JPS61201616A - Production of swelling mica - Google Patents

Abstract

PURPOSE:To produce the swelling mica having such the characteristics that it swells by absorbing the water content contained in air at the comparatively low heating temp. and also in a short heating time by adding lithium fluoride of the specified weight ratio to the talc powder, mixing it with each other and heat-treating it. CONSTITUTION:By weight ratio >=15% lithium fluoride is added to the talc powder and mixed with each other. The aimed swelling mica shown in 2LiF.3 MgO.4SiO2 is obtained by heat-treating the mixture at 650-780 deg.C. Since this swelling mica has such the properties that it absorbs water, swells and finally becomes the extremely fine ultrapulverized material, the nonflammable paper and the nonflammable paint can be produced by using this swelling mica as a basic material and mixing the other necessary inorganic material and organic material.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is based on the special property of mica, that is, it absorbs water and swells when placed in water or even in humid air. The present invention relates to a method for producing mica.

This type of swellable mica absorbs water and swells, which interspecies and eventually becomes extremely fine particles.
Using this as a basic material, composite materials with other inorganic and organic materials are being considered for many uses, including non-flammable paper and non-flammable paint.

<Prior art and its disadvantages> Conventionally, methods for producing fluorine-type mica include the so-called melting method in which silica magnesia, alumina, and fluoride are melted at a high temperature of 1300° C. or higher and slowly cooled, and feldspar.

A so-called solid-state reaction method was used in which olivine 1 quartz and fluoride were mixed, gradually heated, and reacted at 1000°C or higher for 2 to 24 hours, but the reaction temperature was too high and the reaction time was too long. There were drawbacks such as.

The inventors of the present invention proposed a method for solving the above-mentioned drawbacks.
The method disclosed in Japanese Patent Publication No. 9-1215 was developed, making it possible to lower the reaction temperature and shorten the processing time.

However, even in the method described in Japanese Patent Publication No. 59-1215, it has been found that when the reaction holding time is shortened, it is actually necessary to adjust the temperature to 1000 DEG C. or higher.

Means for Solving the Problems In the present invention, the reaction temperature is lowered (and the holding time is shorter), and the resulting mica is 2LiF.3 having so-called swelling properties.
The purpose is to provide a method that produces MgO/SiO2, and its gist is to add and mix at least 15% lithium fluoride based on the weight of talc powder, and to heat-treat the mixture at 650 to 780°C. *Characteristics) 2LiF4MgO・4SiOz tt
RowEiI! l! This is a method for producing I-type mica.

2LiF・3MgO・5i0 obtained by the method of the present invention
Mica, which has a composition of 2, has the property of easily absorbing moisture from the air into its crystals and swelling at room temperature.
This can be confirmed by measuring the thickness in the C-axis direction using the X-ray powder method.

<Examples and effects> The present invention will be described in detail below with reference to Examples.

11. Talc was ground for 1 minute in a ball mill, mixed with 15% by weight of lithium fluoride, placed in a magnetic crucible, and heated at 650°C, 700°C, and 750°C in an electric furnace.
, 780° C. for 1 hour to obtain swellable mica.

The production rate of swelling mica was measured using the X-ray powder method, and the diffraction peak (2θ = 9.0 to 6) of swelling mica produced at each temperature was measured.
．． 5°) divided by the area of the peak of 100% produced mica. The results are shown in the graph of Figure 1, and it can be seen that swelling mica begins to form at 650°C and 750°C to 78°C.
It can be seen that the production rate is 100% up to 0°C.

In addition, as a result of measuring the mica produced at 780°C by the above method using the X-ray powder method, the thickness in the C-axis direction was d = 12.5.
It was confirmed that there was A0, and one molecule of water was coordinated between the layers, and when ethylene glycol treatment was performed to further examine the swelling property, it was confirmed that the d value increased to 1780.

This means that organic matter can easily enter between the layers, and it can be said that it has properties similar to montmorillonite.

- The mixing ratio of lithium fluoride to the same talcum as used in Example 1 was changed to 5% by weight, 10% by weight, 15% by weight, and 20% by weight, and the treatment temperature was also 700%. °C, 7
The graph in FIG. 2 shows the production rate of swelling mica when the temperature was changed for 1 hour at 50°C and 780°C. The production rate value in this case was determined in the same manner as in Example 1 above.

It can be seen from FIG. 2 that at least 15% by weight of lithium fluoride is required to obtain a sufficient amount of swellable mica.

Based on the results of the examples described above, in order to obtain a sufficient amount of swellable mica, the amount of lithium fluoride added to talc needs to be at least 15% by weight, and the temperature of the heat treatment is 650°C. The temperature above 780°C is 100% swellable mica, so there is no need to raise the temperature any higher; on the contrary, if you raise the temperature to just 9°C, the powder will sinter, and later The treatment temperature is preferably 650 to 780° C. since it involves complications such as the necessity of a pulverization step.

<Effects of the Invention> According to the method of the present invention, 2LiF/3MgO/4Si, which has the unique property of absorbing moisture in the air and swelling
This method has the advantage that swellable mica having a composition of 02 can be obtained at a relatively low temperature of 780° C. or lower and in a shorter holding time of about 1 hour than conventional methods.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between temperature and the production rate of swellable mica in the method of the present invention, and Figure 2 is a graph showing the relationship between the amount of LiF added and the production rate of swellable mica.

Claims (1)

[Claims] 1. Add and mix at least 15% lithium fluoride per weight to talc powder, and make the mixture 650-78% by weight.
2LiF/3Mg characterized by heat treatment at 0°C
A method for producing swellable mica represented by O.4SiO_2.