WO2008072637A1

WO2008072637A1 - Method for producing colloidal silica

Info

Publication number: WO2008072637A1
Application number: PCT/JP2007/073884
Authority: WO
Inventors: Taku Konishi
Original assignee: Fuso Chemical Co. Ltd.
Priority date: 2006-12-12
Filing date: 2007-12-11
Publication date: 2008-06-19
Also published as: CN101547860B; TW200831408A; JPWO2008072637A1; JP5155185B2; CN101547860A

Abstract

Disclosed is a method for producing a colloidal silica using silicon metal as a raw material, which enables to produce a colloidal silica having high concentration and low viscosity. Also disclosed a method for producing a colloidal silica using silicon metal as a raw material, which enables to produce a colloidal silica in short time with high yield without comprising a concentration step. Further disclosed is a method for producing a colloidal silica, which enables to easily control the particle size of silica contained in a colloidal silica. Specifically disclosed is a method for producing a colloidal silica comprising a step for obtaining a colloidal silica by reacting silicon metal (Si) with water in an aqueous solution containing an alkaline catalyst and a dispersing agent, wherein the dispersing agent is composed of one or more ionic substances selected from inorganic acids, organic acids and their salts. Also specifically disclosed is a method for producing a colloidal silica comprising a step for controlling the particle size of silica by adjusting the addition rate of silicon metal into an aqueous solution containing an alkaline catalyst and a dispersing agent.

Description

Specification

Method for producing colloidal silica

Technical field

[0001] The present invention relates to a method for producing a novel colloidal silica that is suitably used as a polishing agent for substrates such as silicon wafer compound semiconductors, glass, and hard disks, and more specifically, metal silicon in an aqueous solution containing an alkaline catalyst and a dispersant. The present invention relates to a method for producing a colloidal shear force including a step of reacting (Si) with water to obtain colloidal silica.

Background art

Conventionally, colloidal silica has been used as a polishing agent or anti-slip agent for metal materials. The colloidal silica can be produced by hydrolyzing and polycondensing an alkoxysilane using metal silicon as a raw material, or by neutralizing or reacting an ion exchange resin or the like with water glass in which metal silicon is alkali-dissolved. Examples thereof include a method obtained by acidification, and a method in which an aqueous solution containing an inorganic alkali monovalent metal compound, ammonia and an amine is heated, and a metal silicon powder or lump is mixed and reacted. The production methods described in Patent Documents !! to 4 include a step of obtaining silicon dioxide by reacting metal silicon with water, and colloidal silica can be obtained in one reaction step, so that the number of steps is small. Therefore, it is advantageous compared with other manufacturing methods.

[0003] Patent Document 5 includes a method for producing colloidal silica using metal silicon as a raw material, and a method for obtaining colloidal shear force at a high concentration of about 30% and a high yield of 80% or more by only the reaction step. Being! / Scheme for obtaining a silicon dioxide described in this document are as follows der dissolution reaction: Si + 2_Rei_H- + H_〇 → Si_〇 ² - + 2H † (1)

2 3 2

Polymerization reaction: Si ○ ² — + H 0 → SiO +20 H — (2)

3 2 2

Overall reaction formula: Si + 2H〇 → Si〇 + 2H † (3)

2 2 2

If the reaction proceeds completely, as shown in formula (3), colloidal silica is produced from metallic silicon in the presence of an alkaline catalyst. In this case, 2 mol of water is consumed per lmol of metallic silicon, 2 mol of hydrogen will be produced. [0004] However, this production method has a problem that the viscosity of the reaction solution increases as the concentration of the reaction solution increases in the reaction step of water and metal silicon. This increase in viscosity causes a decrease in filterability and yield in the purification step of separating the reaction solution from unreacted residues.

On the other hand, in order to improve the filterability and yield of colloidal silica, it is necessary to separately carry out the concentration step of the reaction solution to obtain a low viscosity and high concentration colloidal silica. If it takes time, I have a problem.

[0005] Patent Document 6 describes a method of increasing the concentration of colloidanol silica by adding an inorganic salt such as sodium sulfate or sodium chloride. However, although this method can obtain a certain level of high colloidal silica, it is not a method of obtaining colloidal silica by reacting metal silicon powder with an alkaline aqueous solution. That is, the production method described in Patent Document 6 is such that colloidal silica particles are formed in a predetermined size through a very complicated process, and then the inorganic salt is added and concentrated to a high concentration. That is, in the method described in Patent Document 6, the inorganic salt is not added to the reaction liquid during the reaction, and is limited after the production of silica particles, so that the production efficiency is low. If a dispersing agent is added before the formation of silica particles, not only a low-viscosity and high-concentration colloidal silica can be produced, but also the working efficiency is extremely lowered due to the increase in viscosity.

That is, in producing colloidal silica using metal silicon as a raw material, in order to provide a simple production method while minimizing the number of steps, a production method capable of producing high-concentration and low-viscosity colloidal silica without concentration. The invention has not yet been created.

[0006] Furthermore, in the production of colloidal silica to be applied to various uses, it is necessary to adjust the particle diameter of silica contained therein. For example, the silica contained in colloidal silica used for binders such as precision forging molds, ceramic smoker molding, and refractory molding preferably has a small particle size with a strong binding force. On the other hand, the silica contained in colloidal silica used for matte paint fillers, substrate abrasives, anti-slip agents for paper products and fibers, etc. should have a large particle size. Large particle size silica provides high shielding and anti-slip effects.

[0007] With regard to particle size control, the methods described in Patent Documents 1 to 4 efficiently use metallic silicon. Regarding the method of dissolving and solling, there is no mention of adjusting the particle size. For example, in Patent Document 7, the size of heel particles in the aqueous colloidal silica is increased by adding metal silicon to the water (original particles) of the aqueous colloidal silica containing ammonium hydroxide, thereby controlling the particles. A method for producing colloidal silica is described.

[0008] However, according to the invention described in Patent Document 7, the particle adjustment of colloidal silica requires a particle adjustment step after the production of colloidal silica. Have a problem!

That is, colloidal silica produced using metal silicon as a raw material is required to be a simple production method with a reduced number of steps, and to adjust the particle size of silica contained in the colloidal silica in the reaction step. However, the present situation is that such inventions have been created.

[0009] In addition, as a method for producing general-purpose colloidal silica, a so-called ion exchange method, a dilute water glass is treated with a cation exchange resin to produce a sodium free active silicate aqueous solution. A part of the particles is heat-aged to produce nuclei of silica particles, and the activated silicic acid aqueous solution is added over time to the stirring of the heated dispersion containing the nuclei. The method of making it grow in a shape is mentioned. According to this method, colloidal silica containing silica having an arbitrary particle size from small particles to large particles is produced. Finally, dilute colloidal silica having a silica concentration of 2 to 5% by weight is concentrated by evaporation or ultrafiltration. By shrinking, an aqueous colloidal silica having a silica concentration of 20 to 50% by weight is obtained (see Non-Patent Document 1).

In other words, the method for producing colloidal silica described in Non-Patent Document 1 limits the molar ratio (SiO 2 / Na 2 O) of the heated dispersion containing the nuclei of silica particles, and controls the addition rate of the silicic acid aqueous solution.

twenty two

By controlling the particle size, the particle size is controlled. As a result, although colloidal silica containing silica having a desired particle size can be obtained, it is necessary to take steps such as thermal aging and ion exchange treatment, and further a concentration operation for increasing the silica concentration. In order to obtain colloidal silica having a desired particle size, there is a problem that extra time and cost are required. Patent Document 1: U.S. Pat.No. 2,614,993

Patent Document 2: U.S. Pat.No. 2,614,994

Patent Document 3: U.S. Patent No. 2614995

Patent Document 4: Japanese Patent Publication No.49 4637

Patent Document 5: JP-A-49 64595

Patent Document 6: Japanese Patent Publication No. 37-9961

Patent Document 7: Japanese Patent Publication No. 48-13833

Non-Patent Document 1: Akiyoshi Yoshida, Chemistry and Industry, Vol. 45, No. 5, p45 (1992)

Disclosure of the invention

Problems to be solved by the invention

An object of the present invention is to produce colloidal silica having a high concentration and a low viscosity in a method for producing colloidal silica using metal silicon as a raw material.

Another object of the present invention is to provide an unreacted residue in a high yield in a short time without concentrating the colloidal silica obtained by the reaction between metal silicon and water in the method for producing colloidal silica using metal silicon as a raw material. It is intended to provide a method for producing colloidal silica, which can be purified by filtration.

Another object of the present invention is to provide a particle diameter of silica contained in colloidal silica simply and with a small number of steps in the production process of obtaining colloidal silica by reacting water and metal silicon in a reaction solution containing an alkaline aqueous solution and metallic silicon. It is intended to provide a method for producing colloidal silica containing silica from small particles to large particles. Means for solving the problem

[0011] The invention according to claim 1 is characterized in that metallic silicon is used in an aqueous solution containing an alkaline catalyst and a dispersant.

A step of obtaining colloidal silica by reacting (Si) with water, wherein the dispersant is one or more ionic substances selected from inorganic acids, organic acids or salts thereof. The present invention relates to a force manufacturing method.

The invention according to claim 2 is characterized in that the dispersant is one or more inorganic acids selected from hydrochloric acid, nitric acid or sulfuric acid and / or a salt thereof. About. [0012] The invention according to claim 3 is that the dispersant is an inorganic acid salt, and the salt is selected from a salt with Na, K, Li, NH, ammine or a quaternary ammonium hydroxide. That is more

Four

The method for producing colloidal silica according to claim 2, wherein:

The invention according to claim 4 is characterized in that the dispersant is oxalic acid, citrate, malic acid, maleic acid, tartaric acid, gnoretaric acid, adipic acid, pimelic acid, succinic acid, malonic acid, fumaric acid, phthalic acid, formic acid, Acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-peptanoic acid, 2-methylhexanoic acid _N -octanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, or lactic acid, one or more organic acids selected from lactic acid and / or a salt thereof, The production of colloidal silica according to claim 1 Regarding the method.

[0013] In the invention according to claim 5, the dispersant is an organic acid salt, and the salt is Na, K, Li, NH.

, One or more selected from salts with amines or quaternary ammonium hydroxides

Four

5. The method for producing colloidal silica according to claim 4, wherein the colloidal silica is produced.

The invention according to claim 6 is a mixture of one or more metal monohydric hydroxides containing the alkaline catalytic power sodium (Na), potassium (K) or lithium (Li). The present invention relates to a method for producing colloidal silica according to any one of 1 to 5.

[0014] The invention according to claim 7, claim 1 to 6 have a kinematic viscosity after filtration is purified by a membrane filter of the colloidal silica having a pore size 1 [I m is equal to or less than 4 mm ² / s The present invention relates to a method for producing colloidal silica according to any one of the above.

The invention according to claim 8 relates to the method for producing colloidal silica according to any one of claims 1 to 7, wherein the silica concentration of the colloidal silica is 20% by weight or more.

[0015] The invention according to claim 9 relates to a method for producing colloidanol silica according to claim 1, comprising at least the following steps.

[Step 1] Prepare an aqueous solution containing water, alkaline catalyst and dispersant

[Step 2] Prepare a slurry liquid or metallic silicon in which metallic silicon is dispersed in water

[Step 3] Add the slurry liquid or metal silicon prepared in Step 2 to the aqueous solution obtained in Step 1 at a substantially constant rate, or add the slurry prepared in Step 2 to the aqueous solution obtained in Step 1. In parallel to adding the liquid or metal silicon at a substantially constant rate, the alkaline catalyst is added at a substantially constant rate.

The invention according to claim 10 is characterized in that, in the step 3, colloidal silica containing silica having a desired particle diameter is obtained by controlling the addition rate of the slurry liquid or metal silicon. It is related with the manufacturing method of the colloidal silica of description.

[0016] The invention according to claim 11 is characterized in that, as the addition rate, the addition amount of metal silicon per hour: the amount of reaction liquid per hour;! To 9.5% by weight Claim

The method for producing colloidal silica according to 9 or 10.

The invention according to claim 12 is characterized in that the particle size of the silica contained in the colloidal silica obtained in the step 3 is 6 to 80 nm as its primary particle size. The present invention relates to a method for producing colloidal silica.

[0017] The invention according to claim 13 relates to a method for producing colloidal silica comprising at least the following steps.

[Step I] Prepare an aqueous solution containing water and alkaline catalyst

[Step II] Prepare a slurry liquid or metallic silicon in which metallic silicon is dispersed in water

[Step III] Add the slurry liquid or metal silicon prepared in Step II to the aqueous solution obtained in Step I at a substantially constant rate, or add the slurry prepared in Step II to the aqueous solution obtained in Step I. In parallel with adding liquid or metallic silicon at a substantially constant rate, an alkaline catalyst is added at a substantially constant rate.

The invention according to claim 14 is to obtain colloidal silica containing silica having a desired particle size by controlling the rate of addition of a slurry-like liquid in which metallic silicon is dispersed in water or metallic silicon in the step III. 14. The method for producing colloidal silica according to claim 13, wherein the colloidal silica is produced.

The invention's effect

[0018] The method for producing colloidal silica of the present invention is a method for producing colloidal silica force using metallic silicon (Si) as a raw material, and reacts metallic silicon and water in an aqueous solution containing an alkaline catalyst and a dispersant. A reaction step of obtaining colloidal silica. The resulting colloidal silica has a high concentration and a low viscosity. Specifically, colloidal silica is used for the silica concentration. Considering the intended use, it is preferably 20% by weight or more and 50% by weight or less. Therefore, it is economical because it is not necessary to concentrate the colloidal silica after the reaction step, and since the colloidal silica has a low viscosity, it can be purified in a short time and with a high yield with good filterability. Thus, colloidal silica can be industrially produced by a method for producing colloidal silica using metal silicon as a raw material.

According to the production method of the present invention, the dispersant can be used either before or after the formation of silica particles, so that the working efficiency is high. Even if a dispersant is added before the formation of silica particles, the viscosity of the colloidal silica does not increase.

Furthermore, according to the production method of the present invention, it is a production method of colloidal silica using metal silicon (Si) as a raw material, and it is possible to adjust the particle size of silica contained in the colloidal silica in the reaction step. Therefore, since the particle size adjusting step is not included after the colloidal silica is formed, the force S can be easily used to manufacture colloidal silica containing silica having a desired particle size in a small number of steps.

BEST MODE FOR CARRYING OUT THE INVENTION

[0019] The method for producing colloidal silica of the present invention includes a step of obtaining colloidal silica by reacting metal silicon (Si) with water in an aqueous solution containing at least an alkaline catalyst and a dispersant. Hereinafter, the manufacturing method of the colloidal silica of this invention is demonstrated in detail.

[0020] The colloidal silica according to the present invention is preferably produced by the following four process forces.

(1) Metal silicon graining process (hereinafter sometimes simply referred to as process (1))

(2) Metal silicon inactive treatment process (hereinafter, simply referred to as process (2))

(3) Metal silicon and water reaction process (Hereafter, it may be simply referred to as process (3))

(4) Filtration purification process of colloidal silica (hereinafter sometimes simply referred to as process (4))

[0021] The step (1) is a step of forming metal silicon as a raw material into particles.

The metal silicon used as a raw material is not particularly limited, and an alloy may be used. However, since the metal silicon used directly affects the purity of the colloidal silica produced, it is preferable to use high-purity metal silicon.

The method for forming metal silicon particles in the step (1) is not particularly limited, but a method of pulverizing metal silicon is preferable. In this step, preferably the particle size is 2-40 111 Is done. The reason for this is that if the length is less than 2 m, a great amount of labor and cost are required for grinding, whereas if it exceeds 40 111, the reaction tends to hardly proceed.

[0022] The step (2) is a step of inactivating the metal particles obtained in the step (1).

Metallic silicon that has been pulverized in step (1), especially metal silicon immediately after pulverization, is deactivated to metallic silicon before step (3) because its surface activity is too high if used as it is. It is desirable to perform processing. Examples of the inactivation treatment include surface oxidation treatment using an oxidizing gas or the like.

Next, the reaction step of metal silicon and water in step (3) will be described. In the method for producing colloidal silica of the present invention, this step (3) is an essential step included in the method for producing colloidal silica of the present invention.

In the step (3), colloidal silica is obtained by reacting metal silicon with water in an aqueous solution containing an alkaline catalyst and a dispersant. The water, alkaline catalyst, and dispersant that are preferably used in the step (3) are as follows.

[0024] As the metallic silicon used in the step (3), metallic silicon particles subjected to the step (1) and the step (2) are preferably used.

The water used in step (3) may be ultrapure water, but tap water, natural water, industrial water, recovered water and the like containing a large amount of ionic impurities are also preferably used.

The alkaline catalyst used in step (3) is not particularly limited, but a basic metal-valent hydroxide is preferably used. Specifically, sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide or rubidium hydroxide can be used, and these may be used alone or in combination. In particular, it is preferable to use a strong base such as a metal hydroxide such as sodium hydroxide, potassium hydroxide or lithium hydroxide. Most preferably, sodium hydroxide is used. This is because these metal hydroxides are excellent in solubility of metal silicon.

[0025] The dispersant used in the step (3) is not particularly limited as long as it is an ionic substance selected from an inorganic acid, an inorganic acid salt, an organic acid, and an organic acid salt. Preferably, this ionic substance is used. Can reduce the viscosity of colloidal silica using water as a dispersion medium. The dispersants according to the present invention may be used alone or in combination of two or more. However, colloidal silica Aggregation occurs when the pH of the colloidal silica is 7 or less. Therefore, it is preferable to add colloidal silica so that the pH of the colloidal silica is 7 or less! /.

Inorganic acids include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, alkyl phosphoric acid ester, boric acid, pyrophosphoric acid, borofluoric acid, tetrafluoroboric acid, hexafluorophosphoric acid, and benzene Examples thereof include sulfonic acid and naphthalenesulfonic acid, among which hydrochloric acid, nitric acid and sulfuric acid are preferably used.

Organic acids include citrate, oxalate, malic acid, maleic acid, tartaric acid, tartaric acid, adipic acid, pimelic acid, succinic acid, malonic acid, fumaric acid, phthalic acid, formic acid, acetic acid, propionic acid, butyric acid , Valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-Ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid and lactic acid.

The salt of the inorganic acid and organic acid is preferably Na, K, Li, NH, ammine, quaternary.

Four

Examples thereof include salts with high-grade ammonium hydroxide.

Preferred inorganic acid salts include inorganic ammonium salts such as ammonium sulfate, ammonium hydrochloride, ammonium nitrate, monoammonium phosphate, diammonium hydrogen phosphate, and ammonium borate octahydrate. Organic acid salts include the organic ammonium salts, ammonium benzoate, ammonium citrate, ammonium citrate, ammonium oxalate, ammonium formate, ammonium formate, ammonium salicinoleate, ammonium adipate, acetic acid Ammonium and tetramethylammonium taenoate.

Among the dispersants, the most preferably used dispersant is triammonium citrate, sodium sulfate, ammonium nitrate and / or sodium chloride.

The dispersant according to the present invention has an advantage that a more effective substance can be freely selected from an inorganic acid, an organic acid or a salt thereof in consideration of the use of colloidal silica.

[0027] In the step (3), the temperature of the reaction solution for reacting metal silicon and water in an aqueous solution containing an alkaline catalyst and a dispersant is preferably relatively high. This is because the higher the temperature, the higher the yield of colloidal silica. Specifically, the temperature of the reaction solution is Preferably, it is adjusted to a range of 60 to 90 ° C. As used herein, the term “reaction liquid” refers to an aqueous solution obtained by further reacting metal silicon with water in an aqueous solution containing an alkaline catalyst and a dispersant. Uh.

[0028] The addition amount of the alkaline catalyst in the step (3) is set as follows. In the production method of the present invention, when sodium hydroxide is used as the alkaline catalyst, the molar ratio of the total amount of metal silicon and sodium hydroxide: Si / NaOH (mol ratio) is preferably between 10 and 100. . In order to achieve this molar ratio, for example, when 30% by weight of colloidal silica is prepared, sodium hydroxide may be included in the reaction solution in an amount of 0.15 to 1.7% by weight. preferable. When other metal hydroxides are used as alkaline catalysts, it is desirable to add an amount equivalent to the chemical equivalent in order to maintain reactivity.

The concentration of sodium hydroxide in the reaction solution is preferably kept constant to some extent by adding sodium hydroxide to the reaction solution during the reaction. In order to improve the reaction rate of step (3) and the solubility of metallic silicon and to always obtain a constant yield, the alkaline catalyst is preferably divided addition in which the catalyst is added during the reaction.

[0029] The amount of the dispersant added in step (3) is not particularly limited, but is within the range of 0.;! To 2.5% by weight with respect to the total amount of metal silicon used. The reason for this is that even if added in excess of 2.5% by weight, no further dispersing effect is observed, and if it is less than 0.1% by weight, the effect as a dispersing agent cannot be expected, which is preferable in any case. Because there is no. In addition, the dispersant in the reaction step (3) may be added at the beginning, middle or end of the reaction step, or may be added in multiple portions. Preferably, it is added before and / or during the reaction. For example, when no increase in viscosity is observed during the reaction process, it may be added after the reaction is completed and colloidal silica is produced.

[0030] In step (3), preferably, the following procedure A or procedure B is employed.

(Procedure A)

[Step 1] Prepare an aqueous solution containing water, alkaline catalyst and dispersant.

[Step 2] Disperse metallic silicon in water to prepare slurry liquid or metallic silicon.

[0031] In steps 1 and 2, V may be shifted first. In Step 2, the metal silicon is dispersed in water in advance to form a slurry, and then added to an aqueous solution containing an alkaline catalyst, so that the rapid reaction that occurs when the metal silicon and the alkaline catalyst react directly in contact with each other. Heat generation and foaming can be prevented.

[0032] In Step 3, the slurry-like solution or metal silicon prepared in Step 2 is added to the aqueous solution in Step 1, and the rate of addition is substantially constant using a metering pump or the like. It is preferable to keep.

[0033] As described above, in order to realize the content of the alkaline catalyst in the reaction solution, the concentration of the alkaline catalyst in the aqueous solution prepared in Step 1 is preferably 0.05 to 4.0% by weight. In particular, sodium hydroxide has a concentration of 0.;! To 2.0% by weight, and in the case of other metal hydroxides, it is desirable that the concentration be comparable to the chemical equivalent and alkali strength.

[0034] In Step 3, the slurry solution or metal silicon prepared in Step 2 is added to the aqueous solution obtained in Step 1 at a substantially constant rate to prepare a reaction solution. In this reaction solution, metal silicon and water react to produce colloidal silica.

Since it is desirable that the concentration of the alkaline catalyst in the reaction solution as described above is desired to be constant to some extent, in Step 3, the alkaline catalyst is preferably added to the reaction solution at a substantially constant rate. Specifically, in order to keep the concentration of the alkaline catalyst in the reaction solution within the range of 0.;! To 2.0% by weight in the case of sodium hydroxide, sodium hydroxide is added in parallel with the addition of metal silicon. Add. The addition of the alkaline catalyst to the reaction solution is preferably performed using a metering pump or the like.

For example, when the alkali concentration in the reaction solution suddenly increases (that is, when the addition rate of the alkaline catalyst is too high), heat is generated violently and hydrogen is generated abundantly. In addition, when the alkali concentration is lower than the above-described concentration range, the reactivity is deteriorated, which is not preferable in any case.

Next, procedure B will be described. Procedure B has the following configuration. [Step a] An aqueous solution containing water, an alkaline catalyst and a dispersant is prepared.

[Step b] Prepare a slurry liquid or metallic silicon in which metallic silicon is dispersed in water.

[Step c] Add the slurry liquid or metal silicon prepared in step b to the aqueous solution obtained in step a at a substantially constant rate, or add the slurry prepared in step b to the aqueous solution obtained in step a. In parallel with the addition of the liquid or metal silicon at a substantially constant rate, the step of adding the alkaline catalyst at a substantially constant rate is desired to control the addition rate of the slurry liquid or metal silicon. Colloidal silica containing silica with a particle size of is obtained.

[0036] The order of the steps a and b and the addition rate and amount of the alkaline catalyst added to the step c at a substantially constant rate are the same as those described in the procedure A above. Adopted suitably

Yes

[0037] The adjustment of the particle size of the silica by controlling the addition rate in step c will be described.

In other words, the difference between Procedure A and Procedure B is that in Step B of Procedure B, it is intentionally controlled by controlling the silica particle size acceleration.

[0038] Specifically, it is desirable that the addition rate is as follows: the addition amount power S of metallic silicon per hour, the reaction liquid amount per hour;! To 9.5% by weight.

For example, when the amount of metal silicon added per hour is 4.3 to 9.5% by weight of the reaction liquid amount per hour, that is, when the addition rate is relatively high, the particle size is approximately 6 to A 19 nm relatively small silica particle is formed.

On the other hand, when the addition amount of metallic silicon is 1 to 4.2% by weight of the reaction liquid amount per hour, that is, when the addition rate is relatively slow, the particle size is roughly 20 to 80 nm. Large particles. Accordingly, it is possible to obtain colloidal silica having a desired particle size by controlling the rate of addition of the slurry liquid or metal silicon to the reaction liquid.

[0039] If the addition rate is too high, hydrogen is generated remarkably and lacks in safety, and if it is too slow, the reactivity becomes worse, which is not preferable. Accordingly, it is desirable that the addition rate be 1 to 9.5% by weight of the reaction liquid amount per hour.

Specifically, when a sodium hydroxide aqueous solution is used as the alkaline aqueous solution, the amount of metal silicon added per hour is 3 to 5.7% by weight of the reaction liquid amount per hour. The power S is desirable. By controlling the particle diameter as described above, colloidal silica containing silica having a particle diameter of approximately 6 to 80 nm can be efficiently produced.

After completion of the reaction, unreacted metal silicon residue is filtered off by filtration to produce colloidal silica.

Depending on the particle size, it can be used in various applications. Especially, colloidal silica of 40 to 80 nm uses the polishing power due to the hardness of the particles. Used for finish polishing of thermal oxide film substrates and silicon wafers. In addition, colloidal silica having a particle diameter of 40 nm, preferably 30 nm or less, is highly used as a filler for improving the hardness of plastic because of its high transparency.

[0040] An aqueous solution containing water, an alkaline catalyst and a dispersing agent is prepared in steps 1 and a in steps A and B above, and metal silicon is dispersed in water in steps 2 and b. Prepared slurry-like liquid or metallic silicon is prepared. However, as a modification of the present invention, in steps 1 and a, an aqueous solution containing water and an alkaline catalyst is prepared, and in steps 2 and b, a slurry-like liquid in which a dispersant and metal silicon are dispersed in water is prepared. May be. In this case, in stages 3 and c, a slurry-like liquid containing metallic silicon and a dispersing agent is added at a substantially constant rate to an aqueous solution containing water and an alkaline catalyst. Even in this modified example, colloidal silica having a high concentration and low viscosity can be produced. In a short time without concentrating the colloidal silica, the colloidal silica can be separated from the unreacted residue by filtration in a short period of time! Can be purified.

[0041] The colloidal silica obtained in the step (3) according to the present invention has a high concentration and a low viscosity.

Therefore, it is not necessary to concentrate the colloidal silica after this step (that is, the method for producing the colloidal silica of the present invention may be a production method not including the concentration step). In addition, since this colloidal silica has a low viscosity, it can be refined in a short time with a good filterability and in a high yield. Therefore, colloidal silica is industrially produced by a method for producing colloidal silica using metal silicon as a raw material. Can be manufactured. Furthermore, since the dispersant used in step (3) may be added before or after the formation of silica particles, the working efficiency is high. That is, even if a dispersant is added before the formation of silica particles, the viscosity of colloidal silica does not increase.

Yes

[0042] In the step (3) according to the present invention, when the procedure B is adopted, in addition to the advantages described above, The particle diameter of silica can be adjusted during the reaction process of water and metallic silicon. Therefore, since the particle size adjusting step is not included after the colloidal silica is formed, colloidal silica having a desired particle size and containing sili- cal force can be easily produced with few steps. Further, since the reaction solution contains a dispersant, the produced silica has high dispersibility, and therefore, the particle size can be controlled efficiently. Furthermore, the colloidal silica produced by this procedure B has a low viscosity and a high concentration of colloidal silica, and can be freely designed with a force and a particle size of several nanometers to about lOOnm. Therefore, it can be used in a wide range of applications from fillers that require high concentration and transparency to abrasive grains that emphasize the polishing rate.

[0043] After step (3) is completed (after the addition of the slurry-like liquid or metal silicon to the reaction liquid), the reaction liquid is held for a certain period of time to promote the dissolution reaction of metal silicon, and then cooled. The The holding time for the dissolution reaction is not particularly limited, but is preferably 2 to 10 hours after hydrogen generation is stopped.

The silica concentration of the colloidal silica in the reaction solution obtained in the step (3) is preferably 20 to 50% by weight.

[0044] In the case where the aqueous solution prepared in the step 1 or a does not contain a dispersant, that is, the reaction solution contains a dispersant, in some cases! It is possible to control the particle size. This is illustrated in Examples 7-12 below. In this case, colloidal silica is produced by a production method comprising Procedure C comprising the following steps 段階 to ΠΙ. The alkaline catalyst, water, and metallic silicon used are preferably the same as those in the above-mentioned procedure Α and procedure Β.

[Step I] Prepare an aqueous solution containing water and alkaline catalyst

[Step III] Add the slurry liquid or metal silicon prepared in Step II to the aqueous solution obtained in Step I at a substantially constant rate, or add the slurry prepared in Step II to the aqueous solution obtained in Step I. In parallel with the addition of the liquid or metal silicon at a substantially constant rate, at the stage of adding the alkaline catalyst at a substantially constant rate, by controlling the addition rate of the slurry liquid or metal silicon. Colloidal silica containing silica having a desired particle size is obtained. [0045] Also in this procedure C, as described in the explanation of procedure B, the addition rate of metal silicon per hour is 1 to 9.5 wt% of the reaction liquid amount per hour. It is desirable that the weight be

On the other hand, when the addition amount of metallic silicon is 1 to 4.2% by weight of the reaction liquid amount per hour, that is, when the addition rate is relatively slow, the particle size is roughly 20 to 80 nm. Large particles. Therefore, it is possible to obtain colloidal silica having a desired particle diameter of preferably 6 to 80 nm by controlling the rate of addition of the slurry liquid or metal silicon to the reaction liquid.

Next, step (4) will be described.

If necessary, the reaction solution obtained in step (3) may be filtered to separate it from unreacted residues to purify colloidal silica (step (4)).

The filtration method is not particularly limited, and examples thereof include filter filtration, vacuum filtration, and pressure filtration. Specifically, the method of reducing the pressure and separating the cake residue is preferable not only because the work is easy, but also in order to increase the yield of colloidal silica.

The yield of colloidal silica obtained in the filtration and purification step of this step (4) is the same as that of the colloidal silica having a silica concentration of 20-50% by weight obtained in step (3) at 25 ° C with a pore size of 1 μm and a diameter of 90 mm. With a membrane filter of 0.075 mPa, the yield based on the filtration amount for 10 minutes is 60% or more, more desirably 80% or more.

The “yield” in the present specification is calculated by (the amount of generated silica mol / the amount of added metal silicon mol) × 100 (%).

[0047] The colloidal silica obtained after the step (4) preferably has an extremely high silica concentration of 30 wt% or more, more desirably 35 wt% or more. Further, the kinematic viscosity is 4 mm ² / s or less, preferably 2.73 mm ² / s or less, and the viscosity is low.

The primary particle diameter of the silica particles contained in the colloidal silica is 7 to 80 nm, preferably 10 to 40 nm, and the secondary particle diameter is 10 to 150 nm, preferably 12 to 120 nm. Colloidal silica containing silica particles of these particle sizes is low in viscosity and very stable, and is highly useful and has high commercial value.

As used herein, the primary particle size is an average particle size calculated from the specific surface area determined by the nitrogen adsorption method (BET method), and the secondary particle size is the optical scattering method (measuring instrument). The average particle size measured by ELS-8000 manufactured by Otsuka Electronics Co., Ltd.) is shown.

[0048] The colloidal silica obtained in the step (4) is used as a binder for precision fabrication, refractory, ceramic fiber, etc., as an anti-slip agent for textiles, plastics, etc. As an irritant, it is suitably used as a polishing agent for substrates such as silicon wafer compound semiconductors, glass, and hard disks, or as a catalyst, catalyst carrier, soil hardening agent, or the like.

Example

Hereinafter, the present invention will be described in more detail using examples.

[Example 1]

Metal silicon powder having an average particle size of 40 11 m was pulverized to produce metal silicon having an average particle size of 5 11 m. This metal silicon was oxidized by a drier in the atmosphere and subjected to an inert treatment.

To a Teflon-lined reaction flask equipped with a 1 L capacity stirrer and reflux apparatus, 16 5 liters of tap water, 1.33 g of sodium hydroxide (containing 97% special grade) as an alkaline catalyst, and 1.06 g of ammonium nitrate as a dispersing agent are added. While stirring, the temperature of the liquid was raised to 80 ° C, and 98.8 g of metallic silicon that had been subjected to inert treatment was dispersed in 334.8 g of tap water to form a slurry, which was then mixed with a metering pump. It was added at a constant rate over time. In parallel with this, 29.9 g of a 10% by weight aqueous sodium hydroxide solution was added at a constant rate over 4 hours using a metering pump.

The dissolution reaction was further continued for 2 hours. After cooling, the reaction mixture was filtered off from the unreacted residue by vacuum filtration at 0.075 mPa with a 1,90 diamm membrane filter. The produced colloidal silica was monodispersed particles having a concentration of 34.7% by weight, a primary particle diameter of 22 nm, and a secondary particle diameter of 33 nm, and had a kinematic viscosity of 2.73 mm ² / s. The filtration amount for 10 minutes by vacuum filtration was 214.6 g, and the yield was 81%. [0050] [Example 2]

Instead of adding ammonium nitrate as a dispersing agent, sodium chloride was added (same chemical equivalent as ammonium nitrate), and the procedure was the same as in Example 1 except that. The produced colloidal silica was monodispersed particles having a concentration of 34.34% by weight, a primary particle size of 23.46 nm, and a secondary particle size of 47.4 nm. The kinematic viscosity was 2.49 mm ² / s. In addition, the filtration amount in 10 minutes by vacuum filtration was 228.8 g, and the yield was 80%.

[0051] [Example 3]

Instead of adding ammonium nitrate as a dispersing agent, triammonium citrate was added (same chemical equivalent as ammonium nitrate), and the procedure was the same as in Example 1. The produced colloidal silica was monodispersed particles having a concentration of 31.26% by weight, a primary particle diameter of 19 nm, and a secondary particle diameter of 27.8 nm. The kinematic viscosity was 3.54 mm ² / s. Further, the filtration amount for 10 minutes by vacuum filtration was 220.4 g, and the yield was 81%.

[0052] [Example 4]

Instead of adding ammonium nitrate as a dispersing agent, sodium sulfate was added (same chemical equivalent as ammonium nitrate), and the other procedures were carried out in the same manner as in Example 1. The produced colloidal silica was a particle having a concentration of 32.08% by weight, a primary particle size of 19.45 nm, and a secondary particle size of 30.7 nm. The kinematic viscosity was 2.44 mm ² / s. Further, the filtration amount for 10 minutes by vacuum filtration was 208.8 g, and the yield was 80%.

[0053] [Example 5]

To a Teflon-lined reaction flask equipped with a 1 L stirrer and reflux apparatus, 19 8. lg of tap water and 0 · 89 g of sodium hydroxide (containing 97% special grade) as an alkaline catalyst were added. The temperature was raised to ° C, and 66.2 g of the metallic silicon subjected to the inert treatment of Example 1 was dispersed in a slurry of 427.6 g of tap water, and the slurry was put into a slurry at a constant rate over 4 hours. Added at. In parallel with this, 15.3 g of a 10% by weight aqueous sodium hydroxide solution was added uniformly over 3 hours using a metering pump. Then, 10% by weight aqueous potassium nitrate solution 6. Og was added and mixed, and the dissolution reaction was continued for another 2 hours. After cooling, the mixture was cooled and filtered with 0.090mPa vacuum filter using a 90diam membrane filter. did. The resulting colloidal silica has a concentration of 23.2% by weight, a primary particle size of 18 nm, and a secondary particle size of 26η. m monodisperse particles with a kinematic viscosity of 2.15 mm ² / s. The filtration amount for 10 minutes by vacuum filtration was 145.8 g, and the yield was 83%. This colloidal silica was a stable low-viscosity sol with a viscosity of 2.28 mm ² / s, almost unchanged after storage at room temperature for 3 months.

[0054] [Comparative Example 1]

The procedure was the same as Example 1 except that no dispersant was added. The produced colloidal silica was monodispersed particles having a concentration of 29% by weight, a primary particle diameter of 21 nm, and a secondary particle diameter of 22 nm. The kinematic viscosity was as high as 4.95 mPa, and the filtration amount for 10 minutes by vacuum filtration was 6.5 g, and the yield was 58%.

[0055] [Comparative Example 2]

The same procedure as in Example 5 was performed except that no dispersant was added. The produced colloidal silica was a monodispersed particle having a concentration of 19.6% by weight, a primary particle diameter of 18 nm, and a secondary particle diameter of 28 nm. The kinematic viscosity was 2.60 mPa, which was very strong. In addition, the filtration amount for 10 minutes by vacuum filtration was 131. Og, and the yield was 74.6%. This colloidal silica was a sol that increased in viscosity after storage at room temperature for 3 months and increased in viscosity to 6.34 mm ² / s.

[0056] <Test Example 1: Effect of dispersant addition amount on filterability>

Metal silicon powder with an average particle size of 40 ΐη was pulverized to produce metal silicon with an average particle size of 5 ΐη. This metal silicon was oxidized by a drier in the atmosphere and subjected to an inert treatment. Otherwise, the procedure was as described in Example 1. Based on the method described in Example 1, changes in filterability with changes in the amount of dispersant added were confirmed. The results are shown in Table 1. In Table 1, the amount of ammonium nitrate added (% by weight) is relative to the amount of metallic silicon added.

[0057] [Table 1]

Glass viscosity with respect to the total amount of metallic silicon used iramV s) Yield (%) Amount of acid ammonium added (% by weight)

0 6. 3 4. 95 58

0. 54 63. 1 3. 592 73

0. 86 77. 6 2. 784 76

1. 07 q 4 7 S 1

1. 28 1 07. 4 2. 386 80

1. 71 1 12. 9 2. 297 80 [0058] As shown in Table 1, in the method for producing colloidal silica using metal silicon as a raw material, the addition of a dispersant in the reaction step of reacting metal silicon with water in the presence of an alkaline catalyst reduces the Viscosity colloidal silica can be produced. Therefore, according to the production method of the present invention, colloidal silica can be obtained with high filterability and yield.

[0059] In particular, when the added amount of the dispersant is 0.54 to; 1.71% by weight based on the total amount of metal silicon used, a yield of 73% or more, 3.592 mm ² / A kinematic viscosity of s or less and a filterability of 63. lg or more were confirmed.

[0060] <Relationship between silica particle size and addition rate of metallic silicon>

Example 6 and Comparative Example 3 were prepared as follows, and the relationship between the silica particle diameter and the addition rate of metallic silicon was examined.

[Example 6]

Metallic silicon powder with an average particle size of 40 was pulverized to produce metal silicon with an average particle size of 5 ΐη. This metal silicon was oxidized with an air atmosphere drier and subjected to an inert treatment. A slurry solution was prepared by dispersing 98.8 g of the obtained metal silicon powder in 334.8 g of ultrapure water.

A Teflon-lined reaction flask equipped with a 1 L stirrer and a reflux apparatus was charged with 166.43 g of an ultrapure aqueous solution containing 8 wt% NaOHO at a liquid temperature of 80 ° C. Thereto, all of the slurry solution was added at a constant rate using a metering pump over 4 hours. In parallel with this, 29.9 g of 10% by weight NaOH in water was added at a constant rate over 4 hours using a metering pump.

The dissolution reaction was further continued for 2 hours. After cooling, the reaction mixture was separated from unreacted residue by filtration under reduced pressure of 0.075 mPa with a 111, 90 diamm membrane filter. The primary particle diameter of silica contained in the produced colloidal silica was 22 nm.

[0061] [Comparative Example 3]

All of the slurry solution prepared by dispersing 98.8 g of deactivated metallic silicon in 334.8 g of ultrapure water was added at a constant rate using a metering pump over 8 hours. Then, the same operation as in Example 6 was carried out except that 29.9 g of NaOH 10% by weight aqueous solution was added using a metering pump at a constant rate over 8 hours. The particle size of silica contained in the produced colloidal silica was 35.8 nm. [0062] As described above, the primary particle diameter of silica contained in the resulting colloidal silica can be adjusted by controlling the rate of addition of metallic silicon to the alkaline aqueous solution. That is, the speed is faster! /, The smaller particles are produced, and the slower! /, The larger particles are produced! /.

[0063] <Method for controlling particle size of silica of colloidal silica>

In the step of adding the slurry of metallic silicon to the aqueous solution containing the alkaline catalyst, the change in the silica particle diameter accompanying the change in the addition rate was confirmed. In the following examples, no dispersant was used.

[Example 7]

Metallic silicon with an average particle size of 40 μm and Si content of 97% or more was crushed to produce metallic silicon with an average particle size of 5 μm. This metallic silicon was oxidized by a drier in the air atmosphere and inactivated. A slurry-like solution was prepared by dispersing 45.2 g of the obtained metal silicon powder in 531.69 g of ultrapure water.

A Teflon-lined reaction flask equipped with a 1 L stirrer and a reflux apparatus was charged with 223 g of an ultrapure aqueous solution containing 5 wt% NaOHO at a liquid temperature of 100 ° C. Thereto, all of the slurry solution was added at a constant rate using a metering pump over 1 hour.

The dissolution reaction was further continued for 4 hours. After cooling, 0.075 mPa was filtered under reduced pressure using a 1111, 90diamm membrane filter, and unreacted residues were separated by filtration to produce a high purity colloidal silica force. The colloidal silica had a particle size of 21.6 nm and a purity of 98%.

[0064] [Example 8]

The same procedure as in Example 7 was performed except that all of the slurry solution prepared by dispersing 45.2 g of the deactivated metal silicon powder in 531.69 g of ultrapure water was added over 10 minutes. The particle size of silica contained in the produced colloidal silica was 8.5 nm.

[0065] [Example 9]

The same procedure as in Example 7 was performed except that all of the slurry-like solution prepared by dispersing 45.2 g of the deactivated metal silicon powder in 531.69 g of ultrapure water was added over 20 minutes. The particle size of silica contained in the produced colloidal silica was 17.7 nm.

[Example 10] The same procedure as in Example 7 was performed except that all of the slurry solution prepared by dispersing 45.2 g of the deactivated metal silicon powder in 531.69 g of ultrapure water was added over 3 hours. The particle diameter of silica contained in the produced colloidal silica was 24.6 nm.

[0067] [Example 11]

The same procedure as in Example 7 was conducted, except that all of the slurry solution prepared by dispersing 45.2 g of the deactivated metal silicon powder in 531.69 g of ultrapure water was added over 4 hours. The particle diameter of silica contained in the produced colloidal silica was 28.2 nm.

[0068] [Example 12]

The same procedure as in Example 7 was performed, except that all of the slurry solution prepared by dispersing 45.2 g of the deactivated metal silicon powder in 531.69 g of ultrapure water was added over 2 hours. The particle diameter of silica contained in the produced colloidal silica was 22.6 nm.

[0069] Table 7 shows the addition time, primary particle size and yield of the metal silicon slurries of Examples 7 to 12

Yes

[0070] [Table 2]

As shown in Table 2, the primary particle size of the resulting colloidal silica can be adjusted by controlling the rate of addition of the slurry-like solution containing metallic silicon. That is, the faster the speed, the smaller the particles are produced, and the slower! /, The larger particles are produced! /.

As described above, the primary particle size of the resulting colloidal silica can be adjusted by controlling the rate of addition of metallic silicon to the alkaline aqueous solution.

Claims

The scope of the claims

[1] A step of obtaining colloidal silica by reacting metal silicon (Si) with water in an aqueous solution containing an alkaline catalyst and a dispersant, wherein the dispersant is selected from inorganic acids, organic acids, or salts thereof. A method for producing colloidal silica, which is one or more ionic substances.

2. The method for producing colloidal silica according to claim 1, wherein the dispersant is one or more inorganic acids selected from hydrochloric acid, nitric acid or sulfuric acid and / or a salt thereof.

[3] The dispersant is an inorganic acid salt, and the salt is Na, K, Li, NH, ammine or quaternary salt.

Four

3. The method for producing colloidal silica according to claim 2, wherein the colloidal silica is one or more selected from a salt with ammonium hydroxide.

[4] The dispersant is oxalic acid, citrate, malic acid, maleic acid, tartaric acid, tartaric acid, adipic acid, pimelic acid, succinic acid, malonic acid, fumaric acid, phthalic acid, formic acid, acetic acid, propionate. Acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-peptanoic acid, 2-methylhexanoic acid, n- 2. The method for producing colloidal silica according to claim 1, which is at least one organic acid selected from octanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid or lactic acid and / or a salt thereof.

[5] The dispersant is an organic acid salt, and the salt is Na, K, Li, NH, ammine or quaternary amine.

Four

5. The method for producing colloidal silica according to claim 4, wherein the colloidal silica is one or more selected from salts with monium hydroxide.

[6] The alkaline catalytic power is one or a mixture of metal monohydric hydroxides containing sodium (Na), potassium (K) or lithium (Li). A method for producing colloidal silica as described above.

[7] The method for producing colloidal silica according to any one of claims 1 to 6, wherein the kinematic viscosity after the colloidal silica is filtered and purified by a membrane filter having a pore diameter of 1 μm is 4 mm ² / or less. .

8. The method for producing colloidal silica according to any one of claims 1 to 7, wherein the colloidal silica has a silica concentration of 20% by weight or more.

[9] The method for producing colloidal silica according to claim 1, comprising at least the following steps.

[Step 3] Add the slurry-like liquid or metallic silicon prepared in Step 2 to the aqueous solution obtained in Step 1 at a substantially constant rate, or add the slurry prepared in Step 2 to the aqueous solution obtained in Step 1. The alkaline catalyst is added at a substantially constant rate in parallel with the addition of the liquid or metal silicon at a substantially constant rate.

[10] The colloidal silica according to claim 9, wherein in the step 3, colloidal silica containing silica having a desired particle diameter is obtained by controlling an addition rate of the slurry-like liquid or metal silicon. Production method.

[11] The addition rate of metallic silicon per hour as the addition rate;! To 9.5% by weight of the reaction liquid amount per hour; A method for producing colloidal silica.

12. The method for producing colloidal silica according to any one of claims 9 to 11, wherein the particle diameter force of silica contained in the colloidal silica obtained in the step 3 is 6 to 80 nm as a primary particle diameter.

[13] A method for producing colloidal silica comprising at least the following steps.

[Step I] Prepare an aqueous solution containing water and alkaline catalyst

[14] In the step III, colloidal silica containing silica having a desired particle diameter is obtained by controlling the addition speed of the slurry-like liquid in which metallic silicon is dispersed in water or metallic silicon. The manufacturing method of colloidal silica as described in any one of.