JPH07144948A - Admixture for cement - Google Patents

Abstract

PURPOSE:To prevent the reduction of the workability of concrete or mortar with the lapse of time and to improve applicability and work efficiency by blending cement with an amphoteric polymer obtd. by bringing an anionic acrylamide polymer into Mannich reaction. CONSTITUTION:An anionic (meth)acrylamide polymer having a wt. average mol. wt. of 1,000-500,000 is produced by copolymerizing 95-20mol% (meth) acrylamide with 5-80mol% one or more kinds of anionic monomers selected from among alpha,beta-unsatd. monocarboxylic acid (salt), alpha,beta-unsatd. dicarboxylic acid (salt) and alpha,beta-unsatd. sulfonic acid (salt), and 1-50mol% (meth)acrylamide in the polymer is cationized by Mannich reaction to obtain an amphoteric acrylamide polymer. This polymer is added to cement by 0.05-2.5wt.% (expressed in terms of solid matter). At this time, the polymer may be used in combination with a general admixture for cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Mannich-modified acrylamide amphoteric polymer. More specifically, the present invention relates to a high-performance cement water-reducing agent that can prevent the workability of concrete or mortar from deteriorating over time and improve its workability and workability.

[0002]

Cement, water and gravel, a cement mixture prepared by mixing an admixture or admixture, after kneading, physical and chemical agglomeration of the cement progresses with the passage of time, and loses fluidity, The workability and workability decrease over time. For example, when pumping a cement mixture for some reason to stop the pumping and then restart the pumping,
The fluidity of the cement mixture in the pipe may decrease, and the pumping pressure may suddenly rise or be blocked when the pumping is restarted. 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, as a conventional cement water reducing agent, lignin sulfonate, oxycarboxylate, β-naphthalene sulfonate formalin condensate, sulfo group-containing melamine formaldehyde resin, polycarboxylate, etc. have been proposed. ing.
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.

[0003]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have found that an acrylamide polymer cation-modified by the Mannich reaction has a predetermined molecular weight and an anion. The present invention has been completed by discovering that the performance as a cement water-reducing agent is remarkably improved when the ratio of the functional group of the cation and the functional group of the cation is fixed. That is, the present invention has a weight average molecular weight
In the range of 1,000 to 500,000, (1) α, β-unsaturated carboxylic acid amide 95 to 20 mol% and (2) α, β-unsaturated monocarboxylic acid (salt), α, β-unsaturated dicarboxylic acid An acrylamide polymer obtained by copolymerizing 5 to 80 mol% of one or more anionic monomers selected from acid (salt) and α, β-unsaturated sulfonic acid (salt), )
It is an admixture for cement containing an amphoteric polymer obtained by reacting an α, β-unsaturated carboxylic acid amide in an amount of 1 to 50 mol% with respect to the total monomer units as an active ingredient.

The acrylamide polymer used in the present invention includes acrylamide (or methacrylamide) and α, β-unsaturated monocarboxylic acid (salt), α, β-unsaturated dicarboxylic acid (salt), α, β-unsaturated sulfonic acid (salt)
Mannich modification of a copolymer with one or more anionic monomers selected from the above. The copolymerization ratio of acrylamide (or methacrylamide) and anionic monomer is 95 to 20: 5 to 80 (molar ratio),
A copolymer with one or more unsaturated copolymerizable monomers may be used as the third component.

Examples of α, β-unsaturated monocarboxylic acids (salts) include acids such as acrylic acid, methacrylic acid and crotonic acid and / or their salts, and α, β-unsaturated dicarboxylic acids (salts). Examples include maleic anhydride, maleic acid,
Examples of acids such as fumaric acid, itaconic acid, citraconic acid and / or their salts, and α, β-unsaturated sulfonic acids (salts) include vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, and styrene sulfonic acid. , 2-acrylamido-2-phenylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and / or salts thereof.

Examples of the copolymerizable unsaturated monomer include:
Examples thereof include hydrophilic monomers, ionic monomers, lipophilic monomers and the like, and one or more kinds of these monomers can be applied. Specifically, as hydrophilic monomers, for example, diacetone acrylamide, N, N-dimethyl acrylamide, N, N-dimethyl methacrylamide, N-ethyl methacrylamide,
N-ethyl acrylamide, N, N-diethyl acrylamide, N-propyl acrylamide, N-acryloyl pyrrolidine, N-acryloyl piperidine, N-acryloyl morpholine, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate,
Various methoxy polyethylene glycol (meth) acrylates, N-vinyl-2-pyrrolidone, etc. can be used.

Examples of the ionic monomer include N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylahanoethyl acrylate, N, N-dimethylaminopropyl methacrylamide, N, Examples thereof include amines such as N-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 such as glycidoxybutyl) acrylamide, N- (4-glycidoxybutyl) methacrylamide, N- (5-glycidoxybenzyl) acrylamide, and N- (6-glycidoxyhexyl) acrylamide. -Glycidoxyalkyl) (meth) acrylamide derivative, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
(Meth) acrylate derivatives such as lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl (meth) acrylate, olefins such as acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, ethylene, propylene and butene. Examples thereof include styrenes, divinylbenzene, α-methylstyrene, butadiene, isoprene and the like. The unsaturated monomer used for the copolymerization is generally in the range of 0 to 30% by weight, although it varies depending on the type of the unsaturated monomer and the combination thereof and cannot be generally stated.

Next, the above-mentioned monomers are polymerized to produce an acrylamide polymer. The polymerization method is preferably a radical polymerization method, and the polymerization solvent is water, alcohol, a polar solvent such as dimethylformamide. Applicable. The monomer concentration is 2 to 40% by weight, preferably 5 to 30% by weight. The polymerization initiator is not particularly limited as long as it is water-soluble. Specifically, examples of the peroxide type include ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl peroxide and the like. In this case, although it can be used alone, it can also be used as a redox polymerizing agent in combination with a reducing agent.

Examples of the reducing agent include sulfites, bisulfites, salts of low-order ions such as iron, copper and cobalt, N, N,
Organic amines such as N ', N'-tetramethylethylenediamine,
Further, reducing sugars such as aldose and ketose can be mentioned. 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 with respect to the monomer.
.About.0% by weight, preferably 0.1 to 8% by weight. Also,
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 the aqueous GPC column (for example, Sh
odex OHpak SB-800 HQ series) and it is in the range of 1,000 to 500,000 in pullulan conversion. When the weight average molecular weight exceeds 500,000, the viscosity of the aqueous solution becomes high, which hinders the handling.
If it is less than 000, there is a problem that fluidity is inferior.

In the Mannich reaction, the acrylamide polymer obtained above is reacted with formaldehyde and a dialkylamine or dialkanolamine.
Examples of dialkylamines include dimethylamine, diethylamine, dipropylamine, dibutylamine and the like, and examples of dialkanolamines include diethanolamine, dipropanolamine and the like. These secondary amine compounds may be used alone or in combination of two or more. As formaldehyde, either an aqueous solution (formalin) or paraformaldehyde may be used. The secondary amine compound is the number of moles of formaldehyde
Use 1.0 to 1.5 times.

In the present invention, the carboxylic acid amide is aminoalkylated by 1 to 50 mol% based on the total amount of the monomers of the acrylamide polymer by the Mannich reaction. The Mannich reaction depends on the aminoalkylation rate at a temperature condition of 20 to 80 ° C,
The reaction can be carried out by appropriately selecting the conditions from the reaction time of 10 minutes to 24 hours, but it is usually carried out at 40 to 60 ° C. for 20 minutes to 2 hours. The amount of the Mannich-modified acrylamide-based ampholytic polymer of the present invention added to the cement as solid content
0.05 to 2.5% by weight is suitable. If it is less than 0.05%, sufficient workability cannot be obtained, and if it exceeds 2.5%, it is economically disadvantageous. Furthermore, when the Mannich-modified acrylamide amphoteric polymer of the present invention is added to cement, a general admixture, admixture, that is, an air entraining agent, an early strengthening agent, a retarding agent, a waterproofing agent, a rust preventive, a water retention agent. , Colorants, preservatives, fiberglass, fly ash, blast furnace slag,
It is possible to use together with silica powder and the like. Furthermore, the Mannich-modified acrylamide-based amphoteric polymer of the present invention can be used as a water reducing agent for gypsum as well as concrete.

[0015]

EXAMPLES The present invention will be specifically described below by dividing it into production examples and application examples, but the present invention is not necessarily limited to the following examples. Unless otherwise specified,% is weight%
Shall mean. Production Example 1 A 1 liter stainless steel (SUS304) Dewar equipped with a stirrer, a thermometer, and a nitrogen gas inlet tube was charged with 40% acrylamide 280.
0g (1.58mol), 80% acrylic acid 60.80g (0.67mol),
An aqueous solution in which 429.2 g of deionized water and ion-exchanged water were mixed was adjusted to pH 4.5 with 10% caustic soda, adjusted to 20 ° C., and then added. After substituting by blowing nitrogen gas for 15 minutes, 10% ammonium persulfate aqueous solution and 10% sodium hydrogen sulfite aqueous solution were added with stirring to initiate polymerization. The internal temperature is
It rose to 75 ° C. Then, stirring was continued for 2 hours, and the weight average molecular weight of the obtained anionic polyacrylamide polymer was measured by a GPC column (Shodex OHpak KB-8 manufactured by Showa Denko KK).
It was 33,700 when measured using 0M * 2). This is referred to as polymer A. Then, the polymer A solution was diluted to 15%, and 350.0 g (0.74 mol (monomer unit)) of the solution was stirred with a stirrer,
Put it in a four-necked flask equipped with a reflux condenser and a thermometer and raise the temperature to 60 ° C. While stirring, 37% formalin 15.04g
(0.19 mol), 50% dimethylamine (21.66 g, 0.24 mol) and ion-exchanged water (47.78 g) were added, and the mixture was reacted for 1 hour. When the cation value of the reaction solution was examined, it was 2.9 meq./g.
This is designated as Polymer A-1.

Production Example 2 To 350.0 g of Polymer A (15%), 30.0% of 37% formalin was added.
8 (0.37 mol), 50% dimethylmine 43.32 g (0.48 mol)
Reaction was carried out in the same manner as in Production Example 1 except that
Polymer A-2 was obtained. The cation value was 5.4 meq./g.

Comparative Production Example 1 35% of Polymer A (15%) was added with 0.3% of 37% formalin.
10 g (1.23 × 10 ^-3 mol), 0.22 g (2.4% 50% dimethylamine)
Polymer A-3 was obtained by performing the reaction in the same manner as in Production Example 1 except that the amount was changed to 6 × 10 ⁻³ mol). Cation value is 0.1m
It was less than eq./g.

Comparative Production Example 2 A 1 liter stainless (SUS304) Dewar bottle equipped with a stirrer, a thermometer and a nitrogen gas inlet tube was charged with 40% acrylamide 396.
An aqueous solution prepared by mixing 0 g (2.23 mol), 80% acrylic acid 2.03 g (0.02 mol), and ion-exchanged water 372.0 g was adjusted to pH 4.5 with 10% caustic soda, and then adjusted to 20 ° C. before being charged. After substituting by blowing nitrogen gas for 15 minutes, 10% ammonium persulfate aqueous solution and 10% sodium hydrogen sulfite aqueous solution were added while stirring to initiate polymerization. Inner temperature is 77
It rose to ℃. Then, stirring was continued for 2 hours, and the weight average molecular weight of the obtained anionic polyacrylamide polymer was measured by a GPC column (Shodex OHpak KB-80M manufactured by Showa Denko KK).
* 2) was used to measure 18,500. This is referred to as polymer B. Then dilute the Polymer B solution to 15%,
350.0 g (0.74 mol (monomer unit)) was placed in a 1 liter 4-necked flask equipped with a stirrer, reflux condenser and thermometer.
The temperature is raised to 60 ° C and 37% formalin 15.04 g (0.
19 mol), 50% dimethylamine (21.66 g (0.24 mol)) and ion-exchanged water (47.7 g) were added and the reaction was carried out for 1 hour. When the cation value of the reaction solution was examined, it was 2.8 meq./g. This is designated as Polymer B-1.

The performance of the acrylamide polymers obtained in Examples and Comparative Examples as a cement water reducing agent was measured 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 and 2.5 g of acrylamide polymer
Was added and stirred for 3 minutes with a mortar mixer, and the flow value of the cement was measured. Table 1 shows the composition and flow value of the acrylamide polymer. The flow value of the cement paste when the polymer was not added was 150.

[0020]

[Table 1]

[0021]

EFFECTS OF THE INVENTION The acrylamide polymer of the present invention can greatly improve the water-reducing performance of cement as compared with a conventionally known copolymer of anionic monomer. The tertiary amino group introduced by the Mannich reaction is a functional group that exhibits cationicity in an acidic aqueous solution, and although there were many examples of application to a flocculant and an additive for papermaking, such a functional water reducing agent for cement was used. Until now, there was no idea to actively use the radical. 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 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 (1)

[Claims] 1. An α, β-unsaturated carboxylic acid amide having a weight average molecular weight of 1,000 to 500,000 (95 to 20).
Mol% and (2) α, β-unsaturated monocarboxylic acid (salt),
Acrylamide obtained by copolymerizing 5 to 80 mol% of one or more anionic monomer selected from α, β-unsaturated dicarboxylic acid (salt) and α, β-unsaturated sulfonic acid (salt) (1) Cement admixture containing (1) an amphoteric polymer obtained by reacting an α, β-unsaturated carboxylic acid amide in a Mannich reaction in an amount of 1 to 50 mol% based on the total monomer units. .