JPH054846A - Cement admixture - Google Patents

Abstract

PURPOSE:To improve slump loss by using a cement admixture containing a co-condensate prepared by subjecting plural compound shown by specific general formulas and melamine and/or urea to addition co-condensation with formaldehyde. CONSTITUTION:Given amounts of (A) a compound shown by formula I and (B) a compound shown by formula II (R is H or lower alkyl; X is alkali metal) and (C) melamine shown by formula III (Y is H or CH2SO3X) and/or (D) urea shown by formula IV (at least two of Y are H) are weighed, mixed with water and adjusted to proper solid content concentration and pH. The solution is heated to about 80-90 deg.C, to which formalin corresponding to a given amount of formaldehyde is dripped. The compounds are subjected to addition co- condensation at pH 7-11 while stirring to give a co-condensate having a constituent molecular ratio of (A)/(B)/[(C)+(D)]=0.1-1.0/0.1-1.0/0.1-1.0 and 1,000-50,000 molecular weight. The co-condensate is used alone as a cement admixture or together with another admixture and mixed with cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture, and more particularly to a cement admixture such as a water reducing agent and a slump loss inhibitor used in cement compositions such as cement paste, mortar and concrete.

[0002]

2. Description of the Related Art Generally, a hydraulic cement composition gradually loses fluidity with the passage of mixing time (hereinafter, this phenomenon is referred to as slump loss), which causes a problem in workability in construction. That is, it is known that naphthalene-based and melamine-based admixtures that have been conventionally added as cement dispersants have a large slump loss.

As a countermeasure against this slump loss, a method of adding a curing retarder such as oxycarboxylic acid or lignin sulfonate has been proposed, but this method also delays the iron finishing time of the concrete and lowers the initial strength. In addition, the effect of preventing slump loss has not been sufficiently obtained, and a basic solution has not been reached.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a cement admixture, especially a concrete admixture, which improves the consistency of the cement composition and reduces slump loss. More specifically, when added to the cement composition, the fluidity of the cement composition is improved to increase the water reduction rate, and the cement composition can be transported for a long time without slump loss and pumped. An object is to provide a cement admixture that facilitates.

[0005]

[Means for solving the problems] Although the cause of slump loss is not clear, the admixture adsorbed on the cement particles (hereinafter referred to as a dispersant) is taken in by the chemical hydration reaction of the cement and dispersed. It is presumed that this is due to a decrease in the efficacy of.

[0006] Therefore, as a result of intensive studies, the present inventors have found that if the dispersant has a three-dimensional structure, the dispersant layer adsorbed on the cement particles becomes thicker and is incorporated into the cement hydrate. The inventors have found that the slump loss due to the retention of dispersibility is improved by delaying the heating time, and have completed the present invention.

That is, the present invention provides the following general formulas (A), (B),
And a cement admixture characterized by using as an essential component a cocondensate obtained by addition-cocondensing a three-component or four-component comprising the compounds represented by (C) and / or (D) with formaldehyde Is.

[0008]

[Chemical 3]

It is presumed that the above-mentioned three-component or four-component formaldehyde addition cocondensate used in the present invention has a three-dimensional molecular structure, which can reduce slump loss. That is, the addition reactivity of formaldehyde to the three or four components constituting the addition cocondensation product of the present invention is as follows: the number of methylol additions to phenolsulfonic acid is 2, phenol is 3, melamine is 6, and urea is 4 There is a possibility of Therefore, the co-condensates of methylol adducts for these three components are compared with conventional dispersants, such as naphthalene-based and melamine-based or phenol / sulfanilic acid co-condensates disclosed in JP-A-1-113419. In view of the large number of added methylol, there is a possibility of easily forming a multidimensional structure. Therefore, the general formula (A) of the present invention,
(B), and (C) and / or (D) three-component or four-component formaldehyde co-condensate, as is clear from the examples below, when used as a cement admixture, excellent It shows the effect of dispersibility and prevention of slump loss.

The cocondensate used in the present invention is obtained by addition-cocondensing the three or four components represented by the above general formulas (A), (B), and (C) and / or (D) with formaldehyde. R in the formula (A) means hydrogen or a lower alkyl group. As the lower alkyl group, a straight chain or branched chain alkyl group having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, pentyl and hexyl is desirable.

The formula (B) is a phenolsulfonic acid which may be substituted with a lower alkyl group as described above or an alkali metal salt thereof. The alkali metal salt is not particularly limited, but sodium salt and The potassium salt is preferred.

The compound of formula (C) is melamine or a sulfomethyl group-containing melamine. The compound of formula (D) is urea or a sulfomethyl group-containing urea. In the present invention, one or both of the compounds represented by the formulas (C) and (D) are used.

Of the compounds represented by the general formulas (C) and (D),
The compound having a sulfomethyl group can be obtained by introducing the sulfomethyl group into the corresponding raw material, but the introduction of the sulfomethyl group may be carried out at the stage of the monomer or the resulting cocondensate. Further, when it is carried out at the monomer stage, it may be carried out for each monomer,
It may be carried out for a mixture of raw material monomers including the monomers (A) and (B). Among these, this method is preferable because the physical properties of the co-condensate formed can be easily controlled by introducing a sulfonic acid group into each monomer. However, a sulfomethyl group may be introduced into the mixture of the monomers (A) to (D) in order to simplify the process.

The introduction of a sulfomethyl group into melamine or urea can be carried out using a known sulfonating agent such as sodium sulfite, sodium hydrogen sulfite, sodium pyrosulfite, etc. However, sodium pyrosulfite is used because of a small pH change in the system. preferable. The introduction of the sulfomethyl group may be complete or incomplete, but it is preferable to introduce the sulfomethyl group almost completely to the monomer from the viewpoint of controlling the physical properties of the cocondensate. When a sulfomethyl group is introduced into melamine, it is considered that formaldehyde is first added and condensed to the amino group of melamine to introduce a methylol group, and then the hydroxyl group is replaced with the sulfone group derived from the sulfonating agent. In this case, there are 6 possible bonding sites, but at least 2 of them are considered to be used for forming the cocondensate according to the present invention, and therefore introduction of a sulfomethyl group can be carried out within 4 positions per 1 melamine monomer. However, the present invention does not exclude either case.

The formaldehyde used to form the ternary or quaternary formaldehyde addition cocondensate is preferably an aqueous solution having a concentration of 30 to 40% by weight.

The addition co-condensation reaction of formaldehyde is suitably carried out in the range of pH 7 to 11 under basic conditions, but considering the efficiency of the methylol addition reaction and the condensation reaction, methylolation at pH 7.5 to pH 8.5 is carried out. And then pH 9.5
It is preferable to carry out the condensation reaction at pH 11 to pH 11, which is a two-step reaction by adjusting pH.

The formaldehyde addition co-condensate of the present invention contains the three components or four components of (A), (B), and (C) and / or (D) described above, so that the cement proposed heretofore has been proposed. A remarkable slump loss preventing effect is recognized as compared with the dispersant. In particular, the general formulas (A), (B), and (C)
And / or the constituent molar ratio of the compound represented by (D) is (A):
(B): [(C) + (D)] = 0.1 to 1.0: 0.1 to 1.0: 0.1
The range of ~ 1.0 shows excellent effect.

As an example of the cement admixture of the present invention, the three components of the compound of the general formula (A), the compound of the general formula (B) and the compound of the above formula (C) or (D) are used. The addition cocondensation product produced by using it is mentioned. In this case, melamine is used as the compound represented by formula (C), and urea is used as the compound represented by formula (D).

The co-condensate of the present invention has an average molecular weight of 1,000
The range of 50000 is preferable, and the range of 2000 to 20000 is more preferable.

The number of moles of the addition-condensation reaction of formaldehyde of the present invention is represented by the general formulas (A), (B), and (C) and / or
When the total number of moles of the compound represented by (D) is 1, the range of about 1 to 5 moles is preferable.

The method for producing the cocondensate according to the present invention is not particularly limited, and synthetic means usually used under basic conditions such as phenol, phenolsulfonic acid, (sulfomethyl group-containing) melamine and / or (sulfomethyl group-containing) Formalin (37% formaldehyde aqueous solution, the same below) was added dropwise to urea, or phenol, (sulfomethyl group-containing) melamine and / or (sulfomethyl group-containing) urea was administered after adding phenolsulfonic acid with formalin to methylol in advance. There is also a method such as addition-condensation, and any method is not limited in the scope of the reaction under basic conditions.

The standard method for producing the formaldehyde addition cocondensate of the present invention is shown below, but the present invention is not limited thereto.

A predetermined amount of phenol, sodium phenolsulfonate, melamine (sulfonic acid) and / or urea (sulfonic acid) and water are weighed and adjusted to pH (7 to 8.5) and solid content concentration, and then placed in a reaction vessel. It is charged, and formalin is added dropwise thereto at 80 to 90 ° C for 1 to 3 hours. After the dropping, the mixture is stirred under reflux for 3 to 30 hours. Then cooled to 30 ℃, pH 10 ~ 11
Adjust to. The cement admixture of the present invention can be obtained by further stirring and cooling under reflux for 3 to 10 hours.

The cement admixture of the present invention can also utilize an oxidation reaction, for example, the oxidation reaction shown in JP-A-60-11257 and JP-A-62-202850. There is no change in the dispersant that has many functional groups.

The cement admixture of the present invention is concrete,
Mortar, used as a dispersant for cement compositions such as cement paste, the addition method is preferably added at the same time as water injection for the purpose of preventing slump loss,
It is also possible to add it immediately after pouring water until the end of kneading, or to the cement mixture once kneaded. The cement admixture of the present invention can also be used as a high performance water reducing agent as a dispersant for secondary products.

When the cement admixture of the present invention is used, it may be used alone or in combination with a known cement admixture. In particular, even if the cement admixture has a large slump loss, the slump loss can be improved by using the cement admixture of the present invention together. The mixing ratio of the cement of the present invention and a known cement admixture can be arbitrarily selected according to the purpose, but if the mixing amount of the cement admixture of the present invention is 5% by weight or less, the slump loss improving effect is not expected so much.
Known cement admixtures that can be used in combination with the cement admixture of the present invention include naphthalene sulfonic acid formaldehyde condensate or a metal salt thereof, alkylnaphthalene sulfonic acid formaldehyde condensate or a metal salt thereof, melamine sulfonic acid formaldehyde condensate or a metal thereof. Examples thereof include salts, ligninsulfonic acid or a metal salt thereof, oxycarboxylic acid or a metal salt thereof, polycarboxylic acid or a metal salt thereof, and the like. Among them, it is preferable to use one or more selected from the group consisting of naphthalene sulfonic acid formaldehyde condensate or a metal salt thereof, melamine sulfonic acid formaldehyde condensate or a metal salt thereof, and lignin sulfonic acid or a metal salt thereof. When the cement admixture of the present invention and the above-mentioned conventionally known cement admixture are used in combination, they may be premixed and used, or may be added separately and used without any particular limitation.

Further, the cement admixture of the present invention is another known cement additive (material), for example, high performance water reducing agent, superplasticizer, AE agent, AE water reducing agent, retarder, early strengthening agent, accelerating agent. Agents, foaming agents, water retention agents, thickeners, waterproofing agents, rust preventives, coloring agents, antifungal agents, crack reducing agents, polymer emulsions, blast furnace slag, water-soluble polymers, expanding agents, fly ash, silica fume It is also possible to use in combination with a sustained release dispersant and a sustained release foaming agent.

[0028]

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

Preparation Example of Co-condensate (1) 0.5 mol of phenol, 1.0 mol of sodium phenolsulfonate and 0.5 mol of melamine were charged into a reaction vessel equipped with a stirrer, and 0.1 N sodium hydroxide aqueous solution and water were added to this solution. Is adjusted to pH 8.5 and the solids concentration is adjusted to 35% by weight. Next, the temperature of this solution is raised to 85 ° C and the solution of formalin (2.5 mol of formaldehyde) is stirred with stirring.
Is added and the reaction mixture is stirred under reflux for 10 hours. Then, cool to 30 ° C and adjust to pH 11 with 40% sodium hydroxide solution.
The mixture is stirred under reflux for 5 hours, cooled, and then water is added to adjust the solid content concentration to 25% by weight to obtain the cement admixture of the present invention. Table 1 below shows the contents of the cocondensates Nos. 1 to 7 of the present invention produced according to Production Example (1). still,
The number of moles of formalin in Table 1 means the number of moles of formaldehyde (the same applies to the production examples below).

[0030]

[Table 1]

Preparation Example of Cocondensate (2) Into a reaction vessel equipped with a stirrer, 1.0 mol of sodium metacresolsulfonate is charged, and a 0.1 N sodium hydroxide aqueous solution and water are added to adjust the solution to pH 8.5. next,
The solution is heated to 85 ° C., formalin (2.5 mol as formaldehyde) is added with stirring and the reaction mixture is stirred under reflux for 5 hours. Then, cool to 30 ° C, add 0.5 mol of metacresol and 0.5 mol of melamine, adjust to pH 11 with 40% sodium hydroxide aqueous solution, stir under reflux for 12 hours, and after cooling, add 1.0 mol of sodium sulfite and water. The cement admixture of the present invention is obtained by adjusting the solid content concentration to 25% by weight. Table 2 below shows the contents of the cocondensates Nos. 8 to 10 of the present invention produced according to Production Example (2).

[0032]

[Table 2]

Production Example of Cocondensate (3) Sodium phenolsulfonate was placed in a reaction vessel equipped with a stirrer.
Charge 1.0 mol and adjust the solution to pH 8.5 by adding 0.1 N aqueous sodium hydroxide solution and water. Next, the prepared solution is heated to 85 ° C and stirred with formalin.
2.5 mol are added and the reaction mixture is reacted under reflux for 5 hours (first step). Then, cool it to 30 ℃ and
Add 0.5 mol and 0.5 mol of melamine to adjust the pH to 11 with 40% aqueous sodium hydroxide solution, stir under reflux for 5 hours (second step), and after cooling, add 1.0 mol of sodium sulfite and water to adjust the solid content concentration. The cement admixture of the present invention is obtained by adjusting it to 25% by weight. Cement admixtures having different molecular weights can be obtained by changing the reaction time. Hereinafter, the cocondensate No. of the present invention produced according to Production Example (3).
Table 3 shows the contents of 11 to 13.

[0034]

[Table 3]

Preparation Example of Cocondensate (4) Phenol (1.0 mol), sodium phenolsulfonate (1.0 mol) and melamine (1.0 mol) were charged in a reaction vessel equipped with a stirrer, and 0.1 N aqueous sodium hydroxide solution and water were added to the mixture. The solution is adjusted to pH 8.5 and the solids concentration is adjusted to 35% by weight. Next, the prepared solution is heated to 85 ° C., formalin (3.3 mol as formaldehyde) is added with stirring, and the reaction mixture is stirred under reflux for 8 hours. Then, cool to 30 ° C and adjust the pH with 40% aqueous sodium hydroxide.
Adjust to 11 and stir under reflux for 12 hours. After stirring, add 2.5 mol of sodium pyrosulfite and stir formalin while stirring.
(3.0 mol as formaldehyde) is added and the reaction mixture is stirred under reflux for 2 hours. After cooling, water is added to adjust the solid content concentration to 25% by weight to obtain the cement admixture of the present invention. Table 4 below shows the contents of the cocondensates Nos. 14 to 16 of the present invention produced according to Production Example (4).

[0036]

[Table 4]

Production Example of Cocondensate (5) Phenol 0.9 mol and melamine 1.0 in a reaction vessel equipped with a stirrer.
Mole and formalin (2.8 mol as formaldehyde)
Is charged, and the melamine is completely dissolved by heating to 60 ° C, 1.5 mol of sodium pyrosulfite is added, and the mixture is further heated at 80 ° C for 2 hours. Then sodium phenolsulfonate
1.0 mol, 0.1 N sodium hydroxide aqueous solution and water were added, the prepared solution was heated to 95 ° C., formalin (3.0 mol as formaldehyde) was added with stirring, and the reaction mixture was stirred under reflux for 8 hours. . Then, the mixture is cooled to room temperature, adjusted to pH 11 with 40% aqueous sodium hydroxide solution, and stirred under reflux for 4 hours. After cooling to room temperature, the pH is adjusted to 9 with 20% sulfuric acid, and water is added so that the solid content concentration becomes 25% by weight to obtain a formalin cocondensate. Table 5 below shows the contents of the cocondensates Nos. 17 to 19 of the present invention produced according to Production Example (5).

[0038]

[Table 5]

Production Example (6) A cement admixture was prepared using 70% by weight of the cocondensate No. 1 obtained in Production Example 1 and 30% by weight of a naphthalene-based dispersant (Mighty 150; manufactured by Kao Corporation). (Invention product 20). A cement admixture was prepared using 50% by weight of the cocondensate No. 3 obtained in Production Example 3 and 50% by weight of a melamine-based dispersant (Melment; Showa Denko KK) (Invention product 21). ).

Evaluation as Cement Admixture-Concrete mix was as follows. W / C = 55% S / A = 49% C = 320kg / m ³ where C is cement, W is water, S is fine aggregate, and A is total aggregate. -The materials used are shown below. Cement = Central Portland Cement Fine aggregate = Kinokawa coarse aggregate = Takarazuka crushed stone ・ The mixer used was an inclining cylinder type and was kneaded for 3 minutes, then rotated for 4 minutes and stirred for 60 minutes. Table 6 shows the obtained evaluation results.

[0041]

[Table 6]

Note) * Addition amount:% solid content relative to cement. ** Comparative product A; naphthalene dispersant (Mighty 150: Kao
(Made by Co., Ltd.). ** Comparative product B; Melamine dispersant (Melment: Showa Denko
Manufactured by Co., Ltd.).

Evaluation results As shown in Table 6, the cement admixture of the present invention has a smaller difference between the slump value immediately after and 60 minutes later than the comparative product, and has an excellent water reducing effect and a remarkable effect in preventing slump loss. Indicates.

[0044]

By using the formaldehyde addition cocondensate with three or four components of the present invention as a cement admixture, the multi-component structure of the admixture has a thick admixture layer, and the admixture itself is a cement hydrate. It is estimated that the slump loss is improved by delaying the time taken into

Claims (5)

[Claims] 1. A cocondensate obtained by addition-cocondensing a three-component or a four-component comprising a compound represented by the following general formulas (A), (B), and (C) and / or (D) with formaldehyde. A cement admixture characterized by containing as an essential component. [Chemical 1] 2. A cement admixture comprising a compound represented by the following general formulas (A) and (B) and a three-component formaldehyde addition cocondensate consisting of melamine or urea as essential components. . [Chemical 2] 3. The constitutional molar ratio of the compounds represented by the general formulas (A), (B), and (C) and / or (D) is (A) :( B):
[(C) + (D)] = 0.1 to 1.0: 0.1 to 1.0: 0.1 to 1.0
The cement admixture according to claim 1, which is 4. A method for producing concrete, which comprises using the cement admixture according to claim 1 in combination with another cement admixture. 5. The cement admixture used in combination is one selected from the group consisting of a naphthalene sulfonic acid formaldehyde condensate or a metal salt thereof, a melamine sulfonic acid formaldehyde condensate or a metal salt thereof, and lignin sulfonic acid or a metal salt thereof. Alternatively, the method for producing concrete according to claim 4, wherein there are two or more kinds.