JP4941501B2 - Polishing liquid for glass substrate, method for producing the same, polishing method for glass substrate using the polishing liquid, and glass substrate obtained by the polishing method - Google Patents

Description

  The present invention relates to a glass substrate polishing liquid and a method for producing the same. The present invention also relates to a glass substrate polishing method using the polishing liquid and a glass substrate obtained by the polishing method.

  In recent years, the demand for higher recording density for magnetic disks mounted on information processing equipment such as hard disk drives has been increasing. Under these circumstances, glass substrates have been widely used in place of conventional aluminum substrates. It is coming.

  In order to increase the recording capacity of the magnetic disk, the main surface of the glass substrate needs to be flatter, and high-precision polishing is required. For example, a glass substrate for a magnetic disk is obtained by cutting a donut-shaped circular glass plate (a circular glass plate having a circular hole in the center) from a glass plate, cutting the inner peripheral surface and the outer peripheral surface with a diamond grindstone, Surface lapping and end mirror polishing are sequentially performed, and polishing is performed with a polishing pad while applying a polishing liquid to the main surface of the circular glass plate. At this time, high precision polishing of the main surface of the glass substrate is possible to some extent by using extremely small abrasive particles of about 10 nm, but on the other hand, the polishing rate is slow and the productivity is significantly reduced.

Therefore, the polishing rate is also important. For example, Patent Document 1 discloses a polishing liquid containing a stable silica sol in which beaded colloidal silica particles in which spherical colloidal silica particles are connected only in one plane are dispersed in water. Is used for polishing aluminum disks, glass hard disks, quartz glass, quartz crystals, SiO ₂ oxide films of semiconductor devices, single silicon semiconductor wafers, and compound semiconductor wafers, it is disclosed that the polishing rate is improved.

  Patent Document 2 discloses that when a polishing liquid containing uneven colloidal silica particles having protrusions on the surface is used for polishing an InP wafer, the polishing rate is remarkably improved.

In addition, Patent Document 3 discloses a polishing material for quartz glass, soda lime glass, aluminosilicate glass, borosilicate glass, aluminoborosilicate glass, alkali-free glass, and crystallized glass. with Turkey Roidarushirika particles Yusuke 5-1 / 2 of the convex portion having a curvature radius average of two or more, both the smoothness of the polishing rate of the surface roughness that is satisfactory disclose.

JP 2001-11433 A Japanese Patent Laid-Open No. 2004-207417 JP 2008-13655 A

  However, the conventional polishing liquid is not at a level that satisfies both the polishing rate and the surface flatness. Further, the synthesis of the beaded colloidal silica particles described in Patent Document 1 requires an enormous amount of time of 30 to 3000 minutes, takes time for production, and increases the cost.

  Accordingly, an object of the present invention is to achieve both high-speed polishing and high flatness of the substrate surface in polishing a glass substrate such as a magnetic disk.

In order to achieve the above object, the present invention provides the following.
(1) Average particle diameter becomes linked uneven colloidal silica particles having a projection on the front surface with 10 to 50 nm, and a median diameter (D1) is in 30~150nm by a dynamic light scattering method, transmission electron Colloidal silica particle aggregates having a ratio (D1 / D2) to the average particle diameter (D2) measured by a microscope of 2 to 5 are dispersed in water , and the polishing rate / surface roughness (Ra) is 1. A polishing liquid for glass substrate, wherein the polishing liquid is 8 μm / (min · nm) or more .
(2) The glass substrate polishing liquid according to (1) above, wherein the concentration of the colloidal silica particle aggregate is 0.5 to 30% by mass in terms of SiO ₂ .
(3) A method for producing a polishing liquid for a glass substrate as described in (1) above, wherein a flocculant and irregular colloidal silica particles having an average particle diameter of 10 to 50 nm and having protrusions on the surface are added to a silicic acid-containing aqueous solution. A method for producing a polishing liquid for a glass substrate, comprising adjusting the pH of the liquid to 8 to 10 and then heating using a microwave.
(4) The method for producing a polishing liquid for a glass substrate according to the above (1), wherein the siliceous acid-containing aqueous solution is ion-exchanged so as to have a pH of 4 or less, and consists of lithium hydroxide, potassium hydroxide and sodium hydroxide. A method for producing a polishing liquid for a glass substrate, wherein the pH is adjusted to 9 to 14 using one or more selected from the following, followed by heating using microwaves.
(5) A method for polishing a glass substrate, comprising polishing the glass substrate using the glass substrate polishing liquid according to (1) or (2) above.
(6) A method for producing a glass substrate, comprising polishing the glass substrate using the glass substrate polishing liquid according to (1) or (2) above.
(7) The method for producing a glass substrate according to (6), wherein the glass substrate is a glass substrate for a magnetic disk.

  By using the glass substrate polishing liquid of the present invention, it is possible to realize a higher polishing rate and higher surface flatness than before, and the resulting glass substrate also has excellent surface flatness. Moreover, this glass substrate polishing liquid can be produced in a short time.

It is a figure which shows the continuous microwave heating apparatus used by this invention, (1-1) is sectional drawing of a longitudinal direction, (1-2) shows sectional drawing of the direction orthogonal to a longitudinal direction. It is the photograph which image | photographed the abrasive | polishing material obtained by the comparative example 4 with the transmission electron microscope. It is the photograph which image | photographed the abrasive | polishing material obtained in Example 4 with the transmission electron microscope.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  In the present invention, a colloidal silica particle aggregate (see FIG. 2B) in which concavo-convex colloidal silica particles having protrusions on the surface are connected is used as an abrasive for the glass substrate polishing liquid. In the present invention, the state in which the particles are cross-linked with silicic acid or the like is referred to as connection. The uneven colloidal silica particles are colloidal silica particles having protrusions of 1 nm or more on the surface, and the average particle diameter is 10 to 50 nm, preferably 15 to 40 nm. The concavo-convex colloidal silica particles are connected one-dimensionally, two-dimensionally or three-dimensionally to form a colloidal silica particle aggregate, and the size thereof is determined by the median diameter (D1 ) In the range of 30 to 150 nm, preferably (50 to 130) nm, and a ratio (D1 / D2; association ratio) to the average particle diameter (D2) measured by a transmission electron microscope of 2 to 5, preferably It is 3-5, More preferably, it is 3-4.5. When both the concave and convex colloidal silica particles and the colloidal silica particle aggregate are smaller than the above dimensions, the polishing rate is slow, and when it is large, flatness cannot be obtained. The association ratio is also the same. When it is smaller than 2, the polishing rate is slow, and when it is larger than 5, flatness cannot be obtained.

  Concave and convex colloidal silica particles are silica doll 30, silica doll 30B, silica doll 40, silica doll 30LL, silica doll 40KL (manufactured by Nippon Chemical Industry Co., Ltd.), PL2L, PL2 (manufactured by Fuso Chemical Industry Co., Ltd.), cataloid. Commercial products such as PPS-45PKH, Cataloid PPS-50 (JGC Catalysts & Chemicals Co., Ltd.), Ludox AS40, Ludox HS40, Ludox TM50 (produced by Grace Japan Co., Ltd.) can be used. It can also be produced according to a) to (d).

Step (a):
First, colloidal silica particles having no protrusions on the surface are dispersed in water, and the dispersion is adjusted to pH 10 or higher. Examples of the alkali used for pH adjustment include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, ammonia, sodium hydrogen carbonate and the like. In addition, an anion exchange resin may be used. If the pH of the liquid is less than 10, the amount of silicic acid dissolved in the colloidal silica particles is insufficient, and thus it becomes difficult to produce uneven colloidal silica particles.

Step (b):
Silicic acid is added to the dispersion in the step (a). As the silicic acid source, water glass is suitable, and examples thereof include sodium silicate (xNa ₂ O · ySiO ₂ ) equivalent to JIS K1408, that is, JIS No. 1, No. 2, No. 3 water glass. The concentration of silicic acid is 0.015 to 0.09 parts by mass, preferably (0.02 to 0.07) parts by mass with respect to 100 parts by mass of water as SiO ₂ . When the concentration of silicic acid is less than 0.015 parts by mass with respect to 100 parts by mass of water, projections may not be formed on the surface, and the concentration of silicic acid is more than 0.09 parts by mass with respect to 100 parts by mass of water. Then, gel-like silica is produced together with the uneven colloidal silica particles.

Step (c):
The dispersion liquid in the step (b) is adjusted to pH 9 or less and held for a predetermined time. Examples of the acid used for pH adjustment include hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, acetic acid, and citric acid. In addition, a cation exchange resin may be used. If the pH of the liquid is more than 9, the amount of silicic acid dissolved is large and silicic acid does not precipitate, making it difficult to produce uneven colloidal silica particles. In view of the stability of the formed uneven colloidal silica particles, pH 8 to 9, or pH 1.5 to 2.5 is preferable. Outside this pH range, the stability is poor, and the gelation is likely to proceed if stored for a long time. The holding time is set according to the size of the projections of the concavo-convex colloidal silica particles.

Step (d):
The produced concavo-convex colloidal silica particles are recovered from the dispersion liquid in the step (c). In addition, confirmation of protrusion formation can be confirmed with a transmission electron microscope.

  In order to connect the uneven colloidal silica particles to form an aggregate, for example, the following steps (A) to (E) are performed.

Step (A):
A silicic acid-containing aqueous solution is prepared, and the pH of the solution is adjusted to 4 or less. The water glass used above is suitable as the silicic acid source, and the concentration of the water glass in the aqueous solution is preferably 0.5 to 15% by mass as SiO ₂ . If the concentration of the water glass is 0.5% by mass or more, the amount of water is suppressed and the production efficiency of silicic acid from the water glass is improved, but if it exceeds 15% by mass, gelation occurs during the synthesis of silicic acid. Become. For pH adjustment of the liquid, it is preferable to add a cation exchange resin. Examples of the cation exchange resin include Diaion SK104, SK1B, SK1BH, SK110, SK112, PK212, PK216, and PK228 (manufactured by Mitsubishi Chemical Corporation). When the pH of the liquid exceeds 4, gelation of silicic acid proceeds.

Step (B):
A metal salt is added to the silicic acid-containing aqueous solution in the above step (A) as an aggregating agent for uneven colloidal silica particles. Examples of the metal salt include magnesium, calcium, barium, titanium, manganese, iron, cobalt, nickel, and aluminum salts. The amount of the metal salt is converted into an oxide and is 1 to 10 parts by mass with respect to 100 parts by mass of silicic acid (referred to as SiO ₂ ). If the amount of the metal salt is 1 part by mass or more, an aggregating effect can be exhibited, but if it exceeds 10 parts by mass, gelation occurs.

Step (C):
The uneven colloidal silica particles are dispersed in water, and the pH of the liquid is adjusted to 2-4. The concentration of the uneven colloidal silica particles is preferably 20 to 50% by mass in terms of SiO ₂ . If the uneven colloidal silica particle concentration is 20% by mass or more, a colloidal silica particle aggregate can be efficiently prepared, but if it exceeds 50% by mass, gelation occurs. For pH adjustment, when the liquid is acidic, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous calcium hydroxide solution, an aqueous sodium carbonate solution, aqueous ammonia, an aqueous sodium hydrogen carbonate solution, or the like is used. An anion exchange resin may also be used. On the other hand, when the liquid is alkaline, hydrochloric acid, sulfuric acid, nitric acid, carbonic acid, acetic acid, citric acid and the like are used. Moreover, you may use a cation exchange resin.

Step (D):
The concavo-convex colloidal silica particle dispersion liquid in the step (C) and the silicic acid-containing aqueous solution to which the flocculant in the step (B) is added are sufficiently mixed, and the pH of the liquid is adjusted to 8-10. To adjust the pH of the solution, an alkaline aqueous solution such as an aqueous solution of sodium hydroxide, aqueous solution of potassium hydroxide, aqueous solution of calcium hydroxide, aqueous solution of sodium carbonate, aqueous ammonia or aqueous solution of sodium hydrogen carbonate is added dropwise. It is desirable to set it as 5-20 g / min in conversion of 1 mass% sodium hydroxide aqueous solution with respect to liter. If the dropping speed is less than 5 g / min, it takes time for aggregation and the efficiency is poor, and if it exceeds 20 g / min, gelation may occur at the time of addition. In addition, an anion exchange resin may be used.

Step (E):
The liquid of the said process (D) is heated, and uneven | corrugated colloidal silica particles are connected through a silicic acid, and it is set as an aggregate. The heating temperature is preferably 150 ° C to 250 ° C, particularly preferably 180 ° C to 230 ° C. If the heating temperature is less than 150 ° C., the uneven colloidal silica particles may not be connected to each other, and if the heating temperature exceeds 250 ° C., gelation may occur when the temperature is raised. A microwave heating device or an autoclave device can be used for heating, but it is preferable to use a microwave heating device in order to shorten the heating time. By using the microwave heating device, it is possible to sufficiently connect even with a heating time of about 0.5 to 5 minutes. In addition, as a microwave heating apparatus, the continuous microwave heating apparatus of the following structure is preferable.

  FIG. 1 (1-1) is a cross-sectional view in the longitudinal direction of the continuous microwave heating apparatus 1, and FIG. 1 (1-2) is a cross-sectional view in the direction orthogonal to the longitudinal direction of the continuous microwave heating apparatus 1. It is. As shown in the drawing, a metal container 5 having a window 4 (opening) through which microwaves are transmitted, a microwave oscillator 2 that radiates microwaves to the window 4 of the container 5, and a through-hole disposed in the container 5. The reaction liquid flow path 6 and the filled layer 7 made of a microwave permeable solid substance filled between the container 5 and the reaction liquid flow path 6 are transmitted through the window 4 of the container 5. The liquid 8 of the said process (D) which the wave 3 flows through the inside of the reaction liquid flow path 6 is heated, and the uneven | corrugated colloidal silica particles in a liquid are connected with silicic acid.

  Here, the microwave refers to an electromagnetic wave having a wavelength of 0.1 to 1000 mm and a frequency of 300 MHz to 3 THz. Note that electromagnetic waves having a frequency of 915 MHz, 2.45 GHz, and 5.8 GHz are widely used.

  As the microwave oscillator 2, a klystron, a gyrotron, or the like can be used, and the microwave output depends on the type of the liquid 8 flowing through the reaction liquid flow path 6, the reaction pressure, the reaction set temperature, the flow rate, the speed, and the like. However, it is about 100-5000W.

  The microwave oscillator 2 may be configured to be directly attached to the window 4 of the metal container 5 so that the microwave 3 oscillated from the microwave oscillator 2 is directly irradiated, but as illustrated, It is configured to be connected to the window 4 of the metal container 5 through a waveguide 9 such as a metal rectangular waveguide or a circular waveguide for microwave propagation.

  The microwave 3 oscillated from the microwave oscillator 2 propagates through the waveguide 9, is irradiated onto the window 4, propagates through the metal container 5 through the window 4, and further passes through the filling layer 7 to react. The liquid 8 in the liquid flow path 6 is irradiated. While the traveling direction of the microwave 3 is controlled while propagating through the waveguide 9, the microwave 3 diffuses when propagating through the window 4. The microwave 3 which has not reached the reaction liquid flow path 6 and has not been absorbed by the liquid 8 due to progressing by diffusion passes through the packed bed 7 and is reflected by the inner wall surface of the metal container 5. And is absorbed by the liquid 8. By repeating this, the connection between the uneven colloidal silica particles in the liquid 8 is promoted.

  The number of windows 4 provided in the metal container 5 is not limited to one, and a plurality of windows can be provided. However, the number of windows is preferably 1 to 5 from the viewpoint of safety. When a plurality of windows 5 are provided, the periphery of the reaction liquid flow path 6 is surrounded along the flow of the liquid 8 flowing through the reaction liquid flow path 6 or with respect to the flow direction of the liquid 8 flowing through the reaction liquid flow path 6. Deploy. And the waveguide 9 and the microwave oscillator 2 are arrange | positioned in each window 4, and the liquid 8 which distribute | circulates the reaction liquid flow path 6 can be heated continuously.

  Further, in order to increase the efficiency of microwave irradiation, the ratio (Sa) / (Sb) between the cross-sectional area (Sa) of the metal container 5 and the cross-sectional area (Sb) of the reaction liquid channel 6 is 4 or more. Is preferably 60 or more, particularly preferably 80 or more and 100 or less. Each cross-sectional shape of the metal container 5 and the reaction liquid channel 6 may be a circle, a square, or the like, and may be of the same type or a different shape. 5 and the reaction liquid channel 6 are preferably circular in cross section, and it is particularly preferable that they are arranged concentrically. Further, the circular cross-sectional diameter (a) of the metal container 5 having such a configuration is preferably 4 mm or more from the viewpoint of propagating the microwave into the metal container, and the circular cross-sectional diameter of the reaction liquid channel 6 The ratio (a) / (b) to (b) is more preferably 2 or more. In addition, the upper limit of the circular cross-sectional diameter (a) of the metal container 5 is about 1000 mm, and the upper limit of the circular cross-sectional diameter (b) of the reaction liquid channel 6 is about 500 mm.

  Further, it is also preferable that the cross section of the metal container 5 is square, the cross section of the reaction liquid channel 6 is circular, and the reaction liquid channel 6 is coaxially disposed in the metal container 5. In this case, it is preferable that the length (c) of the short side constituting the square is 4 mm or more. This is because the microwave can be propagated well into the metal container 5. Further, the ratio (c) / (b) between the short side length (c) and the circular cross-sectional diameter (b) of the reaction liquid channel 6 is preferably 2 or more. This is because the liquid 8 can be more uniformly irradiated with the microwave. When the container cross section is a square, each side may be defined as the short side. Moreover, if the length of the short side in the case of a rectangle is the said preferable range, it will not restrict | limit in particular about the length (d) of a long side.

  Furthermore, the liquid pressure of the liquid 8 flowing through the reaction liquid flow path 6 is 0.001 to 10 MPa, more preferably 0.001 to 3 MPa.

  The concavo-convex colloidal silica particle aggregates thus obtained are those in which the concavo-convex colloidal silica particles are firmly connected by silicic acid, and are dispersed in the polishing liquid while maintaining the state of the aggregates. And when it uses for grinding | polishing of a glass substrate, the surface of a glass substrate is horizontally moved, maintaining the state of an aggregate substantially, without isolate | separating into each uneven | corrugated colloidal silica particle. Therefore, polishing with a high polishing rate and excellent flatness can be performed.

  Moreover, the polishing liquid containing the aggregate of uneven colloidal silica particles can also be prepared as in the following steps (F) to (H).

Step (F):
First, in the same manner as in the above step (A), a silicic acid-containing aqueous solution is prepared, and the pH is adjusted to 4 or less.

Process (G):
The pH of the liquid in the step (F) is adjusted to 9 to 14, preferably 9 to 12. Lithium hydroxide, potassium hydroxide, and sodium hydroxide are used for pH adjustment, but a plurality of these hydroxides may be used in combination.

Step (H):
The liquid of the said process (G) is heated using said microwave heating apparatus.

  There is no restriction | limiting as long as the polishing liquid contains the aggregate of uneven colloidal silica particles, and it can be set as the aqueous slurry which further contains surfactant, an inorganic acid, or an organic acid.

  The present invention also relates to a method for polishing a glass substrate using the above polishing liquid. Examples of the glass substrate to be polished include quartz glass, soda lime glass, aluminosilicate glass, borosilicate glass, aluminoborosilicate glass, alkali-free glass, crystallized glass, and tempered glass. Below, the grinding | polishing method of the glass substrate for magnetic discs is illustrated.

  First, for example, a circular hole is formed in the center of a circular glass plate cut out from a silicate glass formed by a float process, and then chamfering, main surface lapping, and end mirror polishing are sequentially performed. Further, the main surface lapping step may be divided into a rough lapping step and a fine lapping step, and a shape processing step (drilling at the center of the circular glass plate, chamfering, end polishing) may be provided between them. A chemical strengthening step may be provided after the main surface polishing step.

  Next, the main surface is polished. In the present invention, a polishing liquid using the above-mentioned aggregate of uneven colloidal silica particles as an abrasive is used. The main surface may be polished in the same manner as in the past, for example, by sandwiching a circular glass plate between two polishing pads and rotating the polishing pad while supplying polishing liquid to the interface between the polishing pad and the circular glass plate. Do.

As a polishing pad, a urethane foam resin having a Shore D hardness of 45 to 75, a compression ratio of 0.1 to 10% and a density of 0.5 to 1.5 g / cm ³ , a Shore A hardness of 30 to 99, and a compression A foamed urethane resin having a rate of 0.5 to 10% and a density of 0.2 to 0.9 g / cm ³ , or a Shore A hardness of 5 to 65, a compressibility of 0.1 to 60%, and a density of 0 What consists of foaming urethane resin which is 0.05-0.4 g / cm < ³ > is typical. The Shore A hardness of the polishing pad is preferably 20 or more. If it is less than 20, the polishing rate may decrease.

  The polishing pressure is preferably 4 kPa or more. If it is less than 4 kPa, the stability of the glass substrate at the time of polishing is lowered and fluttering tends to occur, and as a result, the waviness of the main surface may increase.

  The polishing amount of the main surface is suitably from 0.3 to 1.5 μm, and the supply amount and polishing time of the polishing liquid, the silica concentration in the polishing liquid, the polishing pressure, the rotational speed, etc. are adjusted.

  The main surface may be preliminarily polished before the main surface polishing. This preliminary main surface polishing can be performed, for example, by sandwiching a circular glass plate with a polishing pad and rotating the polishing pad while supplying a cerium oxide abrasive slurry.

  After the main surface polishing, the glass substrate for magnetic disk is obtained by washing and drying. Cleaning and drying are performed by a known method. For example, immersion in an acidic detergent solution, immersion in an alkaline detergent solution, scrub washing with veggulin and an alkaline detergent, immersion in an alkaline detergent solution, scrub washing with bergulin and an alkaline detergent After performing ultrasonic cleaning in an alkaline detergent solution, ultrasonic cleaning in pure water, ultrasonic cleaning in pure water, spin drying or isopropyl alcohol vapor drying, etc. Dry by the method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. The median diameter (D1), average particle diameter (D2), association ratio (D1 / D2), polishing test method, polishing rate, and surface roughness of the abrasive are as follows.

(Average particle diameter (D2))
The particle diameter of 100 particles randomly selected from a TEM image obtained with a transmission electron microscope (TEM) (manufactured by JEOL Ltd., JEM-1230) was measured and calculated by averaging. . An electron micrograph of Comparative Example 4 is shown in FIG. 2A and an electron micrograph of Example 4 is shown in FIG. 2B.

(Median diameter (D1) and association ratio (D1 / D2))
The median diameter (D1) was measured by a dynamic light scattering method using Microtrac UPA (manufactured by Nikkiso Co., Ltd.), and the ratio with the average particle diameter (D2) was determined.

(Polishing test method)
The silicate glass disk was polished under the following conditions.
・ Polishing tester: FAM-12B, manufactured by Speed Fam Co., Ltd. ・ Polishing pad: KZBR-3N-101U, manufactured by Fujibo Atago Co., Ltd.
・ Polishing liquid supply speed: 20cc / min
・ Polishing time: 10 min
・ Polishing load: 12 kPa
・ Abrasive concentration: 15% by mass (SiO ₂ equivalent)
・ Polishing solution pH: 2 (adjusted with 1M nitric acid)

(Polishing speed)
The polishing amount was determined from the difference in mass before and after polishing.

(Surface roughness)
The surface roughness of the polished surface after polishing was measured using an AFM manufactured by Veeco.

Example 1
In a glass container, put 14.3 g of water glass No. 3 (Nippon Chemical Industry Co., Ltd., 29% by mass) and 100 g of water, stir for 15 minutes, and then add a cation exchange resin (SK1BH manufactured by Mitsubishi Chemical Corporation). Added and stirred for 15 minutes. This aqueous solution was filtered to obtain 114.3 g of a 3.6% by mass silicic acid aqueous solution. The pH was 3.3.

  To this silicic acid aqueous solution, 7.6 g of a 10% by mass calcium nitrate aqueous solution was added while stirring, and stirred for 15 minutes to obtain an aqueous solution 1. The pH was 4.1.

  A cation exchange resin (SK1BH manufactured by Mitsubishi Chemical Corporation) was added to 255 g of silica dol 40 (Nippon Chemical Industry Co., Ltd., pH 9.1) to obtain a pH of 3.1 to obtain an aqueous solution 2.

  The aqueous solution 2 was added to the aqueous solution 1 being stirred and stirred for 15 minutes to obtain an aqueous solution 3. The pH was 4.1.

  While stirring, 40 g of a 2 mass% aqueous sodium hydroxide solution was added to the aqueous solution 3 at a dropping rate of 2 g / min, and the mixture was stirred for 30 minutes to obtain an aqueous solution 4. The pH was 9.1.

  The aqueous solution 4 was put in a microwave heating apparatus and held at 210 ° C. for 3 minutes to obtain a dispersion liquid in which uneven colloidal silica particle aggregates were dispersed. When observed by TEM, the colloidal silica particles are connected, and this connection is considered to be made by crosslinking with silicic acid. The average particle diameter (D2) was 31 nm, the median diameter (D1) was 78.5 nm, and the association ratio (D1 / D2) was 2.5.

  Moreover, the polishing liquid containing 15 mass% of obtained uneven | corrugated colloidal silica particle aggregates was prepared, and the grinding | polishing test was done. Table 1 shows the results of the polishing rate and the polishing surface roughness.

(Example 2)
A concavo-convex colloidal silica particle aggregate dispersion was obtained in the same manner as in Example 1 except that it was held at 210 ° C. for 5 minutes with a microwave heating apparatus. When observed by TEM, the colloidal silica particles are connected, and this connection is considered to be made by crosslinking with silicic acid. The average particle diameter (D2) was 31 nm, the median diameter (D1) was 120 nm, and the association ratio (D1 / D2) was 4. Moreover, the polishing liquid containing 15 mass% of obtained uneven | corrugated colloidal silica particle aggregates was prepared, and the grinding | polishing test was done. Table 1 shows the results of the polishing rate and the polishing surface roughness.

(Example 3)
The same procedure as in Example 2 was performed except that silica doll 30 (manufactured by Nippon Chemical Industry Co., Ltd., pH 9.2) was used instead of silica doll 40 (manufactured by Nippon Chemical Industry Co., Ltd., pH 9.2), and the addition amount was changed to 340 g. A dispersion of concavo-convex colloidal silica particle aggregates was obtained. When observed by TEM, the colloidal silica particles are connected, and this connection is considered to be made by crosslinking with silicic acid. The average particle diameter (D2) was 13 nm, the median diameter (D1) was 51 nm, and the association ratio (D1 / D2) was 4.2. Moreover, the polishing liquid containing 15 mass% of obtained uneven | corrugated colloidal silica particle aggregates was prepared, and the grinding | polishing test was done. Table 1 shows the results of the polishing rate and the polishing surface roughness.

Example 4
In a glass container, 28.4 g of water glass No. 4 (manufactured by Nippon Chemical Industry Co., Ltd., 24% by mass) and 108.1 g of water are stirred for 15 minutes, and then a cation exchange resin (SK1BH manufactured by Mitsubishi Chemical Corporation). ) Was added and stirred for 15 minutes. This aqueous solution was filtered to obtain 136.5 g of a 5 mass% silicic acid aqueous solution. The pH was 3.0.

  To this silicic acid aqueous solution, 23.4 g of a 2 mass% sodium hydroxide aqueous solution was added at a dropping rate of 2 g / min while stirring, and stirred for 30 minutes to obtain an aqueous solution. The pH was 10.3.

  This aqueous solution was put into a microwave heating apparatus and held at 180 ° C. for 15 minutes to obtain an aqueous solution containing chain colloidal silica particles connected with uneven colloidal silica particles (see FIG. 2B). This connection is considered to be made by cross-linking with silicic acid. The average particle diameter (D2) was 10 nm, the median diameter (D1) was 41 nm, and the association ratio (D1 / D2) was 4.1. Moreover, the polishing liquid containing 15 mass% of obtained uneven | corrugated colloidal silica particle aggregates was prepared, and the grinding | polishing test was done. Table 1 shows the results of the polishing rate and the polishing surface roughness.

(Comparative Example 1)
A polishing liquid containing 15% by mass of silica doll 40 (manufactured by Nippon Chemical Industry Co., Ltd., pH 9.1) as an abrasive was prepared and subjected to a polishing test. Table 1 shows the results of the polishing rate and the polishing surface roughness. The average particle diameter (D2) was 31 nm, the median diameter (D1) was 40 nm, and the association ratio (D1 / D2) was 1.2.

(Comparative Example 2)
A polishing liquid containing 15% by mass of Snowtex XL (manufactured by Nissan Chemical Industries, Ltd., pH 9.2) as an abrasive was prepared and subjected to a polishing test. Table 1 shows the results of the polishing rate and the polishing surface roughness. The average particle diameter (D2) was 68 nm, the median diameter (D1) was 84 nm, and the association ratio (D1 / D2) was 1.2.

(Comparative Example 3)
A polishing liquid containing 15% by mass of Snowtex PS-MO (manufactured by Nissan Chemical Industries, Ltd., pH 3.0) as an abrasive was prepared and subjected to a polishing test. Table 1 shows the results of the polishing rate and the polishing surface roughness. The average particle diameter (D2) was 31 nm, the median diameter (D1) was 62 nm, and the association ratio (D1 / D2) was 2.1.

(Comparative Example 4)
A polishing liquid containing 15% by mass of Compol 20 (Fujimi Corp., pH 3.0) as an abrasive was prepared, and a polishing test was performed. Table 1 shows the results of the polishing rate and the polishing surface roughness. The average particle diameter (D2) was 21 nm, the median diameter (D1) was 22 nm, and the association ratio (D1 / D2) was 1.0.

  As shown in Table 1, it is possible to achieve both high-speed polishing and high flatness by using a polishing liquid having an uneven colloidal silica particle aggregate according to the present invention as an abrasive.

DESCRIPTION OF SYMBOLS 1 Continuous microwave reactor 2 Microwave oscillator 3 Microwave 4 Window 5 Metal container 6 Reaction liquid flow path 7 Packing layer 8 Liquid 9 Waveguide

Claims (7)

Be linked uneven colloidal silica particles having an average particle diameter with a protrusion on the front surface at 10~50nm is, and the median diameter (D1) is in 30~150nm by dynamic light scattering method, measured by transmission electron microscopy Colloidal silica particle aggregates having a ratio (D1 / D2) to the average particle diameter (D2) of 2 to 5 are dispersed in water , and the polishing rate / surface roughness (Ra) is 1.8 μm / (Min · nm) or more, A polishing liquid for glass substrate, The polishing liquid for glass substrates according to claim 1, wherein the concentration of the colloidal silica particle aggregate is 0.5 to 30% by mass in terms of SiO ₂ .   It is a manufacturing method of the polishing liquid for glass substrates of Claim 1, Comprising: A flocculant and the uneven | corrugated colloidal silica particle which has a processus | protrusion on the surface with an average particle diameter of 10-50 nm are added to silicic acid containing aqueous solution, and pH of a liquid After adjusting to 8-10, it heats using a microwave, The manufacturing method of the polishing liquid for glass substrates characterized by the above-mentioned.   The method for producing a polishing liquid for a glass substrate according to claim 1, wherein the pH is adjusted to 4 or less by ion exchange of the silicic acid-containing aqueous solution and selected from the group consisting of lithium hydroxide, potassium hydroxide and sodium hydroxide. The manufacturing method of the polishing liquid for glass substrates characterized by heating after using pH above to 9-14 using a microwave.   A glass substrate polishing method comprising polishing the glass substrate using the glass substrate polishing liquid according to claim 1.   A method for producing a glass substrate, comprising polishing a glass substrate using the glass substrate polishing liquid according to claim 1.   The method for producing a glass substrate according to claim 6, wherein the glass substrate is a glass substrate for a magnetic disk.