JPH0617256B2 - Water reducing agent for cement - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water reducing agent for use in a cement composition such as cement paste, mortar, concrete, etc., which has a particularly high water reducing property and has a fluidity with time. The present invention relates to a water-reducing agent for cement, which has less deterioration and has improved workability and workability.

[Conventional technology]

In recent years, various types of water reducing agents have been used for the purpose of improving physical properties such as workability improvement, strength and durability improvement, and cracking reduction in mortar construction and concrete construction. Agents are still required.

[Problems to be Solved by the Invention]

Conventionally, sulfonated melamine resin salt, polycarboxylic acid salt, naphthalene sulfonic acid formaldehyde high condensation product salt, lignin sulfonate, etc. have been used as a water reducing agent for cement, but the sulfonated melamine resin salt has a small water reducing effect. Requires a large amount of addition, polycarboxylic acid salt,
Although the effect of reducing water is great, increasing the amount of addition causes a significant delay in setting and, in some cases, insufficient curing. Naphthalenesulfonic acid formaldehyde highly condensate salt has a large water reducing effect, little delay in setting, and little air entrainment,
The fluidity of mortar and concrete decreases markedly with time. The lignin sulfonate has a large water-reducing effect, but has a problem in that it has a large amount of air mixed in, which adversely affects the physical properties of mortar and concrete.

Recently, a concrete admixture containing an aromatic aminosulfonic acid / phenol / formyaldehyde condensate has been developed (JP-A-1-13419). This admixture is said to improve the consistency of the cement composition and reduce fluidity changes such as slump loss over time, but further improvement is desired due to the large amount of residual monomers during condensation, etc. ing.

Therefore, it is possible to further improve the fluidity of the cement composition by reducing the residual monomer of the aromatic amino sulfonic acid-based admixture and imparting a polar group and stericity to the hydrophobic skeleton. A formaldehyde condensate of aminobenzene sulfonic acid was found and proposed (Japanese Patent Application No. 2-219435: Japanese Patent Application No. 1-227082 claims priority).

However, the formaldehyde condensate of this bisphenol compound / 4-aminobenzenesulfonic acid was not sufficient in the effect of preventing the deterioration of the fluidity over time in the long term.

[Means for Solving the Problems]

INDUSTRIAL APPLICABILITY The present invention reduces the residual monomer (aromatic aminosulfonic acid) of the aromatic aminosulfonic acid-based admixture, does not impair the effect of preventing the fluidity from decreasing over time, and further improves the fluidity of the cement composition. It was achieved as a result of diligent research aimed at that. The water reducing agent for cement of the present invention is mainly composed of a bisphenol compound / formaldehyde condensate of 4-aminobenzenesulfonic acid and a specific ligninsulfonate, and specifically, (a) 4-aminobenzenesulfonic acid. Or a salt thereof 100 parts by weight (b) Bisphenol compound or a salt thereof 20 to 150 parts by weight (c) Formaldehyde 20 to 65 parts by weight, which is produced by heating and condensing the bisphenol compound and 4-aminobenzene. 80-20 parts by weight of formaldehyde condensate of sulfonic acid and 0.2% per unit of lignin sulfonate or phenylpropane obtained by ultrafiltration treatment of sulfite pulp effluent until the reducing sugar content is 5% or less.
The present invention relates to a water-reducing agent for cement, which comprises, as a main component, 20 to 80 parts by weight of a lignin sulfonate having a carboxyl group of 0.1 mol or more and a sulfone group of 0.10 mol or more.

The bisphenol compound used in the present invention for producing a formaldehyde condensate of bisphenol compound / 4-aminobenzenesulfonic acid has the general formula The compound represented by Is preferred.

In order to produce a condensate, which is one of the main components of the water reducing agent of the present invention, it is desirable to carry out the condensation at the above-mentioned specific ratio, and if it is out of this range, the water reducing property, the fluidity and the aging property will be deteriorated. .

The weight average molecular weight of the condensate is in the range of 10,000 to 50,000 as measured by gel permeation chromatography (GPC), and if it deviates from this range, the fluidity-improving effect decreases.

The ultrafiltration-treated lignin sulfonate, which is another component of the water-reducing agent of the present invention, is purified to 5% or less of reducing sugars in the sulfite pulp effluent. The fractionation film in the ultra treatment is 1,000 to 30,000, preferably 5,000 to 20,000.

Further, a lignin sulfonate containing 0.20 mol or more of carboxyl groups and 0.10 mol or more of sulfo groups per phenylpropane unit reduces the sulfone group by oxidizing the sulfite pulp effluent with alkali as shown in Japanese Patent Publication No. 56-40106. Alternatively, it can be produced by sulfomethylating thiolignin in the kraft pulp effluent and introducing a sulfone group.

Here, the formaldehyde condensate of bisphenol compound and 4-aminobenzene sulfonic acid alone is not sufficient for long-term fluidity, and the use of the specific lignin sulfonate as described above in combination produces a satisfactory effect for the first time. To be The ratio is the former: the latter = 80 to 20:20 to 80 (parts by weight), and if it is out of this range, the effect is remarkably reduced.

[Action]

The condensate used in the present invention has a remarkable effect of improving fluidity as compared with the formaldehyde condensate of 4-aminobenzenesulfonic acid and phenol (hereinafter abbreviated as A compound) disclosed in JP-A 1-113419. This is based on the following reasons in addition to the structural contribution of bisphenol compounds.

After the condensation reaction of the compound A, about 10% of 4-aminobenzenesulfonic acid remains as a residual monomer, but this is likely to cause phenol to form a homopolymer, and as a result, unreacted 4-aminobenzenesulfonic acid tends to remain. It seems to be because.

In this way, the condensation reaction of the A compound using phenol is referred to as the first step (reaction in weak alkali) and the second step (reaction in strong alkali) due to the side reaction and the nature of phenol itself. It is necessary to use complicated means.

On the other hand, in the case of a formaldehyde condensate of a 4-aminobenzenesulfonic acid-bisphenol compound, which is the main component of the water reducing agent of the present invention, the residual monomer is reduced to about 1/3 of that of the compound A. It is considered that this is because the bisphenol compound of the present invention is poorly soluble in water and alkali, and the formation of a homopolymer as a side reaction is less likely to occur as compared with phenol. Further, in the case of the present invention using a bisphenol compound, there is a feature that it is not necessary to use a complicated reaction means unlike the case of the A compound using phenol.

The water reducing agent for cement of the present invention is 0.01 to 2.0% of the cement.
It is preferably used in a proportion of 0.1 to 0.6%. If the blending amount is too small, the expected effect cannot be obtained, and if it is too large, the cement is excessively dispersed and a separation phenomenon occurs, which is not preferable.

The cement to which the present invention is applied includes ordinary Portland cement, early-hardening cement, ultra-fast-hardening cement, blast furnace cement,
Medium heat cement, fly ash cement, sulfate resistant cement, etc. are used. Further, the water reducing agent for cement of the present invention can be used in combination with other cement additives such as water reducing agent, air entraining agent, setting retarder, waterproofing agent, expanding agent, silica fume, stone powder and the like.

〔Example〕

 The present invention will be described below with reference to examples.

Production Example 1 A reaction container was charged with a predetermined amount of the following substances.

(I) 4-aminobenzenesulfonic acid 173.20 g (1 mol) (II) 2,2-bis (4-hydroxyphenyl) propane 114.15 g (0.5 mol) (III) 95% NaOH 42.11 g (1 mol) water 768.74 g Next, add 35% formaldehyde aqueous solution (IV) to this solid-liquid suspension.
205.72 g (2 mol) was added dropwise under reflux, and the resulting reaction mixture was stirred for 10 hours to obtain an aqueous condensate solution.

The weight-average molecular weight (▲ ▼) of the obtained condensate and the amount of unreacted 4-aminobenzenesulfonic acid were 24,950 and 2.
8% (vs solids).

The weight average molecular weight was measured by gel permeation chromatography (GPC) and converted by pullulan standard.
The unreacted 4-aminobenzenesulfonic acid was obtained from the area ratio of a GPC differential refractometer.

Production Example 2-4 A condensate was obtained in the same manner as in Production Example 1 except that the bisphenol compound was changed.

The results are shown in Table 1.

Production Example 5 Sulfite pulp effluent was air-oxidized under alkaline conditions, precipitated with sulfuric acid, washed with water, neutralized with sodium hydroxide, and lignin sulfone containing 0.3 mol of sulfone groups and 0.4 mol of carboxyl groups per phenylpropane unit. The acid salt was obtained.

Production Example 6 Sulfite pulp effluent was concentrated and purified with an ultrafiltration membrane (Bioengineering KK, trade name G05T (fraction molecular weight 5,000). Reducing saccharide of lignin sulfonate thus obtained was 3.2%. (Vs. solid content).

Example 1 The lignin sulfonate produced in Production Example 5 and the condensate produced in Production Example 1 were mixed at 50:50 (solid content ratio) to obtain Product 1 of the present invention.

Example 2 The lignin sulfonate produced in Production Example 6 and the condensate produced in Production Example 1 were mixed at 50:50 (solid content ratio) to obtain Product 2 of the present invention.

Example 3 The condensate produced in Production Example 2 and the lignin sulfonate produced in Production Example 5 were mixed at 60:40 (solid content ratio),
The product 3 of the present invention was obtained.

Example 4 The condensate produced in Production Example 2 and the lignin sulfonate produced in Production Example 6 were mixed at 40:60 (solid content ratio),
The present invention product 4 was obtained.

Test Example The materials used and the composition of concrete are as follows.

Cement (C): Normal Portland cement Fine aggregate (S): Land sand from Kisarazu (specific gravity 2.59, FM2.40) Coarse aggregate (G): Crushed stone from Yamaguchi (specific gravity 2.70, FM6.75) Water (W): Tap water The water reducing agents of Examples 1 to 4 were added to the formulations shown in Table 2 in a 100 mixer and kneaded for 3 minutes. Immediately after that, the air content of each slump was measured after 30, 60, 90 and 120 minutes. The concrete slump and the amount of air were measured in accordance with JIS. For comparison, the same procedure was performed using the water reducing agent composed of the condensate obtained in Production Examples 1 to 4, and the results of Comparative Examples 1 to 4 were obtained.

The measurement results are shown in Table 3, and it can be seen that the product of the present invention has better fluidity retention than the conventional product.

[Effect of the Invention] By using the product of the present invention, it is possible to obtain a cement composition having less change in fluidity over time than conventional cement additives.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08L 61/22 LNH 8215-4J

Claims (3)

[Claims] 1. A bisphenol-4-condensation product of 4-aminobenzenesulfonic acid or a salt thereof, a bisphenol compound represented by the following general formula (1) or a salt thereof, and formaldehyde, which are condensed by initiating a reaction in an alkaline solid-liquid state.
80 to 20 parts by weight of aminobenzene sulfonic acid condensate, and lignin sulfonate obtained by subjecting sulfite pulp effluent to ultrafiltration until the content of reducing sugars is 5% or less and / or 0.20 mol or more of carboxyl groups per phenylpropane unit. 0.
A water-reducing agent for cement, which comprises, as a main component, 20 to 80 parts by weight of a lignin sulfonate containing 10 mol or more sulfone groups. General formula (1) Where X is Or represents -O-. 2. 100 parts by weight of 4-aminobenzenesulfonic acid or a salt thereof, 20 to 50 parts by weight of a bisphenol compound represented by the general formula (1) or a salt thereof and 20 to 65 parts by weight of formaldehyde in an alkaline solid-liquid state. The water reducing agent for cement according to claim 1, wherein the bisphenol-4-aminobenzenesulfonic acid condensate produced by initiating the reaction and condensing is used. 3. The weight average molecular weight of the condensate is 10,000 to 50,000.
The water reducing agent for cement according to claim 1 or 2.