JPS6096439A - Poly-p-phenylenesulfide film for vertical magnetizing - Google Patents

Abstract

PURPOSE:To obtain a vertical magnetizing base film whose thermal resistance is high, moisture uptake is less than that of polyester, the coefficient of linear expansion is small and maximum surface roughness becomes less than 500Angstrom , by making molecular orientation and heat setting of poly-p-phenylenesulfide. CONSTITUTION:Rear tension of more than 80kg/cm<2> is given to a poly-p-phenylenesulfide film at least, and the film is rolled into 1.5-4 times by pressure rolls which makes a pair and is falling within a temperature range of more than 60 deg.C and less than 140 deg.C through linear pressure of more than 100kg/cm at least and fixed thermally at a temperature of more than 220 deg.C and less than the fusion point. In addition to the above, thinning of the film can be done, as the film whose molecule has oriented extermely high is obtained when the film is orientated in the direction of a film width and orientation is applied to a longitudinal direction of the film also as well as rolling of the film. In this case, the film is orientated 1.5-4 times in the direction of the film width and 1.1-2 times in a longitudianl direction respectively at a temperature of more than 80 deg.C and less than 130 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a base film for perpendicular magnetization, which has a maximum surface roughness of 500X or less and is made of polyP-7 enylene sulfide with molecular orientation and heat setting.

The maximum surface roughness here is the surface roughness specified in JIS BO601, and can be measured by the stylus method.

Currently, magnetic recording plays a major role as external memory in tape recorders, VTRs, and other computers, and floppy disks are becoming increasingly important in office automation and personal computers in particular.

In this way, magnetic recording is used in the form of tape or disk, and polyester film is the mainstream as the base film. On the other hand, recently, a perpendicular magnetization method has been proposed in order to increase recording density, and development is progressing in the industry toward practical use. However, base films for vertical electromagnetization are required to have a smooth surface, good properties, heat resistance, low moisture absorption, and a small coefficient of linear expansion, and the existing commercially available films all have problems and are not practical.

For example, polyester film lacks heat resistance when forming a magnetic film, resulting in extremely poor productivity and impractical use.

In addition, in the case of polyimide film, which has good heat resistance, the magnetic film formation special number ζ cannot be applied to high vacuum due to the influence of absorbed moisture, and the film, magnetism, and film cannot be formed.

It is not practical due to insufficient adhesion strength and roughness of Table 5. On the other hand, the molecularly oriented and heat-set polyphenylene sulfide film of the present invention completely solves these problems; it has high heat resistance (melting temperature of -285°C) and hygroscopicity that is lower than that of polyester. -, the coefficient of linear expansion is small, and the maximum surface roughness is 500X or less due to molecular orientation, so it has all the characteristics necessary as a base film for perpendicular magnetization.

If the maximum surface roughness exceeds 500X, the smoothness of the surface 1 after forming the magnetic film will be insufficient, causing troubles due to contact with the recording/reproduction special number ζ main magnetic pole.

Therefore, the maximum surface roughness must be less than 500X.

As a result of extensive research on base films for perpendicular magnetization, the inventors of the present invention found that a film with a maximum surface roughness of 500X or less and made of molecularly oriented and heat-set polyphenylene sulfide has extremely excellent suitability, as described above. This is what led to the present invention.

It is preferable that the polyP-7 enylene sulfide used in the present invention is a polymer in which 90 or more moles of the structural unit consists of the structural unit, s-)-, and if it is less than 90 moles, the crystallinity decreases and This not only causes a decrease in heat resistance and mechanical properties, but also has an adverse effect on dimensional change characteristics.

Note that the polymer may contain other copolymer units as long as it is less than 10 moles of the structural units.

Such copolymer positions include, for example, trifunctional units (e.g. +
s-), ether units (e.g. Tsu-〇kaiS-), sulfone units (e.g. i-8o2()s-), meta bond units, and slight cross-linking can be caused by heating the polymerized polymer. It is also possible to do so. A method of reacting polyp-722 consisting of such structural units is preferred. In this case, in order to adjust the degree of polymerization, it is preferable to add a so-called polymerization aid such as an alkali or an alkali metal salt of a carboxylic acid.

It is appropriately determined depending on the type of catalyst used and the desired degree of polymerization. In addition, a swelling agent for the polymer is added to the polymerization system.
There is no problem in adding deterioration inhibitors, additives, etc.

Stretching and roll rolling can be cited as molecular orientation means for the polyphenylene sulfide film of the present invention.

Further, the present inventors further investigated the improvement of surface smoothness, which is particularly important for a base film for perpendicular magnetization, and found that the roll rolling method is an extremely excellent method. That is, in the case of stretching, the surface of the film is free, whereas in roll rolling, the surface is regulated by pressure rolls, so it has been found that a film with better surface smoothness can be produced. Note that it would be more effective if a liquid lubricant was used during rolling, but this is not a necessary condition. However, since roll rolling is basically a means of orienting molecules in the direction of the film's length, it can be used as is for tape applications, but when isotropy is required, such as in floppy disks, the film width It is preferable to also carry out molecular orientation in the direction, and stretching is necessary as a means for this purpose. In addition, tape applications are not limited to roll rolling.
By stretching the film in the mid-direction and also stretching it in the longitudinal direction, a film with extremely high molecular orientation can be obtained.
Can be made thinner.

In any case, the order of rolling and stretching may be carried out first. When rolling, the input side of the pressure roll must be at least 80Kl! /C112 or more rear tension must be applied.

Here, the backward tension, also called the extending force, is a force that acts in the opposite direction to the direction in which the film travels.
If it is lower than 01'f/a12, the neutral point (highest pressure point) of the pressure roll will shift to the roll entry side, making it more likely that defects will occur, making stable processing difficult. Therefore, it is necessary to apply a rear tension of 8°/2" or more.

Regarding the rolling temperature, the pressure roll should be set at 60℃ or higher for 1
It can be set arbitrarily within the temperature range □ of 40°C or less. If the temperature is lower than this range, a large number of pressure rolls will be required to obtain the desired rolling ratio, and a very large force will be required for applying pressure between the rolls, which will cause equipment problems. This is expensive equipment and is inappropriate for rolling conditions. On the other hand, if the temperature is higher than the grade temperature range (1) (well, rolling workability is not a problem, but surface smoothness, which is important due to perpendicular magnetization, is slightly deteriorated, so it is not preferable).

In addition, the line pressure must be 100 tsubo/or more, and 100 #
If it is lower than IP/cI+, sufficient orientation cannot be achieved.

Rolling is carried out by a factor of 1.5 to 4 times under the above conditions, but if it is less than 1.5 times, the orientation effect will be insufficient, and if it is rolled more than 4 times, breakage will occur frequently and stable processing will be difficult. Note that these things are the same in the case of stretching, and the magnification is 1.
5 to 4 times is good 0° and stretching, temperature is 80°C or higher, 130°
It is necessary to carry out the test in the range vB4 below ℃. If the temperature is lower than this range, uniform stretching will not be possible, resulting in a film with extremely poor thickness accuracy.On the other hand, if the temperature is higher than this range, crystallization will proceed and the yield stress will increase, making stretching difficult.

In addition, when not only rolling but also stretching is used in the longitudinal direction of the film, the appropriate stretching ratio is 1.1 to 2 times from the viewpoint of stable workability and orientation effect. Furthermore, heat setting is performed at temperatures above 220°C and below the melting point, but 220°C
If the temperature is lower than ℃, sufficient dimensional stability cannot be obtained.

Through the above steps, a base film suitable for perpendicular magnetization can be obtained.
A thin film of a magnetic substance such as 6-C9 alloy, iron oxide, C0-P alloy, Go-Ni alloy, CoP-Ni alloy, etc. can be formed. Thin film forming means include sputtering, vacuum evaporation, ion blating, electroplating, etc., and the base film of the present invention can be applied to any of them.

EXAMPLES Hereinafter, the present invention will be specifically illustrated by examples, but the present invention is not limited by these in any way.

Examples 1-2, Comparative Examples 1-3 Sodium sulfide 32.6 J'f (25
0 mol, crystalline water 4 Q wt), sodium hydroxide 100 g, lithium acetate 16.5 Kf (250 mol)
and N-methylpyrrolidone (79.2 mm) were charged, and the temperature was gradually raised to 205°C while stirring, and 7.0 mm of distillate containing 6.9 mm of water was removed. The remaining mixture contains 37.511 (255 mol) of 1,4-dichlorobenzene and N-
Methylpyrrolidone was added at 20 hours, and polymerization was carried out at 240°C for 8 hours.

The reaction product was washed with hot water 4 times, acetone 2 times, and methidichloride 21 times, and dried in a vacuum dryer at 80° C. for 24 hours to obtain PPS 224. The melt viscosity of the polymer was measured using a Koka type flow tester (manufactured by Shimadzu Corporation) under the conditions of a flow temperature of 300° C. and a shear rate of 200 (sec) −1, and was found to be 3200 poise.

The above PPS was pelletized using a 300 twin-screw Struder.

300% of the above polyP-phenylene sulfide pellets
Using an extruder, a raw film with a thickness of 0.2 t was created by extruding it from a T-die with a width of 400 mm. This raw film was rolled by a pair of pressure rolls having a diameter of 2600 mm and a surface length of 700 mm, and was further heat set.

did. Table 1 shows the processing conditions and maximum surface roughness measurements.
Shown below.

Examples 3 to 4, Comparative Examples 4 to 5 Raw films prepared in the same manner as in Example 1 were rolled or longitudinally stretched, and then laterally stretched, and then heat set. The maximum surface roughness of the obtained film was measured and determined in the same manner as in Example 1. Table 1 shows the processing conditions and maximum surface roughness measurement results.

Example 5 A raw film prepared in the same manner as in Example 1 was rolled,
Further, after transverse stretching and longitudinal winding I, heat setting was performed. The maximum surface roughness of the obtained film was measured in the same manner as in Example 1. Table 1 shows the processing conditions and maximum surface roughness measurement results.

Example Vermilion Permalloy with an average thickness of 3000λ was deposited on both sides of the film obtained in Example 3 by sputtering as a soft magnetic layer, and then 2
0% cr-c.

By flying the alloy, it was possible to easily and stably form a perpendicularly magnetized film with an average film thickness of 50,005 mm.

Comparative Example 6 An attempt was made to fly permalloy and 20% cr-co alloy using a 50 μm extruded film of polyP-phinyl disulfide in the same manner as in Example 4, but the sputtering failed. The film was deformed and a good product could not be obtained.

Comparative Examples 7-8 Commercially available polyester film (Toshi, Lumirror ■) 50μ
product and polyimide film (Dupont, Ka
pton H type) 50. Example 4 using product a
Permalloy and 20% CrC with a similar methodology as
An attempt was made to fly the O alloy, but Lumirror ■ had a low heat resistance of 5, so the productivity was extremely poor and it was not practical.

Regarding KaptOn■, a high vacuum could not be obtained due to the absorbed moisture, and the adhesion between the magnetic layer and the film was poor and the film easily peeled off. In addition, even before peeling, the flat surface smoothness was poor and a good product could not be obtained.

Claims (4)

[Claims] (1) PolyP-phenylene sulfide is molecularly oriented and heat set and has a maximum surface roughness of 500 Å or less. Base film for perpendicular magnetization. (2) Applying a rear tension of at least 80 kl//cs2 to the polyP-phenylene sulfide film,
Using a pair of pressure rolls in a temperature range of 0°C or higher and 140°C or lower, the product is roll-rolled 1.5 to 4 times at a linear pressure of at least 100 KP/cI+1 and at a temperature of 220°C or higher and below the melting point. The base film for perpendicular magnetization according to claim FIILti+, characterized in that it is heat-set. (3) A backward tension of at least 80 #/am2 is applied to the polyP-phenylene sulfide film, and a tension of at least 100 #/3 is applied to the polyP-phenylene sulfide film by a pair of pressure rolls in a temperature range of 60°C to 140°C. Roll rolled to 1.5 to 4 times with linear pressure, and heat the film at 80°C or higher at 130°C in the direction of the film.
Stretched 1.5 to 4 times at a temperature below ℃, and further stretched at 220℃
The base film for perpendicular magnetization according to claim 1, characterized in that it is heat-set at a temperature above the melting point or below. (4) Apply a rear tension of at least 80hg/am2 to the polyP-phenylene sulfide film and heat it at 60°C.
1.5 with a linear pressure of at least +00 marks/cm or more using a pair of pressure rolls in a temperature range of 140°C or more.
Roll rolled to ~4 times, stretched 1.5 to 4 times in the film width direction and 1.1 to 2 times in the film length in each direction at a temperature of 80 ° C or more and IIO ° C or less, and further stretched 220 ° C or more and below the melting point. The base film for perpendicular magnetization according to claim (1), wherein the base film is heat-set at a temperature of . +5) Ho! The JP-7 enylene sulfide film is heated to a temperature of 1.5 to 4 times in the film length direction and/or film width direction at a temperature of 80°C or higher and 130°C or lower, respectively.
The base film for perpendicular magnetization according to claim (1), which is further heat-set at a melting point of 220°C or higher and a temperature of 220°C or lower.