JPH0419075A - Polishing tool - Google Patents

Abstract

PURPOSE:To prevent the surface of a workpiece to be polished from contamination by adding polymer-grafted ultrafine-grain microgel provided with a surface functional group so as to prevent a surface active agent, added for the purpose of preserving a polishing tape for a long period of time, from exuding to the surface. CONSTITUTION:Polishing paint containing abrasive powder and binding material is applied on a deflectable supporting body and dried to form a polishing layer. At this time, polymer-grafted ultrafine-grain microgel provided with a surface functional group is added thereto. The dispersion of the abrasive powder paint is thereby uniformed. In addition, since dispersant and lubricant serving as a surface active agent are not used, there is no problem of exudation even after a long period of preservation, so that the surface of a work piece to be polished is prevented from contamination, and also the paint film is prevented from being plasticized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polishing tool such as a polishing tape, and more particularly to a polishing tape suitable for precision polishing of electronic components such as magnetic heads and magnetic disks.

(Prior Art and its Problems) There is an increasing demand for more precise finished surfaces of electronic parts, etc., and as a result, the particle size of the abrasive powder used in polishing tools is required to be smaller and smaller. As abrasive particles become finer, their surface energy increases, making them more likely to aggregate, and if aggregated abrasive particles are applied to a support film to form an abrasive tool such as an abrasive tape. , causing damage to the surface of the object to be polished.

Traditionally, low-molecular dispersants such as surfactants have been used as dispersants for abrasive powder, but when abrasive tapes are stored for a long period of time, the added surfactant adjuvants ooze out to the surface (bleed). It adsorbs to the surface of the object to be polished, causing surface contamination and plasticization of the coating film.

(Objective of the Invention) An object of the present invention is to provide a polishing tool in which a polishing layer with good dispersibility is formed using finely divided abrasive powder.Another object of the present invention is to solve the problem of exudation. The purpose is to provide a polishing tool that does not have

(Means for Solving the Problems) The present invention provides a polishing tool in which a polishing layer is formed by coating a flexible support with a polishing paint containing an abrasive powder and a binder and drying the polishing layer. The object of the invention is achieved by an abrasive tool characterized by the addition of polymer-grafted ultrafine microgels having groups.

Since the polymer-grafted ultrafine microgel having a surface functional group used in the present invention is extremely fine, it has a large surface area and its viscoelasticity can be easily controlled.

This ultra-fine microgel has high affinity and compatibility with both the abrasive powder and the binder resin, resulting in uniform dispersion of the abrasive powder coating, and therefore the fine abrasive particles in the coating film applied to the support and dried. Powder agglomeration is prevented and smoothness is improved. The gel and binder resin phases also form a continuous layer in the coating, improving mechanical and physical properties, heat resistance, and abrasion resistance, thereby improving polishing performance and durability of the polishing tool. Furthermore, since no dispersant or lubricant such as a surfactant is used, there is no problem of oozing even after long-term storage, and there is no possibility of contaminating the surface of the object to be polished or plasticizing the coating film.

The resin constituting the microgel is selected from acrylic resin, polyester resin, and acrylic-polyester copolymer. In addition, the particle size of microgel is 0.02 to 0.5 μm.
If the zero particle diameter is larger than this, dispersibility will be inhibited. If the particle size is smaller than this, it is no longer a gel, and the intended effects of the present invention cannot be obtained.

Surface functional groups selected from acidic groups, basic groups, and/or polar groups are bonded to the surface of the microgel. These groups can be produced by grafting and polymerizing monomers having these groups onto acrylic resins, polyester resins, and acrylic-polyester copolymers. Examples of such monomers include those with acidic groups such as acrylic acid and methacrylic acid, those with hydroxyl groups such as those obtained by reacting dibasic acids such as maleic acid with lower alcohols, and basic monomers such as amines. There are some that have groups. These functional groups have an affinity for the abrasive powder. On the other hand, the resin constituting the main body of the gel has an affinity for and is compatible with the binder resin.

The amount of microgel added is 1 to 1 based on the solid content of the abrasive paint.
20% by weight, preferably 1-10! iii%. When the amount is less than this range, the dispersibility decreases. On the other hand, if it exceeds this range, it will gel.

Incidentally, conventionally known abrasive powders such as diamond, alumina, a-iron oxide, etc. can be used as the abrasive powder, and those having an average particle diameter of 1 μm or less can be used depending on the desired polishing accuracy. Further, as the binder, known binders such as thermoplastic, thermosetting, and electron beam curable resins can be used.

Example 1 The dispersion stability of abrasive powder by adding microgel was investigated. The composition of the abrasive paint was as follows: Abrasive (diamond) powder 40% by weight (average particle size 0.3 μm) Binder resin 45% by weight (polyester) Microgel 15% by weight (SGP-
154, manufactured by Nippon Paint) Average particle size: 80 nm Styrene-acrylic copolymer Non-volatile content: 20% by weight Functional group: Hydroxyl group The above formulations were thoroughly mixed, allowed to stand at room temperature, and the sedimentation volume of the abrasive powder was measured. For comparison, sedimentation was measured in the same manner using a sample without the addition of microgel. The results are shown in FIG.

As is clear from the figure, addition of microgel significantly improved dispersion stability.

Example 2 In this example, a polishing tool was produced using the following composition, and the coating film strength and surface texture were measured.

Abrasive material (alumina) powder 40% by weight (average particle size 0.4 μm) Binder resin N2304 40-60% by weight (Japan Polyurethane) Microgel 0-20% by weight (SGP
-154) Average particle size: 80% m Styrene-acrylic copolymer Non-volatile content: 20% by weight Functional group: Hydroxyl group The above formulation was thoroughly mixed to prepare an abrasive coating material, which was applied to a polyester film support. The purifying agent was removed by drying.

Final polishing of a magnetic head for a floppy disk was performed using a coating film containing 10% microgel at a tape speed of 40 m/7 min, and the finished surface was
The tape was observed using a 00x optical microscope to evaluate the scratch rate and durability of the tape. As a result, surface scratches (scratches larger than normal polishing streaks defined by particle size), which normally occur at around 0.3%, did not occur at all. The number of heads polished from 10 mm of polishing tape was increased by about 30%.

The strength of the coating film was also measured. The results are shown in Figure 2. The figure shows that the coating film strength improves as the amount of microgel added increases, and that the effect gradually becomes saturated when the amount exceeds about 10%. Therefore, there is no point in using more than about 20% by weight.

Example 3 In this example, a polishing tool was prepared using the following composition, and the coating film strength and surface texture were measured.

Abrasive (α iron oxide) powder 40% by weight (average particle size 0
2μm) Binder resin 40-60% by weight (polyvinyl chloride) Microgel 0-20% by weight Average particle diameter
80%m Styrene-acrylic copolymer non-volatile content 20% by weight Functional group Hydroxyl group A coating film containing 5% by weight of microgel was used to finish polish the ferrite head for 10 seconds, and the polished surface of the head was polished at 50% by weight.
The finished surface of the head and the durability of the tape were evaluated by observing with a 0x optical microscope. As a result, the number of heads that could be polished from 10 mm was increased by about 30% compared to the one without additives. Furthermore, when the coating film strength was measured, the results shown in Figure 3 were obtained.

It was found that the coating film strength becomes saturated when the amount of microgel added exceeds 10%.

Figure 3 is a graph showing the amount of microgel added and the strength of the polishing tape coating, and Figure 3 is a graph showing the amount of microgel added and the strength of the polishing tape coating using iron oxide powder.

[Brief explanation of drawings]

Figure 1 is a graph showing the dispersion stability of a diamond powder paint containing microgel and a paint without additives. Figure 2 is an engraving of a drawing for a coating film using alumina powder (no changes in content). ) to Tame i (wt%) My707') Shifunka111 (wt%) Procedure correction! (Canada) August 9, 1990 Name of invention Polishing tool Agent 〒103 Date of notification of amendment order July 31, 1990 Drawings subject to amendment

Claims (4)

[Claims] (1) In a polishing tool in which a polishing layer is formed by applying a polishing paint containing abrasive powder and a binder onto a flexible support and drying it, a polymer-grafted ultrafine microgel having a surface functional group is used. A polishing tool characterized by adding. (2) The polishing tool according to item 1 above, wherein the microgel has a particle size of 0.02 to 0.5 μm. (3) The polishing tool according to item 1 or 2, wherein the resin constituting the microgel is selected from acrylic resin, polyester resin, and acrylic-polyester copolymer. (4) The polishing tool according to any one of items 1 to 3, wherein the surface functional group is selected from acidic groups, basic groups, and polar groups.