JPS59185029A - Magnetic recording flexible disc - Google Patents

Abstract

PURPOSE:To obtain a film having excellent dimensional stability and to prevent generation of a tracking error with said film as a base by adjusting the expansion coeffts. with temp. and humidity of the biaxially oriented film consisting of poly-para-phenylene sulfide. CONSTITUTION:Poly-para-phenylene sulfide which is a base film is required to be incorporated at >=90mol%, and if the content is <=90mol%, the crystallinity of the polymer decreases and the expansion coefft. with temp. increases. The use of a magnetic disc is made possible in a wide temp. and humidity range when the film satisfies the conditions; 9-35X10<-6> deg.C<-1>, more preferably 9-25 the max. expansion coefft. with temp. at the plane inclusive of the longitudinal and transverse directions of said film, 0-5.0X10<-6>%RH<-1> (more preferably 0-2.5X10<-6>% RH<-1>) the max. expansion coefft. with humidity, 0-8.0X10<-6> deg.C<-1> (more preferably 0-5.0X10<-6> deg.C<-1>) difference between the max. value and min. value of the expansion coefft. with temp., and 0-2.0X10<-6>%RH<-1> (more preferably 0-1.5X 10<-6>%RH) difference between the max. value and min. value of the expansion coefft. with humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a magnetic recording flexible disk that can avoid tracking errors.

PRIOR ART Magnetic flexible disk recording/reproducing device It has been known for some time to prevent tracking errors by providing means for suppressing temperature changes in the magnetic flexible disk recording/reproducing device itself or by providing a special track detection circuit (trunk servo, etc.) in the recording/reproducing device. However, these methods require a complicated recording/reproducing device.

Therefore, in general, tracking errors can be avoided by improving the magnetic disk by changing the support film and magnetic material to materials with low coefficients of thermal expansion and humidity expansion, or by selectively engraving magnetic flexible disks. Prevention is being done.

However, even with improved type magnetic flexible disks, high temperatures (40 to 5 o ”c) @ high humidity (approximately 80%
If used in RH), a tracking error will occur. In particular, magnetic flexible disks recorded at low temperatures (r1o"cg degrees) and low humidity (20% RH, 8 degrees) will not track when played back at room temperature (about 25't) and normal humidity (about 60% RH). There is a drawback that a tracking error occurs.This tracking error causes a decrease in the output envelope and deteriorates the SIN ratio, which remains an unresolved problem.

Catalog of Inventions As a result of repeated research to eliminate the above-mentioned drawbacks, the present inventor has developed a method to adjust the temperature/humidity expansion coefficient of a biaxially oriented film made essentially of poly-p-7 enylene sulfide to a specific range. By doing this, a film with excellent dimensional stability was obtained, and by using this film as a support to manufacture a magnetic recording flexible disk, the occurrence of tracking errors could be avoided, and the present invention was achieved.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording flexible disk that expands the usable atmospheric conditions (temperature/humidity range) and is improved so that no tracking errors occur even at high temperatures and high humidity.

A magnetic recording flexible disk with high rc-i is capable of high-density magnetic recording, and it is an object of the present invention to provide such a magnetic disk.

Structure of the Invention The present invention is a magnetic disk using a 2t+* upward film as a support, in which 90 mol% or more of the magnetic disk is composed of poly-P-phenyl sulfide. The maximum coefficient of thermal expansion in a plane including the longitudinal direction and width direction of this film is 9 to 25X1
0'℃-1, maximum humidity i Zhang 4 is O~5,0XIO'%
RH”, the difference between the maximum and minimum coefficient of thermal expansion is 0 to 8.
The present invention provides a biaxially oriented poly-P-phenylene sulfide film having an expansion property of 0 to 2,0XIO'%RH-1 at OX 10°C and a difference between the maximum value and the minimum value of the humidity expansion coefficient. It serves as a support for the disc. The present invention is a magnetic recording flexible disk in which a magnetic layer is coated on this support and subjected to calender roll treatment to smooth the surface.

The poly-P-phenylene sulfide 2111 oriented film serving as the support for the magnetic disk of the present invention can be obtained by appropriately controlling the film forming conditions so as to satisfy the conditions of temperature and humidity expansion coefficient as described above.

The magnetic recording flexible disk of the present invention is composed of the support and a magnetic layer. The magnetic layer is made of magnetic powder or metal. The ferromagnetic powder and metal used in the present invention include r FetOs + Co-containing r
Fe20B, Fe504, Co-containing Fe3
O4, CrO2, Co-N1-P alloy, Co-Ni-F
Known ferromagnetic materials such as e-alloy, Co-Cr alloy, Co-Ni alloy, and barium ferrite can be used.

Examples of the binder used with the magnetic powder in the present invention include known thermoplastic resins, thermosetting resins, and mixtures thereof. Specifically, vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride typical polymer, vinyl chloride 7-acrylonitrile copolymer, acrylic acid ester acrylonitrile copolymer, acrylic acid ester vinylidene chloride copolymer, acrylic acid ester styrene copolymer, methacrylic acid ester acrylonitrile copolymer, methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer, Polyamide, polyvinyl vinyl, cell p
-S derivatives (cellulose acetate styrate, cellulose diacetate.

Cellulose triacetate, Cell 2m sprubionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin.

I: + Robinyl ether acrylic ester copolymer, amino resin, various synthetic rubber-based thermoplastic resins, mixtures thereof, etc. are used.

4 above onto the support film. ii The method for applying the magnetic layer is air doctor coating.

Blade coat, air knife coat, scissor coat,
Impregnation coat, reverse roll coat. Transfer roll coat, gravure coat, kiss coat, cast coat, misplay coat, etc. can be used.

A magnetic layer is coated on the support film to a thickness of 0.1 to 20 microns.

Poly P-phenylene sulfide, which is the support film in the present invention, has 90 mol% or more of structural units +@X
It is essential that the polymer consists of s+, and if it is less than 90 mol%, the crystallinity of the polymer will decrease and the coefficient of thermal expansion will increase, which is not preferable. If it is less than 10 mol% of the structural units of the polymer, it is not possible.

The general method for polymerizing such poly-P-phinidine sulfide is to react halobenzene with an alkali sulfide in a polar solvent.

As the polymerization conditions, a temperature of 250 to 350° C. is selected, and the polymerization time can be appropriately determined depending on the type of catalyst used and the pressure within the polymerization system and the degree of polymerization.

In the poly-P-phenylene sulfide film, there are, for example, anti-degradants, silicic acid silica.

A matting agent, lubricant, etc. such as kaolin, calcium carbonate, and calcium phosphate can also be contained or dispersed therein.

In the 24-oriented film made of poly P-7 enylene sulfide used in the present invention, the maximum thermal expansion coefficient in the plane including the longitudinal direction and width direction of the film is 9 to 2.
5 XIO''C', maximum wet elongation is O-5,0X
IO'%RH" (preferably 0-2,5X10'%RH
”).

The strain between the maximum and minimum temperature expansion coefficients is 0 to s, oxio
'℃'' (Good fL<hao ~5.0XIO-6℃l)
, the difference between the maximum and minimum humidity expansion coefficients is 0-5-2,0
XIO%RH (preferably o~1, s x 1o-6%
When the conditions of RH'') are satisfied, tracking errors can be avoided and the magnetic disk can be used in a wide range of temperature and humidity.

If the temperature expansion coefficient and/or humidity expansion coefficient exceeds the above range, the difference in temperature expansion coefficient and humidity expansion coefficient will cause the magnetic recording flexible disc to be The elongation from the center is different, and the magnetic head and the recording track are misaligned, often causing tracking errors. This results in output changes and dropouts.

Currently, polyethylene terephthalate-based polyester film, which is most commonly used for magnetic recording flexible disks, has a maximum thermal expansion coefficient of approximately 17X10.
°C ・The difference between the maximum and minimum coefficient of thermal expansion is 8 × 10-6
C.-1, and although the coefficient of thermal expansion is approximately the same as that of the recording/reproducing apparatus, there is a risk of track misalignment due to the directional difference in the coefficient of thermal expansion, that is, anisotropy. Also, the humidity expansion coefficient is approximately 11'X I
0%RHa degrees (, track deviation corresponding to humidity changes is quite large since the humidity expansion coefficient of the recording/reproducing apparatus can be regarded as 0).

On the other hand, by using the biaxially oriented film made of poly-P-phenylene sulfide of the present invention as a support, it is possible to achieve a higher temperature and humidity expansion track than the commonly used biaxially oriented film made of polyethylene terephthalate polyester. If the deviation is small and the difference between the maximum and minimum temperature expansion coefficients and the difference between the maximum and minimum humidity expansion coefficients are made small, the trunk deviation can be further suppressed. As a result, it is possible to obtain a magnetic recording flexible disk that can be used in a wide range of temperature and humidity in a wide range of temperature and humidity, and that can also perform high-density magnetic recording.

The poly P-phenylene sulfide film 'I 11 for obtaining the above-mentioned properties can be produced according to the method for producing polyester films such as polyethylene terephthalate and polybutylene terephthalate. For example, by the T-die method, inflation method, etc., depending on the melting point,
Melt extrusion at 350°C and unstretched film can be cast. Next, the film is stretched in two axial directions to form a biaxially oriented film.The stretching temperature at this time can be approximately the same temperature to a high temperature as in the case of polyethylene terephthalate film. The stretching temperature is preferably about 80-14.0"C. The stretching ratio is 3.0 to 5.0 times (preferably 3.5 to 4.518) in the machine direction and 3.0 to 5 in the section direction. .0
8 times (preferably 3.5 to 4.5 times). The obtained biaxially aligned film was heated at 150 to 280°C (preferably 1
By heat-setting the film at 80 to 270° C. for 1 to 100 seconds, a film with small displacement due to changes in temperature and humidity according to the present invention can be obtained.

However, the biaxially oriented film made of poly P-7 enylene sulfide of the present invention is not limited to that obtained by such a method. For example, by performing the above heat setting process twice with different running directions and making the second heat setting salinity higher than the first heat setting, the difference between the maximum and minimum values of the temperature expansion measurement can be minimized and the entire width of the film can be It can be held for a period of time.

The 2@lI oriented film can have an appropriate thickness depending on its use, and can usually be selected from a range of about 25 to 125 microns, but this range Kl is not limited.

The method for measuring characteristic values in the present invention is as follows.

il+ Temperature expansion coefficient Constant load elongation tester manufactured by Japan Automatic Control Co., Ltd. (ITL type 2) is placed in a constant temperature and humidity chamber and measured there.

Measurement samples are prepared under predetermined conditions (e.g. 70°C for 30 minutes)
Heat-treated the sample with
The temperature expansion coefficient is determined by taking the dimensional change between 40"C and 60% RH (relative humidity) and 40"C and 60% relative humidity.

The sample length at this time was 505 m and the sample width was 174 inches. The load applied during measurement is constant at 5 l (out of 174 inches). If a long sample cannot be obtained, measurement can be performed using a thermomechanical analyzer TM-3000 manufactured by Shinku Riko Co., Ltd. Maximum thermal expansion coefficient.

This method may be used to find the difference between the minimum values. The sample size is 15111. The width is 5 mm, and the difference between the maximum and minimum thermal expansion coefficients is determined by reading the dimensional changes at 20° C. and 0% RH humidity and at 40° C. and 0% RH humidity. Of course, the values obtained by both measuring instruments completely match.

(2) Humidity expansion coefficient As in the case of determining the temperature expansion coefficient, use a constant load elongation tester made by Japan Automatic Control Co., Ltd., and pre-process it under the conditions of 40°C and humidity 90% RH. The humidity expansion coefficient is determined by attaching a sample to a sample and reading the dimensional change between 20°C and 30% humidity and 20°C and 70% RH.

If the sample is short, a thermomechanical analyzer manufactured by Shinku Riko Co., Ltd. is placed in a constant temperature room machine and measured under the same conditions as in the case of thermal expansion measurement.

:3) Tracking deviation test (temperature change) The following method was used for the tracking deviation test. A magnetic recording flexible disk coated with a magnetic layer, calendered, and punched into a disk shape at 15℃ and humidity 60℃.
% RH, and check the maximum output at that time and the output envelope of the magnetic sheet. Maintain the ambient temperature at 40℃ and humidity 60%RH, measure the maximum output and output envelope at that temperature, and adjust the temperature to 15℃ and humidity 60%RH.
The output envelope at 40° C. and 60% RH is compared with the output envelope at 40° C. and 60% RH to determine whether tracking is good or not. The smaller this difference, the better the tracking! Possesses samurai characteristics.

If this difference is 3 dB or more, tracking is poor, and the evaluation is ``×'', and if it is within 3 dB, it is evaluated as ○.

(4) Tracking deviation test (humidity change) Recording was performed at 25°C and 20% RH in the same way as in the previous section, and the atmospheric conditions were further maintained at 25°C and 70% RH, and at 25°C and 20% RH.
The quality of tracking is evaluated in the same way as in the previous section by comparing the output envelopes when the temperature is 25° C. and 70% RH. The evaluation method is the same as in Section 3.

Example Next, the present invention will be specifically explained with reference to Examples.

Examples 1 to 4 and Comparative Examples 1 to 2 1 mol of Na2Sa 9Hρ, 0.05 mol of NaOH, 0.6 mol of sodium benzoate, and 3.5 mol of N-methylpyridone were placed in an autoclave and heated to 210°C. Dehydrated. After the dehydration was completed, the temperature of the system was lowered to 160°C, 1 mol of P-dichlorobenzene was added, and polymerization was carried out at 280°C with stirring. After the polymerization is completed, the temperature is lowered to room temperature and washed repeatedly with water and A7T. J-
A 13-phenylene fulfito polymer was obtained.

As a comparative example, the same procedure as in the example was carried out (except that 0.8 mol of P-dichlorobenzene was used instead of 1 mol of L, P-dichlorobenzef).
5 mol, using 0.15 mol of m-dichlorobenzene)
Polymerization was carried out at 280°C with stirring to obtain a copolymer of poly-P-phenylene sulfide and poly-m-7 dinilene sulfide.

Furthermore, as a comparative example, polyethylene terephthalate was polymerized by a conventional method.

These polymers were melt extruded at 300°C and 1050μ
An unstretched film was obtained.

Then 3.3 to 3.7 times in the longitudinal direction at 90 to 120°C.
Stretched 3.4 to 3.8 times in the transverse direction at 100 to 130°C,
Further, the mixture was fixed in a bottle at 200 to 270 DEG C. for 10 to 30 seconds to obtain a film having a thickness of 75 .mu.m and having different membranous properties. The biaxially oriented film thus obtained was coated with a magnetic coating liquid having the following composition to a thickness of 5 μm.

(Magnetic coating liquid) r-Fe, 0. 200 parts by weight Vinyl chloride-vinyl acetate copolymer resin 30 #
(UCC&!VAGH) Polyurethane 2o
(PP-as manufactured by Nippon Polyurethane Industries) Incyanate compound 4Qtt (Coronet manufactured by Nippon Polyurethane Industries) HL) Carbon (average size 0.5
μψ) 2o Dimethylsiloxane
2〃Toluene
70 〃Methyl ethyl ketone
70 Cyclohexanone
70 〃Mix and stir the above paint under sufficient pressure,
The poly-P-phenylene sulfide film was coated on the surface and then calendered. After this,
A magnetic recording flexible disk having an outer diameter of 2 ocIn and an inner diameter of 3.81 m was cut out and tested using a recording and reproducing apparatus.

The sheet recorder rotated at 3601'', p, m, and the magnetic head was positioned 8a from the center of the disk.The width of the track was 300μ, and the material of the head was ferrite.The magnetic recording flexible disk was equipped with an IMHz signal. was recorded under predetermined conditions, played back under predetermined conditions, and evaluated based on the difference in output envelope.

15℃, 60%R of this magnetic recording flexible disk
The envelope at 25°C and 20% RH is 0.
2 d13 or less.

Films made of poly-m-7 22lene sulfide under various film forming conditions were subjected to temperature/humidity expansion coefficient and trunk shift tests, and the results are shown in Table 1.

From the results in Table 1, it can be seen that tracking errors are improved in Examples 1 to 4, and the magnetic disks can be used in a high temperature and high humidity atmosphere. On the other hand, it was found that Comparative Examples 1 and 2 could not be used in a high temperature and high humidity atmosphere.

Effects of the Invention By applying a poly P-7 enylene sulfide biaxially oriented film having a specific temperature/humidity expansion coefficient to its support as an isk in magnetic recording, it is possible to obtain an isk without tracking errors. Furthermore, high-density recording is also possible by increasing the track density. Since the magnetic recording disk of the present invention has a small change in expansion coefficient due to temperature and humidity,
It has the advantage of being adaptable to moxibustion cases in a wide range of atmospheres.

Procedural Amendment Written by the Commissioner of the Japan Patent Office dated 8/9/1982 I Indication of the case Patent application No. 58 58744 No. 2 Name of the invention Magnetic recording flexible disk 3 Person making the amendment Relationship to the case Patent applicant Minami Higashi-ku, Osaka City 1-11 Honmachi (300) Teijin Limited Representative Sashibe Okamoto Subject (1) The scope of claims on page 1 of the specification is corrected as shown in the attached sheet.

(2) On page 3, line 6, it says “catalogue” and “purpose”.
Correct.

(3) On page 4, line 11 of the same page, replace “9-25” with “
Corrected to 9-35.

(4) On page 8, line 14, replace "9-25" with "
9-35 x 10°C, preferably 9-25''.

(5) The table on page 20 of the same page is corrected to the attached table.

Above 2, Claims: A magnetic recording disk comprising a plastic film as a support, a magnetic layer provided on the support, and a smooth surface, wherein the plastic film contains 90 mol% or more of polyp-
A biaxial internal film made of phenylene sulfide, which has a maximum temperature expansion coefficient of 9 to 35 x 10°C in a plane m1 including the longitudinal direction and width direction, and a maximum humidity expansion coefficient of 0 to 5. OX 10 ChiRH.

The difference between the maximum value and the minimum value of the coefficient of thermal expansion is O~8.0xio
℃ and the difference between the maximum and minimum humidity expansion coefficients is 0~
2. A magnetic recording flexible disk with a patent of OX 10% RH.

Claims (1)

[Claims] A plastic film is used as a support and magnetic j is applied to the support.
The problem is that in magnetic recording disks with smooth surfaces, the plastic film contains more than 90 mol% of poly-P.
- A biaxial internal film made of phenylene sulfide, which has a maximum temperature expansion coefficient of 9 to 25 x 10°C in a plane including the longitudinal direction and width direction, and a maximum humidity expansion coefficient of 0 to 5. Q X 10”+RE(
-1 The difference between the maximum and minimum temperature expansion coefficients is θ ~ 8.0X
IO'°C-1 and the difference between the maximum and minimum humidity expansion coefficients is 0 to 2. OX 10-6% RH'' magnetic recording flexible disk.