JPS608528B2 - How to use magnetic sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing a decrease in the output of a magnetic sheet used for high-density recording.

It has been known to use sheet-like and tape-like magnetic recording media.

Compared to tape-like materials (hereinafter referred to as magnetic tapes), sheet-like materials (hereinafter referred to as magnetic sheets) do not require rewinding or fast-winding the tape, and can quickly reproduce the recorded parts that you want to reproduce. This makes it suitable for cases where the operability of magnetic tape is a problem. You can use magnetic sheets to make recordings or mirror images,
A magnetic sheet recorder is used to perform this reproduction, and the magnetic sheet is rotated at high speed to levitate it in a horizontal state with no mirrors etc., and a magnetic head is slid on the magnetic layer to record and reproduce. was being carried out.

Next, the state of recording on a magnetic sheet will be explained using the attached diagram.

The mechanism for supporting the magnetic sheet of the magnetic sheet recorder includes a back plate, a magnetic sheet fixing means protruding upward from the central barrier hole 2 of the back plate, and a magnetic sheet fixing means provided below the back plate. It consists of a fixed motor 4, and a long hole 6 is bored in the back plate 1 to allow the magnetic head 5 to move freely and to approach the magnetic layer 7 of the magnetic sheet. The magnetic sheet fixing means includes a mounting punch 8 fixed to the motor shaft 3, a washer 9, and a screw 10 fixed to the protrusion of the mounting punch 8. The magnetic sheet is disk-shaped and consists of a magnetic layer 7 and a support 11, and a hole 12 for fixing it to a recorder is provided in the center of the disk. Since the thickness of the magnetic sheet is thin, when the hole 12 of the magnetic sheet is inserted into the mounting hole 8 of the recorder and the screw 10 is tightened as shown in the figure to fix it, the magnetic sheet is shown by the broken line in the figure. As shown, it is placed on the back plate 1.
When the motor 4 is activated, the magnetic sheet is given a specified direction and rotational speed, floats up due to centrifugal force while sliding against the back plate, and moves to a horizontal state as shown by the solid line. Thereafter, the magnetic head 5 projects upward from the long hole 6 of the back plate, approaches the magnetic layer 7 of the magnetic sheet, and performs necessary recording and reproduction. A magnetic sheet consists of a magnetic layer and a supporting base, and if necessary, a protective layer is provided on the surface of the magnetic layer, and an antistatic layer or a running stabilizing layer is also provided on the supporting base, if necessary. .

The shape of the magnetic sheet is usually donut-shaped, but if necessary, it can be used in an ellipse, rectangle, square, or other irregular shape. When used in a donut shape, the outer diameter is generally 10 to 50 mm, and the inner diameter is 3 to 5 ribs.The thickness of the magnetic layer of the magnetic sheet varies depending on the purpose, but is 0.05 mm. The thickness of the supporting substrate used for magnetic sheets is often 3 mm to 1 mm, depending on the application.
They range from extremely flexible to slightly elastic. The total thickness of the magnetic sheet is often 3 mm to 1 mm. Traditionally, needle-shaped y-Fe203 was mainly used as the magnetic material for magnetic sheets, but recently, the recording density has been increased and the sheet shape has been made smaller, and sheet recorders have also been made smaller and lighter. It's here. Along with this, there is a need to improve the characteristics of the magnetic material of the magnetic sheet as well. An effective method for this purpose is to increase the coercive force of the magnetic material used in the sheet. Therefore, conventional Y-Fe has a coercive force of 200 to 35
In place of 208, a magnetic material having a larger coercive force of 500 to 70 pi is now used. A magnetic material having such a coercive force is one whose main component is at least one or more of Fe, Co, and Ni reduced using ``1'' gas or NaB 4, Na2 2P02, and 20. Utilization of metal powder magnetic village.

{2} Utilizes plating film obtained by electrolytic or electroless lacquering method.

'3} A method that utilizes a ferromagnetic film obtained by vapor deposition or ion plating.

[4- y-Fe2Q, F containing or depositing Co
A method using e304, y-FeOX (1.33<x<1.5).

These are described in the following documents.

[1-Reference USP. Document No. 3843349, Japanese Patent Publication No. 49-130864 [2}
No. 19461, No. 49-41805 Glue literature USP. Specification No. 690589, Specification No. 384342 {41 Documents There are Tokusekki No. 49-119196, No. 49-120607, and No. 49-11319.

However, the manufacturing method of the magnetic materials obtained by the methods {1} to '3} is complicated, and the raw materials used tend to be expensive. As a result, the obtained magnetic material also became more expensive than conventional ones. In addition, the obtained properties had many variations, making it unsuitable for mass production. For this reason, the magnetic material shown in this paper came to be used as a magnetic sheet for high-density recording. The present inventors made a magnetic sheet using Co-containing iron oxide as the magnetic material of a magnetic sheet for high-density recording, and tested it with a sheet recorder, and obtained the following results.

In other words, with magnetic sheets made of these magnetic materials, even if the playback output immediately after recording is sufficiently high and the video sensitivity, output envelope, etc. are satisfactory, the output of the sheet will increase if used continuously for a long time. It was found to decrease during

This phenomenon will be explained in detail below. If you make a magnetic sheet using cobalt-added iron oxide as a nourishing material, set it in a sheet recorder, record the signal, and continue to play it continuously,
After 5 feeding hours, a decrease in output of about 2 to phantom B compared to the initial output was observed, and after 10 feeding hours, a decrease of about 5 to 1 Q old was observed.

To confirm, I demagnetized and rerecorded the continuously played sheet, but the output was the same as the tape I recorded it on for the first time. Of course, during such long-term continuous playback, no scraping of the magnetic layer of the magnetic sheet or head adhesion occurred. Therefore, it was considered that the cause of such a decrease in output was due to regenerative demagnetization of the magnetic material itself. Recently, Co
Some types of added iron oxide magnetic material (Co-coated y-Fe○
×, 1.33 < x < 1.5) has little demagnetization and can be used for tapes, but it was found that it cannot be used for magnetic sheets that are run many times.

In other words, it has become an important problem to improve the decrease in output during repeated reproduction when a Co-doped iron oxide magnetic film is used as a magnetic sheet in producing a high recording density sheet. In order to solve this problem, the present inventors conducted various studies and as a result, the present invention was accomplished through the following process. When using a magnetic sheet, recording and reproducing have conventionally been carried out by devising a head shape in order to extend the life of the sheet.

In this case, since the magnetic material for the magnetic sheet was y-Fe203, there was no need to consider the deterioration of the sheet itself, and it was only necessary to devise ways to make the head touch smoothly with the sheet. That is, heads for sheets may be in contact with the sheet or non-contact, and the coefficient of friction between the sheet and the head has not been considered at all. The inventors of the present invention conducted tests focusing on this point and discovered a surprising fact. In other words, it was found that in a magnetic sheet using Co-added iron oxide magnetic material, if the coefficient of friction acting between the sheet and the head is 0.4 or less, the output decreases by 4. .
The reason why this effect is unique to the Co-added iron oxide enrichment sheet is as follows. That is, y-Fe
The crystal structure of 203 is composed of Fe and ○, and it has an extremely stable shape, so it is stable against external influences such as pressurization and heating. However, in the case of Co-added iron oxide, Fe and ○ Due to the introduction of Co into the crystal structure of the magnetic head, the crystal structure is partially changed and becomes unstable under pressure and heat. This occurs when the magnetic sheet comes into contact with the magnetic sheet due to its high speed rotation, so reducing the friction at the time of contact can prevent shelving.As for the conditions for using the sheet, the relative speed between the head and the sheet is In practice, it was effective without any problems at 60 units/sec or less, and any shape of the head was effective.

As for the cause of this, the present inventors found that the number of repeated contacts between the magnetic sheet and the head is significantly larger than that of magnetic tape.
While we investigated tape demagnetization when running 500 times to 10 million times, we investigated sheet demagnetization when running 5 to 10 million times, so there was a difference between the results and the tape, and when used under these conditions. It is estimated that the recording of the Co iron oxide magnetic material will be demagnetized when the sheet and the head come into contact unless the sheet is used in a state of smoother contact than with tape. That is, the present invention aims to reduce the coefficient of friction between the magnetic sheet and the magnetic head to 0.4 or less when recording and reproducing by setting a magnetic sheet made of cobalt-containing iron oxide as a magnetic material in a sheet recorder. The present invention relates to a method of using a magnetic sheet characterized by:

In the method of the present invention, in order to reduce the coefficient of friction between the magnetic sheet and the magnetic head to 0.4 or less, a magnetic sheet with a lubricant present on at least the surface portion of the magnetic layer is used, and the magnetic sheet Therefore, it is necessary to use a Mn-Zn ferrite head. The magnetic materials used in the present invention include y-Fe203, Fe304, y-Feok (1.3
3<x<1.5) or a mixture of several kinds.
203, Fe304, chromium dioxide, Fe, Co, Nj
It is also possible to use it by mixing it with an alloy powder whose main component is

Furthermore, if necessary, the magnetic layer may not be uniformly dispersed, but may be multilayered, with a Co-doped oxide magnetic layer on the top layer and a Y-coated oxide magnetic layer on the bottom layer.
Various combinations such as Fe203 layer or the reverse layer arrangement are also possible. There are two methods for adding Co: a wet method and a dry method. The wet method is a method in which Co is co-precipitated when making acicular iron oxyhydroxide such as goethite, and the dry method is a method in which Co is co-precipitated when making acicular iron oxyhydroxide such as goethite. Iron hydroxide, Fe304, y-
C as a dry powder of Fe○x,y-Fe203
This is a method of coating o from the outside and heating and diffusing it.

Note that the amount of Co added may be about 0 to 2% by weight based on the iron oxide. The relative speed between the magnetic sheet and the magnetic head is 60 skin/
It is effective if the speed is less than 50 m/s, but preferably less than 50 m/s.

The coefficient of friction between the sheet and the head is 0.4 or less, preferably 0.2 or less. Here, Mn--Zn ferrite is used as the material for the recording/reproducing head. In order to reduce the coefficient of friction, for example, a lubricant can be sprayed onto a sheet or head. Examples of lubricants include dimethylpolysiloxane, amyl stearate, oleic acid, alkyl amine phosphorus, dialkyl sulfosuccine. -g, lipophilic polyester, quaternary ammonium salt,
Naphthalene sulfonic acid condensate, polyoxy ethylene alkyl amide, polyoxy ethylene alkyl amine,
Polyethylene glycol oleyl ether, polyethylene glycol ester, bisnaphthalene sulfonate,
Examples include alkylphenol polyethylene ether, polyoxyethylene alkylphenol ether, 8-naphthalenesulfonic acid sodium condensate, and laurylic acid alcohol sulfate ester sodium salt. In addition to the spray method, the above lubricant can be added to the binder of the magnetic coating solution described below at a ratio of 0.001 to 5% by weight relative to the binder, or the lubricant can be added to the binder of the magnetic coating solution after applying the magnetic coating solution. It can be incorporated into the magnetic layer by coating the surface of the sheet with a thickness of two peaks or less.

In any case, the lubricant should be present on at least the surface portion of the magnetic layer. As the binder used in the magnetic sheet of the present invention, conventionally known thermoplastic resins, thermosetting resins, reactive resins, and mixtures thereof are used.

The thermoplastic resin has a softening temperature of 150°C or less, an average molecular weight of 10,000 to 200,000, and a degree of polymerization of about 200 to 200.
50 degrees Fahrenheit, such as vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonitrile copolymer, acrylic acid ester acrylonitrile copolymer, acrylic acid ester vinylidene chloride copolymer, Styrene ester acrylate copolymer, ester methacrylate acrylonitrile copolymer, ester methacrylate vinyl chloride IJ dene copolymer, ester styrene methacrylate copolymer, urethane elastomer,
Polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (
Cellulose acetate monophthalate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitro. (cellulose, etc.), styrene-butadiene copolymers, polyester resins, chlorovinyl ether acrylate copolymers, amino resins, various synthetic rubber-based thermoplastic resins, and mixtures thereof. Examples of these resins include Japanese Patent Publications No. 37-6877, No. 39-12528, No. 39-19282, No. 4
0-534 number, 40-20907, 41-94
No. 63, No. 41-14059, No. 41-16985, No. 42-6428, No. 42-11621, No. 43
-4623, 43-15206, 44-288
No. 44-17947, No. 44-18232, No. 45-1402, No. 45-14500, No. 47
-18573, 47-22063, 47-22
No. 064, No. 47-22068, No. 47-22069
No. 47-22070, No. 47-27886, etc. As a thermosetting resin or a reactive resin, it has a molecular weight of 2×1 or less in the state of a coating liquid,
By heating after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. Also, among these resins, those that do not soften or melt before the resin is thermally decomposed are preferred. Specifically, for example, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, silicone resin, acrylic reaction resin, epoxy-polyamide resin, and nitride resin. Cellulose melamine resin, mixture of polymeric polyester resin and isocyanate prepolymer, mixture of methacrylate copolymer and diisocyanate prepolymer, mixture of polyester polyol and polyisocyanate, urea formaldehyde resin, low molecular weight glycol/high Mixtures of molecular diols/triphenylmethane triisocyanates, polyamine resins and mixtures thereof. Examples of these resins are given in Japanese Patent Publication Nos. 39-18103 and 40-97.
7 number "No. 41-7192 No. 41-8016"
No. 41-14275, No. 42-1817, No. 4
No. 3-12081, No. 44-28023, No. 45-1
No. 4501, No. 45-24902, No. 46-1310
No. 3, No. 47-22065, No. 47-22066,
No. 47-22067, No. 47-22072, No. 47
-22073, 47-28045, 47-28
It is described in publications such as No. 048 and No. 47-28922. These binders may be used alone or in combination, and other additives may be added.

The mixing ratio of the ferromagnetic powder and the binder is within the range of 10 to 20 parts by weight of the binder to 10 parts by weight of the ferromagnetic powder. Additives include dispersants, lubricants, abrasives, etc. Materials for the support used in the magnetic sheet of the present invention include commonly used polyesters such as polyethylene terephthalate and polyethylene-2.6 naphthalate, polyethylene, Polyolefins such as polypropylene, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate.

Cellulose derivatives such as lopionate, polyvinyl chloride,
In addition to vinyl resins such as polyvinylidene chloride, plastics such as polycarbonate, polyimide, and polyamideimide, non-magnetic metals such as aluminum and copper, depending on the application,
Paper, baryta, or paper coated with or laminated with Q-polyolefin having 2 to 10 carbon atoms such as polyethylene, polypropylene, or ethylene-butene copolymer can also be used. These supports may be transparent or opaque depending on the intended use of the magnetic recording medium. The following method is available as a method for dispersing these magnetic materials and a binder together with a solvent and then providing them on a support.

The method for coating the magnetic recording layer on the support is as follows:
Air Doctor Coat "Plaid Coat, Air Knife Coat, Squeeze Coat, Deep Coat, Reverse Roll Coat, Transfer Roll Coat, Gravure Coat, Kiss Coat, Cast Coat" Spray coating methods can be used, and other methods are also possible. A detailed explanation is given in "Coating Engineering" 253 published by Asakura Shoten.
It is described in detail on pages 27 to 27 (Takayuki Sotsu, March 2, 1971).

The method of using the present invention applies both to sheet recorders where the head and sheet are in constant contact, and sheet recorders where the head and sheet are in contact when the recorder starts or stops, but are non-contact during steady rotation. , can be applied together.

By employing the method of the present invention, the following effects can be achieved.

1. Creating a magnetic sheet capable of high-density recording.

2. To create a magnetic sheet that has less output drop when used repeatedly.

3. To create a magnetic sheet with a long sheet life.

4. Creating a seat with less fluctuation in output during one lap.

5. By applying lubricant to the entire surface or part of the recorder head in contact with the sheet, it lowers the coefficient of friction between the sheet and the head, and prevents a decrease in the output of the magnetic tape used. ``Extends the life of the magnetic tape, reduces output fluctuations during one rotation, etc.'' effect can be obtained.

It was a success. Example 1 On a polyethylene terephthalate base having a thickness of 22 cm, coating liquid A having the composition shown below was applied to a thickness of 6 mounds.

The magnetic material used was y-Fe20 containing 2.8% Co.
It is 3. The coercive force is 55, and its size is 0.02
◇It was Buddha x 0.14 Buddha. Calendar treatment after application.
A test was conducted by cutting out a sheet with an outer diameter of 14 arcs and an inner diameter of 12 ribs. The recorder I used had a speed of 360pm and was set at a position 6 degrees from the center of the head G. The head is Mn-
A Zn-based ferrite head with a diameter of 500 mm and a length of 2 legs with the tip and rear ends rounded. In order to change the coefficient of friction between the sheet and the head, a lubricant (dimethyl polysiloxane) was sprayed onto the doughnut-shaped sheet. The friction coefficient was controlled by the spraying time (see notes in Table 1). The measurement results are shown in Table 1, 1003-1006. For comparison, the material in the coating composition was Co-containing y-Fe203 to y-F.
The results of the sheet changed to e203 are also shown in 1001-1002. Coating composition A ・Magnetic material (Co-containing y-Fe203) ...30
Nitrocellulose (nitrogen content 11.2%, degree of polymerization 550) 21 polyvinyl chloride-pinylidene chloride copolymer (copolymerization ratio = 7:3, degree of polymerization = 400)
...8 evening.

Epoxy resin (reaction product of bisphenol A and epichlorohydrin, molecular weight: 900, epoxy equivalent = 460
~520, hydroxyl group content = 0.29%, ShellOi
lCo. The product name is Epicort 1001)...・14
evening.

Silicone oil (dimethylpolysiloxane)...0
．． 8.Soybean lecithin...
1.2 hours/Alumina oxide (average particle size: 4)
...8 polycarbon black (average particle size 2 French) ...20 Isocyanate compound (reaction product of 3 moles of 2,4-lylene diisocyanate compound and 1 mole of trimethylolpropane) 7
5% by weight ethyl acetate solution manufactured by Bayer, trade name: Des
modurL-75) ・・
...1.4 evening.

Butyl acetate...1200 ta Example 2 Coating liquid B having the following composition was applied to a thickness of 6 mounds on a polyethylene terephthalate base having a thickness of 36 mm.

The magnetic material used was a magnetic material in which Co was deposited on Fe0x (x=1.42) at a rate of 1.8%. Its coercive force is 58 ×, and its size is 0.02? It was #×0.14 Buddha. Sheet shape t The recorder head and the like were measured in the same manner as in Example 1. 2001 and 200 as comparative examples
2 shows the results of using the materials 1001 and loo2 of Example 1 in coating liquid B. The results are shown in Table 2. The method for reducing the coefficient of friction was the same as in Example 1. Coating liquid composition B - Magnetic material [Col. 8% treated Fe○× (x=1.42)
]...4.300 evening.

Vinyl chloride vinylidene chloride copolymer (copolymerization ratio = 733
"Polymerization degree: 400)...b24 Epoxy resin (reaction product of bisphenol A and epichlorohydrin" Molecular weight = 900 ~ Epoxy equivalent = 460 ~ 520 "Hydroxyl group content = 0.29% Epicort 1001 (product name of Shell Oil Co.)...18th evening.

Silicone example (dimethylpolysiloxane)...1
．． 2 days ago・Chromium oxide (Cr203, average particle size 5 degrees)・….

・10 evening. Isocyanate compound (Desmod mL-75 from yerA.G., 75% by weight ethyl acetate solution of the reaction product of 3 moles of 2,4-tolylene diisocyanate compound and 1 mole of trimethylolpropane).・・・．・
・2.4 evening・Butyl acetate...
Example 3 Amyl stearate was applied to the head surface of the recorder of Example 1, and No. 1 of Example 1 was applied. 1
3004 and 3005 in Table 3 show the results of measuring the sheet life using No. 003 sheet without spray treatment.

In addition, 3003 shows the results when both the head and the sheet are not spray treated (that is, the same as 1003) as a comparative example. (18,1 le temple l!'h sword low-C after the stroke: 4MI
Record the signal of 1z on the point 48. (184) Compare the decrease in external force after the time with the output at the start.

Sheet life: Using the same method as above, the output was set to 3 dU1. Yamariki's En-Kurobe: Record the 4MHz signal on a sheet. Maximum mountain force waveform in one rotation. Find the smallest ratio. The small left side is an excellent seat. Edge coefficient: Het material (Mn-Zn): [Light], head 1l1500''. Set the hetto long 2 ribs (described in Example 1) to the shi-1 record-k. Multiply the head by 10y and 16. Seat rotation speed 3
As 60 rpm. At that time, the magnitude of the running resistance applied to the head is X ter (in some cases, X/10 is the coefficient of friction) [The following was confirmed from the above Examples and Comparative Examples.

A sheet using ly-Fe203 as a nutritious material has little reduction in output regardless of the friction coefficient. 2 In a sheet using Co-added iron oxide as a magnetic material, when the friction coefficient between the sheet and the head is 0.4 or less, the reproduction output decreases little.

3 Particularly in item 2, if the friction coefficient is 0.2 or less, it is even smaller.

4 These results are true regardless of the type of Co-containing iron oxide magnetic material.

[Brief explanation of the drawing]

The attached figure shows the state in which a magnetic sheet is set in a magnetic sheet recorder and recorded.

Claims (1)

[Claims] 1. When a magnetic sheet using cobalt-containing iron oxide as a magnetic material is set in a sheet recorder for recording and reproduction, a lubricant is present on at least the surface portion of the magnetic layer of the magnetic sheet, and the sheet is used as a magnetic head. A method of using a magnetic sheet, characterized in that the coefficient of friction between the magnetic sheet and the magnetic head is set to 0.4 or less using a Mn--Zn ferrite head.