JPS60133540A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having high smoothness by immersing a base plate consisting of a high polymer molding into a solvent which dissolves the oligomer cintained in the base plate then taking out the base plate, subjecting the same to a heating treatment below the melting and decomposing temp. and cleaning away the oligomer depositing on the surface. CONSTITUTION:A base plate 41 consisting of a high polymer molding such as a polyethylene terephthalate film or the like is immersed in a solvent which can dissolve the oligomer contained therein, by which the base plate is precleaned. For example, a polyetheylene terephthalate base plate (abbreviated as PET) is immersed in acetone and oligomer is removed by prewashing and thereafter the base plate is kept put in a thermostatic chamber for about 1hr at 180 deg.C to deposite the internal oligomer. The base plate is then cleaned again by the acetone to dissolve the oligomer away. The base plate is cleaned with alcohol to remove the acetone and thereafter gaseous N2 is blown thereto to remove the alchol. A magnetic layer is coated or deposited by vacuum evaporation on such base body. Not only the deposition of the oligomer by the effect of heat during formation of the magnetic layer but also the deposition after production are thus obviated by two stages of oligomer removal. The smooth magnetic recording medium having an excellent electromagnetic converting characteristic and durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for treating a polymer molded substrate, which is a base of a magnetic recording medium.

[Prior art]

As a magnetic recording medium using a polymer molded substrate, r
-Fe203. co%I r-F e203'+metal, C! Coating methods such as v02 are the mainstream, and are used on the other side of floppies, audio tapes, video tapes, data files, document files, and memory for audio and image processing. In addition, in contrast to such wet coating, dry vacuum evaporation is used to coat 00 and Co.
Audio tapes, yawn video tapes, etc. formed with -Ni are beginning to be commercially available. The technological trends that are common to both digital and analog recording are as follows:
For computer files, compaction or Otani vaporization is used, as well as audio formatting.

For videotapes, efforts are being made to improve the quality of 1IiIII or i. In other words, in order to achieve a high S/N, it is desirable to improve the media's strength and make the thickness of the medium uniform, and to achieve high s/N, it is desirable to reduce the thickness of the media in the future for magnetic recording media. On the other hand, polyethylene terephthalate (1) is mainly used as a substrate for such magnetic recording media due to its low cost and mechanical strength.
A film (hereinafter abbreviated as PIT) is used. Recently, aramid films have also begun to be considered because they have good surface properties and mechanical properties that are superior to PET.

In any case, these polymer molded substrates contain unreacted monomers (monomers) and polymers with low Jiζ degree (hereinafter referred to as oligomers), so the glass transition temperature ] For example, PIT has a glass transition at about 70°C.) If the position is more than that, oligomers will precipitate on the substrate surface (1), and the Table 1 El property of the substrate will be significantly deteriorated. Specifically, the height of this oligomer is
Depending on storage and retention time, the size ranges from 0.2 microns to several microns.

As described above, when a molded polymer substrate is used as a substrate for a magnetic recording medium, a humidity environment exceeding the glass transition occurs during the process of forming a magnetic film (specifically, in wet coating, magnetic In hot air drying after body coating, and in dry vacuum evaporation, oligomers are deposited on the surface of the polymer molded substrate due to heat radiation from the N film forming source during evaporation, and the coating medium is affected by thickness unevenness. Noise generation: In vacuum evaporation, the surface quality of the substrate becomes the surface quality after forming the thin film, which worsens the contact between the medium and the head.
Recording and reproducing efficiency decreases. Furthermore, the protrusions on the surface of the medium are
There is a problem in that collision with the head causes peeling of the film and deteriorates the durability of both the medium and the head.

Conventionally, in order to eliminate bare-surface protrusions caused by oligomer precipitation after forming one layer, the protrusions were polished by lapping or puff polishing to improve the smoothness of the film, but this only impairs the continuity of the film or causes wear. Add more IM 1M1 with powder
It had the disadvantage of attaching fi:tM. Furthermore, as described above, as magnetic recording media become more compact and have larger capacities, and the thickness of the media becomes thinner, the problems caused by the protrusions caused by oligomer precipitation have become even more serious.

Therefore, before coating, drying, vapor deposition, etc. on the polymer molded substrate, the polymer molded substrate is heat-treated at a temperature below the melting, sublimation, or decomposition temperature of the substrate, and the oligomers precipitated on the front decoy substrate are removed with a solvent. After cleaning, a magnetic layer is formed to create a magnetic recording medium with very little unevenness. However, on the substrate where this oligomer was cleaned with common chemicals,
Traces of oligomer precipitation were formed, and although the protrusions caused by the oligomers disappeared, the number of depressions caused by the precipitation traces increased.

Note that this oligomer is not only unavoidable in the manufacturing process for manufacturing a polymer molded substrate, but also intentionally kept in a rare amount in order to provide stretchability when processing into a film.

〔the purpose〕

In view of the above points, the present invention provides a method for forming a magnetic recording medium 1j11.
Another object of this invention is to remove oligomers contained in the polymer molded substrate that serves as the base of the medium, and to produce a 4-acupuncture recording medium with excellent smoothness, electromagnetic conversion characteristics, and durability.

〔overview〕

In the present invention, only the oligomers contained in the polymer molded substrate, which is the base of the longitudinal magnetic recording medium, are dissolved using an organic compound, and then the remaining oligomers in the molecular molded substrate are forcibly precipitated by heat treatment, and then The present invention aims to produce a highly smooth magnetic recording medium by forming a magnetic layer on a polymer molded substrate from which oligomers have been removed using the 1a solvent or other methods.

〔Example〕

The present invention will be explained in detail using figures.

Implementation 1/ll 1 As this implementation 1+lJ, PET (
Polyethylene terephthalate) was used, and acetone was used as the extraction agent. Other extractants such as trichlene and xylene may also be used. FIG. 1 is a flowchart of the process for creating the media of the present invention. First, PET is immersed in acetone, then the PET is placed in a constant temperature bath at 180°C for 1 hour to precipitate the remaining oligomers, and the PIlXT'
? i: Soak in acetone, then soak in alcohol to remove the evaporated residue of a7ton on PICT, then PBT
Spray the remaining alcohol on the top and blow it away with the paste,
The coating process or vacuum deposition process has started. Figure 2 (・)
is a surface cross-sectional view of pm'r according to the present invention. On the other hand, before the conventional method of oligomer precipitation, the substrate was treated with an organic cleaning agent l1.
In the case where lIj is not applied, traces of oligomer precipitation remain on the substrate surface as shown in FIG. 2 (/+). The hole through which the oligomer is extracted can be as large as 1 micron in depth and several millimeters wide, depending on the location.

1 J 1-j: ノ Jujl & S 2 γ-F e203 PBT is used as the substrate of the coating medium, and it is called a floppy disk.
There is. The conventional floppy path is shown in Figure 3(b). A 1-21'e203 magnetic recording layer 64 is coated on the PIT 33, and a process of orientation, drying, and surface polishing is performed.In particular, since hot air drying is used for drying, the PIT33 is coated with a 1-21'e203 magnetic recording layer 64.
Oligomer 65 is precipitated around KT33i. FIG. 3 (α) shows the pH after the oligomer treatment according to the present invention! T
After 31, γ-Fθ20. @Ki recording layer 3
This is the structure of a floppy disk that has undergone the steps of coating No. 2, orientation treatment, drying, and surface polishing. According to the invention, P.E.
It can be seen that no oligomer is precipitated on the T surface. In the conventional type 70T, the magnetic layer thickness is uneven due to oligomer precipitation, which causes media noise, and the S/N ratio is 5.
On the other hand, in the floppy disk using the oligomer-treated PET of the present invention, the /N ratio was 35, dB or more because the magnetic layer thickness was uniform.

Implementation Reli 3 Using continuous winding steam and director equipment, C0-N is applied to PET.
I made fish scraps. A so-called steamed J tape was produced. According to the conventional method, oligomers are precipitated between the PET surfaces by the radiation #I from the evaporation source, and while being scattered in the vacuum, 0o-
-Ni is deposited. Naturally, the degree of vacuum during vapor deposition deteriorated, and good quality Co--Ni was not formed. A cross-sectional view of the vapor deposition tape is shown in FIG. 4(h). Unlike coating, vacuum evaporation is characterized by the formation of an iH film on the surface of the substrate. 43
PET 144 is a Co-Ni layer, and 45 is an oligomer. Next, PET treated with the present invention has no oligomers as shown in Figure 4 (a). No. 41 is PET treated with oligomers, and No. 42 is Co-Ni. Conventional fish waste tape The envelopes of the vapor-deposited tapes according to the present invention are compared in FIGS. 5(b) and (α), respectively.
It is. Conventional vapor layered tapes have low playback output and high frequency noise due to head hits due to carving of media protrusions by oligomers, whereas L'V4f according to the present invention
--yc.The reproduction output is also large and the noise is small. Also,
The present invention also has a great effect on the durability of the media.
Whereas the conventional vapor deposition medium easily generates heat and requires removal of protrusions caused by oligomers during one-buff testing, the vapor deposition medium and one-puff polishing according to the present invention does not cause concerns. Yes, it has the effect of reducing durability and A. -1-
1. [Effects] As described above, the magnetic recording medium according to the present invention has various effects compared to the conventional method. The effects are summarized below.

0 Improved playback output 0 Decreased noise 0 Improved envelope 0 Reduced media defects 0 Improved magnetic properties 0 Improved durability Furthermore, when using a vacuum like vapor deposition tape temple, set PET inside the vacuum shaft Since the oligomer is treated before the process, the true roughness will be the same, and the time required to reach a predetermined vacuum level will be shortened, resulting in cost reduction. It also has the effect of drastically reducing dirt inside the vacuum chamber.

In addition, in this implementation report, PET is used as a polymer molded substrate.
We used aramid, polyether sulfon, vinyl chloride, polystyrene, silica carbonate, polypropylene, triacetate, polyether ether ketone, polysulfon, etc. Acrylic resin, which is the base material of engineering cooler illuminance, light, and +W air recording material. The present invention is also effective in such cases.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of the steps for producing the medium of the present invention. Figure 2 is a cross-sectional view of the i-plane (P, KT+7), (α)
is according to the present invention, and (b) is conventional U''. Third
The figure is a sectional view of the surface portion of a coated magnetic recording medium. (a)
(b) is the case where the substrate was processed according to the present invention, and (b) is the case where the substrate was not processed in the conventional manner. FIG. 4 is a sectional view of the surface of the yA fitting. (α) is a sectional view of a vapor deposition tape according to the present invention, and (b) is a sectional view of a conventional vapor deposition tape. FIG. 5 shows an envelope using vapor-deposited tape. (α) is the envelope of the vapor-deposited tape produced using the present invention, and (b) is the envelope of the conventional vapor-deposited tape. 21 ... ... PET 22 ... ... ... PE'l'31 ...
・・・・・・・PE T32・・・・・・r-re
20. Magnetic recording layer 36... PFiT 64... γ-Fθ203 Magnetic recording layer 35...
...Oligomer 41 ...PKT 42 ...Oo-N i layer 43 ...PET 44 ...OO-N i layer 45 ... ...Oligomers and above Applicant: Suwa Seiko Co., Ltd. Patent Attorney Patent Attorney Mogami Figure 1 (α) (1) Figure 2 (K) Figure 3

Claims (1)

[Claims] In a longitudinal magnetic recording medium in which the magnetization component is mainly parallel to the magnetic recording surface, after immersing the polymer molded substrate, which is the base of the medium, in an organic activator that dissolves the oligonyls contained in the substrate,
Polymer molded substrates heat-treated at a temperature below the bath melting, sublimation, or decomposition temperature of the substrates Table 1
1. A method for producing a magnetic recording medium, which comprises forming a magnetic layer on a polymer molded substrate in which oligomers precipitated on a thin film are thinned.