JPH04349159A - Production of cement dispersant - Google Patents

Abstract

PURPOSE:To provide a production of a cement dispersant. CONSTITUTION:This cement dispersant is produced by the following processes (1) and (2) in the production of the alkali metal salt of a naphthalenesulfonic acid-formalin condensate. (1) One mol of naphthalene is sulfonated with 1.12-1.17 mols of fuming sulfuric acid (expressed in terms of sulfuric acid). (2) Neutralization is carried out with the double salt consisting of one mol of sodium salt and 0.8-1.2 mols of potassium salt. As a result, the process for producing the dispersant is drastically simplified, and the cost is reduced. The dispersant has excellent dispersibility and is widely used in the field of ready-mixed cement, secondary products, etc.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention relates to a method for producing a cement dispersant. The agent solution is related to direct neutralization of a naphthalene sulfonic acid formalin condensate with an alkali salt, without crystallization of an inorganic salt even at 0°C. The cement dispersant obtained by the production method of the present invention can be effectively used as an organic or inorganic powder dispersant for coal, pigments, dyes, etc. in addition to cement. [Prior Art and Problems to be Solved by the Invention] To specifically explain the conventional production of naphthalene sulfonic acid formalin condensate salt, the sulfonating agent generally includes sulfur trioxide, sulfuric anhydride, fuming sulfuric acid, Concentrated sulfuric acid, chlorosulfonic acid, etc. Among these, in the case of naphthalene, concentrated sulfuric acid is used, so that by-product dinaphthylsulfone and naphthalene disulfonic acid are produced less, and a large amount of high-purity naphthalenesulfonic acid can be obtained. Therefore, concentrated sulfuric acid is commonly used. However, concentrated sulfuric acid has low acidity and weak sulfonation ability, so when sulfonation is performed with equimolar sulfuric acid, the sulfuric acid concentration in the produced water becomes 60% by weight or less, and the reaction stops. Therefore, an excess of sulfuric acid of 1.25 moles or more relative to naphthalene is required. At the stage of neutralization after the condensation reaction with formaldehyde, this excess sulfuric acid is neutralized to form an alkali sulfate, generally sodium sulfate, in the solid content of the dispersant.
It will contain more than %. When this secondary sodium sulfate is made into an aqueous dispersant solution (usually about 40%), the temperature is 15°C.
At temperatures below, it crystallizes as a decahydrate, precipitating at the bottom of a tank or clogging pipes, making it impossible to handle it correctly as a solution. This sodium sulfate can be removed by cooling and filtering, but this requires enormous costs for cooling equipment and electricity, and reduces productivity. [0004] According to JP-A-60-106523, the crystallization temperature is lowered by forming a complex salt of sodium and potassium, but with the above amount of sulfate, precipitation occurs at temperatures below 5°C. [0005] Therefore, excess sulfuric acid is usually removed by neutralization using liming sodation. That is, in order to remove excess sulfuric acid, it is removed as calcium sulfate using calcium hydroxide or calcium carbonate. According to this method, the naphthalene sulfonic acid formalin condensate is also filtered and fractionated as a calcium salt, and then converted into a sodium salt by sodation with sodium carbonate, which is then filtered and fractionated from calcium carbonate.This process involves two filtration processes, which is extremely unproductive. The manufacturing method is commonly used. [Means for Solving the Problems] The production method of the present invention uses fuming sulfuric acid as a sulfonating agent, and it is possible to reduce the yield of naphthalene sulfonic acid depending on a specific reaction molar ratio to naphthalene. Furthermore, by forming a composite salt with a specific molar ratio of sodium and potassium, an aqueous dispersant solution that does not precipitate sulfate crystals even at 0°C can be obtained. This is what made it possible. That is, the present invention relates to a method for producing a cement dispersant characterized by the following (1) and (2) in the production of an alkali salt of a naphthalene sulfonic acid formalin condensate. ■; 1 mole of naphthalene to 1 mole of fuming sulfuric acid
．． Sulfonation with 12 to 1.17 mol (calculated as sulfuric acid). [0009] ■: The alkaline salt consists of a double salt of a sodium salt and a potassium salt, and neutralization is performed with 0.8 to 1.2 mol of the potassium salt per 1 mol of the sodium salt. [0010] For 1 mole of naphthalene in the present invention,
A sulfonated product in which the amount of fuming sulfuric acid is in the range of 1.12 to 1.17 moles provides a high yield of naphthalenesulfonic acid and a small amount of unreacted sulfuric acid. If the molar ratio of fuming sulfuric acid is lower than 1.12, an increase in unreacted naphthalene, an increase in the amount of unreacted sulfuric acid, an increase in by-product dinaphthylsulfone, etc. occur. Further, when the molar ratio of fuming sulfuric acid is higher than 1.17, the by-product naphthalenedisulfonic acid increases. [0013] The neutralizing salt requires a potassium salt in a range of 0.8 to 1.2 mol per 1 mol of the sodium salt.
There is no crystal precipitation of inorganic salt even at 0°C. When the amount of potassium salt is less than 0.8 mol or more than 1.2 mol per mol of sodium salt, the precipitation temperature of the inorganic salt increases. [0015] The fuming sulfuric acid used in the present invention is 20% to 6%
It is concentrated sulfuric acid that has absorbed 5% sulfur trioxide, and is not particularly limited. Examples of sodium compounds forming neutralized salts include sodium hydroxide and sodium carbonate, and examples of potassium compounds include potassium hydroxide and potassium carbonate. Sodium hydroxide and potassium hydroxide during neutralization can be added separately, or they can be mixed and added together. It is also possible to add sodium hydroxide and potassium hydroxide during final pH adjustment. The production method of the present invention, that is, reactions such as sulfonation and condensation with formaldehyde, are performed under known conditions.
Details will be explained in Examples below. The dispersant prepared by the production method of the present invention is used as a dispersant for concrete, mortar, cement paste, etc. [0020] Other cement additives (materials) such as high performance water reducing agents, fluidizing agents, AE agents (air entraining agents), AE water reducing agents, retarders, early strength agents, accelerators, foaming agents, foaming agents, etc. agent, antifoaming agent, water retention agent, thickener, waterproofing agent, rust preventive agent, coloring agent, antifungal agent, crack reducing agent, water-soluble polymer, swelling agent, fly ash, blast furnace slag, silica fume, etc. Combination use is also possible. [Examples] The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. EXAMPLE A typical manufacturing method of the present invention will be described. 1 mole of naphthalene was charged into a reaction vessel, and 1 mole of naphthalene was charged.
The temperature was raised to 20 °C, and while 1.15 mol of 25% oleum (sulfuric acid equivalent) was added dropwise, the temperature was raised to 160 °C.
A sulfonated product was obtained by aging at ℃ for 3 hours. After that, 9
The mixture was cooled to 0°C, 3 mol of water was added, and while 1.0 mol of 37% formalin was added dropwise at 90°C, the temperature was raised to 100°C and reacted for 25 hours. Water was then added to obtain a condensate. 4
Cool to 0℃ and add sodium hydroxide and potassium hydroxide.
Add an equimolar amount of 8% aqueous solution to adjust the pH to 9, and reduce the solid content to 4.
Adjusted to 0%. Table 1 shows the contents of the sulfonated products produced according to the above production method by varying the amount of oleum and the molar ratio of concentrated sulfuric acid.
Shown below. [Table 1] *1 Reaction rate to naphthalene (mol%) *2
(%) in the reaction system From the results in Table 1, the product of the present invention has a higher amount of naphthalene monosulfonic acid, which is an active ingredient after sulfonation, than the comparative product (87% or more), and a lower amount of unreacted sulfuric acid. Few (7%
(below) It can be seen that the reaction rate is even higher. Condensation was carried out according to the example, neutralization was carried out by changing the molar ratio of the alkali salt (pH=9.0), and the solid content was 40%.
Table 2 shows the determination of the presence or absence of crystal precipitation after storage at a low temperature of 0° C. for 30 days. [0028] As is clear from the results in Table 2, it can be seen that the complex alkali metal salts within the scope of the present invention do not cause precipitation due to crystal precipitation compared to the comparative products. Next, Table 3 shows the formulation of concrete, and Table 4 shows the dispersion performance (fluidity performance) of the dispersant of the present invention, which was produced according to the above-mentioned example, on concrete. [0031] Materials used/cement: Ordinary boltland cement Specific gravity = 3.
16.Sand: Kinokawa river sand
Specific gravity = 2.56 - Gravel: Crushed stone from Takarazuka
Specific gravity = 2.
60 Concrete mix 0032 [Table 3] 0033 W: Water a: Sand +
Gravel (S+G) C: Cement
S: sand G: gravel 0034 [Table 4] 0035 *1 Dispersant manufactured according to the typical manufacturing method of Examples (average molecular weight = 9000) *2 J
IS A 1101 “Method for measuring the fluidity of concrete”
Measured according to. As is clear from the results in Table 4, it can be seen that the dispersant of the present invention exhibits excellent effects as a dispersant for concrete. [0037] The method for producing a cement dispersant of the present invention allows for a significant simplification of the production process, resulting in great cost benefits. Further, since the cement dispersant according to the present invention has excellent dispersion performance, it can be used in a wide range of applications including ready-mixed concrete and secondary product fields.

Claims (1)

[Claims] 1. A method for producing a cement dispersant, characterized in the following (1) and (2), in the production of an alkali metal salt of a naphthalene sulfonic acid formalin condensate. ■: oleum 1.12 to 1.1% per mole of naphthalene.
Sulfonation with 17 mol (calculated as sulfuric acid). ■; The alkaline salt consists of a double salt of sodium salt and potassium salt, and potassium salt is 0.8 per mol of sodium salt.
Neutralization with ~1.2 mol.