JP3048255B2 - Inorganic composite particles and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel inorganic composite particle. Specifically, an aggregate of inorganic fine particles is fixed to the pores of the porous inorganic particles formed of an aggregate of plate-like crystals,
It is an inorganic composite particle having a remarkably large micropore volume.

[0002]

2. Description of the Related Art Generally, porous inorganic particles (hereinafter simply referred to as "porous inorganic particles") composed of an aggregate of plate-like crystals such as basic magnesium carbonate and calcium silicate have a certain pore volume. However, the liquid adsorption speed is low and the liquid holding power is weak, causing problems in various applications. For example, when the particles are used as a filler for filling in paper, a filler for a coating material, or the like, there is a problem in that bleeding occurs in printing due to a low ink absorption speed.
This phenomenon is considered to be due to the small pore volume of the fine pores having a pore diameter of 200 Å or less of the porous inorganic particles.

Conventionally, as a method of increasing the volume of the fine pores of the porous inorganic particles, a method of changing the production conditions of the particles has been proposed, but the volume of the fine pores of the porous inorganic particles is increased only by the production conditions. However, it is difficult to obtain porous inorganic particles having a sufficiently large micropore volume. On the other hand, in order to increase the apparent specific gravity of basic magnesium carbonate, which is a kind of porous inorganic particles, a method of adding calcium chloride together with raw material magnesium chloride in a process of producing basic magnesium carbonate for carbonating magnesium chloride has also been proposed. ing. However, the basic magnesium carbonate produced by such a method, according to the experiments of the present inventors, although its apparent specific gravity is increased, the pores are filled with crystal particles of calcium carbonate having a large primary particle diameter inside the pores. In order to form a composite, not only the basic pore volume of the basic magnesium carbonate decreases, but also the volume of the target micropores hardly increases.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a porous inorganic particle composed of an aggregate of plate-like crystals, which has a large pore volume without reducing the total pore volume inherent in the porous inorganic particle. It is to provide inorganic particles.

[0005]

Means for Achieving the Object The present inventors have made intensive studies to achieve the above object and found that an aggregate of inorganic fine particles having a small primary particle diameter is fixed in the pores of the porous inorganic particles. As a result, the present inventors have found that the pores can be made finer due to the presence of aggregates of inorganic fine particles, and that the volume of the fine pores can be significantly increased without reducing the volume of the pores.

According to the present invention, there is provided a porous inorganic particle composed of an aggregate of plate-like crystals, and an aggregate of inorganic fine particles having a primary particle diameter of 50 to 5000 angstroms with respect to 100 parts by weight of the porous inorganic particle. 50 parts by weight are fixed inorganic composite particles.

[0007] The porous inorganic particles serving as the basic skeleton of the inorganic composite particles of the present invention are particles in which plate-like crystals form aggregates to form pores. The porous inorganic particles formed of such an aggregate of plate-like crystals are not particularly limited. Specific examples of the types of the porous inorganic particles include an aggregate of plate-like crystals made of basic magnesium carbonate, calcium silicate, magnesium silicate, and the like. The shape of the porous inorganic particles is not particularly limited, but a spherical shape is most preferable.

The inorganic composite particles of the present invention are obtained by fixing aggregates of inorganic fine particles in the pores of the porous inorganic particles. That is, by fixing the aggregate of the inorganic fine particles having a small primary particle diameter in or around the pores of the porous inorganic particles so as to limit the pore diameter of the porous inorganic particles, the fine pores by the aggregated particles are fixed. With the increase of the pores, the pores of the porous particles restricted by the aggregated particles can be increased, so that the pores of the obtained inorganic composite particles can be obtained without significantly reducing the pore volume inherent in the porous inorganic particles. Can be increased. Such a particle structure is proposed for the first time by the present invention, and greatly expands the use of porous inorganic particles composed of an aggregate of plate-like crystals, which has conventionally had a small pore volume and limited its use. It is.

In the present invention, the inorganic fine particles constituting the inorganic composite particles are not limited as long as the primary particle diameter is 50 to 5000 angstroms.
In consideration of the fixing power to the porous inorganic particles, those having a large amount of functional groups, particularly hydroxyl groups, on the surface are preferable. Examples of suitable inorganic fine particles include silica, alumina, titania and the like. Among them, silica is particularly preferred. The state of aggregation of the inorganic fine particles and the size of the primary particles can be confirmed by a scanning electron microscope.

[0010] The mode of fixing the aggregate of the inorganic fine particles to the porous inorganic particles is not particularly limited as long as the inorganic fine particles limit the pores of the porous inorganic particles. Specifically, it is preferable that the aggregate of the inorganic fine particles is fixed to the periphery of the pores of the porous inorganic particles or to the inside of the pores. Such a fixed state can be observed by a scanning electron micrograph. The fixing power of the aggregate of the inorganic fine particles is preferably such that 70% or more, preferably 90% or more of the inorganic fine particles remain after being treated with 50 W ultrasonic waves in water for 3 minutes. That is, when the proportion of the remaining inorganic fine particles is smaller than the above range, the fine pore diameter is significantly reduced, and in addition, the inorganic fine particles may be separated, which may cause a problem in the field of use. For example, when such an inorganic composite powder is used as a filler for paper, detachment of inorganic fine particles may cause an increase in slurry viscosity. The inorganic composite particles of the present invention in which the residual ratio of the inorganic fine particles is in the above range, for example, when the porous inorganic particles are basic magnesium carbonate, the viscosity of 25 g / 100 cc-water is generally 10 c.
Indicates a value of ps or less.

In the present invention, the ratio of the inorganic fine particles to the porous inorganic particles is 0.5 to 50 parts by weight, preferably 1 to 40 parts by weight, based on 100 parts by weight of the porous inorganic particles. preferable. When the proportion of the inorganic fine particles is less than 0.5 parts by weight, the effect of increasing the micropores of the obtained inorganic composite particles is poor. Conversely, when the proportion is more than 50 parts by weight, the obtained inorganic composite particles Not only does the effect of increasing the fine pore diameter reach a plateau, but also the inorganic fine particles are easily released, and the operation becomes difficult in production due to the thickening effect of the inorganic fine particles.

The inorganic composite particles of the present invention maintain the original pore volume of the porous inorganic particles serving as the basic skeleton,
In particular, it has the feature that the volume of pores having a diameter of 200 Å or less is large. Diameter 2 of inorganic composite particles of the present invention
The volume of the pores of not more than 00 Å depends on the type of the porous inorganic particles. For example, when the porous inorganic particles are basic magnesium carbonate, the inorganic composite particles in which the inorganic fine particles are fixed in the above range have a pore volume of 200 angstrom or less in diameter of 2 cc / 100 g or more, and a diameter of 2000 angstrom. The following pores having a volume of 10 cc / 100 g or more are suitable. Further, the pore volume of the inorganic composite particles having a diameter of 20 μm or less is preferably 50 to 150 cc / 100 g. In addition, the above pore volume is a value obtained from a value measured by a mercury porosimeter.

The method for producing the inorganic composite particles of the present invention is not particularly limited. To illustrate a typical method, for example, porous inorganic particles composed of an aggregate of plate-like crystals and a primary particle diameter of 50 to 50
A method for producing inorganic composite particles, which comprises mixing inorganic fine particles of 00 Å in a polar solvent and then drying the particles.

As the porous inorganic particles used in the above-mentioned production method, the above-mentioned known inorganic particles composed of an aggregate of plate-like crystals are used without any particular limitation.
Particles of １００100 μm, preferably 3-50 μm, are suitable. Further, in order to obtain inorganic composite particles having a large pore volume of 200 Å or less in diameter by fixing the inorganic fine particles, the pore volume of 20 μm or less is reduced to 50 cc / 1.
The volume of pores having a diameter of 200 g or more and a diameter of 200 Å or less is preferably 0.5 cc / 100 g or more,
It is preferable to use porous inorganic particles of 1 cc / 100 g or more.

The method for producing porous inorganic particles having a pore volume of 200 Å or less and a volume of 0.5 cc / 100 g or more is not particularly limited. For example, a preferred production method for the basic magnesium carbonate is as follows. It can be obtained by reacting a water-soluble magnesium salt and a water-soluble carbonate at a temperature of 40 ° C. or higher and lower than the boiling point while controlling the reaction rate, and allowing the mixture to stand and ripen in the above temperature range. Known water-soluble magnesium salts and water-soluble carbonates can be used without particular limitation. Further, the reaction rate is controlled at the reaction temperature when both are supplied as aqueous solutions, with respect to 1 mol of the salt present in one aqueous solution, the other aqueous solution is added in an amount of 0.03 to 0.5 mol / min. A method of adjusting the amount of salt to be added and adding one of the salts to an aqueous solution,
A method in which the other salt is supplied as a solid into the aqueous solution, a method in which both are supplied as solid in water, and the like can be mentioned. In addition, the standing time after the above reaction is suitably 10 minutes or more, preferably 2 hours or more.

The basic magnesium carbonate thus obtained is generally spherical and has the above-mentioned pores (hereinafter referred to as “basic magnesium carbonate”).
The basic magnesium carbonate is also referred to as spherical basic magnesium carbonate).

In the present invention, the above-mentioned types of inorganic fine particles are used without any particular limitation. The particle diameter of the inorganic fine particles is not particularly limited as long as the primary particle diameter (diameter) is smaller than the pore diameter of the porous inorganic particles within the range of 50 to 5000 Å. Those having a particle diameter that easily forms an aggregate by mixing in the medium, specifically, a primary particle diameter of 50 to 1000 angstroms are preferable.

In the present invention, the inorganic composite particles are obtained by mixing the porous inorganic particles and the inorganic fine particles in a polar solvent and then drying. That is, by the above-described means, an inorganic composite particle in which an aggregate of inorganic fine particles is fixed in and around the pore is obtained. Although the fixing mechanism of the inorganic fine particles is not clear, the inorganic fine particles dispersed by mixing in the polar solvent are aggregated in or around the pores of the porous inorganic particles, and in this state, the porous By drying while the inorganic fine particles are adhered to the inorganic particles, the aggregates of the inorganic fine particles are formed in the pores of the porous inorganic particles or in the vicinity of the pores due to dehydration condensation of hydroxyl groups present on the surfaces of the inorganic particles. It is thought that it is fixed to.

In the above method, the polar solvent includes
Examples thereof include water, alcohol, and a mixed solvent of water and alcohol. Among them, water or a mixed solvent of water and alcohol is most preferred. Further, it is preferable that the inorganic fine particles are sufficiently dispersed in a polar solvent and mixed with the porous inorganic particles in order to increase the fixing force of the inorganic fine particles and effectively form the fine pores. For example, when silica is used as the inorganic fine particles, by using dry silica having a small amount of silanol groups on the surface as a raw material, the dry silica is mixed with the porous inorganic particles into the polar solvent immediately after the supply of the silica to the polar solvent. Since the number of groups is small, it is easy to be taken into the pores of the porous inorganic particles, and after being taken in, the silanol groups increase and aggregation can be efficiently caused.

The concentration of the porous inorganic particles and the inorganic fine particles in the polar solvent is not particularly limited, but it is generally preferable to adjust the ratio of the porous inorganic particles to the inorganic fine particles in the obtained inorganic composite particles. . Also,
The concentration in the polar solvent is generally from 10 to 40
g / 100 cc is preferably adjusted.
Further, the mixing ratio of the porous inorganic particles and the inorganic fine particles depends on the composition of the target inorganic composite particles, that is, the porous inorganic particles 1
With respect to 00 parts by weight, 0.5 to 50 parts by weight of inorganic fine particles,
Preferably, a ratio of 1 to 40 parts by weight is suitable.

After the mixing, the method for drying the composite particles is not particularly limited. For example, drying methods such as standing drying and flash drying can be used.

As another method for producing the inorganic composite particles of the present invention, a porous inorganic particle and an inorganic fine particle smaller than the pore diameter of the porous inorganic particle are mixed to reduce mechanical frictional force and mechanical shearing force. A method for producing inorganic composite particles, characterized in that amorphous inorganic particles are fixed in the pores of the porous inorganic particles by adding the particles to the surface of the particles.

In the above method, the method of applying the mechanical frictional force and the mechanical shearing force to the particle surface is not particularly limited. The method of operating the airflow pulverizer is preferable. In such a method, it is presumed that the aggregate of the inorganic fine particles is fixed mechanochemically around or inside the pores of the porous inorganic particles.

[0024]

[Effect] The inorganic composite particles of the present invention have the same pore volume as the total pore volume that the porous inorganic particles originally have,
The volume of micropores having a diameter of 200 Å or less, particularly 2000 Å or less, is much larger than that of the porous inorganic particles. That is, a surprising increase effect of 1.5 times or more, and in some cases, 2 times or more, of the theoretical pore volume obtained from the volumes of the fine pores of the porous inorganic particles and the inorganic fine particles is exhibited. Therefore,
The purpose of the present invention is to dramatically expand the use of the porous inorganic particles, the use of which has been conventionally limited due to the shortage of the fine pore volume.

Since the inorganic composite particles of the present invention have a very large volume of micropores, they are required to have a liquid absorbing speed or a supporting force, specifically, a filler for filling in paper, a thermal paper, and the like. It is suitably used for applications such as fillers for paper coating materials and cosmetics.

The inorganic composite particles of the present invention have a large specific surface area. That is, the specific surface area exceeds the theoretical pore volume obtained from the specific surface areas of the porous inorganic particles and the inorganic fine particles. This results in an increase in the surface activity of the particles, and exerts a more favorable effect in the above-mentioned application.

[0027]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples. In the examples and comparative examples, the following measurements and tests were performed by the following methods.

Pore volume Porosimeter 2000 (trade name: manufactured by Carlo Elba Instruments Inc .: based on Hg)

Fixing force of inorganic fine particles 50 g of water was added to 3 g of the powder, and 3 g of ultrasonic waves (50 W) were applied.
Disperse for a minute. Three minutes later, 10 ml of the supernatant was sampled, and the ratio (% by weight) of the detached inorganic fine particles was determined.

Fixed state of inorganic fine particles Observed using a scanning electron microscope (JSM-5400 manufactured by JEOL Ltd.).

Oil Absorption Rate The powder sample 1 is introduced up to the upper surface of the container 4 having a diameter of 70 mm and a height of 40 mm and having an open upper surface. Next, a watch glass having a diameter of 65 mm and a total weight of 100 g is placed on the sample, lowered by its own weight to compress the sample, and after 15 seconds, pulled up by a string attached around the watch glass. Then, 0.2 ml of boil oil 8 was dropped on the surface of the compressed sample, and the time required from when the sample was brought into contact with the boil oil to when all the boil oil was absorbed into the sample was measured.

The particle size was measured using a Coulter Multisizer (50 μm aperture).

The primary particle size was measured using a scanning electron microscope (JSM-5400 manufactured by JEOL Ltd.).

Bleeding test of ink A black ink for a commercial printer was placed on a coated layer of coated paper at intervals of 10 drops from a glass capillar.
Two minutes after the drop, the average of the maximum diameter of the circle formed by the ink and the average of the maximum length of the beard generated by the bleeding of the ink were shown. .

The coated paper is made of the inorganic composite powder 20 of the sample.
A bar coater was used in which a coating solution consisting of 80 parts by weight of a 0.2% aqueous solution of sodium polyacrylate as a dispersant and 40 parts by weight of a 10% aqueous solution of polyvinyl alcohol as a binder was applied so that the coating amount of solids was 20 g / m ^2. By coating a commercially available high-quality paper with a known method, followed by drying.

Slurry viscosity The viscosity (cps) of 25 g / 100 cc-water of the inorganic composite particles was measured.

Examples 1 to 3 Sodium carbonate and magnesium chloride were added in equimolar amounts to water at 80 ° C. with stirring. After 60 seconds from the start of the addition, the stirring was stopped, and the mixture was allowed to stand for 1 hour while maintaining the same temperature. Next, the precipitate was filtered, washed, and dried to obtain spherical basic magnesium carbonate having an average particle size of 6.2 μm. FIG. 2 shows a micrograph showing the structure of the obtained particles of basic magnesium carbonate. As the spherical basic magnesium carbonate and the inorganic fine particles obtained by the above reaction, Leolosil QS-102 (trade name: manufactured by Tokuyama Soda Co., Ltd.) having an average primary particle diameter shown in Table 1 was added according to the formulation in Table 1 for 500.
After dispersing in water (ml), a uniform slurry was formed and dried by spray drying to obtain basic magnesium carbonate (inorganic composite particles) having dry silica fixed in the pores. As a result of observing the obtained inorganic composite particles with a scanning electron microscope and an X-ray microanalyzer, it was confirmed that the inorganic fine particles were fixed on the surface of the porous inorganic particles or in the pores. Table 2 shows various test results on the obtained inorganic composite particles. FIG. 1 shows a micrograph showing the structure of the inorganic composite particles obtained in Example 1.

Example 4 Inorganic composite particles were produced in the same manner as in Example 1 except that the synthetic silica (15 m ² / g) shown in Table 1 was used as the inorganic fine particles at the compounding ratio shown in Table 1. Table 2 shows the results of various tests on the obtained inorganic composite particles.

Example 5 In Example 1, fumed titania (trade name: Titanium Dioxide) shown in Table 1 was used as inorganic fine particles.
eP-25, 50 m ² / g: manufactured by Nippon Aerosil Co., Ltd.), except that inorganic composite particles were obtained.
As a result of observing the obtained inorganic composite particles with a scanning electron microscope and an X-ray microanalyzer, it was confirmed that the inorganic fine particles were fixed on the surface of the porous inorganic particles or in the pores. Table 2 shows various test results on the obtained inorganic composite particles.

Example 6 Example 1 was the same as Example 1 except that the porous inorganic particles were changed to Florite (calcium silicate: trade name, manufactured by Tokuyama Soda Co., Ltd.) as shown in Table 1. Similarly, inorganic composite composite particles were produced. As a result of observing the obtained inorganic composite particles with a scanning electron microscope and an X-ray microanalyzer, it was confirmed that the inorganic fine particles were fixed on the surface of the porous inorganic particles or in the pores. Also,
Table 2 shows the results of various tests on the obtained inorganic composite particles.

Comparative Examples 1 and 2 As shown in Table 2, the porous inorganic particles used in Examples 1 and 6 were individually slurried and then dried with a spray dryer to obtain particles. Table 1 shows the results of various tests on the obtained particles.

Comparative Example 3 Carbon dioxide gas was blown into the suspension of basic magnesium carbonate while adding the suspension of magnesium hydroxide and calcium hydroxide to fill the pores of the basic magnesium carbonate with calcium carbonate. Composite particles were produced. Table 2 shows the results of various tests on the obtained composite particles.

[0043]

[Table 1]

[0044]

[Table 2]

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing the structure of the inorganic composite particles obtained in Example 1.

FIG. 2 is an electron micrograph showing the structure of the inorganic composite particles obtained in Comparative Example 1.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI C09C 3/06 C09C 3/06 D21H 19/38 D21H 1/22 B (58) Fields surveyed (Int.Cl. ⁷ , DB name) ) B01J 19/00 C01B 33/24 C01F 5/24 C08K 7/16 C08K 9/02 C09C 3/06

Claims (2)

(57) [Claims] 1. A porous inorganic particle composed of an aggregate of plate-like crystals, and an aggregate of inorganic fine particles having a primary particle diameter of 50 to 5,000 angstroms with respect to 100 parts by weight of the porous inorganic particle, 0.5 to 50 wt. Inorganic composite particles with fixed parts. 2. An inorganic composite, comprising mixing porous inorganic particles composed of an aggregate of plate-like crystals and inorganic fine particles having a primary particle diameter of 50 to 5000 angstroms in a polar solvent, and drying the particles. Method for producing particles.