according to claim 1, which comprises adding an azobis compound having a hydroxyl group in the molecule to form a radically activated binary copolymer. . 5. A cement dispersant comprising a water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain obtained by the production method according to claim 1, 2, 3 or 4. 6. The cement dispersant according to claim 5, wherein the water-soluble vinyl copolymer having a sulfonic acid group at the end of the main chain has a number average molecular weight of 2,000 to 15,000.