JPS5826031A - Manufacture of calcium carbonate with high dispersibility - Google Patents

Abstract

PURPOSE:To obtain calcium carbonate having a superior affinity for a vehicle and an aqueous medium and superior dispersibility in them by adding a specified org. carboxylic acid compound or a specified org. phosphonic acid compound to an aqueous medium or a reactive liq. CONSTITUTION:To a reactive liq. such as milk of lime is added at least 1 kind of compound selected from org. carboxylic acid compounds and org. phosphonic acid compounds expressed by formulaeI, II. Gaseous CO2 in then blown into the reactive liq. contg. the additive to prepare a slurry of calcium carbonate. Thus, calcium carbonate having a superior affinity for a vehicle and an aqueous medium and superior dispersibility in them is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing light calcium carbonate (also referred to as precipitated calcium carbonate). The present invention provides light calcium carbonate which has excellent dispersibility and does not undergo solid-liquid separation even at high concentrations.

The method for producing light calcium carbonate includes carbonation method 1.
The lime-soda method and the soda method are known, and they are usually produced in a single-batch or continuous manner using the carbonation method or its modification method.

Light calcium carbonate is used in an extremely wide variety of ways1.
For example, it is used in rubber, plastics, paint, ink, pigments, paper manufacturing, fertilizers, toothpaste, medicine, organic synthesis, raw materials for cosmetics, fillers, etc. Manufacturing conditions are controlled to suit these uses, and products of various shapes such as cubic, spindle, columnar, or needle-like are manufactured according to the purpose of use. In addition, activated light calcium carbonate obtained by treating klIw with an outer case activator such as an aliphatic compound or an aromatic compound is also known.

For light calcium carbonate, FM the crystals after one reaction synthesis! J Dry powder products and slurry products prepared without drying are used industrially. Powder crystals are used as fillers kneaded or compounded in the rubber, plastic, and pharmaceutical industries, and also in inks.

It is consumed in large quantities as a filler in aqueous linoleum or 0/Wll (oil in water ml) emulsions in paint products, and as a filler in paste products in the cosmetics and toothpaste industries. Slurry products are also useful in the pulp and paper industry for producing coated paper.

What is important for quality enhancement in these wide range of applications is to show uniform dispersibility.1 For example, in emulsions and slurries, long-term changes in quality such as mW and separation will not occur over time. When it comes to slurry products with a concentration of 0%, it is easy to obtain a slurry with a high concentration as much as possible from the economical point of view of transportation, and it is extremely important that solid-liquid separation is less likely to occur.

In conventional manufacturing methods, dispersibility in emulsions and pastes was poor, and a large amount of emulsifier had to be added.

For slurry products, although there are some differences depending on the size and shape of the crystals, the maximum solid content concentration is about 55 to 40% by weight in order to maintain relatively stability without causing solid-liquid separation. Then, solid-liquid separation occurs during transportation, resulting in poor fluidity and difficulty in handling.

The present inventors have solved the above problems with dispersibility.

The present invention was developed through extensive research into light calcium carbonate, which has excellent stability.

That is, 1. When producing light calcium carbonate, the present invention includes the following H), (B), &
Adding at least one type of organic carboxylic acid compound or organic phosphonic acid compound represented by the general formulas -1 and 2) is I! #Relating to a method for producing light calcium carbonate that has good dispersibility as mold.

)? ■ (MO) * P1 package P- (OM) Yukirei's IJ4 Nitsusha, Hereinafter, the carbon dioxide gasification method, which is the most typical manufacturing method for quality II calcium carbonate, will be explained as an example.

Representative examples of the compounds represented by the above general formula are as follows.

That is, as shown by the general formula (a), the following I
s) 2-phosphonobutane-1,2゜-tricarboxylic acid or its salt represented by the formula (b), and maleic anhydride-acrylic acid represented by the following formula (2). Acid co-heavy metal hydrolyzate or its salt, or poly(meth)acrylic acid or its salt,
Examples include a hydrolyzed maleic anhydride-vinyl acetate copolymer or a salt thereof, a maleic anhydride-oxycarboxylic acid condensate or a salt thereof, and the like. In addition, those represented by the general formula 〇/U include aminotrimethylenephosphonic acid or its salt represented by the following formula (2), and engineered diamine tetramethylene phosphonic acid or its salt represented by the following formula (4). . Furthermore, as shown in the general formula),
1 to human 1 xyethylidene-1 represented by the following formula (51)
, 1-diphosphonic acid or a salt thereof.

CH2C00H (m + n = 6 to 10) (2) These are usually used as an aqueous solution, and two or more types may be heated and used.

In the present invention, the amount of the above-mentioned compound (hereinafter sometimes referred to as an additive) added is 0.000% per reaction solution. It suffices if it is present at a concentration of 1 ppm or more; if it is less than that, the desired effect of the present invention cannot be fully achieved. Usually 1 = 3
A concentration range of 0 ppm is preferred. Generally, the effect increases as the amount added increases, but the amount may be appropriately determined by taking into account the cost and effect of addition. The present invention is.

It can be applied not only to the batch method but also to the continuous carbonation method, and a sufficient effect can be obtained by controlling the concentration of the additive in the reaction solution so that it falls within the above concentration range. There is no difference at all from the batch type.

When carrying out the present invention, the temperature of the reaction solution may be set at any temperature, but it is preferably kept within the range of 20 to 90°C. This is because the reaction rate slows down below 20°C, and the effect of the additive diminishes above 90°C.

The present invention can be applied to methods for producing light calcium carbonate other than the carbonation method, and a predetermined amount of the above (a) to (a)
A sufficient effect can be achieved by adding at least one of the additives represented by → to the reaction solution in advance or during the reaction.

According to the method of the present invention, the calcium carbonate obtained can be freely controlled from fine crystals of about 0.05 μm, which could not be obtained by conventional methods, to relatively large crystals of about 3 to 5 μm. The light calcium carbonate obtained by the method of the present invention has extremely excellent dispersibility in vehicles and aqueous media, and can be processed into emulsions and pastes that are uniform and have good dispersion stability. In particular, the slurry concentration was limited to 35 to 40% by conventional methods, but the slurry obtained by the method of the present invention does not cause solid-liquid separation and has good fluidity even at 55 to 60%. Arashi is a good thing. I
! It is difficult to transport it as a slurry crystal.

Since it is possible to increase the slurry concentration, there are significant economic benefits in terms of transportation costs and workability.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 In the light calcium carbonate production plant 111c shown in Figure 1, the lime milk concentration in one reaction solution was set to 20% by weight, and to this was added 11 m of 17% water of a hydrolyzate of polymaleic anhydride! (referred to as additive (1)), 2T phosphonobutane-1,2,4
-) 17% aqueous solution 1m of recarboxylic acid (referred to as additive), 60% of ethylenediaminetetramethylenephosphonic acid
% aqueous solution (referred to as In+ agent o+) and a 58% aqueous solution of 1-hydroxyethylidene-1,1-diphosphonic acid (referred to as additive +41), and while stirring, carbon dioxide gas was blown into the mixture to obtain a 27% aqueous solution of 27% by weight. A slurry of calcium carbonate was obtained.

This slurry liquid 200 mm was taken into a measuring cylinder with a capacity of 200 mm, and was left at room temperature for 24 hours to observe the state of solid-liquid separation. The height of the boundary line of solid-liquid separation was measured and summarized in Table 1. This shows that the sample has excellent monodispersity with a high height (am).

For comparison, measurements were also made with no additives added, and the results are shown in the same Table 1.

Table 1 (Note) Height when completely uniformly dispersed = 193 (scale 2
01)sj) Example 2 The 27% by weight slurry obtained in Example 1 was filtered, and the obtained crystals were air-dried. Using this air-dried product, a homogeneous slurry of 60% by weight (high speed stirrer 7,000 vpm #
15 minutes) was prepared, and its dispersibility was observed in the same manner as in Example 1, and the results are summarized in Table 2.

For comparison, additive-free products are also shown in Table 2.

Table 2 (Note) Height when completely uniformly dispersed: 19cIK (scale 200m) Example 3 From the 60% by weight slurry prepared in Example 2,
Coating agents for brittle paper were prepared using four types of coating agents, one containing additives and one without additives for comparison. The formulations and formulation ratios are as shown below, and after uniformly dispersing them using a high-speed stirrer (4°00 Orpm, 10 minutes), the emulsion stability of the coating agent was examined. The measurement method was to observe the state of solid-liquid separation, and was the same as the method shown in Example 1, but the standing period was 3 days. The results are summarized in the IK3 table.

Preparation agent and proportion Table 3

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an overview of the carbon dioxide compounding method. ■-Limestone　　　　1; Crushed Seal: Coke 2: Burnt ■: Carbon dioxide gas 32 water sum ■: Quicklime 4: Reaction V: Milk of lime 5: Filtration v: 4I quality calcium carbonate 6: Drying 7: Grinding

Claims (1)

[Claims] When producing light calcium carbonate, at least one organic carbonaceous compound or organic phosphonic acid compound represented by the following general formula is added to the aqueous medium or reaction solution. Method for producing dispersible light calcium carbonate characterized by