JPS63182243A - Manufacture of cement dispersion - 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] [Industrial application field] The present invention relates to a method for producing a cement dispersant.

More specifically, the present invention relates to a method for producing a cement dispersant in the form of a slurry in which gypsum, which is produced as a by-product in the neutralization process, is made into fine particles to stabilize dispersion when producing an aromatic sulfonic acid formalin condensate.

[Conventional technology]

The prior art will be explained by taking up naphthalene sulfonic acid formalin condensate salt, which is a representative example of aromatic sulfonic acid formalin condensate salt.

Conventionally, cement dispersants containing naphthalene sulfonic acid formalin condensate salt as an active ingredient have been produced by sulfonating naphthalene with sulfuric acid, condensing it with formaldehyde, and then converting the condensation product into an alkali metal hydroxide such as caustic potash or caustic soda. Alternatively, it can be produced by neutralizing with carbonate or the like. Prior to this neutralization, excess sulfuric acid is filtered off as gypsum, which is used as a homogeneous liquid dispersant in the cement field.

[Problem that the invention seeks to solve]

However, in the conventional manufacturing method, the filtration process consumes about 1/3 of the total process in terms of equipment, time, and labor, making it an economically disadvantageous manufacturing method.

The reason why this filtration step could not be eliminated is that the excess sulfuric acid could not be reduced from the viewpoint of the degree of sulfonation and degree of condensation. Furthermore, even if the sulfuric acid was made into mirabilite and water-solubilized, the product stability was poor due to its low solubility at low temperatures.Also, when it was made into gypsum, the gypsum could not be micronized into a stable slurry state, so it was difficult to make gypsum. It had to be removed by filtration.

[Means for solving problems]

As a result of intensive research to solve the above problems, the present inventors have developed a production method in which gypsum is made into fine particles until a stable slurry state is obtained. If neutralized with stirring with calcium hydroxide or calcium carbonate with an average particle size of 1- or less,
The present inventors have discovered that the gypsum produced by neutralization becomes fine particles of about 0.01 to 10 particles and can be stably dispersed in the reaction product as a slurry, leading to the completion of the present invention.

That is, the present invention provides a method for producing a cement dispersant containing an aromatic pentaaromatic sulfonic acid formalin condensate as an active ingredient by sulfonating a naphthalene hydrocarbon with sulfuric acid and condensing it with formaldehyde. To provide a method for producing a cement dispersant in which fine gypsum particles are stably dispersed, characterized in that sulfuric acid remaining in a liquid is neutralized with calcium hydroxide or calcium carbonate having an average particle size of 1 jna or less with stirring. It is.

[For production]

The neutralization conditions in the method of the present invention include factors such as the type of neutralizing agent, the particle size of the neutralizing agent, the order of neutralizing addition, the neutralization temperature, and stirring. Any calcium salt, oxide, or hydroxide can be used as the neutralizing agent, but there are problems with reaction by-products, economic efficiency,
Calcium hydroxide or calcium carbonate is used because it is easy to obtain fine particles. The particle size of the neutralizing agent is an average particle size of 1 μm or less. Although the order of neutralizing addition is not particularly limited, a method of dropping the neutralizing agent into the condensation product is preferred from the viewpoint of workability. The neutralization temperature is preferably on the low temperature side, but there is no noticeable difference from room temperature to about 80°C. The stronger the stirring, the more advantageous it is to forming fine particles, and a stirrer such as a homogenizer is preferable.

In the present invention, the neutralizing agent may be added as a powder, but it is preferably added as an aqueous slurry.

Examples of the naphthalene hydrocarbons used in the present invention include naphthalene and alkylnaphthalenes.

The method of the present invention can be similarly applied to a reaction product obtained by mixing lignin sulfonic acid with a sulfonated naphthalene hydrocarbon and cocondensing both with formaldehyde.

Although the cement dispersant of the present invention can be used as an acid,
Generally, it is preferable to use it in the salt form. Examples of the cations formed include sodium, potassium, complex salts of sodium and potassium, calcium, ammonium, alkanolamines, N-alkyl-substituted polyamines, polyethylene polyamines, polyethylene imines, and alkylene oxide adducts thereof.

To form a salt, sulfuric acid is neutralized with calcium hydroxide or calcium carbonate, and then the sulfonic acid in the reaction product is neutralized with the desired cation.

The cement dispersant produced according to the present invention is used as an aqueous solution after neutralization with sulfuric acid or sulfonic acid, or in the form of dried powder or granules.

Furthermore, the timing of adding the dispersant of the present invention to cement may be tri-blend with cement, dissolution in mixing water, or the start of kneading of a cement mixture, that is, at the same time as or immediately after pouring water into cement. It is possible to add it until the end of the process, and it is also possible to add it to the cement mixture once it has been kneaded. Further, the dispersant of the present invention can be added in its entirety at once, or added in several portions.

Although the cement dispersant according to the present invention has poor slump loss prevention performance, the slump loss prevention performance can be improved by adding a polymer component or a sustained release component to the cement dispersant according to the present invention. Effective ingredients include polycarboxylic acid or its salt or its granules, polycarboxylic acid anhydride or its granules, ligninsulfonic acid or its salts or its granules, water-soluble polymer or its granules', and melamine. Examples include sulfonic acid formalin high condensate or its salt or its granules, naphthalene sulfonic acid formalin condensate or salt granules, and the like.

〔Example〕

Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 5 and Comparative Examples 1 to 2 1.28 mol of 98% sulfuric acid was added to 1 mol of naphthalene,
A sulfonation reaction was carried out at a reaction temperature of 155°C to 160°C for 3 hours, followed by formaldehyde (35% formalin).
0.97 mol was added, and the condensation reaction was completed in 12 hours at a reaction temperature of 100°C. The composition of the resulting condensation product is that the sulfonic acid in the naphthalene sulfonic acid formalin condensate is 0.
．． 98 equivalents, and sulfuric acid was 0.56 equivalents.

Using the condensation product obtained under the same reaction conditions as above,
Sulfuric acid was neutralized using various neutralizing agents and neutralizing conditions shown in Table 1. The average particle size of the gypsum produced by neutralization is also shown in Table 1.

Table 1 Note) *1: Neutralization order -1: Place the condensation product in a container in advance, and add the neutralizing agent (3
0% water slurry) was added dropwise while stirring.

Order-2: Put a neutralizer (30% water slurry) in a container in advance,
The condensation product is added dropwise thereto while stirring.

Sequence-3: Drop the condensation product and neutralizer (30% water slurry) into the container simultaneously with stirring.

*2: Particle size measurement The particle size distribution of the gypsum slurry was measured using a Shimadzu centrifugal sedimentation type particle size distribution analyzer (SA-CF2), and the average particle size was determined.

Further, the sedimentation stability of the gypsum slurry obtained above was evaluated by the following method and is shown in Table 3.

Sedimentation Stability of Gypsum Slurry The naphthalene sulfonic acid formalin condensate salt containing gypsum fine particles was centrifuged, and the sedimentation stability was compared based on the proportion of gypsum remaining in the supernatant. Centrifugation conditions are 100g
The duration was 10 minutes.

Next, using the dispersant obtained in Table 1 and the commercially available sodium salt of naphthalene sulfonic acid formalin condensate, concrete was manufactured using the following materials, concrete formulation, and mixing method, and concrete dispersibility and strength development were tested. .

The test results are shown in Table 3.

Concrete dispersibility was measured by JIS A 1101 slump test and JIS A 1128 air volume test.

Moreover, the strength development property was determined by a compressive strength test according to JIS A 1108.

Materials used> Cement: Ordinary Portland cement (specific gravity 3.17) Fine aggregate: Ki-no-Yoto river sand (specific gravity 2.57) Coarse aggregate: Crushed stone from Takarazuka (specific gravity 2.59) Water: Concrete mix using tap water 〉 Table 2〈Concrete mixing method〉 Using a 1001 forced mixer, 50 Il of concrete was mixed at 20° C. for a total of 3 minutes. The order of adding the materials was: fine aggregate - cement -> water and dispersant, then kneaded for 2 minutes, then added the coarse aggregate, and then kneaded for another 1 minute. The amount of the dispersant added is 0.5% by weight of the effective content of naphthalene sulfonic acid formalin condensate salt versus cement.

<Steam curing> The manufactured concrete was immediately taken into a cylindrical form of φ10 x 20 cm and left at room temperature of 20° C. for 2 hours. Thereafter, the mold was transferred to a steam curing tank, and the temperature was raised to 65°C at a rate of 20°C/H. Thereafter, it was steam-cured at 65° C. for 3 hours and allowed to cool to room temperature. After 24 hours, the mold was removed and the compressive strength was measured. Other specimens were immersed in water at 20”C.
After curing for one day, a compressive strength test was conducted.

Table 3? NSF: Naphthalene sulfonic acid formalin condensate Na salt From Tables 1 and 3, the product of the present invention clearly has excellent product stability in the slurry state, and has the same effects as the comparative product in terms of dispersibility and strength development. I know that it will happen.

Claims (1)

[Claims] In a method for producing a cement dispersant containing an aromatic sulfonic acid formalin condensate as an active ingredient by sulfonating naphthalene hydrocarbons with sulfuric acid and condensing them with formaldehyde, the sulfuric acid remaining in the reaction solution after the condensation reaction is A method for producing a cement dispersant in which fine gypsum particles are stably dispersed, the method comprising neutralizing with calcium hydroxide or calcium carbonate having an average particle size of 1 μm or less while stirring.