JPH03203813A - Magnetic tape - Google Patents

Abstract

PURPOSE:To improve a traveling property and S/N by specifying the surface roughness expressed by the average value of the space wavelength on the rear surface of a magnetic tape. CONSTITUTION:The surface roughness n the rear surface of the magnetic tape in a magnetic recording and reproducing device is confined within 0.5 to 1.0mum width selected from a 4.5 to 8.0mum range in the average value of the space wavelength at the time of magnetic recoding and reproducing. The space wavelength referred to here signifies the value 2pi/omega obtd. from the spatial angular frequency a determined by inputting the measured data, and making Fourier transform with the respective sinusoidal functions is assuming the surface rougheness distributing on line or plane as a simusoidal function having various amplitude A and special angular frequency omega. Both of the S/N and the traveling property are improved in this way.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a magnetic tape for magnetic recording and reproducing, which is formed by forming a magnetic coating film on the surface of a base film, and particularly relates to a magnetic tape for magnetic recording and reproducing in which a magnetic coating film is formed on the surface of a base film. This invention relates to technology for improving the S/N ratio and running performance during recording and reproduction of magnetic tape.

(Prior art) In recent years, magnetic recording media such as magnetic tapes have become denser and have higher S/S.
The N conversion is remarkable, allowing high-density recording and playback, and S
In order to obtain these magnetic recording media with a high /N ratio, the surface of the magnetic layer tends to be increasingly smoothed.

Here, in order to make the surface of the magnetic layer smooth, the surface of the support must also be made smooth in order to avoid the transfer of unevenness from the surface of the support such as a base film to the magnetic layer. With regard to media, as the density and S/N of magnetic recording media have increased, the running properties of the magnetic recording media have tended to deteriorate.

Therefore, in the past, the surface roughness TAR value (μm) of the base film was set to less than 0.015, and the number of protrusions per unit area, that is, the PCC value (unit side/mm')
(Japanese Patent Application Laid-Open No. 61-112629), ■
2. The average particle diameter is larger than 0.5 μm on the back side of the support.
Technology for improving the runnability of magnetic recording media, such as providing a back coat layer comprising a binder and non-magnetic powder whose maximum particle diameter is less than 0 and whose maximum particle diameter is 5 μm or less (Japanese Patent Application Laid-open No. 136913/1983). is proposed.

(Problem to be solved by the invention) However, in the technique (■) above, the PCC value is 80
Although it is said to be greater than 0, JP-A-61-11262
The range considered in the example of No. 9 is 600 to 21
00, which is within the range of 20 μm to 50 μm when converted into spatial wavelength.

If a surface roughness range with a large spatial wavelength is used as the back side of a magnetic tape and is slid through a magnetic recording/reproducing device, the surface roughness corresponding to the height of the protrusion measured by R1 or SR, for example. Even if the roughness is within the appropriate range, subtle vibrations occur when the magnetic tape runs, and these vibrations increase the noise level, and in the case of video tapes, when recording and playing back with a video device, especially C. -5/N ratio, that is, a decrease in the S/N ratio of the chroma signal occurs.

In addition, when improving the running properties of a magnetic tape by using non-magnetic powder in the back coat layer, it is possible to create a magnetic tape that has both excellent running properties and the above-mentioned S/N ratio by simply controlling the particle size of the non-magnetic powder. It does not mean that you will get

Although it depends on the magnetic recording and reproducing device such as a video tape recorder (VTR), the above technology
Suitable ranges containing 5 to 60% by weight of the non-magnetic powder described in No. 913 based on the entire back coat layer include, for example, VHS (registered trademark of Japan Victor Co., Ltd.) system, 5-VH5 system, and 8mm When manufacturing video tapes using this method, the spatial wavelength of the surface roughness is large, and subtle vibrations occur when the magnetic tape runs.
This vibration increases the noise level, and the above-mentioned C-S/N
A decrease in the ratio occurs. Here, if the ratio of the non-magnetic powder to the entire back coat layer is constant, as the particle size of the non-magnetic powder increases, the spatial wavelength in the surface roughness of the back surface of the magnetic tape increases, and the above-mentioned S/N ratio decreases further. growing.

As described above, in the past, it has not been possible to obtain a magnetic tape such as a video tape that satisfies both running performance in a magnetic recording and reproducing device and S/N ratio during recording and reproducing.
There is a need for a magnetic tape that satisfies these requirements.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention has a surface roughness of 4.5 mm on the average spatial wavelength of the back surface of a magnetic tape that slides in a magnetic recording and reproducing apparatus during magnetic recording and reproducing. The width is selected from the range of 5 μm to 8.0 μm and is within the range of 0.5 μm to 1.0 μm.

Note that the spatial wavelength referred to here refers to the surface roughness distributed on a line or plane as a sine function with various amplitudes A and spatial angular frequencies ω, and by inputting the measured data and using a Fourier method for each sine function. It means the value 2π/ω obtained from the spatial angular frequency ω obtained by transformation.

Further, the magnetic tape of the present invention may or may not have a back coat layer formed on the back surface of the base film.

If a back coat layer is not formed, the back surface of the base film becomes the back surface of the magnetic tape, but the surface roughness of the back surface of the base film can be reduced by adding an appropriate non-magnetic powder (filler) at the base film manufacturing stage. ), or by performing surface control or texture treatment during calendering, etc., by a known method.

In addition, the surface roughness of the back coat layer, which is the back surface of the magnetic tape on which the back coat layer is formed, can be formed by filling an appropriate non-magnetic powder (filler) in the film manufacturing stage. When filling an appropriate non-magnetic powder in the step, the average particle size of the non-magnetic powder is It is preferable to set it as less than 0.5 micrometer.

(Function) When the surface roughness expressed as the average value of the spatial wavelength on the back side of the magnetic tape is in the range of 4.5 μm to 8.0 μm, the C-3/N ratio decreases as the spatial wavelength increases, and conversely, the C-3/N ratio decreases as the spatial wavelength increases. The 3/N ratio, that is, the S/N ratio of the luminance signal becomes better. If this spatial wavelength exceeds the predetermined width selected from the range of 4.5 μm to 8.0 μm, Y-3/N during recording and reproduction.
Either the ratio or the C-3/N ratio becomes poor.

(Example) The present invention will be explained in more detail with reference to Examples below.

(Examples 1 to 3. Comparative Examples 1 to 4) Iron alloy magnetic powder: 300 parts by weight Polyvinyl butyral: 60 parts by weight Polyurethane resin
... 60 parts by weight polyisocyanate resin...
20 parts by weight Cr2O3 -15 parts by weight Carbon black...20 parts by weight Cyclohexanone:...400 parts by weight Toluene
...400 parts by weight of the above composition was kneaded in a ball mill for 24 hours and applied to the surface of the base film to form a magnetic layer.

Further, a back coat layer was formed by applying a paint required for bank coating to the surface of the base film, and a paint with the following composition was used as the paint for the back coat layer.

Calcium carbonate...00 parts by weight Vinyl chloride
... 30 parts by weight polyurethane resin
... 30 parts by weight polyisocyanate resin... 1
0 parts by weight Cyclohexanone...200 parts by weight Toluene...200 parts by weight The paint required for bank coating used here is back coat layer paint A1 in which the average particle size of calcium carbonate, which is a non-magnetic powder, is 0.18 μm. 0.25 μm back coat layer paint B, and 0.25 μm back coat layer paint B.
There are three types of paints CI that require bank coating of 5 μm, and by adjusting the processing speed and nip pressure during calendering, the average spatial wavelength and surface roughness SR shown in Table 1 can be achieved.
The magnetic tapes of Examples 1 to 3 and Comparative Examples 1 to 4 having
videotape) was obtained.

Y of the magnetic tapes of Examples 1 to 3 and Comparative Examples 1 to 4 above
-3/N ratio and C-5/N ratio are EV- manufactured by Sony Corporation.
In addition to measuring with an 8mm VTR device known as A300 and an NTSC noise meter manufactured by Shibatsu,
The running performance was evaluated by repeatedly running in this VTR device,
The results shown in Table 1 were obtained. In the table, ◯ indicates good, △ indicates slightly poor, and × indicates poor.

Table 1 From the results in Table 1, it can be seen that the surface roughness of the back surface of the magnetic tape that slides in contact with various guide pins including the guide bin in the half of the VTR device, rolls, head drums, etc. The magnetic tapes of Examples 1 to 3, ie, 8 mm video tapes, which have an average value of 4.5 μm to 5.0 μm, have good Y-3/N ratios and C-5/N ratios.

On the other hand, the magnetic tapes of Comparative Examples 1 and 2, in which the spatial wavelength was less than 4.5 μm on average, had poor Y-S/N ratios of 5.0 μm.
The magnetic tapes of Comparative Examples 3 and 4 with a C-S/N exceeding μm
It can be seen that the ratio is inferior.

In addition, the runnability of the magnetic tape on which the back coat layer is formed is determined by the S
It can be seen that it varies depending on R, and is bad when SR is less than o and oto, and good when SR is 0.010 or more.

(Examples 4 to 6. Comparative Examples 5 to 8) The iron alloy magnetic powder in the composition used when forming the magnetic layers of Examples 1 to 3 and Comparative Examples 1 to 4 was coated with cobalt γ-F.
e203, 30 parts by weight of polyvinyl butyral,
The polyurethane resin was 40 parts by weight, cyclohexanone and toluene were each 300 parts by weight, and the composition was the same as that of the paint for the back coat layer when forming the back coat layer, and each had an average particle size of calcium carbonate of 0.2 μm.
The average spatial wavelength shown in Table 2 was obtained in the same manner as in Examples 1 to 3 and Comparative Examples 1 to 4, except that three types of back coat layer paints A2, B2, and C2, which were different in diameter from 0.27 μm to 0.55 μm, were used. and surface roughness SR.

The magnetic tapes of Examples 4 to 6 and Comparative Examples 5 to 8 having
videotape) was obtained.

Y of the magnetic tapes of Examples 4 to 6 and Comparative Examples 5 to 8 above
-3/N ratio and C-3/N ratio were determined using the 5-VH5 system VH5 known as HR-S7000 manufactured by Victor Company of Japan.
In addition to measuring with a TR device and an NTSC noise meter manufactured by Sibaku Corporation, the running performance was evaluated by repeatedly running in this VTR device, and the results shown in Table 2 were obtained. The meanings of the symbols O1Δ and × in the table are the same as in Table 1.

Table 2 From the results shown in Table 2, the surface roughness of the back coat layer sliding in the VTR device is 5.5 μm to 6 μm in average spatial wavelength.
．． The magnetic tapes of Examples 4-6 which are 5 μm, i.e. 5-V
The H3 videotape has good Y-3/N ratio and C-3/N ratio. On the other hand, the magnetic tapes of Comparative Examples 5 and 6 in which the average spatial wavelength was less than 5.5 μm were Y-3
It can be seen that the magnetic tapes of Comparative Examples 7 and 8, which have a poor C-3/N ratio and a diameter exceeding 6.5 μm, have a poor C-3/N ratio.

In addition, the running properties of a magnetic tape with a back coat layer formed thereon vary depending on the SR of the back coat layer surface, which is the back surface of the magnetic tape.If the SR is less than 0.010, it is poor; It can be seen that the condition is good.

(Examples 7 to 9. Comparative Examples 9 to 12) Polyvinyl butyral in the composition used when forming the magnetic layers of Examples 4 to 6 and Comparative Examples 5 to 8 was 40 parts by weight, and the back coat layer was Three types of back coat layer paints A3, Bs, and C8 having the same composition but different average particle diameters of calcium carbonate of 0.2 μm, 0.3 μm%, and 0.6 μm were used for the back coat layer paints during formation. The magnetic tapes of Examples 7 to 9 and Comparative Examples 9 to 12 (video tape) was obtained.

Next, the Y-3/N ratio and C-3/N ratio of the magnetic tapes of Examples 7 to 9 and Comparative Examples 9 to 12 were determined using V known as HR-37000 manufactured by Victor Company of Japan. )(S
The vehicle was measured using a VTR device and an NTSC noise meter manufactured by Sibaku Corporation, and the running performance was evaluated by repeatedly running the vehicle in this VTR device, and the results shown in Table 3 were obtained. The meanings of the symbols ○, Δ, and × in the table are the same as in Table 1.

(Hereinafter, blank space) From the results in Table 3, it can be seen that the surface roughness of the back coat layer that slides in the VTR device is 7.0 μm to 8 μm in average spatial wavelength.
．． The magnetic tapes of Examples 7 to 9 (VH
3 videotape) has good Y-S/N ratio and C-3/N ratio. On the other hand, the magnetic tapes of Comparative Examples 9 and 10 in which the average spatial wavelength was less than 7.0 μm were Y-
Comparative Examples 11 and 1 with poor 3/N ratio exceeding 8.0 μm
It can be seen that the magnetic tape No. 2 has an inferior C-3/N ratio.

In addition, the runnability of the magnetic tape on which the back coat layer is formed is determined by the S
It can be seen that it changes depending on R, and is bad when SR is less than 0.010 and good when SR is more than o.

(Examples 10 and 11, Comparative Examples 13 to 16) Iron alloy magnetic powder with the following composition was placed on a base film whose back surface had the average spatial wavelength and SR as shown in Table 4...30
0 parts by weight Polyvinyl butyral 40 parts by weight Polyurethane resin 60 parts by weight Abrasive
... 15 parts by weight carbon black
... 20 parts by weight cyclohexanone ...30
After mixing and dispersing a composition consisting of 300 parts by weight of 0 parts by weight toluene, 20 parts by weight of an isocyanate curing agent is added and further dispersed, and the resulting coating liquid is applied to the surface of the base film for orientation. ,calendar,
Through predetermined steps such as curing, magnetic tapes (video tapes) of Examples 10 and 11 and Comparative Examples 13 to 16 were obtained.

These magnetic tapes were measured and evaluated in the same manner as Examples 1 to 3 and Comparative Examples 1 to 4, and the results shown in Table 4 were obtained.

Table 4 As is clear from the results in Table 4, the Y-3/N ratio and C-
Regarding the S/N ratio, the magnetic tapes of Examples 10 and 11 and Comparative Examples 13 to 16, in which no back coat layer was formed, were compared to the magnetic tapes of Examples 1 to 3 and Comparative Examples 1 to 4, in which back coat layers were formed.
shows a similar trend.

However, unlike in Examples 1 to 3 and Comparative Examples 1 to 4, it is found that the limit of running performance of the magnetic tape is at a point where SR is approximately 0.011 μm.

(Examples 12 and 13, Comparative Examples 17 to 20) Iron alloy in the composition used when forming a magnetic layer on a base film whose back surface has the average spatial wavelength and SR shown in Table 5. Magnetic tapes (video tapes) of Example 12.13 and Comparative Examples 17 to 20 were obtained in the same manner as in Example 10.11 and Comparative Examples 13 to 16 above, except that the magnetic powder was changed to cobalt-coated γ-Fe203. Ta.

These magnetic tapes were measured and evaluated in the same manner as Examples 4 to 6 and Comparative Examples 5 to 8, and the results shown in Table 5 were obtained.

Table 5 As is clear from the results in Table 5, the Y-3/N ratio and C-
Regarding the 3/N ratio, the magnetic tapes of Examples 12 and 13 and Comparative Examples 17 to 20 in which a back coat layer was not formed were also compared to Examples 4 to 6 and Comparative Examples 5 to 8 in which a back coat layer was formed.
shows a similar trend.

However, unlike in Examples 4 to 6 and Comparative Examples 5 to 8, it is found that the limit of running performance of the magnetic tape is at a point where SR is approximately 0.011 μm.

(Examples 14 and 15, Comparative Examples 21 to 24) In the same manner as in Examples 12 to 13 and Comparative Examples 17 to 20, the average spatial wavelength and SR of the back side were the values shown in Table 6. Magnetic tapes (video tapes) of Examples 14 and 15 and Comparative Examples 21 to 24 were obtained.

These magnetic tapes were used in Examples 7 to 9 and Comparative Examples 9 to 12.
Measurement and evaluation were carried out in the same manner as above, and the results shown in Table 5 were obtained.

Table 6 As is clear from the results in Table 6, the Y-3/N ratio and C-
Regarding the S/N ratio, the magnetic tapes of Examples 14 and 15 and Comparative Examples 21 to 24, in which no back coat layer was formed, were compared to the magnetic tapes of Examples 7 to 9 and Comparative Examples 9 to 1, in which back coat layers were formed.
It shows the same tendency as 2.

However, unlike in Examples 4 to 6 and Comparative Examples 5 to 8, it has been found that the limit of the running performance of the magnetic tape is at a point where SR, is approximately between 0.012 and 0.015 μm. be done.

(Effects of the Invention) As is clear from the above examples, according to the present invention,
A magnetic tape is provided that has both a Y-3/N ratio and a C-S/N ratio superior to those of the prior art.

Therefore, by appropriately selecting R1 and SR according to the base film and back coat layer exposed on the back side of the magnetic tape, or the running conditions of the magnetic recording/reproducing device, both the S/N ratio and running properties of these can be improved. We can provide excellent magnetic tape for

Claims (1)

[Claims] (1) In a magnetic tape for magnetic recording and reproducing in which a magnetic coating film is formed on the surface of a base film, the surface roughness of the back surface of the magnetic tape that slides in a magnetic recording and reproducing device during magnetic recording and reproducing is measured in terms of spatial wavelength. Average value 4.5μm to 8.0μm
A magnetic tape characterized by having a width of 0.5 μm to 1.0 μm selected from the range of 0.5 μm to 1.0 μm.