JP2001067659A - Magnetic recording medium processing tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium processing tape which is capable of applying highly accurate texturing on the surface of a substrate with good yield. SOLUTION: The magnetic medium processing tape is a sheet in which a high polymer elastic body is imparted to an entangled body consisting of extremely thin fibers of <=0.05 dtex in size and which has fluffing surface consisting of the extremely thin fibers at least on one side. The length of the fluffing is controlled to be <=1 mm, the apparent density is controlled to be >=0.3 g/cm3 and the R value, which is obtained with a formula, R value (%)=(R1-R3)/(R1-R2)×100 (where, R1: the quantity of reflected light at 0 deg., R2: the minimum quantity of reflected light within the rotation range of 0 to 180 deg., R3: the quantity of reflected light at 180 deg.) from an angle changing reflection curve measured with an automatic angle changing photometer by rotating a fluffing surface 0 to 180 deg., is controlled to be <=25%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium processing tape capable of performing high-precision texturing on a substrate surface.

[0002]

2. Description of the Related Art Magnetic recording media, such as magnetic disks, have been increasing in capacity due to remarkable technological innovation in recent years.
There is an increasing demand for higher recording densities, which requires higher densification of substrate surface processing. That is, the surface roughness (hereinafter, referred to as Ra) and the maximum projection height (hereinafter, referred to as Rp) are minimized. For this reason, Japanese Unexamined Patent Application Publication No.
In Japanese Patent Publication No. 2 (KOKAI), a knitted-type cloth obtained by weaving fibers having a diameter of 5 μm or less is used as a tape to improve these properties. Japanese Patent Application Laid-Open No. Hei 10-188272 discloses a method using a woven cloth, a nonwoven cloth, a flocking, or a knitted material tape of ultrafine fibers of 0.1 denier or less with the same concept. However, even if processing using a tape consisting of such conventional ultrafine fibers themselves, the directionality of the nap of the ultrafine fibers present on the tape surface is remarkable, and
The length is not uniform, the finishing accuracy tends to vary, and the scratch defect is apt to occur. The problem is inherent in the production yield, and the surface roughness Ra is around 20. There was a limit to processing. The characteristics required for such a polishing tape are polishing rate, uniformity, surface roughness, and the like. From the viewpoint of productivity, reproducibility and long life are also important. In particular, as the surface roughness, Ra defined in JIS B0601 is a standard. This Ra is aimed at 20 angstroms or less, and further, 15 angstroms or less. However, from an industrial point of view, a tape for texturing that satisfies these requirements is not yet in a satisfactory state.

[0003]

SUMMARY OF THE INVENTION In view of the background of the prior art, the present invention provides a tape for processing a magnetic recording medium having a good yield and capable of performing high-precision texturing on a substrate surface. is there.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, in order to achieve the required characteristics of the polishing tape, the nap on the surface of the nap sheet has a specific property. Was found to be important. That is, the magnetic recording medium processed tape of the present invention is a sheet in which a polymer elastic body is provided to an entangled body having a microfiber having a thickness of 0.05 dtex or less and a raised surface made of the microfiber is provided on at least one surface. The nap length is 1 mm or less, the apparent density is 0.3 g / cm ³ or more, and the angle-change reflection curve measured by rotating the nap surface from 0 to 180 degrees with an automatic angle-variable photometer, the following formula is obtained. R value obtained by
% Or less. R value (%) = (R ₁ −R ₃ ) / (R ₁ −R ₂ ) × 100 where R ₁ : the amount of reflected light at 0 degree R ₂ : the minimum amount of reflected light in the 0 to 180 degree rotation range R ₃ : Reflected light amount at 180 degrees.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, a sheet in which a polymer elastic body is provided to an entangled body made of microfibers and at least one surface of which has a raised surface made of microfibers is used in a raising process, for example, by using sandpaper to obtain a sheet surface. Is raised in the vertical direction of the sheet by buffing. At this time, directionality is given to the napped hair by the buffing direction. Here, the direction in which the nap is likely to fall when the nap surface is stroked with a brush is defined as a forward direction, and the direction in which the nap occurs occurs is defined as a reverse direction.

FIG. 1 shows a method of measuring a bending reflection curve according to the present invention.
This will be described with reference to the model diagram shown in FIG.

First, a halogen lamp (1) is used as a light source lamp.
Automatic goniophotometer (GP-20 equipped with 2V, 50W)
0 type), the incident light (i) is directed toward the center point (O) with respect to the normal (N) of the surface of the napped sheet (S), the incident angle (α) is 60 degrees, and the reflected light (R) is used. Is 60 degrees. Next, the material is nylon (210D-15f,
Using Toray) filament, vertical warp × horizontal weft = 8
5 × 57 / in, number of piles = 594/25 mm ² , pile length = 2.6 mm (thickness from back of fabric to tip of pile)
Double pile fabric, heat set, brush fabric with pile pile in one direction, weigh 400 g length ×
A material having a flat surface having a width of 10 × 10 cm and fixed by a load is placed on the raised surface of the napped sheet and stroked at a speed of about 5 m / min in the forward direction of the napped. This operation is repeated five times to obtain a measurement sample. This sample is set so that the positive direction (a) of the nap is perpendicular to the incident light (i) as shown in FIG. The sample angle at this position is set to 0 degree.
At this time, the nap sheet is continuously rotated in the direction of the arrow by 180 degrees simultaneously with the application of the light source, and the reflected light (R) is continuously measured to obtain a deflection reflection curve. However, when the napped sheet is colored, the amount of reflected light on the variable angle reflection curve naturally differs even with the same amount of light depending on the hue of the surface. Therefore, the reference conditions for calculating the R value (%) shown in the present invention are those measured under the following conditions. First, using a magnesium fluoride white plate, the full scale is adjusted to 100% using light intensity adjustment and sensitivity adjustment of the apparatus. Next, for example, when a dark-colored napped sheet is set under the above conditions, the amount of reflected light naturally changes to a low position. Further, when a light-colored product of the napped sheet is set under the above conditions, the amount of reflected light shifts to a position higher than that of a dark-colored product. In order to eliminate such a difference due to the hue of the napped sheet and to perform evaluation using the same standard, the napped sheet was set so that the positive direction (a) was perpendicular to the incident light (i) (the sample angle was 0 degree). The measurement is started after adjusting the aperture of the light amount and the sensitivity of the apparatus so that the reflected light amount at the time comes to the position (X) of 50% of the magnesium fluoride white plate, and the deflection angle reflection curve as shown in FIG. 2 is obtained. Using this, the R value (%) is determined by the calculation formula described in the present invention. This will be described in more detail using an example of a variable reflection curve.

In the present invention, R ₁ refers to R ₁ on the variable-angle reflection curve in FIG. 2, that is, the reflected light amount at which the light source hits the upright in the positive direction at 90 degrees. Further, R ₂ means that the napped sheet is rotated at a constant speed by 180
Rotate continuously to the degree
₃ when rotated 180 degrees and, that is, the amount of reflected light in the direction exactly the reversed position of the napped in R _1.

In the present invention, the light amount difference of (R ₁ -R ₂ ) is set to 100% in the deflection angle reflection curve of the napped sheet surface, and (R
_When the R value (%) obtained as to what percentage of the light amount difference of ₁ -R ₃ ) is 25% or less, preferably 20% or less, more preferably 15% or less, local aggregation of the slurry is moderated. In addition, the occurrence of scratch defects can be suppressed, the yield can be improved, and high-precision texture processing can be performed on the substrate surface.

The characteristic of the sheet provided with the polymer elastic body having such an R value (%) and having a raised surface made of ultrafine fibers on at least one side is that the ultrafine fibers of 0.05 dtex or less are entangled. It is important to make up the nonwoven structure.

In obtaining such a nonwoven fabric, a general method can be employed. For example, after forming ultra-short fibers into a sheet according to a papermaking method, the fibers are entangled with each other by using a thin columnar flow of high-pressure water, or the fibers stretched finely using the accompanying force of a high-speed fluid during spinning. And the like, and a method using a sheet formed by depositing the same can be adopted. A more preferable method is to adopt a method using a composite fiber as described below. The conjugate fiber in such a method is, for example, using a polymer of at least two components having different properties from each other, spinning a conjugate fiber of a polymer mutual arrangement type, a sea-island type, a release type, a multilayer type, etc., forming a short fiber into a web, and forming a needle A nonwoven fabric is formed by applying an entanglement means such as a punch or a water jet punch, and thereafter, at least one component is dissolved and removed or separated and separated by physical or chemical action to obtain an ultrafine fiber of 0.05 dtex or less. Can be.

As the polymer forming the ultrafine fibers in the present invention, polyamide, polyester, polyphenylene sulfide, polyolefin, polyacrylonitrile, polyimide and the like can be used. Is preferred from the viewpoint of stability upon contact with water. In order to form a composite fiber for obtaining such an ultrafine fiber,
Consider spinnability, stretchability, etc. of the above ultrafine fiber forming polymer by dissolving and removing or separating and splitting by physical or chemical action, such as polyolefins such as polyamides, polyesters, polyethylene, polystyrene and polypropylene. After that, they can be combined.

In forming the magnetic recording medium processing tape of the present invention, the above-mentioned ultrafine fiber or composite fiber is formed into a sheet, and then a polymer elastic body is provided.

As the polymer elastic body, polyurethane, acrylic polymer, silicone rubber and the like can be used, and among them, polyurethane is particularly preferable. Even in such polyurethane, as its soft segment,
Polyester diols, polyether diols, polycarbonate diols, or those linearly segmented or partially cross-linked such as copolymers thereof can be used alone or in combination depending on the purpose. However, in particular, a polyether alone such as polytetramethylene glycol and polypropylene glycol, or a polyurethane obtained by copolymerizing the same with 30% or less of polyester or polycarbonate can be preferably used because scratch can be avoided.

In the present invention, the amount of the elastic polymer in the sheet of ultrafine fibers is 20 to 8 with respect to the weight of the ultrafine fibers.
0% by weight is preferable, and more preferably 30 to 70% by weight.
Is good. When the amount is less than 20% by weight, the napped fibers of the ultrafine fibers easily fall out during polishing of the substrate, and when the amount exceeds 80% by weight, the sheet becomes hard and lacks compression elasticity, which is not preferable.

After the nonwoven fabric sheet is impregnated with such a polymer elastic body, it is wet-solidified in water, dried, and if necessary cut in half in the thickness direction, and at least one surface is buffed using sandpaper or the like. A sheet having a napped surface made of ultrafine fibers is obtained,
The magnetic recording medium processing tape of the present invention, which has a good yield and can perform high-precision texturing on the substrate surface, preferably has an increased apparent density and a fiber-rich surface as much as possible. .3g / cm ³ or more, preferably to the 0.4 g / cm ³ or more. Means for increasing the apparent density of the ultrafine fibers include increasing the fiber shrinkage of the conjugate fiber that generates the ultrafine fibers, increasing the area shrinkage of the entangled body, and then compressing, using a solvent or swelling agent for the polymer elastic body. It can be achieved by appropriately combining a method of applying to a sheet and then compressing or a method of applying a solvent or swelling agent of a polymer elastic material to the raised surface and compressing. 0.3g / cm ³ apparent density
When the value is less than the above, irregularities on the nap surface are likely to occur, and the polymer elastic body tends to be exposed on the surface, and the nap direction becomes tight. Further, 9 on the reflection curve as shown in FIG.
At around 0 degrees, a difference occurs due to a change in the amount of reflected light between the two, and local distortions such as fine irregularities and undulations of the magnetic recording substrate during texture processing cannot be completely absorbed, and scratches and local roughness may be poor. In order to solve these problems, the R value (%) is set to 25% or less as shown in FIG. 3, and when the sample surface is further rotated around 90 degrees, the reflection curve shown in FIG. It is important that there is almost no difference caused by the change of the two reflected light amounts around 90 degrees. That is, if the change in the amount of reflected light is small at around 90 degrees, the directionality of the napped hair is extremely small, and stable texture processing can be performed.

In order to further enhance the effect of the present invention, it is preferable to shorten the nap of the ultrafine fibers. The nap length is 1 mm or less, preferably 0.5 mm or less. When it is 1 mm or more, the direction of the nap is sharp, the R value (%) becomes high, and the gripping property of loose abrasive grains is improved, but there is a tendency that the roughness is lacking. Worse. The length of the nap can be measured from an enlarged photograph of the tape surface or side surface by an electron microscope (SEM). Means for obtaining such a napped state include, for example, increasing the buffing speed, making the coating particles fine with sandpaper, or increasing the adhesiveness between the ultrafine fiber bundle and the polymer elastic body, and then buffing, or the sheet surface. This can be achieved by applying a suitable combination of methods such as applying fine inorganic fine particles with a brush, increasing the frictional resistance, and buffing at a high speed.

When the ultrafine fiber forming polymer of these napped sheets is a polyester or a copolymer thereof,
By appropriately reducing the amount of microfibers with an alkaline solution, opening the gap between the naps and narrowing the nap tips, or, in the case of polyamides, by pre-treating with a swelling agent and rubbing in the liquid , R value (%) can be reduced, and more preferable values are obtained. In addition, tension is applied to the tape via a rubber roller etc. during texture processing,
When the tape is run while being pressed against the polishing substrate, the tape may be stretched or twisted.

The sheet having a raised surface according to the present invention also solves these problems. In a preferred embodiment, the entangled body made of ultrafine fibers of 0.05 dtex or less is entangled with a woven or knitted fabric. The integrated sheet has a structure in which a polymer elastic body is provided. At least one surface has a nap length of 1 mm or less, an apparent density of 0.3 g / cm ³ or more, and the nap surface is measured by an automatic goniophotometer. 0 degrees to 1
R obtained from the bending angle reflection curve measured by rotating by 80 degrees
By setting the value to 25% or less, the disadvantages of the prior art can be eliminated. As a method of forming a napped sheet having such a structure, a web of the above-described conjugate fiber is laminated on a woven or knitted fabric, and entangled and integrated by a needle punch, a water jet punch, or a combination thereof. As a laminating method, a woven or knitted fabric is laminated on both sides or one side of the web and entangled, or the web is laminated and entangled on one side, and a plurality of the entangled bodies are further laminated and entangled again.

In the present invention, as the yarn type constituting the woven or knitted fabric, filament yarn, spun yarn, or blended yarn of filament and short fiber can be used, but is not particularly limited thereto. Also, as the type of woven or knitted fabric, weft knitting represented by warp knitting, tricot knitting, lace knitting and various knitting based on those knitting, or plain weave, twill weave, satin weaving and their weaving are basically Although various woven fabrics can be used, plain weave, twill weave, satin weave and the like are particularly preferable from the viewpoint of tape elongation and twist prevention. Depending on the yarn type, when the entanglement between the conjugate fiber and the woven or knitted fabric is strengthened by needle punching, the fiber is easily cut, and the cut thick fiber is mixed with the nap surface, causing scratches on the polished substrate surface. . As a means for preventing this, it is preferable that these yarn types are strong twist yarns. The number of twists of the strong twist yarn is preferably 500 T / m or more and 4500 T / m or less, more preferably 1500 T / m or more and 2000 T / m or more.
T / m or more is most preferable. If it is less than 500 T / m, the single yarns constituting the yarn are insufficiently squeezed, so that the yarns are liable to be caught by the needle and easily damaged, and the fiber is too hard even if the number of twists is too large, and the nap is made. It is preferably 4000 T / m or less from the viewpoint that irregularities easily occur on the surface.

In the present invention, the fibers constituting the woven or knitted fabric include polyesters, polyamides, polyethylene, polypropylene and copolymers thereof. Among them, polyesters, polyamides and copolymers thereof are preferably used alone or in combination. By adopting such a structure, even when cut into narrow tapes, the tape width is constant and there is no dimensional change,
This enables stable texture processing.

As described above, in the present invention, such a napped sheet is cut into a tape shape and used as a textured tape. This processing is a texture processing for a magnetic recording medium using free abrasive grains, and the feature of the tape material for processing a magnetic recording medium of the present invention is that even in such processing, the scratch defect is extremely small and the surface roughness is stable. In order to enable small-size machining, high-performance and high-yield machining is enabled. Also, in this texture processing, before applying the slurry to the tape,
Liquid or slurry containing abrasives in advance, or a liquid containing a surfactant, or a commonly used grinding oil, etc. should be applied in advance to make it easy to disperse the free abrasive slurry uniformly over the entire surface of the tape. It is preferable from the viewpoint of processing stability.

[0024]

The present invention will be described below in detail with reference to examples.

[0025]

Example 1 Polyethylene terephthalate as island component, polystyrene as sea component, island / sea ratio = 30/70% by weight,
36 islands, composite fiber denier about 4d, cut length about 51
A staple of a polymer inter-arrayed fiber having a mm and a shrinkage number of about 12 peaks / in was used, and the staple was formed into a web with a card cross wrapper and needle punched to produce a felt. The felt was subjected to shrinkage treatment, dried, polyvinyl alcohol was applied, dried, immersed in trichlene, squeezed with a mangle, and dried. In this sheet, the soft segment has a ratio of polytetramethylene glycol to polycarbonate of 70: 3.
0, the isocyanate was diphenylmethane diisocyanate, and a polyurethane using ethylene glycol as a chain extender was impregnated as a solid content at about 30 parts per island fiber, and wet coagulated. Then, it is immersed in a 90% by weight aqueous solution of dimethylformamide and compressed with a clearance of about half the thickness, immersed in water, solvent is removed, dried, and dried to a thickness of 0.05 d.
A sheet was obtained in which a polymer elastic body was added to a bundled entangled body of ultrafine fibers of polyethylene terephthalate of tex. This sheet was cut in half in the thickness direction, and the non-cut face was raised with a 320 mesh sandpaper.

Next, the greige fabric was put into a circular dyeing machine, subjected to hot-water baking treatment, and had an apparent density of 0.41 g / cm.
^3. A napped sheet having a napped length of 0.7 mm was obtained.

The napped sheet is cut into a length × width = 5 × 5 cm, and the napped surface is rubbed with an etiquette brush (registered trademark) five times in the forward direction. Rotation was performed continuously by 180 degrees, and the deflection reflection curve was measured. The R value obtained from the variable angle reflection curve was 15%, and had almost no difference caused by the change in the two reflected light amounts at around 90 degrees on the reflection curve as shown in FIG. This napped sheet was cut into a width of 35 mm and a length of 50 m to prepare a tape-shaped napped sheet. Next, texture processing was performed under the following conditions.

After Ni-P plating on the aluminum plate,
Using a polished base, a slurry was prepared by dropping a free-alumina slurry having an average particle size of 0.2 μm based on white alumina at a rate of 10 mL / min. / Min, amplitude 1mm
At 500 times / min.

As a result, the surface roughness Ra was 11.1 angstroms (standard deviation 1.2), there was no scratch,
Very good results were obtained.

[0030]

Example 2 A web made of the same staples of the polymer mutually aligned fibers as in Example 1 was laminated on a plain woven fabric of 75D-72f of polyethylene terephthalate and a false twist yarn of 2500 T / m using a raw yarn false twisted yarn. I made felt. Thereafter, the sheet was treated under the same conditions as in Example 1 to obtain a sheet in which polyurethane was applied to a fiber entangled body in which an ultrafine fiber bundle made of polyethylene terephthalate having a thickness of 0.05 dtex and a woven fabric were entangled and integrated. This sheet was cut in half in the same manner as in Example 1, the half cut surface was subjected to a brushing treatment and a hot water buffing treatment was carried out to obtain a raised sheet having an apparent density of 0.44 g / cm ³ and a nap length of 0.7 mm. The R value obtained from the bending reflection curve of this napped sheet measured in the same manner as in Example 1 was 12%, and the two reflected light amounts at around 90 degrees on the same reflection curve as in Example 1 were obtained. There was almost no difference that occurred. 35m width of this napped sheet
m, and cut to a length of 50 m to produce a tape-shaped raised sheet. Next, texture processing was performed under the same conditions as in Example 1 except that a diamond-based slurry was used as the loose abrasive slurry for this tape. As a result, the surface roughness R
a was as excellent as 12.6 angstroms (standard deviation 0.9).

[0031]

Comparative Example 1 The island component was polyethylene terephthalate, the sea component was polystyrene, the island / sea ratio was 60/40% by weight,
16 islands, composite fiber denier about 4d, cut length about 51
A staple of a polymer inter-arrayed fiber having a mm and a shrinkage number of about 12 peaks / in was used, and the staple was formed into a web with a card cross wrapper, followed by needle punching to produce a felt. The felt was subjected to shrinkage treatment, dried, polyvinyl alcohol was applied, dried, immersed in trichlene, squeezed with a mangle, and dried. This sheet is impregnated with a polytetramethylene glycol-based polyurethane as a solid content in an amount of about 15 parts per island fiber, wet-coagulated, solvent removed, and dried.
A sheet was obtained in which a polymer elastic body was added to a bundled entangled body of ultrafine fibers of polyethylene terephthalate having a thickness of 0.20 dtex. This sheet was cut in half in the thickness direction, and the cut surface was brushed with a 150-mesh sandpaper.

Next, this green machine was put into a circular dyeing machine, subjected to hot-water baking treatment, and had an apparent density of 0.21 g / cm.
^3. A napped sheet having a napped length of 1.3 mm was obtained. The R value obtained from the bending angle reflection curve of this napped sheet measured in the same manner as in Example 1 was 37%, and the change in two reflected light amounts at around 90 degrees on the reflection curve as shown in FIG. The differences caused by were significant. This napped sheet was cut into a width of 35 mm and a length of 50 m to prepare a tape-shaped napped sheet. Next, texture processing was performed under the same conditions as in Example 1. As a result, the surface roughness Ra was as high as 25.6 angstroms (standard deviation 1.3), and detachment of the nap fibers was recognized.

[0033]

[Table 1]

[0034]

According to the tape for processing a magnetic recording medium having naps of the present invention, unlike the conventional nap-applied tapes, the nap orientation is extremely small, so that stable and high-precision texturing can be performed. Therefore, a uniform and smooth magnetic recording medium can be stably provided.

[Brief description of the drawings]

FIG. 1 is a model diagram of a measuring method of a deflection angle reflection curve referred to in the present invention.

FIG. 2 is an example of a deflection reflection curve of the conventional napped sheet shown in Comparative Example 1.

FIG. 3 is an example of a deflection reflection curve of the napped sheet of the present invention shown in Example 1.

[Explanation of symbols]

S: Sample surface i: Incident light R: Reflected light α: Incident angle γ: Light receiving angle N: Normal line of the sample surface O: Center point a: Direction of raised hair R ₁ : Reflected light amount at 0 degree R ₂ : 0 degree minimum amount of reflected light R at 180 degrees rotation range _3: the amount of reflected light at 180 degrees

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C063 AA03 AB07 BG01 BG08 BG22 EE01 EE26 FF23 5D112 AA02 AA24 BA06 GA13

Claims (4)

[Claims] An entangled body having ultrafine fibers having a thickness of 0.05 dtex or less is provided with a polymer elastic body, and at least one surface thereof has a nap surface made of the ultrafine fibers, and the nap length is 1 mm. Hereinafter, the apparent density is 0.3 g / cm ³
Above, and the napped surface was set to 0 by the automatic surface goniophotometer.
A tape for processing a magnetic recording medium, wherein an R value obtained by the following equation from a deflection reflection curve measured by rotating the tape by 180 degrees is 25% or less. R value (%) = (R ₁ −R ₃ ) / (R ₁ −R ₂ ) × 100 where R ₁ : the amount of reflected light at 0 degree R ₂ : the minimum amount of reflected light in the 0 to 180 degree rotation range R ₃ : Reflected light amount at 180 degrees. 2. An entangled body having an ultrafine fiber having a thickness of 0.05 dtex or less is entangled and integrated with a woven or knitted fabric;
A sheet having a raised surface made of the ultrafine fiber on at least one side, having a raised length of 1 mm or less, an apparent density of 0.3 g / cm ³ or more, and an automatic bending angle luminous intensity. From the deflection reflection curve measured by rotating the napped surface by 0 to 180 degrees with a meter, R
A tape for processing a magnetic recording medium, wherein the value is 25% or less. R value (%) = (R ₁ −R ₃ ) / (R ₁ −R ₂ ) × 100 where R ₁ : the amount of reflected light at 0 degree R ₂ : the minimum amount of reflected light in the 0 to 180 degree rotation range R ₃ : The amount of reflected light at 180 degrees 3. At least a part of the constituent yarns of the woven or knitted fabric has a number of twists of not less than 500 twists (hereinafter referred to as T) / m and not less than 45.
3. The magnetic recording medium processing tape according to claim 1, wherein the tape is made of a strong twisted yarn of 00 T / m or less. 4. The tape for processing a magnetic recording medium according to claim 1, wherein the elastic polymer is made of polyurethane containing a unit selected from polyether and polycarbonate.