JPH0616989B2 - Polishing tape - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polishing tape used for polishing a magnetic head of a magnetic recording / reproducing apparatus, and more particularly to an improvement of a binder used in a polishing coating solution for the polishing tape. Is.

(Prior Art) A magnetic head for video or high-grade audio is required to have a smooth tape sliding surface. Therefore, when manufacturing a magnetic head, the magnetic head is generally placed at a predetermined position after rough cutting. Then, an abrasive tape is run between two reels sandwiching this magnetic head to finish the tape sliding surface of the magnetic head smooth. Such an abrasive tape is generally prepared by kneading a fine abrasive (particles), a binder (binder), and an additive such as a lubricant, which is added as necessary, on a flexible support to prepare an abrasive coating liquid. Since the support has flexibility, the support can be adapted to the curved shape of the tape sliding surface of the magnetic head to precisely polish this surface.

Conventionally, such a tape is, for example, zinc oxide (Z
(nO) abrasive, a binder mainly composed of vinyl chloride resin, and various additives such as a curing agent such as polyisocyanate and a lubricant such as silicone oil are kneaded, and a polishing coating solution is kneaded on the support. There is known a cleaning tape formed by applying the coating to the. Therefore, it is conceivable, for example, to use only the abrasive in the cleaning tape as harder than zinc oxide and use it as the abrasive tape.

(Problems to be solved by the invention) However, in the polishing tape using the vinyl chloride resin as the binder as described above, the dispersibility of the abrasive by the vinyl chloride resin is poor, and the abrasive becomes a solid. Sometimes it was concentrated in one place, which was a cause of scratching the surface to be polished.

Recently, a head made of permalloy has been widely used, but since the permalloy is an alloy which is soft and easily corroded, the tape sliding surface of the head has a property of being easily corroded. The above-mentioned polishing tape using a vinyl chloride resin as the binder is easily desalted from the binder, and this dehydrochlorination easily corrodes the surface to be polished in contact with the tape. Therefore, when the object to be polished is a material that is likely to be corroded like the permalloy head, it is particularly susceptible to this effect, which is not preferable.

In addition, the commonly used materials have a high surface electrical resistance due to their electrical insulating properties, and are liable to be charged with static electricity due to friction, etc. As a result, dust and the like tend to adhere to the surface of the polishing tape.
The attached dust scratches the polished surface of the magnetic head. In addition, there are problems that the winding shape of the polishing tape is disturbed by the electrification and the stability of tape running is deteriorated.

In view of the above circumstances, the object of the present invention is excellent in dispersibility of the abrasive material, less likely to be corroded even on the surface to be corroded such as permalloy head, which further reduces electrostatic charging due to friction. It is an object of the present invention to provide a polishing tape that is particularly suitable for finish polishing.

(Means for Solving Problems) The polishing tape of the present invention is a polishing tape in which a support is coated with a polishing coating solution prepared by dispersing an abrasive in a binder and dried to form a polishing layer. Wherein the binder is one or more vinyl compounds selected from a compound having a dialkylaminoalkyl group and a vinyl compound having a quaternary salt of a dialkylaminoalkyl group, and a vinyl group-containing monomer copolymerizable with the vinyl compound. It is characterized by comprising a copolymer consisting of

By using the above copolymer as a binder, a high affinity between the abrasive powder and the binder can be obtained.

By mixing and using the above-mentioned copolymer, a vinyl chloride-based copolymer and a urethane resin which have been conventionally used, the dispersibility of the abrasive powder is increased, and the abrasive layer coated on the support becomes uniform and smooth. Property and sliding runnability can be improved.

The vinyl compound having a dialkylaminoalkyl group used in the present invention has the following general formula (A), and the vinyl compound having a quaternary salt of the dialkylaminoalkyl group has the following general formula (B) or the following general formula (C). Indicated by.

And a vinyl compound (Y) copolymerizable with these vinyl compounds, if necessary, and represented by the following general formula.

In the above general formula, each component of the compound is described for convenience so as to be regularly arrayed, but each component is regularly repeated at a constant ratio except in the case of the above general formula. It may be arranged randomly.

Two or more kinds of the vinyl compound unit having a dialkylaminoalkyl group, the vinyl compound unit having a dialkylaminoalkyl quaternary salt and Y may be present.

The vinyl compound having a dialkylamino group is preferably one bound to the main chain with -CO ₂ -and -CONH-, and particularly preferred ones are Is.

Preferred examples of the dialkylamino quaternary salt include And so on.

The copolymerized vinyl monomer represented by Y in the structural formula is vinyl acetate, vinyl alcohol, maleic acid, maleic anhydride, acrylic acid, acrylic acid esters, methacrylic acid, methacrylic acid esters, acrylic acid having a glycidyl group. Alternatively, it is a monomer having at least one copolymerizable vinyl group selected from esters of methacrylic acid, acrylonitrile, vinyl chloride, vinylidene chloride, vinyl propionate and the like.

0.5 to 50 wt% of vinyl compound having dialkylaminoalkyl group or quaternary salt of dialkylaminoalkyl group
%, More preferably 1 to 40 wt%, most preferably 2 to 30 wt%.

The component represented by the general formula Y of the copolymerization component may be a copolymer of two or more of the above compounds for the purpose of improving solubility, film physical properties, adhesion to a support and the like. As molecular weight 10,000-50,0
00 is preferable, and more preferably 15,000 to 30,000.

The vinyl-based copolymer is contained in the polishing layer in an amount of preferably 5 to 90 wt%, more preferably 20 to 80 wt%, based on the total amount of the binder.

The above compounds may be used as a mixture with other binders.
As such a binder, those conventionally used as a binder for polishing tapes can be used, including vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride- Vinyl acetate-maleic acid copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacrylic acid ester-chloride Vinylidene copolymer, methacrylic acid ester-
Styrene copolymer, thermoplastic polyurethane resin, phenoxy resin, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, polyvinyl butyral, cellulose derivative, styrene -Butadiene copolymer, polyester resin, phenol resin, epoxy resin, thermosetting polyurethane resin, urea resin, melamine resin, alkyd resin, urea-formaldehyde resin, or a mixture thereof may be used. Furthermore, when used in combination with a polyester or polyurethane resin, scratches on the surface to be polished are prevented, polishing properties are dramatically improved, and excellent performance as a polishing tape can be exhibited. Further, as a crosslinking agent, 3
If a functional isocyanate compound such as a reaction product of 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate is used in combination, durability and the like can be further improved.

(Example) Hereinafter, the Example of this invention is described in detail. The polishing tape according to the embodiment of the present invention includes a support 1 having flexibility and a polishing layer 2 formed on the support 1 as shown in the drawings.

The polishing layer 2 is manufactured by coating the support 1 with a polishing coating liquid obtained by kneading the polishing material 3, a binder, and various additives used as necessary, and drying the coating liquid.

When polishing the tape sliding surface of the magnetic head 4 which is an example of an object to be polished, the polishing tape is transferred from one reel (not shown) arranged at two positions sandwiching the magnetic head 4 to the other. The polishing layer 2 is slid on the magnetic head 4 while traveling at a constant speed. At this time, the tape sliding surface of the magnetic head 4 is smoothly polished by the hard abrasive 3 protruding from the surface of the polishing layer 2.

Further, in the present invention, a lubricant is added as an additive to the polishing coating liquid together with the above-mentioned binder as in the case of cleaning tapes that have been widely used in the past, to improve the running stability of the polishing tape. Is desirable.

The abrasive is Mohs hardness 6 which is harder than the abrasive used in conventional cleaning tapes.
The above is preferable, and the Mohs hardness of 8 or more is particularly preferable.

Examples of such high Mohs hardness include chromium oxide (Cr ₂ O ₃ , Mohs hardness 8.5), aluminum oxide (α-Al ₂ O ₃ , Mohs hardness 9), silicon carbide (β-SiC, Mohs hardness 9.5). ) And the like, but especially for finish polishing, chromium oxide is suitable since it has excellent hardness and is unlikely to damage the surface to be polished, since chromium oxide has an appropriate hardness.

It is preferable that this abrasive has a particle size of about 16 μm to 0.1 μm.
Particles having a particle size of about m to 0.1 μm are preferable.

When the object to be polished is a magnetic head, the thickness of the polishing layer 2 formed by the polishing coating liquid containing the above-mentioned abrasive, binder, additive, etc. depends on the shape and material of the magnetic head. If this thickness is too thick, the contact between the magnetic head and the polishing tape will be poor, so it is preferable that the thickness be 50 μm or less.

Examples of the flexible support 1 include polyethylene terephthalate (PET), polyethylene 2,6-
Polyesters such as naphthalate; polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate, polycarbonate,
It is also possible to use plastics such as polyimide and polyamide-imide, and plastics obtained by vapor deposition of metal such as aluminum.

The form of the polishing tape support may be a film, a tape, a sheet, or the like, and various materials are selected as necessary according to the form.

As the organic solvent used for applying the polishing coating solution, acetone,
Methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketone systems; methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, glycol acetate monoethyl ether, etc. ester systems; ethyl ether, glycol dimethyl ether, glycol monoethyl ether, dioxane, tetrahydrofuran, etc. Ether-based; aromatic hydrocarbons such as benzene, toluene and xylene; chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin and dichlorobenzene can be selected and used.

Next, more detailed description will be given with reference to specific examples.

<Example> A polishing coating solution having a thickness of 5 µm was coated with a polishing coating solution having the following composition on a polyethylene terephthalate (PET) support having a thickness of 12 µm and dried to prepare a polishing tape. In the following description, all parts are parts by weight (weight of solid content). In addition,
The polishing coating liquid having the following composition was kneaded with a ball mill for 50 hours.

Polishing liquid composition ・ Cr ₂ O ₃ (granular, size 0.3 μm, Mohs hardness 8.5)
...... 300 parts ・ Vinyl chloride resin (VAGH manufactured by UC) ・ ・ ・ 35 parts ・ Vinyl copolymer, (See Table-1,) ・ ・ ・ 20 parts ・ Soybean lecithin ・ ・ ・ 2.4 parts ・ Silicone oil (dimethyl poly) Siloxane) 0.1 part Methyl ethyl ketone 400 parts Toluene 400 parts After kneading the polishing liquid of the above composition, add 18 parts of Nippon Polyurethane Coronate L to this polishing liquid and knead for 10 minutes with a ball mill. The final coating liquid was prepared.

Samples of Examples 1 to 9 and Comparative Example were obtained as shown in Table 1, these samples were evaluated and measured by the following methods, and the results are shown in Table 2.

Driving performance evaluation: Videotape recorder Matsushita Electric Industrial N
V8310 was used to evaluate the corrosiveness of the permalloy head.

Measurement of electrostatic potential: The electrostatic potential of the tape at the outlet of the rotating cylinder when the video tape recorder was run was measured. The electrostatic potential is measured by TREK's surface electrometer MOD.
EL344 was used.

Evaluation of scratches on head surface: The ferrite video head was polished for 1 minute with each polishing tape, and then the surface to be polished was evaluated by the number of scratches having a width of 2 μm or more as confirmed by a microscope.

The head corrosion is the observation of the head surface after keeping the tape in contact with the head at 60 ° C. and 80% RH for 3 days.

From Table 2 above, it can be seen that the polishing tape of the present example has the head surface scratches remarkably reduced and the electrostatic charge due to friction on the head surface has been sufficiently prevented as compared with the comparison tape. The dialkylaminoalkyl group or the quaternary salt of the dialkylaminoalkyl group improves the dispersibility of the polishing material, and as a result, the polishing material is uniformly dispersed in the polishing layer to prevent scratches on the surface to be polished, and also to prevent static electricity due to friction. The quaternary salt of a dialkylaminoalkyl group or a dialkylaminoalkyl group prevents dehydrochlorination, and as a result, the surface to be polished is corroded by dehydrochlorination, particularly permalloy which is easily corroded. It acts to prevent corrosion of the polished surface.

(Effect of the Invention) The polishing tape of the present invention uses a binder containing a quaternary salt of a dialkylaminoalkyl group or a dialkylaminoalkyl group, and is compared with a conventional one not containing these. Further, it is possible to obtain a far superior effect of preventing head scratches, an effect of preventing head corrosion, and an effect of preventing electrostatic charge due to friction.

That is, the vinyl compound resin is uniformly present on the surface of the abrasive due to the presence of the quaternary salt of the dialkylaminoalkyl group and the dialkylaminoalkyl group, and the abrasive and the vinyl compound resin are locally present in the polishing layer. The above-mentioned effect can be obtained because the situation does not occur and there is no possibility of scratching the polished surface of the magnetic head. Also,
The head corrosion prevention effect is considered to be related to the presence of amino groups. It is considered that the main reason for the effect of preventing electrostatic charge due to friction is that the amount of electrostatic charge generated during friction is extremely small.

[Brief description of drawings]

The drawing is an enlarged cross-sectional view of a polishing tape according to an embodiment of the present invention during polishing of a magnetic head. 1 ... Flexible support, 2 ... Abrasive layer 3 ... Abrasive material, 4 ... Magnetic head

Claims (2)

[Claims] 1. A polishing tape comprising a flexible support coated with a polishing coating liquid containing an abrasive and a binder and dried to form a polishing layer, wherein the binder is a dialkylaminoalkyl group. Of one or more vinyl compounds selected from vinyl compounds having a quaternary salt of a dialkylaminoalkyl group and one or more compounds of a vinyl group-containing monomer copolymerizable with the vinyl compound A polishing tape characterized by being united. 2. The vinyl compound having the dialkylaminoalkyl group is represented by the following general formula (A), and the vinyl compound having a quaternary salt of the dialkylaminoalkyl group is the following general formula (B) or the following general formula: The polishing tape according to claim 1, which is represented by (C). General formula: