JPH06127994A - Dispersing agent for gypsum-water slurry - Google Patents

Abstract

PURPOSE:To improve foam stability by mixing a naphthalenesulfonic acid- formaldehyde condensation product with a formaldehyde condensation product of a compound expressed by specific formulas. CONSTITUTION:The dispersing agent for gypsum-water slurry is obtained by mixing the naphthalenesulfonic acid-formaldehyde condensation product (A) with the formaldehyde condensation product (B) and/or (C) of the compound having 1000-50000 molecular weight and expressed by the formula I and/or II in a weight ratio, (A)/((B)+(C))=(50-95)/(50-5) or (A)/((B) or (C))=(50/95)/(50-5). Next, 0.1wt.% dispersing agent aq. solution expressed in terms of solid matter per gypsum is added into the gypsum-water slurry made by mixing hemihydrate gypsum with water to obtain the gypsum-water slurry high in foam stability expressed by 7 formula III.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a dispersant for gypsum-water slurries. More specifically, plaster during gypsum board manufacturing-
The present invention relates to a dispersant having excellent dispersibility of water slurry and foam stability.

[0002]

2. Description of the Related Art Conventionally, a naphthalenesulfonic acid formaldehyde condensate (hereinafter referred to as a naphthalene type) having a high dispersibility has been known as a dispersant for gypsum-water slurry. In the production of gypsum board, by using a naphthalene-based dispersant, the amount of kneading water is reduced, the drying time can be shortened, and the productivity is improved. The production of gypsum board, according to a predetermined composition, plaster, an admixture aqueous solution, a curing accelerator aqueous solution and the like are simultaneously charged into a kneading machine called a pin mixer and discharged with stirring for about 10 seconds, It consists of a production process that is sandwiched between upper and lower boards (paper).

[0003]

However, even if a predetermined amount of foam is thrown in, since its foam breaking property is large, about twice the amount of foam is usually thrown in anticipation of the volume to be broken. is the current situation. Further, coarse bubbles generated in the process of breaking the bubbles aggregate at the interface with the board, which hinders the adhesion with the gypsum slurry, causing poor quality.

[0004]

[Means for Solving the Problems] In view of the above problems, the present inventors have made earnest studies, and as a result, found that the dispersant had a great influence on the breaking of foam, and as a result of further investigation based on this finding, The present invention has been completed.

That is, the present invention is represented by (1) a formaldehyde condensate of naphthalene sulfonic acid and (2) a formaldehyde condensate of a compound represented by the following general formula (a) and / or represented by the following general formula (b): Disclosed is a gypsum-water slurry dispersant comprising a compound formaldehyde condensate.

[0006]

[Chemical 2]

The naphthalenesulfonic acid formaldehyde condensate used in the present invention is a known naphthalene-based dispersant, and examples thereof include Mighty G-150 (manufactured by Kao Corporation) and Sunflow-PS (manufactured by Sanyo Kokusaku Pulp Co., Ltd.). The product name such as) can be used and is not particularly limited.

R in the general formulas (a) and (b) is
H 2 or a linear or branched alkyl group having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, pentyl and hexyl. Further, X in the formula is an alkali metal and is not particularly limited, but sodium and potassium are preferable.

The condensate of the compound represented by the general formula (a) or the general formula (b) and formaldehyde can be obtained by a commonly used known synthetic means, for example, after sulfonation of alkylphenol or alkylnaphthol with concentrated sulfuric acid. , Which is obtained by any method such as a condensation reaction with formalin (30-40% by weight formaldehyde aqueous solution) to form an alkali metal salt, or a method of preliminarily condensing an alkylphenol or the like as a sulfite with formalin You can The average molecular weight of the condensate of the compound represented by the general formula (a) or the general formula (b) and formaldehyde is respectively
The range of 1000 to 50000 is preferable, and the range of 2000 to 13000 is more preferable.

In the dispersant of the present invention, (1) a naphthalenesulfonic acid formaldehyde condensate (a) and (2) a formaldehyde condensate of a compound represented by the following general formula (a) (b) and / or the following general formula The weight ratio of the formaldehyde condensate (c) of the compound represented by the formula (b) is a / (b +
C) = 50-95 / 50-5, or a / (b or c) = 50-
The range of 95/50 to 5 is preferable.

The gypsum-water slurry dispersant of the present invention can be used in combination with a known dispersant other than naphthalene-based dispersants, such as lignin-based, melamine-based and carboxylic acid-based dispersants.

[0012]

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

(1) Production Example of Metacresol Sulfonic Acid Formalin Condensate Sodium Salt In a stirred reaction vessel, sodium metacresol sulfonate is added.
Charge 1.0 mol, and add 0.1N sodium hydroxide aqueous solution to adjust the pH to 11 and the solid content concentration to 35% by weight. Next, the adjusted solution is heated to 85 ° C., 3.0 mol of formalin (37% aqueous formaldehyde solution) (as formaldehyde) is added with stirring, and the reaction mixture is stirred under reflux for 10 hours. After cooling, add water to add a solid content of 25
% To obtain a condensate of the present invention having a weight average molecular weight of 1500 (F-1). Here, the weight average molecular weight is a value measured by a gel permeation chromatography method (based on sodium polystyrene sulfonate). Then, the reaction time under reflux was changed by the same production method to obtain a condensate having a weight average molecular weight of 7700 to 48000 (F-2 to
F-4) was produced.

(2) Production Example of Sodium Salt of Methylnaphtholsulfonic Acid Formalin Condensate Sodium methylnaphtholsulfonic acid sodium salt in a stirring reaction vessel
Charge 1.0 mol, add 5 mol of water and raise the temperature to 90 ° C.
Add 0.9 mol (as formaldehyde) of formalin (37% formaldehyde in water). Thereafter, the mixture is stirred at 102 ° C. under reflux for 8 hours. After cooling, 40% aqueous sodium hydroxide solution was added to adjust the pH to 10, and water was added to adjust the solid concentration to 25% by weight, and the weight average molecular weight was 1800.
To obtain the condensate of the present invention (M-1). In the following, the reaction time under reflux was changed by the same production method so that the weight average molecular weight was 95%.
00-46000 condensates (M-2 to M-4) were produced.

(3) Evaluation of fluidity of gypsum-water slurry and stability of foam The test materials shown below were charged into a small pin mixer, and
After mixing for seconds, the fluidity of the slurry and the stability of the foam were evaluated. The results are shown in Table 1. Test material Hemihydrate gypsum; 1000 g water; 600 g admixture; 0.1% by weight (in terms of solid content) of gypsum of the mixture of the dispersant and the above condensate in the proportions shown in Table 1 is added as an aqueous solution. Foam: A 1% aqueous solution of Emal D-3-D (manufactured by Kao Corporation) was used to produce 0.05 g / ml (20 times) foam with a foaming machine.
Add ml (400 ml). -Measurement of fluidity: A cylindrical cone having an inner diameter of 50 mm and a height of 50 mm was filled with the slurry, and the spread (mm) after extraction was measured. -Foam stability: Foam stability (%) was determined from the specific gravity of each material by measuring the weight of the gypsum-water slurry per constant volume by the following formula.

[0016]

[Equation 1]

[0017]

[Table 1]

Note) The symbols of the dispersants in Table 1 mean the following. N: Naphthalene-based Mighty G-150 (manufactured by Kao Corporation) S: Naphthalene-based Sunflow PS (Sanyo Kokusaku Pulp)
F-1; Metacresolsulfonic acid formalin condensate sodium salt, weight average molecular weight 1500 F-2; Metacresol sulfonic acid formalin condensate sodium salt, weight average molecular weight 7700 F-3; Metacresol sulfonic acid formalin Condensate sodium salt, weight average molecular weight 18000 F-4; metacresol sulfonic acid formalin condensate sodium salt, weight average molecular weight 48800 M-1, methylnaphthol sulfonic acid formalin condensate sodium salt, weight average molecular weight 1800 M-2; methyl Naphtholsulfonic acid formalin condensate sodium salt, weight average molecular weight 9500 M-3; Methylnaphtholsulfonic acid formalin condensate sodium salt, weight average molecular weight 15000 M-4; Methylnaphtholsulfonic acid formalin condensate sodium salt, weight average molecular weight 46000

[0019]

The gypsum-dispersant for water slurry of the present invention is
It exhibits an excellent effect on foam stability in gypsum-water slurry. Therefore, improvement in the adhesiveness between the paper (board) and the slurry is expected. Also, since the fluidity of the slurry is improved,
The water reduction effect can improve productivity.

Claims (1)

[Claims] 1. A (1) formaldehyde condensate of naphthalene sulfonic acid, and (2) a formaldehyde condensate of a compound represented by the following general formula (a) and / or a formaldehyde of a compound represented by the following general formula (b). A dispersant for gypsum-water slurry, which comprises a condensate. [Chemical 1]