JPH0640715A - Production of spherical secondary particles of calcium silicate - Google Patents

Abstract

PURPOSE:To produce novel spherical secondary particles of useful calcium silicate crystals based on tobermorite crystals. CONSTITUTION:Milk of lime having >=5ml sedimentation volume is mixed with crystalline starting material for silicon dioxide so that the weight of water is regulated to >=15 times that of the solid materials and the resulting starting material slurry is brought into a hydro-thermal synthesis reaction while carrying out heating and stirring in reduced pressure to form the objective secondary particles of calcium silicate crystals based on tobermorite crystals.

Description

Detailed Description of the Invention

The present invention relates to calcium silicate spherical secondary particles and a method for producing the same, more specifically to calcium silicate spherical secondary particles having a tobermorite crystal as a main component and a method for producing the same, and the object thereof is the most stable against external force. To provide a secondary particle of a tobermorite crystal having a strong shape, that is, a spherical shape, in which the inside of the sphere is rough or hollow so as to reduce the density of the spontaneously settled compact, and a method for producing the same. is there.

In the present specification, the term "spherical" includes not only a perfect spherical shape but also an elliptic shape, and at least a part of the surface thereof is uneven.

Calcium silicate compacts are industrially applied to various fields such as refractory heat insulating materials, adsorbents, building materials, etc. These have a high specific strength, which is characteristic of calcium silicate compacts, and fire resistance. It is an inorganic material that is expected to develop in various fields due to its high price, heat insulating property, light weight, high dielectric property and the like. It is believed that the main reason for its characteristic properties is the crystal morphology of calcium silicate and its aggregated state.

The inventors of the present invention have conducted extensive research on the production and structure of secondary particles in a state where the calcium silicate crystals are in a special aggregated state, and as a result, among the calcium silicate crystals, Tobermo Succeeded in developing a new spherical secondary particle composed mainly of Wright crystals and completed an invention based on it. Already Patent No. 986812 (Japanese Patent Publication No. 54-4968).
Was patented as. This patented invention relates to an aqueous slurry in which spherical secondary particles of tobermorite having a specific structure are uniformly suspended in water.
Tobermorite crystals having an outer diameter of about 0 to 150 μm are irregularly three-dimensionally entangled and formed.

The spherical secondary particles of the tobermorite crystal are simply dispersed in water, molded and dried to form a tobermorite crystal having a light weight and excellent strength which did not exist at the time of the patent application. It can manufacture the body. It is considered that this is because the molded body is formed in a state where the spherical secondary particles are connected to each other and are compressed and deformed. That is, it is considered to be based on the fact that the constituent elements of the molded body are composed of secondary particles having a spherical shape which is the most stable and strong shape against external force.

In addition to the above, the present inventors have developed and already applied for a new spherical secondary particle of a wollastonite group calcium silicate crystal different from the tobermorite crystal among the calcium silicate crystals ( JP-A-53-1
46997). The spherical secondary particles composed of the wollastonite group calcium silicate crystals have an outer diameter of 10 to 70 μm, and the structure of the secondary particles in which the crystals are aggregated is such that needle-like crystals of calcium silicate are irregular on the outer periphery of the sphere. Is a secondary particle having three-dimensionally closely entangled with each other to form a thin spherical shell, the inside of which is a hollow particle and the apparent density of which is 0.09 to 0.13 g / cm ³ ,
It has a characteristic structure in which the breaking load of one particle is 10 to 100 mg, and the density of the spontaneous sedimentation compact is very small. A molded body produced from a slurry in which the spherical secondary particles are dispersed in water is particularly lightweight and has extremely high strength. In this case, it is considered that the spherical secondary particles are hollow and have high strength. The outer shell of the spherical secondary particles is strong and has high strength because the acicular crystals of wollastonite calcium silicate are closely entangled with each other.

The inventors of the present invention have been conducting extensive research on calcium silicate, and in the subsequent research,
We have succeeded in the development of spherical secondary particles with a completely new structure consisting of tobermorite crystals. That is, the present invention provides "a secondary particle having a rough or hollow substantially spherical inner shape, which is composed of a calcium silicate crystal containing a tobermorite crystal as a main component, and has an outer diameter of 10 to 120 µm and a breaking load of 100 mg.
Hereinafter, the calcium silicate spherical secondary particles characterized by having a hollow ratio of 30% or less and a natural sedimentation molded body density of 0.12 g / cm ³ or less "and" lime milk having a sedimentation volume of 5 ml or more and crystalline A raw material slurry obtained by mixing and preparing a silicic acid raw material so that the amount of water is 15 times by weight or more relative to the solid content is subjected to hydrothermal synthesis reaction while heating and stirring under pressure, and tobermorite crystals are the main components. And a method of producing spherical secondary particles of calcium silicate characterized by producing secondary particles of calcium silicate crystals.

The most basic conventional method for producing spherical secondary particles composed of calcium silicate crystals is, for example, the above-mentioned Japanese Patent No. 986.
As shown in No. 812, a raw material slurry prepared from a silicic acid raw material, a lime raw material, and water is heated by stirring and pressurizing to produce a synthetic reaction, and spherical secondary particles obtained by this method. Irrespective of the type of the calcium silicate crystals, there are almost no cavities inside, or even if they exist, the density of spontaneous sedimentation compacts is high. However, when producing spherical secondary particles of wollastonite calcium silicate as a type of calcium silicate crystal in this production method, it has an extremely excellent dispersion stability, which has never been used as a lime raw material at this time. It has been found by the present inventors that when lime milk is used and a crystalline silicic acid raw material is selectively used as the silicic acid raw material, hollow particles can be obtained with extremely light weight, and it has already been described above. It is filed as Sho 53-146997.

Then, the following studies have been made clear by the subsequent studies by the present inventors. JP-A-53-14699
The same operation as in the case of wollastonite group calcium silicate crystals was performed after the same operation was performed, conceived to produce spherical secondary particles composed of tobermorite crystals using the same raw material as No. 7. It was found that spherical secondary particles were not obtained, but spherical secondary particles having a coarser amount of tobermorite were obtained inside. The present invention has been completed based on this new finding.

The spherical secondary particles composed of the tobermorite crystal of the present invention are characterized by the following points. (1) First, a case where a tobermorite crystal is contained as a main component and this is used alone and a case where another calcium silicate crystal, for example, a zonotorite crystal is mixed with this is included. The term "tobermorite" is used below, including the case where they are mixed. (2) In the secondary particles of the present invention, it is observed that the tobermorite crystals are three-dimensionally entangled under an electron microscope or an optical microscope, and the secondary particles have a substantially spherical shape with an outer diameter of 10 to 120 μm. Is presenting. The outer diameter is measured by the following method. <Method of measuring outer diameter of secondary particles> 100 photographed by reflected light
The direction diameter was measured from an optical micrograph of spherical secondary particles mainly composed of doubled tobermorite crystals, and the range of particle diameter and the average particle diameter (median diameter) were obtained. FIG. 1 showing a 100 × optical micrograph of the secondary particles of the present invention in Example 1 to be described later shows that the secondary particles of the present invention are spherical and have an outer diameter of about 1
It can be seen that the average particle size is 0 to 120 μm and the average particle size is 38 μm. (3) The secondary particles of the present invention are characterized in that the breaking load of each particle is 100 mg or less. This breaking load is the packing density of the secondary particle structure, especially the tobermorite crystal,
It is considered to be related to the outer diameter of the secondary particles and their apparent density. For example, when the packing density of calcium silicate crystals in the outer shell of spherical secondary particles is small and coarse, the secondary particles do not break even under a relatively large load, and only tend to flatten due to compression. The so-called deformation resistance is small. On the other hand, the secondary particles of the present invention, such as those having a coarse or slightly hollow interior, have a large deformation resistance and therefore are hardly deformed under a load, but the breaking load per one is within a certain range of 100 mg or less. When the load exceeds a certain value within this range, it has the property of rapidly cracking and breaking, and does not exhibit the above flattening.

The above-mentioned breaking load means a load at which a crack is generated in at least a part of the spherical shell of the secondary particles when the load is applied to the spherical secondary particles of calcium silicate crystals. For example, the breaking load is 10 to 100 mg means that when a load is applied to the secondary particles, the secondary particles have a spherical shell of the secondary particles when a constant load of 10 to 100 mg is applied. It means that at least a part will be cracked, and the breaking load is 1000m.
The term "g" means that at least a part of the spherical shell of the secondary particles is cracked when a load of 1000 mg is applied. <Measurement Method of Breaking Load> The three secondary particles are placed on a slide glass in an equilateral triangle shape, a cover glass is placed on the slide glass, and the load is applied on the cover glass to observe with a 600 × optical microscope. It is measured by observing whether or not a crack occurs in a part of the spherical shell of the secondary particle, and is expressed by a load when the crack occurs. (4) The inside of the spherical secondary particles of the present invention is coarse or hollow, and the hollow ratio is 30% or less. Here, the hollow ratio is measured by the following method.

A part of the spontaneous sedimentation molded product was cut out, fixed with Canadian balsam (manufactured by Yoneyama Chemical Industry Co., Ltd.), and then polished, and then the Canadian balsam was removed with xylene to obtain a polished sample. This sample was photographed with a scanning electron microscope, the radius (γ) and the radius (γ ') of the hollow portion were measured from the cross section of the spherical secondary particles, and the hollow ratio was obtained from the following formula.

[0012]

[Chemical 1] The hollow ratio of 30% or less indicates that the hollow part is not particularly large even if the inside of the spherical secondary particles is hollow. Moreover, the case where small hollow portions are present everywhere and the so-called inside is rough is also included.

The inside of the spherical secondary particles shown in FIG. 3 is coarse and the hollow ratio is 0%, and the hollow ratio of the spherical secondary particles shown in FIG. 4 is 0 to 25%. .

For example, the hollow secondary particles composed of wollastonite group calcium silicate crystals described in Examples of JP-A-53-146997 have a hollowness of 60% or more, which is basically the same as the spherical secondary particles of the present invention. Have different structures. (5) The density of the spontaneously-precipitated compact of the secondary particles of the present invention is 0.
12 g / cm ³ or less, preferably 0.10 g / cm ³ or less. The density of the spontaneous sedimentation molded body was measured by the following method.

Slurry 20 in a 300 cc tall beaker
0 cc and 0.4 cc of nonionic and anionic surfactants (Granup NF-50, Sanyo Kasei Co., concentration 20%) were added and mixed, and the mixture was allowed to stand for 48 hours to spontaneously settle and then 10
It was dried at 0 ° C. for 48 hours to obtain a spontaneous sedimentation molded body. The volume and weight of this were measured to determine the density.

The fact that the density of this natural sedimentation molded product is low means that the spherical secondary particles themselves are considerably lightweight, and the secondary particles have a density of about 0.1 g / cm ³ and a practical strength. It can be manufactured. For example, the spherical secondary particles of the tobermorite crystals described in Japanese Patent No. 986812 have a high spontaneous sedimentation compact density, and therefore the density of the secondary particles of the known tobermorite crystals is 0.
It is not possible to manufacture a molded body of about 1 g / cm ³ . (6) The average apparent density of the secondary particles of the present invention is about 0.14.
~ 0.21 g / cm ³ , mainly 0.16 to 0.2
It is in the range of 0 g / cm ³ and is fairly lightweight.
However, the above average apparent density is measured by the following method. <Measurement Method of Average Apparent Density> The slurry of the tobermorite crystal was replaced with water in the slurry by acetone to obtain 90
Dry at 24 ° C. for 24 hours to make spherical secondary particles into powder without damage. This powder Wg is measured and placed in a beaker. Next, use a buret to impregnate the spherical secondary particles with water, and read the amount of water just when the spherical secondary particles were impregnated with water (when the viscosity of the spherical secondary particles suddenly increased) as Vml. To do. From this measurement, the average apparent density (ρ) of the spherical secondary particles was calculated by the following formula.

[0017]

[Chemical 2] However, ρt is the true specific gravity of Tobermorite, which is 2.576.
Is.

The spherical secondary particles of the present invention are manufactured, for example, by the following method.

Lime milk having a sedimentation volume of 5 ml or more, preferably 7 ml or more, and silicic acid mainly containing crystalline are mixed so that the amount of water with respect to the solid content is 15 times (weight) or more to form a raw material slurry. By performing a hydrothermal synthesis reaction while heating and stirring under pressure, a slurry of the spherical secondary particles of the present invention composed of mixed crystals of tobermorite or zonotolite containing this as a main component can be obtained. At this time, the sedimentation volume of 5 ml or more means that 50 ml of lime milk prepared by adjusting the solid content ratio of water to lime 120 times is put in a cylindrical container having a diameter of 1.3 cm and a volume of 50 ml or more, and allowed to stand for 20 minutes. The volume of lime settled is shown in ml. In order to obtain extremely well-dispersed lime milk having a sedimentation volume of 5 ml or more and having an excellent suspending property, quick lime is dissolved in warm water having a temperature higher than normal temperature with thorough stirring.
In order to obtain a particularly high sedimentation volume, it can be achieved by raising the slaking temperature, rapidly stirring with a homomixer, or stirring for a long time.

The silicic acid raw material used as the other raw material may be mainly composed of fine particles of crystalline silicic acid having an average particle size of 1 to 20 μm, preferably 10 μm or less. As the crystalline silicic acid, one having a slightly high content of Al ₂ O ₃ can be used, for example, one containing about ₂ % of Al ₂ O ₃ can also be used. 90% of the purity is SiO ₂
The above are commonly used.

The molar ratio of lime and silicic acid is preferably 0.70 to 0.95 (Ca).
O / SiO ₂ molar ratio) It is preferably about 0.75 to 0.90.

These lime milk and the silicic acid raw material are mixed to make the ratio of water to solid content 15 times or more, preferably 18 to 30 times. The raw material slurry thus obtained is then subjected to a hydrothermal synthesis reaction while heating and stirring under pressure. Reaction conditions such as pressure, temperature and stirring speed at this time are appropriately determined depending on a reaction container, a stirrer and the like used for the reaction. The hydrothermal reaction condition is usually performed when the saturated steam pressure is 5 kg / cm ² or more. For example, in the case of 12 kg / cm ² , 191 ° C., 10 kg / cm ²
It is about 183 ° C. in cm ² . The reaction time can be shortened by increasing the temperature and pressure, but economically the reaction time is preferably short, but considering the safety during operation, it is preferably within 10 hours, for example, 3 hours at 12 kg / cm ² . It takes about 6 hours at 8 kg / cm ² .

The agitation during the hydrothermal synthesis reaction is appropriately determined according to the raw materials used, the reaction vessel, the reaction conditions and the like. For example, when synthesizing under a condition of 12 kg / cm ² and 191 ° C. in a reactor having a diameter of 150 mm and a capacity of 31 using a stirring blade, the stirring speed is 100 r. p. About m is enough. Examples of the stirring operation include various stirring operations of rotating the reactor itself, vibrating it, and injecting a gas or a liquid. The hydrothermal reaction of the present invention may be a batch type reaction or a continuous reaction, and when the continuous reaction is performed, the synthetic slurry (calcium silicate crystal slurry) in which the raw material slurry is continuously pressed into the reaction vessel and the reaction is completed is performed under normal pressure. It should be discharged. Secondary particles need to be kept intact during this discharge. Alternatively, the water ratio of the raw material slurry may be reduced to cause the reaction in the reaction vessel, and after the reaction, a predetermined amount of water may be pressed and discharged.

Upon synthesizing the calcium silicate, a reaction accelerator, a catalyst and the like can be added appropriately, and a precipitation inhibitor can also be added. Examples of these include various salts of alkalis and alkali metals such as caustic soda and caustic potash, and also inorganic fibers such as asbestos and ceramic fibers.

By the above hydrothermal synthesis reaction, a slurry in which a large number of spherical secondary particles of the present invention composed of tobermorite crystals are dispersed in water is obtained. The powder of the tobermorite spherical secondary particles of the present invention can be obtained by drying this slurry without damaging the shape of the secondary particles.
A powder of wollastonite spherical secondary particles can be obtained by firing the slurry or the powder at 800 ° C. or higher so as not to impair the shape of the secondary particles.

The slurry in which the spherical secondary particles of the present invention are dispersed in water can be molded into a desired shape by molding the slurry into a desired shape and simply drying. The amount of water at this time may be appropriately determined within a wide range, but is usually about 3 to 50 times, preferably about 5 to 30 times the solid content.

A lightweight and high-strength tobermorite compact can be produced from a slurry in which the spherical secondary particles of the present invention are dispersed or suspended in water.

In the present invention, various reinforcing additives can be added to the above-mentioned slurry, if necessary. A wide variety of reinforcing additives can be used in this case, and representative examples thereof include pulp, hemp, various organic or inorganic synthetic and natural fibers, cement, clay, gypsum,
Examples include silica sand, diatomaceous earth, perlite, water glass, colloidal silica, alumina sol, lithium silicate, starch, and resin. As the organic fibers, natural fibers such as pulp and hemp, and various synthetic fibers such as nylon and tetron can be used, and as the inorganic fibers, asbestos, silica fiber, glass fiber, rock wool, graphite fiber, various whiskers and the like can be used. . In addition, reinforcing bars, wire mesh, etc. can also be used. By using these various reinforcing additives, it is possible to further improve the strength, heat resistance, hardness, etc. of the molded article of the object, depending on the type of the reinforcing additive.

The tobermorite molded product obtained from the tobermorite spherical secondary particles of the present invention has the following excellent properties as compared with the conventional tobermorite molded product produced from the conventional tobermorite spherical secondary particles. It has features. A A molded body having a density of about 0.1 g / cm ³ has a practical bending strength of 3 kg / cm ² or more. It should be noted that conventional tobermorite spherical secondary particles cannot be used to produce a lightweight molded body of about 0.1 g / cm ³ , and a tobermorite molded body of about 0.1 g / cm ³ is a spherical secondary particle of the present invention. It will only be possible with the development of particles. Despite being made of B tobermorite, it has high heat resistance, and the linear shrinkage rate is 2% or less even when heated to 850 ° C. C preferred orientation, especially bulk density of 0.3 g / cm ³
As a result, the degree of orientation is large. The degree of preferential orientation is measured by the following method.

A part of the molded body is sampled and finely pulverized to prepare a non-oriented powder sample, while another sample having a plane perpendicular to the pressing direction is prepared from the molded body (oriented sample).

Next, the X-ray diffraction intensities of the (002) and (220) planes of the two samples of the tobermorite crystals are measured.

The preferred orientation degree (P) is

[0033]

[Chemical 3] Is given by

Here, I (002) and I (220) are diffraction intensities of the non-oriented powder sample, and I '(002) and I' (22).
0) is the diffraction intensity of the oriented sample.

The spherical secondary particles of the present invention have an extremely low apparent density and a high heat resistance, and by suspending them in water or a solution, a molded body can be easily formed. It is extremely suitable for fire-resistant building materials and heat insulating materials, and powders comprising the secondary particles include fillers, various adsorbents, deodorants, agricultural chemicals, paints, toothpaste powders, pigments, catalyst carriers, and various chemicals. There are applications such as carriers.

[0036]

EXAMPLES The features of the present invention will be described below with reference to examples. In the following examples, "parts or%" means "parts by weight" or "% by weight" unless otherwise specified.

[0037]

Example 1 42.25 parts of quicklime (CaO 95.0%) was soaked in 507 parts of hot water at 80 ° C. and dispersed in water for 3 minutes with a homomixer to obtain a lime milk having a sedimentation volume of 19.
It was 9 ml. Silica powder (SiO ₂ 97.37%, Al ₂ O ₃ 0.99) with an average particle diameter of about 9 μm was added to the lime milk.
%) 53.21 parts were added and the total amount of water was mixed to be 22 times the solid content by weight to obtain a raw material slurry, which was saturated water vapor pressure 12 kg / cm ² , temperature 191 ° C. and volume 30.
Rotation speed of 17 in an autoclave of 00 cc and an inner diameter of 15 cm
4r. p. The hydrothermal synthesis reaction was performed for 3 hours while rotating the stirring blade at m to obtain a crystal slurry. When this crystal slurry was dried at 100 ° C. for 24 hours and subjected to X-ray diffraction analysis, it was confirmed to be tobermorite crystals. When this crystal slurry was dried on a slide glass and observed with an optical microscope, spherical secondary particles having an average outer diameter of 38 μm were observed as shown in FIG. Further, a surfactant was added to the slurry and mixed, and the mixture was allowed to stand for 48 hours for spontaneous sedimentation and then this was mixed with 10
A part of the spontaneous sedimentation molded product obtained by drying at 0 ° C. for 48 hours was cut out, fixed with Canadian balsam, and then polished, and then the above Canadian balsam was removed with xylene to obtain a polished sample. When this sample was observed with a scanning electron microscope, it was found that the tobermorite crystals roughly aggregated to form spherical secondary particles as shown in FIG.

When the secondary particles are dispersed and observed with an electron microscope, the length is 0.1 to 10 μm as shown in FIG.
m, a plate crystal with a width of 0.1 to 2 μm and a length of 0.1 to 10 μ
m, and needle-like crystals with a width of 0.05 to 0.5 μm were observed.

The characteristics of the secondary particles are shown in Table 1.

[0040]

[Table 1]

[0041]

Reference Example 1 The preferred orientation degree of the molded product obtained by press-molding the crystal slurry obtained in Example 1 and drying at 120 ° C. for 20 hours is as shown in Table 2.

[0042]

[Table 2] Then, 7 parts of glass fiber, 5 parts of pulp and 3 parts of Portland cement as an additive are added to 85 parts (solid content) of the above crystal slurry, and press-molded in the same manner, and at 20 ° C. for 20 minutes.
It was dried for an hour to obtain a molded body. The physical properties of the obtained molded product are shown in Table 3.

[0043]

[Table 3]

[0044]

Example 2 41.42 parts of quicklime (CaO 95.1%) was dissolved in 497 parts of hot water at 80 ° C. and dispersed in water with a homomixer for 5 minutes to obtain a lime milk having a sedimentation volume of 17.
It was 5 ml. The lime milk has an average particle size of about 8.5 μm.
Silica powder (SiO ₂ 94.03%, Al ₂ O ₃ 2.3
7%) 54.04 parts to make the total amount of water 22% of solids.
A raw material slurry was obtained by mixing so that the weight of the raw material slurry was 12 kg / cm ² , the temperature was 191 ° C., and the volume was 3
Rotation speed of 1 in an autoclave with 000 cc and an inner diameter of 15 cm
74r. p. The hydrothermal synthesis reaction was performed for 3 hours while rotating the stirring blade at m to obtain a crystal slurry. When this crystal slurry was dried at 100 ° C. for 24 hours and subjected to X-ray diffraction analysis, it was confirmed to be tobermorite crystals. When this crystal slurry was dried on a slide glass and observed with an optical microscope, spherical secondary particles having an average outer diameter of 52 μm were recognized.
Further, a surfactant was added to and mixed with the slurry, allowed to stand for 48 hours for spontaneous precipitation, and then dried at 100 ° C. for 48 hours to cut out a part of the spontaneous precipitation molded body, which was fixed with Canadian balsam. Then, after polishing this, the above Canadian balsam was removed with xylene to obtain a polishing sample.
When this sample was observed with a scanning electron microscope, it was found that the tobermorite crystals were roughly aggregated and spherical secondary particles having a hollow inside were formed as shown in FIG.

When the secondary particles are dispersed and observed by an electron microscope, plate-like crystals having a length of 0.1 to 10 μm and a width of 0.1 to 2 μm and a length of 0.1 to 10 μm and a width of 0.05 to 0 are obtained. .5
Needle-like crystals of μm were observed.

The characteristics of the secondary particles are shown in Table 4.

[0047]

[Table 4]

[0048]

Reference Example 2 The crystal orientation of the crystal slurry obtained in Example 2 was press-molded and dried at 120 ° C. for 20 hours.

[0049]

[Table 5] Then, 7 parts of glass fiber, 5 parts of pulp and 3 parts of Portland cement as an additive were added to 85 parts (solid content) of the above crystal slurry, and press molding was carried out in the same manner, and at 20 ° C., 20
It was dried for an hour to obtain a molded body. The physical properties of the obtained molded product are as shown in Table 6.

[0050]

[Table 6]

[0051]

Example 3 45.56 parts of quick lime (CaO 95.6%) was dissolved in 547 parts of hot water at 80 ° C. and dispersed in water with a homomixer for 6 minutes to obtain a lime milk having a sedimentation volume of 28.
It was 0 ml. The lime milk has an average particle size of about 8.5 μm.
Silica powder (SiO ₂ 94.03%, Al ₂ O ₃ 2.3
7%) 59.44 parts to add the total amount of water to 20% of solids.
A raw material slurry is obtained by mixing so that the weight of the raw material slurry is 8 times the saturated vapor pressure of 8 kg / cm ² and the temperature of 175 ° C.
Rotation speed of 17 in an autoclave of 00 cc and an inner diameter of 15 cm
4r. p. The hydrothermal synthesis reaction was performed for 6 hours while rotating the stirring blade at m to obtain a crystal slurry. When this crystal slurry was dried at 100 ° C. for 24 hours and subjected to X-ray diffraction analysis, it was confirmed to be tobermorite crystals. When this crystal slurry was dried on a slide glass and observed with an optical microscope, spherical secondary particles having an average outer diameter of 45 μm were recognized. Further, a surfactant was added to and mixed with the slurry, allowed to stand for 48 hours for spontaneous precipitation, and then dried at 100 ° C. for 48 hours to cut out a part of the spontaneous precipitation molded body, which was fixed with Canadian balsam. Then, after polishing this, the above Canadian balsam was removed with xylene to obtain a polishing sample. Observation of this sample with a scanning electron microscope revealed that the tobermorite crystals aggregated coarsely to form spherical secondary particles.

When the secondary particles are dispersed and observed by an electron microscope, plate crystals having a length of 0.1 to 10 μm and a width of 0.1 to 2 μm and a length of 0.1 to 10 μm and a width of 0.05 to 0 are obtained. .5
Needle-like crystals of μm were observed.

The characteristics of the secondary particles are shown in Table 7.

[0054]

[Table 7]

[0055]

Reference Example 3 The crystalline slurry obtained in Example 3 was press-molded and dried at 120 ° C. for 20 hours.

[0056]

[Table 8] Then, 7 parts of glass fiber, 5 parts of pulp and 3 parts of Portland cement as an additive are added to 85 parts (solid content) of the above crystal slurry, and press-molded in the same manner, and at 20 ° C. for 20 minutes.
It was dried for an hour to obtain a molded body. The physical properties of the obtained molded product are as shown in Table 9.

[0057]

[Table 9]

[0058]

Example 4 45.83 parts of quick lime (CaO 95.0%) was dissolved in 550 parts of hot water at 80 ° C. and dispersed in water for 7 minutes with a homomixer to obtain a sediment volume of 31.
It was 6 ml. The lime milk has an average particle size of about 1.6 μm.
Silica stone powder (SiO ₂ 95.1%, Al ₂ O ₃ 3.27)
%) 59.17 parts were added and the total amount of water was mixed so as to be 20 times the solid content by weight to obtain a raw material slurry, which was saturated water vapor pressure 12 kg / cm ² , temperature 191 ° C. and volume 30.
Rotation speed of 11 in an autoclave with 00 cc and an inner diameter of 15 cm
2r. p. The hydrothermal synthesis reaction was performed for 3 hours while rotating the stirring blade at m to obtain a crystal slurry. When this crystal slurry was dried at 100 ° C. for 24 hours and subjected to X-ray diffraction analysis, it was confirmed to be tobermorite crystals. When this crystal slurry was dried on a slide glass and observed with an optical microscope, spherical secondary particles having an average outer diameter of 24 μm were recognized. Further, a surfactant was added to and mixed with the slurry, allowed to stand for 48 hours for spontaneous precipitation, and then dried at 100 ° C. for 48 hours to cut out a part of the spontaneous precipitation molded body, which was fixed with Canadian balsam. Then, after polishing this, the above Canadian balsam was removed with xylene to obtain a polishing sample. When this sample was observed with a scanning electron microscope, it was found that the tobermorite crystals were coarsely aggregated and spherical secondary particles having a hollow inside were formed.

When the secondary particles are dispersed and observed by an electron microscope, plate-like crystals having a length of 0.1 to 10 μm and a width of 0.1 to 2 μm and a length of 0.1 to 10 μm and a width of 0.05 to 0 are obtained. .5
Needle-like crystals of μm were observed.

The characteristics of the above secondary particles are as shown in Table 10.

[0061]

[Table 10]

[0062]

Reference Example 4 The crystal orientation obtained in Example 4 was press-molded and dried at 120 ° C. for 20 hours.

[0063]

[Table 11] Then, 7 parts of glass fiber, 5 parts of pulp and 3 parts of Portland cement as an additive are added to 85 parts (solid content) of the above crystal slurry, and press-molded in the same manner, and at 20 ° C. for 20 minutes.
It was dried for an hour to obtain a molded body. The physical properties of the obtained molded product are as shown in Table 12.

[0064]

[Table 12]

[0065]

[Example 5] 42.23 parts of quicklime (CaO 95.0%) was soaked in 507 parts of hot water at 80 ° C and dispersed in water with a homomixer for 6 minutes to obtain a lime milk having a sedimentation volume of 26.
It was 0 ml. The lime milk has an average particle size of about 1.6 μm.
Silica powder (SiO ₂ 95.01%, Al ₂ O ₃ 3.2)
7%) 53.23 parts were added to bring the total amount of water to 22% of solids.
A raw material slurry was obtained by mixing so that the weight of the raw material slurry was 12 kg / cm ² , the temperature was 191 ° C., and the volume was 3
Rotation speed of 1 in an autoclave with 000 cc and an inner diameter of 15 cm
12r. p. The hydrothermal synthesis reaction was performed for 5 hours while rotating the stirring blade at m to obtain a crystal slurry. When this crystal slurry was dried at 100 ° C. for 24 hours and analyzed by X-ray diffraction, it was confirmed that the tobermorite crystals were mixed with a small amount of zonotolite crystals. When this crystal slurry was dried on a slide glass and observed with an optical microscope, spherical secondary particles having an average outer diameter of 31 μm were recognized. Further, a surfactant was added to and mixed with the slurry, allowed to stand for 48 hours for spontaneous precipitation, and then dried at 100 ° C. for 48 hours to cut out a part of the spontaneous precipitation molded body, which was fixed with Canadian balsam. Then, after polishing this, the above Canadian balsam was removed with xylene to obtain a polishing sample. When this sample was observed with a scanning electron microscope, it was found that the tobermorite crystals and a small amount of zonotolite crystals were roughly aggregated and that spherical secondary particles having a hollow inside were formed.

The characteristics of the secondary particles are shown in Table 13.

[0067]

[Table 13]

[0068]

Reference Example 5 The crystal orientation slurry obtained in Example 5 was press-molded and dried at 120 ° C. for 20 hours.

[0069]

[Table 14] Then, 7 parts of glass fiber, 5 parts of pulp and 5 parts of Portland cement as an additive are added to 85 parts (solid content) of the above crystal slurry, and press molding is carried out in the same manner, followed by heating at 120 ° C. for 20 minutes.
It was dried for an hour to obtain a molded body. The physical properties of the obtained molded product are as shown in Table 15.

[0070]

[Table 15]

[0071]

Example 6 42.25 parts of quick lime (CaO 95.0%) was hydrated in 507 parts of hot water at 80 ° C. and dispersed in water for 2 minutes with a homomixer to obtain a sediment volume of 8.1.
It was ml. Silica powder with an average particle size of about 9 μm (SiO ₂ 92.37%, Al ₂ O ₃ 0.99%) is added to the lime milk.
A raw material slurry was obtained by adding 53.21 parts and mixing the total amount of water to be 22 times the weight of the solid content, and saturating a steam pressure of 12 kg / cm ^{2 at} a temperature of 191 ° C. and a volume of 3000.
Rotation speed 174 in an autoclave with cc and inner diameter of 15 cm
r. p. The hydrothermal synthesis reaction was performed for 3 hours while rotating the stirring blade at m to obtain a crystal slurry. 1 of this crystal slurry
When it was dried at 00 ° C. for 24 hours and analyzed by X-ray diffraction, it was confirmed to be tobermorite crystals. When this crystal slurry was dried on a slide glass and observed by an optical microscope, spherical secondary particles having an average outer diameter of 47 μm were recognized. Further, a surfactant was added to the slurry, mixed, allowed to stand for 48 hours for spontaneous sedimentation, and then dried at 100 ° C. for 48 hours to cut out a part of the spontaneous sedimentation molded body, which was fixed with Canadian balsam. Then, after polishing this, the above Canadian balsam was removed with xylene to obtain a polishing sample. Observation of this sample with a scanning electron microscope revealed that the tobermorite crystals aggregated coarsely to form spherical secondary particles.

When the secondary particles are dispersed and observed by an electron microscope, plate-like crystals having a length of 0.1 to 10 μm and a width of 0.1 to 2 μm and a length of 0.1 to 10 μm and a width of 0.05 to 0 are obtained. .5
Needle-like crystals of μm were observed.

The characteristics of the above secondary particles are as shown in Table 16.

[0074]

[Table 16]

[0075]

Reference Example 6 The crystal orientation slurry obtained in Example 6 was press-molded and dried at 120 ° C. for 20 hours.

[0076]

[Table 17] Then, 7 parts of glass fiber, 5 parts of pulp and 3 parts of Portland cement as an additive are added to 85 parts (solid content) of the above crystal slurry, and press-molded in the same manner, and at 20 ° C. for 20 minutes.
It was dried for an hour to obtain a molded body. The physical properties of the resulting molded product are shown in Table 18.

[0077]

[Table 18]

[0078]

[Comparative Example] The sedimentation volume of lime milk obtained by soaking 42.25 parts of quick lime (CaO 95.0%) in 507 parts of hot water at 80 ° C was 4.0 ml. The above lime milk has an average particle size of about 9
μm silica stone powder (SiO ₂ 97.37%, Al ₂ O
₃ 0.99%) 53.21 parts were added and the total amount of water was mixed to be 22 times by weight of the solid content to obtain a raw material slurry, which was saturated steam pressure 12 kg / cm ² , temperature 191.
At an autoclave with a volume of 3000 cc and an inner diameter of 15 cm at 174 rpm. p. The hydrothermal synthesis reaction was performed for 3 hours while rotating the stirring blade at m to obtain a crystal slurry. When this crystal slurry was dried at 100 ° C. for 24 hours and subjected to X-ray diffraction analysis, it was confirmed to be tobermorite crystals. When this crystal slurry was dried on a slide glass and observed with an optical microscope, spherical secondary particles having an average outer diameter of 48 μm were recognized. Further, by adding and mixing a surfactant to the slurry,
Allow it to stand for 48 hours to let it settle at room temperature and then add it to 100 ° C
A part of the spontaneous sedimentation molded product obtained by drying for 8 hours was cut out, fixed with Canadian balsam, and then polished, and then the above Canadian balsam was removed with xylene to obtain a polished sample. Observation of this sample with a scanning electron microscope revealed that the tobermorite crystals were densely aggregated to form spherical secondary particles.

When the secondary particles are dispersed and observed by an electron microscope, plate-like crystals having a length of 0.1 to 10 μm and a width of 0.1 to 2 μm and a length of 0.1 to 10 μm and a width of 0.05 to 0 are obtained. .5
Needle-like crystals of μm were observed.

The characteristics of the secondary particles are as shown in Table 19.

[0081]

[Table 19]

[0082]

[Reference Example] The crystal slurry obtained in Comparative Example was press-molded,
The preferred orientation degree of the molded product obtained by drying at 120 ° C. for 20 hours is as shown in Table 20.

[0083]

[Table 20] Then, 7 parts of glass fiber, 5 parts of pulp and 3 parts of Portland cement as an additive are added to 85 parts (solid content) of the above crystal slurry, and press-molded in the same manner, and at 20 ° C. for 20 minutes.
It was dried for an hour to obtain a molded body. The physical properties of the obtained molded product are as shown in Table 21.

[0084]

[Table 21]

[Brief description of drawings]

FIG. 1 is a 100 × optical micrograph of spherical tobermorite crystal secondary particles of the present invention in Example 1.

FIG. 2 is an electron micrograph at 7500 times in which the particles of Example 1 are dispersed.

FIG. 3 is a scanning electron micrograph (600 times) of a polished surface of a spontaneous sedimentation molded article of Example 1.

FIG. 4 is a scanning electron micrograph (600 times) of a polished surface of a spontaneous sedimentation molded article of Example 2.

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[Procedure amendment]

[Submission date] April 12, 1993

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a 100 × optical micrograph showing the particle structure of spherical tobermorite crystal secondary particles of the present invention obtained in Example 1.

FIG. 2 shows a crystal structure of a primary particle in which spherical tobermorite crystal secondary particles obtained in Example 1 are dispersed 7500
It is a double electron microscope photograph.

FIG. 3 is a scanning electron micrograph (600 times) showing the texture of the polished surface of the spontaneously-precipitated compact obtained in Example 1.

FIG. 4 is a scanning electron micrograph (600 times) showing the structure of the polished surface of the spontaneously-precipitated molded article obtained in Example 2.

Claims (1)

[Claims] 1. A raw material slurry obtained by mixing and preparing lime milk having a sedimentation volume of 5 ml or more and a crystalline silicic acid raw material so that the amount of water with respect to the solid content is 15 times by weight or more while heating and stirring under pressure. A method for producing spherical secondary particles of calcium silicate, which comprises performing a hydrothermal synthesis reaction to generate secondary particles of calcium silicate crystals containing a tobermorite crystal as a main component.