JPH0217932A - Modified inorganic particle and preparation thereof - Google Patents

Abstract

PURPOSE:To improve the dispersibility and stability of an inorg. particle and to enhance the adaptability thereof in various hydrophobicity utilizing fields by coating the surface of the inorg. particle with organosilicic acid represented by a specific general formula to form a modified inorg. particle. CONSTITUTION:An water-soluble alkali salt of organosilicic acid represented by formula RSiO1.5-n/2(OH)n (wherein n is 0<=n<=1 and R is a 1-4C alkyl group, a 2-4C alkenyl group or a phenyl group) is subjected to cation exchange to prepare an active organosilicic acid solution substantially containing no alkali component. Subsequently, this active organosilicic acid solution and an inorg. particle are mixed under a condition of pH-11 to obtain a modified inorg. particle coated with the organosilicic acid represented by the aforementioned formula. As the inorg. particle, substantially spherical silica is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to modified inorganic particles coated with organic silicic acid and a method for producing the same.

Furthermore, fillers for plastics, light diffusing agents, solid WJWI agents, additives for various polymers, antifoaming agents, cosmetics,
The present invention relates to the above-mentioned inorganic particles, which are suitable materials for hydrophobic fields such as ink, grease, and paint, and for ceramic fields that require fine powders due to their sinterability and optical properties.

<Conventional technology> Conventionally, R81Cj has been used to make inorganic surfaces hydrophobic depending on the purpose.
, RSi (OCH3>3 (R is various organic functional groups) and other silane materials have been fully used in water-organic gold solvent systems or organic solvent systems.
In the case of fine particles smaller than μ, it is difficult to recover the particles following hydrophobization treatment in a slurry system, and special techniques are required. That is, it is impossible to take out the fine particles formed by reaction in the aqueous phase and turn them into a solid powder using the usual steps of filtration, drying, and pulverization. Therefore, we developed a pigment manufacturing method in which the particle surface is made hydrophobic by a flushing method using a surfactant, transferred to an organic solvent, and then powdered (Color Material 55 [5] 300-304 1982), and treated with alcohol and critical temperature using an autoclave. Silica surface esterification method (υ5P265
7.149> etc. are being carried out.

<Problem to be solved by the invention> However, when R81Cj3 is used, there is a problem of Cj as an impurity, and when R81(OCH3)3 is used, an organic solvent must be handled in the flushing method, and the esterification method. It comes with complexity. In addition, the coating method using aqueous colloid adsorption has the disadvantage that the coating has a weak bonding force, is easily peeled off, and lacks durability.

Therefore, the present inventor conducted intensive research to solve the above problems, and as a result, the present invention was discovered.

Means for Solving the Problems> That is, the present invention provides a compound having the general formula RSi 01.5-n/2 (OH) on the surface of an inorganic particle. (In the formula, O≦n≦1.R represents an alkyl group of 01 to 4, an alkenyl group of C2 to 4, or a phenyl group). It is.

Inorganic particles (“core material” under JX) that serve as raw materials related to the present invention
) is preferably substantially insoluble in an alkali having a pH of 7 to 11. Further, it is desirable that the surface of the core material has an affinity for organic silicate particles. In addition, surfaces that do not have affinity may be modified to have affinity by appropriate pretreatment. The chemical composition of the core material is not particularly limited as long as it satisfies these conditions.

For example, Si, MO, Ca, zn, Cu.

Oxides such as AI, Fe, Cr, Tie Zr, silicon salts, nitrides, carbides or hydrates thereof, carbonates such as MCJ, Ca, sulfates, sulfides such as Zn, Ca, etc. Examples include phosphorus.

Although surfactants are generally used to modify the affinity surface, aluminum or chromium salts of acetic acid or formic acid, or basic salts thereof can also be used.

Further, the shape of the core material may be spherical, plate-like, needle-like, or S-shaped. Furthermore, the core material has an average particle size of 0.05
~20μ is common.

If the average particle size of the core material is within the above range, the average particle size is 0.05, which is optimal as a material for fillers for plastics, etc.
This is because modified inorganic particles of ~20μ can be obtained.

In addition, the organic silicate film represented by the general formula R8101,5-o72(OH) (in the formula, O≦n≦1.R represents a C1-4 alkyl group, a C2-4 alkenyl group, or a phenyl group) Its nature is high purity, and in most cases the content of impurities, mainly alkali, excluding ignition loss, is 0.1% by weight or less.

Further, it is preferable that the modified inorganic particles coated with organic silicic acid are substantially spherical because, as mentioned above, they are optimal as materials for fillers for plastics and the like.

Furthermore, since the modified inorganic particles have organic groups on their surfaces, they are compatible with organic substances and have good dispersibility in plastics and the like.

Further, the amount of organic silicic acid to be coated on the modified inorganic particles of the present invention is determined depending on the purpose of coating and the type of R group of the organic silicic acid used, but the amount is 1X10' to I with respect to the total surface area of the inorganic particles. It is in the range of X 10-3 mol/-. For example, in the case of methyl silicic acid, coating with a monomolecular layer is sufficient to impart hydrophobicity to a core material of 1 to 20μ, for example, 0.5X10' to 1.5X1.
A value of about 0' mol/m is sufficient.

For core materials with an rRa of 0.05 to 1μ, a coating of one or more molecular layers, preferably three or more molecular layers, is required.
For example, 1.0X10' to 1. OX10' no
t/rIL is appropriate.

Of course, the above describes the minimum amount of suspension, and there is no problem even if the amount of coating is more than 1°.As will be described later, the organic silicic acid for the core material is coated with active fine particles, Forms a very stable film.

In many cases, the core material is coated with a substantially continuous coating.

Therefore, it is possible to modify the inherent physical properties of the core material. For example, it is possible to change hydrophilicity to hydrophobicity, but it also has a shielding effect against external stimuli, making the core material physicochemically stable. can be given gender.

Next, a method for producing modified inorganic particles of the present invention will be described.

The above-mentioned modified inorganic particles can be manufactured by the following steps.

That is, general formula RS　i　O7,5-,12(OH).

(In the formula, '%l'< has the same meaning as above) A step of cation-exchanging a water-soluble alkali salt of an organic silicic acid represented by the following formula to prepare a solution of an active organic silicic acid that does not substantially contain an alkali component. This is a method for producing modified inorganic particles, which is characterized by comprising a step of mixing the solution and inorganic particles at a pH of 7 to 11.

The alkaline aqueous solution of organic silicic acid according to the present invention is not particularly limited, and can be prepared, for example, by the manufacturing method described in JP-A-55-139391, the manufacturing method described in US Pat. No. 2,438,055, US P 2, An aqueous alkali salt of organic silicic acid obtained by the method described in No. 587,636 can be used.

As the alkali in the alkaline solution of organic silicic acid, alkali metal hydroxides such as NaNKSLi, quaternary ammonium hydroxides, amines, etc. can be used.
NaOH is cheap and easy to use.

The solution of the water-soluble alkali salt of organic silicic acid is preferably a dilute solution, and its concentration varies depending on the type of R, but is from 0.1 to
A range of 1.0H/1 is appropriate.

The mountain range is 0. If it is less than IN/j, the solid content 11a is too low and is not economical, and if it exceeds 1.014/j, gelation will occur during ion exchange, which is undesirable.

The solution thus prepared is brought into contact with a cation exchange resin that has been previously converted into H+ form to remove alkali ions. Then, if necessary, impure anions in the raw material may be removed by contacting with an anion exchange resin in the OH-type.

As is clear from the above, the active organic silicic acid solution in the present invention has the general formula R81O1,5-o/2 (
OH) (where n and R have the same meaning) means a low polymerization aqueous solution of an active organic silicic acid containing many silanol groups or an acidic solution of low polymerization fine colloidal particles.

Next, the active organic silicic acid solution prepared by the above method and inorganic particles are mixed to have a pH of 7 to 11.

This active organosilicic acid has a pl-12 to 3, and this pH
It is the most stable in the range, and rapidly polymerizes at pH 7 or higher. Therefore, what is important is that the initial mixing with the core material should be on the acidic side, especially p)-12 to 3, to sufficiently homogenize the two to prevent substantial polymerization1, and then on the alkali side. It is desirable to deposit fine organic silicic acid particles, which are grown by gentle polymerization at pH 7 to 11 using an agent, on the surface of the core material particles.

The mixing method is not particularly limited as long as the above conditions are set, but some methods B can be mentioned. For example, there is a method in which inorganic particles are added to an active organic silicic acid solution, sufficiently dispersed, and then the pH is adjusted to 7 to 11 with an alkaline agent.

As the alkali agent, ammonia, caustic alkali, alkali carbonate, alkali silicate, ethanolamine, etc. can be used, and although there is no particular limitation, ammonia is often advantageous.

However, sodium aluminate, sodium silicate, etc. are not preferred because they cause particle nucleus photogenesis and produce colloids with a particle size of 1 to 20 rrμ. An aqueous solution of methyl siliconate before ion exchange is also undesirable because it causes the generation of particle nuclei.

Another method is to add a solution of active organic silicic acid to the slurry of Maga particles.

In this method, a necessary amount of alkaline agent is added in advance to the slurry of R-free particles to adjust the pH to 7 to 11, and then organic silicic acid is added.
The number of alkaline agents may be determined in advance so that the amount of the alkaline agent is 1.

Still another method is to simultaneously add an active organic silicic acid and an alkaline agent to a slurry of inorganic particles of pt-17 to 11 so that the pH of the liquid during mixing is always maintained at 7 to 11. be.

In any of the above methods, the formation of fine particles by polymerization at pH 7 to 11 must be as gentle as possible, and it is desirable to carry out the mixing gradually.

When preparing a slurry of inorganic particles, it is necessary to disperse the slurry as well as possible and prepare it in a freshly deagglomerated state so that each particle is coated with organic silicic acid. Therefore, we use high-speed stirring, ultrasonic dispersion, shear dispersion, etc. to ensure that the primary particles are dispersed as much as possible. It is advantageous to disperse the lubricant particles. The concentration of this slurry is often 50 to 300 g/,
11 or less is sufficient.

The above mixing is carried out under stirring for about 24 hours at a slurry temperature of 0 to 50°C.

The coating is thought to be formed by depositing active organic silicic acid on the surface of inorganic particles, either directly or by depositing fine particles grown through a polymerization reaction, but this polymerization reaction was initially carried out without any heating operation. It is preferable to carry out the reaction at room temperature and to heat the solution to 50° C. or higher in the final stage to complete the polymerization, since the reaction rate gradually slows down due to the reduction of the active organosilicic acid.

If this heating operation is added from the beginning of mixing, together with the above pH conditions, the polymerization reaction will be rapidly accelerated, resulting in gelation, which will impair the homogeneous deposited coating on the core material particles.

The thus obtained slurry of inorganic particles coated with organic silicic acid can be recovered by a conventional separation operation. In this case, a flocculant may be used if necessary.

After washing with water, it can be redispersed in water or a desired organic solvent to form a slurry, or dried to form a powder.

Incidentally, the drying may be not only static ordinary drying but also dynamic drying using a spray dryer or a rotary dryer.

<Example> 380 g of sodium hydroxide was dissolved in 4,500 g of λ1 water and added to a caustic soda solution whose temperature was adjusted to 60 to 65°C, with stirring.
320 fJ of methyltrichlorosilane having a purity of 99.5% and a boiling point of 66.1° C. was added over 5 hours to effect hydrolysis. Next, this was maintained at 80 to 85°C and stirred for 30 hours, and then 50% H2SO4 was added over about 1 hour at the same temperature to adjust the pH to 6.

The polymerized precipitated methyl silicic acid was collected by filtration and washed with deionized water 5j. Transfer the washed cake to a container and add 50 ml of water.
Add 0g, stir, add 172g NaOH and heat to 90°C.
Methyl silicic acid (CH3Sho) was dissolved by heating and the water content was adjusted by illumination.

, 5 > 11 degrees was prepared about 20% sodium methyl silicate solution.

A bond prepared by adding 180 g of water to this sodium methyl silicate solution 209, and a cation exchange resin (
The solution was allowed to flow down through a column containing Amberlite IR-1208 (manufactured by Organo) to recover 300 g of an active methyl silicate solution with a pH of 3.0.

Next, to 300 g of this activated methyl silica Ml solution were added particles with an average particle size of 0.1 from which alkaline components had been removed in advance by cation exchange.
After adding 26 g of monodispersed aqueous silica colloid (S i 02 = 30%) with a specific surface area of 3μ and a specific surface area of 22rd/9 and mixing thoroughly, the pH was adjusted to 8.9 with ammonia, and the mixture was heated for 24 hours to precipitate methyl silicic acid using silica as a core. After stirring, the reaction was completed by heating at 100°C for 10 minutes, and after cooling, it was filtered.

Coding place]! [! While the same silica colloid of Mi+ passes through the NO, 5C filter paper (Toyo Roshi), the one of the present invention can be recovered in its entirety with the filter paper.
The filterability was extremely good. Next, it was washed with water and dried to obtain a powder. This powder was dispersed into primary particles during handling and no particular grinding was required. According to the electron micrograph, particles with a particle size of 0.14 μ were within this range on 90× j×.

When this powder was dispersed in ethyl alcohol, a milky white homogeneous colloid with monodispersed particles was formed, and no agglomeration or sedimentation was observed.

Moreover, it did not disperse in water at all.

x1 11J 2 Perform the same operation as in Example 1 to prepare activated methyl silicate solution 3.
00g was prepared. Next, a monodisperse spherical aqueous silica colloid (S i
02=30%) Active methyl silicate solution 60 to 1009
After adding fJ and mixing thoroughly, adjust the pH to 9.0 with ammonia.
The mixture was stirred at room temperature for 1 hour and then heated at 80° C. for 10 minutes in order to precipitate methyl silicic acid using silica as a nucleus.

After cooling, active methyl silicic acid solution 609 was added and mixed to bring the pl to 19.0 again, and after stirring at room temperature for 1 hour, it was heated to 100°C.
The reaction was completed by heating for 10 minutes, cooled and filtered.

The same silica colloid before coating treatment is NO, 5C
However, in the case of the present invention, the entire amount could be recovered with the filter paper, and the filterability was extremely good.

Next, it was washed with water and dried at 110°C to obtain a powder. This powder was dispersed into primary particles during handling, and no particular pulverization operation was performed. Electron micrograph Figure 1 (magnification is s,
ooo times), it can be seen that monodispersity is maintained.

Further, this powder was dispersed in a milky white color in ethyl alcohol, but had no dispersibility in water.

As a result of pyrolysis of the coated powder, 460 ~
An exothermic weight loss of 0.53% was observed at 580°C, indicating that 98% of the active methyl silicic acid used was coated.

Average particle size used in Examples 1 and 2: 0.13μ and 0.2
A 6 μm monodispersed spherical aqueous silica colloid was dried in a spray dryer at an outlet temperature of 105° C. to form a powder. Figure 2 is an electron micrograph of the obtained powder (Figure 2 shows an average particle size of 0.2
According to the one with 6μ and the magnification is 1,000 times), all of them form secondary particles of 5 to 40μ, and 0
．． In order to disperse 26μ particles in alcohol, 24-hour grinding is required in a ball mill, and agglomerates were also observed in the crushed particles, and approximately 1/2 of the 0.13μ particles were It was just dispersed.

Add 185 g of XJ Kutan ethyl silicate to a mixture of ethanol 51009 and 28% ammonia water 1400 g.
C. for 2 hours to obtain a monodisperse spherical silica colloid with an average particle size of 0.3 .mu.m. Next, concentrate by ultrafiltration until the total liquid volume becomes 6007, add pure water while maintaining the full wave @ 6007, continue ultrafiltration, and reduce the ethanol concentration to 5.
% or less. Then, by decantation, 5 inches
2 concentration was 15%. Next, the same activated methyl silicic acid solution 2009 as in Example 1 was added to the solution, which had a pH of 11, to precipitate methyl silicic acid while stirring. After the addition, stirring was continued for 24 hours, and the reaction was completed by heating at 100° C. for 10 minutes, followed by cooling and filtration.

The same silica colloid before coating treatment is NO, 5C
However, in the case of the present invention, the entire amount could be recovered with the filter paper, and the filterability was extremely good.

After washing with water, it was washed with ethylene glycol and dried at 200°C to form a powder. This powder had extremely good dispersibility in ethylene glycol.

Example 4 Potassium alum [KAJ! (So) ・12H2
0] of 2 x 10-3not was dissolved in 11 of pure water,
Hydrolyzed by heating at 98°C for 6 hours, resulting in an average particle size of 058μ
spherical alumina hydrate fine particles were precipitated.

After this was allowed to stand still, the supernatant liquid was removed to make a total of 100 pieces. Next, 1.7 g of the same activated methyl silicate solution as in Example 1 was added thereto, mixed, and diluted with pi-1 with aqueous ammonia.
9.5, stirring was continued for 24 hours, and the reaction was completed by heating at 100° C. for 10 minutes.

After cooling, it was filtered, washed with water, and dried to form a powder.

This powder can be redispersed in alcohol, but without active methyl silicate treatment it will form secondary particles,
It also did not disperse in alcohol.

1U red phosphorus 1.547 with an average particle size of 20μ was hydrolyzed in 100-m water, 0.05 g of basic aluminum acetate was added, and after standing for 16 hours, the pH was adjusted to 7 with aqueous ammonia.
Furthermore, the same activated methyl silicon as in Example 1! ! ! ! 20y was added thereto, the pH was adjusted to 9.5 with aqueous ammonia, and after stirring for 24 hours, the mixture was heated at 100° C. for 10 minutes, left to cool, filtered, and dried to form a powder. This powder showed water repellency.

<Effects of the Invention> The inorganic particles coated with organic silicic acid obtained according to the present invention have excellent dispersibility and stability, so they can be used as fillers for plastics, light diffusing agents, and solid IM lubricants by selecting the type of core material. , additives for various polymers, antifoaming agents, cosmetics, inks, greases, paints, and other materials suitable for rough water applications.

Furthermore, the method of the present invention allows industrially advantageous production of modified amm powder particles.

[Brief explanation of the drawing]

FIG. 1 shows the structure of the particles obtained in Example 2, and FIG. 2 shows the structure of the particles obtained in Comparative Example 1, and is a scanning electron micrograph of each. Patent applicant Nihon Kagaku Kogyo Co., Ltd.

Claims (8)

[Claims] (1) General formula RSi_1_. ＿５
Coated with organic silicic acid represented by _-_n_/_2(OH)_n (in the formula, 0≦n≦1, R represents a C1-4 alkyl group, a C2-4 alkenyl group, or a phenyl group) Modified inorganic particles characterized by (2) The modified inorganic particles according to claim 1 are substantially spherical. (3) The modified inorganic particles according to claim 2 are substantially spherical silica. (4) General formula RSiO_1_. ＿5＿−＿n＿／＿２(
OH)_n (in the formula, 0≦n≦1, R represents a C1-4 alkyl group, a C2-4 alkenyl group, or a phenyl group)
A step of cation-exchanging a water-soluble alkali salt of an organic silicic acid represented by the formula to prepare an active organic silicic acid solution substantially free of alkali components, and then a step of mixing the solution and inorganic particles at a pH of 7 to 11. A method for producing modified inorganic particles characterized by (5) The mixing step of claim 4 is a method for producing modified inorganic particles in which inorganic particles are added and mixed into an active organic silicic acid solution. (6) The mixing step of claim 4 is a method for producing modified inorganic particles in which an active organic silicate solution is added to a slurry of inorganic particles. (7) A method for producing modified particles in which the mixing step of claim 4 is carried out by simultaneously adding an active organic silicic acid and an alkaline agent to an inorganic slurry having a pH of 7 to 11. (8) A method for producing modified inorganic particles, wherein the alkaline agent according to claim 7 is ammonia.