JPS6048449B2 - Method for producing γ-dicalcium silicate powder with large surface area - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing γ-dicalcium silicate powder having a large surface area.

Dicalcium silicate is Ca.

S.I.O. It is a compound with the molecular formula of, and has been studied as a component of cement. 4 for dicalcium silicate
It is said that there are four types of metamorphosis, namely α, α', β and γ types, among which γ type dicalcium silicate (hereinafter γ-
C.

(abbreviated as S) does not have hydraulic properties and was considered undesirable as cement. Therefore γ-C. Many studies have been conducted on preventing the generation of S. The inventor is γ-C. He discovered that it was effective as a stabilizer for chlorine-containing resins, discovered a method for producing it, and filed a patent application in 1984-6.
The application was filed under No. 0407. As a result of further study, the present inventors found γ-C. It has been found that the larger the surface area of S, the greater its ability to capture free chlorine, making it more effective as a stabilizer for chlorine-containing resins. Therefore, an object of the present invention is to provide a method for producing γ-C2S having a large surface area.

That is, the gist of the present invention is that 1 as calcium oxide after calcination.
00 parts by weight and 42.3 parts by weight to 53.6 parts by weight as silicon oxide
Production of γ-monosilicate dilime powder with a large surface area, characterized in that a mixture obtained by adding an alkali metal or alkaline earth metal chloride to a composition containing the following parts by weight is calcined and cooled. After the method and calcination, the composition should contain 1 part by weight of calcium oxide and 42.3 to 53.6 parts by weight of silicon oxide, and 0.5 to 15 parts by weight of titanium oxide and an alkali metal or alkali. A method for producing γ monosilicate dilime powder having a large surface area, which comprises firing and cooling a mixture obtained by adding an earth metal oxide.

In the present invention, a material containing calcium acetate and silicon oxide is used as a raw material.

It may contain volatile components in addition to calcium oxide and silicon oxide itself. The volatile components herein are those that have the property of volatilizing at the firing temperature, and include, for example, water, carbon dioxide, and the like. Therefore, as a substance containing calcium oxide, calcium oxide CaO
In addition, for example, calcium hydroxide Ca (0H). , calcium carbonate CacO3, and silicon oxide SIO. In addition, for example, silicic acid H. Si
Examples include O3. In the case of those containing calcium oxide and those containing silicon oxide, the silicon oxide content is 42.0 parts by weight per 100 parts by weight of calcium oxide after firing. Heel volume ~
The composition is mixed in a quantitative proportion of 53.6 parts by weight. Since γ monosilicate dicalcium has a molar ratio (theoretical value) of calcium oxide and silicon oxide of 2:1, the above molar ratio can be obtained as a raw material. Although it is most preferable to use a composition containing 100 parts by weight of silicon oxide, the silicon oxide composition may be deficient by about 21%, so that the weight ratio is 42.3 parts by weight to 53.3 parts by weight of silicon oxide to 100 parts by weight of calcium oxide.
6 parts by weight, and in the present invention, a composition that provides calcium trioxide and silicon oxide within the above range after firing is used. In the present invention, an alkali metal or alkaline earth metal chloride is added to the composition and mixed uniformly to form a mixture.

4. Chlorides of alkali metals or alkaline earth metals include:
Examples are sodium chloride, potassium chloride, lithium chloride,
Examples include calcium chloride and magnesium chloride, with calcium chloride and magnesium chloride being particularly preferred.

Although the amount used is not particularly limited, γ-C obtained when the amount used is too small. The same γ-C was obtained when the surface area of the S powder was small and too large. The surface area of the s powder tends to become smaller, and the chloride absorbs moisture and the particles tend to aggregate, making it difficult for the obtained γ-C2S to become a fine powder, especially when a large amount of magnesium chloride is added. Therefore, the amount of chloride added is 100 parts by weight of calcium oxide and 42.3 to 53 parts by weight of silicon fluoride after firing.
．． It is preferable to use 0.7 to 4 parts of the tumor, more preferably 2.8 to 3 parts of the tumor. In the present invention, the above-mentioned mixture is calcined, and the calcining temperature is generally 1000° C. or higher.

In order to obtain a fine powder, it is more preferable to sinter at a temperature of 1200 to 1450°C. Further, the firing time is not limited at all, and may be set so that the mixture is completely converted to γ-C2S, but generally 1 to 3 hours is sufficient.
For firing, an electric furnace, a heavy oil furnace, a gas furnace, etc. can be arbitrarily used. Next, when the fired mixture is allowed to cool naturally, the fired mixture is naturally pulverized during the solidification process, and a uniform and fine γ-C2S powder with a large surface area is obtained. Further, by adding a substance that gives titanium oxide after firing to the above-mentioned mixture, and then firing and cooling in the same manner, a uniform and fine γ-C with a large surface area can be obtained.

s powder is obtained. At this time, the material that provides titanium oxide may contain volatile components, and may be any material that produces titanium oxide during firing, that is, at a temperature of about 1000°C or higher, for example, titanium hydroxide T1. (0H).

etc. Therefore, as titanium oxide, rutile-type and anatase-type titania pigments, and powder of redstone can be used as they are, as well as titanium hydroxide and titanium oxide monohydrate H. TIO. It is preferable to use a method that produces as high a purity titanium oxide as possible during firing. The titanium oxide is provided by calcium oxide 10 in the aforementioned mixture.
0.5 to 15 parts by weight of titanium oxide is added to the tumor area, more preferably 0.5 to 5 parts by weight,
As the ratio of silicon oxide to calcium oxide decreases in the aforementioned mixture, it is preferred to increase the amount of titanium oxide.

It is preferable that the mixture obtained by adding the above-mentioned mixture and the material providing titanium oxide is thoroughly stirred to be uniformly dispersed.

Therefore, it is preferable to use substances b that provide calcium oxide, silicon oxide, titanium oxide, etc., and chlorides of alkali metals or alkaline earth metals, which have been previously made into fine powders. In addition to the volatile components, some other metal oxides may be mixed in as impurities in the mixture obtained by adding the above-mentioned mixture and a substance that provides titanium oxide.

The amount of metal oxide allowed varies depending on the type of metal oxide, but is generally 0.5% or less of the total amount of calcium oxide, silicon oxide, and titanium oxide. However, when titanium oxide is not added, iron oxide, aluminum oxide, magnesium oxide, etc. contained as impurities are contained in the obtained γ-C.

α'-C by making the particle size of the s powder large and irregular. S
and β-C. It is undesirable because it works to generate S.
．． Therefore, it is preferable that the amounts of iron oxide, aluminum oxide, and magnesium oxide mixed are kept as small as possible.
The manufacturing method of the present invention is as described above, and after calcination, an alkali metal or alkaline earth metal chloride is added to a composition that should contain calcium oxide and silicon oxide, followed by calcination and cooling to produce γ-C.

Since we are producing fine powder of γ-C, the particle size is very small and uniform, less than 40μ, and the surface is uneven and has a very large surface area. It is possible to obtain a fine powder of s. Also, by adding titanium oxide, the ratio of silicon oxide to calcium oxide is 2:1.
Even if it becomes smaller, it is completely converted to γ-C2S, and even if the mixture contains iron oxide, aluminum oxide, or magnesium oxide, if the content is 0.5% by weight or less, its adverse effects are suppressed. It is possible. Also produced γ-C.

Since S is naturally pulverized into fine particles when cooled, it is possible to make the product into a fine powder with a uniform particle size without mechanically pulverizing the product. γ
-C.

Since S powder has a very large surface area, it has a strong scavenging effect on free hydrogen chloride, and therefore has particularly excellent properties as a stabilizer for chlorine-containing resins. Next, the manufacturing method of the present invention will be explained with reference to Examples.

Note that the term "parts" hereinafter simply means "parts by weight."
Further, the particle size distribution was measured using a light transmission type particle size distribution analyzer (manufactured by Seishin Enterprise Co., Ltd.), and the specific surface area was measured by the BET method using a sorbtometer (manufactured by Perkin-Elmer Co., Ltd.).

Furthermore, the stability performance against chlorine-containing resins was measured using γ-
Add 5 parts of C2S powder, mix well, and use the resulting mixture to measure the time it takes for Congo red test paper to turn blue in an oil bath at 200°C according to JIS K6723 (thermal stability test). It was measured by measuring.
Examples 1 to 3 34 J parts of silica powder and 116.1 parts of calcium carbonate (CaO
65.1 parts in terms of conversion) and a predetermined amount of calcium chloride (5 parts in Example 1, m parts in Example 2, m parts in Example 3).
(2) was added and stirred and mixed to obtain a mixture.

The obtained mixture was supplied to an electric furnace and heated at about 1300°C for 2
Baked for an hour.

Immediately after firing, the fired product was taken out of the furnace and cooled in the air.
The fired product was naturally crushed into white powder during cooling.
The obtained white powder was passed through a wet sieve to remove extremely fine powder particles of several microns or less, and then measured by X-ray diffraction, and the measured values were consistent with pure γ-C2S. Further, when observed with an electron microscope, the surface was uneven, and the average particle size was about 15 microns, with most of the particles ranging from 5 to 30 microns. Also, the obtained γ-
C. The specific surface area and stability performance (time until Congo Red test paper turns blue) of S were measured and shown in Table 1. γ-C in comparison with a comparative example described below. The surface area of s increases,
It can be seen that the stability performance has improved by 5. Examples 4 and 5 Silica powder 34. 116.1 parts of calcium carbonate (CaO
A predetermined amount of magnesium chloride (50 parts for Example 4, ■ parts for Example 5) was added to a composition consisting of 65.1 parts (converted in terms of 65.1 parts) and 0.46 parts of titanium oxide, and the mixture was stirred and mixed to obtain a mixture. Ta.

The resulting mixture was fed into an electric furnace and fired at about 1350'C for 2 hours.

After firing, the fired product was taken out of the furnace at a high temperature and cooled in air, and the fired product spontaneously pulverized into a white powder during cooling. The obtained powder was passed through a wet sieve to remove extremely fine powder particles in the same manner as in Example 1, and then measured by X-ray diffraction, and the measured value was pure γ-C. It was consistent with s. In addition, the powder particles have unevenness on the surface,
The average particle size is approximately 15 microns, with the majority of particles being 5 to 3
It turned out to be 0 micron. Furthermore, as mentioned above,
γ-C. Even though the raw materials contain titanium oxide and chlorides such as magnesium chloride and calcium chloride other than the s-component and are fired, the powder crystals obtained as a result of firing are pure γ-C. The reason why the X-ray diffraction value matches that of After performing some action to increase the surface area, as the melt cools, most of it becomes γ-C. s are not incorporated into the crystal structure but are excluded from the system, and as a result, these additives produce γ-C. The two forms of very fine powder that adhere to the surface of the s particles are mixed in the generated powder, and when washed with water or thoroughly washed. This is thought to be because the separation makes it easier to remove. Further, the specific surface area and stability performance were measured and shown in Table 1.

2 Comparative Example 1 34 J parts of silica powder and 116.1 parts of calcium carbonate (CaO
(converted to 65.1 parts) and 3.6 parts of iron oxide were thoroughly stirred to obtain a mixture.

The resulting mixture was fired in the same manner as in Example 1, and the fired product was air cooled.

The fired product was naturally pulverized during cooling, but the resulting powder was brown in color. Most of the powder is γ-C.

s, but the surface of the particles was smooth, the particle size was uneven, and many particles of 50 microns or more were mixed in.
Comparative Example 2 34 parts of silica powder and 116.1 parts of calcium carbonate (CaO
(65.1 parts in terms of conversion) and 0.46 parts of titanium oxide were thoroughly stirred to obtain a mixture.

The resulting mixture was treated at 140 ml as in Example 1.
It was fired at 0°C and the fired product was air cooled.

The fired product was naturally crushed during cooling to obtain a white powder. The powder was γ-C in the same manner as in Example 1. s, the average particle size is about 15 microns, and most of the particles are 5 to
Although the particle size was found to be 30 microns, the surface of the particles was smooth. The obtained γ-C.

Claims (1)

[Claims] 1. Adding an alkali metal or alkaline earth metal chloride to a composition that should contain 100 parts by weight of calcium oxide and 42.3 to 53.6 parts by weight of silicon oxide after firing. A method for producing γ-dilime silicate powder having a large surface area, which comprises firing and cooling the obtained mixture. 2 Claim 1 in which the chloride is calcium chloride
Manufacturing method described in section. 3. The manufacturing method according to claim 1, wherein the chloride is magnesium chloride. 4. The manufacturing method according to claim 1, wherein the amount of chloride added is 0.7 parts by weight to 46 parts by weight. 5. The manufacturing method according to claim 1, wherein the incineration temperature is 1000°C or higher. 6. The manufacturing method according to claim 5, wherein the incineration temperature is 1200°C to 1450°C. 7 After firing, the composition should contain 100 parts by weight as calcium oxide and 42.3 parts by weight to 53.6 parts by weight as silicon oxide, and 0.5 parts by weight to 15 parts by weight as titanium oxide and an alkali metal or alkaline earth metal. 1. A method for producing γ-dilime silicate powder having a large surface area, which comprises firing and cooling a mixture obtained by adding a metal chloride. 8 Claim 7 in which the chloride is calcium chloride
Manufacturing method described in section. 9. The manufacturing method according to claim 7, wherein the chloride is magnesium chloride. 10. The manufacturing method according to claim 7, wherein the amount of chloride added is 0.7 parts by weight to 46 parts by weight. 11. The manufacturing method according to claim 7, wherein the firing temperature is 1000°C or higher. 12. The manufacturing method according to claim 11, wherein the firing temperature is 1200°C to 1450°C.