JP2527367B2 - Polishing tape - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polishing tape used for polishing a magnetic head or the like, and more particularly to a rough polishing tape.

(Prior Art) Magnetic heads for video tape recorders and high-end audio decks have a polishing layer coated by applying an abrasive coating solution containing an abrasive, a binder, an additive, etc. onto a flexible support and drying it. It is manufactured by polishing with the formed polishing tape.

Generally, such a polishing tape travels between two reels sandwiching a magnetic head, contacts the surface to be polished, and polishes the surface to be polished. Since the polishing tape has a flexible support, it is more suitable for polishing curved surfaces such as magnetic heads, etc. than a polishing grindstone. Also, since the specific polishing surface has few scratches and can be precisely polished, it is possible to finish polishing. Is essential to.

The polishing of the magnetic head with the polishing tape includes a rough polishing step for forming the tip shape of the magnetic head as well known,
A final polishing step for smoothly finishing the surface of the magnetic head. In each polishing step, a rough polishing tape and a finish polishing tape suitable for the purpose are used.
As a tape for finish polishing, for example, Japanese Patent Publication No.
An abrasive tape as disclosed in Japanese Patent Publication No. 62-10782 is used.

(Problems to be Solved by the Invention) The properties required for a rough polishing tape used to form the tip shape of a magnetic head are high polishing ability and the tip shape of the magnetic head is completed in a short time. It is possible to leave no deep scratches on the surface of the magnetic head after rough polishing.

If the rough polishing ability is low, the polishing time will be long and the productivity will be poor. If deep scratches remain on the surface of the magnetic head after the rough polishing, it takes a long time to remove the deep scratches in the subsequent final polishing step, and there is a problem that productivity is deteriorated. Furthermore,
Not only the productivity in the rough polishing step and the finish polishing step deteriorates, but also the amount of the polishing tape used in each step increases and the economical load increases.

In order to increase the polishing ability, the particle size of the polishing agent in the polishing layer may be increased. On the other hand, in order not to leave deep scratches on the surface of the magnetic head after rough polishing, the polishing agent in the polishing layer is required. It is better to reduce the particle size. Therefore, the above two characteristics are in a contradictory relationship, and either one of them has to be sacrificed, or a rough polishing tape that has an intermediate characteristic must be used.
It was not possible to obtain a rough polishing tape having sufficient characteristics simply by controlling the particle size of the abrasive.

In Japanese Patent Publication No. 62-10782, a hard Cr ₂ O ₃ abrasive,
A method of improving the smoothness of the magnetic head surface by mixing a soft α-Fe ₂ O ₃ abrasive has been proposed. However, this method is not suitable as a rough polishing tape because the polishing ability is significantly reduced by the soft α-Fe ₂ O ₃ abrasive.

The present invention has been made in view of the above problems,
An object of the present invention is to provide a polishing tape for rough polishing, which has high polishing ability and does not leave deep scratches on the surface to be polished.

(Means and Actions for Solving the Problems) The above object of the present invention is to provide a polishing tape having a polishing layer mainly composed of an abrasive and a binder formed on a flexible support. A first abrasive having an average particle diameter of 4 to 8 μm and a Mohs hardness of 8 or more and having a curved surface, and 2 having an average particle diameter of 6 to 9 μm and a Mohs hardness of 8 or more on the surface.
The above-mentioned flat surface is composed of a second abrasive having an angular shape, and the first abrasive is used with respect to the total amount of the first abrasive and the second abrasive.
5 to 30% by weight of the above abrasive, and as the binder, a vinyl chloride resin containing an epoxy group and a sulfonic acid group, a polyurethane resin containing a sulfonic acid group, and ethylene glycol, neopentyl glycol, phthalic acid, adipic acid Containing at least one of the saturated thermoplastic polyester resins containing as a main component, and containing polyisocyanate as a curing agent component, and the amount of the binder with respect to the total amount of the first abrasive and the second abrasive. Achieved with an abrasive tape characterized in that it is 10 to 50% by weight.

In the polishing tape of the present invention, the average particle size is 6 to
9 μm, Mohs hardness is 8 or more, and the surface is composed of two or more planes, that is, the second abrasive composed of angular particles having an angle increases polishing ability, and
The first abrasive composed of round-shaped particles having an average particle diameter of 4 to 8 μm and a Mohs hardness of 8 or more has a curved surface, and prevents deep scratches on the surface to be polished without significantly lowering the polishing ability. It

The second abrasive is a relatively angular particle having a surface having an angle formed by intersecting two planes obtained by crushing a raw material ingot (for example, WA # 2000 manufactured by Fujimi Abrasives Co., Ltd.). ). On the other hand, the round-shaped first abrasive having a curved surface is, for example, an abrasive obtained by a method of firing aluminum hydroxide formed by hydrolyzing organic aluminum (for example, Sumitomo Chemical Co., Ltd. CAH-3020 manufactured by the company) is a particle whose surface is entirely curved.

That is, since the second abrasive is hard and has a square shape, it has a high polishing ability. On the other hand, the first abrasive has a round shape with no corners on the surface of the particles, so that the second abrasive is It is considered to have the effect of flattening the deep scratches that were made.

Further, by making the first abrasive hard with a Mohs hardness of 8 or more, the deterioration of the polishing ability can be suppressed only slightly.

Further, the amount of the first abrasive is mixed in an amount of 5 to 30% by weight with respect to the total amount of the first abrasive and the second abrasive. 5% by weight
If it is less than 30%, the effect of preventing deep scratches on the surface to be polished is small, and if it exceeds 30% by weight, the polishing ability is slightly lowered.

The first abrasive and the second abrasive are specifically hard particles having a Mohs hardness of 8 or more, such as Cr ₂ O ₃ , Al ₂ O ₃ , SiC, and diamond.

The compounding amount of the binder constituting the polishing layer of the polishing tape of the present invention is 10 to 50% by weight, more preferably 15% by weight, based on the total amount of the first and second abrasives. ~
It is in the range of 20% by weight. If the amount is less than 10% by weight, the amount of the binder is insufficient, so that the abrasive particles come off from the polishing layer, which is not preferable. Further, when the coating solution of the composition for the polishing layer is applied by the doctor coat method, it is difficult to apply it uniformly, and coating streaks are likely to occur, resulting in lack of manufacturing stability. On the other hand, if the amount of the binder exceeds 50% by weight, the abrasive particles will be embedded in the binder and the polishing ability will not be sufficiently exhibited. When the amount of the binder is smaller than the amount of the abrasive, deep scratches are less likely to be formed, and when the amount is larger, the deep scratches tend to be formed, but within the above range, there is no practical problem.

Furthermore, as the binder, an epoxy group- and sulfonic acid group-containing vinyl chloride resin, a sulfonic acid group-containing polyurethane resin, and a saturated thermoplastic polyester resin containing ethylene glycol, neopentyl glycol, phthalic acid, and adipic acid as main components A system using at least one of them and polyisocyanate as a curing agent component improves the dispersibility of the abrasive particles and the durability of the polishing layer.

By the combined effect of the abrasive composition and the binder composition in the polishing tape of the present invention, it is possible to simultaneously satisfy the high polishing ability and the performance of preventing deep scratches on the surface to be polished,
It can be applied not only to rough polishing tapes, but also to intermediate finish polishing tapes and finish polishing tapes. In the case of intermediate finish polishing tapes and finish polishing tapes, polishing with an appropriate average particle size is possible. The agent particles may be selected.

Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a schematic view of a polishing apparatus using the polishing tape of the present invention.

The polishing tape 1 is delivered from the tape delivery reel 6 in the direction of the arrow in the drawing as the tape take-up reel 7 rotates in the direction of arrow A. The polishing tape 1 is brought into contact with a magnetic head 5, which is an object to be polished, at a predetermined wrap angle by a pass roll 8 on the traveling path, and the tape sliding surface of the magnetic head 5 is polished. As shown in FIG. 2, the polishing tape 1 has a polishing support layer 2 coated on a flexible support 2 made of polyethylene terephthalate (PET), polyethylene-2,6-naphthalate or the like. It will be. Polishing is performed by slidingly contacting the polishing layer 3 with the magnetic head 5.

The polishing layer 3 has a round-shaped first surface having a curved surface with an average particle diameter of 4 to 8 μm and a Mohs hardness of 8 or more.
And the second abrasive 4A having an angular shape having a surface having two or more flat surfaces with an average particle size of 6 to 9 μm and a Mohs hardness of 8 or more are kneaded together with a binder and the like and applied. There is.

The binder is preferably one having high dispersibility in order to satisfactorily disperse the particles of the two types of abrasives 4A and 4B and bond them to the polishing layer 3. In addition to the above-mentioned abrasives 4A and 4B and the binder, the polishing layer 3 maintains sufficient lubricity with the magnetic head 5 even when the polishing tape 1 is in a state like that, and has good running stability. So that you can keep
It is desirable to include additives such as lubricants.

The preferred thicknesses of the polishing layer 3 and the flexible support 2 vary depending on the polishing shape of the magnetic head 5, but the polishing tape 1 is for rough polishing the magnetic head 5 for the S-VHS system. In this case, if the thickness of the flexible support 2 is 30 μm, the thickness of the polishing layer 3 is 12 μm. If the thickness of the flexible support 2 is 23 μm, the thickness of the polishing layer 3 is 30 μm. The thickness is preferably about 16 μm. If the thickness of the polishing layer 3 is too large, the contact between the magnetic head 5 and the polishing tape 1 deteriorates. Therefore, it is preferable that the thickness of the polishing layer 3 is always 50 μm or less.

The polishing tape 1 of the present invention is particularly suitable for polishing the high performance magnetic head 5 as described above.
As shown in FIG. 4 and FIG. 4, it may be used for polishing the hard disk 15. When the hard disk 15 is polished, the hard disk 15 is sandwiched by two rubber rollers 18, and the polishing layers 3 of the two polishing tapes 1 are pressed against both surfaces of the hard disk 15 by these rubber rollers 18, and in this state, the hard disk 15 is indicated by the arrow B. Both sides of the hard disk 15 can be polished at the same time by rotating in the direction. In this case, a strong pressing force is applied to the object to be polished (hard disk 15) as compared with the case of polishing the magnetic head 5 shown in FIGS. 1 and 2, but the polishing tape 1 of the present invention has the above-mentioned two types. Since it has the abrasives 4A, 4B and the binder capable of improving the polishing surface property, there is no fear of deep scratches on the surface to be polished.

(Effect of the Invention) According to the present invention as described above, the average particle size is 4 to 8 μm.
The particle size and shape of the first abrasive composed of particles having a curved surface with m and the second abrasive composed of particles having an average particle diameter of 6 to 9 μm and having an angular surface were specified. While using two types of abrasives in a specific compounding ratio,
Further, a polishing layer containing a binder containing at least one of a specific vinyl chloride resin, a polyurethane resin and a polyester resin and containing polyisocyanate as a curing agent component in an amount of 10 to 50% by weight based on the amount of the abrasive. By having the above, it is possible to obtain a polishing tape which has a high polishing ability and does not cause deep scratches on the surface to be polished, which is particularly suitable for rough polishing.

The effects of the present invention will be further clarified by the following examples and comparative examples.

<Example 1> On a flexible support made of polyethylene terephthalate (PET) having a thickness of 23 μm, a polishing layer coating solution prepared by dispersing the following composition by a ball mill was applied to a thickness of 14 μm and dried. Then, a polishing layer was formed. After that, it was wound up and slit into a 1/2 inch width to prepare a polishing tape. In the following description, all “parts” mean “parts by weight”.

[Coating liquid composition] First abrasive …… 75 parts (Al ₂ O ₃ particles, average particle size 7.3 μm, Mohs hardness 9.0, “CAH-3020” manufactured by Sumitomo Chemical Co., Ltd.) Second abrasive …… 675 parts (Al ₂ O ₃ particles, average particle size 8.1 μm, Mohs hardness 9.0, “WA # 2000” manufactured by Fujimi Abrasives Co., Ltd.) Binder (vinyl chloride resin) …… 55.3 parts (87 parts vinyl chloride) %, Particle average molecular weight 2.6 × 10 ⁴ , epoxy group content 3.5% by weight, potassium sulfonate group content
0.5% by weight, said weight% is the weight% with respect to the vinyl chloride resin weight. ) Binder (sulphonic acid group-containing polyurethane resin ... 32.7 parts (molecular weight 25000 ... Molecular weight per SO ₃ Na is 25000) Binder (polyisocyanate) ...... 60 parts (3 mol of 2,4-tolylene diisocyanate) 75 wt% ethyl acetate solution of the reaction product of the compound and 1 mol of trimethylolpropane) Solvent (methyl ethyl ketone) ...... 100 parts Solvent (cyclohexane) ...... 100 parts <Example 2> The particle size of the first abrasive In a modified example, the first abrasive “CAH-3020” of Example 1 was used to obtain a Mohs hardness of 9.0, an average particle size of 4.0 μm, and an Al of “CAH-3000” manufactured by Sumitomo Chemical Co., Ltd.
An abrasive tape was prepared under the same conditions as in Example 1, except that the first abrasive was used instead of the ₂ O ₃ particles.

<Example 3> In an example in which the binder resin was changed, the vinyl chloride resin and the sulfonic acid group-containing polyurethane resin of Example 1 were replaced by ethylene glycol / neopentyl glycol / adipic acid phthalate = 0.6 / 0.5 / 1.0. Saturated thermoplastic polyester resin with a /0.2 molar ratio (“Byron 10 manufactured by Toyobo Co., Ltd.
3 ”), and other conditions were all the same as in Example 1 to prepare a polishing tape.

<Comparative Example 1> In a comparative example in which the particle diameters of the first and second abrasives are small, the first abrasive "CAH-3020" of Example 1 was used with a Mohs hardness of 9.
0, average particle size 4.0 μm, Sumitomo Chemical Co., Ltd. “CAH-3
000 "Al ₂ O ₃ particles as the first abrasive, and the second abrasive" WA # 2000 "with a Mohs hardness of 9.0 and an average particle diameter of 3.0μ.
m, "WA # 4000" manufactured by Fujimi Abrasives Co., Ltd. Al ₂ O ₃
Example 1 except that the second abrasive was used instead of the particles.
A polishing tape was prepared under the same conditions as above.

Comparative Example 2 In a comparative example using only the second abrasive, the addition amount of the first abrasive “CAH-3020” of Example 1 was set to 0 part, and the second abrasive “WA # 2000” was added. Example 1 except that the amount was increased
A polishing tape was prepared under the same conditions as above.

Comparative Example 3 In a comparative example using only the first abrasive, the addition amount of the second abrasive “WA # 2000” of Example 1 was set to 0 part, and the first abrasive “CAH-3020” was added. Example 1 except that the amount was increased
A polishing tape was prepared under the same conditions as above.

Comparative Example 4 In a comparative example using only the first abrasive, the addition amount of the second abrasive “WA # 4000” in Comparative Example 1 was set to 0 part, and the first abrasive “CAH-3000” was added. Example 1 except that the amount was increased
A polishing tape was prepared under the same conditions as above.

<Comparative Example 5> In a comparative example using only the second polishing agent, the addition amount of the first polishing agent "CAH-3000" of Comparative Example 1 was set to 0 part, and the first polishing agent "WA # 4000" was used. A polishing tape was prepared under the same conditions as in Comparative Example 1 except that the amount was increased by that amount.

<Comparative Example 6> In a comparative example in which the amount of the first abrasive contained in the abrasive was small,
Add 75 parts of the first abrasive "CAH-3020" of Example 1 to 2 parts.
The polishing tape was prepared under the same conditions as in Example 1 except that the content was changed to 0.9 parts.

<Example 4> In an example in which the first abrasive was mixed in a large amount in the abrasive, the addition amount of the first abrasive "CAH-3020" in Example 1 was changed to 75 parts.
The polishing tape was prepared under the same conditions as in Example 1 except that the number was changed to 9.2 parts.

<Comparative Example 7> In an example in which the first abrasive was mixed in a large amount in the abrasive, 75 parts of the first abrasive "CAH-3020" in Example 1 was added to 450 parts.
The polishing tape was prepared under the same conditions as in Example 1 except for the parts.

Comparative Example 8 In a comparative example in which the binder resin was changed, the vinyl chloride resin of Example 1 was replaced with a vinyl chloride-vinyl acetate copolymer (copolymerization ratio 87:13, degree of polymerization 350), The sulfonic acid group-containing polyurethane resin was replaced with polyester polyol (a reaction product of 1 mol of adipic acid, 1 mol of diethylene glycol and 0.06 mol of trimethylolpropane), and the other conditions were the same as in Example 1 to prepare a polishing tape. .

<Example 5> In the example in which the material of the second abrasive was changed, the second abrasive "WA # 2000" of Example 1 was used, and the Mohs hardness was 9.5, the average particle size was 8.0 µm, and the Fujimi abrasive industry was used. A polishing tape was prepared under the same conditions as in Example 1 except for the square-shaped particles of SiC abrasive "GC # 2000" manufactured by Co., Ltd.

<Comparative Example 9> Comparative Example 9 in which the amount of the binder with respect to the polishing agent was small,
The amount of the vinyl chloride resin 55.3 parts to 15.0 parts, the sulfonic acid group-containing polyurethane resin 32.7 parts to 9.2 parts, and the polyisocyanate 60 parts to 16.9 parts were changed, and all other conditions were the same as in Example 1. An abrasive tape was created.

<Comparative Example 10> In a comparative example in which the amount of the binder with respect to the abrasive was large, 55.3 parts of the vinyl chloride resin of Example 1 was added to 17.6 parts, 32.7 parts of the sulfonic acid group-containing polyurethane resin was added to 9.2 parts, and 60 parts of polyisocyanate was added. The polishing tape was prepared under the same conditions as in Example 1 except that the amount was changed to 16.9 parts.

Table 1 shows the composition of the polishing layers of the polishing tapes prepared in Examples 1 to 5 and Comparative Examples 1 to 10 as described above.

The rough polishing tapes prepared in the above-mentioned Examples and Comparative Examples were respectively loaded into a polishing device, the ferrite video head (magnetic head) was roughly polished, and the polishing amount of the magnetic head was measured. The rough polishing amount of the magnetic head was determined under the same polishing conditions in all the polishing tape tests, and was determined from the difference (μm) in height between the magnetic heads before and after polishing. Then, in order to examine the depth of scratches on the surface of the magnetic head due to the rough polishing, the finish polishing was performed with the finish polishing tape disclosed in Example 1 of JP-A-60-232503 for 20 seconds. The state of deep scratches remaining in the rough polishing that could not be removed with was examined. The depth of the deep scratches is the number of scratches having a width of 0.5 μm or more, which is confirmed by observing the surface of the magnetic head with a microscope.

Table 2 shows the measurement results of the polishing amount of the magnetic head by the rough polishing and the number of deep scratches of the rough polishing remaining on the surface of the magnetic head after the final polishing.

From Table 2, it is found that the polishing tapes of Examples 1 to 5 have a large polishing amount of the magnetic head and do not leave deep scratches on the surface of the polished magnetic head, and thus are suitable as a rough polishing tape. . That is, the polishing tape of the present invention is the first
Second abrasive because it contains both the first abrasive and the second abrasive in appropriate amounts.
It was found that it has both a large polishing ability with the first abrasive and an ability to prevent deep scratches with the first abrasive.

First, in comparison with Comparative Examples 3 and 4 not containing the second abrasive, in Examples 1 to 4, the Al ₂ O ₃ abrasive having a square shape with an average particle size of 8.1 μm and a Mohs hardness of 9.0 was used as the second abrasive. Since it is contained as an abrasive, a large polishing amount of the magnetic head can be obtained. Further, in comparison with Comparative Example 2 containing no first abrasive, Examples 1 to 5 contained a round Al ₂ O ₃ abrasive having an average particle size of 4.0 to 7.3 μm and a Mohs hardness of 9.0, and thus magnetic It can be seen that no deep scratches are left on the head surface.

In addition, in the comparison between Examples 1 and 4 and Comparative Examples 6 and 7, the compounding amount of the round-shaped first abrasive with respect to the total polishing amount is large in Comparative Example 6 where the compounding amount is small and the compounding amount is large. Comparative Example 7
Shows that the amount of polishing is reduced, and that the range of this compounding amount is 5 to 30% is an appropriate range that does not leave deep scratches on the magnetic head surface.

Further, in comparison with Comparative Example 8 in which the binder has a different composition, it can be seen that the one according to the above example does not leave deep scratches on the surface of the magnetic head. This binder is used in embodiment is favorably dispersed Al ₂ O ₃ abrasives, presumably because less likely to generate the aggregation of deep scratches cause attaching a Al ₂ O ₃ abrasive.

Regarding the material of the polishing agent, a comparison between Example 1 and Example 5 shows that even if a SiC polishing agent is used as the second polishing agent, the particles having an average particle size of 8.0 μm and a square shape with a Mohs hardness of 9.5 are used. Therefore, the polishing amount of the magnetic head is large, and there is no great change due to the abrasive type. Further, in comparison with Comparative Examples 1 and 5, the round-shaped Al ₂ O ₃ abrasive was the first abrasive.
It can be seen that the presence of deep scratches on the surface of the magnetic head is remarkably improved by being mixed as the polishing agent.

In the comparison between Example 1 and Comparative Examples 9 and 10, the total amount of binder /
Weight percent of total abrasive When the content is less than 10% and 5% (Comparative Example 9), the amount of the binder is insufficient, the abrasive particles are likely to fall off from the polishing layer, and the polished video head surface is deeply scratched. It is believed that Also, in the case of more than 50% and 55% (Comparative Example 10), it is considered that the polishing amount of the magnetic head is small because the abrasive particles are buried in the binder and the polishing ability is not fully exhibited. To be

According to the rough polishing tape of the above embodiment, since no deep scratch is left on the surface of the magnetic head, the amount of finish polishing tape used for finish polishing and the finish polishing time can be greatly reduced. Further, such a rough polishing tape does not leave deep scratches, and also exerts an action of preventing the abrasive particles that have been shattered from being embedded in the surface to be polished.

Further, the magnetic conversion characteristics of the magnetic head that was completed by rough polishing the magnetic head with the rough polishing tape of the above example and then finish polishing were superior to the electromagnetic conversion characteristics of the magnetic head that was rough polished and finish polished in the comparative example. It turns out that there is also an advantage. It is considered that this is because it is difficult to form a work-affected layer near the surface of the magnetic head that greatly affects the electromagnetic conversion characteristics.

The polishing tape of Comparative Example 1 had the same composition as that of Example 1 except that the particle size of the second abrasive was small, and the polishing amount was smaller than that of the example, but no scratches were generated. It can be used as a polishing tape for finish polishing.

The present invention can be variously modified without departing from the scope of the invention and is not limited to the above embodiments. Further, the polishing tape according to the present invention is not limited to the elongated tape shape shown in the examples, but includes a disk shape in which a polishing layer is formed on a thin circular support.

[Brief description of drawings]

FIG. 1 is a schematic view of a polishing apparatus using the polishing tape of the present invention, FIG. 2 is an enlarged view of the polishing tape and a magnetic head, FIG. 3 is a schematic perspective view of another polishing apparatus, and FIG. It is sectional drawing. 1 ... Abrasive tape, 2 ... Flexible support, 3 ... Abrasive layer 4A ... First abrasive, 4B ... Second abrasive, 5 ... Magnetic head

Claims (1)

(57) [Claims] 1. A polishing tape comprising a flexible support and a polishing layer mainly comprising an abrasive and a binder, wherein the abrasive has an average particle size of 4 to 8 μm and a Mohs hardness of 8 or more. The first abrasive having a curved surface, and the second abrasive having an angular shape having an average particle size of 6 to 9 μm, a Mohs hardness of 8 or more, and two or more flat surfaces on the surface thereof. With respect to the total amount of the abrasive and the second abrasive,
The first abrasive is contained in an amount of 5 to 30% by weight, and as the binder, an epoxy group- and sulfonic acid group-containing vinyl chloride resin, a sulfonic acid group-containing polyurethane resin, and ethylene glycol, neopentyl glycol, phthalic acid, adipine It contains at least one of saturated thermoplastic polyester resin containing acid as a main component, and contains polyisocyanate as a curing agent component, and the amount of the binder is the sum of the first abrasive and the second abrasive. A polishing tape characterized by being 10 to 50% by weight based on the amount.