JPH01121163A - Composition for polishing of aluminum magnetic disk - Google Patents

Abstract

PURPOSE:To favorably polish an aluminum substrate in a highly efficient manner without entailing any orange peels, projections and pits by using a specific abrasive accelerator for the end. CONSTITUTION:A composition for polishing an alkalescent aluminum magnetic disk is composed of water, abrasive powder and an abrasive accelerator consisting of triethanolamine carboxylic acid chloride and triethanolamine hydrochloride. This triethanolamine carboxylic acid chloride and triethanolamine hydrochloride serve as abrasive acceleration in addition to making a polishing surface into high accuracy, so that there is utterly nothing of any orange peels and, what is more, less in projections and pits, and thus such a highly accurate polishing surface that is small in waviness is securable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polishing composition for aluminum magnetic disks, which can rapidly polish aluminum magnetic disks to a high-precision mirror surface. More specifically, it relates to polishing compositions for aluminum substrates, nickel substrates that are electrolessly plated with nickel phosphorus on aluminum substrates, alumite substrates that are anodized aluminum substrates, etc. The present invention relates to a slightly alkaline polishing composition suitable for polishing substrates.

[Conventional technology]

The polishing composition conventionally used for aluminum magnetic disks is mainly an aqueous slurry in which alumina and an acidic polishing accelerator are suspended or dissolved in water.

JP-A-81-278587 discloses a weakly acidic polishing composition comprising alumina, nickel sulfate, and water.

Further, JP-A No. 62-25187 discloses a strongly acidic polishing composition comprising alumina, aluminum nitrate, etc., and water.

[Problem that the invention seeks to solve]

However, although these weakly acidic or strongly acidic polishing compositions exhibit good performance when polishing nickel substrates and alumite substrates, when polishing aluminum substrates, orange peel occurs, cloudiness occurs, and the finish is mirror-like. It cannot be used due to its quality. The quality required for aluminum substrates is basically the same as nickel substrates, etc., but due to the difference in material and hardness, orange peel and pits due to polished protrusions and falling off of intermetallic compounds occur. It is easy to do this, and the undulation also tends to become large.

The object of the present invention is to solve these problems by providing a polishing composition that does not require orange peel, has few protrusions and pits, can provide a highly accurate mirror surface with small waviness, and has high polishing efficiency. . Although the polishing composition according to the present invention is suitable for polishing aluminum substrates, there is no problem in using it for polishing nickel substrates or alumite substrates.

[Means for solving problems]

The present inventors used alkaline polishing accelerators in polishing aluminum substrates, in view of the fact that conventional acidic polishing accelerators do not produce mirror surfaces because orange peel and oxide films are formed due to the reaction between aluminum substrates and acidic compounds. We focused on polishing accelerators. However, since the reaction is too strong with alkali metal hydroxides such as sodium hydroxide, when various amine compounds were added to alumina and aluminum substrates were polished, triethanolamine carboxylate and triethanolamine hydrochloride were used. The present invention was completed based on the discovery that a combination of salts has a high polishing accelerating effect and that a highly precisely polished surface can be obtained.

That is, the present invention is an aluminum magnetic disk polishing composition comprising alumina abrasive powder, triethanolamine carboxylate, triethanolamine hydrochloride, and water.

The present invention will be described in detail below.

The alumina abrasive powder is preferably α-Aρ203 or the like and has an average particle diameter of 0.5 to IO μm. Triethanolamine carboxylate is HN(CH2CH20H)3・RC
Represented by OO- (R is a hydrocarbon group), triethanolamine hydrochloride is HN(CH2CH20H)3.c, l?
It is represented by -. The ratio of triethanol carboxylate to triethanol hydrochloride is arbitrary, but in order to increase the polishing speed and suppress the generation of protrusions and pits, the ratio of triethanolamine carboxylate should be 50% by weight to 9% by weight.
0% by weight is preferred.

The polishing composition of the present invention is a suspension of alumina abrasive powder in an aqueous solution of triethanolamine carboxylate and triethanolamine hydrochloride, and the preferred composition is 1 to 25% by weight of alumina abrasive powder, triethanolamine It is a weakly alkaline slurry containing 0.1 to 5% by weight of amine carboxylate and triethanolamine hydrochloride in total. or,
It is also possible to adjust the pH by adding soda carbonate or the like.

The preferred pH is 9.0 to 10.0. In particular, soda carbonate is very useful as it has the effect of increasing the polishing speed and suppressing the formation of protrusions and pits. The preferable addition amount is 0.
01 to 0.05% by weight.

Furthermore, in actual polishing, this polishing composition can be used not only in its original form, but also optionally diluted to about 2 to 6 times. The concentration of the polishing accelerator is preferably 0.1% by weight or more in order to increase polishing efficiency and reduce the occurrence of protrusions and pits. Moreover, if it exceeds 5% by weight, the polishing rate will decrease and pits will be more likely to occur, so it is preferably 5% by weight or less. In actual use, it is 0.1 to 1% by weight.
is most preferred.

When the amount of alumina abrasive powder is less than 1% by weight, polishing efficiency decreases and scratches occur, and even when it exceeds 25% by weight, no improvement in polishing efficiency is observed and the viscosity increases, resulting in poor workability. Therefore, the content is preferably 1 to 25% by weight. If the average particle size of the alumina abrasive powder is less than 0.5 μm, the polishing efficiency will be low, and if it exceeds 10 μm, the surface roughness will become rough, so it is preferably 0.5 to 10 μm.

In the present invention, triethanolamine carboxylate and triethanolamine hydrochloride have the function of accelerating polishing and making the polished surface highly precise.There is no occurrence of orange beer, there are few protrusions and pits, and there is high precision with small waviness. This makes it possible to quickly obtain a polished surface. Furthermore, the corrosivity of the machine,
It is also characterized by low toxicity to the human body.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. The polishing properties in the following examples were evaluated by the following polishing test. For polishing, a 4-way type double-sided polishing machine (surface plate diameter φ840 mm) was used, and the surface plate was equipped with a suede type pad (S P D manufactured by Showa Polishing System).
No. 4235) and polished ten 3.5-inch aluminum substrates for 6 minutes. The polishing conditions were lower surface plate rotation speed: 70 rpm.

Processing pressure crab 100g/at Slurry supply amount: 10
0 ml/n+in. After polishing, the aluminum substrate is weighed and the polishing speed is determined from the weight loss. In addition, the surface is observed using a differential interference microscope and a 100,000 lux spot light to determine the degree of protrusions, pits, scratches, etc. or. The surface roughness is measured using Talystep and Talydata 2000 manufactured by Rank Taylor Hobson.

Examples 1 to 5 Triethanolamine acetate and triethanolamine hydrochloride were added to a slurry containing 22% by weight of alumina powder with an average particle size of 1.9 μm, keeping the ratio of the former at 82% by weight. The total proportion of both in the composition is 0.425. 1.275. 2.125°3.400
, and 4.250% by weight, and then add 0.15 to 0.30% by weight of soda carbonate to adjust the pH to 9.
8 to obtain a polishing composition of the present invention. This polishing composition was diluted with water to a volume ratio of 4 times, and an aluminum substrate polishing test was conducted. The test results are shown in Table 1.

(Left below) Table 1 The qualities normally required for aluminum substrates are surface roughness (Rt+n) of 2.000 Å or less, waviness (
vt) is 700 Å or less, but according to Table 1, all surfaces polished by the polishing composition of the present invention are significantly below this value. Of course, no orange peel was observed at all.

Further, the straightness is required to be 5 μm/25+nm in length or less, and the outer peripheral surface sag is required to be 0.5 μm/4 mm in length or less, and for this purpose, the polishing rate is preferably 0.8 μm/min or more. The polishing speed with the polishing composition of the present invention exceeded this value, and the polished surface was very excellent, with straightness of 0.12 μm and length of 725 mm, and outer peripheral surface sagging of 0.13 μm/4 mm in length. However, when the concentration of the polishing accelerator was 0.1% by weight or less and 1.0% by weight or more, some pitting was observed, so the optimum concentration of the polishing accelerator is 0.1 to 1% by weight.
It is 0% by weight.

〔effect〕

The polishing composition using a polishing accelerator combining triethanolamine carboxylate and triethanol hydrochloride according to the present invention is particularly effective for polishing aluminum substrates, and has the following features: 1) High polishing efficiency 2) Orange No peeling 3) Few protrusions and pits 4) Low surface roughness 5) Excellent surface straightness and minimal sagging on the outer periphery 6) Less corrosive to machinery 7) It is also effective in that it is less harmful to the human body.

Claims (3)

[Claims] (1) A weakly alkaline aluminum magnetic disk polishing composition comprising water, alumina abrasive powder, and polishing accelerators of triethanolamine carboxylate and triethanolamine hydrochloride. (2) The proportion of the polishing accelerator in the composition is 0.1 to 5.
% by weight of the aluminum magnetic disk polishing composition according to claim 1. (3) The proportion of alumina abrasive powder in the composition is 1
25% by weight and an average particle size of 0.5 to 10 μm.