JPH05271647A - Abrasive composition - Google Patents

Abstract

PURPOSE:To obtain an abrasive composition improved in abrading rate and surface finish by using a specified alumina as the abrasive grain component. CONSTITUTION:Boehmite produced by the hydrothermal treatment of gibbsite and being hornlike in the form of a primary particle is calcined at 1100-1200 deg.C to obtain an alumina which is hornlike in the form of a primary particle and has a mean primary particle diameter of 2mu or below and an alpha phase content of 10-80%. An abrasive grain component comprising 1-30wt.% this alumina and a salt of an inorganic or organic acid, a chelate compound, an acid or a base, a water-soluble alcohol a surfactant a cellulose boebmite, etc., are dispersed in an aqueous medium.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an abrasive composition.
More specifically, it relates to an abrasive composition having extremely high polishing efficiency and capable of forming an excellent polishing surface.

[0002]

2. Description of the Related Art Conventionally, an abrasive composition composed of water and alumina has been known, but the polishing rate is not sufficient, and when the particle size of alumina is increased to increase the polishing rate, the polishing surface becomes rough. Therefore, it cannot be said that both the polishing rate and the surface condition are satisfied.

Under such circumstances, it has been proposed to add various substances to the system of water and alumina in order to improve the polishing rate and the surface condition. For example, in JP-A-54-89389, water and alumina are added to aluminum nitrate as a polishing accelerator,
There has been proposed a polishing agent for synthetic resins to which an aluminum salt such as aluminum sulfate or aluminum chloride is added. On the other hand, in the precision polishing of materials such as silicon and compound semiconductor substrates, various magnetic memory hard disks, laser parts, etc., for which industrial scale production has increased dramatically over the past 10 years, the smoothness of the machined surface is particularly high. In addition, the required level for defect-freeness (no defects such as scratches, orange peels, pits, protrusions, and cracks) is much higher than the past polishing technology level, while production and inspection Since a large amount of investment is required in equipment, cost reduction by improving production speed and reducing defective defects is also an important issue. Therefore, even for the abrasives used in these fields, there is an extremely strong demand for improving the surface condition and the polishing rate.

Regarding such precision polishing, for example, Japanese Patent Laid-Open No. 62-25187 discloses that aluminum nitrate has a polishing promoting effect even when polishing a memory hard disk. Furthermore, salts of inorganic or organic acids such as nickel sulfate and aluminum oxalate, ammonium salts such as sulfuric acid, metal nitrites, chelating compounds, etc. are described as additives for improving the polishing rate and surface condition. Further, in JP-A-3-277683, an average primary particle diameter of 0.35 μm obtained by calcining alumina hydrate obtained by hydrolysis of organic aluminum as abrasive grains
It is described below that the use of alumina having an α-phase content of 95% or more and a square shape improves the polishing rate and the surface condition.

[0005]

However, even among such known polishing agents, the polishing rate and the surface condition are not always sufficient, and further polishing agents having improved performance are desired. An object of the present invention is to provide an abrasive composition capable of improving the polishing rate and obtaining a polished product having an excellent surface condition.

[0006]

Means for Solving the Problems As a result of intensive investigations by the present inventors to obtain a more excellent polishing composition satisfying the above-mentioned object, when alumina having specific physical properties was used as abrasive grains, It was found that an extremely excellent abrasive composition satisfying the above-mentioned object can be obtained, and the present invention has been accomplished. That is, the gist of the present invention is that the shape of the primary particles is angular, the average primary particle diameter is 2 μm or less, and the α phase content is 10 to 80%, and the alumina is contained as an abrasive grain component. Which is present in the polishing composition.

The present invention will be described in more detail below. The abrasive composition of the present invention contains alumina as an abrasive grain component. The alumina has a primary particle shape of a square shape, an average primary particle diameter of 2 μm or less, and an α phase content rate. 1
Those having 0 to 80% are used. Alumina is not particularly limited as long as it satisfies the above requirements, for example,
Alumina obtained by calcining an alumina hydrate has a primary particle having a plate shape, a needle shape, or an angular shape (a shape in which the edge portion of the particle is angular) depending on the raw material and the manufacturing conditions thereof.
There are round shapes (rounded edges of particles) and the like, and the primary particles of alumina used in the present invention need to have a square shape.

The average primary particle size 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 small, and if it is too large, scratches and other roughness will occur on the polishing surface, which is not preferable. On the other hand, an alumina hydrate undergoes a dehydration reaction when heated, and finally becomes an α phase after passing through various intermediate phases such as γ, δ and θ phases, but the α phase content of alumina used in the present invention is 10%. Must be ~ 80%. If the α phase content is too low, the polishing rate will be low. Conversely, if it is too large, the polishing rate will be small. Preferred α
The phase content is 20-60%.

Incidentally, the alumina of the present invention may be in a state 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,
It is preferably 0.4 to 2 μm. If it is too small, the polishing rate will be low, and conversely, if it is too large, the polishing surface will become rough such as scratches.

Alumina used in the present invention is usually an alumina hydrate whose primary particles are angular (dibsite, bayerite, nostrandite, boehmite, etc.) and intermediate alumina (γ-alumina, δ-alumina, θ-). Alumina, etc.)
Is calcined while maintaining that the shape of the primary particles is angular and the α phase content in alumina is 10 to 80%. Calcination is usually about 1050
C. to about 1250.degree. C., preferably at a relatively low temperature.
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%.
%, Which is not preferable, in particular, the primary particles produced by hydrothermal treatment of gibbsite have angular boehmite,
Those calcined under 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 grain component. As the medium containing the abrasive grains, water, mineral oil, fatty oil, fat,
Fats, oils, waxes, metallic soaps, resins, alcohols and the like can be mentioned, but the abrasive composition of the present invention is particularly preferably an aqueous medium system, and when an aqueous medium is used, a semiconductor substrate, a magnetic memory hard disk, a laser. It is preferable because a good surface condition can be easily obtained in the precision polishing of materials such as parts. As the water-based polishing medium, a water-based polishing medium is usually used, but it is possible to include the additives described below within a range that does not impair the polishing performance.

The content of alumina in the polishing composition is usually 1 to 30% by weight, preferably 2 to 15% by weight. If it is too small, the polishing rate will be small, and if it is too large, uniform dispersion cannot be maintained. Further, when the composition is in a liquid state, the viscosity of the slurry becomes excessively large and the handling becomes difficult. It should be noted that such a concentration range is a preferred concentration range during actual polishing, and the polishing composition of the present invention can be used by preparing a stock solution having a relatively high concentration and diluting during actual polishing. Is.

Further, the abrasive composition of the present invention may contain various known additives for the purpose of promoting polishing and the like.
As the additive, for example, aluminum sulfate, aluminum nitrate, nickel sulfate, salts of inorganic acids or organic acids such as aluminum oxalate, ethylenediaminetetraacetic acid,
Of 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 belzene sulfonate, naphthalene sulfonic acid Examples thereof include surfactants such as formalin condensates, organic polyanion-based substances such as carboxymethyl cellulose salts and polyacrylic acid salts, celluloses such as cellulose and hydroxyethyl cellulose, and boehmite.

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

The abrasive composition of the present invention comprises metal, glass,
It is used for polishing plastics and the like, and 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 details of the reason that the highest polishing rate is exhibited when alumina has a specific α-phase content is unknown, but when the α-phase content is too small, polishing The polishing rate decreases because sufficient hardness and dispersibility cannot be obtained, and conversely, when the polishing rate is too large, the edge portion of the primary particles that were angular due to the progress of sintering is rounded, It is considered that another feature, that is, that the shape is not square, cannot be maintained, 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]

[Examples] Specific embodiments of the present invention will be described below with reference to Examples, but the present invention is not limited to the following Examples without departing from the scope of the invention. The physical properties of alumina used in the present invention were measured according to the methods described below.

Shape of primary particles: observed by electron micrograph (30,000 times). Average primary particle size: Each primary particle size (average of major axis and minor axis) is read from an electron micrograph and averaged (n
= 10), and the average primary particle diameter was used. α-phase content: An integrated intensity of the (113) plane diffraction line was obtained by X-ray diffraction measurement of alumina as a sample, and a calibration curve obtained by performing similar measurement in advance using alumina whose α-phase content was known , Α phase content was calculated.

Examples 1 to 4 [Production of Alumina] The gibbsite was hydrothermally treated in an autoclave at 200 ° C. for 4 hours, filtered and dried to obtain boehmite. This boehmite was 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 by a dry pulverizer to obtain 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. The physical properties of this alumina are shown in Table 1. As a representative of Examples 1 to 4, Example 2
FIG. 1 shows an electron micrograph (x30,000) of the alumina (b). Alumina (a), (c) and (d) of Examples 1, 3 and 4 also had the same shape.

[Preparation of Abrasive Composition] Alumina (a), (b), (c) and (d) obtained as described above was dispersed in water using a high speed mixer to obtain a slurry,
Further, diethylenetriaminepentaacetic acid pentasodium salt, aluminum sulfate and boehmite were added and mixed as polishing accelerators to prepare respective polishing agent compositions. On this occasion,
The ratio of each component was 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 polishing composition. It was made to be 5% by weight. As Boehmite, Condea Ch
emie's DISPERAL (registered trademark) was used.

[Polishing test] Electroless nickel-phosphorus plating (nickel 90
3.5-inch memory hard disk (alloy diameter 95 mm) with ~ 92%, phosphorus 10-8% alloy plating layer)
The substrate of was used. Double-sided polishing machine (surface plate diameter φ64
0 mm).

Suede type polishing pads (Domitex 25-3, manufactured by Daiichi Race Co., Ltd.) are used on the upper and lower surface plates of the polishing machine.
Was adhered, 5 disks were loaded, and polishing was performed for 3 minutes.
Polishing conditions are processing pressure of 125 g / cm ² and lower platen rotation speed 5
The rpm was 0 rpm, and the polishing agent supply rate was 150 cc / min. After polishing, the disc was washed and dried, and the polishing rate was calculated from the weight loss. The surface condition of the disc after polishing was observed and evaluated. For the surface observation, 5 using a differential interference microscope
0 to 400 times scratch, orange peel,
The presence or absence of pits and protrusions was observed. The test results are shown in Table-1.

Comparative Example 1 Alumina having the physical properties shown in Table 1 was prepared in the same manner as in Example 1 except that the calcination condition of boehmite was 1080 ° C. for 2 hours in the production of alumina of Example 1. e) was produced, an abrasive composition was prepared in the same manner as in Example 1, and a polishing test was conducted. The results are shown in Table-1.

Comparative Example 2 In the production of alumina of Example 1, the physical properties shown in Table 1 are the same as those of Example 1 except that the calcination conditions of boehmite are 1220 ° C. and 2 hours. ) Is produced and an abrasive composition is prepared in the same manner as in Example 1,
A polishing test was performed. The results are shown in Table-1.

Comparative Example 3 Alumina having the physical properties shown in Table 1 was prepared in the same manner as in Example 1 except that the calcination condition of boehmite was 1230 ° C. for 5 hours in the production of alumina of Example 1. g) was produced, a polishing composition was prepared in the same manner as in Example 1, and a polishing test was conducted. The results are shown in Table-1.

Comparative Example 4 In Example 1, as the alumina, hydrated alumina obtained by the hydrolysis method of organoaluminum was calcined at 1100 ° C. for 2 hours, pulverized by a dry pulverizer and sized. An abrasive composition was prepared in the same manner as in Example 1 except that alumina (h) having the physical properties shown in Table 1 was used, and a polishing test was conducted. The results are shown in Table-1.

Comparative Example 5 In Comparative Example 4, the calcination condition of hydrated alumina was 120.
The same procedure as in Comparative Example 4 was repeated except that the temperature was 0 ° C. for 2 hours.
Alumina (i) having the physical properties described in 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. An electron micrograph (30,000 times) of alumina of Comparative Example 5 is shown in FIG.

[0028]

[Table 1]

[0029]

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

[Brief description of drawings]

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

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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Ito 1 Fukuda-cho, Joetsu City, Niigata Prefecture Naoetsu Plant, Mitsubishi Kasei Co., Ltd. (72) Sumio Kojima 1 Fukuda-cho, Joetsu City, Niigata Prefecture Naoetsu Plant, Mitsubishi Kasei Co., Ltd. Within

Claims (3)

[Claims] 1. The shape of primary particles is angular, the average primary particle diameter is 2 μm or less, and the α phase content is 10 to 80%.
An abrasive composition containing alumina as an abrasive grain component. 2. The abrasive composition according to claim 1, wherein alumina is dispersed in an aqueous medium. 3. The abrasive composition according to claim 1, wherein the alumina is obtained by calcining boehmite produced by hydrothermal treatment of gibbsite.