JPH0251419A - Calcium carbonate having high hiding property - Google Patents

Abstract

PURPOSE:To allow CaCO3 to exhibit high hiding property and to make the CaCO3 useful as a low-cost white pigment by using an inorg. white pigment as nuclei. CONSTITUTION:CaCO3 is formed with an inorg. white pigment such as TiO2, PbTiO3, ZnO, ZnS, lithopone or white lead as nuclei to obtain calcium carbonate having 5-95% CaCO3 content and high hiding property. This calcium carbonate is produced by adding an aq. calcium chloride soln. and an aq. ammonia soln. to an aq. suspension of the white pigment and introducing CO2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to highly invisible calcium carbonate, and more particularly, it relates to an inorganic white pigment, such as an oxidized Titanium,
Alternatively, a method using zinc oxide as a core and a reaction production method of calcium carbonate in a suspension thereof using a liquid phase method or a combination of a liquid phase method and a gas method, in which the calcium carbonate content is 5 to 95% by weight. (all % below), preferably 50 to 95% of high hidden calcium carbonate.

Compared to titanium oxide, zinc oxide, etc., which are used as inorganic white pigments, calcium carbonate, which is manufactured by currently known manufacturing methods, has essentially inferior hiding properties, and is used as an extender pigment used for diluting pigments. In other words, it could not escape from the realm of being a filler. Related industries that use inorganic white pigments have strongly requested the development of an inexpensive white pigment to replace inorganic white pigments such as titanium oxide and zinc oxide, which are scarce and expensive in terms of resources.

In the products of the present invention, the original shape of inorganic white pigment particles such as titanium oxide and zinc oxide as the core is maintained, and even in products containing 80% IXM calcium, they are almost indistinguishable by electron microscopy, and calcium carbonate crystals form a thin film from the surface of the prokaryotic particles. Coupled with the fact that the calcium carbonate has a low pay-hiding property, a product that directly expresses the pay-covering function of the core particles is obtained, creating a completely new calcium carbonate that exceeds the pay-covering function of conventional calcium carbonate. It could have been done.

(Prior Art) Currently, various types of calcium carbonate are commercially available by selecting particle sizes based on cubic, spindle-shaped, or needle-shaped particles. Among them, from an optical standpoint, particles of approximately 1 in the range of visible light, which has recently been considered to be the particle size that improves the concealment properties of calcium carbonate alone, have the highest concealment properties among particle sizes.
Cubic calcium carbonate with a side of approximately 0.2p and tn, which corresponds to a wavelength of /2, is desired. However, calcium carbonate has a refractive index of 1.5 to 1.5, which has the greatest effect on concealment properties.
1.7 and 2.5 to 2.7 of titanium oxide. 2. Zinc oxide
0 is essentially inferior. Therefore, calcium IK oxide is generally not treated as a white pigment and is relegated to the range of extender pigment or filler, and the product of the present invention is basically of all <R quality both in terms of the idea and the product itself.

(Means for solving the problem) Known methods for producing calcium carbonate include a method of introducing carbon dioxide into a calcium hydroxide suspension or a calcium hydroxide suspension in carbon dioxide gas, and a method of introducing and reacting a calcium hydroxide suspension into a calcium hydroxide suspension, and By heating and stirring the calcium carbonate suspension, the calcium carbonate particles are aged and grown to increase the particle size! i! There is a manufacturing method. In either method, the substance produced is calcium carbonate itself.The inventors determined that it was impossible to improve the concealment function due to the woody defects of I&M calcium, and maintained the high concealment function. Inorganic white pigments such as titanium oxide and zinc oxide are used as the core, and instead of using the solid phase of calcium hydroxide as the raw material in the conventional manufacturing method, we focus on reaction in the liquid phase such as calcium chloride, and add ammonia and carbon dioxide gas to this. By the method of introduction, calcium carbonate crystals are uniformly formed on the surface of the core particle, which cannot be obtained by conventional solid-phase reactions, and the concealing function, which is a characteristic of the core particle, is hardly impaired, and the composition is It was discovered that by changing the calcium carbonate content from 5 to 9,596, particles exhibiting the exact functions of prokaryotic particles can be obtained.

The details of the product of the present invention are as follows: l) Inorganic white pigment as the core and refractive index Titanium oxide Refraction
Rate 2.5-2.7■ Titanic acid
Lead refractive index 2.7■ Zinc oxide refractive index 2.0■
Zinc sulfide refractive index
2.37■ Ritobon refractive index 1. 8-2.3(
ΦLead White Refractive index 1.84-2.09 In addition to the above, calcium titanate, barium titanate, etc. can be cited as inorganic white pigments. *The refractive index is based on the Mugeki Kagaku Handbook published by Bin Gihodo.

2) Method for producing highly concentrated calcium carbonate Add 5 to 45% of calcium chloride or calcium sulfate, which is a soluble calcium salt, at 10 to 50°C to the aqueous suspension of the white pigment as the core described above to obtain a molar amount. 5-28% of the volume, 5-35% (by volume) immediately after stirring the ammonia water at 10-50℃.
, carbon dioxide gas at 10-50℃ converted to calcium hydroxide, 1
By introducing the calcium at a rate of 1 to 30 plates per minute per gram, it is possible to obtain high-grade charcoal calcium. At this time, if the above-mentioned condition range is exceeded, film-like calcium carbonate does not precipitate and form on the surface of the core particles, and becomes only a mixture of the core particles and calcium carbonate, which can be a highly hidden calcium carbonate.

Furthermore, when the calcium carbonate content in the high-paying calcium carbonate is 5 to 95%, the product exhibits a high-hidden payload function that is a characteristic of the core particle, but the calcium carbonate content is 50 to 95%. A more preferable range is 95%.

In addition, if the desired calcium carbonate is difficult to precipitate on the surface in one treatment due to the composition of the raw material core, first pre-treat with a substance whose main component is silica, aluminum, etc. that has good affinity with calcium carbonate. In addition, a vehicle containing high-grade calcium carbonate can also be produced by the method of the present invention.

(Structure of the invention) The main points of the configuration of the present invention are listed as follows.

l) A natural or synthetic inorganic white pigment with high hiding power is used as a core.

2) Nuclear particles! ! ! By reacting a soluble calcium salt with soluble hydroxide and carbon dioxide in an IQ liquid, a film of calcium carbonate is precipitated on the surface of the core particles to produce a highly calcined calcium carbonate containing 5 to 95% calcium carbonate. This is what you get.

Hereinafter, the method for producing high-strength calcium carbonate according to the present invention will be illustrated by way of examples.

Example! To 5 tons of a suspension of 10% titanium oxide (commercially available rutile type) at 30°C was added 10% CaC++ at 30°C, which had been adjusted to have a solid content of 500 kg as CILCO3, with sufficient stirring. NH4OH and 20 (vol%),
20 ml/(ia(OR)z of carbon dioxide gas at 30°C
After introducing K at a rate of 0 minutes until the pH reaches 7, dehydration using a filter press, washing with water, drying at 100°C for 2 hours, pulverization using a hammer mill, and passing through a 150 mesh sieve to remove CaC0+.
1 ton of high-performance CaC0 powder containing 50% of CaCO was obtained.

Example 2 Highly pyrolytic CaCO containing 50% of CaCO
1 ton of 3 powder was obtained.

Example 3 A commercially available zinc white for rubber was used in place of the titanium oxide (rutile type) in Example 1, and Ca
Highly payable CILCO3 powder 1 containing 50% CO3
I got t.

Comparative Example 1 The same treatment as in Example 1 was performed using Ca(OH)2 obtained by hydrating CaO instead of CaCl2 and NHiOH used in Example 1, and using commercially available rutile titanium oxide as a bale. However, a different mixture of titanium oxide and CaCO3 was obtained, and the desired highly calcanic calcium carbonate coated with film-like fused calcium carbonate was not obtained.

Reference Example A cubic CaCo3 with a side of Ω and 2#Lm, which is currently thought to exhibit the best concealment property, was used as a comparison sample.

The results of the pigment ring resistance test for the high bay CaC0z of Example 1 are as follows: 1) Trial 4 ■ CaCO3 obtained in Example 1 ■ - Cubic CaCO3 with side length of 0.2 m ■ Conducted 50 parts of titanium oxide used in Example 1 and 0.2 m of cubic CaCO3
50 parts were stirred and mixed using a Hensel mixer. 2) Preparation of measurement sample Water was added to 100 parts of the above sample to make a paste with a concentration of 50%.

3) Measuring device P FUND CRYPTOMETER 4] Method for measuring hidden power The test was conducted according to JIS K-5101 pigment hidden power test.

5) Results As mentioned above, the high-strength carbon-resistant calcium obtained in Example 1 inherits the high-strength strength of the titanium oxide used as the core, and is simply a mixture of calcium carbonate and titanium oxide, with a high calcium carbonate content. It can be seen that it exhibits concealment performance that is several orders of magnitude better than that of the same amount.

(Effect of the invention) The hiding power of an inorganic white pigment is largely expressed by the refractive index of light possessed by the pigment, and it has recently been said from an optical standpoint that it depends on the diameter and shape of the particles and the properties of the particle surface. The improvement in the Ring Pei effect is not comparable to the Hidden Pei function obtained from the light refractive index of the material.

The products of this invention are used in paper manufacturing, paints, inks, and plastics.

It exhibits extremely excellent concealment performance as a pigment for rubber, chemical products, etc., and also makes effective use of rare resources such as titanium oxide. It's something you get.

[Brief explanation of the drawing]

FIG. 1 is an electron J11 microphotograph of Example 1. (40,000 times) FIG. 2 is an electron micrograph of Example 2. (40,000 times) Patent applicant: Yonejo Lime Industry Co., Ltd. Figure 1 Figure 2 / /i [Layer 4 (, ◇ [Corrections below line 15 on page 1 are as follows. April 1st, 1999

Claims (1)

[Claims] Highly hidden calcium carbonate using inorganic white pigments such as titanium oxide and zinc oxide as the core.