WO2010052945A1

WO2010052945A1 - Aspherical silica sol, process for producing the same, and composition for polishing

Info

Publication number: WO2010052945A1
Application number: PCT/JP2009/059810
Authority: WO
Inventors: 西田　広泰; 中山　和洋
Original assignee: 日揮触媒化成株式会社
Priority date: 2008-11-07
Filing date: 2009-05-28
Publication date: 2010-05-14
Also published as: TWI483898B; TW201018644A

Abstract

An aspherical silica sol which comprises a dispersion medium and, dispersed therein, aspherical fine silica particles which, when examined by the dynamic light scattering method, have an average particle diameter in the range of 3-150 nm, a minor-axis/major-axis ratio in the range of 0.01-0.8, and a specific surface area in the range of 10-800 m²/g and which have warty projections on the surface. A process for producing the silica sol is also provided. The aspherical fine silica particles contained in the aspherical silica sol have a peculiar structure different from the structure of ordinary aspherical fine silica particles. Due to this, the aspherical silica sol is excellent in physical properties such as suitability for filling, oil absorption, and electrical characteristics and in optical properties. The silica sol is useful, for example, as an abrasive material and a composition for polishing, and is excellent especially in polishing effect.

Description

Non-spherical silica sol, method for producing the same, and polishing composition

The present invention relates to a non-spherical silica sol in which non-spherical silica fine particles having a plurality of hook-shaped protrusions on the surface of silica fine particles as a nucleus are dispersed in a dispersion medium and a method for producing the same. The present invention also relates to a polishing composition containing the non-spherical silica sol.

In a non-spherical silica sol in which non-spherical silica fine particles are dispersed in a solvent, the shape of the non-spherical silica fine particles is known to be chain, beaded or oblong. Such non-spherical silica sols are used as various abrasives, for example.

As a method for producing non-spherical silica sol containing irregular particles, JP-A to 1-317115 (Patent Document 1), particle diameter measured by the image analysis method particle diameter measured by (D ₁₎ and the nitrogen gas adsorption method (D ₂ D ₁ / D ₂ is 5 or more, D ₁ is 40 to 500 millimicrons, and the thickness measured by electron microscope observation is uniform within the range of 5 to 40 millimicrons A method for producing a non-spherical silica sol in which elongated colloidal silica particles having an extension direction only in one plane are dispersed in a liquid medium is disclosed. In this method, (a) a predetermined amount of an aqueous solution containing a water-soluble calcium salt or magnesium salt is added to a predetermined colloidal aqueous solution of active silicic acid and mixed, (b) an alkali metal oxide, a water-soluble solution An organic base or a water-soluble silicate thereof is added and mixed so that the molar ratio of SiO ₂ / M ₂ O (wherein M represents an alkali metal atom or an organic base molecule) is 20 to 200. Step (c) is a production method comprising the step of heating the mixture obtained in the previous step at 60 to 150 ° C. for 0.5 to 40 hours.

In Japanese Patent No. 3441142 (Patent Document 4), the total number of colloidal silica particles having a major axis of 7 to 1000 nm and a minor axis / major axis ratio of 0.3 to 0.8 mm obtained by image analysis of an electron micrograph is described. A semiconductor wafer abrasive comprising a stable sol of silica occupying 50% or more of the number of particles has been proposed.

In JP-A-7-118008 (patent document 5), an aqueous solution of a water-soluble calcium salt, magnesium salt or a mixture thereof is added to an aqueous colloidal solution of active silicic acid, and an alkaline substance is added to the resulting aqueous solution. A part of the obtained mixture is heated to 60 ° C. or more to form a heel solution, the remainder is used as a feed solution, the feed solution is added to the heel solution, and water is evaporated during the addition to thereby evaporate SiO _2. A method for producing an elongated non-spherical silica sol obtained by concentrating the concentration to 6 to 30% by weight is disclosed.

In JP-A-8-279480 (Patent Document 6), (1) a method in which an alkali silicate aqueous solution is neutralized with a mineral acid and an alkaline substance is added and heat-ripened, and (2) the alkali silicate aqueous solution is subjected to cation exchange treatment. (3) A method of heating and aging active silicic acid obtained by hydrolyzing an alkoxysilane such as ethyl silicate, or (4) Fine silica powder Colloidal silica produced by, for example, a method of directly dispersing in an aqueous medium is a colloidal silica particle having a particle size of usually 4 to 1,000 nm, preferably 7 to 500 nm, dispersed in an aqueous medium. It is disclosed that SiO ₂ has a concentration of 0.5 to 50% by weight, preferably 0.5 to 30% by weight. It is described that the silica particles have a spherical shape, a distorted shape, a flat shape, a plate shape, an elongated shape, a fibrous shape, and the like.

Japanese Patent Laid-Open No. 11-214338 (Patent Document 7) discloses a silicon wafer polishing method using an abrasive mainly composed of colloidal silica particles, in which methyl silicate purified by distillation is converted into ammonia or methanol in a methanol solvent. There has been proposed a silicon wafer polishing method characterized by using colloidal silica particles obtained by reacting ammonia and ammonium salt with water as a catalyst and having a major axis / minor axis ratio of 1.4 or more.

International Publication No. WO 00/15552 (Patent Document 8) includes a spherical colloidal silica particle having an average particle diameter of 10 to 80 nm and a metal oxide-containing silica which joins the spherical colloidal silica particle, and an image analysis method for the spherical colloidal silica particle. The ratio D ₁ / D _{2 of the} measured particle diameter (D ₁ ) obtained by the above method and the measured particle diameter (D ₂ ) obtained by the nitrogen adsorption method is 3 or more, and this D ₁ is 50 to 500 nm. A non-spherical silica sol is described in which beaded colloidal silica particles in which colloidal silica particles are connected only in one plane are dispersed.

In addition, International Publication WO 00/15552 discloses a production method of (a) a predetermined colloidal solution of active silicic acid or an acidic non-spherical silica sol, an aqueous solution of a water-soluble metal salt, and an aqueous solution of the colloidal aqueous solution or acidic non-spherical silica sol. A step of preparing a mixed solution 1 by adding an amount of 1 to 10% by weight as a metal oxide with respect to ₂ , (b) an acidic spherical non-particle having an average particle size of 10 to 80 nm and a pH of 2 to 6 The spherical silica sol has a ratio A / B (weight ratio) of 5 to 100 between the silica content (A) derived from the acidic spherical non-spherical silica sol and the silica content (B) derived from the mixed solution 1, and the acidic mixing the total silica content of the mixture 2 obtained by mixing (a + B) is added an amount containing SiO ₂ concentration of 5 to 40 wt% in the mixture 2 of the spherical non-spherical silica sol with the mixed solution 1 And (c) a method comprising adding an alkali metal hydroxide, a water-soluble organic base or a water-soluble silicate to the obtained mixture 2 so as to have a pH of 7 to 11, and mixing and heating. Is described.

Japanese Patent Application Laid-Open No. 2001-11433 (Patent Document 9) discloses a water-soluble II value in an aqueous colloidal solution of active silicic acid containing 0.5 to 10% by weight as SiO ₂ and having a pH of 2 to 6. Alternatively, an aqueous solution containing a valent metal salt alone or in combination of two or more metal oxides with respect to SiO ₂ of the colloidal aqueous solution of the active silicic acid is designated as MO (in the case of a valent metal salt, MO, M ₂ O _{3 in} the case of a metal salt of the above, where M represents a II or III valent metal atom, and O represents an oxygen atom) and mixed in an amount of 1 to 10% by weight. Then, an acidic spherical non-spherical silica sol having an average particle diameter of 10 to 120 nm and a pH of 2 to 6 is added to the obtained mixed liquid (1), the silica content (A) derived from the acidic spherical non-spherical silica sol, and the mixed liquid (1 ) The ratio A / B (weight ratio) to the silica content (B) derived from 00, and the acidic spherical non-spherical silica sol and the mixture (1) the total silica content of the mixture obtained by mixing (2) and (A + B) is SiO ₂ concentration of 5 to 40 wt% in the mixed solution (2) Then, an alkali metal hydroxide or the like is added to the mixed solution (2) so as to have a pH of 7 to 11 and mixed, and the obtained mixed solution (3) is heated to 100 to 200 ° C. Describes a method for producing a beaded non-spherical silica sol heated at 0.5 to 50 hours.

Japanese Patent Laid-Open No. 2001-48520 (Patent Document 10) discloses a composition having a silica concentration of 1 to 8 mol / liter, an acid concentration of 0.0018 to 0.18 mol / liter, and a water concentration of 2 to 30 mol / liter. The alkyl silicate is hydrolyzed with an acid catalyst without using a solvent, diluted with water so that the silica concentration is in the range of 0.2 to 15 mol / liter, and then the alkali catalyst is used so that the pH becomes 7 or more. Is heated to advance the polymerization of silicic acid, the average diameter in the thickness direction obtained by electron microscope observation is 5 to 100 nm, and the length is 15 to 50 times the length of the amorphous amorphous A method for producing a non-spherical silica sol in which silica particles are dispersed in a liquid dispersion is described.

Japanese Patent Laid-Open No. 2001-150334 (Patent Document 11) discloses an acidic aqueous solution of activated silicic acid having a SiO ₂ concentration of about 2 to 6% by weight obtained by decation treatment of an aqueous solution of an alkali metal silicate such as water glass. In addition, an alkaline earth metal such as a salt of Ca, Mg, Ba or the like is added at a weight ratio of 100 to 1500 ppm with respect to SiO ₂ of the above active silicic acid in terms of its oxide, and further SiO ₂ / M _{2 in} this solution. O (M represents an alkali metal atom, NH ₄ or a quaternary ammonium group.) The liquid obtained by adding the alkali substance in an amount of 20 to 150 in molar ratio is initially used as the heel liquid. SiO ₂ / M ₂ O of SiO ₂ concentration of from 2 to 6% by weight obtained and 20-150 Te (M is the same) the active silicic acid aqueous solution having a molar ratio as charged liquid, 60 ~ 0.99 ° C. The charge liquid the initially heel solution, per hour, the charge liquid SiO ₂ / initially at a rate of 0.05-1.0 as a weight ratio of the heel solution SiO _2, while evaporating and removing water from the liquid (Matahase A method for producing a non-spherical silica sol having a distorted shape is described.

In Japanese Patent Laid-Open No. 2003-133267 (Patent Document 12), the average particle diameter is in the range of 5 to 300 nm as polishing particles capable of suppressing dishing (overpolishing) and polishing the substrate surface flatly. Abrasive particles characterized by comprising a group of irregularly shaped particles in which two or more primary particles are combined are described. In particular, the particles constituting the irregularly shaped particle group occupy the total number of primary particles in the abrasive particles. There is a description that abrasive particles having a number of secondary particles in the range of 5 to 100% are effective.

Japanese Patent Application Laid-Open No. 2004-288732 (Patent Document 13) discloses a semiconductor polishing slurry characterized by containing non-spherical colloidal silica, an oxidizing agent and an organic acid, and the balance being water. Among them, non-spherical colloidal silica (major axis / minor axis) having a major axis / minor axis of 1.2 to 5.0 has been proposed, and the same non-true colloid is disclosed in Japanese Patent Application Laid-Open No. 2004-311652 (Patent Document 14). Spherical colloidal silica is disclosed.

Regarding silica-alumina-coated chain non-spherical silica sol, JP-A No. 2002-3212 (Patent Document 15) discloses (a) an alkali metal silicate aqueous solution of 0.05 to 5.0% by weight as SiO _2. A step of adding a silicic acid solution to adjust SiO ₂ / M ₂ O (molar ratio, M is an alkali metal or quaternary ammonium) of the mixed solution to 30 to 60, (b) the silicic acid solution adding step Before, during or after the addition step, a step of adding one or more metal compounds of divalent to tetravalent metals, (c) the mixed solution at an arbitrary temperature of 60 ° C. or higher (D) Next, a step of adding a silicic acid solution again to the reaction solution to make SiO ₂ / M ₂ O (molar ratio) in the reaction solution 60 to 200, (e) Alkaline silicate aqueous solution and alkali Adding the aluminate solution at the same time, silica consists - method for producing alumina coated linear non-spherical silica sol is disclosed.

As an example having a protrusion-like structure on the surface of silica-based fine particles, JP-A-3-257010 (Patent Document 16) discloses a continuous surface having a size of 0.2 to 5 μm as observed with an electron microscope on the surface of silica particles. A description of silica particles having uneven projections, an average particle diameter of 5 to 100 μm, a specific surface area obtained by the BET method of 20 m ² / g or less, and a pore volume of 0.1 mL / g or less. is there.

Japanese Patent Application Laid-Open No. 2002-38049 (Patent Document 17) discloses silica-based fine particles having substantially spherical and / or hemispherical protrusions on the entire surface of the seed particles, and the protrusions are seeded by chemical bonding. There is a description of silica-based fine particles that are bound to the particles. Furthermore, (A) a step of hydrolyzing and condensing a specific alkoxysilane compound to produce polyorganosiloxane particles, (B) a step of treating the polyorganosiloxane particles with a surface adsorbent, and (C) the above ( There is a description of a method for producing silica-based fine particles, including a step of forming protrusions using the alkoxysilane compound on the entire surface of the polyorganosiloxane particles surface-treated in step B).

Japanese Patent Application Laid-Open No. 2004-35293 (Patent Document 18) discloses silica-based particles having substantially spherical and / or hemispherical protrusions on the entire surface of the seed particles, and the protrusions are seeded by chemical bonding. Silica-based particles are disclosed that are bound to particles and have different compressive elastic moduli at 10% compression between seed particles and protrusions.

However, the particles described in JP-A-3-257010 (Patent Document 16) are composed only of silica having an average particle diameter of 5 to 100 μm, and are disclosed in JP-A-2002-38049 (Patent Document 17). Only silica-based particles having an average particle diameter of 0.5 to 30 μm are disclosed, and the same applies to JP-A-2004-35293 (Patent Document 18).

JP-A-1-317115 Japanese Patent Laid-Open No. 4-65314 JP-A-4-187512 Japanese Patent No. 3441142 Japanese Patent Application Laid-Open No. 7-118008 JP-A-8-279480 JP-A-11-214338 International Publication WO00 / 15552 JP 2001-11433 A JP 2001-48520 A JP 2001-150334 A JP 2003-133267 A JP 2004-288732 A JP 2004-311652 A JP 2002-3212 A JP-A-3-257010 JP 2002-38049 A JP 2004-35293 A

An object of the present invention is to provide a silica sol having non-spherical silica fine particles having excellent characteristics such as abrasiveness and having a small average particle diameter and dispersed in a dispersion medium, and a method for producing the same. Another object is to provide a polishing composition containing the non-spherical silica sol.

The present invention that solves the above-mentioned problems has an average particle diameter measured by dynamic light scattering of 3 to 200 nm, a minor axis / major axis ratio of 0.01 to 0.8, and a specific surface area of 10 to 800 m. ^The non-spherical silica sol is characterized in that non-spherical silica fine particles in the range of ² / g and having a plurality of hook-shaped protrusions on the surface are dispersed in a dispersion medium.

A preferred embodiment of the non-spherical silica sol according to the present invention is as follows. First, from any point on the outer edge of the non-spherical silica fine particle on a plane including the long axis of the non-spherical silica fine particle having the hook-shaped protrusion. , Y is a distance to an intersection B between the long axis passing through a point on the outer edge and a line orthogonal to the major axis, and from the one intersection A of the outer edge of the non-spherical silica fine particle to the major axis, the intersection Examples of the non-spherical silica sol in which when the XY curve is drawn with the distance to B as X, the XY curve has a plurality of maximum values.

As a second preferred embodiment, on a plane including the long axis of the non-spherical silica fine particles having the ridge-like protrusions, the point passes from the arbitrary point on the outer edge of the non-spherical silica fine particle to the point on the outer edge. Examples of the non-spherical silica sol include a variation coefficient of the distance Y in the range of 5 to 50%, where Y is the distance to the intersection B between the straight line perpendicular to the long axis and the long axis.
As a third preferred embodiment, there may be mentioned the nonspherical silica sol in which the number of nonspherical silica fine particles having ridge-like projections is 50% or more of the total number of silica fine particles as a dispersoid.
As a fourth preferred embodiment, the non-spherical silica sol in which the non-spherical silica fine particles having ridge-like protrusions are composed of [SiO _4/2 ] units can be mentioned.
As a fifth preferred embodiment, the non-spherical silica sol in which the non-spherical silica fine particles having ridge-like projections are polysiloxanes composed of [SiO _4/2 ] units obtained by hydrolysis of tetraethoxysilane. Can be mentioned.
A sixth preferred embodiment includes the nonspherical silica sol, wherein the ratio of sodium contained in the nonspherical silica fine particles is 100 mass ppm or less.

Another invention in the present application is a polishing composition comprising the abrasive comprising the non-spherical silica sol and the non-spherical silica sol.

Another invention in the present application is that, in the presence of an electrolyte comprising a salt of a strong acid (the equivalent number of the electrolyte is represented by (EE)), 100 parts by mass of the following A liquid (in terms of silica), 50 to 2500 parts by mass of B liquid When adding non-spherical seed silica fine particles by adding (silica conversion), B liquid is added so that the equivalent ratio of the alkali to the electrolyte (EA / EE) is in the range of 0.4 to 8. The method for producing the non-spherical silica sol.
Liquid A: Non-spherical seed silica fine particles having an average particle diameter measured by a dynamic light scattering method in the range of 3 to 200 nm and a minor axis / major axis ratio in the range of 0.01 to 0.8 are dispersed in the dispersion medium. Nonspherical seed silica sol B liquid: An aqueous alkali silicate solution (the number of equivalents of alkali contained in B liquid is represented by (EA))
As a preferred embodiment of the method for producing the non-spherical silica sol, the liquid B and the electrolyte are added to the liquid A at a temperature range of 40 to 150 ° C. over 15 minutes to 10 hours, respectively, and then aged. A method for producing a non-spherical silica sol can be mentioned.

In another aspect of the present invention, the temperature range of a mixed solvent containing a water-soluble organic solvent and water is maintained at 30 to 150 ° C., and the mixed solvent is represented by 1) the following general formula (1) A water-soluble organic solvent solution of a tetrafunctional silane compound and 2) an alkali catalyst solution are added simultaneously or intermittently. After the addition is completed, the liquid is further maintained in a temperature range of 30 to 150 ° C. In producing the non-spherical silica sol by hydrolytic condensation of the tetrafunctional silane compound, the molar ratio of water to the tetrafunctional silane compound is in the range of 2 to 4. It is a manufacturing method.

(In the formula (1), R is an alkyl group having 2 to 4 carbon atoms.)
As a preferred embodiment of the method for producing the non-spherical silica sol, there can be mentioned the method for producing the non-spherical silica sol in which the tetrafunctional silane compound is tetraethoxysilane.

Since the non-spherical silica fine particles contained in the non-spherical silica sol according to the present invention have a unique structure different from ordinary non-spherical silica fine particles, the non-spherical silica sol according to the present invention has a filling property, an oil absorption property, and an electric property. It has excellent physical properties and optical properties such as, for example, is useful as an abrasive and a polishing composition, and is particularly excellent in the effect of polishing properties.

FIG. 1 is a schematic diagram of how to determine the number of local maximum values. FIG. 2 is a schematic diagram of how to obtain the variation coefficient of the distance Y. FIG. 3 is a scanning electron micrograph (magnification: 250,000 times) of the non-spherical silica sol prepared in Example 3.

[Non-spherical silica sol]
The non-spherical silica sol of the present invention has an average particle diameter measured by a dynamic light scattering method of 3 to 200 nm, a minor axis / major axis ratio of 0.01 to 0.8, and a specific surface area of 10 to 800 m ^2. The non-spherical silica fine particles having a range of / g and having a plurality of hook-shaped protrusions on the surface are dispersed in a dispersion medium.

The non-spherical silica fine particles that are the dispersoid of the non-spherical silica sol according to the present invention preferably have a minor axis / major axis ratio in the range of 0.01 to 0.8. In the case of the minor axis / major axis ratio in this range, a shape that is regarded as an unusual shape such as a fiber shape, a column shape, or a spheroid shape, that is, a shape that is not regarded as a spherical shape is taken. When the minor axis / major axis ratio exceeds 0.8, the particles are almost spherical. The case where the minor axis / major axis ratio is less than 0.01 includes the case where the production is not easy. A more preferable range of the minor axis / major axis ratio is 0.1 to 0.7, and an even more preferable range is 0.12 to 0.65.

The non-spherical silica sol according to the present invention is structurally different from conventional non-spherical silica sols such as non-spherical silica sols in that the non-spherical silica fine particles as a dispersoid have a plurality of hook-shaped protrusions on the surface thereof. It is. That is, the non-spherical silica fine particles contained in the non-spherical silica sol according to the present invention can be said to be non-spherical confetti-like silica fine particles or saddle-shaped projection-coated non-spherical silica fine particles. The non-spherical silica sol according to the present invention has a unique effect in various uses, for example, a use for polishing, a filler for a resin or a film forming component, a filler for an ink receiving layer, etc. It becomes possible to show. The hook-like protrusions can be confirmed by, for example, an electron micrograph of a non-spherical silica sol, and have a structure protruding from the peripheral portion or a swollen structure on the particle surface.

The non-spherical silica fine particles according to the present invention may be those using water glass or the like as a raw material as described later, or those prepared using alkoxysilane as a raw material. Examples of the latter include non-spherical silica sol, wherein the non-spherical silica fine particles are composed of [SiO _4/2 ] units. A method for producing such a non-spherical silica sol will be described later.

About the non-spherical silica fine particles, preferably, the long axis passes through a point on the outer edge from an arbitrary point on the outer edge of the non-spherical silica fine particle on a plane including the long axis of the non-spherical silica fine particle. XY curve where Y is the distance to the intersection B of the straight line orthogonal to the long axis and the long axis, and X is the distance from one intersection A of the outer edge of the non-spherical silica fine particle to the long axis It is desirable that the XY curve has a plurality of maximum values. For this, the major axis of the non-spherical silica fine particles was determined in an image of a scanning electron micrograph (250,000 to 500,000 times) of the non-spherical silica fine particles, and the total length of the long axis was divided into 40 equal parts. Each point (point B) and a straight line perpendicular to the point are stretched to one side of the fine particle, and the distance between the point where the fine particle intersects the outer edge is recorded as Y. Further, let X be the distance between one point (point A) of the two intersections between the outer edge of the non-spherical silica fine particle and the long axis and the corresponding point (point B). By plotting the Y value corresponding to each X with Y as the vertical axis and X as the horizontal axis, the XY curve can be drawn, and the number of local maximum values of this XY curve can be measured. In the present invention, for non-spherical silica fine particles, such measurement is performed for 50 particles, and the average of the number of local maximum values is 2 or more, the non-spherical silica fine particles have the plurality of local maximum values. It was decided to handle it as having. An outline of how to determine the number of local maximum values is shown in FIG. In FIG. 1, “1” represents the major axis, “2” represents the outer edge, “3” represents the position at which the maximum value is obtained, “4” represents the 40-segment line, and “L” represents the length in the major axis direction.

The number of local maximum values is preferably in the range of 2 to 10, more preferably in the range of 3 to 8. Note that the number of maximum values may be obtained by measurement with an analytical instrument.

Further, the non-spherical silica fine particles more preferably, on a plane including the long axis of the fine particles, from any point on the outer edge of the non-spherical silica fine particles through the point on the outer edge and the long axis When the distance to the intersection B between the orthogonal straight line and the long axis is Y, it is desirable that the variation coefficient of the distance Y is in the range of 5 to 50%. The measurement of the coefficient of variation of the distance Y from the outer edge of the fine particles to the long axis in the present invention was calculated by the following method.
1) Measure the distance (long axis radius M) from the center point of the long axis (located at the position that bisects the long axis of the fine particles) to one of the outer edges of the fine particles on the long axis. Plot from 0 to 50% in 5% increments for the length of the major axis radius M from the center point.
2) A straight line perpendicular to the major axis is drawn in each plot, and the distance Y from the point where the straight line intersects the outer edge of the fine particle on one side to the plot is measured.
3) Regarding the coefficient of variation (CV value) for the distance Y from the outer edge of the fine particle to the long axis, on the long axis, the range of 0 to 10% of the long axis radius M from the center point is 0 to 20%. Calculate the variation coefficient (CV value) of distance Y in each of the range, 0-30% range, 0-40% range, 0-50% range to obtain 5 types of variation coefficient (CV value) The maximum coefficient of variation (CV value) among them is defined as the coefficient of variation (CV value) for the distance Y in the particle.
4) The above measurements 1) to 3) were performed on 50 particles, and the average value was adopted as the coefficient of variation (CV value) for the distance Y in the non-spherical silica fine particles. An outline of how to obtain the coefficient of variation of the distance Y value is shown in FIG. In FIG. 2, “1”, “2”, and “L” are the same as those in FIG. 1, “M” is the length of the radius in the major axis direction, and “N” is a length of 50% of M. Represents.

The variation coefficient (CV value) of the distance Y is obtained from the relational expression of variation coefficient (CV value) [%] = (standard deviation of distance Y (σ) / average value of distance Y (Ya)) × 100. It is done.

As described above, from a point on the outer edge of the non-spherical silica fine particle on a plane including the long axis of the non-spherical silica fine particle, a straight line passing through the point on the outer edge and orthogonal to the long axis and the long axis When the XY curve is drawn with the distance to the intersection B of Y being Y and the distance from one intersection A of the outer edge of the non-spherical silica fine particle to the major axis being X, the distance from the intersection B is X. When the Y curve has a plurality of maximum values, the non-spherical silica fine particles have ridge-like projections, and in such non-spherical silica fine particles, the coefficient of variation (CV) with respect to the distance Y from the outer edge to the major axis. (Value) in the range of 5 to 50% indicates that there is a significant variation in the length of the distance Y from the outer edge of the particle to the major axis, and there are undulations on the surface of the non-spherical silica fine particles. Will be shown.

When the average number of the maximum values is 2 or more and the coefficient of variation (CV value) for the distance Y from the outer edge to the long axis is less than 5%, the surface of the non-spherical silica fine particles is slightly undulated. Cases or cases where there is substantially no undulations. When the coefficient of variation (CV value) for the distance Y from the outer edge to the long axis is 50% or more, it is not easy to prepare, and such particles have a problem in robustness due to the structure. May come out.

The coefficient of variation (CV value) for the distance Y from the outer edge to the long axis is more preferably in the range of 7 to 45%. Further, it is more preferably in the range of 10 to 40%.

平均 The average particle size of the non-spherical silica fine particles that are the dispersoid of the non-spherical silica sol according to the present invention is preferably in the range of 3 to 200 nm in terms of the average particle size measured by the dynamic light scattering method. If the average particle diameter is in this range, for example, in each of the above applications, an effective effect based on the shape of the non-spherical silica sol according to the present invention is likely to occur. When the average particle diameter exceeds 200 nm, although depending on the size of the raw material fine particles, the tendency to flatten the hook-shaped protrusions is generally increased because the built-up process generally proceeds excessively. When the average particle diameter is less than 3 nm, it is not easy to prepare non-spherical silica fine particles as a raw material. The average particle diameter of the non-spherical silica fine particles measured by the dynamic light scattering method is preferably in the range of 10 to 195 nm, and more preferably in the range of 20 to 195 nm.

For the non-spherical silica fine particles having an average particle diameter range of 3 to 200 nm by the dynamic light scattering method, the non-spherical silica fine particles having a long axis average diameter of 3 to 190 nm by the image analysis method are used. Corresponds. Here, the long axis means the maximum diameter of the non-spherical silica fine particles. In the present application, the image analysis method means the maximum diameter of particles measured in a scanning electron micrograph (magnification 250,000 to 500,000 times). Specific measurement methods are shown in the examples. The average value of the major axis is preferably in the range of 10 to 180 nm, and more preferably in the range of 15 to 170 nm.

The non-spherical silica fine particles have a specific surface area in the range of 10 to 800 m ² / g, preferably 20 to 500 m ² / g, and more preferably 30 to 300 m ² / g. When the specific surface area is less than 10 m ² / g, non-spherical silica fine particles having almost no wrinkle-like protrusions on the surface are contained, which is not preferable. Moreover, it is not easy to prepare particles having a specific surface area larger than 800 m ² / g as the non-spherical silica fine particles according to the present invention. The specific surface area is a numerical value determined by the BET method (nitrogen adsorption method).

The solvent in which the non-spherical silica fine particles are dispersed may be water, an organic solvent, or a mixed solvent thereof. Examples thereof include alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, water-soluble organic solvents such as ethers, esters and ketones.

The non-spherical silica sol according to the present invention is obtained by dispersing silica fine particles containing non-spherical silica fine particles having a plurality of hook-shaped protrusions on the surface as a dispersoid in a dispersion medium. Need not be non-spherical silica fine particles having a plurality of hook-shaped protrusions on the surface. The higher the ratio of the number of non-spherical silica fine particles having a plurality of hook-shaped protrusions on the surface to the total number of silica fine particles that are dispersoids, the better. The ratio is preferably 50% or more, and more preferably 60% or more. The higher the ratio, the easier it is to obtain a practical polishing rate when the spherical silica sol is used for polishing.

The silica concentration of the non-spherical silica sol according to the present invention is usually preferably in the range of 1 to 50% by mass, and more preferably in the range of 5 to 30% by mass.

The production method of the non-spherical silica sol according to the present invention is not necessarily limited, but is usually prepared by the first production method or the second production method of the non-spherical silica sol described later.

The first method for producing a non-spherical silica sol includes a case where a commercially available non-spherical silica sol is used as a raw material, and particularly includes a case where a non-spherical silica sol prepared using water glass as a raw material is used. In this case, although the non-spherical silica sol according to the present invention can be prepared at low cost, sodium derived from the raw water glass or the like may remain at a relatively high concentration in the non-spherical silica fine particles. When such a non-spherical silica sol according to the present invention is applied to an abrasive of an electronic material or a semiconductor material, for example, there is a possibility of causing contamination with sodium.

On the other hand, in the second method for producing a non-spherical silica sol, a tetrafunctional silane compound is used as a raw material, so that there is no possibility that sodium is mixed into the non-spherical silica fine particles. In this case, the content of sodium contained in the non-spherical silica fine particles can be reduced to 100 ppm by mass or less. For example, the present non-spherical silica sol can be suitably used as an abrasive for electronic materials or semiconductor materials.

The non-spherical silica fine particles prepared by the second method for producing the non-spherical silica sol are obtained by hydrolysis of a tetrafunctional silane compound such as tetraethoxysilane, and are composed of [SiO _4/2 ] units. It becomes a polysiloxane structure.

[First production method of non-spherical silica sol]
A first method for producing a non-spherical silica sol according to the present invention includes a non-spherical seed silica sol in which non-spherical seed silica fine particles are dispersed in a dispersion medium (hereinafter referred to as “Liquid A”) from a strong acid salt. In the presence of an electrolyte, an alkali silicate aqueous solution (hereinafter, this alkali silicate aqueous solution is referred to as “Liquid B”) is added to grow B particles with respect to 100 parts by mass of silica of liquor A. 50 to 2500 parts by mass of silica is added so that the ratio of the number of equivalents of alkali (EA) to the number of equivalents of electrolyte (EE) (EA / EE) in the liquid B is in the range of 0.4 to 8. It is. Here, the non-spherical seed silica fine particle is a silica used for producing non-spherical silica fine particles having the ridge-like projections according to the present invention by growing silica on the surface of the non-spherical silica fine particles. Refers to fine particles.

Hereinafter, the method for producing the non-spherical silica sol of the present invention will be specifically described.
Non-spherical seed silica sol (A liquid)
For the liquid A, the average particle diameter measured by the dynamic light scattering method is in the range of 3 to 200 nm, the minor axis / major axis ratio is in the range of 0.01 to 0.8, and the specific surface area is 15 to 800 m ² / g. A non-spherical silica sol obtained by dispersing non-spherical silica fine particles in a range in a dispersion medium is used.

In the method for producing a non-spherical silica sol of the present invention, the method for producing a non-spherical seed silica sol used as a raw material is not particularly limited, and a commercially available non-spherical silica sol or a known non-spherical silica sol may be applied. it can. A known non-spherical silica sol can be obtained, for example, by the following production methods (I) to (V).
(I) A silicic acid solution is added to an aqueous solution of a water-soluble silicate, and SiO ₂ / M ₂ O [M is selected from alkali metal, tertiary ammonium, quaternary ammonium or guanidine] (molar ratio) Is prepared by adding a silicic acid solution intermittently or continuously at a temperature of 60 to 200 ° C. to prepare a silica sol having a pH of 7 to 9 In the range of 60 to 98 ° C., and a method for producing an anisotropic silica sol (see JP2007-153671)
(II) In a silica sol having a pH of 2 to 8 in which silica fine particles having an average particle diameter of 3 to 25 nm are dispersed, a polymetal salt compound is added to 100 parts by weight of the silica solid content of the silica sol. Addition of 0.01 to 70 parts by weight and heating at 50 to 160 ° C. (see Japanese Patent Application Laid-Open No. 2007-153672)
(III) Silica sol having an average particle size in the range of 3 to 20 nm is decationized to adjust the pH to 2 to 5, then deanized, and then adjusted to pH 7 to 9 by adding an alkaline aqueous solution. And then heating at 60 to 250 ° C. (see Japanese Patent Application Laid-Open No. 2007-145633)
(IV) An alkaline aqueous solution is added to the silicic acid solution (a) to adjust the pH to 10.0 to 12.0, and the silicic acid solution (b) and a water-soluble metal having a valence of 2 or more under a temperature condition of 60 to 150 ° C. A method for producing an anisotropic shaped silica sol, wherein a mixture with a salt is added continuously or intermittently (see JP2007-153692A)
(V) A method for producing an anisotropic shaped silica sol according to the following steps (1) and (2) (see WO2007 / 018069).
(1) The silica hydrogel obtained by neutralizing silicate with an acid is washed to remove salts, and the molar ratio of SiO ₂ / M ₂ O (M: Na, K, NH ₃ ) is 30 to 500. (2) Step of obtaining silica sol by heating in the range of 60 to 200 ° C. after adding alkali so that the pH becomes 9 to 12.5, temperature 60 to 200 ° C. Step of continuously or intermittently adding a silicic acid solution at 200 ° C. In the method of the present invention, such raw material non-spherical silica sol is diluted with pure water as necessary to obtain a silica solid content concentration of 2 It is desirable to adjust to ~ 40%.

The non-spherical seed silica sol used as the liquid A is a silica sol having a short diameter / long diameter ratio of non-spherical silica fine particles as a dispersoid in the range of 0.01 to 0.8, and the non-spherical silica sol to be obtained Those having an average particle size smaller than or equivalent to that of the non-spherical silica fine particles which are the dispersoid of the above are used. A more preferable range of the minor axis / major axis ratio is 0.1 to 0.7, and an even more preferable range is 0.12 to 0.65.

With respect to the non-spherical seed silica fine particles that are the dispersoid of the non-spherical seed silica sol, the average particle diameter by the dynamic light scattering method is preferably in the range of 3 to 200 nm, more preferably in the range of 5 to 150 nm, and further preferably. Is in the range of 10 to 120 nm.

The specific surface area of the non-spherical seed silica fine particles is preferably in the range of, for example, 5 to 800 m ² / g.

The concentration of the non-spherical seed silica sol varies depending on the particle diameter of the non-spherical seed silica fine particles, but is preferably in the range of 0.005 to 10% by mass, more preferably 0.01 to 5% by mass as silica. When the silica concentration is less than 0.005% by mass, the amount of non-spherical seed silica fine particles serving as core particles is too small, and it is necessary to slow down the supply rate of the alkali silicate aqueous solution (liquid B) and / or the electrolyte. If the speed is not lowered, new fine particles are generated and act as core particles, so that the particle size distribution of the obtained sol may be broad, which is inefficient in preparing the non-spherical silica sol. If the concentration of the non-spherical seed silica sol exceeds 10% by mass, the concentration may be too high and the core particles may aggregate when supplying the alkali silicate aqueous solution and / or the electrolyte. In this case also, the particle size distribution is broad. And tend to produce particles adhered to each other, which is undesirable for the preparation of non-spherical silica sols.

The pH of the non-spherical seed silica sol is 8-12, especially 9. Desirably, it is in the range of 5 to 115. When the pH is less than 8, the reactivity of the surface of the core particles is low, so that the supplied alkali silicate (liquid B) is deposited on the surface at a slow rate. As a result, unreacted alkali silicate increases or new fine particles Is generated, and the particle size distribution of the resulting sol may be broad or aggregated particles may be obtained, which is not desirable for the efficient production of a non-spherical silica sol. When the pH exceeds 12, the silica solubility increases, so that the silica deposition is delayed, and therefore the particle growth tends to be delayed.

The pH adjustment of the non-spherical seed silica sol can be performed by adding an alkali. Specifically, alkali metal hydroxides such as NaOH and KOH, ammonia water, quaternary ammonium hydroxide, amine compounds, and the like can be used. The temperature at which the non-spherical seed silica sol is prepared is not particularly limited, and is usually in the range of 10 to 30 ° C.
Silicic acid alkali aqueous solution (liquid B)
In the present invention, an electrolyte and an alkali silicate aqueous solution (liquid B) are added to the liquid A to grow silica fine particles. The electrolyte can be partly or wholly added to the liquid A in advance, but may be added continuously or intermittently together with the alkali silicate aqueous solution of the liquid B.

Examples of the alkali silicate used as the liquid B include alkali silicate salts such as LiOH, NaOH, KOH, RbOH, CsOH, NH ₄ OH, and quaternary ammonium hydride. Among these, sodium silicate (water glass), potassium silicate, etc. can be used suitably. In addition, an alkali silicate aqueous solution obtained by hydrolyzing a hydrolyzable organic compound such as tetraethylorthosilicate (TEOS) using excess NaOH or the like is also suitable.

It is desirable that the temperature of the non-spherical seed silica sol when adding the alkaline silicate aqueous solution of the solution B is in the range of 40 to 150 ° C., more preferably 60 to 100 ° C. When the temperature is less than 40 ° C., the reaction rate of silicic acid is slow, and there are cases where unreacted silicic acid increases or particles having a desired size cannot be obtained. When the temperature of the non-spherical seed silica sol exceeds 150 ° C., there is a problem that the operating pressure becomes too high and the cost of the apparatus becomes high and the production capacity is lowered and the economy is lowered. When the temperature exceeds 150 ° C., the effect of increasing the reaction rate and particle growth rate is practically small.

The addition amount of the aqueous solution of alkali silicate in the B liquid (silica conversion) depends on the temperature and reaction time when growing the core particles, but is usually 50 to 2500 with respect to 100 parts by mass of silica contained in the A liquid. It is preferable that it is the range of a mass part. If the amount is less than 50 parts by mass, the particle growth itself is low, and it is not easy to efficiently obtain a non-spherical silica sol exhibiting the necessary surface roughness. When the amount exceeds 2500 parts by mass, the growth of the core particles proceeds excessively, and thus the tendency to become silica fine particles having a flattened surface increases. A more preferable amount of addition of B liquid (in terms of silica) is in the range of 80 to 1800 parts by mass.
Electrolyte As the electrolyte used in the present invention, a conventionally known acid and base salt which is soluble in water can be used. In particular, an electrolyte composed of a salt of a strong acid is preferable because it can accept alkali alkali silicate and at this time forms silicic acid used for the growth of core particles. Examples of water-soluble electrolytes composed of such strong acid salts include sodium salts, potassium salts, lithium salts, rubidium salts, cesium salts, ammonium salts, calcium salts, and magnesium salts of strong acids such as sulfuric acid, nitric acid, and hydrochloric acid. It is done. Alum which is a double salt of sulfuric acid such as potassium alum and ammonium alum is also suitable.

The amount of the electrolyte is such that the ratio (EA / EE) of the number of alkali equivalents (EA) to the number of equivalents of electrolyte (EE) (EA / EE) contained in the liquid B is 0.4 to 8, particularly 0.8. It is preferable to be in the range of 4-5. When the ratio (EA / EE) is less than 0.4, the electrolyte salt concentration in the dispersion may be too high and the particles may aggregate. When the ratio (EA / EE) exceeds 8, the amount of electrolyte is small and the particle growth rate becomes insufficient, and there is no difference from the conventional growth of core particles by supplying an acidic silicic acid solution. On the other hand, when the ratio (EA / EE) exceeds 8, the above-mentioned electrolyte accepts alkali silicate alkali, so that generation of silicic acid used for particle growth of core particles is reduced, and particles having a desired particle diameter are obtained. There are times when you can't.

The electrolyte preferably has a concentration of the electrolyte in the dispersion in the range of 0.05 to 10% by mass. A range of 0.1 to 5% by mass is recommended. Such an electrolyte may be partly or wholly added separately from the alkali silicate aqueous solution (B solution), or may be added continuously or intermittently with the alkali silicate aqueous solution (B solution). . The amount of electrolyte at this time is also preferably in the relationship between the amount of alkali silicate and the ratio of the number of equivalents described above.

The B liquid added to the A liquid is diluted with water or concentrated as necessary, so that the SiO ₂ concentration is in the range of 0.5 to 10% by mass, more preferably 1 to 7% by mass. It is preferable to adjust so that. When the SiO ₂ concentration is less than 0.5% by mass, the concentration is too low, the production efficiency is low, and concentration may be required for use as a product. On the other hand, when the SiO ₂ concentration exceeds 10% by mass, the silica particles tend to aggregate, and a sol in which silica particles having a uniform particle diameter are monodispersed may not be obtained. Also, when the electrolyte or electrolyte and water are added to the B solution and then supplied to the A solution, the above range is recommended as the concentration of SiO _{2 in} the system.

供給 While supplying the B liquid to the A liquid and growing the core particles, the pH of the dispersion may be maintained in the range of 8 to 13, preferably 10 to 12, while adding an alkali or an acid if desired. As the alkali to be added, sodium hydroxide, potassium hydroxide, lithium hydroxide, aqueous ammonia, or amines such as triethylamine, triethanolamine can be used, and acids such as hydrochloric acid, nitric acid, sulfuric acid, or acetic acid can be used. Organic acids can be used.

As described above, when non-spherical seed silica fine particles are grown by adding the B liquid to the A liquid in the presence of an electrolyte composed of a strong acid salt, non-spherical silica fine particles having a plurality of hook-shaped protrusions on the surface are obtained. .

About the silica derived from B liquid, it is thought that it precipitates on the surface of a core particle, or precipitates in a system as a fine silica particle, but these all have a potential difference with a relatively big core particle, Is highly reactive. This is presumed to be a factor that causes the surface of the nuclear particle to be undulated and generate hook-shaped projections.

When the amount of electrolyte and alkali silicate used in the core particles is within the equivalent ratio range defined in the present invention, the silica concentration is high, and the smaller the particle diameter, the easier the aggregation by the electrolyte, so the low concentration Grain growth at is desirable.

In addition, when adding the B liquid and the electrolyte to the A liquid, it is preferable to add them over a temperature range of 40 to 150 ° C. over 15 minutes to 10 hours. Addition under such conditions is preferred in terms of particle stability.
After adding the aging / deionized B solution, this is aged as necessary. The aging temperature is in the range of 40 to 150 ° C., preferably 60 to 100 ° C., and the aging time is about 30 minutes to 5 hours, depending on the aging temperature. By performing such aging, a silica sol having a more uniform particle diameter and excellent stability can be obtained.

If desired, ions in the dispersion may be removed after the temperature of the dispersion is cooled to approximately 40 ° C. or lower. A conventionally known method can be adopted as a method for removing ions in the dispersion, and examples thereof include a method such as an ultrafiltration membrane method, an ion exchange resin method, and an ion exchange membrane method. In the deionization, it is preferable that the amount of remaining anions is 0.01% by mass or less, preferably 0.005% by mass or less of SiO ₂ . If the amount of residual ions is 0.01% by mass or less, although depending on the concentration described later, a silica sol having sufficient stability can be obtained, and there are no adverse effects of impurities in many applications.

The obtained silica sol is concentrated as necessary. As the concentration method, an ultrafiltration membrane method, a distillation method, or a combination thereof is usually employed, and the concentration of the silica sol after concentration is generally in the range of 1 to 50% by mass in terms of SiO ₂ . The silica sol is appropriately diluted during use or further concentrated.
[Second production method of non-spherical silica sol]
As a method for producing a non-spherical silica sol prepared using alkoxysilane as a raw material, the temperature range of a mixed solvent containing a water-soluble organic solvent and water is maintained at 30 to 150 ° C., and 1) the following general formula (1) A water-soluble organic solvent solution of a tetrafunctional silane compound represented by the formula (2) and 2) an alkali catalyst solution are added simultaneously or intermittently. After the addition is completed, the above 1) and 2) are added to the mixed solvent. The liquid obtained is further maintained in a temperature range of 30 to 150 ° C. and aged to hydrolyze and condense the tetrafunctional silane compound to produce a silica sol. A production method in which hydrolysis condensation is carried out with a water molar ratio in the range of 2 to 4 is preferably used. According to this production method, a non-spherical silica sol composed of [SiO _4/2 ] units and having non-spherical silica fine particles having a plurality of hook-shaped protrusions on the surface dispersed in a dispersion medium is obtained.

(In the formula (1), R is an alkyl group having 2 to 4 carbon atoms.)
In particular, in order to obtain non-spherical silica fine particles, an amount of water in a molar ratio of 2 to 4 with respect to the tetrafunctional silane compound in a water-soluble organic solvent / water mixed solvent at a temperature range of 30 to 150 ° C. It is necessary to hydrolyze and condense the tetrafunctional silane compound.

In the second production method, since the reaction rate of the four alkoxy groups of the tetrafunctional silane compound varies under the above conditions, the silica fine particles (primary particles) having a non-spherical distorted shape at the initial stage of hydrolysis condensation As a result of the secondary aggregation of such distorted primary particles, it is presumed that silica fine particles having ridge-like projections on the surface are generated.

When the molar ratio of water to the tetrafunctional silane compound is less than 2, the reaction does not proceed sufficiently because the four alkoxy groups of the tetrafunctional silane compound are less than the molar amount of complete hydrolysis. , Aggregation or precipitation is likely to occur during the reaction. In addition, when the molar ratio of water to the tetrafunctional silane compound is larger than 4, since the amount of water is excessive, there is no sufficient difference in the reaction rate of the alkoxy group, resulting in a spherical surface undulation. It becomes easy to produce poor silica fine particles. The range of the molar ratio of water to the tetrafunctional silane compound is preferably in the range of 2.0 to 3.8. A range of 2.0 to 3.6 is more preferable.

[Tetrafunctional silane compound]
The tetrafunctional silane compound used in the production method according to the present invention means an alkoxysilane compound represented by the following general formula (1).

(In the formula (1), R is an alkyl group having 2 to 4 carbon atoms.)
Specific examples of the tetrafunctional silane compound include tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. An alkoxysilane having 5 or more carbon atoms may not have a practical hydrolysis rate due to steric hindrance of the alkoxy group. In the case of tetramethoxysilane, the reaction rate of the hydrolysis reaction is faster than that of tetraethoxysilane, which is not desirable for practically synthesizing silica. For practical use, tetraethoxysilane is recommended.

In the production method according to the present invention, it is usually desirable to use the tetrafunctional silane compound by dissolving it in a water-soluble organic solvent. When used by dissolving in a water-soluble organic solvent, the influence of moisture in the atmosphere can be reduced. Examples of the water-soluble organic solvent for dissolving the tetrafunctional silane compound include the same water-soluble organic solvents as described below. Specifically, those having a concentration of the tetrafunctional silane compound in the water-soluble organic solvent solution of the tetrafunctional silane compound in the range of 5 to 90% by mass are preferably used. If it is less than 5% by mass, the silica concentration in the reaction solution becomes low, which is not practical. When it exceeds 90% by mass, although depending on the reaction conditions, the silica concentration in the reaction solution becomes too high and silica aggregation and precipitation are likely to occur. The concentration of the tetrafunctional silane compound is preferably in the range of 10 to 60% by mass. More preferably, the range of 20 to 40% by mass is recommended.

Note that it is preferable to use an ethanol solution of tetraethoxysilane as the water-soluble organic solvent solution of the tetrafunctional silane compound.

[Water-soluble organic solvent]
The water-soluble organic solvent used in the production method according to the present invention includes an organic solvent that dissolves the tetrafunctional silane compound represented by the general formula (1) and exhibits water solubility. Examples of such water-soluble organic solvents include ethanol, isopropanol, t-butanol and the like. About selection of a water-soluble organic solvent, what is excellent in compatibility with the tetrafunctional silane compound to be used is used suitably.

[A mixed solvent of water-soluble organic solvent and water]
Regarding the amount of water contained in the mixed solvent of the water-soluble organic solvent and water, when the alkali catalyst solution does not contain water, it is necessary that the molar ratio of water to the tetrafunctional silane compound is within the above range. It becomes. When the alkali catalyst solution contains water, the total amount of water contained in the mixed solvent and water contained in the alkali catalyst solution is the molar ratio of water to the tetrafunctional silane compound. The amount needs to be within the above range.

As the mixed solvent, those satisfying this premise are used, but preferably those having a water-soluble organic solvent concentration in the range of 30 to 95% by mass (moisture in the range of 5 to 70% by mass). . When the proportion of the water-soluble organic solvent is less than 30% by mass (moisture is 70% by mass or more), depending on the amount of the tetrafunctional silane compound and the hydrolysis rate, the added tetrafunctional silane compound and the mixed solvent are mixed. It becomes difficult and the tetrafunctional silane compound may be gelled. Moreover, when the ratio of the water-soluble organic solvent exceeds 95% by mass (moisture is less than 5% by mass), the water used for hydrolysis may be too small. The ratio of the water-soluble organic solvent in the mixed solvent of water-soluble organic solvent and water is preferably in the range of 40 to 80% by mass. More preferably, the range of 50 to 70% by mass is recommended.

[Alkali catalyst]
As the alkali catalyst used in the production method according to the present invention, basic compounds such as ammonia, amines, alkali metal hydrides, quaternary ammonium compounds and amine coupling agents are used. Although an alkali metal hydride can be used as a catalyst, it promotes hydrolysis of the alkoxy group of the alkoxysilane, and therefore, the remaining alkoxy groups (carbon) are reduced in the resulting particles and become harder. Although the polishing rate is high, scratches may occur, and when sodium hydride is used, there is a problem that the content of Na becomes high.

The amount of the alkali catalyst used is not limited as long as the desired hydrolysis rate can be obtained, but it is usually added in the range of 0.005 to 1 mol per mol of the tetrafunctional silane compound. Is preferred. More preferably, it is recommended to be added so as to be in the range of 0.01 to 0.8 mol.

The alkali catalyst is preferably diluted with water and / or a water-soluble organic solvent and used as an alkali catalyst solution. In addition, since the water contained in this water-soluble organic catalyst also contributes to hydrolysis, it is naturally included in the amount of water used for hydrolysis.

Usually, the alkali catalyst concentration in the alkali catalyst solution is preferably in the range of 0.1 to 20% by mass. If it is less than 0.1% by mass, a practical catalytic function may not be obtained. In addition, when the amount is 20% by mass or more, the catalyst function often reaches an equilibrium and may be used excessively.

The alkali catalyst concentration in the alkali catalyst solution is more preferably in the range of 1 to 15% by mass. More preferably, the range of 2 to 12% by mass is recommended.

As the alkali catalyst, for example, an aqueous ammonia solution or a mixture of an aqueous ammonium solution and ethanol can be suitably used.

[Manufacturing process]
Although the suitable manufacturing method of the silica sol which concerns on this invention is described below, the manufacturing method of the silica sol which concerns on this invention is not limited to this. The temperature range of the mixed solvent of water-soluble organic solvent and water is maintained at 30 to 150 ° C., and 1) a water-soluble organic solvent solution of a tetrafunctional silane compound and 2) an aqueous solution of an alkali catalyst are simultaneously, continuously or intermittently. For 30 minutes to 20 hours. Regarding the temperature range, if it is less than 30 ° C., hydrolysis condensation does not proceed sufficiently, which is not desirable. When it exceeds the boiling point of the mixed solvent, it can be carried out using a pressure-resistant vessel such as an autoclave. However, when it exceeds 150 ° C., a very high pressure is applied, which is not industrially desirable.

For this temperature range, a range of 40-100 ° C is recommended. More preferably, the range of 50 to 80 ° C. is recommended. With respect to the required time range for the addition, 1 to 15 hours are preferably recommended. More preferably, 2 to 10 hours are recommended.

For 1) the water-soluble organic solvent solution of the tetrafunctional silane compound and 2) the aqueous solution of the alkali catalyst, both the water-soluble organic solvent and water are used simultaneously, continuously or intermittently for 30 minutes to 20 hours. It is preferable to add to a mixed solvent. When the total amount of both is added all at once, hydrolytic condensation proceeds rapidly, resulting in the generation of a gel-like substance and silica fine particles cannot be obtained.

In the production method according to the present invention, as described above, the silica sol is prepared by utilizing the reaction rate characteristics of the tetrafunctional silane compound. For example, when tetramethoxysilane is used, it is not easy to form a silica sol like tetraethoxysilane because the hydrolysis reaction is faster than that of tetraethoxysilane.

After completion of the addition of the components necessary for the hydrolytic condensation, it is preferably aged at 30 to 150 ° C. for 0.5 to 10 hours if desired. For example, when an unreacted tetrafunctional silane compound remains, the reaction of the unreacted tetrafunctional silane compound can be promoted and completed by aging. Depending on the remaining amount of the unreacted tetrafunctional silane compound, silica may aggregate or precipitate over time. A temperature range of 40 to 100 ° C. is recommended for the temperature range during aging. More preferably, the range of 50 to 80 ° C. is recommended. The aging time range is preferably 1 to 9 hours. More preferably, 2 to 8 hours are recommended.
The obtained silica sol is concentrated as necessary. As the concentration method, an ultrafiltration membrane method, a distillation method, or a combination thereof is usually employed, and the concentration of the silica sol after concentration is generally in the range of 1 to 50% by mass in terms of SiO ₂ . The silica sol is appropriately diluted during use or further concentrated.

Organosol The non-spherical silica sol of the present invention can be produced by substituting with an organic solvent. A conventionally known method can be employed as the substitution method. When the boiling point of the organic solvent is generally higher than that of water, it can be obtained by adding an organic solvent and performing distillation. Further, when the boiling point of the organic solvent is low, it can be obtained by the ultrafiltration membrane method disclosed in Japanese Patent Application Laid-Open No. 59-8614 filed by the applicant of the present application. The concentration of the organosol obtained is in the range of 1 to 50% by weight in terms of SiO ₂ . In addition, this organosol can be used after being appropriately diluted or further concentrated.
[Abrasive and polishing composition]
The non-spherical silica sol of the present invention is useful as an abrasive and a polishing composition.

Specifically, the non-spherical silica sol of the present invention can be applied as an abrasive by itself, and can also constitute a normal polishing composition together with other components (such as a polishing accelerator). Is possible.

The polishing composition according to the present invention is obtained by dispersing the above-mentioned non-spherical silica fine particles in a solvent. As the solvent, water is usually used, but alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol can be used as necessary, and water-soluble organic solvents such as ethers, esters, and ketones are also used. be able to. The concentration of the non-spherical silica fine particles in the polishing composition is preferably in the range of 2 to 50% by weight, more preferably 5 to 30% by weight. If the concentration is less than 2% by weight, the concentration may be too low depending on the type of substrate or insulating film, resulting in a slow polishing rate and productivity. If the concentration of silica particles exceeds 50% by weight, the stability of the abrasive will be insufficient, the polishing rate and the polishing efficiency will not be further improved, and the dried product will be removed in the step of supplying the dispersion for polishing treatment. It may be generated and attached, which may cause scratches.

The polishing composition according to the present invention varies depending on the type of the material to be polished, but it may be used by adding a conventionally known hydrogen peroxide, peracetic acid, urea peroxide, or a mixture thereof as necessary. it can. When such hydrogen peroxide or the like is added and used, when the material to be polished is a metal, the polishing rate can be effectively improved. If necessary, add acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, polyphosphoric acid, amidosulfuric acid, hydrofluoric acid or the like, or add sodium salt, potassium salt, ammonium salt or a mixture thereof. Can do. In this case, when a plurality of kinds of materials to be polished are polished, a flat polishing surface can be finally obtained by increasing or decreasing the polishing rate of the material to be polished having a specific component.

イミダゾール As other additives, for example, imidazole, benzotriazole, benzothiazole and the like can be used in order to form a passive layer or a dissolution inhibiting layer on the surface of the metal polishing material to prevent erosion of the substrate. In order to disturb the passive layer, a complex forming material such as an organic acid such as citric acid, lactic acid, acetic acid, oxalic acid, phthalic acid, citric acid, or an organic acid salt thereof may be used. Other examples of the organic acid include carboxylic acid, organic phosphoric acid, and amino acid. Examples of carboxylic acids include monovalent carboxylic acids such as acetic acid, glycolic acid, and ascorbic acid, divalent carboxylic acids such as succinic acid and tartaric acid, and trivalent carboxylic acids such as citric acid. -Aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and the like. Examples of amino acids include glycine and alanine. Among these, from the viewpoint of reducing scratches, inorganic acids, carboxylic acids and organic phosphoric acids are preferable. For example, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, glycolic acid, succinic acid, citric acid, aminotri (methylenephosphonic acid) Ethylenediaminetetra (methylenephosphonic acid) and diethylenetriaminepenta (methylenephosphonic acid) are suitable. These acids can be used as an acid for adjusting the pH.

カチオン Cationic, anionic, nonionic, and amphoteric surfactants can be appropriately selected and added to improve the dispersibility and stability of the abrasive slurry. Furthermore, the pH of the abrasive slurry can be adjusted by adding an acid or a base as necessary in order to enhance the effect of each additive.

Preferred embodiment 1
Non-spherical shape in which the average particle size measured by the dynamic light scattering method is in the range of 3 to 200 nm, the minor axis / major axis ratio is in the range of 0.01 to 0.8, and the specific surface area is in the range of 10 to 800 m ² / g. In a non-spherical silica sol in which silica fine particles are dispersed in a dispersion medium, the non-spherical silica fine particles have a plurality of hook-shaped projections on the surface, and the non-spherical silica fine particles are arranged on the plane including the major axis of the non-spherical silica fine particles. The distance from an arbitrary point on the outer edge of the spherical silica fine particle to the intersection B of the straight line passing through the point on the outer edge and perpendicular to the long axis and the long axis is Y, the outer edge of the non-spherical silica fine particle and the length A non-spherical silica sol characterized in that when an XY curve is drawn with a distance from one intersection A to the axis to the intersection B as X, the XY curve has a plurality of maximum values.

Preferred embodiment 2
Non-spherical shape in which the average particle size measured by the dynamic light scattering method is in the range of 3 to 200 nm, the minor axis / major axis ratio is in the range of 0.01 to 0.8, and the specific surface area is in the range of 10 to 800 m ² / g. In a non-spherical silica sol in which silica fine particles are dispersed in a dispersion medium, the non-spherical silica fine particles have a plurality of hook-shaped protrusions on the surface, and the non-spherical silica sol is formed on a plane including the major axis of the non-spherical silica fine particles. Y is the distance from an arbitrary point on the outer edge of the silica fine particle to the intersection B of the straight line passing through the point on the outer edge and perpendicular to the major axis, and the outer edge of the non-spherical silica fine particle and the major axis And when the XY curve is drawn with the distance from one intersection A to the intersection B as X, the XY curve has a plurality of maximum values, and the non-spherical silica fine particles On a plane including the major axis of When the distance from an arbitrary point on the outer edge of the spherical silica fine particle to an intersection B between the long axis passing through the point on the outer edge and the long axis is Y, the variation coefficient of Y is A non-spherical silica sol characterized by being in the range of 5 to 50%.

Preferred embodiment 3
Non-spherical shape in which the average particle size measured by the dynamic light scattering method is in the range of 3 to 200 nm, the minor axis / major axis ratio is in the range of 0.01 to 0.8, and the specific surface area is in the range of 10 to 800 m ² / g. In a non-spherical silica sol in which silica fine particles are dispersed in a dispersion medium, the non-spherical silica fine particles have a plurality of hook-shaped projections on the surface, and the non-spherical silica fine particles are arranged on the plane including the major axis of the non-spherical silica fine particles. The distance from an arbitrary point on the outer edge of the spherical silica fine particle to the intersection B of the straight line passing through the point on the outer edge and perpendicular to the long axis and the long axis is Y, the outer edge of the non-spherical silica fine particle and the length Including a non-spherical silica sol characterized in that when an XY curve is drawn with a distance from one intersection A with the axis to the intersection B as X, the XY curve has a plurality of maximum values Polishing composition.

Preferred embodiment 4
Non-spherical shape in which the average particle size measured by the dynamic light scattering method is in the range of 3 to 200 nm, the minor axis / major axis ratio is in the range of 0.01 to 0.8, and the specific surface area is in the range of 10 to 800 m ² / g. In a non-spherical silica sol in which silica fine particles are dispersed in a dispersion medium, the non-spherical silica fine particles have a plurality of hook-shaped protrusions on the surface, and the non-spherical silica sol is formed on a plane including the major axis of the non-spherical silica fine particles. Y is the distance from an arbitrary point on the outer edge of the silica fine particle to the intersection B of the straight line passing through the point on the outer edge and perpendicular to the major axis, and the outer edge of the non-spherical silica fine particle and the major axis And when the XY curve is drawn with the distance from one intersection A to the intersection B as X, the XY curve has a plurality of maximum values, and the non-spherical silica fine particles On a plane including the major axis of When the distance from an arbitrary point on the outer edge of the spherical silica fine particle to an intersection B between the long axis passing through the point on the outer edge and the long axis is Y, the variation coefficient of Y is A polishing composition comprising a non-spherical silica sol characterized by being in the range of 5 to 50%.

Preferred embodiment 5
Non-spherical shape in which the average particle size measured by the dynamic light scattering method is in the range of 3 to 200 nm, the minor axis / major axis ratio is in the range of 0.01 to 0.8, and the specific surface area is in the range of 10 to 800 m ² / g. In a non-spherical silica sol in which silica fine particles are dispersed in a dispersion medium, a point on the outer edge of the non-spherical silica fine particle passes through a point on the outer edge on a plane including the long axis of the non-spherical silica fine particle. The distance from the straight line perpendicular to the major axis to the intersection B of the major axis is Y, and the distance from one intersection A of the outer edge of the non-spherical silica fine particle to the major axis is X, X When a -Y curve is drawn, the XY curve has a plurality of maximum values, and further on the outer edge of the non-spherical silica fine particle on a plane including the major axis of the non-spherical silica fine particle. From any point, passing through a point on the outer edge The distance between a straight line perpendicular to the major axis to the intersection point B of the major axis when the Y, non-spherical silica sol, wherein the variation coefficient of the Y is in the range of 5-50%.

Preferred embodiment 6
Non-spherical shape in which the average particle size measured by the dynamic light scattering method is in the range of 3 to 200 nm, the minor axis / major axis ratio is in the range of 0.01 to 0.8, and the specific surface area is in the range of 10 to 800 m ² / g. In a non-spherical silica sol in which silica fine particles are dispersed in a dispersion medium, a point on the outer edge of the non-spherical silica fine particle passes through a point on the outer edge on a plane including the long axis of the non-spherical silica fine particle. The distance from the straight line perpendicular to the major axis to the intersection B of the major axis is Y, and the distance from one intersection A of the outer edge of the non-spherical silica fine particle to the major axis is X, X When a -Y curve is drawn, the XY curve has a plurality of maximum values, and further on the outer edge of the non-spherical silica fine particle on a plane including the major axis of the non-spherical silica fine particle. From any point, passing through a point on the outer edge A non-spherical silica sol characterized in that the coefficient of variation of Y is in the range of 5 to 50%, where Y is the distance to the intersection B between the straight line perpendicular to the long axis and the long axis, The non-spherical silica fine particles are made of polysiloxane composed of [SiO _4/2 ] units obtained by hydrolysis of tetraethoxysilane, and the sodium content is 100 mass ppm or less. Spherical silica sol.

[Analysis methods used in Examples and Comparative Examples]
[1] Method for Measuring Average Particle Diameter (D1) by Dynamic Light Scattering Method Regarding the average particle diameter measured by the dynamic light scattering method, a particle size distribution measuring device (Particle) is obtained by a dynamic light scattering method using laser light. The average particle size was measured by using a NICOMP MODEL 380 (manufactured by Sizing Systems).
[2] Method for measuring the maximum number of distances Y from the outer edge of the particle to the long axis The length of the non-spherical silica fine particles in the image of a scanning electron micrograph (250,000 to 500,000 times) of the non-spherical silica fine particles Set the axis, divide the entire length of the major axis into 40 equal parts, and draw the distance between each point (point B) for the time being and the point intersecting the outer edge of the fine particle by extending a straight line perpendicular to that point to one side of the fine particle Record as Y. Further, let X be the length of one point (point A) of the two intersections between the outer edge of the non-spherical silica fine particle and the long axis, and the corresponding point (point B). By plotting the Y value corresponding to each X with Y as the vertical axis and X as the horizontal axis, the XY curve can be drawn, and the number of local maximum values of this XY curve can be measured.

In the present application, such a measurement was performed for 50 particles of non-spherical silica fine particles, and the average of the number of local maximum values was taken as the maximum number of distances Y from the outer edge of the particle to the major axis.
[3] Method for calculating the coefficient of variation (CV value) of the distance Y from the outer edge of the particle to the long axis The measurement of the coefficient of variation of the distance Y from the outer edge of the fine particle to the long axis in the present invention is calculated by the following method. did.
1) The distance from the center point of the major axis to the outer edge of one fine particle (major axis radius M) was measured and plotted on the major axis from 0 to 50% in 5% increments from the center point to the major axis radius M.
2) A straight line perpendicular to the major axis was drawn in each plot, and the distance Y from the point where the straight line intersected the outer edge of the fine particle on one side to the plot was measured.
3) Regarding the coefficient of variation (CV value) for the distance Y from the outer edge of the fine particle to the long axis, on the long axis, the range from 0 to 10% of the long axis radius M from the center point is 0 to 20%. Calculate each coefficient of variation (CV value) in the range, 0-30% range, 0-40% range, 0-50% range to obtain 5 types of variation coefficients (CV value), of which The maximum coefficient of variation (CV value) was defined as the coefficient of variation (CV value) for the distance Y in the particle.
4) The above measurements 1) to 3) were performed on 50 particles, and the average value was adopted as the coefficient of variation (CV value) for the distance Y in the non-spherical silica fine particles.
[4] Specific surface area measurement and average particle diameter measurement by Sears method 1) A sample corresponding to 15 g as SiO ₂ was collected in a beaker, transferred to a constant temperature reaction tank (25 ° C.), and pure water was added to adjust the liquid volume. 90 ml. (The following operations were performed in a constant temperature reaction tank maintained at 25 ° C.)
2) 0.1 mol / L hydrochloric acid aqueous solution was added so that pH might be 3.6.
3) 30 g of sodium chloride was added, diluted to 150 ml with pure water, and stirred for 10 minutes.
4) A pH electrode was set, and a 0.1 mol / L sodium hydroxide solution was added dropwise with stirring to adjust the pH to 4.0.
5) Titrate the sample adjusted to pH 4.0 with 0.1 mol / L sodium hydroxide solution, record titration amount in the range of pH 8.7 to 9.3 and 4 or more pH values. A calibration curve was prepared with X as the titer of 1 mol / L sodium hydroxide solution and Y as the pH value at that time.
6) The consumption amount V (ml) of 0.1 mol / L sodium hydroxide solution required for pH 4.0 to 9.0 per 15 g of SiO ₂ is obtained from the following formula (2), and the following formula (3) is obtained. The specific surface area SA [m ² / g] was determined.

Further, the average particle diameter D1 (nm) was obtained from the formula (4).

V = (A × f × 100 × 15) / (W × C) (2)
SA = 29.0V-28 (3)
D1 = 6000 / (ρ × SA) (4)
(Here, ρ represents the density (g / cm ³ ) of particles. In the case of silica, 2.2 is substituted.)
However, the meanings of the symbols in the above formula (2) are as follows.
A: Titration of 0.1 mol / L sodium hydroxide solution required for pH 4.0 to 9.0 per 15 g of SiO ₂ (ml)
f: Potency of 0.1 mol / L sodium hydroxide solution C: SiO ₂ concentration of sample (%)
W: Sampling amount (g)
[5] Specific surface area measurement by BET method (nitrogen adsorption method) A sample obtained by adjusting 50 ml of non-spherical silica sol to pH 3.5 with HNO ₃ , adding 40 ml of 1-propanol, and drying at 110 ° C. for 16 hours is crushed in a mortar. The sample for measurement was baked at 500 ° C. for 1 hour in a muffle furnace. And the specific surface area was computed by the BET 1 point method from the adsorption amount of nitrogen using the nitrogen adsorption method (BET method) using the specific surface area measuring apparatus (The product made from Yuasa Ionics, model number multisorb 12). Specifically, 0.5 g of a sample is taken in a measurement cell, degassed for 20 minutes at 300 ° C. in a mixed gas stream of nitrogen 30 v% / helium 70 v%, and then the sample is liquidized in the mixed gas stream. The nitrogen temperature was maintained and nitrogen was adsorbed on the sample by equilibrium. Next, the sample temperature was gradually raised to room temperature while flowing the above mixed gas, the amount of nitrogen desorbed during that time was detected, and the specific surface area of the non-spherical silica sol was calculated using a calibration curve prepared in advance. Further, the obtained specific surface area (SA) was substituted into the formula (4) to determine the average particle diameter D1.
[6] Measuring method of ratio of minor axis / major axis Obtained by photographing a sample non-spherical silica sol at a magnification of 250,000 times (or 500,000 times) with a scanning electron microscope (H-800, manufactured by Hitachi, Ltd.) In the photograph projection view, the maximum diameter of the particles was taken as the major axis, the length was measured, and the value was taken as the major diameter (DL). Further, a point that bisects the major axis on the major axis was determined, two points where a straight line perpendicular to the major axis intersected with the outer edge of the particle were determined, and a distance between the two points was measured to obtain a minor axis (DS). And ratio (DS / DL) was calculated | required. This measurement was performed on any 50 particles, and the average value was defined as the minor axis / major axis ratio. When a plurality of major axes can be set for one particle, an average value of a plurality of corresponding minor axis lengths was obtained and used as the minor axis length (DS).
[7] Measurement of ratio of non-spherical silica fine particles Among the 50 particles whose short diameter / long diameter ratio were measured in “[6] Measuring method of short diameter / long diameter ratio”, particles corresponding to the following (i) And the total number (n) of the particles corresponding to (ii) is measured, and the value of [(50−n) / 50] × 100 is determined as the number of non-protruding protrusions with respect to the number of all silica fine particles as a dispersoid. The ratio (%) was the number of spherical silica fine particles.
(I) Particles whose minor axis / major axis ratio is out of the range of 0.01 to 0.8 (ii) The minor axis / major axis ratio is in the range of 0.01 to 0.8 and has hook-shaped protrusions. Particle [8] Evaluation Method for Polishing Characteristics for Aluminum Substrate
Preparation of polishing slurry Sample silica sol was adjusted to a silica concentration of 20% by mass, H ₂ O ₂ , HEDP (1-hydroxyethylidene-1,1-disulfonic acid) and ultrapure water were added to obtain 9% silica by weight, H ₂₎ A polishing slurry of 0.5% by weight of O _{2 and} 0.5% by weight of 1-hydroxyethylidene-1,1-disulfonic acid was prepared. Further, HNO ₃ was added as necessary to prepare a polishing slurry having a pH of 2. Prepared.
Polishing substrate An aluminum disk substrate was used as the polishing substrate. This aluminum disk substrate is a substrate (95 mmΦ / 25 mmΦ-1.27 mmt) in which Ni—P is electrolessly plated (a hard Ni—P plating layer having a composition of Ni 88% and P12%) on an aluminum substrate. It was used. This substrate was first polished and the surface roughness (Ra) was 0.17 nm.
Polishing test The above substrate to be polished is set in a polishing apparatus (manufactured by Nano Factor Co., Ltd .: NF300), and a polishing pad (“Apollon” manufactured by Rodel) is used and polished at a substrate load of 0.05 MPa and a table rotation speed of 30 rpm. Polishing was performed by supplying the slurry for 5 minutes at a rate of 20 g / min.

The change in weight of the substrate to be polished before and after polishing was determined to calculate the polishing rate [nm / min].
Measurement of scratches (line marks) Regarding the occurrence of scratches, after polishing a substrate for an aluminum disk in the same manner as described above, an ultra-fine defect / visualization macro device (product name: Micro-MAX, manufactured by VISION PSYTEC) was used. The entire surface was observed with a Zoom 15, and the number of scratches (linear traces) on the polished substrate surface corresponding to 65.97 cm ² was counted and totaled.
[9] Evaluation method of polishing characteristics for glass substrate
Preparation of Polishing Slurry The sample silica sol was adjusted to a silica concentration of 20% by mass, and ultrapure water and a 5% by mass aqueous sodium hydroxide solution were added to prepare a polishing slurry of 9% silica by weight and pH 10.5.
Polished substrate A glass substrate for hard disk made of 65 mmφ tempered glass was used as the substrate to be polished. This glass substrate for hard disk has been subjected to primary polishing and has a maximum surface roughness of 0.21 μm.
Polishing test The above substrate to be polished was set in a polishing apparatus (manufactured by Nano Factor Co., Ltd .: NF300), and a polishing pad (“Apollon” manufactured by Rodel) was used and polished at a substrate load of 0.18 MPa and a table rotation speed of 30 rpm. Polishing was performed by supplying the slurry for 10 minutes at a rate of 20 g / min.

The change in weight of the substrate to be polished before and after polishing was determined to calculate the polishing rate [nm / min].
Measurement of scratches (line marks) Regarding the occurrence of scratches, after polishing the glass substrate in the same manner as described above, an ultra-fine defect / visualization macro device (product name: Micro-MAX, manufactured by VISION PSYTEC) was used. The entire surface was observed with Zoom ^1, and the number of scratches (linear traces) on the polished substrate surface corresponding to 65.97 cm ² was counted and totaled.
[10] Evaluation method of polishing characteristics for thermal oxide film
Preparation of Polishing Slurry KOH was added to silica sol having a silica concentration of 12.6% by mass obtained in each Example and each Comparative Example, and the pH was adjusted to 10.
Polished substrate
As the substrate to be polished, a thermal oxide film substrate obtained by wet-oxidizing a silicon wafer at 1050 ° C. was used.
Polishing test The substrate to be polished was set in a polishing apparatus (manufactured by Nano Factor Co., Ltd .: NF330), a polishing pad (“IC-1000” manufactured by Rodel) was used, the substrate load was 0.05 MPa, and the table rotation speed was 30 rpm. Polishing was performed by supplying a polishing slurry for polishing at a rate of 20 g / min for 5 minutes. The film thickness before and after polishing was measured with a short wavelength ellipsometer, and the polishing rate was calculated.

[11] Sodium determination method The sodium content was measured by the following procedure.
1) About 10 g of sample silica sol was collected in a platinum dish and weighed to 0.1 mg.
2) 5 ml of nitric acid and 20 ml of hydrofluoric acid were added, heated on a sand bath, and evaporated to dryness.
3) When the amount of liquid decreased, 20 ml of hydrofluoric acid was further added and heated on a sand bath to evaporate to dryness.
4) After cooling to room temperature, 2 ml of nitric acid and about 50 ml of water were added and dissolved by heating on a sand bath.
5) After cooling to room temperature, it was put into a flask (100 ml) and diluted to 100 ml with water to obtain a sample solution.
6) Atomic absorption spectrophotometer (manufactured by Hitachi, Ltd., Z-5300, measurement mode: atomic absorption, measurement wavelength: 190 to 900 nm, Na detection wavelength in the case of silica sample is 589.0 nm), sample solution The content of sodium metal present therein was measured. This atomic absorption spectrophotometer vaporizes a sample with a frame, irradiates the atomic vapor layer with light of an appropriate wavelength, and measures the intensity of light absorbed by the atoms at that time. The elemental concentration of was quantified.
7) 2 ml of 50% sulfuric acid aqueous solution was added to 10 g of sample silica sol and evaporated to dryness on a platinum pan. The obtained solid was fired at 1000 ° C. for 1 hour, cooled and weighed. Next, dissolve the weighed solid in a small amount of 50% aqueous sulfuric acid, add 20 ml of hydrofluoric acid, evaporate to dryness on a platinum pan, bake at 1000 ° C. for 15 minutes, and cool. Weighed. The silica content was determined from these weight differences.
8) The ratio of Na to SiO ₂ was calculated from the results of 6) and 7) above.

[Synthesis Example 1]
18.7 g of a sodium silicate aqueous solution (SiO ₂ / Na ₂ O molar ratio 3) having a SiO ₂ concentration of 24 wt% was placed in a separable flask equipped with a reflux condenser and a stirrer, and 837 g of water was further added to prepare 855 g of an aqueous sodium silicate solution. . Next, sodium silicate (SiO ₂ / Na ₂ O molar ratio: 3) having a SiO ₂ concentration of 4.82% by weight was passed through the cation exchange resin tower through this sodium silicate aqueous solution to obtain a SiO ₂ concentration of 4.82. By adding 1,067 g of a weight percent silicic acid solution (pH 2.3, SiO ₂ / Na ₂ O molar ratio = 1200), a mixed liquid consisting of a silicic acid solution and an aqueous sodium silicate solution (SiO ₂ / Na ₂ O molar ratio 35) Got.

The resulting liquid was heated and aged at 98 ° C. for 30 minutes. Thereafter, 1,162 g of a silicic acid solution having the same composition as that of the silicic acid solution was added to this solution over a period of 4 hours, and a non-spherical silica sol having a pH of 8.9 was obtained. This non-spherical silica sol had a SiO ₂ / Na ₂ O molar ratio of 76.

After adding 2.5% sulfuric acid aqueous solution so that the pH of this non-spherical silica sol becomes 8.5 and heating at 90 ° C. for 8 hours, it is concentrated with an evaporator until the SiO ₂ concentration becomes 20% by weight. A non-spherical silica sol was prepared.

The average particle size calculated from the specific surface area measured by the BET method for the non-spherical silica fine particles contained in this non-spherical silica sol was 12 nm, and the average particle size by the dynamic light scattering method was 34 nm. Further, the minor diameter / major diameter ratio of the non-spherical silica fine particles was 0.45, and the specific surface area was 220 m ² / g.
[Synthesis Example 2]
With respect to 100 g of silica sol (average particle diameter measured by BET method: 35 nm, specific surface area: 182 m ² / g, SiO ₂ concentration: 30 wt%), a strongly acidic cation exchange resin SK1BH until pH becomes 2.3 (Mitsubishi Chemical Co., Ltd.) 0.4 L was repeatedly passed at a space velocity of 3.1. Next, a strong basic ion exchange resin SANUPC (manufactured by Mitsubishi Chemical Corporation) was passed through 0.4 L at a space velocity of 3.1 to adjust the pH to 5.6, and then an alkaline aqueous solution so that the pH became 7.8. As a result, 5.4 g of a 5% aqueous ammonia solution was added. And it heated at 90 degreeC for 30 hours. This non-spherical silica sol was concentrated with an evaporator until the SiO ₂ concentration became 20% by weight to prepare a non-spherical silica sol.

The average particle size of this non-spherical silica sol measured by the BET method was 35 nm, and the average particle size by the dynamic light scattering method was 70 nm. Further, the non-spherical silica sol had a minor axis / major axis ratio of 0.4 and a specific surface area of 180 m ² / g.
[Synthesis Example 3]
A sodium silicate aqueous solution (SiO ₂ / Na ₂ O molar ratio: 3.1) having a SiO ₂ concentration of 24% by weight was diluted with ion-exchanged water, and a sodium silicate aqueous solution (pH 11.3) having a SiO ₂ concentration of 5% by weight. 1 kg was prepared.

Sulfuric acid was added to neutralize this sodium silicate aqueous solution so that the pH was 6.5, and the mixture was kept at room temperature for 1 hour to prepare a silica hydrogel. This silica hydrogel was thoroughly washed with an Oliver filter with a 28% aqueous ammonia solution (corresponding to about 120 times the SiO ₂ solid content) to remove salts. The sodium sulfate concentration after washing was less than 0.01% based on the SiO ₂ solid content.

The obtained silica hydrogel was dispersed in pure water (silica concentration: 3% by weight) to prepare a silica hydrogel dispersion in a fluid slurry state with a strong stirrer. This was added to a 5% by weight NaOH aqueous solution and 28% ammonia. A 1: 1 mixture of water was added so that the SiO ₂ / Na ₂ O molar ratio was 75 and heated at 160 ° C. for 1 hour.

Next, 0.81 kg of 24% sodium silicate and 10.93 kg of pure water were added to 2.09 kg of the above non-spherical silica sol to prepare 13.83 kg (pH 11.2) of seed sol. The average particle size of the seed sol measured by the dynamic light scattering method was 17 nm.

Next, while maintaining the seed sol at 90 ° C., 117.2 kg of a silicic acid solution having a SiO ₂ concentration of 4.5% by weight described later was added thereto over 10 hours. After completion of the addition, the mixture was cooled to room temperature, and the obtained non-spherical silica sol was concentrated with an ultrafiltration membrane until the SiO ₂ concentration became 20% by weight.

The average particle diameter of this non-spherical silica sol measured by the BET method was 50 nm, and the average particle diameter by the dynamic light scattering method was 100 nm. Further, the non-spherical silica sol had a minor axis / major axis ratio of 0.3 and a specific surface area of 50 m ² / g.
[Synthesis Example 4]
18.7 g of a sodium silicate aqueous solution (SiO ₂ / Na ₂ O molar ratio 3) having a SiO ₂ concentration of 24% by weight and a Na ₂ O concentration of 8.16% by weight is placed in a separable flask equipped with a reflux and a stirrer. 895 g of water was added to prepare 914 g of an aqueous sodium silicate solution.

Next, sodium silicate (SiO ₂ / Na ₂ O molar ratio: 3) having a SiO ₂ concentration of 4.82% by weight was passed through the cation exchange resin tower through this sodium silicate aqueous solution to obtain a SiO ₂ concentration of 4.82. By adding 1,900 g of a weight percent silicic acid solution (pH 2.3, SiO ₂ / Na ₂ O molar ratio = 1,200) under a temperature condition of 35 ° C., a mixed solution comprising a silicic acid solution and an aqueous sodium silicate solution (SiO ₂ / Na ₂ O molar ratio 60) was obtained.

The resulting mixture was warmed and aged at 80 ° C. for 30 minutes. While maintaining the temperature at 80 ° C., 329 g of a silicic acid solution having the same composition as that of the silicic acid solution was added to this solution over 2 hours to obtain a non-spherical silica sol having a pH of 8.7. The non-spherical silica sol had a SiO ₂ / Na ₂ O molar ratio of 76.

This non-spherical silica sol was heated at 70 ° C. for 12 hours, and then concentrated by an evaporator until the SiO ₂ concentration became 20% by weight. The average particle diameter of this non-spherical silica sol converted from the specific surface area measured by the BET method was 6 nm, and the average particle diameter by the dynamic light scattering method was 12 nm. Further, the value of the ratio of minor axis / major axis was 0.15, and the specific surface area was 455 m ² / g.

The following examples all satisfy the conditions of the claims of the present application.

[Example 1]
Preparation of core particle dispersion Non-spherical silica sol prepared by the same method as in Synthesis Example 1 (average particle diameter measured by dynamic light scattering method 24 nm, minor diameter / major diameter ratio 0.45, SiO ₂ concentration 20 mass%) Was diluted with pure water to 4170 g (SiO ₂ concentration 1% by mass), and a 5% by mass sodium hydroxide aqueous solution was added so that the silica sol had a pH of 11. Next, the temperature of the silica sol was raised to 80 ° C. and maintained at 80 ° C. for 30 minutes to obtain a core particle dispersion (liquid A).
575 g of core particle growth water glass (manufactured by Dokai Chemical Co., Ltd .: JIS No. 3 water glass, SiO ₂ concentration 24 mass%) was diluted with 2185 g of water to prepare 2760 g of an aqueous alkali silicate solution (liquid B). Moreover, 2352 g of water was added to 98.0 g of ammonium sulfate (made by Mitsubishi Chemical Corporation) as an electrolyte to prepare 2450 g of an aqueous electrolyte solution. Then, with respect to the total amount of the core particle dispersion (liquid A) maintained at 80 ° C., the alkali silicate aqueous solution (liquid B) and the electrolyte aqueous solution are each added at 80 ° C. over 1 hour. The particle growth was carried out.

Here, the equivalent ratio EA / EE of the alkali of B liquid and electrolyte was 1.0. Next, after aging at 80 ° C. for 1 hour, washing was performed with an ultrafiltration membrane until the pH of the core particle dispersion liquid with the grown particles reached 9.1. Subsequently, concentration was performed to obtain a non-spherical silica sol having a SiO ₂ concentration of 20% by mass. The characteristics of the obtained non-spherical silica sol are shown in Table 3. In addition, Table 3 shows the evaluation results of this non-spherical silica sol according to the above-mentioned [8] Evaluation method of polishing characteristics for aluminum substrate. (Hereinafter, the evaluation results of Examples 2 and 3 and Comparative Examples 1 and 2 according to [8] Evaluation Method of Polishing Properties for Aluminum Substrate are also shown in Table 3.) Tables 1 and 2 show.
[Example 2]
Preparation of core particle dispersion Non-spherical silica sol prepared by the same method as in Synthesis Example 4 (average particle diameter 12 nm, minor diameter / major diameter ratio 0.15, SiO ₂ concentration 20 mass% measured by dynamic light scattering method) Was diluted with pure water to 4170 g (SiO ₂ concentration: 1% by mass), and a 5% by mass sodium hydroxide aqueous solution was added so that the silica sol had a pH of 11. Next, the temperature of the silica sol was raised to 65 ° C. and maintained at 65 ° C. for 30 minutes to obtain a core particle dispersion (liquid A).
575 g of core particle growth water glass (manufactured by Dokai Chemical Co., Ltd .: JIS No. 3 water glass, SiO ₂ concentration 24 mass%) was diluted with 2185 g of water to prepare 2760 g of an aqueous alkali silicate solution (liquid B). Moreover, 2352 g of water was added to 98.0 g of ammonium sulfate (made by Mitsubishi Chemical Corporation) as an electrolyte to prepare 2450 g of an aqueous electrolyte solution. Then, with respect to the total amount of the core particle dispersion (liquid A) maintained at 65 ° C., the alkali silicate aqueous solution (liquid B) and the electrolyte aqueous solution are respectively added at 65 ° C. over 1 hour. The particle growth was carried out. Here, the equivalent ratio EA / EE of the alkali of B liquid and electrolyte was 1.0. Subsequently, after aging at 65 ° C. for 1 hour, washing was performed with an ultrafiltration membrane until the pH of the core particle dispersion with the grown particles reached 9.4. Subsequently, concentration was performed to obtain a non-spherical silica sol having a SiO ₂ concentration of 20% by mass. The characteristics of the obtained non-spherical silica sol are shown in Table 3. The production conditions for the non-spherical silica sol are shown in Tables 1 and 2.
[Example 3]
Preparation of core particle dispersion Non-spherical silica sol prepared by the same method as in Synthesis Example 2 (average particle diameter 70 nm, minor diameter / major diameter ratio 0.4, SiO ₂ concentration 20 mass% measured by dynamic light scattering method) Was diluted with pure water to 4170 g (SiO ₂ concentration 1% by mass), and a 5% by mass sodium hydroxide aqueous solution was added so that the silica sol had a pH of 11. Next, the temperature of the silica sol was raised to 95 ° C. and maintained at 95 ° C. for 30 minutes to obtain a core particle dispersion (liquid A).
575 g of core particle growth water glass (manufactured by Dokai Chemical Co., Ltd .: JIS No. 3 water glass, SiO ₂ concentration 24 mass%) was diluted with 2185 g of water to prepare 2760 g of an aqueous alkali silicate solution (liquid B). Moreover, 2376 g of water was added to 74.2 g of ammonium nitrate (manufactured by Mitsubishi Chemical Corporation) as an electrolyte to prepare 2450.2 g of an aqueous electrolyte solution. Then, the total amount of the alkali silicate aqueous solution (liquid B) and the electrolyte aqueous solution are respectively added at 95 ° C. over 1 hour with respect to the total amount of the core particle dispersion (liquid A) maintained at 95 ° C. The particle growth was carried out.

Here, the equivalent ratio of the alkali of B liquid to the electrolyte EA / EE Was 0.8. Next, after aging at 95 ° C. for 1 hour, washing was performed with an ultrafiltration membrane until the pH of the particle-grown core particle dispersion reached 10. Subsequently, concentration was performed to obtain a non-spherical silica sol having a SiO ₂ concentration of 20% by mass. The characteristics of the obtained non-spherical silica sol are shown in Table 3. Moreover, the scanning electron micrograph (magnification 250,000 times) of the obtained non-spherical silica sol is shown in FIG. The production conditions for the non-spherical silica sol are shown in Tables 1 and 2.
[Example 4]
Preparation of core particle dispersion Non-spherical silica sol prepared by the same method as in Synthesis Example 3 (average particle diameter 100 nm, minor diameter / major diameter ratio 0.30, SiO ₂ concentration 20 mass% measured by dynamic light scattering method) Was diluted with pure water to 3890 g (SiO ₂ concentration 1 mass%), and a 5 mass% sodium hydroxide aqueous solution was added so that the silica sol had a pH of 11. Next, the temperature of the silica sol was raised to 80 ° C. and maintained at 80 ° C. for 30 minutes to obtain a core particle dispersion (liquid A).
588 g of core particle growth water glass (manufactured by Dokai Chemical Co., Ltd .: JIS No. 3 water glass, SiO ₂ concentration 24 mass%) was diluted with 2232 g of water to prepare 2820 g of an aqueous alkali silicate solution (B liquid). Moreover, 2412 g of water was added to 93.3 g of ammonium nitrate (manufactured by Mitsubishi Chemical Corporation) as an electrolyte to prepare 2505.3 g of an aqueous electrolyte solution. Then, with respect to the total amount of the core particle dispersion (liquid A) maintained at 80 ° C., the alkali silicate aqueous solution (liquid B) and the electrolyte aqueous solution are each added at 80 ° C. over 1 hour. The particle growth was carried out.

Here, the equivalent ratio EA between the alkali of B liquid and the electrolyte / EE was 0.65. Then, after aging at 80 ° C. for 1 hour, washing was performed with an ultrafiltration membrane until the pH reached 9.8. Subsequently, concentration was performed to obtain a non-spherical silica sol having a SiO ₂ concentration of 20% by mass. The characteristics of the obtained non-spherical silica sol are shown in Table 3.

Further, Table 3 shows the results of evaluating the polishing characteristics of the obtained non-spherical silica sol by the above-mentioned [9] Evaluation method of polishing characteristics for glass substrate. (Hereinafter, the evaluation results for Example 5 in the same manner as described in [9] Evaluation Method for Polishing Properties of Glass Substrate are shown in Table 1.) The production conditions for the non-spherical silica sol are shown in Tables 1 and 2.
[Example 5]
Preparation of core particle dispersion Non-spherical silica sol prepared by the same method as in Synthesis Example 3 (average particle diameter 100 nm, minor diameter / major diameter ratio 0.30, SiO ₂ concentration 20 mass% measured by dynamic light scattering method) Was diluted with pure water to 3890 g (SiO ₂ concentration 1 mass%), and a 5 mass% sodium hydroxide aqueous solution was added so that the silica sol had a pH of 11. Next, the temperature of the silica sol was raised to 80 ° C. and maintained at 80 ° C. for 30 minutes to obtain a core particle dispersion (liquid A).
588 g of core particle growth water glass (manufactured by Dokai Chemical Co., Ltd .: JIS No. 3 water glass, SiO ₂ concentration 24 mass%) was diluted with 2232 g of water to prepare 2820 g of an aqueous alkali silicate solution (B liquid). Moreover, 2405 g of water was added to 100.2 g of ammonium sulfate (manufactured by Mitsubishi Chemical Corporation) as an electrolyte to prepare 2505.2 g of an aqueous electrolyte solution. Then, with respect to the total amount of the core particle dispersion (liquid A) maintained at 80 ° C., the alkali silicate aqueous solution (liquid B) and the electrolyte aqueous solution are each added at 80 ° C. over 1 hour. The particle growth was carried out.

Here, the equivalent ratio of the alkali of B liquid to the electrolyte EA / EE Was 1.0. Next, after aging at 80 ° C. for 1 hour, washing was performed with an ultrafiltration membrane until the pH reached 9.2. Subsequently, concentration was performed to obtain a non-spherical silica sol having a SiO ₂ concentration of 20% by mass. The characteristics of the obtained non-spherical silica sol are shown in Table 3. The production conditions for the non-spherical silica sol are shown in Tables 1 and 2.
[Comparative Example 1]
Preparation of core particle dispersion Non-spherical silica sol prepared by the same method as in Synthesis Example 1 (average particle diameter measured by dynamic light scattering method 24 nm, minor diameter / major diameter ratio 0.45, SiO ₂ concentration 20 mass%) Was diluted with pure water to 730 g (SiO ₂ concentration 1% by mass), and a 5% by mass sodium hydroxide aqueous solution was added so that the silica sol had a pH of 11. Next, the temperature of the silica sol was raised to 95 ° C. and maintained at 95 ° C. for 30 minutes to obtain a core particle dispersion (liquid A).
Growing water glass of core particles (manufactured by Dokai Chemical Co., Ltd .: JIS No. 3 water glass, SiO ₂ concentration 24 mass%) 888 g was diluted with 4400 g of water to prepare 5288 g of an alkali silicate aqueous solution (liquid B). Moreover, 4800 g of water was added to 151.3 g of ammonium sulfate (manufactured by Mitsubishi Chemical Corporation) as an electrolyte to prepare 4951.3 g of an aqueous electrolyte solution. Then, with respect to the total amount of the core particle dispersion (liquid A) maintained at 95 ° C., the alkali silicate aqueous solution (liquid B) and the electrolyte aqueous solution are respectively added at 95 ° C. over 9 hours. The particle growth was carried out.

Here, the equivalent ratio EA / EE of the alkali of B liquid and electrolyte was 1.0. Next, after aging at 95 ° C. for 1 hour, washing was performed with an ultrafiltration membrane until the pH reached 9.8. Subsequently, concentration was performed to obtain a non-spherical silica sol having a SiO ₂ concentration of 20% by mass. The characteristics of the obtained non-spherical silica sol are shown in Table 3. In Comparative Example 1, the specific surface area of the silica sol was measured by a nitrogen adsorption method.
[Comparative Example 2]
Pure water was added to silica sol (catalyst chemical industry Co., Ltd .: Cataloid SI-40, average particle diameter measured by image analysis method 21.2 nm, SiO ₂ concentration 40.7 mass%) to obtain an SiO ₂ concentration of 20 mass%. did.
[Example 6]
A tetraethoxylane solution in which 593.1 g of ethanol (laying water) was heated to 65 ° C. and mixed with 1188 g of tetraethoxysilane (ethyl silicate 28, SiO ₂ = 28.8 wt%) manufactured by Tama Chemical Co., Ltd. and 2255 g of ethanol, Further, 237.3 g of ultrapure water and an ammonia diluted solution obtained by mixing 40.5 g of 29.1% ammonia water were continuously added simultaneously over 6 hours. After completion of the addition, the mixture was further maintained at this temperature for 3 hours and aged. Thereafter, it was concentrated with an ultrafiltration membrane to a solid concentration of 15% by weight to remove unreacted tetraethoxysilane. Further, ethanol and ammonia were almost removed by a rotary evaporator to obtain a non-spherical silica sol having a solid content concentration of 12.6% by weight. The obtained non-spherical silica sol had the physical properties shown in Table 3.

For the obtained non-spherical silica sol, the amount of sodium contained in the non-spherical silica fine particles was measured according to the aforementioned “[11] Sodium quantification method” and found to be less than 1 ppm by mass.

Table 3 shows the results of evaluating the polishing characteristics of the obtained non-spherical silica sol by the above-mentioned [10] Evaluation method of polishing characteristics for thermal oxide film.
[Example 7]
A tetraethoxylane solution in which 593.1 g of ethanol (laying water) was heated to 75 ° C. and mixed with 1188 g of tetraethoxysilane (ethyl silicate 28, SiO ₂ = 28.8 wt%) manufactured by Tama Chemical and 2255 g of ethanol, In addition, 336.6 g of ultrapure water and an ammonia dilution mixed with 40.5 g of 29.1% ammonia water were continuously added simultaneously over 6 hours. After completion of the addition, the mixture was further maintained at this temperature for 3 hours and aged. Thereafter, it was concentrated with an ultrafiltration membrane to a solid concentration of 15% by weight to remove unreacted tetraethoxysilane. Further, ethanol and ammonia were almost removed by a rotary evaporator to obtain a non-spherical silica sol having a solid content concentration of 12.6% by weight. The obtained non-spherical silica sol had the physical properties shown in Table 3.

Table 3 shows the results of evaluating the polishing characteristics of the obtained non-spherical silica sol by the above-mentioned [10] Evaluation method of polishing characteristics for thermal oxide film.
[Example 8]
Ethanol 2372.4 g (bed water) was heated to 75 ° C., and tetraethoxysilane solution in which 1188 g of tetraethoxysilane (ethyl silicate 28, SiO ₂ = 28.8 wt%) manufactured by Tama Chemical Co., Ltd. and 2255 g of ethanol were mixed, In addition, 336.6 g of ultrapure water and an ammonia dilution mixed with 40.5 g of 29.1% ammonia water were continuously added simultaneously over 6 hours. After completion of the addition, the mixture was further maintained at this temperature for 3 hours and aged. Thereafter, it was concentrated with an ultrafiltration membrane to a solid concentration of 15% by weight to remove unreacted tetraethoxysilane. Further, ethanol and ammonia were almost removed by a rotary evaporator to obtain a non-spherical silica sol having a solid content concentration of 12.6% by weight. The obtained non-spherical silica sol had the physical properties shown in Table 3.

Table 3 shows the results of evaluating the polishing characteristics of the obtained non-spherical silica sol by the above-mentioned [10] Evaluation method of polishing characteristics for thermal oxide film.
[Comparative Example 3]
Tetraethoxysilane (manufactured by Tama Chemical Co., Ltd .: ethyl silicate 28, SiO ₂ = 28 mass%) 532.5 g is dissolved in 2450 g of a water-methanol mixed solvent [weight ratio of water to methanol = 2: 8]. 2982.5 g of ethoxysilane solution and 596.% by weight aqueous ammonia solution 596. 4 g was simultaneously added to a water-methanol mixed solvent maintained at 60 ° C. (consisting of 139.1 g of pure water and 169.9 g of methanol) over 20 hours. In addition, it was ammonia / tetraethoxysilane = 0.034 (molar ratio). After completion of the addition, the mixture was further aged at 65 ° C. for 3 hours.

Thereafter, unreacted tetraethoxysilane, methanol, and ammonia are removed almost completely with an ultrafiltration membrane, purified with both ion exchange resins, and then concentrated with an ultrafiltration membrane to obtain a silica sol having a solid concentration of 20% by mass. Obtained. The measurement results regarding this silica sol are shown in Table 1.

For the obtained spherical silica sol, the amount of sodium contained in the spherical silica fine particles was measured according to the above-mentioned “[11] Sodium quantification method” and found to be less than 1 ppm by mass.

The results of evaluating the polishing characteristics of the obtained silica sol by the above-mentioned [10] Evaluation method of polishing characteristics for thermal oxide film are shown in Table 3.

The non-spherical silica sol of the present invention has high utility as an abrasive. In addition, it has excellent physical properties such as filling properties, oil absorption properties, electrical properties, and optical properties, so it is expected to be applied to paint additives, resin additives, ink receiving layer components, cosmetic components, etc. .

Claims

The average particle size measured by the dynamic light scattering method is in the range of 3 to 200 nm, the minor axis / major axis ratio is in the range of 0.01 to 0.8, and the specific surface area is in the range of 10 to 800 m 2 / g. A non-spherical silica sol, wherein non-spherical silica fine particles having a plurality of hook-shaped protrusions are dispersed in a dispersion medium.
On a plane including the major axis of the non-spherical silica fine particles having the ridge-like projections, from any point on the outer edge of the non-spherical silica fine particles, a straight line passing through the point on the outer edge and orthogonal to the major axis and the length When an XY curve is drawn, where Y is the distance to the intersection B with the axis and X is the distance from one intersection A between the outer edge of the non-spherical silica fine particle and the major axis to the intersection B, The non-spherical silica sol according to claim 1, wherein the XY curve has a plurality of maximum values.
On a plane including the major axis of the non-spherical silica fine particles having the ridge-like projections, from any point on the outer edge of the non-spherical silica fine particles, a straight line passing through the point on the outer edge and orthogonal to the major axis and the length The non-spherical silica sol according to claim 1 or 2, wherein when the distance to the intersection B with the axis is Y, the coefficient of variation of the distance Y is in the range of 5 to 50%.
The non-spherical silica sol according to any one of claims 1 to 3, wherein the number of non-spherical silica fine particles having ridge-like projections is 50% or more of the total number of silica fine particles as a dispersoid. .
The non-spherical silica sol according to any one of claims 1 to 4, wherein the non-spherical silica fine particles having ridge-like protrusions are composed of [SiO 4/2 ] units.
5. The non-spherical silica fine particles having ridge-like protrusions are made of polysiloxane composed of [SiO 4/2 ] units obtained by hydrolysis of tetraethoxysilane. Non-spherical silica sol.
7. The non-spherical silica sol according to claim 5, wherein a ratio of sodium contained in the non-spherical silica fine particles having the hook-shaped protrusions is 100 ppm by mass or less.
An abrasive comprising the non-spherical silica sol according to any one of claims 1 to 7.
A polishing composition comprising the non-spherical silica sol according to any one of claims 1 to 7.
In the presence of an electrolyte composed of a salt of a strong acid (the number of equivalents of the electrolyte is represented by (EE)), 50 to 2500 parts by mass of B solution (silica conversion) is added to 100 parts by mass of A liquid (silica conversion) below. The liquid B is added so that the equivalent ratio of the alkali to the electrolyte (EA / EE) is in the range of 0.4 to 8 when growing the non-spherical seed silica fine particles. Item 6. A method for producing a non-spherical silica sol according to any one of Items 5 to 6.
Liquid A: Non-spherical seed silica fine particles having an average particle diameter measured by a dynamic light scattering method in the range of 3 to 200 nm and a minor axis / major axis ratio in the range of 0.01 to 0.8 are dispersed in the dispersion medium. Nonspherical seed silica sol B liquid: An aqueous alkali silicate solution (the number of equivalents of alkali contained in B liquid is represented by (EA))
11. The non-spherical silica sol according to claim 10, wherein the liquid B and the electrolyte are added to the liquid A over a period of 15 minutes to 10 hours in a temperature range of 40 to 150 ° C., and are aged. Method.
The temperature range of the mixed solvent containing a water-soluble organic solvent and water is maintained at 30 to 150 ° C., and 1) a water-soluble organic solvent solution of a tetrafunctional silane compound represented by the following general formula (1) And 2) Add the alkaline catalyst solution simultaneously or intermittently, and after completion of the addition, maintain this liquid in a temperature range of 30 to 150 ° C., thereby hydrolyzing and condensing the tetrafunctional silane compound. The method for producing a non-spherical silica sol according to claim 5 or 6, wherein the molar ratio of water to the tetrafunctional silane compound is in the range of 2 to 4 in producing the non-spherical silica sol. .

(In the formula (1), R is an alkyl group having 2 to 4 carbon atoms.)
The method for producing a non-spherical silica sol according to claim 12, wherein the tetrafunctional silane compound is tetraethoxysilane.