JPH06179174A - Polishing body - Google Patents

Abstract

PURPOSE:To provide a polishing body (polishing tape) which prevents a magnetic head surface from being damaged and whose contact strength for the a magnetic head is uniform over the whole surface of the magnetic head. CONSTITUTION:The average particle diameter of a polishing agent 16 contained in a polishing layer 14 is formed to the nearly equal dimension to the thickness of the polishing layer 14. Accordingly, the generation of the unevenness on the surface of the polishing layer due to the coagulation of the polishing agent 16 is suppressed to the min., and the surface of the polishing layer 14 is formed nearly parallel to the surface of a flexible supporting body 12, and the surface of the polishing layer is smoothened. Further, a fine particle containing layer 18 is formed between the polishing layer 14 and the flexible supporting body 12. Accordingly, even if the particle diameter of the polishing agent 16 disperses a little, the surface of the polishing layer can be kept in nearly parallel to the surface of the flexible supporting body by allowing the lower part of the polishing agent 16 to intrude into the fine particle containing layer 18 in the formation of the polishing layer. Further, the polishing agent 16 is supported with elasticity by forming the fine particle containing layer 18, and the supporting strength for the polishing agent 16 is secured by the fine particles 20 in the fine particle containing layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing body such as a polishing tape for polishing an object to be polished such as a magnetic head of a magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art In order for a magnetic recording / reproducing apparatus to fully exhibit its recording / reproducing function, it is essential to ensure the smoothness of the surface of a magnetic head. For this reason,
For example, as disclosed in Japanese Unexamined Patent Publication No. 62-92205, a treatment of polishing a magnetic head by bringing a polishing body (polishing tape in this case) into contact with the surface of the magnetic head to travel.

In recent years, in order to improve the performance of a magnetic head, various materials and hardnesses (for example, soft magnetic material) have been adopted as a magnetic material in order to improve the performance of a magnetic recording head. In addition, a composite type magnetic head in which a plurality of magnetic materials having different materials and hardness are combined has been adopted as its structure.

[0004]

When polishing is performed on such a high-density magnetic recording type magnetic head using the above-mentioned conventional polishing body as it is, the unevenness on the surface of the polishing layer is the magnetic head. The problem arises that the surface is scratched in a streak pattern. Although such a problem has occurred even when polishing a conventional magnetic head, it has become more prominent with the adoption of a magnetic head compatible with high-density magnetic recording. Particularly for the above-mentioned composite type magnetic head, if the strength of contact of the polishing body with respect to the magnetic head is not uniform over the entire surface of the magnetic head, the degree of polishing will vary depending on the part, and the polishing surface will be different. There is a problem that there is a step on the bottom.

Therefore, in response to the above-mentioned trend of magnetic head development, a polishing body for polishing the magnetic head has also been required to be capable of precisely polishing the magnetic head.

Such a request is not limited to the magnetic head,
It also exists for general objects to be polished that require precise polishing.

The present invention has been made in view of the above circumstances, and has a uniform strength of hitting an object to be polished over the entire surface to be polished and does not damage the surface to be polished. It is intended to provide the body.

[0008]

A polishing body according to the present invention comprises:
The above object is achieved by devising the particle size of the abrasive in the polishing layer and further providing a fine particle-containing layer below the polishing layer.

That is, as shown in FIG. 1, in a polishing body (10) in which a polishing layer (14) is provided on the surface of a flexible support (12), it is contained in the polishing layer (14). The average particle diameter of the polishing agent (16) present is the polishing layer (14)
And the thickness of the polishing layer (14).
Between the flexible support (12) and the fine particle-containing layer (1
8) is provided.

The above-mentioned "polishing body" is not limited to a tape-shaped (polishing tape) as long as it can be ground by contact with an object to be polished, and it is a disk-shaped (polishing disk). It is a concept that also includes etc. In the case of a polishing tape, polishing can be performed by, for example, running the polishing tape from the sending section through the object to be polished to the winding section, and in the case of a polishing disk, rotating the polishing disk, for example. Can be polished.

Examples of the above-mentioned "flexible support" include:
Polyethylene terephthalate (PET), polyethylene naphthalate, polyethylene-2,6-naphthalate,
It can be selected from a film or sheet made of a synthetic resin such as polypropylene, polycarbonate, polyethylene, polyamide, polyamideimide, polyimide, polysulfone, or polyethersulfone.

The above-mentioned "polishing layer" may be a composition of the polishing agent or a polishing layer other than the polishing agent as long as it contains a polishing agent having an average particle diameter substantially the same as the thickness of the polishing layer. The components (binder, additive, etc.) contained are not particularly limited.

The "average particle size of the abrasive" is 1.5 to
0.05 [mu] m is desirable, and more desirably 1.0-0.
It is 08 μm. If the average particle diameter of the polishing agent is too large, the surface of the magnetic head or the like, which is the object to be polished, will be scratched, and in particular, finish polishing of the video magnetic head will be impossible. Further, if the average particle diameter of the abrasive is too small, the polishing power will be reduced, which is not desirable.

The "average particle size of the abrasive" is calculated by, for example, measuring the size of 500 particles arbitrarily extracted with a transmission electron microscope photograph of 100,000 times and calculating the average value. Can be done by.

The phrase "the average particle size of the polishing agent is approximately the same as the thickness of the polishing layer" means that the thickness of the polishing layer is within 2.5σ of the particle size distribution of the polishing agent. However, it is desirable that the size is within 2.0σ.

Examples of the above-mentioned "polishing agent" include α-alumina, γ-alumina, fused alumina, silicon carbide, chromium oxide, cerium oxide, corundum, diamond and α.
There are iron oxide, emery (main components: corundum and magnetite), garnet, silica stone, silicon nitride, boron nitride, etc., mainly having a Mohs hardness of 6 or more, more preferably 7 or more, most preferably 9 or more. Of these, one or more types can be used in combination.

As the binder, various resins known in the art can be used. These resins can be used alone or in combination of two or more, and examples thereof include thermoplastic resins, thermosetting resins, and reactive resins.

The above-mentioned thermoplastic resin has a softening temperature of 1
50 ° C. or less, average molecular weight 10,000 to 300,000
0, having a degree of polymerization of about 50 to 2,000, for example, a polymer such as (meth) acrylic acid ester, (meth) acrylonitrile, butadiene, vinyl ester, (meth) acrylamide, vinyl chloride, vinylidene chloride, or the like. Polymers of these derivatives, or polymers or polymers with monomers copolymerizable therewith, such as vinyl chloride vinyl acetate copolymer, vinyl chloride copolymer, vinylidene chloride vinyl chloride copolymer, vinyl acrylonitrile chloride Copolymer, acrylic ester acrylonitrile copolymer, acrylic ester vinylidene chloride copolymer, acrylic ester styrene copolymer, methacrylic ester acrylonitrile copolymer, methacrylic acid vinylidene chloride copolymer, methacrylic ester styrene Copolymer, Tan elastomer, nylon -
Silicone resin, nitrocellulose-polyamide resin,
Polyfukka vinyl, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, ethyl cellulose, (Methyl cellulose, propyl cellulose, methyl ethyl cellulose, carboxymethyl cellulose, acetyl cellulose, etc.), styrene butadiene copolymer, polyester resin, chlorovinyl ether acrylate copolymer, amino resin, various synthetic rubber thermoplastic resins and mixtures thereof. Etc. can be used.

The above-mentioned thermosetting resin or reactive resin has a molecular weight of 200,000 or less in the state of a coating liquid, and can be subjected to reactions such as condensation and addition by heating after coating and drying. is there. Specifically, for example, phenol resin, phenoxy resin, epoxy resin,
Polyurethane curable resin, urea resin, melamine resin, alkyd resin, silicone resin, acrylic reaction resin,
Epoxy-polyamide resin, nitrocellulose melamine resin, mixture of high molecular weight polyester resin and isocyanate prepolymer, mixture of methacrylate copolymer and diisocyanate prepolymer, mixture of polyester polyol and polyisocyanate, urea formaldehyde resin, low molecular weight glycol / High molecular weight diol / triphenylmethane triisocyanate mixtures, polyamine resins, polyimine resins and mixtures thereof.

It is also possible to use a known electron beam curable resin. These examples and the manufacturing method thereof are described in detail in JP-A-62-256219.

For these thermoplastic resins, thermosetting resins, and reactive resins, it is desirable to use at least those having the polar groups listed below in addition to the main functional groups. In the present invention, these resins are used. It is preferable to use a polar group-containing resin in order to enhance the interaction between the compound and the abrasive particles, improve the dispersibility, and interact with the compound of the present invention to form an integrated polishing layer. As the polar group, a carboxylic acid group, a sulfenic acid group, a sulfonic acid group, a phosphoric acid group, a sulfuric acid group, a phosphone group, a phosphine group, a boric acid group,
Acidic groups such as sulfuric acid ester groups, phosphoric acid ester groups, and alkyl ester groups thereof (these acidic groups may be in the form of Na salts, etc.); amino acid groups; aminosulfonic acid groups, aminoalcohol sulfuric acid or phosphoric acid esters Group; amphoteric group such as alkylbetaine type; basic group such as amino group, imino group, imide group, amide group; epoxy group, hydroxyl group, alkoxyl group which produces a hydroxyl group by reaction,
Usually contains 1 to 6 types of thiol group, halogen group, silyl group, siloxy acid group, etc., and 1 × 10 ⁻⁶ per 1 g of resin
It is desirable that the content of ˜1 × 10 ⁻² equivalent / g is included. Particularly desirable polar groups include an epoxy group, a —SO ₃ M group and the like (where M is H or an alkali metal such as Na or K, or an ammonium ion). These polar groups can be introduced into the resin by copolymerizing (cocondensation polymerization) a monomer containing a polar group or by utilizing a polymer reaction.

As the polar group-containing resin, vinyl chloride resin and polyurethane resin are particularly desirable. Particularly, the polar group is preferably an epoxy group or a —SO ₃ M group.

The above vinyl chloride resin is preferably an epoxy group-containing vinyl chloride copolymer, and includes a vinyl chloride repeating unit, an epoxy group-containing repeating unit, and -SO ₃ M (M is the same as above and particularly Vinyl chloride-based copolymer containing a repeating unit having Na).

The polar group content of the polar group-containing resin is 1
The range of × 10 ^-6 to 1 × 10 ^-2 equivalent / g is desirable. More preferably, it is 1 × 10 ⁻⁶ to 1 × 10 ⁻² equivalent / g. The molecular weight is preferably 10,000 to 200,000.

The above-mentioned polar group-containing polyurethane resin is specifically a polyol such as polyether diol, polyester diol, polycarbonate diol, polycaprolactone diol and diisocyanate, and if necessary, a polyhydric alcohol, an aliphatic polyamine and a fat. It can be prepared from a chain extender such as a cyclic polyamine or an aromatic polyamine, and the polar group can be introduced using various means. For example, it can be obtained by introducing a polar group into a polyester polyol using a polybasic acid or a polyol having a polar group and reacting the polyester polyol with a polyisocyanate compound. This polyisocyanate compound can be used not only as a component of the polyurethane resin but also as a curing agent for forming a three-dimensional network structure of the resin. Further, in the present invention, any curing agent can be used.

In the present invention, an abrasive, a binder and the like are dispersed, kneaded,
The organic solvent used for coating may be mixed and used in any ratio. A specific example is shown below.
Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones; methanol, ethanol, butanol and other alcohols; methyl acetate,
Esters such as ethyl acetate, butyl acetate, ethyl lactate, glycol monoethyl ether acetate; glycol ethers such as ether, glycol dimethyl ether, glycol monoethyl ether, dioxane; tars such as benzene, toluene, cresol, chlorobenzene, styrene (Aromatic hydrocarbon); methylene chloride, ethylene chloride, carbon tetrachloride, chloroform,
Chlorinated hydrocarbons such as ethylene chlorohydrin and dichlorobenzene, N, N-dimethylformaldehyde, hexane and the like can be used.

The polishing layer of the present invention may contain a lubricant, a dispersant, an antistatic agent and the like as additives in addition to the above organic solvent.

The method of dispersion and mixing in the preparation of the polishing layer-forming coating material comprising the polishing agent, the binder, the organic solvent, the additive, etc. of the present invention is arbitrary, and conventionally known methods can be applied. For example, the paint can be divided into several compositions and mixed later. Various kneaders are used for kneading and dispersing. For example, two roll mill, three roll mill,
Ball mill, pebble mill, tron mill, sand grinder, segvari, attritor,
A high speed impeller disperser, a high speed stone mill, a high speed impact mill, a disper, a kneader, a high speed mixer, a homogenizer, an ultrasonic disperser and the like can be used.

The fine particles contained in the above-mentioned "fine particle-containing layer" may of course be an abrasive, but various inorganic powders and resin powders other than the abrasive can be used. For example, SnO ₂ , SiO ₂ , Fe ₂ O ₃ , Fe ₃ O ₄ ,
TiO ₂ , GeO ₂ , ZrO ₂ , CaCO ₃ , Zn
_{O 2, Al 2 O 3 ·} 4SiO 2 · H 2 O ( pyrophyllite _{clay), Al 2 O 3 · 2SiO} 2 · 2H 2 O ( kaolin clay), various inorganic powders, polyethylene particles such as barium sulfate, acrylic resin Various resin powders such as the above fine particles and Teflon fine particles can be mentioned.

The thickness of the "fine particle-containing layer" and the particle diameter of the fine particles contained therein are not particularly limited, but it is preferable that the thickness of the fine particle-containing layer is larger than the thickness of the polishing layer. Further, it is preferable that the particle size of the contained fine particles is smaller than the particle size of the abrasive, because the cushioning effect (which will be described later) becomes large. Further, if the particle diameter of the contained fine particles is made smaller, the rigidity of the fine particle-containing layer itself becomes stronger and the polishing power of the polishing tape as a whole is improved. From this point of view, the particle diameter of the fine particles contained in the “fine particle-containing layer” is 1.
The thickness is preferably 0 to 0.01 μm, and more preferably 0.5 to 0.05 μm.

In this case, the relationship between the average particle diameter B of the abrasive particles in the "polishing layer" and the average particle diameter A of the fine particles in the "fine particle-containing layer" is such that A / B is 0.7 or less, preferably 0. ．
It is 6 or less, particularly preferably 0.4 or less. If A / B becomes too large, the cushioning effect of the fine particle-containing layer will be insufficient, and the irregularities of the fine particle-containing layer below the polishing layer will affect the surface properties of the polishing layer, and precise polishing will be sufficient. It is not preferable because it will disappear.

The components (binders, additives, etc.) other than the "fine particles" of the "fine particle-containing layer" are not particularly limited. For example, the same component as that of the polishing layer can be used. In particular, in order to obtain the cushioning effect of the fine particle-containing layer, it is desirable to use polyurethane resin or synthetic rubber resin as the binder resin.

As a method for forming the polishing layer and the fine particle-containing layer on the flexible support, a conventionally known method can be used. For details, refer to “Coating Engineering” (Asakura Shoten, 1972) or “Latest”. Coating technology / enlarged edition "(Comprehensive Technology Center Co., Ltd., 1984), etc., but it is possible to apply the polishing layer while the coating layer (fine particle-containing layer) is in a wet state. A so-called wet-on-wet coating method in which the liquid is applied is preferable.

As a concrete coating method, for example,
(1) The lower layer (fine particle-containing layer) is first coated by a gravure coating, roll coating, blade coating, extrusion coating device, etc.
-46186, JP-A-60-238179 and JP-A-2-265672, a method of applying an upper layer (polishing layer) by a support pressure type extrusion coating apparatus, (2) 63-88080
Japanese Patent Application Laid-Open No. 2-17971, Japanese Patent Application Laid-Open No. 2-26
A method of coating the upper layer and the lower layer substantially at the same time by one coating head having two slits for passing the coating liquid therein as disclosed in Japanese Patent No. 5672, (3) JP-A-2-174
The method of applying the upper layer and the lower layer almost at the same time by the extrusion coating device with a backup roll disclosed in Japanese Patent No. 965 can be adopted.

[0035]

OPERATION AND EFFECT OF THE INVENTION As in the conventional example shown in FIG.
If the average particle size of the abrasive (16 ') contained in the abrasive layer (14') is small, the abrasive (16 ') aggregates and the surface of the abrasive layer (14') has irregularities more than necessary. In the present invention, as shown in FIG. 1, the average particle size of the polishing agent (16) contained in the polishing layer (14) is approximately the same as the thickness of the polishing layer (14). Therefore, it is possible to minimize the occurrence of irregularities on the surface of the polishing layer (14) due to the agglomeration of the polishing agent (16), and moreover, the polishing layer (14)
Can be formed substantially parallel to the surface of the flexible support (12), whereby the surface of the polishing layer (14) can be smoothed.

Further, in the present invention, the polishing layer (1
4) and the flexible support (12) between the fine particle-containing layer (1)
Since 8) is provided, even if the particle size of the abrasive (16) contained in the abrasive layer (14) varies to some extent, when the abrasive layer (14) is formed, By inserting the lower part into the fine particle-containing layer (18), the surface of the polishing layer (14) can be maintained substantially parallel to the surface of the flexible support (12). In addition, the fine particle-containing layer (1
8) makes it possible to elastically support the abrasive (16) contained in the polishing layer (14), so that the fine particle-containing layer (18) is abraded by the polishing body (10). It can function as a cushion layer when it comes into contact with. Moreover, at that time, the fine particle-containing layer (1
Supporting strength for the abrasive (16) can be secured by the fine particles (20) in 8).

Therefore, according to the present invention, it is possible to obtain a polishing body in which the contact strength against the object to be polished is uniform over the entire surface to be polished and there is no fear of damaging the surface to be polished. And thereby, the to-be-polished material which has a to-be-polished surface which is smooth and has no damage can be obtained. Particularly when the object to be polished is a magnetic head, even if this is a magnetic head compatible with high-density magnetic recording, sufficient magnetic head output can be secured and dropout can be reduced.

In the present invention, the fine particle-containing layer is provided between the polishing layer and the flexible support, but a new layer is further provided between the fine particle-containing layer and the flexible support. It may be provided, and by doing so, the cushioning effect on the abrasive can be enhanced, and a more remarkable effect can be obtained. Further, the new layer may be provided for the purpose of improving the adhesive force between the layers.

[0039]

EXAMPLES Examples of the polishing tape according to the present invention will be described below. The "parts" shown below are all parts by weight.

Example 1 A coating solution for forming a polishing layer having the composition shown in Table 1 was applied on a polyethylene terephthalate (PET) support having a thickness of 50 μm by an extrusion method (wet simultaneous multilayer coating method) and dried. Then, it was slit into a width of 1 inch to prepare a polishing tape sample.

<Composition of polishing coating liquid> Abrasive agent: 300 parts Vinyl chloride / vinyl acetate copolymer resin: 20 parts Polyamide resin: 30 parts Epoxy resin: 7 parts Solvent: 320 parts

[0042]

[Table 1]

A magnetic floppy disk was subjected to a polishing treatment (burnishing treatment) using the above-mentioned various polishing tapes and a commercially available burnishing polishing machine manufactured by Hitec Seiko.

After the polishing treatment, it was incorporated into a 3.5-inch floppy cartridge to examine the slice dependency of dropout. We focused on the number of dropouts at a slice level of 65%, which is a particularly severe condition.

As a result, as shown in Table 1, the dropout number at the slice level of 65% became the minimum value when the thickness of the upper layer became a value close to the average particle diameter of the abrasive.

Example 2 A coating solution for forming a polishing layer prepared by the composition shown in Table 2 was applied onto a polyethylene terephthalate (PET) support having a thickness of 10 μm by an extrusion method and dried, and then a width of 1/2 inch was obtained. Slitting was performed to prepare a polishing tape sample.

Sample No. No. 8 was calendered after coating.

<Polishing liquid composition> Abrasive agent: 300 parts Vinyl chloride / vinyl acetate copolymer resin: 20 parts Polyamide resin: 30 parts Epoxy resin: 7 parts Solvent: 320 parts

[0049]

[Table 2]

8 mm VTR using the above-mentioned various polishing tapes and a commercially available high-tech Seiko varnish polishing machine
After polishing the application head, the output of the video head was obtained.

As a result, as shown in Table 2, the output increased as the thickness of the upper layer became closer to the average size of the abrasive particles contained in the upper layer. In this case, the sample N
o. As shown in the results of No. 8, extremely high output could be obtained when combined with calendering.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a polishing body according to the present invention.

FIG. 2 is a sectional view showing a conventional polishing body.

[Explanation of symbols]

 10 Abrasive body 12 Flexible support 14 Polishing layer 16 Abrasive agent 18 Fine particle-containing layer 20 Fine particle

Claims (1)

[Claims] 1. A polishing body in which a polishing layer is provided on the surface of a flexible support, wherein the average particle size of the polishing agent contained in the polishing layer is substantially the same as the thickness of the polishing layer. And a fine particle-containing layer provided between the polishing layer and the flexible support.