JPH0660041B2 - 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 little deterioration and has improved workability and workability.

[Conventional technology]

In recent years, it has been used from various water reducing agents 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 salts, polycarboxylic acid salts, naphthalene sulfonic acid formaldehyde highly condensed salts, lignin sulfonates, etc. have been used as water reducing agents for cement, but sulfonated melamine resin salts have a small water reducing effect. Requires a large amount of addition,
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. The naphthalene sulfonic 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 / formaldehyde condensate has been developed (JP-A 1-113419). This admixture is said to improve the consistency of the cement composition and reduce the fluidity change such as slump loss with the passage of time, but further improvement such as a large amount of residual monomer at the time of condensation is desired. ing.

[Means for Solving the Problems]

INDUSTRIAL APPLICABILITY The present invention reduces the residual monomer (aromatic aminosulfonic acid) of an aromatic aminosulfonic acid-based admixture, and also imparts a polar group and a steric property to the hydrophobic skeleton, thereby preventing the fluidity of the compound from deteriorating with time. The present invention has been achieved as a result of intensive research aimed at further improving the fluidity of the cement composition without impairing it. The water-reducing agent for cement of the present invention is (a) 4-aminobenzenesulfonic acid (sulfanilic 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 The main component is a formaldehyde condensate of a bisphenol compound / 4-aminobenzenesulfonic acid, which is produced by heating and condensing the above under aqueous conditions.

The bisphenol compound used in the present invention has the general formula Is a compound represented by Is used.

In order to produce the condensate which is the main component of the water reducing agent of the present invention, it is necessary 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.

In this condensation reaction, the influence of alkali is large, and the addition ratio of alkali is 0.90 to 1.30 in terms of molar ratio to 4-aminobenzenesulfonic acid when bisphenol compound / 4-aminobenzenesulfonic acid = 0.5 / 1. preferable.
If it goes out of this range, the amount of residual monomer (unreacted 4-aminobenzenesulfonic acid) will rapidly increase.

The weight average molecular weight of the condensate, which is the main component of the water reducing agent of the present invention, is in the range of 10,000 to 50,000 as measured by gel permeation chromatography (GPC).

[Work]

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.

This is probably because phenol easily forms a homopolymer, and as a result, unreacted 4-aminobenzenesulfonic acid is likely to exist.

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 4-aminobenzenesulfonic acid-bisphenol compound which is the main component of the water reducing agent of the present invention, the residual monomer is 1
It decreases to about / 3. 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.

Cement includes normal Portland cement, early strength cement, ultra early strength cement, blast furnace cement, moderate heat cement,
Fly ash cement, sulfate resistant cement, etc. are used. It can also be used in combination with other cement additives such as water reducing agents, air entraining agents, setting retarders, waterproofing agents, expanding agents, silica fume, stone powder and the like.

〔Example〕

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

Example 1 A reactor was charged with the following substances in predetermined amounts.

(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, to this solid-liquid suspension, (IV) 35% formaldehyde aqueous solution 171.43 g (2 mol) was added dropwise under reflux. Then, the resulting reaction mixture was stirred for 10 hours to obtain a transparent condensate aqueous solution.

The weight-average molecular weight of the obtained condensate () and the amount of unreacted 4-aminobenzenesulfonic acid were 24,950 and 2.8%, respectively.
(Vs. solid content).

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. These are shown in Table-1.

Examples 2 to 6 The reaction was carried out by changing the molar ratios of 4-aminobenzenesulfonic acid (I) (II) (III) (IV), 2,2-bis (4-hydroxyphenyl) propane, NaOH and formaldehyde. A condensate was obtained in the same manner as in Example 1.

The results are shown in Table-1.

Examples 7 to 10 A predetermined amount of the following four kinds of substances was charged into a reaction vessel.

(I) 4-aminobenzenesulfonic acid 173.20 g (1 mol) (II) 4,4'-dihydroxydiphenylmethane 100.12 g (0.5 mol) (III) 95% NaOH 42.11 g (1 mol) water 736.00 g Next solid 35% formaldehyde aqueous solution 171.
43 g (2 mol) were added under reflux and the reaction mixture was refluxed.
After stirring for 10 hours, an aqueous solution of a condensate was obtained.

The weight average molecular weight () and the residual 4-aminobenzenesulfonic acid content of the obtained condensate were 29,865 and 3.6% (relative to solid content), respectively.

The weight average molecular weight was measured by gel permeation chromatography and converted by pullulan standard. The residual 4-aminobenzenesulfonic acid was obtained from the area ratio of the gel permeation chromatography using a differential refractometer. The results are shown in Table 2.

Further, the bisphenol compounds were changed as shown in Table 2 and the same procedure was carried out to obtain Examples 8 to 11.

The results are also shown in Table 2.

Comparative Example 1 A reaction vessel was mixed with a predetermined amount of the following four kinds of substances, and 0.1N
The pH was adjusted to 8.1 with aqueous NaOH solution.

(I) 4-Aminobenzenesulfonic acid 173.20 g (1 mol) (II) Phenol 94.10 g (1 mol) (III) 95% NaOH 42.11 g (1 mol) Water 721.97 g Next, in this aqueous solution, (IV) 35 % Formaldehyde aqueous solution
171.43 g (2 mol) was added under reflux, and the mixture was stirred under reflux for 7.5 hours (first step).

The mixture was cooled to room temperature, pH 11.0 with 20% NaOH aqueous solution.
The mixture was refluxed for 3 hours (second step) to obtain a condensate.

The weight average molecular weight () of the obtained condensate and the amount of residual 4-aminobenzenesulfonic acid were 23,375 and 11.8% (relative to solid content), respectively.

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

Comparative Examples 2 to 4 Condensates were obtained in the same manner as in Comparative Example 1 by changing the respective molar ratios of 4-aminobenzenesulfonic acid (I) (II) (IV), phenol and formaldehyde as reaction conditions.

The results are shown in Table-3.

[Test Example] Concrete test The consistency of the concrete containing the water reducing agent of the present invention was compared with the consistency of the concrete containing the water reducing agent of the comparative example, and the slump loss (temporal change in fluidity) of the concrete was compared. .

The formulation is shown in Table 4.

For concrete, cement, aggregate, and water or water containing a water-reducing agent were kneaded in a 100-port tilting mixer for 3 minutes, and immediately after, 30 and 60 minutes later, slump was measured. The slump of concrete and the amount of air were measured according to JIS.

The measurement results are shown in Table 5, and the product of the present invention (Example) can obtain the target slump with a smaller addition rate than that of the conventional water reducing agent (Comparative Example). It shows that it is superior to.

[Effects of the Invention] By using the product of the present invention, it is possible to obtain a cement composition having a predetermined fluidity with a smaller addition amount than the conventional cement admixture, and moreover, the fluidity is less likely to change with time. .

Claims (4)

[Claims] 1. A water-reducing agent for cement comprising a formaldehyde condensate of 4-aminobenzenesulfonic acid or a salt thereof and a bisphenol compound or a salt thereof as a main component. 2. A bisphenol compound represented by the following general formula: The water reducing agent for cement according to claim 1, which is a bisphenol compound represented by: 3. 4-Aminobenzenesulfonic acid or a salt thereof
100 parts by weight and bisphenol compound or its salt 20〜
The water reducing agent for cement according to claim 1 or 2, which contains a bisphenol compound / 4-aminobenzenesulfonic acid condensate produced by condensing 150 parts by weight of formaldehyde and 20 to 65 parts by weight of formaldehyde. 4. The water reducing agent for cement according to claim 1, wherein the condensate has a molecular weight of 10,000 to 50,000.