JPH0343155A - Abrasive tape and its manufacture - Google Patents

Abstract

PURPOSE:To prevent loosening of the roll of an abrasive tape, when winding the abrasive tape into a roll and curing the roll, and prevent differences in the grinding or polishing property of the abrasive tape between the ends of the tape by using saturated thermoplastic branched polyester resin as a binder. CONSTITUTION:An abrasive material is mixed with a binder solution and stirred, and, after the mixture slurry solution is filtrated by a filter, it is uniformly applied on an elastic supporter tape and the tape applied with the solution is dried by a drier as the solution is evaporated and dissipated, and the tape is then wound into a roll by a winder, whereby a desired abrasive tape is obtained. In this case, a mixed binder containing saturated thermoplastic branched polyester is used as at least one part of the binder. Thus, when the abrasive tape is cured as it is wound into a roll, loosening of the roll does not occur, and, even when the tape is used for finish polishing of a magnetic disk, it would not cause galling of the finish surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polishing tape used for polishing the surfaces of magnetic disks, magnetic heads, etc.

[Conventional technology]

Computer hard disks are made by plating nickel, phosphorus, etc. on an aluminum alloy base, and then sputtering or plating iron, chromium, cobalt, etc. on this surface. At that time, in order to fix the sputtered or plated metal and improve its magnetic properties, the surface coated with nickel, phosphorus, etc. is polished, leaving only fine scratches (
It is necessary to add texture. A polishing tape is used for this polishing process. Further, for video or audio magnetic heads, the surface on which the magnetic tape slides must be particularly smooth, and abrasive tape is also used to finish this surface.

Such abrasive tapes are made by mixing abrasive mtJi liquid, which is prepared by kneading fine abrasives (abrasive grains), a binder, and various additives used as necessary, in a solvent, to give it flexibility. It is coated on a support tape with a
It has been passed. The polishing method for this abrasive tape is, for example, as described in Japanese Patent Publication No. 53-68490. 2. Applying the tIl solution onto a visible support and drying it to form an abrasive layer on the support tape, and winding it up to form a roll-like product.Coating, drying and winding. The process consists of 3. A curing process in which the rolled product is treated at a predetermined temperature and humidity for a certain period of time; 4) A commercialization process in which the rolled product is cut into a predetermined width and length according to the customer's request. . In the manufacturing process of abrasive tape, the product is wound into a roll as described above and the rolled product is cured at a predetermined temperature and humidity because it is more efficient to do so.

[Problem to be solved by the invention]

However, when curing the abrasive tape in a roll form, thermal deformation occurs in the abrasive tape, causing the inside (start of winding) and outside (
At the end of the roll), there is a problem that differences tend to occur in grindability and polishability. (This phenomenon is hereinafter referred to as "winding tightening" - "winding loosening.") This phenomenon occurs even if the product is wound into a roll and curing is performed in the roll, even if the curing is performed under mild conditions, and regardless of the brand of the product. This is a phenomenon that is observed to a greater or lesser extent regardless of the situation.

The second problem to be solved by the present invention is that conventional polishing tapes manufactured using linear polyester resin as a binder cause scratches on the surface of the object to be polished.

In recent years, there has been a strong demand for compact magnetic disks with higher recording density, smaller size, and higher performance.
From the perspective of R conversion characteristics, it is necessary to reduce noise and increase output, while from the perspective of error characteristics, it is necessary to reduce defects caused by such scratches. Is this due to the polishing tape of the nickel-phosphorus interlayer? i71! There is an increasing demand for abrasive tapes that produce uniform, fine textures in the finish, but not scratches.

In particular, in magnetic heads, such as magnetic heads for video, the recording wavelength has become even shorter due to the increase in the capacity of video tapes, and as a result, the performance required of the magnetic heads has become even higher.

As a result, finishing using conventional abrasive tapes is no longer able to meet these demands in terms of quality, so it is necessary to provide abrasive tapes that not only provide highly smooth finished surfaces but also do not cause cracks, scratches, or chipping of magnetic heads. Demanded by the industry.

Therefore, the present invention provides an abrasive tape that winds an abrasive tape into a roll, and when curing the roll, the winding is tightened so that no looseness occurs during each roll, and there is no difference in grinding and abrasive properties between the beginning and the end of the roll. The purpose is to provide a manufacturing method thereof.

Another object of the present invention is to provide a polishing tape that does not cause scratches on the final polished surface of an object to be polished, such as a magnetic disk or a magnetic head, and a method for manufacturing the same.

[! lI! Means for Solving III] In order to solve the above-mentioned problems, the present inventors conducted intensive studies on the components used in the production of the 01 abrasive sheet, especially the binder, and found that polyester was used as a binder for the abrasive tape. When using resin, if branch polyester resin is used instead of linear polyester resin, when curing the abrasive tape in roll form, the winding will be tight and no loosening will occur, making it suitable for 1iJ111ff finishes such as magnetic disks and magnetic heads. It was discovered that it is possible to produce an abrasive tape that does not cause scratches on its finished surface even when used, and the present invention was developed. This invention was made as follows.

Conventionally, many proposals have been made to use thermoplastic resins, thermosetting resins, reactive resins, and mixtures thereof as binders for abrasive sheets (for example, Japanese Patent Laid-Open No. 1983-1999)
No. 129927, No. 62-94267, No. 62-9426
No. 9, No. 62-176771, No. 62-199364,
62-203767, 62-203768, 63-
No. 16979, No. 63-84879, formerly published in 1972
-97408, pages 2 and 3).

However, as a binder, (1) it must be dissolved in an organic solvent when preparing a coating solution, and (2) when it is manufactured into an abrasive tape, the binder must not soften or melt before being thermally decomposed. required.

Therefore, in the production of abrasive sheets, a thermoplastic resin that is easily soluble in solvents is used as a binder, a chain extender and/or a crosslinking agent is added to it, and a wave cloth is dried on a visible support tape, followed by a curing treatment. It has become common practice to convert the binder layer into a heat-resistant thermosetting resin by doing this. In such manufacturing processes, biaxially oriented polyethylene terephthalate films are used industrially as corrugated flexible supports.

Therefore, as a binder, saturated thermoplastic polyester resin, which has high adhesion with this film, is widely used in the manufacture of abrasive sheets (for example,
-68490), this saturated thermoplastic polyester resin (hereinafter abbreviated as polyester resin) is a co-polyester resin whose acid component is a dicarboxylic acid mixture and whose glycol component is alkylene glycol, polyalkylene glycol, or a mixture thereof. There is a glycol component,
It is possible to change the structural composition of the polymer, such as the dicarboxylic acid component, copolymerization ratio, molecular weight, and blocking properties.

Therefore, after researching a polishing sheet binder that can achieve the above purpose, the present inventors found that polishing sheet-1
When polyester resin is used as a binder for magnetic disks and It has been found that it is possible to produce an abrasive tape that does not cause scratches on the finished surface even when used for abrasive finishing.

The branch polyester resin referred to herein is a polyester resin whose glycol component is alkylene glycol, polyalkylene glycol, or a mixture thereof as the acid component of a dicarbonate mixture, and has an ester-forming functional group of 31I!
A copolymerized polyester resin having branched molecules in the polymer molecular chain by copolymerizing the above-mentioned compounds,
It may be either a random copolymer or a block copolyester, or a mixture thereof, or a mixture with an X-ray polyester copolyester, ff1, or 6.

It should be noted that there has already been a proposal to use branch polyester resin as an adhesive agent (Special Public Interest Publication in 1973).
37974 and Japanese Patent Publication No. 48-37975), these proposals are all related to adhesives and not to binders for abrasive tapes.

The dicarboxylic acids used in the production of the branched polyester used in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and phthalic acid, and carbon atoms such as adipic acid, superric acid, azelaic acid, and sebacic acid. Examples include 2 to 12 aliphatic dicarboxylic acids and ester-forming 18 conductors of these acids. Examples of alkylene glycols include those with 2 to 10 carbon atoms, such as ethylene glycol, propylene glycol, 1,4-butanediol, and neopentyl glycol.
Oxycaproic acid, β-hydroxyethoxyamne, 0.
? ! Examples include hydroxycarboxylic acids such as F acid and esters thereof, and further examples of polyalkylene glycols include diethylene glycol, triethylene glycol, polyethylene glycol, and bolide 1-ramethylene glycol.

Examples of compounds having three or more ester-forming functional groups for introducing branching into the polyester molecular chain include tricarballylic acid, trimesic acid, trimellitic acid and ester-forming derivatives of these acids, and compounds having three or more hydroxyl groups. Examples include polyols such as trimethylolpropane, pentaerythritol, glycerin, sorbitol, and the like.

Although the polyester made of these components can be produced in any manner, a conventional polyester production method such as a direct esterification method or a transesterification method can be employed.

To block copolymerize two different polyesters (e.g., a polyester for hard segments and a polyester for soft segments), both polyesters can be mixed briefly in the molten state, or polymers with 11 Any method can be used, such as bonding both polyesters using a diisocyanate having two or more H groups, N-acylbislactam, or the like.

The chain extender and crosslinking agent used in the present invention contain two to three functional groups that can react with the hydroxyl group or carboxyl group at the end of the polyester to form a bond such as a urethane bond or an ester bond. Compounds having the following are preferred. Specific examples thereof include 1. alkylene diisocyanate and/or alkylene triisocyanate compounds such as 2.4-) lylene diisocyanate and its trimethylolpropane adduct, 2.6-tolylene diisocyanate, triphenylmethane triisocyanate,
Hexamethylene diinocyanate modified products, etc. 2. Epoxy compounds ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether.

Glycerol diglycidyl ether, glycerol triglycidyl ether, polypropylene glycol diglycidyl ether, diglycidyl ether of [bis(4-hydroxyphenyl)dimethylethane], etc.

3. Aziridine compounds, such as tris(1-aziridinylphosphine oxide), trimethylolpropane-triβ-azinylpropionate, and the like.

In practice, the polyester is used after being dissolved in a solvent. Examples of the solvent include γ setone, methyl ethyl getone, cyclohexanone, toluene, xylene, ethyl acetate, and mixed solvents thereof. Other additives such as IF antistatic agents, dispersants, and coupling agents may be used in combination.

The abrasives used in the present invention include corundum, emery, garnet, aluminum oxide, α-iron oxide, silicon carbide, zirconium oxide, chromium 11 oxide, nitrogen f-arsenic, diamond, etc., and these may be one or two types. The above can be mixed and used.

The average particle diameter of the abrasive is usually 0.3 to 40 microns, preferably 0.5 to 30 microns.

Mixing these abrasives with the polyester resin solution,
Knead using a roll mill or the like to obtain a uniform polishing slurry solution. This polishing slurry solution is filtered using a membrane filter or the like in a filtration device. The chain extender and crosslinking agent described above are added to the polishing slurry solution before or after this filtration. The filtered abrasive slurry solution is stored in a reservoir with an agitator to avoid settling of the abrasive particles.

The slurry solution stored in the reservoir is uniformly applied onto a flexible support tape, and the applied tape is dried by continuously evaporating the solvent using a dryer, and then wound into a roll using a winder. take.

Soto When the present invention is carried out, the abrasive tape is wound into a roll,
When curing the roll, there is no tightening or loosening of the roll, and there is almost no difference in grinding and polishing properties between the beginning and the end of the roll.

In addition, even when polishing magnetic disks, magnetic heads, etc. with the manufactured polishing tape, no scratches will be caused on the final polished surface of the polished object. [Example] Grindability,
The difference in polishability is extremely small. Therefore, a new evaluation method was developed and tested as described below. gJJ
As a result of testing various objects to be polished, it was found that pencil lead was a suitable material for the purpose of this test and gave reliable and reproducible results. Therefore, I created a jig that would allow me to hold a pencil lead vertically and apply any load to it.

This jig was placed on the polishing tape set on the XY turntable, and the core was polished under the specified conditions (travel speed and travel distance) by applying a constant load.Then, the length of the core after polishing decreased. was measured down to the micron level using a microscope.The measurement was repeated five times, and the average value was determined to be the polishing amount.

In order to quantitatively display the tightness and winding condition of a roll, it is necessary to take the amount of polishing at the beginning of the roll (window side of the roll) as the basis and compare it with the amount of polishing at the middle and end of the roll (outside the roll). The ratio was determined and expressed as a percentage.

Evaluation of the use of the experimental abrasive tape for polishing magnetic disks, magnetic heads, etc. was performed using a nickel-phosphorus substrate (small piece) under the same conditions (rotation speed, tape feed speed,
Polishing time, type of polishing liquid and its flow rate, etc.
After washing the polished disk with a predetermined liquid, the surface of the disk was observed (for unevenness in polishing, presence of scratches, roughness, etc.).

Specific examples of the invention will be described below. However, these are examples of the present invention and do not limit the present invention in any way.

- 1 to 7 parts of aluminum oxide (average particle size 3 microns) were dried in a dryer at 120°C for 1 hour.

A polyester resin as shown in the following table was added to a mixed solvent of toluene, methyl ethyl getone, and ethyl M acid (5: 4: 2 weight ratio), and the aluminum oxide was mixed therewith and stirred well. . After adding chain extenders and crosslinking agents as shown in the table, the coating liquid is filtered using a cartridge filter with a size of 1 micron (nominal). I! I got 1 kick.

This coating liquid was applied uniformly to a thickness of 40 microns on a biaxially oriented polyethylene terephthalate film with a thickness of 25 microns, and then passed through a first stage dryer maintained at 90°C.
The solvent was evaporated in a second stage dryer maintained at 20° C., and after drying, the material was wound around a paper core with an outer diameter of 95 rings, and the length of all six windings was 1000 nt throughout this test.

This wound roll-shaped polishing tape was cured for 24 hours at a temperature of 60° C. and a humidity of 60% in a separate drying room. After I&, it was slit into 50 mm 1 liter pieces using a slitter, and wound up into a product core with an outer diameter of 3111 wheels.

The temperature and humidity shown here are just examples, and the temperature during treatment is preferably 40 to 1800, and the humidity is preferably 50% or more.

Grindability and abrasiveness tests were conducted using products wound on a core with a diameter of 55 (the end of the roll), a diameter of 75 (the middle of the roll), and a diameter of 100 (the beginning of the roll). The abrasive tape wrapped around the area) was collected and used as a sample for testing.

In addition, in the following table, polyester resin (A) is a linear copolymerized polyester, (B) is a block copolymerized branched polyester of hard segments and soft segments, and (C) is a random copolymerized branched polyester, all of which are commercially available or commercially available. We obtained a product that was sold and provided as a trial product and used it for testing. Furthermore, an isocyanate-based curing agent was used as a chain extender and crosslinking agent.

As is clear from the above detailed description and the table above, the abrasive tape produced by the method of the present invention is neither tightly wound nor loosened, and the difference in grindability between the beginning and end of the roll is extremely small.

Furthermore, as can be seen from the comparison with the comparative example, the surface quality of the surface polished by the polishing tape using the branched polyester resin as the binder was significantly improved compared to the surface polished using the conventional linear polyester resin as the binder. It turns out that

Claims (1)

[Claims] 1. An abrasive tape in which an abrasive layer is formed by applying an abrasive coating liquid containing an abrasive material and a binder onto a flexible support tape, wherein the binder is a saturated thermoplastic branched polyester. An abrasive tape characterized by the use of resin. 2. Mix and stir the abrasive material with the binder solution, then filter this mixture slurry solution through a filter, apply it uniformly onto a flexible support tape, and then put the coated tape in a dryer to evaporate the solvent. 1. A method for manufacturing an abrasive tape, which comprises scattering, drying, and winding up into a roll using a winder, wherein a mixed binder containing at least a portion of a saturated thermoplastic branched polyester is used as the binder. 3. The manufacturing method according to claim 2, wherein a chain extender and/or a crosslinking agent is added before or after filtering the mixture slurry solution through a filter, and then the mixture slurry solution is coated on a flexible support tape. 1. A method for producing an abrasive tape, which comprises uniformly coating the tape, drying it, winding it up into a roll, and curing the roll. 4. The manufacturing method according to claim 3, wherein the chain extender and crosslinking agent are difunctional and/or trifunctional isocyanate compounds. 5. The manufacturing method according to claim 3, wherein the chain extender and crosslinking agent are difunctional and trifunctional aziridyl compounds. 6. The manufacturing method according to claim 3, wherein the chain extender and crosslinking agent are difunctional and/or trifunctional epoxy compounds. 7. The manufacturing method according to claim 3, wherein the roll is treated in a temperature environment of 40 to 180°C for a predetermined period of time. 8. The manufacturing method according to claim 3, wherein after coating, drying and winding up the slurry solution, the support tape on which the polishing layer is formed is placed in an atmosphere with a humidity of 50% or more.