JPH07196354A - Admixture for cement - Google Patents

Abstract

PURPOSE:To improve performances as a water-reducing agent and further the executability and operating efficiency by comprising an amphoteric copolymer prepared by reacting a specific polymer with a hypohalogenous acid (salt) under alkaline conditions as an active component. CONSTITUTION:This admixture for a cement is produced by copolymerizing 99.9-20mol% alpha, beta-unsaturated carboxamide having 1000-1000000 weight-average molecular weight with 0.1-80mol% one or more anionic monomers selected from an alpha, beta-unsaturated monocarboxylic acid (salt), an a, fl-unsaturated dicarboxylic acid (salt) and an alpha, beta-unsaturated sulfonic acid (salt), providing an acrylamide-based copolymer, then reacting the resultant copolymer with a hypohalogenous acid (salt) in an amount of 1-100mol% based on carboxamide groups under alkaline conditions at pH >=10, affording a Hoffman PAM which is an amphoteric copolymer and then blending the resultant copolymer therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture containing an acrylamide amphoteric polymer as an active ingredient, which is produced by a Hoffmann decomposition reaction. More specifically, the present invention relates to a high-performance cement admixture capable of preventing the workability of concrete or mortar from deteriorating over time and improving its workability and workability.

[0002]

2. Description of the Related Art A cement mixture prepared by mixing cement, water and gravel, and an admixture loses fluidity due to progress of physical and chemical agglomeration of cement with the passage of time after kneading.
The workability and workability decrease over time. For example, when pumping cement mixture for pumping for some reason and then restarting pumping, the fluidity of the cement mixture in the pipe decreases, and when pumping is restarted, the pumping pressure rises or is blocked. There is also. Although the fluidity can be improved by increasing the amount of water, the strength of the concrete decreases significantly.

In order to solve these problems, conventional cement water-reducing agents include lignin sulfonate, oxycarboxylate, β-naphthalene sulfonate formalin condensate, sulfone group-containing melamine formaldehyde resin, polycarboxylate and the like. Is proposed. Recently, a partial hydrolyzate of polyacrylamide and a copolymer of anionic monomer and acrylamide have been proposed for the purpose of reducing slump loss. It is difficult to say that the fluidity, the slump holding power, the storage stability, etc. are sufficiently satisfied, and a high-performance water reducing agent has been desired.

[0004]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have found that cation-modified acrylamide polymer (hoffman PAM) which is cation-modified by Hoffman decomposition The present invention has been completed by discovering that the performance as a cement water reducing agent is remarkably improved when it has a molecular weight.

That is, the present invention has a weight average molecular weight of 1,0
Reaction of α, β-unsaturated carboxylic acid amide polymer in the range of 00 to 1,000,000 with 10 to 100 mol% of hypohalous acid (salt) with respect to carboxylic acid amide group under alkaline conditions of pH 10 or more An admixture for cement containing an amphoteric polymer obtained as the active ingredient, or having a weight average molecular weight of 1,0
Α, β-unsaturated carboxylic acid amide 99.9 to 20 mol% and α, β-unsaturated monocarboxylic acid (salt), α, β-unsaturated dicarboxylic acid (salt), α,
An acrylamide polymer obtained by polymerizing 0.1 to 80 mol% of one or more anionic monomers selected from β-unsaturated sulfonic acids (salts) to carboxylic acid amide groups under alkaline conditions of pH 10 or more. It is an admixture for cement which contains an amphoteric polymer obtained by reacting 1 to 100 mol% of hypohalous acid (salt) as an active ingredient.

The acrylamide polymer used in the Hoffman decomposition reaction in the present invention is a polymer of α, β-unsaturated carboxylic acid amide, or α, β-unsaturated carboxylic acid amide and α, β-unsaturated monocarboxylic acid amide. Hofmann decomposition of a copolymer with one or more anionic monomer selected from carboxylic acid (salt), α, β-unsaturated dicarboxylic acid (salt) and α, β-unsaturated sulfonic acid (salt) It has reacted. In the latter case, the amount of α, β-unsaturated carboxylic acid amide is 9
9.9-20 mol%, the amount of anionic monomer is 0.
It is usually 1 to 80 mol%. As the acrylamide-based polymer, a copolymer with one or more unsaturated copolymerizable monomers may be used as the third component.

Examples of the α, β-unsaturated carboxylic acid amide in the present invention include acrylamide and methacrylamide. Examples of α, β-unsaturated monocarboxylic acids (salts) include acids such as acrylic acid, methacrylic acid and crotonic acid or salts thereof, and examples of α, β-unsaturated dicarboxylic acids (salts) are anhydrous Examples of acids such as maleic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid or salts thereof, α, β-unsaturated sulfonic acid (salt),
Vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-
Phenylpropanesulfonic acid, 2-acrylamido-2
Examples thereof include acids such as methylpropanesulfonic acid and salts thereof.

Examples of the copolymerizable unsaturated monomer include:
Examples thereof include hydrophilic monomers, cationic monomers, lipophilic monomers and the like, and one or more kinds of these monomers can be applied. Specifically, as the hydrophilic monomer, for example, diacetone acrylamide, N, N-dimethylacrylamide, N, N-
Dimethylmethacrylamide, N-ethylmethacrylamide, N-ethylacrylamide, N, N-diethylacrylamide, N-propylacrylamide, N-acryloylpyrrolidine, N-acryloylpiperidine, N-
Acryloylmorpholine, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, various methoxypolyethylene glycol (meth) acrylates, N-vinyl-2-pyrrolidone and the like can be mentioned.

As the cationic monomer, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminopropyl methacrylamide, N, N Mention may be made of amines such as dimethylaminopropyl acrylamide and salts thereof.

Examples of the lipophilic monomer include N, N-di-n-propylacrylamide, Nn-butylacrylamide, Nn-hexylacrylamide and Nn-
Hexyl methacrylamide, Nn-octyl acrylamide, Nn-octyl methacrylamide, N-te
N-alkyl (meth) acrylamide derivatives such as rt-octylacrylamide, N-dodecylacrylamide, Nn-dodecylmethacrylamide, N, N-diglycidylacrylamide, N, N-diglycidylmethacrylamide, N- (4- N- (ω-glycid such as glycidoxybutyl) acrylamide, N- (4-glycidoxybutyl) methacrylamide, N- (5-glycidoxypentyl) acrylamide, N- (6-glycidoxyhexyl) acrylamide Xyalkyl) (meth) acrylamide derivative, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
(Meth) acrylate derivatives such as lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate and glycidyl (meth) acrylate, olefins such as acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, ethylene, propylene and butene. Examples thereof include styrene, divinylbenzene, α-methylstyrene, butadiene, isoprene and the like. The amount of the unsaturated monomer provided for the copolymerization varies depending on the type of the unsaturated monomer and the combination thereof, and cannot be said to be unconditional, but is generally in the range of 0 to 30% by weight.

A radical polymerization method is preferable as a polymerization method of the acrylamide (based) polymer, and water is used as a polymerization solvent.
A polar solvent such as alcohol or dimethylformamide can be applied. The monomer concentration is 2 to 40% by weight, preferably 5
~ 30% by weight. The polymerization initiator is not particularly limited as long as it is water-soluble. Specifically, in the peroxide system, for example, ammonium persulfate, potassium persulfate, hydrogen peroxide, te
Examples thereof include rt-butyl peroxide. in this case,
Although it can be used alone, it can also be used as a redox polymerization agent in combination with a reducing agent. Examples of the reducing agent include sulfite, bisulfite, iron, copper, salts of lower ions such as cobalt, organic amines such as N, N, N ′, N′-tetramethylethylenediamine, and further aldose and ketose. And reducing sugars such as

As the azo compound, 2,2'-azobis-2-amidinopropane hydrochloride, 2,2'-azobis-2,
4-Dimethylvaleronitrile, 4,4'-azobis-4-cyanovaleic acid and salts thereof can be used. Furthermore, it is also possible to use two or more of the above-mentioned polymerization initiators in combination.

The amount of the initiator added is 0.01 to
It is 10% by weight, preferably 0.1 to 8% by weight. In the case of a redox system, the amount of the reducing agent added to the initiator is 0.1 to 100%, preferably 0.2 to 80% on a molar basis. Further, if necessary, a chain transfer agent such as isopropyl alcohol, allyl alcohol, α-thioglycerol, mercaptosuccinic acid, thioglycolic acid, triethylamine or the like can be appropriately used.

The polymerization temperature is generally in the case of a single polymerization initiator.
The temperature is 30 to 90 ° C, which is lower in the case of a redox type polymerization initiator and is generally -5 to 50 ° C. Further, it is not necessary to keep the same temperature during the polymerization, and it may be appropriately changed as the polymerization proceeds, and the temperature is generally raised by the heat of polymerization generated with the progress of the polymerization.
At this time, if the polymerization is carried out at a high concentration, the polymerization may be carried out while removing heat, if necessary. The atmosphere in the polymerization vessel is not particularly limited, but it is preferable to replace with an inert gas such as nitrogen gas in order to carry out the polymerization rapidly. The polymerization time is not particularly limited, but is generally 1 to 20 hours.

The weight average molecular weight of the acrylamide polymer used in the present invention is determined by using an aqueous GPC column (for example, Sh
odex OHpak SB-800 HQ series) and it is in the range of 1,000 to 1,000,000 in pullulan conversion. When the weight average molecular weight exceeds 1,000,000, the viscosity of the aqueous solution becomes high, which causes trouble in handling and the average molecular weight
If it is less than 1,000, there is a problem that the flow performance is poor.

The Hoffmann decomposition reaction is carried out by reacting the acrylamide polymer obtained above with a hypohalite under an alkaline condition of pH 10 or more. Examples of the hypohalite include metal salts of hypochlorous acid or alkaline earth metal salts, such as sodium hypochlorite, potassium hypochlorite, lithium hypochlorite, calcium hypochlorite, and Examples thereof include magnesium chlorite and barium hypochlorite. Similarly, an alkali metal salt or an alkaline earth metal salt of hypobromic acid or hypoiodic acid can be used. The amount of hypochlorite added to the acrylamide polymer is 10 to 100 mol% based on the amount of the carboxylic acid amide group when the anionic monomer is not copolymerized, and 1 to 100 when the anionic monomer is copolymerized. Mol%. The addition amount of the polymer with respect to the total amount of the monomers is 0.1 X mol% to X mol%, when the amount of the carboxylic acid amide group is X mol%, when the anionic monomer is not copolymerized.
It is preferably 0.4X to Xmol%, and 0.01X to Xmol%, preferably 0.2X to Xmol% when an anionic monomer is copolymerized.

Since the Hoffmann decomposition reaction is carried out under alkaline conditions of pH 10 or more, usually 0.8 to 4.0 times as much alkaline substance as the number of moles of hypohalous acid (salt) are allowed to coexist. Examples of the alkaline substance include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, etc. Among them, sodium hydroxide, potassium hydroxide, alkali metal hydroxides such as lithium hydroxide are preferable. .

When the Hofmann decomposition reaction is carried out by mixing a hypohalite and an alkaline substance in an aqueous solution of an acrylamide polymer, the mixing order is not particularly limited, and the alkaline substance may be added first. However, there is no problem with hypohalous acid. However, if the reaction temperature becomes high, gelation may occur. Therefore, it is preferable to add the alkaline substance first or mix the alkaline substance and the hypohalous acid salt in advance and then add. As a mixing method, a line mixer may be used, or a method of mixing while stirring in a reaction tank may be used.

The reaction temperature may be in the range of 0 to 110 ° C. The reaction time cannot be generally stated because it depends on the reaction temperature or the reaction concentration, but it is 30 to 40 hours at 0 ° C, 3 to 4 hours at 20 ° C, several tens of minutes at 50 ° C, several minutes at 65 ° C, 80 Within several tens of seconds at ° C. The Hoffmann decomposition reaction is an exothermic reaction, and if the reaction concentration or the Hoffman decomposition rate increases, the temperature rise cannot be ignored.In such a case, the liquid before mixing should be cooled in advance or the heat of reaction should be removed. There is a need to. The reaction temperature does not have to be kept constant, and the reaction time may be shortened in consideration of the temperature increase due to the heat of reaction.

Hoffman PAM manufactured under the above conditions
Is an amphoteric polymer, and the cation equivalent measured by colloid titration at pH 2 is approximately 0.5 to 10.0 meq./g when anionic monomer is not copolymerized, and anion measured by colloid titration at pH 10. Equivalent weight is about 0.1-10.0
It is in the range of meq./g. When an anionic monomer is copolymerized, the cation equivalent is generally in the range of 0 to 10.0 meq./g and the anion equivalent is generally in the range of 0.1 to 12.0 meq./g.

The Hoffman PAM after the reaction can be used as it is after the reaction. However, since the hypohalous acid salt becomes a halogenated salt such as NaCl or NaBr after the Hoffmann decomposition reaction, it is preferable to remove these inorganic salts. As the desalting method, known methods such as a method using a separation membrane, a method using an ion exchange resin, and a method of reprecipitation purification with an aqueous organic solvent such as methanol can be applied.

The cement admixture of the present invention containing the Hofmann-decomposed acrylamide (based) polymer as an active ingredient can be mixed with cement to form a cement composition.
The amount of acrylamide polymer added to cement varies depending on the type of cement, and when fine aggregate or coarse aggregate is used, it cannot be said unequivocally because it varies depending on the type and blending ratio. 0.01 to
2.5% by weight is suitable. If it is less than 0.01%, sufficient workability cannot be obtained, and if it exceeds 2.5%, it is economically disadvantageous. The type of cement used is not limited, and for example, ordinary Portland cement, early-strength Portland cement, alumina cement, fly ash cement, blast furnace cement, silica cement, various mixed cements and the like can be used. As fine aggregate, river sand, land sand, mountain sand, sea sand, blast furnace slag, etc. can be used, and as coarse aggregate, river gravel, land gravel, mountain gravel, etc. can be used, all of which can be used in ordinary cement compositions.

Further, general admixtures, admixtures, that is, air entraining agents, early strengthening agents, retarding agents, waterproofing agents, rust preventives, water retaining agents,
Colorants, preservatives, fiberglass, fly ash,
It is possible to use together with blast furnace slag, silica powder and the like. The cement admixture of the present invention is added to cement in an amount of 0.
Those added with 01 to 2.5% by weight can maintain the same fluidity even when the amount of water used in the cement composition is reduced by 15 to 30% by weight as compared with the case where it is not used. The Hoffman PAM used in the present invention can be used as a water reducing agent for gypsum, for example, in addition to cement.

[0024]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not necessarily limited to the following examples. Note that% means% by weight unless otherwise specified.

Example 1 40% acrylamide 40 was placed in a 1 L stainless (SUS304) Dewar bottle equipped with a stirrer, a thermometer, and a nitrogen gas inlet tube.
An aqueous solution prepared by mixing 0.0 g (2.25 mol) and 240.0 g of ion-exchanged water was adjusted to pH 4.5 with 10% hydrochloric acid, and the temperature of the solution was 15 ° C.
Adjusted to. After blowing nitrogen gas for 15 minutes to replace it,
While stirring, 10% ammonium persulfate aqueous solution and 10% sodium hydrogen sulfite aqueous solution were added to initiate polymerization.
The internal temperature rose to 84 ° C. After that, stirring was continued for 2 hours, and the weight average molecular weight of the obtained acrylamide polymer was 13,400 when measured using a GPC column (Shodex OHpak KB-80M * 2) manufactured by Showa Denko KK. This is polymer A
And Then, dilute the polymer A solution to 20 wt% and
50.0 g (0.42 mol (monomer unit)) was placed in a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, and the temperature was 10 ° C.
84.4 g of 40% caustic soda aqueous solution (0.
84 mol) and 12.5% sodium hypochlorite aqueous solution 251.4 g (0.4
(2 mol) is added simultaneously, the reaction starts immediately
After a second, the temperature of the reaction solution rose to 75 ° C. Stirring was continued for 5 minutes while cooling with air, and the cation value of the reaction solution was examined.
The value was 7.5 meq./g and the anion value was 1.1 meq./g. This is designated as Polymer A-1.

Example 2 150.0 g of a 20 wt% solution of polymer A (0.42 mol (monomer unit)), and 50.6 g (0.51 mol) of 40% aqueous sodium hydroxide solution
, 10.8% sodium hypochlorite aqueous solution 150.8g (0.25mol)
The reaction was carried out in the same manner as in Production Example 1 except that the polymer solution before the reaction was changed to 35 ° C. 20 seconds after the addition, the temperature of the reaction solution rose to 77 ° C., and stirring was continued for 5 minutes while air cooling. This is designated as Polymer A-2. Cation value is 5.9me
The anion value was 1.0 meq./g.

Example 3 To 150.0 g of a 20 wt% solution of polymer A, 33.8 g (0.34 mol) of 40% aqueous sodium hydroxide solution and 100.5 g (0.17 mol) of 12.5% aqueous sodium hypochlorite solution were added. The reaction was performed in the same manner as in Production Example 1 except that the combined solution was changed to 35 ° C.
20 seconds after the addition, the temperature of the reaction solution rose to 77 ° C., and stirring was continued for 5 minutes while air cooling. This is designated as Polymer A-3. Cation value is 4.3 meq./g, anion value is 1.5 meq./g
Met.

Comparative Example 1 150.0 g of a 20 wt% solution of polymer A, 4.2 g (0.04 mol) of 40% aqueous sodium hydroxide solution and 12.6 g (0.02 mol) of 12.5% aqueous sodium hypochlorite solution were added. The reaction was performed in the same manner as in Production Example 1 except that the solution was changed to 70 ° C. This is designated as Polymer A-4. The cation value was 0.7 meq./g and the anion value was 0.5 meq./g.

Comparative Example 2 150.0 g (0.42 mol (monomer unit)) of 20 wt% solution of polymer A, 8.4 g (0.08 mol) of 40% caustic soda aqueous solution
Was added and a hydrolysis reaction was carried out at 65 ° C. for 2 hours. This is designated as Polymer A-5. The anion value was 2.5 meq./g.

Example 4 40% acrylamide 40 was placed in a 1 liter stainless (SUS304) Dewar equipped with a stirrer, a thermometer and a nitrogen gas inlet tube.
An aqueous solution prepared by mixing 0.0 g (2.25 mol) and 400.0 g of ion-exchanged water was adjusted to pH 4.5 with 10% hydrochloric acid, and the temperature of the solution was adjusted to 20 ° C. After purging the system by blowing nitrogen gas for 15 minutes, 10% ammonium persulfate aqueous solution and 10% sodium bisulfite aqueous solution were charged with stirring to initiate polymerization. The internal temperature rose to 75 ° C. Then, stirring was continued for 2 hours, and the weight average molecular weight of the obtained acrylamide polymer was measured by a GPC column (Shodex OHpak manufactured by Showa Denko KK).
It was 34,700 when measured using KB-80M * 2).
This is referred to as polymer B. Then polymer B solution 150.0 g (0.
42 mol (monomer unit)) was placed in a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, and adjusted to 35 ° C.
While stirring, 33.8 g (0.34 mol) of 40% caustic soda solution
The reaction started immediately when 100.5 g (0.17 mol) of 12.5% sodium hypochlorite aqueous solution was added at the same time, and after 30 seconds, the temperature of the reaction solution rose to 70 ° C. When the cation value of the reaction solution was examined, it was 4.3 meq./g, and the anion value was 1.5 meq./g. This is designated as Polymer B-1.

The acrylamide polymers obtained in Examples and Comparative Examples were evaluated for their performance as a cement water reducing agent by JI.
Tested according to the method of SR-5201. That is, in 1 kg of ordinary Portland cement, the solid content of the cement is 7.
260 g of water containing 5, 5.0, 2.5, and 1.5 g (however, 1.25 g in Example 4) of the acrylamide polymer was added, and the mixture was stirred for 3 minutes with a mortar mixer, and then the flow value of cement was measured. Table 1 shows the composition of acrylamide polymer and the flow value. The flow value of the cement paste when the polymer was not added was 150.

[0032]

[Table 1]

Example 5 In a 1-liter stainless (SUS304) Dewar bottle equipped with a stirrer, a thermometer, and a nitrogen gas inlet tube, 40% acrylamide 278.
8g (1.57mol), 80% acrylic acid 60.58g (0.67mol),
An aqueous solution prepared by mixing 460.6 g of deionized water and ion-exchanged water was adjusted to pH 4.5 with 10% sodium hydroxide, and the temperature of the solution was adjusted to 20 ° C. After blowing nitrogen gas for 15 minutes to replace the inside of the system, with stirring, 10% ammonium persulfate aqueous solution and 10%
Polymerization was initiated by adding an aqueous solution of sodium hydrogen sulfite. The internal temperature rose to 75 ° C. Then, stirring was continued for 2 hours, and the weight average molecular weight of the obtained anionic acrylamide polymer was measured by a GPC column (Shodex OHpa) manufactured by Showa Denko KK
When measured using k KB-80M * 2), it was 30,300. This is referred to as polymer C. Then polymer C solution 150.0g
(0.42 mol (monomer unit)) was placed in a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, heated to 50 ° C., and stirred while stirring 16.8 g (0.17 mol) of a 40% caustic soda aqueous solution. And 12.5% sodium hypochlorite aqueous solution 50.1g (0.08mol)
When was added simultaneously, the reaction started immediately, and after 20 seconds, the temperature of the reaction solution rose to 75 ° C. When the cation value of the reaction solution was examined, it was 1.6 meq./g, and the anion value was 2.4 meq./g. This is designated as Polymer C-1.

Example 6 33.6 g of 40% aqueous sodium hydroxide solution based on 150.0 g of polymer C
(0.34 mol), 100.1 g of 12.5% sodium hypochlorite aqueous solution
(0.17 mol), and the reaction was carried out in the same manner as in Example 5 except that the polymer solution before the reaction was changed to 35 ° C. 20 seconds after the addition, the temperature of the reaction solution rose to 77 ° C. This is polymer C
-2. The cation value is 3.5 meq./g and the anion value is 3.
It was 0meq./g.

Example 7 58.8 g of 40% aqueous caustic soda solution was added to 150.0 g of polymer C.
(0.59 mol), 175.2 g of 12.5% sodium hypochlorite aqueous solution
(0.29 mol) was reacted in the same manner as in Example 5 except that the polymer solution before the reaction was changed to 20 ° C. 50 seconds after the addition, the temperature of the reaction solution rose to 74 ° C. This is polymer C
-3. The cation value is 5.7 meq./g and the anion value is 3.
It was 4 meq./g.

Example 8 A 1 liter stainless steel (SUS304) Dewar equipped with a stirrer, a thermometer and a nitrogen gas inlet tube was charged with 40% acrylamide 310.
An aqueous solution prepared by mixing 55 g (1.75 mol), 35.79 g (0.31 mol) of maleic acid, and 453.66 g of ion-exchanged water was adjusted to pH 4.5 with 10% caustic soda, and the temperature of the solution was adjusted to 20 ° C. After blowing nitrogen gas for 15 minutes to replace the system,
While stirring, 10% ammonium persulfate aqueous solution and 10% sodium hydrogen sulfite aqueous solution were added to initiate polymerization.
The internal temperature rose to 74 ° C. Then, stirring was continued for 2 hours, and the weight average molecular weight of the obtained anionic acrylamide polymer was measured by a GPC column (Shodex OHpak KB-8 manufactured by Showa Denko KK).
It was 28,700 when measured using 0M * 2). This is designated as Polymer D. Next, polymer D solution 150.0 g (0.39
Mol (monomer unit)) was placed in a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, heated to 50 ° C., and stirred while stirring, 54.0 g (0.54 mol) of 40% caustic soda aqueous solution and 12 .
When 160.68 g (0.27 mol) of a 5% sodium hypochlorite aqueous solution was added at the same time, the reaction immediately started, and after 20 seconds, the temperature of the reaction solution rose to 75 ° C. When the cation value of the reaction solution was examined, it was 5.8 meq./g, and the anion value was 3.3 meq./g. This is designated as Polymer D-1.

Example 9 In a 1 L stainless (SUS304) Dewar bottle equipped with a stirrer, a thermometer, and a nitrogen gas inlet tube, 40% acrylamide 332.
73 g (1.87 mol), 25% sodium vinyl sulfonate 107.
An aqueous solution prepared by mixing 63 g (0.21 mol) and 359.64 g of ion-exchanged water was adjusted to pH 4.5 with 10% sodium hydroxide, and the temperature of the solution was adjusted to 20 ° C. After purging the system by blowing nitrogen gas for 15 minutes, 10% ammonium persulfate aqueous solution and 10% sodium bisulfite aqueous solution were charged with stirring to initiate polymerization. The internal temperature rose to 75 ° C. afterwards
Stirring was continued for 2 hours, and the weight average molecular weight of the obtained anionic acrylamide polymer was measured using a GPC column (Shodex OHpak KB-80M * 2) manufactured by Showa Denko.
It was 26,700. This is referred to as polymer E. Next, 150.0 g of polymer C solution (0.39 mol (monomer unit)) was placed in a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, heated to 50 ° C., and stirred with 40% caustic soda. Aqueous solution 5
4.6 g (0.55 mol) and 12.5% sodium hypochlorite aqueous solution 162.
The reaction started immediately when 6 g (0.27 mol) was added at the same time.
After a second, the temperature of the reaction solution rose to 72 ° C. The cation value of the reaction solution was 5.6 meq./g and the anion value was 2.2 me.
It was q./g. This is designated as Polymer E-1.

Comparative Example 3 0.42 g of 40% caustic soda aqueous solution based on 150.0 g of polymer C
(4.2 mmol), 12.5% sodium hypochlorite aqueous solution 1.2
The reaction was carried out in the same manner as in Example 5 except that the amount was changed to 5 g (2.1 mmol). This is designated as Polymer C-4. The cation value of this reaction solution was 0.1 meq./g or less.

Comparative Example 4 318.7 g of 40% acrylamide was placed in a 1 liter glass separable flask equipped with a stirrer, a thermometer, and a nitrogen gas introducing tube.
(1.79 mol), 40.4 g (0.45 mol) of 80% acrylic acid and 174.3 g of ion-exchanged water were mixed to adjust the pH to 4.5 with a 10% aqueous sodium hydroxide solution, and the temperature of the solution was adjusted to 15 ° C.
Blow nitrogen gas for 15 minutes to replace it, then stir it while stirring.
A 10% aqueous solution of ammonium persulfate and a 10% aqueous solution of sodium hydrogen sulfite were added to initiate polymerization under air cooling. The internal temperature is
It rose to 88 ° C. Then, stirring was continued for 2 hours, and the weight average molecular weight of the obtained acrylamide polymer was measured by using a GPC column (Shodex OHpak KB-80M * 2) manufactured by Showa Denko KK, and it was 17,800. This is designated as Polymer F. The anion value was 2.8 meq./g.

The acrylamide polymers obtained in Examples and Comparative Examples were evaluated for their performance as a cement water reducing agent by JI.
Tested according to the method of SR-5201. That is, in 1 kg of ordinary Portland cement, the solid content of the cement is 7.
260 g of water containing 5, 5.0, 2.5, and 1.25 g of acrylamide polymer was added, and the mixture was stirred with a mortar mixer for 3 minutes, and then the flow value of cement was measured. Table 3 shows the composition and flow value of the acrylamide polymer. The flow value of the cement paste when the polymer was not added was 144.

[0041]

[Table 2]

[0042]

INDUSTRIAL APPLICABILITY The Hoffman decomposition reaction product of the (meth) acrylamide-based polymer of the present invention has a larger cement water-reducing performance than the conventionally known (meth) acrylamide copolymer obtained by simply copolymerizing an anionic monomer. Can be improved. Furthermore, the use of a (meth) acrylamide-based polymer in which an anionic monomer is copolymerized can remarkably enhance the effect produced by the Hoffman decomposition reaction. The primary amino group introduced by the Hoffmann decomposition reaction is a functional group that exhibits a cationic property in an acidic aqueous solution, and although there were many examples of application to a flocculant and an additive for papermaking, such a cement water reducing agent is Conventionally, there was no idea of utilizing such a functional group. Although its action is unknown, it has been clarified that the ability of the acrylamide-based water reducing agent can be greatly improved by the present invention, and it is expected to be widely used in the future.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Atsushi Ito 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd. (72) Shoichi Araseki 1190 Kasama-cho, Sakae-ku, Yokohama, Kanagawa Mitsui Toatsu Inside Chemical Co., Ltd.

Claims (4)

[Claims] 1. A polymer of α, β-unsaturated carboxylic acid amide having a weight average molecular weight in the range of 1,000 to 1,000,000 is added in an amount of 10 to 100 mol% based on the carboxylic acid amide group under alkaline conditions of pH 10 or more. An admixture for cement containing an amphoteric polymer obtained by reacting hypohalous acid (salt) as an active ingredient. 2. An α, β-unsaturated carboxylic acid amide having a weight average molecular weight in the range of 1,000 to 1,000,000 99.9 to 20.
Mol% and α, β-unsaturated monocarboxylic acid (salt), α,
An acrylamide polymer obtained by polymerizing 0.1 to 80 mol% of one or more anionic monomer selected from β-unsaturated dicarboxylic acid (salt) and α, β-unsaturated sulfonic acid (salt) is used. Under the above alkaline conditions, 1 to 100 mol% of hypohalous acid (salt) based on carboxylic acid amide group
An admixture for cement containing as an active ingredient an amphoteric polymer obtained by reacting. 3. The cement admixture according to claim 1, wherein the α, β-unsaturated carboxylic acid amide is acrylamide or methacrylamide. 4. A cement composition comprising a cement admixture according to claim 1, 2 or 3 and cement as main components.