JPH0469813A - Tape-shaped recording medium and production thereof - Google Patents

Abstract

PURPOSE:To prevent the generation of drop-outs and to improve a high-speed traveling property by using a base film which is larger in the modulus of elasticity in the modulus of elasticity in a transverse direction orthogonal with the longitudinal direction of the tape than the modulus of elasticity in the longitudinal direction. CONSTITUTION:The magnetic tape 6 is formed by forming a magnetic layer on the surface of the base film. A nonmagnetic plastic film is used for the base film. The ratio of the modulus of elasticity in the transverse direction (ETD) to the modulus of elasticity in the longitudinal direction (EMD) thereof is specified to >=1.1. The A broad raw sheet formed by depositing and forming a magnetic layer on the base film in such a manner and subjecting the layer to a mirror treatment is cut to a prescribed width to form the magnetic tape 6. An extremely sharp cut end is obtd. in this way and the dislodgment of a part of the recording layer from the cut end is obviated. Therefore, the dropouts are decreased and the traveling condition of the tape is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tape-shaped recording medium used in, for example, a magnetic tape cartridge for a VTR, and a method for manufacturing the same, and particularly relates to a base film thereof and a method for manufacturing the same. The present invention relates to a method for slitting the original fabric formed by the method.

[Prior Art] A magnetic tape used in a magnetic tape cartridge or the like is made by coating a base film of a wide plastic film made of polyethylene terephthalate or the like with a magnetic layer having a predetermined thickness by an appropriate method such as coating or vapor deposition. It is formed into a raw fabric. Then, this original fabric is slittered to obtain a magnetic tape having a large number of predetermined paddles, and this magnetic tape is assembled into a cartridge case to assemble a magnetic tape cartridge.

[Problem to be solved by the invention] By the way, in conventional magnetic tapes, especially magnetic tapes for VTRs, dropouts increase due to repeated use.
There is also the problem that running performance deteriorates.

As a result of various studies on these issues, the inventors found that
It has been found that the condition of the cut end of the magnetic tape during slitting has a large effect on the occurrence of the aforementioned dropouts and on the quality of running performance.

That is, the base film made of polyethylene terephthalate used in conventional magnetic tapes has an elastic modulus (EMD) of 700 kg/m in the longitudinal direction of the magnetic tape.
The elastic modulus in the width direction (ETD) perpendicular to the longitudinal direction is about 500 Kg/mm, and the elastic modulus in the width direction (ETD) is about 500 Kg/mm.
) ratio (ETD) / (EMD) is 1/1.4 = 0
．． 7, and the elastic modulus in the longitudinal direction (EMD) is larger than the elastic modulus in the transverse direction (ETD).

On the other hand, a slitter that produces magnetic tape with a predetermined width from a raw material has a rotating upper blade and a rotating lower blade that rotate almost synchronously, and the raw material is passed between both blades and is sheared to a predetermined width. It is designed to be cut to the width of . At this time, as mentioned above, if a base film is used whose elastic modulus in the longitudinal direction (EMD) is larger than the elastic modulus in the transverse direction (ETD), stress will be difficult to concentrate during shearing, and this will cause sagging and sagging. This may cause the cut surface to become uneven.

If the cut edge of the magnetic tape is in poor condition, magnetic powder may fall off from the edge of the cut edge, causing dropouts, and the running condition at high speeds may deteriorate, causing problems in terms of operational reliability. There is.

The purpose of the present invention is to eliminate such drawbacks of the prior art,
An object of the present invention is to provide a tape-shaped recording medium with excellent performance and high reliability, and a method for manufacturing the same.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a magnetic tape, for example, in which a recording layer such as a magnetic layer is formed on a base film made of a non-magnetic material such as polyethylene terephthalate. The target is tape-shaped recording media.

The elastic modulus (EMD) of the base film in the width direction perpendicular to the tape-like longitudinal direction (EMD)
ETD) is larger [(EMD) < (ETD
) ].

In order to achieve the above-mentioned object, the present invention further provides a tape-like recording medium by cutting a wide tape-like recording medium material having a recording layer formed on a base film made of a non-magnetic material into a predetermined width by passing it through a slitter. The present invention is directed to a method for producing a tape-shaped recording medium.

The elastic modulus (EMD) of the base film in the width direction perpendicular to the tape-like longitudinal direction (EMD)
ETD) is larger [(EMD) < (ETD)
(e) The slitter has two blade bodies facing each other, and is provided with a pressing member such as rubber for pressing the raw fabric against one of the blade bodies, and the pressing member pushes the raw fabric against one blade body in an elastic manner. It is characterized by cutting with two opposing blades while pressing against the target.

In order to achieve the above-mentioned object, the present invention further provides a tape-like recording medium by cutting a wide tape-like recording medium material having a recording layer formed on a base film made of a non-magnetic material into a predetermined width by passing it through a slitter. The present invention is directed to a method for producing a tape-shaped recording medium.

The elastic modulus (EMD) of the base film in the width direction perpendicular to the tape-like longitudinal direction (EMD)
ETD) is larger [(EMD)<(E D)
For example, 0.0 mm per inch width in the slit direction of the original fabric.
It is characterized by cutting with a tension of 2 Kgf or more applied.

In order to achieve the above-mentioned object, the present invention further provides a tape-like recording medium by cutting a wide tape-like recording medium material having a recording layer formed on a base film made of a non-magnetic material into a predetermined width by passing it through a slitter. The present invention is directed to a method for producing a tape-shaped recording medium.

The elastic modulus (EMD) of the base film in the width direction perpendicular to the tape-like longitudinal direction (EMD)
E TD) is larger and [(EMI)) < (ETD
) ], the slitter has two blade bodies facing each other, a pressing member for pressing the raw fabric against one of the blade bodies is provided, the pressing member presses the raw fabric against one of the blade bodies, and the slit is This method is characterized in that the original fabric is cut with the two opposing blades while applying tension in the direction.

[Operations] As described above, the present invention has a longitudinal elastic modulus (
The elastic modulus in the width direction perpendicular to it (ET
D) is larger [(EMD) <(ETD) ]
By using a base film, when the original fabric is cut into a predetermined width using a slitter, stress is concentrated on the sheared portion, resulting in sharp cuts. Therefore, it is possible to obtain a highly reliable tape-shaped recording medium that eliminates the occurrence of dropouts and has very good running performance at high speeds.

In addition, by cutting the raw material while elastically pressing it against one of the blades with a pressing member, in combination with increasing the elastic modulus in the width direction of the base film mentioned above, a clean cut is formed. can do.

[Example] Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a V using a magnetic tape according to an embodiment of the present invention.
A perspective view of the magnetic tape cartridge for TR with the rotary lid open; FIG. 2 is a schematic side view of the slitter used to cut the original magnetic tape; and FIG. 3 is a schematic side view of the slitter when cutting the original magnetic tape. 4 is an enlarged sectional view of a magnetic tape (one roll), FIGS. 5 and 6 are sectional views of a slitter, and FIG. 7 is a diagram for explaining cutting of an original tape.

As shown in FIG. 1, a magnetic tape cartridge for a VTR includes a cartridge case 1 consisting of an upper case 2 and a lower case 3, a rotating lid 4 rotatably attached to the front surface of the cartridge case 1, and The cartridge case 1 is wound around two reels (not shown) inside the cartridge case 1, and the negative part of the reel is guided by a guide part 5 formed on the front surface of the cartridge case 1.
The magnetic tape 6 and the like are exposed on the front surface of the magnetic tape 6.

In the case of a magnetic tape cartridge for a VTR, when it is installed in a recording/reproducing device, the rotary lid 4 opens automatically as shown in the figure, and a portion of the magnetic tape 6 is inserted into the cartridge case 1. It is pulled out from the front, loaded onto a rotating sling with a magnetic head, and runs at high speed.

The magnetic tape 6 is composed of a base film 7 and a magnetic layer 8 formed on the surface thereof, as shown in FIG.

As the base film 7, a non-magnetic plastic film such as polyethylene terephthalate, polyimide, or polysulfone is used. The thickness of this base film 7 is about 6 to 30 μm, and in the fifth embodiment, it is 14.5 μm. The longitudinal direction of the magnetic tape of this base film 7, that is, the direction of the slit (third
The elastic modulus (EMD) in the X direction in the figure is 500 Kg/mm2
The elastic modulus (ETD) in the width direction (Y direction in Figure 3) perpendicular to the longitudinal direction is 700 Kg/mmz, and the elastic modulus in the width direction (ETD) with respect to the elastic modulus in the longitudinal direction (EMD) The ratio of (ETD) / (EMD) is 1°4/
1=1.4, and contrary to the conventional case, the elastic modulus in the transverse direction (ETD) is larger than the elastic modulus in the longitudinal direction (EMD) (EMD<ETD).

Examples of the composition of the magnetic layer 8 are as follows.

Composition of magnetic layer Co-adhered - Fe, 02 magnetic powder 100 parts by weight Nitrocellulose 10 parts by weight Polyurethane resin 9M parts Polyisocyanate
1 part by weight granular α-Fe, O, powder
5 parts by weight carbon black 5
Part by weight Zinc stearate 0.5 part by weight -〇-Butyl stearate 0.5 part by weight The thickness of the magnetic layer 8 is about 3 to 8 μm, and in this example, the thickness is about 5 μm.
It is μm.

The magnetic layer 8 is coated and formed on the base film 7 in this way, and the mirror-treated wide original film 9 is wound up into a roll as shown in FIG. In the slitting process, the raw fabric 9 is sequentially pulled out from this roll and passed through a slitter 10. As shown in the figure, this slitter 10 has an upper rotating blade 11 and a lower rotating blade 12 facing each other so as to mesh with each other. When the circumferential speed of the double-edged blade 11.12 is vX and the feed speed of the web 9 is 2, the circumferential speed of the blade 11.12 is slightly higher than the feed speed v2 of the web 9 (for example, 1~ 5%) faster (■, >V2). By passing the raw material 9 unwound from the roll between the two blades 11 and 12, the raw material 9 is cut into a predetermined width to form the magnetic tape 6, as shown in FIG.

5 and 6 are diagrams for explaining the structure of the slitter 10. FIG. The rotating upper blade body 11 has an upper rotating #
113, a large number of upper blade holders 14 attached to the outer peripheral surface of the upper rotating shaft unit 3, and upper blades 16 fixed to each of the upper blade holders 14 via disc springs 15.

On the other hand, the rotating lower blade body 12 includes a lower rotating shaft 17 and a number of lower blades 18 attached to the outer peripheral surface of the lower rotating shaft 17. A recess 19 is formed in the lower blade 18 at a position facing the upper blade 16. Therefore, the interval between the upper blades 16 is the same as the tape radius.

In the case of the slitter 10 shown in FIG. 6, the upper blade holder 14
An elastic holding member 2o made of rubber or the like is attached to the lower surface of the holding member 2o. Although rubber is used as the elastic presser member 20 in this embodiment, it is also possible to use a highly elastic thin metal plate or felt.

By inserting the raw fabric 9 unwound from the roll between the rotating upper blade body 11 and the rotating lower blade body 12, as shown in FIGS. 5, 6, and 7, double blade bodies 11.12 As the upper blade 16 rotates, the upper blade 16 lowers relative to the lower blade 18, and at first a small crack 21 occurs (see Fig. 7). As it increases, the crack 21 runs straight on the line connecting the tips of the dispensing blade 16 and the lower blade 18 without branching, resulting in a clean cut without any droop or sagging.

FIG. 8 and FIG. 9 are principal stress distribution diagrams during cutting of the original fabric. FIG. 8 shows a conventionally used base film of polyethylene terephthalate rings (thickness: 14 mm).
5 μm), and the longitudinal elastic modulus (EMD) of the tape is 7.
00Kg/mm”, elastic modulus in the width direction (ETD) is 50
0Kg/mm”, N person ratio (ETD) / (EM
D) is a principal stress distribution diagram when using a sample (sample A) of 0.7. In the 9th article, the same base film (thickness 14.5 μm) is made of polyethylene terephthalate rings, but it is related to Example 5 of the present invention, and the elastic modulus (EMD) in the longitudinal direction of the tape is 500 Kg/mm. This is a principal stress distribution diagram when a sample (sample B) in which the elastic modulus (ETD) in 11 directions is 700 Kg/mm'' + the ratio (ETD)/(EMD) of 1.4 is used.

Furthermore, FIGS. 10 and 11 are equivalent stress distribution diagrams during cutting of the original fabric. FIG. 10 shows the sample A.
(Conventional product), Fig. 11 shows the sample B (conventional product).
FIG. 3 is a stress distribution diagram when using the product of the present invention.

This principal stress distribution and equivalent stress distribution are obtained by determining the distribution of stress generated within the base film using the finite element method.

In FIGS. 8 and 9, the dotted line indicates the direction of the minimum principal stress.1 Both principal stress distributions are similar, and compressive stress is distributed at the contact interface between the sample and the blade.

It can be seen that tensile stress is concentrated near the cutting edge, which is a location where initial cracks are likely to occur.

As is clear from the equivalent stress distributions in Figures 10 and 11, stress concentration is seen near the cutting edge, but the degree of concentration is greater in sample B, which has a higher modulus of elasticity in the width direction, than in sample A. It can be verified that this is the sample that yields most easily and that cracks tend to grow straight, in other words, it is a sample with a clean cut.

[Effect of the invention] Next, a performance comparison will be made between a specific example of the present invention and a conventional one.
．． A 5 μm thick polyethylene terephthalate film was used, and a 5 μm thick magnetic layer was formed thereon. In addition, EMD in the table is the elastic modulus in the longitudinal direction of the tape, ET
D is the elastic modulus of the tape in the width direction, slitter X uses the slitter having the structure shown in FIG. 5, and slitter Y shows the tape cut using the slitter having the structure shown in FIG. Furthermore, the tension indicates the tension per inch width when pulled in the slit direction during H-cutting.

Table 1 was measured.

Table 2 A magnetic tape cartridge for a VTR was assembled using each of the magnetic tapes shown in Table 1, and a dropout test was conducted on each tape cartridge.The results are summarized in Table 2 below. In the test, the recorded normal signal was used as the OdB reference level, and a dropout was defined as a dropout in which the playback output decreased to 120dB and continued for 15μ seconds.As is clear from Table 2, the number of dropouts that occurred was In addition, the embodiments of the present invention use a base film whose elastic modulus in the width direction (ET) is larger than the elastic modulus (EMD) in the tape-like longitudinal direction. This high modulus of elasticity in the width direction prevents sagging or sagging when slitting, and the strong elasticity makes it easy to concentrate stress, so the cut ends are very sharp without zigzag, making it easy to record. As a result, no part of the layer falls off from the cut.

As a recording medium, it has excellent performance with few dropouts, and the tape runs in good condition.

Also, the ratio of the elastic modulus in the width direction (ETI) to the elastic modulus in the longitudinal direction (E ND) of the tape (ETD) / (EM
D> is calculated as shown in Table 3 below.

Table 3 As is clear from comparing this Table 3 and the above Table 2, the base film of the present invention has (ETD)/(EMD)
is 1.1 or more, especially 1.4 (Examples 1, 3, 4)
．． 6) Since there is a large difference between the elastic modulus of the tape in the length direction and the width direction, dropouts are less likely to occur. This means that when tension is applied in the length direction, the shrinkage in the width direction is small, and the break occurs with relatively little deformation when the upper blade enters, resulting in a good cut and no dropouts. You can predict when it gets low.

Also, one using slitter Y (Example 4゜5.6)
When slitting, most of the material is pressed against the lower blade side and cut with little elongation, resulting in very clean cuts and fewer dropouts.

As mentioned above, the present invention has a tape-like longitudinal elastic modulus (
EMD), the elastic modulus in the width direction perpendicular to it (E
TD) is larger [ (EMD) ((ETD)
By using a base film, when the original fabric is cut into a predetermined width using a slitter, stress is concentrated on the sheared portion, resulting in sharp cuts. This eliminates the occurrence of dropouts and provides very good running performance at high speeds.

A highly reliable tape-shaped recording medium can be obtained.

In addition, by cutting the original fabric while elastically pressing it against one of the blades using a pressing member, in combination with increasing the elastic modulus of the base film in the width direction described above, a clean cut can be formed. This reduces dropouts and improves running performance.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a magnetic tape cartridge for a VTR using a magnetic tape according to an embodiment of the present invention, with the rotary lid open; FIG. FIG. 3 is a schematic side view of the slitter. FIG. 3 is a plan view of the original fabric at the time of cutting, FIG. 4 is an enlarged sectional view of the magnetic tape (original fabric), FIGS. 5 and 6 are sectional views of the slitter, and FIG. Figures 8 and 9 are principal stress distribution diagrams during cutting of the original fabric, and Figures 10 and 11 are diagrams for explaining the cutting of the original fabric. It is an equivalent stress distribution diagram at the time of non-cutting. 6... Magnetic tape, 7... Base film, 8... Magnetic layer, 9... Original fabric, 1
0... Slitter, 11... Rotating upper blade body, 12... Rotating lower blade body, 20... Elastic presser member, X...・Longitudinal direction of tape, Y...
...The width direction of the tape. Figure 3 Figure 2 Figure 2 Figure Figure 10 Figure 11 Procedural amendment form) Specification October 1990

Claims (8)

[Claims] (1) In a tape-shaped recording medium in which a recording layer is formed on a base film made of a non-magnetic material, the base film has an elastic modulus in the longitudinal direction of the tape (
The elastic modulus in the width direction (ETD) perpendicular to EMD)
) is larger [(EMD)<(ETD)]. (2) In claim (1), the elastic modulus in the width direction (ET) with respect to the elastic modulus in the longitudinal direction (EMD) of the tape
A tape-shaped recording medium characterized in that the ratio (EMD)/(ETD) of D) is 1.1 or more. (3) A method for manufacturing a tape-shaped recording medium in which a wide tape-shaped recording medium material in which a recording layer is formed on a base film made of a non-magnetic material is passed through a slitter and cut into a predetermined width to obtain a tape-shaped recording medium. , the base film has a tape-like longitudinal elastic modulus (
The elastic modulus in the width direction (ETD) perpendicular to EMD)
) is larger [(EMD)<(ETD)], and the slitter has two blade bodies facing each other, and is provided with a pressing member that presses the raw fabric against one of the blade bodies, A method for manufacturing a tape-shaped recording medium, which comprises cutting the tape-shaped recording medium with two opposing blade bodies while pressing the tape-shaped recording medium against one blade body with the pressing member. (4) In claim (3), the elastic modulus in the width direction (ET) with respect to the elastic modulus in the longitudinal direction (EMD) of the tape
A method for producing a tape-shaped recording medium, characterized in that the ratio (ETD)/(EHD) of D) is 1.1 or more. (5) A method for manufacturing a tape-shaped recording medium, in which a wide tape-shaped recording medium in which a recording layer is formed on a base film made of a non-magnetic material is passed through a slitter and cut into a predetermined width to obtain a tape-shaped recording medium. and the base film is
The elastic modulus (ETD) in the width direction perpendicular to the longitudinal direction (EMD) of the tape is larger than the elastic modulus (EMD) in the longitudinal direction [(E
MD)<(ETD)], A method for producing a tape-shaped recording medium, characterized by cutting the original fabric while applying tension in the slit direction. (6) In claim (5), the elastic modulus in the width direction (ET) with respect to the elastic modulus in the longitudinal direction (EMD) of the tape
A method for manufacturing a tape-shaped recording medium, characterized in that the ratio (ETD)/(EMD) of D) is 1.1 or more. (7) A method for manufacturing a tape-shaped recording medium in which a wide tape-shaped recording medium material in which a recording layer is formed on a base film made of a non-magnetic material is passed through a slitter and cut into a predetermined width to obtain a tape-shaped recording medium. and the base film is
The elastic modulus (ETD) in the width direction perpendicular to the longitudinal direction (EMD) of the tape is larger than the elastic modulus (EMD) in the longitudinal direction [(E
MD) < (ETD)], the slitter has two blade bodies facing each other, and is provided with a pressing member that presses the raw fabric against one of the blade bodies, and presses the raw fabric against one of the blade bodies with the pressing member. A method for manufacturing a tape-shaped recording medium, characterized in that the original fabric is cut by the two opposing blades while pressing the tape against the blade and applying tension in the slit direction. (8) In claim (7), the elastic modulus in the width direction (ET) with respect to the elastic modulus in the longitudinal direction (EMD) of the tape
A method for manufacturing a tape-shaped recording medium, characterized in that the ratio (ETD)/(EMD) of D) is 1.1 or more.