JP2006155758A - Method for treating tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating a tape by which a stable curved shape is imparted also to the outer periphery side of a wound body (pancake) and deviation of the wound body of a tape and variation of a tape width in the case of thermal treatment are prevented. <P>SOLUTION: The method for treating the tape produces the pancake 1 by winding a magnetic tape MT on a hub 11 having a tapered winding surface 11c and thermally treats the pancake 1. When the pancake 1 is produced, the hub 11 having a diameter L1 which is ≥0.5 times longer than the diameter L3 of the outer periphery of the wound body is used. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for processing a tape, and more particularly, to a method for processing a tape that prevents disturbance (winding disturbance) in a winding form of a tape wound around a tape reel.

  In general, for example, a linear or helical magnetic tape having a width of 12.65 mm is widely used as an external recording medium for data backup such as a computer. This magnetic tape is handled in a state where it is wound around a tape reel. However, when the magnetic tape is wound around the tape reel in a winder or drive, the position of the end face of the tape edge tends to be uneven (so-called winding disturbance). In particular, in high-speed winding, remarkable turbulence often occurs. Such turbulence is liable to cause edge damage during transportation, and bad winding habits occur during storage, which deteriorates tape running accuracy in the drive and causes servo tracking abnormality. For this reason, it is important to ensure a satisfactory winding shape at the time of shipment and to produce a magnetic tape that is less likely to cause winding disturbance in the drive, in order to guarantee the required performance of the product.

Conventionally, it is known that when a winding tape having a predetermined curved shape is attached to a magnetic tape, a good winding shape is ensured, the running of the tape is stabilized, and the servo tracking performance is improved. FIG. 4 is a plan view of a magnetic tape having a curved shape. As shown in FIG. 4, for example, when the magnetic tape MT is formed so as to be bent from a reference line connecting both end edges in the length direction, a good winding shape is obtained. On the other hand, if a certain curved shape cannot be obtained, the winding shape deteriorates. Accordingly, various techniques have been proposed for attaching a curl that has a predetermined curved shape with which a good winding shape can be obtained (see, for example, Patent Documents 1 and 2).
Note that the maximum distance D from the reference line to the curved edge with respect to the specified length L is expressed as a bending amount (D / L).

  Patent Document 1 describes a technique for applying a curl by using a reel hub having a taper winding surface in a magnetic tape manufacturing process and leaving the magnetic tape in a state of being wound on the reel hub for a predetermined time. Has been. According to this, the magnetic tape wound up on the diameter-enlarged end side of the reel hub is stretched, and a curved winding rod is attached.

Patent Document 2 describes a technique in which a magnetic tape is wound around a taper-shaped reel hub, and a curved winding rod is attached by storing the tape at a temperature lower than the glass transition temperature. According to this, the curl is easily fixed on the magnetic tape, and a good winding shape can always be secured.
JP-A-9-138945 (Claim 1, paragraphs 0019 to 0021, FIG. 2) JP 2004-164808 A (Claim 1, paragraph 0039)

However, in the technique described in Patent Document 1 described above, as the magnetic tape is rolled up, the outer circumference of the wound ball of the tape is caused by an air layer between the tapes, accumulation of thickness differences in the tape width direction, or minute burrs on the edges. There is a problem that the shape of the reel hub is hardly reflected on the side and it is difficult to obtain a stable curved shape. In addition, the curved shape obtained also varies due to variations in tape length that may occur in manufacturing and variations in the reel hub.
Further, the technique described in Patent Document 2 has a problem in that a gap is generated between the tapes mainly in the vicinity of the middle circumference of the wound ball due to the influence of heat shrinkage during the heat treatment, and the wound ball is easily displaced. If the wound ball is displaced, the tape surface may be damaged or the subsequent process may be impossible. Furthermore, there is a problem that the inner peripheral side of the wound ball of the tape is crushed by winding the magnetic tape during the heat treatment, and the tape width is increased toward the inner peripheral side.

  Therefore, in the present invention, the above-described problems can be solved, a stable curved shape can be imparted also to the outer peripheral side of the wound ball, and the deviation of the wound ball of the tape and the fluctuation of the tape width during heat treatment can be prevented. An object of the present invention is to provide a method of processing a tape that can be used.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a tape processing method in which a tape is wound around a hub having a tapered winding surface to produce a wound ball, and the wound ball is heat-treated. In the production of the wound ball, a hub having a diameter of 0.5 times or more with respect to the diameter of the outer periphery of the wound ball is used.

  According to the first aspect of the present invention, the number of windings of the tape around the hub can be suppressed by using a hub having a diameter of 0.5 times or more with respect to a ball of a desired size. Thereby, the outer peripheral side of the wound ball also easily reflects the shape of the hub, and a stable curved shape is also given to the outer peripheral side of the wound ball. Further, when the wound ball is heat-treated, the greater the number of windings, in other words, the greater the distance from the inner periphery to the outer periphery, the more the stress in the longitudinal direction of the magnetic tape decreases near the middle periphery. Then, the said space | interval becomes narrow by enlarging the magnitude | size of a hub and suppressing the frequency | count of winding of a tape. For this reason, a decrease in stress in the vicinity of the middle circumference is suppressed, and the winding ball is less likely to be displaced. Furthermore, since the number of windings of the tape is suppressed, the tightening stress applied to the inner periphery of the wound ball by heat treatment is small, and the tape width change (spread deformation) caused by crushing the inner periphery is suppressed. It is done.

  According to a second aspect of the present invention, in the tape processing method according to the first aspect, a winding tension for winding the tape around the hub is 0.8 N / cm (≈100 gf / 0.5 inch) or more.

  According to the invention described in claim 2, in addition to the action of the tape processing method described in claim 1, the winding tension per unit width is set to 0.8 N / cm or more. Increasing the winding tension is thought to increase the stress due to tightening and increase the tape width, but when pulled, the contribution of the effect of narrowing the tape width due to the material balance is greater. This will be clarified in an embodiment described later.

According to a third aspect of the present invention, in the tape processing method according to the first or second aspect, the wound ball is heat-treated under conditions that satisfy the following mathematical formula.
t ≧ kT ^-5
However, t: time (H), k: coefficient, T: treatment temperature (° C.).

  According to the third aspect of the invention, in addition to the action of the tape processing method according to the first or second aspect, predetermined heat treatment conditions are satisfied. When this heat treatment condition is satisfied, a practically sufficient curved shape is imparted to the tape. This will be clarified in an embodiment described later. T (treatment temperature) is set to a temperature not higher than the glass transition temperature of the support constituting the tape.

  According to such a tape processing method, the number of times the tape is wound around the hub can be suppressed, and a stable curved shape can be imparted to the outer peripheral side of the wound ball. Thereby, the favorable winding form of a tape is securable. In addition, by suppressing the number of windings, when the wound balls are heat-treated, the stress in the longitudinal direction of the magnetic tape in the vicinity of the middle circumference of the wound balls is less likely to decrease, so that the displacement of the wound balls can be prevented. Furthermore, by suppressing the number of windings, the tightening stress applied by the heat treatment is also reduced, so that deformation (expansion of the tape width) caused by crushing the tape can also be prevented.

  Next, an embodiment of a tape processing method according to the present invention will be described in detail with reference to the drawings as appropriate. The tape processing method according to the present embodiment is a processing method for imparting a predetermined curved shape to the magnetic tape, and a winding process for producing pancakes (roll balls) from a web that is a magnetic tape raw material, And a heat treatment step for heat treating the pancake.

(Magnetic tape stock)
First, before explaining each process, the magnetic tape raw material for pancake preparation is demonstrated. The original magnetic tape is configured by forming a magnetic layer on a nonmagnetic support (base film) having a total thickness of 10 μm or less.

  Examples of the support material include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefins such as polypropylene, cellulose derivatives such as nitrocellulose, polyamide, polyimide, polyvinyl chloride, polycarbonate, and aramid. Etc. can be used. For the support, it is desirable to use polyesters that are excellent in processability and mechanical properties and low in cost. Among these, it is desirable to use polyethylene naphthalate (PEN) having high strength, rigidity and heat resistance. Moreover, when more heat resistance is required, it is desirable to use aramid.

  The magnetic layer is formed by applying a magnetic coating material prepared by mixing magnetic powder, a binder and an organic solvent until the magnetic powder is uniformly dispersed on a non-magnetic support. Alternatively, the magnetic layer is formed by depositing a ferromagnetic material such as a metal or an alloy on the support by means such as vacuum deposition or sputtering. The thickness of this magnetic layer is 0.5 μm or less in order to cope with the recent increase in density. In addition, a dispersant, a lubricant, an antistatic agent, a plasticizer, a stabilizer, and a rust preventive agent are added to the magnetic paint.

Examples of the magnetic powder include ferromagnetic iron oxide-based particles such as y-Fe ₂ O ₃ , Fe ₃ O ₄ , and cobalt-coated y-Fe ₂ O ₃ , ferromagnetic chromium dioxide-based particles, Fe, Co, and Ni. Ferromagnetic metal particles made of these metals and alloys containing these, hexagonal plate-shaped hexagonal ferrite fine particles, and the like can be used.

  In addition, as a binder, polymers such as urethane, vinyl chloride, vinyl acetate, vinyl alcohol, vinylidene chloride, acrylic ester, styrene, butadiene, acrylonitrile, a copolymer combining two or more of these, polyester Resins, epoxy resins, and the like can be used.

  As the organic solvent, ethers, esters, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, chlorinated hydrocarbons, and the like can be used.

(Winding process)
Next, the winding process will be described with reference to FIG. FIG. 1 is a side view schematically showing a winding process line in the magnetic tape processing method according to the present embodiment, and FIG. 2 shows a pancake produced by the magnetic tape processing method according to the present embodiment. It is sectional drawing. 3 is an enlarged cross-sectional view of a main part of a tape reel in which a magnetic tape is wound around a reel hub, where (a) is a cross-sectional view showing a good winding form, and (b) is a cross-sectional view showing a distorted winding form. It is.
In the present embodiment, the winding process is assumed to be a process in which the web WB, which is the above-described original magnetic tape, is cut into a plurality of magnetic tapes MT and wound on the hub 11 to produce the pancake 1. However, the winding process of this invention is not limited to this, For example, it can also apply to the process of winding back the cut ball (pancake) of the cut tape.

  As shown in FIG. 1, the winding process line includes a feeding reel 2 around which a web WB is wound, a cutting device 3 that cuts the web WB into a predetermined width, and produces a plurality of magnetic tapes MT, and a magnetic For example, it mainly includes a winding device 4 that winds the tape MT around the hub 11 and is arranged in, for example, three stages. In addition, a guide roller 5 that guides the web WB from the feed reel 2 to the cutting device 3, and a single ground A suction drum 6 and a tension roller 7 disposed corresponding to the winding device 4 are provided.

  The hub 11 used in the winding process line is made of, for example, a metal such as aluminum, an AS resin, a phenol resin, or an epoxy resin, and 10 to 40% glass fiber is used for these materials. It is preferable to add and strengthen. As shown in FIG. 2, the hub 11 has a diameter reduced from one end side 11a (diameter L1) to the other end side 11b (diameter L2), in other words, a winding surface 11c formed in a tapered shape. Is used. By winding the magnetic tape MT on the winding surface 11c, a curved shape is imparted to the magnetic tape MT. Incidentally, the radius ratio between the one end side 11a and the other end side 11b of the hub 11 is as follows with respect to the bending amount D / L (see FIG. 4) to be applied when the hub width is 18 mm. When changing the hub width, the ratio is calculated accordingly.

  Further, the hub 11 is used in which the diameter L1 of the one end side 11a is 0.5 times or more (L1 ≧ L3 × 0.5) with respect to the diameter L3 of the outer periphery of the pancake 1 to be produced. As a result, the number of windings of the magnetic tape MT around the hub 11 can be suppressed more than in the past. Therefore, the outer peripheral side of the pancake 1 also easily reflects the shape of the hub 11, and a stable curved shape is given to the outer peripheral side of the pancake 1. Incidentally, in the conventional winding process, a hub having a diameter of 11.4 cm (0.3 times the pancake diameter) was used for a pancake having a diameter of 36.0 cm. The curved shape applied to the outer peripheral side was likely to be unstable.

  In the winding process line shown in FIG. 1 configured as described above, the web WB wound around the delivery reel 2 is guided by the guide roller 5 while passing through the cutting device 3 so as to pass a plurality of magnets. Cut to tape MT. Then, the winding roller 4 is continuously wound around each hub 11 while adjusting the winding tension for winding the magnetic tape MT around the hub 11 with the tension roller 7 so as to be 0.8 N / cm or more. It has become. By adjusting the winding tension in this way, the amount of change in the tape width is reduced. This will be clarified in Examples described later. Thus, the pancake 1 in which the magnetic tape MT is wound around the hub 11 is produced.

(Heat treatment process)
The heat treatment step is a step of attaching a curl to ensure a good winding shape by heat-treating the pancake 1 for a predetermined time at a predetermined environmental temperature. In this step, the pancake 1 is heat-treated under conditions that satisfy the following mathematical formula.
t ≧ kT ^-5
However, t: time (H), k: coefficient, T: treatment temperature (° C.).

Here, the coefficient k is a proportionality constant determined by the support of the magnetic tape MT (magnetic tape original fabric). For example, polyethylene terephthalate (PET) is used as the support of the magnetic tape MT (magnetic tape original fabric). In this case, k = 10 ¹⁰ , and preferably k = 2 × 10 ¹⁰ , a practically sufficient bending effect can be obtained. This will be clarified in Examples described later. The processing temperature T is a temperature not higher than the glass transition temperature of the support of the magnetic tape MT.

  When the pancake 1 shown in FIG. 2 is conventionally heat-treated, the stress in the longitudinal direction of the magnetic tape decreases in the vicinity of the middle circumference MT2 as the distance (L3-L1) from the inner circumference MT1 side to the outer circumference MT3 side increases. It is known that it becomes easy to shift. However, in the present embodiment, since the number of windings of the magnetic tape MT is suppressed using the hub 11 having a large diameter, the interval is narrowed. Therefore, the stress applied to the middle circumference MT2 is difficult to decrease, and the pancake 1 is hardly displaced. Further, since the number of windings of the magnetic tape MT is suppressed, the tightening stress applied to the inner peripheral MT1 side by the heat treatment is small, and the change amount (spreading deformation) of the tape width caused by the inner peripheral MT1 side being crushed is reduced. It can be suppressed.

  Thus, by producing the pancake 1 in which the number of windings of the magnetic tape MT is suppressed, it is possible to attach a curl that gives a stable curved shape to the magnetic tape MT. Thereafter, the magnetic tape MT is wound and shipped by a predetermined amount on the reel hub 81 of the flanged tape reel 8 shown in FIG. 3. At this time, in this embodiment, a stable curved shape is given to the magnetic tape MT. Therefore, it is possible to secure a good winding shape in which the positions of the end surfaces of the edge ed of the magnetic tape MT are aligned as shown in FIG. On the other hand, according to the pancake in which a certain curved shape cannot be obtained, a distorted winding shape in which the positions of the edges ed of the magnetic tape MT are not uniform as shown in FIG.

  Further, in the present embodiment, since the number of windings of the magnetic tape MT is suppressed with respect to the hub 11 shown in FIG. 2, a shift in the vicinity of the middle circumference caused by heat-treating the pancake 1 is difficult to occur. As a result, it is possible to prevent damage caused by rubbing (shifting) the magnetic tape MT. Furthermore, the amount of change in the tape width on the inner circumference MT1 side of the pancake 1 caused by the heat treatment can be reduced. As a result, it is possible to prevent damage to the edge ed (see FIG. 3) that occurs when the edge ed of the magnetic tape MT protrudes unevenly.

  Although the present embodiment has been described above, the present invention is not limited to the above-described embodiment, and can be implemented with appropriate modifications within the scope of the technical idea of the present invention.

  In order to improve productivity in the process, it is required to wind the magnetic tape MT long by one hub 11. However, when the winding length is increased, the amount of bending applied to the outer periphery is decreased, the tape width change amount on the inner peripheral MT1 side is increased due to the increase of the tightening stress, and the stress is decreased in the vicinity of the intermediate peripheral MT2. There is a concern that the magnetic tape MT may be displaced after the heat treatment. In order to solve these problems, the following examination was performed in this example to confirm the effect of the present invention.

(Examination of hub diameter)
Quality evaluation results when heat treatment was performed by winding a magnetic tape having a total thickness of 9 μm and a length of 4000 m around a NAB standard hub having a diameter of 114 mm (taper amount of 30 μm), 150 mm (taper amount of 40 μm), and 250 mm (taper amount of 70 μm). Compared. The results are shown in Table 2. A hub having a taper amount capable of obtaining a bending amount of 2 mm / m from Table 1 was prepared. The taper amount is a difference in radius between the one end side and the other end side (length L4 shown in FIG. 2).

ここで、幅変化量とは、テープの幅方向におけるプラスの変化量をいう。

Here, the width change amount means a positive change amount in the tape width direction.

  According to Table 2, in Comparative Example 1 (when a hub having a diameter of 114 mm is used), the inner peripheral curve amount is 1.7 mm / m, while the outer peripheral curve amount is 0.2 mm / m. There was a difference in the amount of bending on the outer peripheral side. That is, it was impossible to give a certain curvature. Further, a tape deviation occurred, and the width change amount was as large as 6 μm. On the other hand, in Example 1 (when a hub having a diameter of 150 mm was used), the amount of inner periphery was 1.6 mm / m, and the amount of outer periphery was 0.8 mm / m. Further, no tape deviation occurred, and the width change amount was halved compared to Comparative Example 1. In Example 2 (when a hub having a diameter of 250 mm was used), the amount of inner periphery was 1.8 mm / m, and the amount of outer periphery was 1.2 mm / m. Further, no tape deviation occurred, and the amount of change in width was one-third that of Comparative Example 1.

  According to this, it was found that the hub diameter was 0.5 times or more, preferably 0.6 times or more the pancake diameter, and good results were obtained. However, due to space limitations of the winding device in the process, it is considered that the pancake diameter is desirably 600 mm or less. For example, assuming that a magnetic tape having a thickness of about 9 μm is wound up to 10,000 m, the diameter of the hub is maximum. It is desirable that it is 500 mm. Although the effect is reduced when the hub diameter is small, the results of the experiment show that the hub of Example 1 with a diameter of 150 mm has a practically sufficient effect (outer peripheral side bending amount, no tape displacement, reduced width change amount). Was found to be obtained.

(Verification of bending amount)
In order to give a desired curved shape to the magnetic tape MT, a taper amount (radius difference between one end side and the other end side, a length L4 shown in FIG. 2) corresponding to the hub diameter is required. This is determined (calculated) as follows according to the diameter of the hub and the desired amount of bending.

  On the other hand, the amount of bending of the magnetic tape was measured by winding the magnetic tape on a hub having a taper winding surface and heat-treating it in an environment of a temperature of 60 ° C. and a humidity of 25% for 32 hours. The results are shown in Table 6. In addition, the result shown in Table 6 measured 5 times and showed the average value.

  In Example 3, in order to obtain a bending amount of 0.5 mm / m with a hub having a diameter of 150 mm, the bending amount was measured with the taper amount of the hub being 10 μm (see Table 3). On the other hand, the obtained amount of bending was 0.53 mm / m, and it was found that a desired amount of bending was obtained. Further, in other Examples 4 to 6, it was found that almost the desired amount of bending was obtained in the same manner as in Tables 3 to 5.

(Examination of winding tension)
Table 7 shows the quality evaluation results when using a hub (no taper) with a diameter of 250 mm and winding a 4000 m magnetic tape while changing the winding tension. The winding speed is 10 m / s.

  According to Table 7, there was no great difference in the amount of bending in each example. However, in Comparative Example 2, when the winding tension was 80 gf / 0.5 inch (≈0.6 N / cm), the tape was displaced and the width change amount was 2 μm. On the other hand, in Example 7, when the winding tension is 100 gf / 0.5 inch (≈0.8 N / cm), the deviation of the tape is eliminated and the width change amount is 1 μm, which is half that of Comparative Example 2. A good result was obtained. Furthermore, in Example 8, when the winding tension was set to 120 gf / 0.5 inch (≈0.9 N / cm), good results were obtained as in Example 7.

  According to this, it has been found that winding with a winding tension of 0.8 N / cm or more is effective in preventing tape displacement and reducing the change in tape width. Increasing the tension is thought to increase the tightening stress and increase the amount of change in width, but if pulled, it is thought that the contribution of the effect of narrowing the tape width due to material balance is significant.

(Examination of heat treatment time)
In order to confirm the temperature and time at which the relaxation phenomenon due to the heat treatment is almost saturated, the temperature and time conditions and the amount of bending were examined under the condition that the bending is given, and the results are shown in Table 8. As the pancake to be heat-treated, a support made of polyethylene terephthalate (PET) and wound around a hub having a diameter of 200 mm with a winding tension of 100 gf / 0.5 inch was used.

According to Table 8, the relationship between the temperature T at which the relaxation phenomenon is almost saturated and the time t is
It was found that it can be expressed by the equation “t≈2 × 10 × T ⁻⁵ ”.

  On the other hand, in an actual heat treatment process, it is effective to select conditions that achieve both productivity and effects. Therefore, the amount of bending during the heat treatment time that is half the saturation time was examined. The results are shown in Table 9.

According to Table 9, it was found that a sufficient amount of bending can be obtained even with a heat treatment time that is half the saturation time. From this result, the relationship between the temperature T and the time t in the heat treatment step is
It was found that it can be expressed by the formula “t ≧ 10 ¹⁰ × T ⁻⁵ ”. Since the coefficient of T ^-5 varies depending on the conditions of the support, etc., the relationship between the temperature T and the time t during the heat treatment should satisfy the equation “t ≧ k × T ^-5 ”. That's fine. Incidentally, the humidity is desirably controlled within the range of 20 to 80% relative to the above heat treatment conditions in order to prevent tape displacement after heat treatment and to reduce and increase the amount of change in width.

It is a side view which shows typically the line of the winding process in the processing method of the magnetic tape which concerns on this embodiment. It is sectional drawing of the pancake produced with the processing method of the magnetic tape which concerns on this embodiment. It is a principal part expanded sectional view of the tape reel by which the magnetic tape was wound by the reel hub, (a) is sectional drawing which shows a favorable winding form, (b) is sectional drawing which shows the disorder | damaging winding form. It is a top view of the magnetic tape which has a curved shape.

Explanation of symbols

1 pancake 11 hub 11a one end side 11b other end side 11c winding surface MT magnetic tape MT1 inner circumference MT2 middle circumference MT3 outer circumference WB web

Claims (3)

A tape is wound around a hub having a taper-shaped winding surface to produce a wound ball, and the wound ball is heat-treated.
A tape processing method characterized by using a hub having a diameter of 0.5 times or more of the diameter of the outer periphery of the wound ball at the time of producing the wound ball.   2. The tape processing method according to claim 1, wherein a winding tension for winding the tape around the hub is set to 0.8 N / cm or more when the wound ball is manufactured. The said wound ball is heat-processed on the conditions which satisfy | fill the following numerical formula, The processing method of the tape of Claim 1 or Claim 2 characterized by the above-mentioned.
t ≧ kT ^-5
However, t: time (H), k: coefficient, T: treatment temperature (° C.).

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