JPS6228918A - Magnetic recording tape - Google Patents

Abstract

PURPOSE:To increase the holding power, to eliminate drop-out of recording and to improve the traveling property and durability as the recording tape by forming a magnetic layer on one surface of a carrier and coating a coated film contg. a lubricant on the other surface. CONSTITUTION:The 5% elongation stress in the lengthwise direction of the tape is regulated to >=18kg/mm<2>, the Young's modulus in the lengthwise direction is controlled to >=800kg/mm<2>, the Young's modulus in the widthwise direction is adjusted to >=500kg/mm<2> and the surface roughness is regulated to <=0.005mum. Biaxial oriented polyethylene-2,6-naphthalene dicarboxylate film is used as the carrier. A magnetic layer consisting of a metallic thin film is formed on one surface of the carrier and a coated film of an org. high polymer contg. a lubricant is formed on the other surface on which a metallic thin film is not formed. Consequently, the holding power, when used as a magnetic recording tape, is increased, drop-out of recording is eliminated and the traveling property and durability as the recording tape can be improved even when the tape is thin.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a magnetic recording tape, particularly a magnetic recording tape for VTR, and relates to an improved magnetic recording tape that enables long-time recording. Related to tape.

[Prior art]

Magnetic recording tape and L'''C, conventionally biaxially oriented d4
A magnetic tape is used in which a magnetic layer consisting mainly of r-iron oxide and polymer binder is formed on at least one side of the surface of a polyethylene terephthalate film. However, these conventional magnetic tapes are as follows:
It had such drawbacks. That is, (1) the coercive force as a magnetic recording tape is small.

(2) When used as a magnetic recording tape, if the tape thickness is reduced, the running performance and durability of the magnetic recording tape will be affected, and recordings will drop out (dropout), so it can be wound into a cassette of a certain size. Due to the limitations of tape 1, it is not possible to record for a long time.

For this reason, especially in recent years, with the miniaturization of home VTRs, the T-beam width has decreased from 12.7 mm to 8 mm, and cassettes have also become smaller. There was no satisfactory magnetic recording tape available due to the technology involved.

[Objective of the Invention J The object of the present invention is to solve the above-mentioned drawbacks, and to provide a magnetic recording tape with a high coercive force, no recording dropout, and even when made thin, it has good runnability and durability as a magnetic recording tape. The present invention aims to provide a magnetic recording tape with extremely good properties.

[Structure of the invention]

The present invention uses a biaxially oriented polyethylene-2,6-naphthalene dicarboxylate film with specific mechanical properties and surface structure as a support, and a magnetic layer made of a metal thin film on one of the surfaces of this support. This magnetic recording tape is made by coating a coating film of an organic polymer containing a lubricant on the opposite surface of the support on which the magnetic metal thin film is not formed.

The film that serves as the support for the magnetic recording tape of the present invention has a stress (referred to as F -5 x under J) of 1 when elongated by 5% in the longitudinal direction.
8 kg/ul 39.17, the Young's modulus in the longitudinal direction is 800 k[/mu or more, the Young's modulus in the width direction is 500 kg/m or more, and the surface roughness is based on the measurement method θyu described later. Biaxial internal P-oriented polyethylene-2,6 characterized by having a diameter of 1,005 rim or less
- naphthalenedicarpoxylate. In short, the support for the magnetic recording tape of the present invention has a high Young's modulus, little dimensional change due to stress, and a smooth surface. And polyethylene-2, which has excellent heat resistance,
6-naphthalene dicarhogine 1/- is combined with the support film to form a thin metal film on the surface of the lever. A coating film containing a lubricant is coated on another surface to prevent distortion and runnability during use.This is a magnetic recording tape that has no problems.1 In addition to this structure, the tape as a whole Since the thickness of the tape can be reduced to less than 10 μm, the length of the tape that can be stored in a cassette unit can be increased, the recording time can be significantly extended, and the distortion of recording during recording and playback due to the high Young's modulus can be reduced. , Nukyu, etc. have also been improved like Tobisu.

To further explain the present invention, the Young's modulus of the support film in the longitudinal direction in the present invention is preferably 800 to 1600 kg/excitation l. If the Young's modulus exceeds 16ookg/mt, the tape may tear, which is not preferable.

Also, the Young's modulus in the width direction is 500 kg/a'~70
0 kg/l1m is preferred. When the Young's modulus in the width direction is less than 500 kg/sr, the tape tends to be wrinkled or scratched in the width direction when the tape is repeatedly run. If this value exceeds 700 kg/m, a biaxially oriented polyethylene 2.6 naphthalate film that satisfies a longitudinal Young's modulus of 1000 kg/m or more at 161 hours can be obtained by simple or ordinary stretching means. It is no longer a good idea to do so because it is difficult to do so.

In the present invention, as a support film having a surface roughness of 0.005 μm or less, element periodic coatings No. ■A and No. 11F! ,
Total 0.1 of inorganic particles containing elements of group 1VA and group ①B
Form the surface by containing less than % of mold needles! 7. It can also be formed by other surface treatments. With the biaxial orientation method (7), the film may be stretched simultaneously in the vertical direction using a general roll or stenter, or it may be stretched sequentially in the vertical and horizontal directions [7].

The magnetic metals constituting the tape of the present invention include cobalt,
Iron, nickel, an alloy thereof, or an alloy of these with chromium or tungsten is used.

The metal thin film is formed by wet summer air deposition using electroless plating or electrolytic plating, or by dry method using sputtering or ion blasting. In particular, the vacuum source N method is the most preferred forming method because it has an extremely high deposition rate and can obtain a high coercive force. Thin 5・ν is 300=15
The standard thickness is about 0.00 im (0.3-', 5 um).

Next, the surface of the support on which the magnetic thin film is not formed is coated with a coating of shoulder shell polymer containing a lubricant in order to maintain full running properties as a tape. Aluminum acrylate is used as a lubricant.

Examples include molybdenum, #fine silica, and fluororesin. The lubricant is an organic polymer with adhesive strength to the support film (for example, polyether containing glycysyl ether of polyoxyalkylene chloride, naphthalene-2,6
- By dispersing a dicarboxylic acid in a solution or emulsion of a copolymerized polyester having an acid component modified with an aliphatic dicarboxylic acid, etc., and applying this to the surface of the support, slippage and running properties can be improved. A magnetic recording tape is obtained. The lubricant layer may be as thin as 1 μm or less, or about 50 to 500 nm.

The thickness of the tape used in the present invention is preferably 3 to 10 μm. If the thickness is less than 3 μm, the running properties and durability of the tape will be poor, while if the thickness is 10 am or more, the purpose of long-term recording cannot be achieved.

〔Effect of the invention〕

The present invention is based on an organic polymer in which a magnetic metal thin film is formed on one side of the surface of a naphthalene film having a surface roughness of 0.005 rim or less, and a lubricant is dispersed on the other side. Since it is formed with a thin coating film, it has a large coercive force as a magnetic recording tape, and the stress at 5% elongation in the length direction is 18 kg/m or more, and the Young's modulus is 80 kg/m.
Since it is made from a biaxially oriented polyethylene 2,6 naphthanedicarpoxylate film with a Young's modulus in the width direction of 500 kg/m or more, even if the thickness is 10 am or less as a magnetic recording tape, the tape running properties and The durability is good, and even in Beta type and BIIlffi type cassettes of home VTRs, the thickness of the magnetic recording tape can be made thinner, making it possible to record for a long time.

〔Example〕

Next, embodiments of the present invention will be described based on Examples.

Various physical property values and characteristics in the present invention were measured and defined as follows.

+11 Young's modulus measurement film was cut into 10 mm and 15 ann length samples, and stretched using an Instron type universal tensile tester at a tension speed of 10 mm/min and a chart speed of 500 III/min with a chuck gap of 100 inches. Young's modulus was calculated from the tangent to the rising portion of the obtained load-elongation curve.

Measurement of +21F-5 value When measuring the Young's modulus described above, it was determined from the stress at 5% tension when the tensile speed was 200 ma/min and the chart speed was '1'00 am/min.

(3) Film surface roughness R'a) JIS B 0
Measure the garden according to 601. Using a stylus-type surface roughness needle (SURFCOM 3B) manufactured by Tokyo Seimitsu Co., Ltd., the radius of the needle is 2.
A chart (film surface roughness curve) was drawn under conditions of 7/myo, load o, and b 7 g. Extract a portion of measurement length L from the film surface roughness curve in the direction of its center line,
The center line of this cut-out part is the X axis, and the direction of the vertical multiplication base is Y.
When the roughness curve is expressed as Y=f(x) as the axis, the value (i(a:Bm)) given by the following equation is defined as the film surface roughness.

In the present invention, the reference length is set to 0.25 mm, 8 pieces of "'C are measured, and the average value of 5 pieces excluding 3 pieces from the largest value is R.
represents a.

-10= (4) Measure magnetic properties such as coercive force magnetic recording with a sample vibrating magnetometer,
The coercive force was determined from the hysteresis curve.

When the coercive force was 5000e (Oersted) or more, the coercive force was determined to be good, and when it was less than 5000e, the coercive force was determined to be poor.

(5) Dropout magnetic tape is run continuously for 100 hours on a home-use video table refuter (helical scan). That tape 4
After being kept at 0°C for 48 hours, the tape was returned to room temperature and recorded and played back, and a dropout counter was used to count the number of tapes with a signal output of 50% or less.

In addition, the measurement is 1/2 inch width and 780 m as one roll.
Measurement was performed for 0 rolls, and when the number of pieces per roll was less than 2, it was judged as drop-out: good, and when there were 2 or more pieces, it was judged as all-out/out: bad.

(6) Running properties of magnetic recording tape The tape was set in a home-use video tail coater (Calscan) and run for 100 hours, repeatedly starting and stopping 17 times, to examine the running condition and measure the output.

In this run, if all of the m-th items below were satisfied, the running performance was determined to be good, and if not, the running performance was determined to be poor.

■ The tape will not bend or become seaweed-like.

Q) There is no tape squeal while driving.

■) The tape will not run out or break.

(7) Curl A square sample of 500 x 500 mm was cut from the original tape for magnetic recording, and its curl condition was classified into the following five grades: D and EVi curl: good; A, B, and C: curl:
It was determined to be defective.

A: Completely cylindrical.

The condition is similar to BAA, but a part of the tube is open.

This is a CAB with a widened opening, but the longest part of the side surface is the diameter of a circle.

D: The open FJ part of C is wider, and the longest part of the side surface cannot be the diameter of the circle.

E: No or almost no curl.

Examples, Comparative Examples 1 to 4 Pellets of polyethylene 2.6 naphthalene dicarpoxylate with an intrinsic viscosity of 0.60 containing fl, Q5 % of silica with an average particle size of 0.15 μm were dried at 170° C. for 4 hours. did. This polymer was melt-extruded according to a conventional method.
L, an unstretched film with a thickness of 7028 m was prepared, and the VCI was 4.5 times in the machine direction at 20'C and 130°C in the transverse direction.
Biaxial stretching was carried out sequentially by 4.0 times at
Heat fixation was performed for 0 seconds to complete a 6arn film.

In addition, before heat setting, the biaxial stretched film was coated with a coating liquid having the following composition on one side of the film surface.

Composition of the coating liquid applied to the film surface: 0 Aluminum acrylate (Asada Chemical Co., Ltd., P-30)
2wt% solution・・・・・・12kgO polyethylene glycol (manufactured by NOF Corporation, molecular weight 19,000) 2wt% solution・・・・・・・・・・・・5kgO polyethylene glycol diglycidyl ether (manufactured by Nagashio Sangyo N)
EROI O■) 2wt% solution・・・・・・・・・・・・
...2 kgO polyoxyethylene nonylphenyl ether 2wt% solution...
...1 kg application ii! - is about 2.2 when wet
g/rn', and the solid content and [7 are approximately 0.0126 g
/Awakening.

This polyethylene 2.6 naphthalenedicarpoxylate 1
・Co-N with a thickness of 1000A was deposited on the remaining surface of the film by electron beam evaporation (oblique evaporation at 50° to a small Nl entrance).
A layer (Co/Nr 75/25 heavy leaf ratio) was deposited to obtain an original fabric for magnetic i1 recording.

When this raw material is used as a magnetic tape, the properties as shown in the ViMI table include coercive force and dropout.

Both running properties were good. However, when the polynomal and inorganic particles were outside the scope of the present invention (Comparative Example 1゜2),
No matter how hard we try, we have not been able to obtain a base film for magnetic recording media that has good coercive force, dropout, and runnability. In addition, when the content of inorganic particles was outside the scope of the present invention (Comparative Examples 3 and 4), no matter how hard we tried, it was not possible to obtain a film with good coercive force, drop anide, and runnability. .

Examples 2-4. Comparative Examples 5 to 10 Using the same glue force and polyethylene 2.6 naphthalene dicarphoquinelate gold as the actual MA91J1, the glue balance amount and film forming conditions were changed [7 to create a biaxially oriented film with the same film properties. Had made. Table 2 shows the properties of these films as magnetic recording media. As can be seen from Table 2, when the physical properties of the film are within the scope of the present invention (Example 2
~4) A magnetic tape with good coercive force, good dropout, and good runnability as well as good curling can be obtained.7'
did. However, in cases where the physical properties of the film are outside the scope of the present invention & (Comparative Examples 5 to 9), the coercive force.

You can't get magnetic tape that has excellent drop out and runnability.

Claims (1)

[Claims] 1) The 5% elongation stress in the length direction is 18 kg/mm^2 or more, the Young's modulus in the longitudinal direction is 800 kg/mm^2 or more, and the Young's modulus in the width direction is 500 kg/mm^2. 2 or more and a surface roughness of 0.005 μm or less, a support made of a biaxially oriented polyethylene-2,6-naphthalene dicarboxylate film, and a magnetic material formed on one surface of the support. A magnetic recording tape comprising a thin metal film and a coating film made of an organic polymer containing a lubricant coated on the other surface of the support. 2) The magnetic recording tape according to claim 1, wherein the magnetic metal thin film is made of cobalt, iron, nickel, an alloy thereof, or an alloy of these with chromium or tungsten. 3) Consisting of a magnetic metal thin film, a support and a coating film with a thickness of 1
Claim 1 characterized in that it is 0 μm or less
2. The magnetic recording tape according to item 1 or 2.