JPS6033239A - Cement dispersing agent - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cement dispersant, and more particularly to a water reducing agent and a sulfur PS inhibitor used in cement compositions such as cement paste, mortar, and concrete.

Various types of cement dispersants are known, but representative ones include β-naphthalenesulfonic acid formaldehyde condensed metal salt (hereinafter abbreviated as β-NSF), melamine sulfonic acid formaldehyde condensed metal salt, and lignin. Sulfonic acid (hereinafter abbreviated as LS) salts are known. These are used when kneading cement compositions, thereby reducing the amount of water used and improving workability. However, it is known that all of these known dispersants have a common drawback of a significant decrease in fluidity over time (hereinafter referred to as slump loss).

In general, in hydraulic cement compositions, after mixing, chemical and physical aggregation of cement particles progresses over time, gradually losing fluidity and causing problems in workability during construction. In particular, concrete with the addition of a high-performance water reducer such as β-NSF is significantly lower than when no concrete admixture is used or when conventional admixtures such as AH agent, water reducer, and Ag water reducer are used. , the slump loss is significant due to the high rate of water reduction.

When such a slump occurs, for example, when pumping cement composition at a concrete factory, etc., the pumping is temporarily interrupted due to product shortage or trouble, and then when the pumping is resumed, the pumping pressure Accidents such as a sudden increase in the amount of cement and blockage of the pump may occur.Furthermore, if compaction or other forming is delayed for any reason after pouring the cement composition, problems such as non-filling may occur. .

For ready-mixed concrete, slump loss occurs during the process from the concrete manufacturing plant to the pouring site, resulting in a significant decrease in work efficiency, blockage of pumps, and
This may cause problems such as non-filling during JAm. The cause of such slump loss is not clear, but after the cement particles in the cement paste come into contact with water, they undergo coagulation due to chemical water phase reactions and/or physical aggregation due to interparticle attraction. However, it is thought that this is because the fluidity of the cement paste and, by extension, the hydraulic cement composition decreases over time. In particular, when adding a concrete water reducing agent (cement dispersant) such as β-NSF or L8, the water reducing agent adsorbs to the cement particles, increases the zeta potential of the cement particles, and uses its electrical repulsion to disperse the cement particles. can improve the fluidity of hydraulic cement compositions (Hanbu, Concrete Engineering Vol. 14, No. 3, 1).
(See pages 2 to 19, March 1976 issue), over time, water reducing agents are stored in the precipitated minerals in the aqueous phase of cement, and the electrical repulsion becomes ineffective, causing a decline in fluidity (it is thought that Therefore, if a water reducing agent that disperses cement particles can be continuously supplied in some way, the cement particles can be dispersed in the form of primary particles, and slump of the hydraulic cement composition can be prevented. It is thought that it is possible to do so.

The following methods have been discovered as countermeasures against slump loss based on this idea. That is, 1) Make the admixture for concrete into powder or granules, or confine it in a carrier and gradually release the active ingredient into the system to maintain its effect (for example, JP-A-54-159929 @) V. Mixed phase for concrete The agent is repeatedly added to the hydraulic cement composition by mechanical force (for example, Japanese Patent Publication No. 51-15
No. 856@i) etc.

However, in the case of υ, although measures to prevent slump loss are well accepted, cement dispersants remain locally in the cement mixture even after the purpose of maintaining slump has ended, causing local bleeding. , and even leave negative effects such as a decrease in frequency. Measures to prevent slump loss are also accepted in O, but if the concrete after being discharged from the mixer is in the pressure-feeding piping or formwork, it becomes difficult to add concrete admixtures.

In addition, as a measure to prevent slump loss, in order to suppress chemical coagulation of cement particles, substances such as oxycarboxylate or lignin sulfonate are added or used in combination to delay the initial hydration reaction of cement (for example, Public 1@5
2-24555, Japanese Patent Publication No. 52-15855, and Japanese Patent Application Laid-Open No. 54-17918), it has also been found that chemical coagulation of cement particles can be suppressed to some extent by this method, but the effect is not sufficient. Not. In addition, in order to increase the effect, the thickness of violet is added (if this happens, the initial slump will become too large and there is a risk of causing aggregate separation, causing an increase in setting time and causing a major problem in breathing and initial strength.

As described above, each method has its own drawbacks and poses practical problems.

The Ministry of the Invention and others have developed a method in which the dispersant is not in the form of a powder or granules as in the above-mentioned method. The present invention was completed by perfecting the method of preventing slump loss using a concrete admixture.

That is, the present invention provides 0.1 per 7talene Ra of carboxyl groups obtained by oxidizing a formalin condensate or a formalin cocondensate of naphthalene sulfone m and/or an alkylnaphthalene sulfonic acid or a salt thereof by an oxidation reaction.
The object of the present invention is to provide a slump loss-preventing m-cement dispersant, which contains as an essential component a compound having 1.0@.

The 7-lene sulfonic acid and alkylnaphthalene sulfonic acid of the present invention may also include creosote oil, naphthalene oil, components such as pitch generated in the process of coking coal, or sulfonated products such as coal liquefied oil that contain these components. used. Further, a partially unsulfonated compound may be included as naphthalene sulfonic acid or alkylnaphthalene/L'*7H. Further, for the oxidation reaction, it is preferable to contain an alkylnaphthalene sulfonic acid such as methylnaphthalene sulfonic acid as a component.

The oxidation reactant can be obtained by a known method. For example, oxidation reactions using gold JIi oxides such as permanganates, oxygen or g! Oxidation by air, oxygen as an alkali catalyst or by sudden air. Examples include oxidation, oxidation reactions using water-soluble -A#R compounds such as crushed hydrogen chloride, and persulfates such as ammonium persulfate. The structure of these oxidation reaction products is not clear, and various bonds are oxidized depending on the oxidation reaction conditions. Typical reaction formats among these reactions include oxidation of naphthalene rings, oxidation of methyl 4-yl groups generated during formalin condensation, and oxidation of alkyl groups such as methyl groups bonded to naphthalene rings. In particular, oxidation of naphthalene rings is carried out on an industrial scale to produce heptars from naphthalene. Through these oxidation reactions, 0.1 to 1.0
It is possible to obtain unique compounds. If the number of carboxyl groups is less than 0.111i1 per naphthalene ring,
It is not effective in preventing slump loss, and if the number exceeds 1.0, condensation M formation becomes significant, which is not preferable.The reason why the compound of the present invention is extremely effective as a cement dispersant for preventing slump loss is not clear, but the following It can be thought of as follows.

That is, black ink is known in which the formalin condensate or formalin cocondensate as a component of the compound of the present invention exhibits high dispersibility, and the carboxyl group contained in the compound of the present invention is effectively adsorbed to cement particles. It is believed that the sulfone groups present in the compound increase the charge of the cement particles outward and prevent slump loss due to charge storage due to water phase reactions of the cement.

Although the cement dispersant of the present invention can be used as an acid, it is generally preferable to use it in the form of a salt. The cations formed include Na, K.

Examples include Oa*NH4, alkanolamine, N-alkyl substituted polyamine, ethylenedi7mine, polyethyleneboriaine-polyethyleneimine, or a fullkylene oxide adduct thereof.

The cement dispersant of the present invention is added at a solid content of 0.2% by weight based on the cement of the hydraulic cement composition.
5 to 2.5 is good. If it is less than 0.25%, sufficient dispersion effect and slump prevention effect on cement particles cannot be obtained. Moreover, if it exceeds 2.5%, it may be economically disadvantageous or the dispersion of cement particles may become excessive, causing pleating or paste separation.

The cement dispersant according to the present invention is most preferably added to the hydraulic cement composition in the form of a hydrolyzed liquid, but the effect of preventing slump loss can also be obtained in the form of powder or granules.

Also, when adding it, mix the dispersant and dissolve it in water. s′
The dispersant of the present invention can be added at the same time as kneading water, added to the kneaded hydraulic cement composition, or added to the cement composition in the form of powder. It is also possible to add it.

In addition to the cement dispersant of the present invention, other cement dispersants, water bathing polymer compounds, etc. can also be used in combination.

Other cement dispersants include formalin condensate of naphthalene sulfonic acid, lignin sulfonate, formalin condensate of melamine sulfonic acid, polycarboxylate, etc., which are trade names of Mighty 150 (manufactured by Kako Soup Co., Ltd.). ,
Among these, formalin condensates of naphthalenesulfonic acid and ligninsulfonates are particularly preferred. In addition, as the lignin sulfonate, Chemical Adn+
1xtures for 0oncreta (M, R,
Pure lignosulfon with analytical values and properties close to the molecular basin distribution as described on pages 5 to 9 of RIXOMJ&F, N, 5pon Ltd.
ate is good.

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

The concrete formulations and materials used in Examples and Comparative Examples are shown in Table 1 below.

Table 81 Cement (Oj: Ordinary Portland Cement (Onoda Cement) Fine Aggregate (S): Kinoki Sand (Ratio, i2.58.FM 2
．． 91) Coarse aggregate (G): Crushed stone from Takarazuka (specific gravity 2.61,
1M6.98) Water (W) (W material Mighty Ag-05 (manufactured by Kako Soap Co., Ltd. part name)
The appropriate amount of the cement dispersant was added, and the concrete was mixed using either of the following methods 1 and 2.

Method 1: Knead the cement dispersant in advance, dissolve in water, and knead for 40 minutes in a tilting mixer at 25C, using the concrete mixture shown in Table 1, and further kneading at a rotation speed of 2 rpm for the required time. Next, we measured changes in slump and total volume over time. Measurements of slump, total air volume, compressive strength, and sampling of strength specimens were all carried out in accordance with JIS.

Method 2: The same procedure as Method 1 was carried out except that the cement dispersant was added at the same time as the mixing water.

Reference Shiosu naphthalene sulfonic acid (20811), methylnanthalene sulfonic acid (45,9), 98% concentrated sulfuric acid (10I),
Water (50,9) was placed in a 5ooHi flask and heated to 80C. Next, at 80-90C, 37% formalin (
140&) was added dropwise for 0.5 hour, then 90~10
The reaction was carried out at 0C for 8 hours to obtain a co-condensate. Thereafter, the mixture was made slightly alkaline with sodium hydroxide, potassium permanganate (6 sl) was added, and the mixture was reacted at 50C for 3 hours and filtered according to a conventional method to obtain the product of the present invention. The number of carboxyl groups was 0.2 (per Nanthalene R). Table 2 shows the composition of the product of the present invention obtained in the same manner.

Table 2 Examples 1 to 9 and Comparative Examples 1 to 4 A mixing test into concrete was conducted using the products of the present invention obtained in the above reference examples and comparative products such as commercially available cement dispersants as dispersants. Test conditions are shown in Table 3. In addition, the results of mixing tests into concrete are shown in Tables 4 and 5.

Table 3 (Edo 1 to cement) vrt% (solid content) *2 Nafculensulfonic acid formalin condensate manufactured by Hanadama Soap Co., Ltd. *3 Pure l having the properties described in the detailed description section
ignosulfonata*4 JP-A-51-451
The reaction was carried out in the same manner as in the Example of Publication No. 23. That is, the molar ratio of naphthalenecarboxylic acid sulfate (2529) to naphthalenecarboxylic acid (8'52,!9)C = 2/8
A reaction product obtained by neutralizing the formalin condensate of : with caustic soda.

Table 4 (Note: Slump residual rate = (slump after a certain period of time)
/ (Initial slump) x 10 units (%) Table 5 (Note 2) Standard curing (ky/Sono 2) From the results in Tables 4 and 5, the product of the present invention was extremely superior in terms of slump survival rate. It is clear that it has an effect.

Claims (1)

[Scope of Claims] 1. Obtained by oxidizing a formalin condensate or formalin cocondensate of naphthalene sulfonic acid and/or alkylnaphthalene sulfonic acid or a salt thereof by an oxidation reaction.
A cement dispersant for preventing slump loss, which contains as an essential component a compound having 0.1 to 1.0 carboxyl groups per naphthalene ring. Claim 1, wherein the oxidation reaction is a reaction using a metal oxide. A cement dispersant that prevents slump loss. 3. The slump loss preventing cement dispersant according to claim 1, wherein the rR reaction is a reaction using oxygen or air using a metal or a metal salt as a catalyst. 4. The slump loss preventing cement dispersant according to claim 1, wherein the oxidation reaction is a reaction using hydrogen peroxide or a water bath peroxide.