JPH0517191A - Cement admixture - Google Patents

Abstract

PURPOSE:To improve water-reducing effects, fluidity and workability by including a specific terpolymer and a bipolymer. CONSTITUTION:A cement admixture is obtained by carrying out redox polymerization of (a) 10-85mol% N-substituted-alpha,beta-unsaturated monocarboxamide derivative expressed by the formula [R. is H or lower alkyl; R2 is straight-chain or branched alkylene; X is H, alkali (alkaline earth) metal or (organic) ammonim] with (b) 10-85mol% unsaturated carboxylic acid (salt) and (c) 3-35mol% unsaturated carboxylic acid ester or vinyl acetate, providing (A) a copolymer having 750-300000 weight-average molecular weight (Mw), performing redox polymerization of 95-40mol% component (a) and 5-60mol% component (c), affording (B) a copolymer having 10000-300000Mw and blending 50-95wt.% component (A) with 50-5wt.% component (B). To a cement, is added 0.01-2.0wt.% aforementioned admixture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture having excellent properties as a dispersant, a water reducing agent, a fluidizing agent and the like.

[0002]

In recent years, cement compounds such as cement paste, mortar and concrete have been used in large amounts in the fields of civil engineering, construction, secondary concrete products and the like. Admixtures called dispersants, water-reducing agents, superplasticizers, etc. are added to these cement compounds for the purpose of improving slump and workability.

Conventionally, as such admixtures, those mainly containing lignin sulfonate and those mainly containing β-naphthalene sulfonate formalin condensate have been known, but both have advantages and disadvantages. There was no admixture that showed good performance in terms of dispersion fluidity and hardening characteristics of cement.

Japanese Patent Publication No. 2-16260 discloses an N-substituted-α, β-unsaturated monocarboxylic acid amide N-substituted with a sulfonic acid group-containing residue and an α, β-unsaturated monocarboxylic acid. It is described that the salt of the above copolymer is used as an admixture for cement. In addition, Japanese Patent Publication 1-55210
The publication proposes to use a homopolymer of 2-acrylamido-2-methylpropane sulfonate or a copolymer of this monomer and acrylamide and / or acrylate as a hydraulic cement admixture. ing.

Further, Japanese Patent Publication No. 2-5701 discloses that
It is described that a copolymer of 2-acrylamido-2-methylpropane sulfonate, unsaturated monocarboxylic acid salt, unsaturated carboxylic acid ester and / or acrylonitrile, styrene, vinyl acetate is used as a dispersant for cement. Has been done. In addition, JP-A-62-21695
No. 0 discloses a copolymer of 2-acrylamido-2-methylpropane sulfonate, an unsaturated carboxylic acid salt, and an adduct of unsaturated carboxylic acid with ethylene oxide and / or propylene oxide. Is proposed to be used as.

However, all of these admixtures or dispersants were required to be added in a large amount in order to obtain initial fluidity (slump), although slump loss was improved. Further, those containing a large amount of α, β-unsaturated monocarboxylic acid such as acrylic acid as a copolymerization component are
It was prone to delay in setting and was inferior in workability.

[0007]

DISCLOSURE OF THE INVENTION According to the present invention, the fluidity is excellent, the fluidity is prevented from lowering, the water-reducing effect is obtained even with a small amount of addition, and almost no delay in setting is observed. The present invention provides a cement admixture having excellent workability.

[0008]

The cement admixture of the present invention is characterized by containing the following copolymers (a) and (b).

(A): (A) N-substituted-α, β-unsaturated monocarboxylic acid amide derivative represented by Chemical formula 2.

[Chemical 2] (In the formula, R _{1 is} hydrogen or a lower alkyl group R _{2 is} a linear or branched alkylene group having 1 to 4 carbon atoms X is hydrogen, alkali metal, alkaline earth metal, ammonium, organic ammonium) (B) Unsaturated Carboxylic acid or its salt. (C) Unsaturated carboxylic acid ester or vinyl acetate. And a copolymerization ratio of (A) /
(B) / (C) = 10 to 85/10 to 85/3 to 35, and the weight average molecular weight is 750 to 3000.
00 copolymer. (B): (A) N-substituted-α, β shown in Chemical formula 2 above
-Unsaturated monocarboxylic acid amide derivatives. (C) A copolymer with an unsaturated carboxylic acid ester or vinyl acetate, the copolymerization ratio of which is (A) /
(C) = Copolymer having a weight average molecular weight of 10,000 to 300,000 in the range of 95/5 to 40/60.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Specific examples of the N-substituted-α, β-unsaturated monocarboxylic acid amide derivative of the above-mentioned monomer component (A) include 2-acrylamido-2-methylpropanesulfonic acid and 2-acrylamidoethanesulfone. Acid, 2-
Methacrylamidoethanesulfonic acid, 3-methacrylamidopropanesulfonic acid or salts thereof can be mentioned. Further, specific examples of the monomer component (B) of the copolymer include acrylic acid, methacrylic acid, maleic acid, crotonic acid, fumaric acid, citraconic acid, itaconic acid or salts thereof.

As the salt (X) in these monomer components (A) and (B), an organic ammonium salt such as an alkali metal salt, an alkaline earth metal salt, an ammonium salt, an amine salt or an alkanolamine salt is used.

Examples of the (C) unsaturated carboxylic acid ester or vinyl acetate as a copolymerization component include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, Butyl acrylate, dimethyl maleate, diethyl maleate, methyl crotonate,
Examples include ethyl crotonate, propyl crotonate, butyl crotonate, and vinyl acetate.

The (a) copolymer of the present invention comprises the above (A),
The copolymerization ratio of the copolymerization components of (B) and (C) is (A) / (B) / (C) = 10-85 / 10-85 / 3 in molar ratio.
It is necessary to be in the range of to 35, preferably 45
It is -85/10 to 45 / 3-15, and more preferably 45-70 / 20-45 / 5-10. If the molar ratio of the component (A) in the copolymerization ratio is too high, the initial fluidity is remarkably poor, and if it is too low, the properties of the cured product deteriorate. Also,
If the molar ratio of the component (B) is too high, the characteristics of the cured product will be significantly deteriorated, and if it is too low, the initial fluidity will be poor. Furthermore, (C)
If the molar ratio of the components is too high, the amount of air increases and the cement strength is remarkably inferior. On the contrary, if it is too low, the slump holding power is significantly deteriorated.

The weight average molecular weight of the copolymer (a) of the present invention is required to be in the range of 750 to 300,000, preferably 25,000 to 275,000, and more preferably 28,000 to 150,000.
When the weight average molecular weight exceeds 300,000, the viscosity of the aqueous solution becomes high, making it difficult to handle, and the initial fluidity is significantly deteriorated. On the contrary, when the molecular weight is less than 750, the slump holding power deteriorates.

The (b) copolymer of the present invention comprises the above (A),
The copolymerization ratio of the copolymerization component of (B) is (A) /
(B) = 95 / 5-40 / 60, preferably 80/20
It is necessary to be in the range of 50/50. When the copolymerization ratio exceeds 95/5, the holding power of the slump is significantly deteriorated, while when it is less than 40/60, the amount of air increases and the cement strength is poor.

The weight average molecular weight of the copolymer (b) of the present invention is required to be in the range of 10,000 to 300,000, preferably 50,000 to 150,000.
If the weight average molecular weight exceeds 300,000, the viscosity of the aqueous solution becomes high, making it difficult to handle, and the slump holding power is significantly deteriorated. On the other hand, when the molecular weight is less than 10,000, the amount of air increases and the slump holding power also deteriorates.

The (a) and (b) copolymers of the present invention are
It can be synthesized, for example, by radical polymerization, but using a redox initiator in which a persulfate and a reducing agent selected from sulfite, bisulfite and pyrosulfite are combined as a radical initiator, aqueous solution polymerization or suspension polymerization According to the above components (A), (B) and (C), or (A)
Those obtained by copolymerizing the component (C) and the component (C) are preferable in that remarkable fluidity is exhibited.

As the persulfate, sodium persulfate, ammonium persulfate, potassium persulfate and the like are used. Further, as the reducing agent to be used, sodium sulfite,
Potassium sulfite, ammonium sulfite, sodium bisulfite, potassium bisulfite, ammonium bisulfite, sodium pyrosulfite, potassium pyrosulfite, ammonium pyrosulfite and the like are used. In particular, a redox polymerization initiator in which ammonium persulfate and potassium bisulfite are combined is preferable.

(A) In the copolymerization reaction of the copolymer,
The components (A), (B), and (C) may be added to the reaction system at the same time. Further, in the components (A) and (B),
You may add (C) component.

The persulfate concentration is preferably 0.003 to 0.2 mol, and more preferably 0.007 to 0.1 mol, per mol of the vinyl monomer. The persulfate concentration is 0.
If it exceeds 2 moles, the weight average molecular weight of the obtained copolymer is lowered and the slump holding power is also deteriorated. Conversely, 0.00
When the amount is less than 3 mol, the viscosity of the aqueous solution becomes high, which makes the handling difficult and also causes deterioration of the slump holding power.

The reducing agent such as sulfite is 0.01 to 10 mol, preferably 0.01 to 0.
It is desirable to use them together in a ratio of 09 mol. This amount is 1
When it is more than 0 mol, the salt concentration of the obtained copolymer becomes high, and the durability of the cement is deteriorated. On the other hand, when the amount is less than 0.01 mol, the polymerization rate is lowered, and the initial fluidity and the slump holding power are significantly deteriorated.

The polymerization temperature is preferably 15 to 70 ° C. If the polymerization temperature exceeds 70 ° C., thermal decomposition of the persulfate will occur, the polymerization rate will decrease, and the initial fluidity and slump retention will deteriorate. Moreover, even if the polymerization temperature is lower than 15 ° C., the polymerization rate is lowered and the same phenomenon occurs.

The time required for the polymerization is usually about 20 minutes to 4 hours, but it is appropriately selected depending on the ratio of the monomers, the concentration of the aqueous solution and the like. The pH of the polymerization reaction is preferably 2 or more.

Further, within a range that does not impair the effects of the present invention,
Copolymerization components (A), (B) of the above (a) copolymer,
(C) and (b) copolymerization component (A) of the copolymer,
Other copolymerization components such as styrene, acrylonitrile, methacrylonitrile, acrylamide, and methacrylamide may be copolymerized with (C).

In the cement admixture of the present invention, (a),
The (b) copolymer is (a) / (b) = 50/50 to 95
/ 5 weight ratio, preferably 70/30 to 90/10 weight ratio. If the weight ratio exceeds 95/5, the slump holding power may be deteriorated and the setting may be delayed. On the other hand, when it is less than 50/50, the initial fluidity is poor, the air entrainment is high, and the cement strength is significantly deteriorated.

The combination of the molecular weights of the copolymers (a) and (b) used in combination is (a) / (b) = 100000.
-300000 / 70000-300000, preferably 130000-275000 / 90000-2950
00 polymer / polymer combination is desirable.

When the molecular weight combination of the (a) / (b) copolymer is a low molecular weight / high molecular weight combination of less than 100,000, the initial fluidity and the slump retention effect are slightly inferior, and the air entrainment is high. It is slightly deteriorated in terms of cement strength. Further, in the case of the combination of polymer / low molecular weight less than 70,000, the initial fluidity is good, but the slump holding effect is slightly deteriorated after 30 minutes, and the air amount is slightly increased from this point. . In the present invention, in both copolymers (a) and (b) used in combination, the monomer components (A) and (C) constituting each copolymer may be the same or different.

The blend of the copolymers (a) and (b) of the present invention is preferably added to the cement blend in an amount of 0.01 to 2.0% by weight based on the amount of cement. The admixture of the present invention can be used in the form of an aqueous solution or a powder, and the addition time can be any time between the kneading and molding of the cement product. In addition, if necessary, known admixtures of concrete such as AE agents, AE water reducing agents, high-performance AE water reducing agents, hardening accelerators, setting retarders, rust preventives, separation reducing agents, expanding agents, polymer admixtures, etc. It can also be used together.

[0029]

According to the present invention, a copolymer (a) obtained by copolymerizing the following monomer components (A), (B) and (C)
And a copolymer (b) obtained by copolymerizing the monomer components (A) and (C) together as a cement admixture, the copolymer of both components (A) and (B) or ( A),
(C) Copolymer of both components, and further (A), (B), (C)
Three-component copolymer or β- which is already on the market
Compared with a blend of naphthalene sulfonic acid formalin condensate (NSF) and isobutylene-maleic anhydride, excellent fluidity can be obtained, and deterioration of the fluidity with time can be prevented. In addition, even in a system in which the amount of water added is small, the fluidity is good and the hardening characteristics of cement are excellent, so that a hardened cement product with high strength can be obtained.

(A) N-substituted-α, β-unsaturated monocarboxylic acid amide derivative. (B) Unsaturated carboxylic acid or a salt thereof. (C) Unsaturated carboxylic acid ester or vinyl acetate.

[0031]

【Example】

Production Example 1 In a reactor equipped with a reflux condenser, a dropping funnel and a gas introduction tube and having an inner volume of 300 ml, equipped with a stirrer, 0.291 mol (6
6.6 g) of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS.Na) in water, 0.
10 mol (10.8 g) of sodium methacrylate (M
A.Na) aqueous solution and 0.025 mol (2.5 g) of methyl methacrylate (MMA) were added and the atmosphere was replaced with nitrogen.
The temperature was raised while flowing nitrogen. When the temperature reached 50 ° C, 0.017 mol (2.08 g) of potassium bisulfite dissolved in a small amount of water and 0.021 mol (4.75 g) of ammonium persulfate dissolved in a small amount of water were added. Polymerization was carried out for 1 hour while maintaining the polymerization temperature at 0 ° C. At this time,
AMPS ・ Na, MA ・ Na and M for all reaction systems
The MA concentration was 30 wt%.

The weight average molecular weight of the thus obtained copolymer was 130000 as measured by gel permeation chromatography (GPC). This was used as the copolymer (a) of Examples 3 and 8 to 10 described later.

Preparation Example 2 Based on the reactor of Preparation Example 1, 0.32 mol (72 g)
2-sodium 2-acrylamido-2-methylpropanesulfonate (AMPS.Na) aqueous solution and 0.08 mol (8 g) of methyl methacrylate (MMA) were added to replace nitrogen, and the temperature was raised while flowing nitrogen. When the temperature reached 50 ° C, potassium bisulfite 0.001 was dissolved in a small amount of water.
48 mol (0.59 g) and 0.005 mol (1.12 g) ammonium persulfate dissolved in a small amount of water were added,
Polymerization was carried out for 30 minutes while maintaining the polymerization temperature at 50 ° C. still,
At this time, the concentrations of AMPS · Na and methyl methacrylate were 30 wt% with respect to the total reaction system.

The weight average molecular weight of the thus obtained copolymer was 110000 as measured by gel permeation chromatography (GPC). This was used as the copolymer (b) of Examples 3 and 8 to 10 described later.

Hereinafter, the addition amounts of potassium bisulfite and ammonium persulfate were changed as appropriate, and the others were based on the above-mentioned production method, and the different molecular weights used in Examples 5 to 7 (a),
(B) A copolymer was produced.

Further, the copolymers used in Examples 11 to 16 were manufactured by changing the kinds or ratios of the copolymerizable monomers. However, in the production of the polymer (a) used in Example 16, potassium sulfite was used instead of potassium bisulfite.
In the production example of the copolymer (b), potassium pyrosulfite was used.

Examples 1 to 4 and Comparative Examples 1 to 5 Sodium 2-acrylamido-2-methylpropanesulfonate (AMPS.Na) / sodium methacrylate (MA.Na) / methyl methacrylate ( MMA) copolymer (a) and a mixture of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS.Na) / methyl methacrylate (MMA) copolymer (b) having different copolymerization molar ratios. The product was used as a hydraulic cement admixture and its performance was evaluated.

The composition A of the following Table 1 was weighed so that the kneading amount was 50 liters, and the total amount and a predetermined amount of the cement admixture (0.3 wt% of cement as pure matter) were adjusted to 10
The mixture was put into a 0 liter Erich mixer and kneaded for 90 seconds.

Remove the mixture from the mixer and immediately add J
The slump is measured according to IS A 1101, and the air amount is measured according to JIS A 1128.
This measured value was taken as the value immediately after.

After the same kneading was performed in another mixer, the setting time was set to Annex 1 of JIS A6204.
It was measured by the method described in. After measurement, mix 10
Transferred to a 0 liter tilting mixer, low speed (2 rp
After stirring for a predetermined time, the slump and the air amount over time were measured by the same test.

The following results are shown separately in Tables 2 and 3 below. Furthermore, without adding a cement admixture, an attempt was made to mix base concrete so that the slump value immediately after kneading would be 18.0 cm, and this mix composition is shown as composition B in Table 1. If the composition A of Table 1 is used without adding the cement admixture, there is no initial fluidity and substantially no kneading is possible.

From these results, it can be seen that the admixture of the present invention provides excellent initial fluidity even when the amount added is small and the water reduction rate is high, and the slump retention effect is good. Further, it shows almost no air entrainment, prevents retardation of setting, and does not adversely affect the cement characteristics after curing.

[0043]

[Table 1] Note) Cement: ordinary Portland cement (specific gravity 3.1)
6) Sand: Kisarazuyama sand (specific gravity 2.59) Coarse aggregate: Kuzuu crushed stone (specific gravity 2.71)

Examples 5 to 7 2-acrylamides having different molecular weights obtained in Production Examples
2-Methylpropanesulfonic acid ・ Na (AMPS ・ N
(a) / methacrylic acid / Na (MA / Na) / methyl methacrylate (MMA) copolymer (a) (molar ratio 70/2
4/6) and 2-acrylamide-2- having different molecular weights
Methyl propane sulfonic acid ・ Na (AMPS ・ Na) /
The performance as a hydraulic cement admixture was evaluated in the same manner for a blend in which a (b) copolymer of methyl methacrylate (MMA) (molar ratio 80/20) was combined.
Furthermore, the compressive strength after 7 days and 28 days after curing is determined by JIS
It was measured according to A1108. The results are shown in Table 4 and Table 5.
It is shown separately.

Examples 8 to 10 AMPS.Na/MA.Na/MMA obtained in Production Example
(A) copolymer (molar ratio 70/24/6, weight average molecular weight 130,000) and AMPS.Na/MMA (b) copolymer (molar ratio 80/20, weight average molecular weight 1)
10,000) and different blending ratios, the performance as a hydraulic cement admixture was evaluated in the same manner. The results are shown separately in Table 6 and Table 7.

Examples 11 to 16 The compositions of the copolymers (a) and (b) obtained in the production examples but having different copolymerization monomers were evaluated in the same manner as the hydraulic cement admixture. The results are shown separately in Table 8 and Table 9.

[0047]

[Table 2]Table 2: Compounding ratio of (a) / (b) copolymer = 80/20 (weight ratio)         Cement admixture * ¹ (a) Copolymer   (b) Copolymer           AMPS ・ Na / MA ・ Na weight average AMPS ・ Na / MMA weight average         / MMA (molar ratio)  Molecular weight  (Molar ratio)  Molecular weight   Actual 1 10/55/35 750 90/10 300,000 Application 2 49.5 / 40.5 / 10 275,000 70/30 295,000 Example 3 70/24/6 130,000 80/20 110,0004 10/85/5 300,000 50/50 10,000     1 70/30/0 120,000 − − Ratio 2 − − 70/30 110,000 Comparison 3 49.5 / 40.5 / 10 90,000 − − Example 4 5/90/5 100,000 98/2 100,0005 50/45/5 500 80/20 5,000   * 1) The amount of cement admixture added is 0.
3% (against cement). Note) For Examples 1 to 3 and Comparative Example 4, the AE agent
Vinsol (manufactured by Yamasou Chemical Co., Ltd.) 0.01%
Added

[0048]

[Table 3]Table 3: Compounding ratio of (a) / (b) copolymer = 80/20 (weight ratio)         Evaluation results           Slump change over time (cm)  Change in air volume over time (%)  Setting time (minutes)           Right after  Half an hour  60 minutes  90 minutes  Right after  Half an hour  60 minutes  90 minutes   First train  Termination    Actual 1 18.0 18.2 16.0 14.0 4.9 4.0 4.0 4.1 360 460 Application 2 19.0 21.0 20.0 16.0 4.0 3.5 3.8 4.5 355 450 Example 3 20.0 19.6 19.0 17.5 4.3 4.0 4.1 4.9 355 4454 19.0 21.0 20.0 14.0 4.5 4.0 4.9 5.2 360 465     1 23.5 20.0 7.5 − 1.0 1.1 1.0 − 365 510 Ratio 2 18.0 19.0 18.0 17.5 10.0 9.0 10.0 11.0 355 445 Comparison 3 20.0 19.8 17.0 9.0 6.2 4.6 4.6 4.7 360 460 Example 4 20.0 21.0 17.0 8.0 4.0 3.5 3.9 4.0 390 5405 19.0 20.0 18.0 10.0 7.2 6.8 6.5 6.9 360 470

[0049]

[Table 4] Note) The amount of cement admixture added is 0.3
wt%. In addition, about Examples 5-6, 0.01% of Vinsol (made by Yamamune Chemical Co., Ltd.) was added as an AE agent.

[0050]

[Table 5]Table 5: Compounding ratio of (a) / (b) copolymer = 80/20 (weight ratio)         Evaluation results          Slump change over time Air amount change over time Condensation time Compressive strength         (cm)  (%)  (Minutes)  (Kgf / cm ² )         Right after Half an hour 60 minutes 90 minutes  Right after Half an hour 60 minutes 90 minutes  First train Termination  7th 28th day Actual 5 18.0 18.2 16.0 14.0 5.1 4.2 4.2 4.3 360 455 650 820 Application 6 19.0 20.6 20.0 16.4 4.3 3.7 4.0 4.8 355 445 680 840Example 7 19.0 20.8 17.0 14.5 4.3 4.0 4.5 4.9 355 450 670 830

[0051]

[Table 6] Note) The amount of cement admixture added is 0.3
wt% (relative to cement). For Examples 8 to 9, Vinsol (manufactured by Yamasou Chemical Co., Ltd.) was used as the AE agent.
0.01% was added.

[0052]

[Table 7]          Slump change over time Air amount change over time Condensation time Compressive strength         (cm)  (%)  (Minutes)  (Kgf / cm ² )         Right after Half an hour 60 minutes 90 minutes  Right after Half an hour 60 minutes 90 minutes  First train Termination  7th 28th day Actual 8 20.0 19.0 18.0 16.0 4.1 3.7 3.9 4.2 360 460 670 850 Application 9 20.0 19.6 19.0 17.5 4.3 4.0 4.1 4.9 355 445 680 840Example 10 18.0 20.5 18.0 14.0 4.9 4.2 4.5 4.9 355 450 660 830

[0053]

[Table 8]         Cement admixture         (a) Copolymer  (b) Copolymer  Mixing ratio         (C) (C)          Composition AMPS / Na / MA / Na weight average Composition AMPS / Na / weight average a / b         Minute / (C) (molar ratio) Molecular weight   Minute (C) (molar ratio) Molecular weight  wt ratio     11 MA 70/15/15 70,000 MA 60/40 18,000 80/20 Actual 12 MA 70/15/15 70,000 EA 60/40 20,000 80/20 Application 13 MA 70/15/15 70,000 EMM 70/30 21,000 80/20 Example 14 DMM 70/27/3 60,000 DMM 80/20 20,000 70/30     15 DMM 70/27/3 60,000 DEM 80/20 22,000 70/30 16 VA 70/15/15 95,000 VA 60/40 16,000 60/40 MA: methyl acrylate EA: Ethyl acrylate EEM: Methyl methacrylate DMM: Dimethyl maleate DEM: Diethyl maleate VA: Vinyl acetate Note) The amount of cement admixture added is 0.3w as pure content
t% (relative to cement). In addition, in Examples 11 to 16
As for AE, Vinsol (Yamaso Chemical Co., Ltd.)
Manufactured) 0.01% was added.

[0054]

[Table 9]         Evaluation results           Slump change over time (cm)  Change in air volume over time (%)  Setting time (minutes)           Right after  Half an hour  60 minutes  90 minutes  Right after  Half an hour  60 minutes  90 minutes   First train  Termination        11 18.0 18.5 16.5 14.0 3.9 3.5 3.6 3.7 360 460 Actual 12 18.0 18.3 17.0 15.0 4.0 3.5 3.8 3.9 355 450 Application 13 19.0 19.6 18.0 16.0 4.3 4.0 4.1 4.5 355 445 Example 14 19.0 20.0 17.5 15.0 3.8 3.2 3.5 3.6 360 465     15 18.5 19.0 17.0 14.5 3.9 3.5 3.6 3.6 355 44516 18.0 19.0 16.0 14.0 4.1 4.0 4.0 4.0 360 460

[Procedure amendment]

[Submission date] September 13, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

The (b) copolymer of the present invention comprises the above (A),
The copolymerization ratio of the copolymerization component ( C ) is (A) / molar ratio.
( C ) = 95/5 to 40/60, preferably 80/20
It is necessary to be in the range of 50/50. When the copolymerization ratio exceeds 95/5, the holding power of the slump is significantly deteriorated, while when it is less than 40/60, the amount of air increases and the cement strength is poor.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0053

[Correction method] Change

[Correction content]

[0053]

[Table 8]         Cement admixture         (a) Copolymer  (b) Copolymer  Mixing ratio         (C) (C)          Composition AMPS / Na / MA / Na weight average Composition AMPS / Na / weight average a / b         Minute / (C) (molar ratio) Molecular weight   Minute (C) (molar ratio) Molecular weight  wt ratio     11 MA 70/15/15 70,000 MA 60/40 18,000 80/20 Actual 12 MA 70/15/15 70,000 EA 60/40 20,000 80/20 Application 13 MA 70/15/15 70,000 EMA    70/30 21,000 80/20 Example 14 DMM 70/27/3 60,000 DMM 80/20 20,000 70/30     15 DMM 70/27/3 60,000 DEM 80/20 22,000 70/30 16 VA 70/15/15 95,000 VA 60/40 16,000 60/40 MA: methyl acrylate EA: Ethyl acrylate EMA: Methacrylic acidDChill DMM: Dimethyl maleate DEM: Diethyl maleate VA: Vinyl acetate Note) The amount of cement admixture added is 0.3w as pure content
t% (relative to cement). In addition, in Examples 11 to 16
As for AE, Vinsol (Yamaso Chemical Co., Ltd.)
Manufactured) 0.01% was added.

Claims (4)

[Claims] 1. (a): (A) An N-substituted-α, β-unsaturated monocarboxylic acid amide derivative represented by Chemical formula 1, and (In the formula, R _{1 is} hydrogen or a lower alkyl group R _{2 is} a linear or branched alkylene group having 1 to 4 carbon atoms X is hydrogen, alkali metal, alkaline earth metal, ammonium, organic ammonium) (B) Unsaturated A copolymer of a carboxylic acid or a salt thereof and (C) an unsaturated carboxylic acid ester or vinyl acetate, the copolymerization ratio of which is (A) /
(B) / (C) = 10 to 85/10 to 85/3 to 35, and the weight average molecular weight is 750 to 3000.
00 copolymer, and (b): (A) N-substituted-α, β represented by the above chemical formula 1.
A copolymer of an unsaturated monocarboxylic acid amide derivative and (C) an unsaturated carboxylic acid ester or vinyl acetate, wherein the copolymerization ratio is (A) /
(C) = 95/5 to 40/60, and a cement admixture containing a copolymer having a weight average molecular weight of 10,000 to 300,000. 2. The cement admixture according to claim 1, wherein (B) in the component (a) is methacrylic acid or a salt thereof, and (C) in the component (a) is methyl methacrylate. Agent. 3. The component (C) in the component (b) is methyl methacrylate, ethyl methacrylate, methyl acrylate,
The cement admixture according to claim 1 or 2, which is ethyl acrylate, dimethyl maleate or diethyl maleate. 4. The copolymer of the above components (a) and (b) is produced by redox polymerization using persulfate and at least one of sulfite, bisulfite and pyrosulfite as a polymerization initiator. The cement admixture according to claim 1, 2 or 3, which has been added.