JP3160820B2 - Abrasive composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an abrasive composition.
More specifically, the present invention relates to a polishing composition which has a remarkably high polishing efficiency and can form an excellent polished surface.

[0002]

2. Description of the Related Art Conventionally, an abrasive composition comprising water and alumina has been known. However, the polishing rate is not sufficient. If the particle size of alumina is increased for the purpose of increasing the polishing rate, the polishing surface becomes rough. As a result, it could not be said that both the polishing rate and the surface state were satisfied.

Under such circumstances, it has been proposed to add various substances to a system of water and alumina in order to improve the polishing rate and the surface condition. For example, Japanese Patent Application Laid-Open No. 54-89389 discloses that aluminum nitrate is used as a polishing accelerator in water and alumina.
An abrasive for synthetic resins to which an aluminum salt such as aluminum sulfate or aluminum chloride is added has been proposed. On the other hand, in the past 10 years, the precision polishing of materials such as silicon and compound semiconductor substrates, various magnetic memory hard disks, and laser parts, for which the production on an industrial scale has increased dramatically, has been particularly demanded on the smoothness of the processed surface. , The level of defect-free (there is no defect such as scratches, orange peels, pits, protrusions, cracks, etc.) is much higher than the past polishing technology level, and on the other hand, production and inspection Since a large investment is required for equipment and the like, cost reduction by improving the production speed and reducing the loss of defective defects is also an important issue. Therefore, there is an extremely strong demand for polishing agents used in these fields to improve the surface condition and polishing rate.

With respect to such precision polishing, for example, Japanese Patent Application Laid-Open No. 25187/1987 discloses that aluminum nitrate also has a polishing promoting effect when polishing a memory hard disk. Further, salts of inorganic or organic acids such as nickel sulfate and aluminum oxalate, ammonium salts such as sulfuric acid, nitrites of metals, chelating compounds and the like are described as additives for improving the polishing rate and surface state. JP-A-3-277683 discloses an average primary particle diameter of 0.35 μm obtained by calcining alumina hydrate obtained by hydrolysis of organoaluminum as abrasive grains.
Hereinafter, it is described that when alumina having an α phase content of 95% or more and a square shape is used, the polishing rate and the surface state are improved.

[0005]

However, even with such known abrasives, the polishing rate and the surface condition are not always sufficient, and there is a demand for an abrasive with further improved performance. SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing composition which can improve the polishing rate and can obtain a polished product having an excellent surface condition.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to obtain a more excellent abrasive composition satisfying the above object, and as a result, when using alumina having specific physical properties as abrasive grains. The present inventors have found that a very excellent abrasive composition satisfying the above-mentioned object can be obtained, and arrived at the present invention. That is, the gist of the present invention is that the shape of the primary particles is angular and the average primary particle diameter is 2 μm or less, preferably 0.4 to
1 μm, the average secondary particle diameter is 10 μm or less, and the α phase content is 10 to 80%, preferably 20 to 60%.
% Of the alumina composition is present in an abrasive composition obtained by dispersing alumina in an aqueous medium .

Hereinafter, the present invention will be described in more detail. The abrasive composition of the present invention contains alumina as an abrasive component. The alumina has a primary particle shape of a square, an average primary particle size of 2 μm or less, and an average secondary particle size.
Is 10 μm or less, and the α phase content is 10 to 80%. Alumina is not particularly limited as long as it satisfies the above-mentioned rules. For example, alumina obtained by calcining alumina hydrate has a shape of primary particles depending on a raw material and its production conditions. Shape, needle shape, angular shape (shape of the edge portion of the particle is square), round shape (shape of the edge portion of the particle is rounded) and the like. Must be horny.

The average primary particle diameter of the alumina used in the present invention is 2 μm or less, preferably 0.4 to 1.0 μm.
m. If it is too small, the polishing rate will be low, and if it is too large, the polishing surface will be rough, such as scratches, which is not preferable. On the other hand, alumina hydrate undergoes a dehydration reaction when heated, passes through various intermediate phases such as γ, δ, and θ phases, and finally becomes an α phase, but the α phase content of alumina used in the present invention is 10%. Must be ~ 80%. If the α phase content is too small, the polishing rate will be low. Conversely, if it is too large, the polishing rate will be small. Preferred α
The phase content is between 20 and 60%.

The alumina of the present invention may be in the form of secondary particles in which some of these primary particles are bonded by sintering or the like as long as the average primary particle diameter is 2 μm or less. In this case, the average secondary particle diameter is usually 10 μm or less,
Preferably it is 0.4 to 2 μm. If it is too small, the polishing rate will be low, and if it is too large, the polishing surface will be rough, such as scratches.

[0010] The alumina used in the present invention is usually a hydrated alumina having primary particles of angular shape (eg, gibbsite, bayerite, nostrandite, boehmite) and intermediate alumina (γ-alumina, δ-alumina, θ-alumina). Alumina, etc.)
By calcining while maintaining that the shape of the primary particles is square and that the α phase content in alumina is 10 to 80%. Calcination is usually about 1050
It is preferred to work at a relatively low temperature of from about 1250C to about 1250C.
If the calcination temperature is too high, the primary particles are gradually rounded due to the progress of sintering, and the α phase content in alumina is 80%.
% Or more, in particular, the primary particles produced by hydrothermal treatment of gibbsite are angular boehmite,
Those calcined at a relatively low temperature of 1100 to 1200 ° C. under uniform temperature conditions are preferably used.

The abrasive composition of the present invention is an abrasive composition containing such alumina as an abrasive component. As a medium containing abrasive grains, water, mineral oil, fatty oil, fat,
Fats and oils, waxes, metal soaps, resins, alcohols and the like, but the abrasive composition of the present invention is particularly preferably an aqueous medium, and when an aqueous medium is used, a semiconductor substrate, a magnetic memory hard disk, a laser In precision polishing of a material such as a part, a favorable surface state is easily obtained, which is preferable. As the aqueous polishing medium, a medium mainly composed of water is usually used, but it is possible to include the below-mentioned additives as long as the polishing performance is not impaired.

The content of alumina in the abrasive composition is usually 1 to 30% by weight, preferably 2 to 15% by weight. If the amount is too small, the polishing rate will be low. On the other hand, if the amount is too large, uniform dispersion cannot be maintained. If the composition is in a liquid state, the viscosity of the slurry will be excessive and the handling will be difficult. Note that such a concentration range is a preferable concentration range at the time of actual polishing, and the polishing slurry composition of the present invention can be used by preparing a stock solution having a relatively high concentration and diluting it at the time of actual polishing. It is.

The polishing composition of the present invention may contain various known additives for the purpose of promoting polishing.
As additives, for example, salts of inorganic or organic acids such as aluminum sulfate, aluminum nitrate, nickel sulfate, aluminum oxalate, ethylenediaminetetraacetic acid,
Chelating compounds such as diethylenetriaminepentaacetic acid; acids or bases such as sulfuric acid, hydrochloric acid, nitric acid, acetic acid and sodium hydroxide; water-soluble alcohols such as ethanol, propanol and ethylene glycol; sodium alkyl benzene sulfonic acid; and naphthalene sulfonic acid. Examples include surfactants such as formalin condensates, organic polyanionic substances such as carboxymethyl cellulose salts and polyacrylates, celluloses such as cellulose and hydroxyethyl cellulose, and boehmite.

The inventors of the present invention have previously added a chelating compound to an abrasive composition containing alumina as an abrasive component,
Alternatively, it has been found that a high polishing rate and a good surface condition can be obtained by adding an aluminum salt or boehmite in addition to this (Japanese Patent Application No. 3-5).
No. 2750), and further excellent polishing performance can be exhibited by adding these additives to the abrasive composition of the present invention.

The polishing composition of the present invention comprises metal, glass,
Although used for polishing plastics and the like, it is particularly suitable for polishing memory hard disks and the like because a polished surface without defects can be obtained.

[0016]

In the abrasive composition of the present invention, the reason why the alumina exhibits the highest polishing rate when the alumina has a specific α-phase content is unknown, but if the α-phase content is too small, the polishing is carried out. The polishing rate is lowered because sufficient hardness and dispersibility cannot be obtained, and conversely, if it is too large, the edges of the primary particles which are square due to the progress of sintering are rounded, and the present invention It is considered that the shape, which is another characteristic, cannot be maintained in a square shape, and the polishing rate decreases. That is, it is considered that the α phase content of alumina gives the most suitable hardness, dispersibility, and shape for polishing.

[0017]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. The physical properties of the alumina used in the present invention were measured according to the methods described below.

Shape of primary particles: Observed by electron micrograph (magnification: 30,000). Average primary particle diameter: The individual primary particle diameters (average of the major axis and the minor axis) were read from an electron micrograph and averaged (n
= 10), and the average primary particle diameter. α-phase content: The integrated intensity of the (113) plane diffraction line is determined by X-ray diffraction measurement of the sample alumina, and a calibration curve obtained by performing the same measurement in advance using alumina having a known α-phase content is used. , Α phase content was calculated.

Examples 1 to 4 [Production of Alumina] Gibbsite was subjected to hydrothermal treatment at 200 ° C. for 4 hours in an autoclave, which was filtered and dried to obtain boehmite. This boehmite is calcined in an electric furnace at a uniform temperature in the range of 1100 ° C. to 1200 ° C. for 2 hours, and then pulverized and sized with a dry pulverizer to obtain an alumina having an average secondary particle diameter of 1 μm and a maximum particle diameter of 3 μm ( a),
(B), (c) and (d) were obtained. Table 1 shows the physical properties of this alumina. As a representative of Examples 1 to 4, Example 2
FIG. 1 shows an electron micrograph (magnification: 30,000) of the alumina (b). The aluminas (a), (c) and (d) of Examples 1, 3 and 4 had the same shape.

[Preparation of Abrasive Composition] The aluminas (a), (b), (c) and (d) obtained as described above are each dispersed in water using a high-speed mixer to form a slurry.
Furthermore, diethylenetriaminepentaacetic acid pentasodium salt, aluminum sulfate, and boehmite were added and mixed as polishing accelerators to prepare polishing compositions, respectively. On this occasion,
The proportions of the respective components are as follows: 5% by weight of alumina, 0.25% by weight of diethylenetriaminepentaacetic acid pentasodium salt, 1% by weight of aluminum sulfate, 0.25% by weight of boehmite, and 93.% of water in the abrasive composition. The content was adjusted to 5% by weight. As boehmite, Condea Ch
EMIE DISPERAL (registered trademark) was used.

[Polishing test] Electroless plating of nickel and phosphorus (nickel 90
3.5-inch memory hard disk (outer diameter about 95 mm)
Substrate was used. Polishing is performed using a double-side polishing machine (platen diameter φ64
0 mm).

A polishing pad of suede type (Domitex 25-3 manufactured by Daiichi Race Co., Ltd.) is provided on the upper and lower platens of the polishing machine.
Was attached, and five discs were loaded and polished for 3 minutes.
Polishing conditions were: processing pressure 125 g / cm ² , lower platen rotation speed 5
0 rpm and the abrasive supply amount was 150 cc / min. After polishing, the disk was washed and dried, and the polishing rate was determined from the weight loss. The surface condition of the polished disk was observed and evaluated. For surface observation, use a differential interference microscope.
Scratch, orange peel at 0x to 400x,
The presence or absence of pits, protrusions, etc. was observed. Table 1 shows the test results.

Comparative Example 1 An alumina having the physical properties shown in Table 1 was prepared in the same manner as in Example 1 except that the calcination conditions for boehmite were changed to 1080 ° C. for 2 hours. e) was prepared, an abrasive composition was prepared in the same manner as in Example 1, and a polishing test was performed. The results are shown in Table 1.

Comparative Example 2 The physical properties described in Table 1 were changed to alumina (f) in the same manner as in Example 1 except that the calcination conditions for boehmite were changed to 1220 ° C. for 2 hours. ) Was prepared, and an abrasive composition was prepared in the same manner as in Example 1.
A polishing test was performed. The results are shown in Table 1.

Comparative Example 3 An alumina having the physical properties shown in Table 1 was prepared in the same manner as in Example 1 except that the calcining conditions of the boehmite were changed to 1230 ° C. for 5 hours in the production of the alumina of Example 1. g) was prepared, a polishing composition was prepared in the same manner as in Example 1, and a polishing test was performed. The results are shown in Table 1.

Comparative Example 4 A hydrated alumina obtained by hydrolyzing an organoaluminum as in Example 1 was calcined at 1100 ° C. for 2 hours, pulverized by a dry pulverizer, and sized. A polishing composition was prepared and a polishing test was carried out in the same manner as in Example 1, except that alumina (h) having the physical properties shown in Table 1 was used. The results are shown in Table 1.

Comparative Example 5 In Comparative Example 4, the calcination condition of the hydrated alumina was 120
Table 2 was prepared in the same manner as in Comparative Example 4 except that the temperature was 0 ° C. and 2 hours.
Alumina (i) having the physical properties described in No. 1 was produced, a polishing composition was prepared in the same manner as in Comparative Example 4, and a polishing test was performed. The results are shown in Table 1. FIG. 2 shows an electron micrograph (× 30,000) of the alumina of Comparative Example 5.

[0028]

[Table 1]

[0029]

According to the abrasive composition of the present invention, an extremely high polishing rate and a good surface condition can be obtained, and the polishing efficiency can be remarkably increased. In particular, the abrasive composition of the present invention dispersed in an aqueous medium is extremely useful for precision polishing.

[Brief description of the drawings]

FIG. 1 is a drawing showing a particle structure of alumina (b) of Example 2 by an electron micrograph (× 30,000).

FIG. 2 is a drawing showing a particle structure of alumina (i) of Comparative Example 5 by an electron micrograph (× 30,000).

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Ito 1 Fukudacho, Joetsu City, Niigata Prefecture Inside the Naoetsu Plant of Mitsubishi Kasei Co., Ltd. (72) Inventor Sumio Kojima 1 Fukudacho, Joetsu City, Niigata Prefecture Mitsubishi Chemical Co., Ltd. Naoetsu Plant (56) References JP-A-3-277683 (JP, A) JP-A-3-234785 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09K 3/14 550 C01F 7/02

Claims (5)

(57) [Claims] 1. The shape of primary particles is square, the average primary particle size is 2 μm or less, and the α phase content is 10 to 80%.
Abrasive composition obtained by dispersing alumina as an aqueous medium in an aqueous medium . 2. The average primary particle diameter of alumina is 0.4 to 1
The abrasive composition according to claim 1, wherein the particle size is μm . 3. The average secondary particle diameter of alumina is 10 μm or less.
Claim 1 or 2 abrasive composition wherein it is below. 4. The method according to claim 1, wherein the content of alumina in the α phase is 20 to 60%.
Polishing compound according to any one of claims 1 to 3, characterized in that there. 5. The polishing composition according to claim 1, wherein the alumina is obtained by calcining boehmite produced by hydrothermal treatment of gibbsite.