JPH10199192A - Magnetic recording tape cassette - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of a drop-out characteristic by the change in properties of a magnetic tape at a practicable use level, to assure the durability of this magnetic tape and to assure the smooth traveling property of the magnetic tape by incorporating a specific ratio of phthalate into the resin lid parts of a magnetic recording tape cassette. SOLUTION: The content of the phthalate incorporated into the resin lid part of the magnetic recording tape cassette is specified to 1 to 20ppm. As a result, all of the still characteristics of the magnetic tape before and after preservation under a high-temp. and high-humidity environment exhibits good values of >=120 minutes. The increase rate of the drop-out is suppressed to a relatively low value of 10 to 100%. If the content of the phthalate exceeds 20ppm, the still characteristics are drastically deteriorated and the increase rate of the drop-out attains an extremely high value. The electric resistance becomes lower as the content of the phthalate incorporated into the lid part of the magnetic tape cassette is higher.

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 comprising a metal thin film type magnetic recording medium, and in particular, a short-wavelength magnetic recording signal (high-density magnetic recording) such as a high-band 8 mm video tape or a digital VTR. The present invention relates to a magnetic recording tape cassette made of a magnetic recording medium suitable for recording and reproducing data.

[0002]

2. Description of the Related Art Magnetic tapes having a ferromagnetic metal thin film in a magnetic layer have better characteristics in terms of recording density and the like than, for example, coating type magnetic recording tapes. It has been put to practical use as a recording tape.

[0003] Also, considering the development of the magnetic tape field in the future, application fields such as digital video recorders and other high-quality video recorders and digital tape recorders are expected to be widely used. I have.

FIGS. 1 and 2 show a perspective view and a schematic exploded view of a magnetic recording tape cassette, respectively. The magnetic recording tape cassette 100 includes an upper shell 101 and a lower shell 102 that house a pair of reels 200 around which a magnetic tape 120 is wound. In addition, a lid portion 103, in this example, a front lid 103a and a back lid 1 are provided in front of the shells 101 and 102.
03b is arranged so that opening and closing are possible.

The reel 200 has an upper flange 201,
It has a lower flange 202 and a hub 203 around which a magnetic tape 120 is wound, at the center between them.

In the magnetic recording tape cassette 100, a magnetic tape 120 is sandwiched between a front lid 103a and a back lid 103b of a lid 103 at a front portion thereof. Therefore, the magnetic tape 120 is disposed at a position close to both the lids 103a and 103b of the lid portion 103.

[0007]

By the way, the lid portion 103 of the magnetic recording tape cassette 100 contains a phthalate ester as a plasticizer, so that the charging of the magnetic tape 120 is suppressed in the lid portion 103. This has the effect of being done. In addition, the lid 103
It also has a role of protecting the magnetic tape 120 from dust and the like.

However, when the magnetic characteristics of the magnetic tape 120 are inspected after the magnetic recording tape cassette 100 is stored for a long time in a high-temperature and high-humidity environment, the magnetic tape 12
The characteristics of 0, for example, still characteristics and recording / reproducing characteristics are deteriorated.

This is because the magnetic tape 120
Is located at a position close to the lid portion 103, so that the phthalate ester contained in the lid portion 103 is
It has been found that this is because the properties of the magnetic tape 120 are adversely affected.

Accordingly, the present inventor has conducted intensive studies, and as a result, by controlling the amount of phthalate ester contained as a plasticizer in the lid portion 103 of the magnetic recording tape cassette 100 to a specific range, It has been found that the deterioration of the dropout characteristic due to the deterioration of the tape can be suppressed to a practical level, the durability of the magnetic tape can be secured, and the smooth running property of the magnetic tape can be secured.

[0011]

In the magnetic recording tape cassette of the present invention, the lid portion made of resin contains 1 to 20 ppm of a phthalic acid ester.

According to the present invention, the amount of the phthalate ester contained in the lid portion of the magnetic recording tape cassette having the resin-made lid portion is set to 20 ppm or less, so that the phthalate ester adversely affects the magnetic tape. As a result, the deterioration of the dropout characteristics due to the deterioration of the magnetic tape can be suppressed to a practical level, and the durability of the magnetic tape can be ensured.

Further, by setting the amount of the phthalic acid ester contained in the lid portion to 1 ppm or more, the electrification of the magnetic tape can be prevented, and the stable running property of the magnetic tape can be secured.

That is, when a large amount of phthalate ester contained as a plasticizer is present in the lid portion of the magnetic recording tape cassette and the magnetic recording tape cassette is stored in a high-temperature and high-humidity environment, phthalic acid is removed from the lid portion. The ester volatilizes and adheres to the magnetic tape and reacts with the metal of the magnetic layer of the magnetic tape, resulting in deterioration of the magnetic tape, deterioration of dropout characteristics, and deterioration of durability. By reducing the amount of the phthalate ester contained in the lid portion to 20 ppm or less, the adverse effect of the phthalate ester on the magnetic tape is reduced, and the deterioration of the dropout characteristic due to the deterioration of the magnetic tape is suppressed to a practical level. The durability of the tape can be ensured.

In a home digital VTR or the like for recording digital image signals, the recording track pitch is extremely narrow, 10 μm, due to the necessity of high-density magnetic recording. ,
The effects are more likely to appear than before, and thorough improvements are needed.

On the other hand, since the phthalic acid ester in the lid portion of the magnetic recording tape cassette has an antistatic effect of the magnetic tape as described above, if the content of the phthalic acid ester is too small, it will be sufficient. In view of the fact that the antistatic effect of the magnetic tape cannot be obtained and the running property of the magnetic tape may be impaired, when the amount of the phthalate ester contained in the lid portion is 1 ppm or more, the magnetic tape Charging can be prevented, and stable running of the magnetic tape can be ensured.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording tape cassette in which a phthalate ester contained as a plasticizer in a resin lid adheres to a magnetic tape by volatilization and reacts with a metal in a magnetic layer. However, in view of adversely affecting the properties of the magnetic tape and affecting the running properties of the magnetic tape, the present invention provides a magnetic recording tape cassette whose content is controlled to 1 to 20 ppm.

Hereinafter, embodiments of the present invention will be described. The magnetic recording tape cassette of the present invention can be applied to a magnetic recording tape cassette having the same structure as described above, which is shown in a perspective view and an exploded view in FIGS.

That is, as shown in FIGS. 1 and 2,
The magnetic recording tape cassette 100 includes an upper shell 10
1 and a lower shell 102 are accommodated and accommodated with a pair of reels 200 around which a magnetic tape 120 is wound. A lid part 10 is provided at the front part of both shells 101 and 102.
3. In this example, the front lid 103a and the back lid 103b are arranged to be openable and closable.

For the front lid 103a and the back lid 103b, for example, ABS (acrylonitrile styrene butylene) is used, and a phthalate ester is added as a plasticizer. In addition, as the phthalic acid ester, for example, diethyl phthalate can be used, but it is not limited to this example. The higher the molecular weight, the lower the volatility.

The reel 200 has an upper flange 201,
It has a lower flange 202 and a hub 203 around which a magnetic tape 120 is wound, at the center between them.

In the magnetic recording tape cassette 100, at the front part thereof, the magnetic tape 120 is connected to the front lid 103a and the back lid 103a of the lid part 103.
b. Therefore,
The magnetic tape 120 is attached to both lids 10 of the lid portion 103.
It is arranged at a position close to 3a and 103b.

Here, the amount of phthalic acid ester contained as a plasticizer in the resin-made lid portion 103 of the above-mentioned magnetic recording tape cassette 100 is measured, and the magnetic recording tape cassette 100 has a lid portion 103 having a different phthalate ester content. A magnetic recording tape cassette was prepared and used as samples for Examples 1 to 6 and Comparative Examples 1 and 2, respectively.

A method for measuring the amount of phthalic acid ester contained in the lid 103 of the magnetic recording tape cassette 100 will be described below.

First, the front lid 103a and the back lid 103b of the magnetic recording tape cassette are each crushed and weighed to 5 g, which is used as a powder sample. Next, 100 ml of acetone is added to this powder sample, and extraction is performed for about 2 hours. Thereafter, the supernatant is measured with a 50 ml measuring cylinder, and this is used as an extracted measurement sample liquid. Here, the extraction time is not limited to 2 hours as long as it is a time sufficient for the extraction to be saturated.

Next, the amount of the phthalic acid ester in the lid portion 103 is measured by gas chromatography mass spectrometry (GC-MS analysis) of the sample liquid for the extraction measurement. In addition, as a measuring device, for example, JEOL DX-303 can be used.

The measurement was performed as described above.
6] and [Comparative Examples 1 and 2]
The results are shown below (Table 1).

[0028]

[Table 1]

Next, the manufacturing conditions of the magnetic tape are shown in the following (Table 2). Note that the conditions for manufacturing the magnetic tape are common to [Examples 1 to 6] and [Comparative Examples 1 and 2].

[0030]

[Table 2]

Hereinafter, the structure of the vapor deposition device used for forming the magnetic layer of the magnetic tape will be described. As shown in FIG. 3, in this vapor deposition apparatus, a feed roll 3 is placed in a vacuum chamber 1 evacuated from exhaust ports 15 and 16 to a vacuum state.
The take-up roll 4 is provided, and the non-magnetic support 2 travels on the feed roll 3 and the take-up roll 4 sequentially.

A cooling can 5 is provided while the non-magnetic support 2 is running from the feed roll 3 to the take-up roll 4. The cooling can 5 is provided with a cooling device (not shown) to suppress deformation and the like of the non-magnetic support 2 due to a rise in temperature.

The non-magnetic support 2 is sequentially fed from the feed roll 3, passes through the peripheral surface of the cooling can 5, and is wound on the take-up roll 4.
The guide rolls 6 and 7 allow the non-magnetic support 2 to run smoothly.

A crucible 8 is provided in the vacuum chamber 1 below the cooling can 5, and the crucible 8 is filled with a metallic magnetic material 9. On the other hand, an electron gun 10 for heating and evaporating the metallic magnetic material 9 filled in the crucible 8 is attached to the side wall of the vacuum chamber 1. In this electron gun 10, the electron beam B emitted from the
It is arranged at a position where it is irradiated to the metal magnetic material 9 inside. The metal magnetic material 9 evaporated by the irradiation of the electron beam B is deposited on the non-magnetic support 2 to form a magnetic layer.

A shutter 13 is provided between the cooling can 5 and the crucible 8 and in the vicinity of the cooling can 5 so as to cover a predetermined area of the non-magnetic support 2 running on the peripheral surface of the cooling can 5. The metal magnetic material 9 evaporated by the shutter 13 is deposited obliquely on the nonmagnetic support 2 within a predetermined angle range.

Further, at the time of depositing the magnetic layer, oxygen gas is supplied to the surface of the non-magnetic support 2 by an oxygen gas introduction pipe 14 provided through the side wall of the vacuum chamber 1, so that magnetic properties, durability, and the like are improved. The weather resistance is improved.

The thickness of the magnetic layer of the magnetic tape is 200
The surface of this magnetic layer is coated with perfluoropolyether as a lubricant, and finally the magnetic tape 120 of the magnetic recording tape cassette 100 shown in FIGS. 1 and 2 can be obtained.

Examples 1 to 5 were prepared as described above.
For the magnetic recording tape cassettes of [6] and [Comparative Examples 1 and 2], the still characteristic and the dropout increase rate were measured before and after storage in a high-temperature and high-humidity environment, respectively. Here, the storage conditions were a temperature of 45 ° C. and a humidity of 80% for 4 days.

After storage under the above conditions, the dropout increase rate and still characteristics of the magnetic tape near the lid 103 in the magnetic recording tape cassette 100 shown in FIGS. 1 and 2 were measured.

In the dropout, the reproduction output attenuation is -10.
A signal loss of not less than dB and a length of signal loss of not less than 10 μsec was detected, and the rate of increase (%) was determined. The still characteristics were measured by measuring the time (minutes) until the recording signal was degraded by −3 dB from the recording signal in the initial state. Note that a modified EVS-900 manufactured by Sony was used for measurement of dropout and still characteristics. Recording signal is 50% white
Performed using

Examples 1 to 6 and Comparative Examples 1 and 2
Table 3 shows the measurement results of the dropout increase rate and the still characteristics of the sample.

[0042]

[Table 3]

In the above (Table 3), the amount of phthalic acid ester contained in the lid portion of the magnetic recording tape cassette of Examples 1 to 6 is 1 to 20 ppm. The still characteristics of the magnetic tape before and after storage in a high-temperature and high-humidity environment under these conditions are both 120 (minutes) or more, which are good values, indicating that deterioration is extremely small.

Further, it can be seen that the dropout increase rate (%) of [Examples 1 to 6] can be suppressed to a relatively low value of 10 to 100 (%).

On the other hand, in Comparative Example 1, the amount of the phthalic ester contained in the lid portion of the magnetic recording tape cassette exceeded 20 ppm, but in this case, the still characteristics were significantly deteriorated. However, it can be seen that the dropout increase rate is also extremely high.

On the other hand, as can be seen from Table 3, the greater the amount of phthalic ester contained in the lid portion 103 of the magnetic recording tape cassette 100, the greater the electrical resistance (Ω).
It turns out that becomes low. This indicates that the phthalic acid ester has an antistatic effect.

In [Comparative Example 2], the amount of phthalic acid ester contained in the lid portion 103 of the magnetic recording tape cassette 100 is less than 1 ppm. In this case, the lid portion of the magnetic recording tape cassette 100 In this case, the magnetic tape was bitten, that is, jamming occurred, and measurement was impossible. This is because the electrical resistance of the magnetic tape was too large due to the small amount of phthalic acid ester contained in the lid portion of the magnetic recording tape cassette, and a sufficient antistatic effect was not obtained.

As described above, when the amount of the phthalic ester contained in the lid portion 103 of the magnetic recording tape cassette 100 exceeds 20 ppm, the magnetic recording tape cassette is stored for a long time in the high temperature and high humidity environment. Later, it can be seen that the magnetic tape 120 near the lid portion 103 is deteriorated, the dropout characteristics of the magnetic tape are deteriorated, and the durability is also deteriorated.

The magnetic recording tape cassette 100
When the amount of the phthalic acid ester contained in the lid portion 103 is less than 1 ppm, the antistatic effect is not sufficiently obtained, and it is found that the running of the magnetic tape 120 is hindered.

That is, in order to prevent electrification of the magnetic tape 120 and to ensure stable running of the magnetic tape 120, the results of Table 3 show that the magnetic recording tape cassette 1
It can be seen that the amount of the phthalic acid ester contained in the lid portion 103 needs to be 1 to 20 ppm.

In the above-described embodiment, the magnetic recording tape cassette in which the lid portion is made of the resin front lid and the back lid has been described. However, the present invention is limited to the magnetic tape cassette having such a configuration. However, the present invention can be similarly applied to a magnetic recording tape cassette having only a front lid as a lid portion.

In the above example, diethyl phthalate was used as the phthalic acid ester contained in the lid portion. However, the present invention is not limited to this example, and dimethyl phthalate, dibutyl phthalate, Other commercially available phthalic acid esters, such as dioctyl phthalate, can be applied in the same manner to achieve substantially the same effect. In this case, in general, the higher the molecular weight is, the higher the boiling point is, so that the volatility from the lid portion is low.

Means for forming the magnetic layer include a vacuum evaporation method in which a ferromagnetic metal material is heated and evaporated under vacuum to deposit it on a nonmagnetic support, and an ion plating method in which the ferromagnetic metal material is evaporated during discharge. A conventionally known method such as a sputtering method and a sputtering method in which atoms on the target surface are knocked out by argon ions generated by causing glow discharge in an atmosphere containing argon as a main component can be applied.

In the above embodiment, Co was used as the magnetic layer. However, the magnetic layer of the magnetic tape 120 near the lid 103 of the magnetic recording tape cassette 100 of the present invention shown in FIG. The ferromagnetic metals such as Fe and Ni, Co-Ni, C
o-Fe-Ni, Fe-Cu, Co-Cu, Co-A
u, Co-Pt, Mn-Al, Fe-Cr, Co-C
r, Ni-Cr, Fe-Co-Cr, Fe-Co-Cr
A ferromagnetic alloy such as -Ni. These may be a single-layer film or a multilayer film. Further, an underlayer or an intermediate layer may be provided between the nonmagnetic support and the metal magnetic thin film, or in the case of a multilayer film, to improve the adhesion between the layers and control the coercive force. Further, for example, in order to improve the corrosion resistance near the surface of the magnetic layer, it may be an oxide.

Further, a protective film layer may be formed on the magnetic layer. As this material, any material may be used as long as it is generally used as a protective film for an ordinary metal magnetic thin film. For example, carbon, Cr
O ₂ , Al ₂ O ₃ , BN, Co oxide, MgO, SiO
_{2, Si 3 O 4, SiN} x, SiC, SiN x -SiO
₂ , ZrO ₂ , TiO ₂ , TiC and the like. These may be a single-layer film or a composite film.

As the non-magnetic support, any conventionally known non-magnetic support can be used. For example, polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose triacetate, cellulose diacetate, cellulose derivatives such as cellulose acetate butyrate, polyvinyl chloride,
Vinyl-based resins such as polyvinylidene chloride, plastics such as polycarbonate, polyimide, and polyamide-imide;
Examples include paper, metals such as aluminum and copper, light alloys such as aluminum alloys and titanium alloys, and ceramic single crystal silicon.

As described above, the present invention relates to a magnetic recording tape cassette having a resin-made lid portion, wherein the phthalate ester contained as a plasticizer in the lid portion is used.
To 20 ppm.

According to the present invention, the amount of the phthalate ester contained in the lid portion of the magnetic recording tape cassette having the resin lid portion is set to 20 ppm or less, so that the phthalate ester adversely affects the magnetic tape. As a result, the deterioration of the dropout characteristics due to the deterioration of the magnetic tape can be suppressed to a practical level, and the durability of the magnetic tape can be ensured.

Further, by setting the amount of the phthalic acid ester contained in the lid portion to 1 ppm or more, the electrification of the magnetic tape can be prevented, and the stable running property of the magnetic tape can be secured.

[0060]

According to the present invention, the amount of the phthalate ester contained in the lid portion of the magnetic recording tape cassette having the resin lid portion is set to 20 ppm or less, so that the phthalate ester on the magnetic tape can be reduced. As a result, the deterioration of the dropout characteristics due to the deterioration of the magnetic tape can be suppressed to a practical level, and the durability of the magnetic tape can be secured.

Further, by setting the amount of the phthalic ester contained in the lid portion to 1 ppm or more, the electrification of the magnetic tape could be prevented, and the stable running property of the magnetic tape could be secured. .

[Brief description of the drawings]

FIG. 1 shows a perspective view of a magnetic recording tape cassette.

FIG. 2 shows an exploded view of the magnetic recording tape cassette.

FIG. 3 is a schematic view of a magnetic tape deposition apparatus.

[Explanation of symbols]

1 vacuum chamber, 2 non-magnetic support, 3 feed roll, 4
Take-up roll, 5 cooling can, 6, 7 guide roll, 8 crucible, 9 metal magnetic material, 10 electron gun, 1
3 shutter, 14 oxygen gas introduction pipe, 15, 16
Exhaust port, 100 magnetic recording tape cassette, 100a window, 101 upper shell, 102 lower shell, 103
Lid part, 103a front lid, 103b back lid, 120 magnetic tape, 200 reel, 2
01 upper flange, 202 lower flange, 203 hub

Claims (3)

[Claims] 1. A magnetic recording tape cassette, wherein a resin lid portion contains 1 to 20 ppm of a phthalic acid ester. 2. The magnetic recording tape cassette according to claim 1, wherein the lid part made of resin comprises a front lid and a back lid. 3. The magnetic recording tape cassette according to claim 1, wherein the lid part made of resin is composed of only a front lid.