JPH11114793A - Cloth used for manufacture of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of a crash by specifying rupture strength and tensile elongation, using multifilament for warp, and filaments different in thermal shrinkage percentage for both or one of warp and weft, and forming at least one of the filaments of multifilament of specific denier formed by splitting composite fiber. SOLUTION: Cloth for wiping or polishing the substrate surface of a magnetic recording medium or the like is formed of satin, and longitudinal rupture strength by a JISL1096 A method is 20 kgf/50 mm or more, and tensile elongation is 5%/5 kgf/50 mm or less. Multifilament is used for warp, and filaments different in hot water shrinkage percentage are used for both or one of warp and weft. At least one of the filaments is combined filament yarn of multifilament of 0.5 denier or less in single yarn size formed by splitting composite fiber, and a large number of loops with single yarn of fine size covering the outside are formed on the surface of the cloth. Longitudinal elongation of the cloth receiving drawing action at the time of wiping or polishing is therefore reduced so as to maintain abrasive grain holding force to a free grinding wheel and cushioning performance at the time of pressing abrasive grains.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cloth for wiping or polishing the surface of a medium substrate in a process of manufacturing a magnetic recording medium or the like.

[0002]

2. Description of the Related Art Japanese Patent Publication No. Hei 7-13841,
As described in JP-A-96355, etc., as a magnetic recording medium, conventionally, a substrate made of an aluminum alloy is subjected to a non-magnetic plating treatment such as alumite treatment or Ni-P plating, and then a base layer such as Cr is formed. Coating, then coating with a magnetic thin film layer of a Co-based alloy, and further coating with a carbonaceous protective film are mainly used.

[0003] Such a magnetic recording medium (magnetic disk)
Since the substrate is hard, the dimensional accuracy is high and the recording density is easy to increase because of the rigidity of the substrate. In order to avoid this, the magnetic head is used while flying.

However, as the density of magnetic disks has increased, the flying height of the head has become smaller, and recently, a height of 1.5 μm or less has been required. Keeping the flying height of the head at a very small value is the biggest point in improving the recording density, and the biggest technical challenge is to keep the flying height low and prevent head crash. is there.

On the other hand, when examining a magnetic disk, when writing to or reproducing from the magnetic disk,
When the disk is stationary, suction may occur between the flying surface of the magnetic head and the magnetic disk. When the magnetic head flying surface and the magnetic disk surface face each other at extremely smooth and minute intervals, the above-mentioned adsorption phenomenon occurs when O ₂ , N ₂ , and H ₂ O are interposed therebetween.
This is due to the fact that a large suction force is generated due to the interfacial tension by being buried by such molecules, and when such suction occurs, a disadvantage that a large amount of power is consumed at the time of starting the motor occurs.

In order to prevent such an adsorption phenomenon, prior to forming a magnetic film or the like on the substrate, the surface of the substrate is once made mirror-finished, and then the surface is roughened to an appropriate surface roughness. The texture processing to be adjusted is performed.

As the texture processing method, the following method has conventionally been adopted. That is, using a polishing tape to which abrasive grains of silicon carbide, alumina, or diamond are adhered, and rotating the NiP plating substrate, contacting the polishing tape in the radial direction of the substrate while pressing the polishing tape with a roll from the back side of the tape. By moving the substrate, concentric ridges are formed on the surface of the substrate to obtain a so-called textured substrate.

[0008]

However, with the conventionally used polishing tapes, it is very difficult to roughen the substrate surface by adjusting it to an appropriate surface roughness, and there is a problem that the surface tends to be unnecessarily rough. ing. In order to solve such a problem, Japanese Patent Application Laid-Open No. 6-295432 discloses that the constituent fibers of a polishing tape used for texture processing are made thinner than conventional fibers and have a diameter of 5 μm (thickness of 0.1 denier) or less. It has been proposed to reduce the surface roughness Ra to 40 ° or less by using the following method. JP-A-8-96355 discloses a polishing tape having a water retention of 400% or more, a fiber strength of 11 (kg / 5 cm width) or less at a 10% modulus strength (longitudinal direction) at dry (dry), and , The 1
Dry (dry) of 0% modulus strength (vertical direction) and W
A nonwoven fabric has been proposed in which the difference from et (wet) time is 8 (kg / 5 cm width) or less.

Each of the polishing tapes described in the above-mentioned publications has a characteristic configuration and exerts a specific effect by this. However, the object of the present invention is to further polish the polishing tapes. For wiping and / or fining, which can reduce the surface roughness of the substrate, minimize the occurrence of crashes, and significantly improve the flying characteristics of the magnetic head.
Or in providing a polishing cloth.

Another object of the present invention is not limited to the above-mentioned texture processing, but is also used for burnishing a substrate to be carried out after the processing, and also for manufacturing a disk for recording image information made of a glass disk. It is an object of the present invention to provide a wiping and / or polishing cloth capable of making the substrate surface more uniform than conventional polishing tapes.

[0011]

To achieve the above object, the present invention has the following arrangement. That is, a cloth for wiping or polishing the surface of a substrate such as a magnetic recording medium, which is made of satin weave and has a breaking strength in the vertical direction of 20 kgf / 50 mm or more according to the method A of JIS L 1096.
Tensile elongation is set to 5% / 5 kgf / 50 mm or less, multifilaments are used for the warp, and filaments having different hot water shrinkage rates are used for both or one of the warp yarns, and at least one of the filaments is a split fiber. It is a multifilament mixed yarn having a single yarn fineness of 0.5 denier or less, and a large number of loops covering the outside of the fine fineness single yarn are formed on the cloth surface.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First, the use state of the cloth of the present invention will be described with reference to FIGS. 1 and 2 by taking texture processing as an example. FIG. 1 is a perspective view showing the entire use state, and FIG.
FIG. 2 is a side view of FIG. 1.

As shown in both figures, a total of two cloths 4 and 5 are respectively provided on each of the front and back surfaces 2 and 3 of the substrate 1 which positively rotates in the direction of arrow A, by pressing rolls 6 and 7 respectively. While traveling in the direction of arrow B while being pressed by the above, the polishing liquid containing free abrasive grains is continuously supplied to the respective polishing surfaces of the cloths 4 and 5 from the nozzles 8 and 9 to perform slurry polishing.

Each of the pressing rolls 6 and 7 is driven by a roll processing cylinder 10 and presses the cloths 4 and 5 against the front and back surfaces 2 and 3 of the substrate 1 at a predetermined pressure. Each of the cloths 4 and 5 runs continuously in the direction of arrow B, during which the substrate 1
A new cloth is always supplied to the front and back surfaces 2 and 3 in pressure contact with each other, whereby the front and back surfaces 2 and 3 are polished.

The cloths 4 and 5 reciprocate (vibrate) in the direction of arrow C due to the reciprocating movement of the pressing rolls 6 and 7, respectively, and by this movement and rotation of the substrate 1 itself, ridges are formed on both surfaces of the substrate 1 and the texture is formed. A processed substrate 1 is formed.

The cloth of the present invention is shown in FIGS.
Since the cloth is used under high tension, the ground structure constituting the cloth needs to be not a knitted fabric or a nonwoven fabric but a woven fabric and a satin weave structure. The satin weave is made of more than 5 warp and weft yarns each, and the texture points are scattered on the surface of the woven fabric. One of the warp or weft yarns floats on one side of the woven fabric and covers the fabric surface. It is characterized by its hiding and a smooth surface, and the cloth of the present invention essentially has such characteristics.

In the case of a satin weave, when the number of healds on a loom is large,
For example, the durability of the woven fabric is reduced when ten pieces of satin are used. From this point, it is appropriate to use 5 to 8 pieces of satin for the present cloth.

As the warp constituting the satin weave, multifilaments such as nylon and polyester are used, and in a woven fabric state, the tensile strength (breaking strength) in the warp direction according to the method A specified in JIS L 1096 is 20 kgf. /
50% or more and tensile elongation of 5% / 5kgf / 50m
m is used. Such woven fabric is JIS
In the textile tensile tester specified in 1096, the load 1
It shows an elongation of 0% for kg, 0-0.05% for 2kg, 2% for 3kg, and 5% for 5kg. The warp may be a yarn obtained through a processing process of a false twisting machine, but more preferably a melt-spun drawn yarn as it is, a so-called flat yarn (raw yarn). If the configuration of the warp satisfies the above requirements, it is possible to reduce the elongation in the warp direction of the cloth subjected to the stretching action during wiping or polishing, and it is possible to reduce the abrasive holding force and the abrasive The cushioning property at the time of pressing can be appropriately maintained.

Further, at least one of the warp yarns constituting the satin weave is a single fiber fineness of 0.5 obtained by splitting a composite fiber (conjugate fiber) comprising two or more polymers.
Ultra-fine fibers of less than denier are located. The ultra-fine fibers are obtained by splitting a split-type composite fiber described in JP-B-61-37383 or a sea-island type composite fiber described in JP-B-62-50594. Can be used.

Of these, split-type composite fibers are preferred because they are easy to manufacture and can easily obtain a sharp edge formed on at least one line of the single yarn. Particularly, a fiber obtained by fibrillating (dividing) a composite fiber composed of polyamide and polyester is preferable. The single yarn group obtained from this conjugate fiber is most suitable as the cloth of the present invention because it maintains the dimensional stability of polyester and the hydrophilicity of polyamide at the same time.

The method of fibrillation is described in
A known method described in, for example, Japanese Patent No. 35633 can be used. Among them, a method using benzyl alcohol is preferable.

Various types of split type composite fibers are known. For example, in any cross section of a single filament, a polyamide component and a polyester component have a shape in which one component is joined to the other component without completely surrounding the other component. Composite fiber with side-by-side surface [Fig.
(A)], a side-by-side repeating type conjugate fiber [FIG. 3 (B)], a conjugate fiber comprising a part having a radial shape and another component having a shape complementary to the radiating part [FIG.
(C), (D)], and a conjugate fiber having a hollow portion in the shape [FIG. 3 (E)].

Among these composite fibers, the raw yarn of the cloth of the present invention is a composite fiber comprising a portion having a radial shape and another portion having a shape complementary to the radiation portion [FIG.
(C) and (D)], and, as described above, it is most preferable to use a polyamide as the portion having a radiation-type shape and a polyester as a portion having a shape complementary to the radiation portion.

The composite fibers used in the present invention include:
As described above, those obtained from sea-island type fibers (dissolution splittable fibers) described in JP-B-62-50594 and the like can also be used. As described in the above publications and the like, sea-island fibers are fibers made of at least two kinds of polymers, and the fiber cross section is formed of a sea component and an island component, and the island component is divided into a plurality of sea components.

FIG. 4 shows a cross section of a main sea-island type fiber applied to the cloth of the present invention. In FIG. 4, A1.
2 is an island component and B is a sea component. As the sea-island type polymer in the present invention, two or more polymers having different dissolving and degrading properties with respect to the drug are selected and used, and polyethylene terephthalate, the same copolymer, (isophthalic acid, sodium isophthalate sulfonate, etc.), nylon 6 , Nylon 66, and the like.

Preferred combinations of the above polymers are those in which the sea component polymer is more soluble and degradable by the drug than the island component polymer, or
This is a combination in which only the sea component polymer is completely dissolved without dissolving and decomposing the island component polymer, and the latter is most preferable.

In the case of such a sea-island type fiber, if two kinds of components having different hot water shrinkage rates are used as island components, even after dissolution and removal of the sea component, components having different hot water shrinkage rates can be obtained only with the composite fiber. However, in general, as the number of components increases, the spinning of the composite fiber becomes more difficult. Therefore, when a composite fiber composed of a dissolved component and a single non-dissolved component is used, the hot water shrinkage relative to the non-dissolved component is reduced. It is necessary to use a mixture of different fibers. As such a fiber, it is preferable to use a fiber whose hot water shrinkage is higher than the insoluble component, for example,
20-40% of polyethylene terephthalate copolymerized with modified components such as isophthalic acid and bisphenol
It is preferable because it has the above hot water shrinkage. In the case of such mixed yarns, the fineness yarn appears on the surface and the high shrinkage yarn is located inside by heat treatment as described later, so that the single yarn fineness is 1
Even if a denier or more is used, the effect of the present invention is not inhibited.

As described above, the conjugate fiber constituting at least a part of the cloth of the present invention is divided into individual single yarns for each polymer by a splitting treatment using a chemical after weaving. Form a large number of arc-shaped loops on the cloth surface.

In the case where the constituent polymer of the conjugate fiber is two kinds of polyamide and polyester and the cross-sectional shape is as shown in FIG. 3C, the polyamide shrinks down to the inner layer of the loop layer formed on the cloth surface, The surface layer is substantially covered with polyester of fineness. Of course, the polyester remains in the interior part, but the polyamide shrinks to form a dense structure,
These exhibit a layered structure. As described above, the surface layer portion of the cloth of the present invention is substantially formed of fibrils having a fine fineness, and the surface has a soft touch, while the inner layer portion has a relatively rigid structure. From the multi-layer structure, an effective effect is imparted to the cloth during wiping and polishing, as described later.

In the method shown in FIGS. 1 and 2, a slurry containing loose abrasive grains is supplied between the cloths 4 and 5 of the present invention and the substrate 1, and the slurry is applied to the cloths 4 and 5 immediately before the slurry grinding. However, the slurry may be applied in advance on a cloth.

By using the cloth of the present invention, the average roughness of the textured substrate surface can be made in the range of 10 to 20 °, more preferably 10 ° or less.

As described above, the cloth of the present invention comprising the warp and the weft has a texture of satin weave, and at least one of the constituent yarns is formed of a specific range of single yarn denier. The contact surface can be made very soft. Further, since the warp is formed of a specific yarn, the warp has durability against elongation in the longitudinal direction, and does not cause poor polishing due to unnecessary elongation of the cloth.

Further, since one of the yarns used in the present invention is formed of two or more kinds of polymers having different hot water shrinkage ratios, the heat treatment makes it possible to obtain various fine arc-shaped loops caused by the difference in the heat shrinkage ratio. Can be formed evenly in the longitudinal direction of the cloth, and this loop has a resilient function and comes into contact with the substrate surface at the time of wiping and polishing, which has the effect of further increasing the smoothness of the surface.

In the above-described embodiment, an example in which the cloth of the present invention is used for texture processing has been described. The cloth of the present invention is effectively used in place of the wrapping tape. The use example in this case is carried out in the process shown in FIGS. 1 and 2 in the same manner as the texture processing, and the average roughness of the substrate surface can be further improved as compared with the conventional wrapping tape.

[0035]

The present invention will be further described below with reference to examples. Using abrasive grains having an average particle size of 0.5 μm or less and five types of cloths having the structures shown in Table 1, commercially available Ni—P alloy-plated aluminum substrates were used as shown in FIGS.
The texture processing was performed by the method shown in FIG. Next, the five types of substrates subjected to the texture processing were subjected to cleaning and sputtering, respectively, and then subjected to burnishing using the same cloth as that used for the texture processing to obtain a completed magnetic disk. The average roughness of the surface of the obtained magnetic disk was measured. Table 1 shows the results.

[0036]

[Table 1]

In the polymer representation in Table 1, PE indicates polyester and N indicates nylon, and the N / PE composite yarn used for the weft is the composite yarn shown in FIG.
The radial portion is made of nylon, and the eight segments that complement it are made of polyester, and are sold by one of the applicants under the trade names Verima X (standard single yarn fineness of 2 denier) and Verima SX (standard single yarn fineness of 1). Denier).

As shown in Table 1, the surface roughness of the magnetic disk obtained is preferably as small as the single-filament fineness, and in the comparative example, elongation occurs in the longitudinal direction due to the tension applied to the cloth.
Further, in the four-sided satin weave structure of Example 2, one-sided flow of the slurry occurs during polishing, and there is a difference in average roughness between the central portion and the outer peripheral portion of the substrate. This can be improved by brushing,
There is a drawback that a slightly generated flaw is conspicuous. Practically, all of the examples were effective. The surface roughness described in the present specification is a surface roughness defined in JIS B0601.

[0039]

As described above, by using the cloth of the present invention for texture processing or burnishing processing, which is a manufacturing process of a magnetic recording medium or the like, the surface roughness of the substrate surface can be dramatically improved easily and appropriately. At the same time, it is possible to minimize the occurrence of crashes, which greatly contributes to solving the technical maximum problem described at the beginning.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a use state of a cloth according to the present invention.

FIG. 2 is a side view showing a use state of the cloth according to the present invention.

FIG. 3 is a cross-sectional view of a splittable conjugate fiber used in the present cloth.

FIG. 4 is a cross-sectional view of the sea-island composite fiber used in the present cloth.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 front surface (substrate) 3 back surface (substrate) 4,5 cloth 6,7 pressing roll 8,9 nozzle 10 cylinder

Claims (1)

[Claims] 1. A cloth for wiping or polishing the surface of a substrate such as a magnetic recording medium, the cloth being made of satin weave,
The breaking strength in the vertical direction by the method A of SL 1096 was 2
0kgf / 50mm or more, tensile elongation 5% / 5kgf
/ 50 mm or less, multifilaments are used for the warp, filaments having different hot water shrinkage rates are used for both or one of the warp yarns, and at least one of the filaments is a single fiber fineness of 0 obtained by splitting a conjugate fiber. .5
A cloth used for manufacturing a magnetic recording medium or the like, wherein the cloth is a multifilament yarn having a denier or less and has a large number of loops on the surface of the cloth which are covered with a fineness single yarn.