JPS58115022A - Preparation of calcium carbonate - Google Patents

Abstract

PURPOSE:To make it possible to prepare spindle type calcium carbonate with slight aggregation property in forming and drying, by adding water glass or silica sol to a suspension f calcium hydroxide, and blowing gaseous carbon dioxide into the suspension. CONSTITUTION:Water glass or silica sol in an amount of 1-10pts.wt. expressed in terms of SiO2 based on 100pts.wt. solid Ca(OH)2 is added to a suspension of the Ca(OH)2 in 5-20wt% concentration at 20-50 deg.C, and gaseous carbon dioxide is then introduced into the suspension at >=150l/min/kg Ca(OH)2 flow rate under 1-10kg/cm<2> (gauge pressure). Thus, the spindle type calcium carbonate having 0.05-0.2mum minor axis and 0.5-1.0mum major axis is obtained. The surface of the spindle type calcium carbonate particles is further treated with an organic modifying agent, e.g. an alkali metallic salt of a fatty acid or resin acid, or an inorganic modifying agent, e.g. hydrogen fluoride, sulfurous acid gas (sulfur dioxide), titanium or aluminum. According to the method, the calcium carbonate having improved characteristics as a filler for coated paper or aqueous coating materials is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing calcium carbonate, and more specifically, the short axis is 105 to a2 pm.

Spindle-shaped calcium carbonate 0II with major axis a5~1.0 pm
This relates to an I-making method. More particularly, the present invention provides concentration 5
~20 parts by weight (- means parts by weight unless otherwise specified), calcium hydroxide suspension at a temperature of 20 to 50°C, and 100 parts by weight of calcium hydroxide solids (all parts below mean parts by weight). water glass or silica sol to 810! Add 1 to 10 parts in terms of conversion, and add a concentration of 15 to 5
By introducing carbon dioxide gas of 5 volumes to 1 to 10 under a pressure of 4 I/愼2 (gauge pressure) at a flow rate of 150 J/min/noodle oa (on) or more], the short axis (105 to a2pm
The present invention relates to a method for producing spindle-shaped calcium carbonate with a long iα of 5 to 1,0 μm and a very good dispersibility, and to a method for producing calcium carbonate in which the surface of calcium particles is treated with an organic or inorganic modifier.

Precipitated calcium carbonate OI! As for the II production method, known methods include a carbonation method in which milk of lime is reacted with carbon dioxide gas, and a carbonate solution method in which calcium chloride and a water-soluble carbonate are reacted in a solution state. Currently, in the industrial carbonation method, fine cubic calcium carbonate with an average particle diameter of less than 1 μm and a major diameter of t are used.

Spindle-shaped X-ray needle-shaped O calcium carbonate has been produced and is widely used in paper, rubber, plastic, paint, ink and other industries.

When using calcium carbonate as an additive for coated paper,
Fine particles that are not surface-treated and do not aggregate are considered suitable for gloss, opacity, visibility, and printability. In addition, in the plastic coating industry, the surface of calcium carbonate is made to have a higher dispersibility (organic substance or inorganic substance + modification treatment to improve dispersibility) and compatibility with its matrix or vehicle. Improved minimum particle size In order to meet these demands, the particle size [L05
~α-5pm surface modified cubic calcium carbonate is currently mainly used.

On the other hand, if the major axis of spindle-shaped particles is less than 1 μm,
There are also characteristics that are not found in fine cubic particles, and various studies have been conducted on their production methods, but there is a method to produce them stably and uniformly (K11).In particular, regarding the agglomeration mechanism, it is said that moldy cubic particles agglomerate during drying. On the other hand, spindle-shaped particles are dominated by irregular agglomeration during the production of calcium carbonate, and from an industrial point of view they have more difficulties than the production of cubic particles.

The present invention solves these difficulties all at once, and facilitates the mass production of spindle-shaped particles with low cohesiveness during generation and drying, which is good and has good reinforcing properties including flow properties as an additive for paper, rubber, plastics, and paints. The present invention provides a method for producing calcium carbonate having extremely useful properties in terms of other applied physical properties, and a method for producing a product modified on the 7OII surface.

The present invention will be explained in more detail. “Conventionally, the conditions for producing spindle-shaped calcium carbonate with a short axis of α2 to a5 μm and a long axis of 1 to 471 m are contrary to the conditions for producing fine cubic calcium carbonate of 17 m or less. As described above, the carbonation reaction was carried out using carbon dioxide at a temperature of 20℃ or higher under normal pressure at a flow rate of 50J/min/40A (Of mushrooms or less), and in detail, crystals were formed in one direction. 1-6X focuses on selecting conditions that will increase growth as much as possible.

We found that the concentration and temperature of milk of lime are in the range of 8-20°C and 20-50°C, which are the conditions for producing large spindle-shaped particles.
For the carbonate bus, we selected a combined condition of 150t/min/1kca (olx or higher, which is the basic condition for producing fine cubic particles), and added 1 to 10 parts of water glass or silica sol to 100 parts of calcium hydroxide. [By introducing a carbon dioxide gas tank under pressure of 1 to 10%/lar" (gauge pressure) to a calcium hydroxide suspension obtained by
The present invention was completed by discovering that it is possible to produce fine, spindle-shaped calcium carbonate having a length of L2pm and a long axis of α5 to t'oμm with very good dispersibility.

That is, the present invention has a concentration of 5 to 20% by weight and a temperature of 20 to 50%.
Water glass or silica sol in an amount of 1 to 10 parts (calculated as 8102) per 100 parts by weight of solid calcium hydroxide is added to a calcium hydroxide suspension at
150j/min/KgOa (under pressure of 1" (gauge pressure)
OB) By introducing carbon dioxide gas at a flow rate of 1 or more, the short axis [LO
5~1L2F! El, a method for producing calcium carbonate characterized by obtaining spindle-shaped calcium carbonate with a major axis ['L of 5 to 10 μm, a concentration of 5 to 20% by weight, a temperature of 20
Calcium hydroxide @ local solution at ~50°C, 810 parts per 100 parts by weight of calcium hydroxide solid content! Add water glass or silica sol in an amount of 1 to 10 parts in terms of 1 to 101 parts.
15[1j/min/K under pressure of 14/♂ (gauge pressure)
Carbon dioxide gas is introduced at a flow rate of yCa(OH)1 or more to produce spindle-shaped calcium carbonate with a short axis of 105 to α2 pm and a long axis of 15 to 1.0 μm + Q, and the surface of the calcium carbonate particles thus obtained is subjected to organic or inorganic modification. The present invention provides a method for producing calcium carbonate, which is characterized in that it is treated with a chemical agent.

At this time, if the concentration of milk of lime is less than 5 - and the temperature is less than 20 °C, even if other conditions are within the specified range of the present invention [11 μ
If fine calcium carbonate of less than m is produced, the lime milk concentration is 20°C, and the temperature exceeds 50°C, aggregates of spindle-shaped particles will be obtained, and the desired easily dispersible calcium carbonate particles will not be obtained. . Also, the amount of water glass or silica sol added is 5108 parts per 100 parts of calcium hydroxide solid content.
If the conversion is less than 1 part, the major axis exceeds 1.0 μmf, and 10
If the pH exceeds 100%, the major axis becomes less than 0.5pH, which may cause problems with polydispersity, probably because the growth of the particles is suppressed too much. Note that the pressure of carbon dioxide gas during the reaction is one of the most important conditions related to the present invention, but if it is less than 1 to 4/18 (gauge pressure), the major axis is 1.0 pm and the minor axis is rL2pwrt@, 1
0 K4/lx" (gauge pressure) [If it exceeds, a mixture of fine cubic particles and spindle-shaped particles will be obtained." , alkylarylsulfonic acid or its alkali metal salt, anionic surfactant such as higher alcohol sulfate, alkali metal salt of polyacrylic acid that imparts hydrophilicity, maleic acid and imbutylene, styrene or vinyl acetate, etc. and O copolymer. The inorganic modifiers are hydrogen fluoride, sulfur dioxide gas, phosphoric anhydride, titanium, aluminum,
These include gold ygo chloride or fluoride such as zinc and silicon.

As described above, by carrying out the carbonation reaction within the above-mentioned condition ranges of the present invention, the desired minor axis α05 to 1 can be achieved for the first time.
It is possible to produce spindle-shaped calcium carbonate with a length of 2 μm2 and a length of a5 to 1.0 pm and very good dispersibility.

The products produced by the method of the present invention are extremely useful as additives for coated paper or water-based paints, and those further ibmized with organic or inorganic acids can be used as fillers for rubber, plastics, and paints due to their easily dispersible properties. Because of its excellent affinity with the above, it can exhibit high reinforcing properties, gloss, etc.

The present invention will be explained in more detail below using Examples.

Example 1 10 - Calcium hydroxide suspension at 50°C in concentration 7.50
04, No. 5 water glass in 8103 minutes '57.5-
After addition and stirring, add 25 volumes of carbon dioxide gas at 30℃ for 3-15 minutes.
．． ” (gauge pressure) under pressure 170j/min/40a
(OH) * is introduced to perform a carbonation reaction, and after dehydration with a centrifuge, drying, crushing, and classifying, the short axis rL1
One ton of spindle-shaped calcium carbonate having a length of 0 μm5 and a major axis of α7 μm was obtained.

Example 2.3 and Comparative Examples 1 to 4 In the same manner as in Example 1, the conditions were changed as shown in Table 1 to obtain calcium carbonate having different particle sizes.

The results are shown in Table 1.

Application Example 1 Table 2 shows the particle size analysis values of 2 strokes or less measured with a 1 micron photosizer manufactured by Seishin Enterprises and the coated paper application data of Examples 1 to 5 and Comparative Examples 1 to 4.

Formula for coated paper: Calcium carbonate aqueous dispersion 100 parts (as solid content) Oxidized starch (Eclipse M8JI4600) 5 parts Latex (Sumitomo No Katatsuku 12 parts 81!507), Coating color of the above composition was applied to commercially available high-quality paper. Apply by hand using a coating bar, dry at room temperature, then season.
The test was conducted at a coating weight of 5f/inertia.

The trial method is as follows: Glossiness: J113 P8142. .

Whiteness: J Engineering 8P812! i1, good opacity; JI8 P 8138 Engineering G? Big; Calcium carbonate 1% of Table 42 Example 4 Actual Oval Example 1! Shoulder fluid was adjusted to a t-15 concentration, and 20 parts of fatty acid sodium at a concentration of 10% i was added to 100 parts of calcium carbonate solid content at 90°C while introducing carbon dioxide gas, 15 minutes 113
Continue stirring the carbon dioxide gas. Dehydrate and dry the served product.
Surface-modified calcium carbonate was obtained by crushing and classifying.

Application example 2 Example 1.4 and commercially available light calcium carbonate (minor axis α
After premixing 50 parts of spindle-shaped particles (Sμ, long diameter 2.5 μmc) and 100 parts of polypropylene resin (trade name 1 Noprene W1.01J, manufactured by Sumitomo Chemical Industries),
After mixing the rolls for a few minutes, take out the sheets, pelletize them with a pelletizer, and put them into an injection molding machine at 230°C to prepare Mu8TM standard test pieces. t was measured.

Whiteness; JI8 P8123 (45°-09
) Surface gloss; Mu8TM D525 (60°-60°
) Tensile strength: Mu8TM D6SB Tensile strength: Mu8τM D79G The test results are shown in Table 5.

Table 5 From the results in Table 5, those treated with a modifier (implemented $14
) gives the polypropylene resin significantly superior physical properties compared to those without treatment (Example 1 and comparative commercial products).

As explained in detail above, the spindle-shaped calcium carbonate produced by the method of the present invention does not have the drawbacks of the conventional cubic and spindle-shaped calcium carbonate, and has the advantages of both, and can be used in paper, rubber, etc. Extremely excellent fillers for plastics and paints (3 people)

Claims (1)

[Claims] 1) Concentrated IjL 5-20 weight cake, warm wrinkles Calcium hydroxide suspension at 20-50°C, calcium hydroxide solid content 100
Water glass or silica sol is added in an amount of 1 to 10 parts by weight based on 8101, and 1 to 10 K4/t.
150j/min/lie under pressure of s” (gauge pressure)
By introducing carbon dioxide gas at a flow rate of 0a (OH) or more, the short axis [
LO5-124m, long axis a5-LOpm (calcium carbonate 0 @ method characterized by converting to D spindle-shaped calcium carbonate. 2) #ff15-2o weight 1, temperature 1L 20-50℃ calcium hydroxide suspension , calcium hydroxide solid content 1
00 parts by weight of water glass or silica sol in an amount of 1 to 10 parts per day calculated to 1 to 10 Kg/cm"
150 j1 min/1110a under pressure (gauge pressure)
(OH) Introducing carbon dioxide gas at a flow rate higher than Takao and short axis a05
~a2Pm% Major axis α5~t, Opmo spindle-shaped calcium carbonate is produced, and the surface of the thus obtained calcium carbonate particles is treated with an organic or inorganic modifier.