JPS5840252B2 - Zixito - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic sheet with improved properties.

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. It is suitable for cases where the operability of magnetic tape is an issue.

A magnetic sheet recorder is used to perform recording or recording using a magnetic sheet, and it is used to rotate the magnetic sheet at high speed and keep it in a horizontal state without bending. Recording and reproducing was performed by floating the magnetic head on the magnetic layer and bringing the magnetic head into sliding contact with the magnetic layer.

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

The mechanism for supporting the magnetic sheet of the magnetic sheet recorder includes a back plate 1, magnetic sheet fixing means protruding upward from the central opening 2 of the back plate, and a mechanism provided below the back plate 1, with the magnetic sheet fixing means attached to the shaft 3. It consists of a fixed motor 4, and a long hole 6 is bored in the back plate 1 so that the magnetic head 5 can slide freely and approach the magnetic layer 7 of the magnetic sheet.

The magnetic sheet fixing means includes a mounting rod 8 fixed to the motor shaft 3, a washer 9, and a screw 1 fixed to a protrusion of the mounting rod 8.
Consists of 0.

The magnetic sheet is in the shape of a disk, and a hole 12 is provided in the center of the disk for removing it from the magnetic layer 7 and support 11 and fixing it to a recorder.

Since the thickness of the magnetic sheet is thin, the holes 12 in the magnetic sheet
into the recorder's mounting rod 8, and tighten the screw 10 as shown in the figure.
When the magnetic sheet is tightened and fixed, the magnetic sheet is bent on the back plate 1 as shown by the broken line in FIG.

When the motor 4 is started, the magnetic sheet is given a prescribed direction and rotational speed, and floats up due to centrifugal force while sliding against the back plate, shifting to a horizontal state as shown by the solid line.

Thereafter, the magnetic head 5 projects upward from the elongated hole 6 of the back plate 1 and approaches the magnetic layer 7 of the magnetic sheet, thereby performing necessary recording and reproduction.

The magnetic sheet used in these magnetic sheet recorders has the following structure.

A magnetic sheet consists of at least a magnetic layer and a support, and if necessary, a protective layer is provided on the surface of the magnetic layer and a back layer is provided on one of the supports.

The magnetic layer can be formed by directly providing one or more of Fe, Co, Ni, etc. by plating, vapor deposition, sputtering, ion blating, etc., or by dispersing powder or magnetic material in a binder and applying it. be.

The following magnetic materials, supports, binders, and coating methods have been commonly used in these magnetic sheets.

As the ferromagnetic powder, γ-Fe 203 is used. Co-containing γ-Fe203, Fe3O4, Co-containing Fe3
O4, CrO2, Co-N1-P alloy, Fe-C.

-Ni alloy and other known ferromagnetic fine powders can be used, specifically, Japanese Patent Publications No. 44-14090, Japanese Patent Publication No. 45-1
8372 Publication, Japanese Patent Publication No. 47-22062, Japanese Patent Publication No. 47-22513, Japanese Patent Publication No. 46-28466, Japanese Patent Publication No. 46-38755, Japanese Patent Publication No. 47-4
They are described in Japanese Patent Publication No. 286, Japanese Patent Publication No. 47-12422, Japanese Patent Publication No. 17284-1984, Japanese Patent Publication No. 18509-1987, Japanese Patent Publication No. 4718573, etc.

As the binder, 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 and an average molecular weight of 10,000 to 200,000. Degree of polymerization is about 200~
500, such as vinyl chloride-vinylidene acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer Coalescence, acrylic ester-styrene copolymer, methacrylic ester-acrylonitrile copolymer, methacrylic ester-vinylidene chloride copolymer, methacrylic ester-styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride Acrylonitrile copolymer, butadiene-acrylonitrile copolymer, Boriato resin, polyvinyl butyral, cellulose derivative (cellulose acetate butyrate, ce/I/O-stiacetate, cellulose triacetate, cellulose propionate, cellulose nice) Styrene-butadiene copolymers, polyester resins, chlorovinyl ether acrylic acid ester copolymers, ano resins, various synthetic rubber-based thermoplastic resins, and mixtures thereof are used. Ru.

To form the magnetic recording layer, the above-mentioned composition is dissolved in an organic solvent and applied as a coating solution onto a support.

Examples of these resins are given in Japanese Patent Publication No. 37-6877, 39-
No. 12528, 39-192.82 million, 40-53.49 million, 40-209.07 million, 41-9463 Takumi, 41-14
No. 059, No. 41-16985, No. 42-6428, 4
2-116.21 million, 43-4623 Takumi, 43-1520
No. 6, No. 44-2889, No. 44-17947, 44-
No. 18232, No. 45-14020, No. 45-14500
10,000, 47-185,730,000, 47-22063, 47-
It is described in publications such as No. 22064, No. 4722068, No. 47-22069, No. 47-22070, and No. 47-27886.

Thermosetting resin or reactive resin is 2X1 in the coating liquid state.
It has a molecular weight of 0.05 or less, and when heated 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 during thermal decomposition of the resin 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, nitrocellulose melamine resin, polymer polyester resin and isocyanate prepolymers, mixtures of methacrylic acid base copolymers and diisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanates, boria□ resins and mixtures thereof.

Examples of these resins are given in Japanese Patent Publication No. 39-8103, 40-
No. 9779, 41-71.92 million, 41-801675.
No. 4114275, No. 42-18179, 431208
No. 1, No. 44-28023, No. 45-14501, 45
-24902, 46-131,030,000, 47-2206
5'75.47-22066, 47-22067, 47-22072, 47-22073, 4728
It is described in publications such as No. 0.45 million, No. 47-280.46 million, and No. 4728922.

These binders may be used alone or in combination;
Other additives may be added.

The mixing ratio of the ferromagnetic powder and the binder is in the range of 10 to 200 parts by weight per 100 parts by weight of the ferromagnetic powder.

Additives include dispersants, lubricants, abrasives, and the like.

The material for the support is polyethylene terephthalate,
Polyesters such as polyethylene-2,6-naphthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, and cellulose acetate propionate, polyvinyl chloride, polyvinylidene chloride vinyl resins such as
In addition to plastics such as polycarbonate, polyide, and polyamideimide, depending on the application, non-magnetic metals such as aluminum and copper, paper, baryta, or polyethylene, polypropylene, and ethylene-butene copolymers with carbon numbers of 2 or more are used.
Paper such as paper coated or laminated with α-polyolefin No. 10 can also be used.

These supports may be transparent or opaque depending on the intended use of the magnetic recording medium.

Methods for applying the magnetic recording layer onto the support include air doctor coating, blade coating, x7 knife coating, squeeze coating, dip coating, reverse roll coating, transfer roll coating, gravure coating, kiss coating, and cast coating. ,spray·
Various methods such as coating methods can be used, and detailed explanations of these methods can be found in "Coating Engineering" published by Asakura Shoten, pages 253-27.
It is described in detail on page 7 (published on March 20, 1972).

For magnetic sheets, in addition to the required characteristics of binders developed for conventional tapes, we also need to: 1) extend the life of the magnetic sheet when the same track is repeatedly played back;

2) Minimize the variation in track-to-circumference output as much as possible.

3) Increase the reproduction output of the magnetic sheet and increase the recording density.

etc. became extremely important.

For this reason, various countermeasures have been taken in the past, as shown below.

■How to change the magnetic sheet's pace thickness and the magnetic layer's thickness.

2. A method for improving the composition of the magnetic layer of a magnetic sheet.

3. Method of applying lubricant to the surface of the magnetic sheet.

(U.S. Pat. No. 3,719,525, Japanese Patent Application Laid-Open No. 1987-7
No. 4821, No. 48-27705, No. 48-2770
(No. 6) However, the above conventional method had the following drawbacks.

Simply changing the thickness of the base of the magnetic sheet and the magnetic layer tends to cause curling in the sheet, resulting in short sheet life.

It was difficult to create a magnetic layer with excellent sheet suitability by modifying the magnetic layer of a small magnetic sheet.

Among these, sheets capable of high-density recording had a short sheet life.

For this reason, recently, magnetic sheets are capable of high-density recording, but when they have a short lifespan, methods have been adopted in which various types of lubricants are applied to the sheet surface.

Although sheets coated with these lubricants certainly have a longer sheet life, they still have the following drawbacks.

This point will be explained in detail below. When a lubricant is applied to the surface of a magnetic sheet by spraying or using a doctor-proprietary method, the surface of the magnetic sheet is generally coated with an extremely viscous liquid, so the lubricant in the air may
easily adheres, D, 0. was likely to occur.

Because it was difficult to apply the lubricant uniformly, the thickness of the lubricant varied depending on the location, which apparently resulted in a spacing loss between the magnetic head and the magnetic sheet, which tended to increase output fluctuations around the sheet.

When lubricant was applied to the magnetic sheet, the surface of the sheet became sticky, and the sheet stuck to the recorder's back plate, making it difficult to rotate.

As a countermeasure, applying lubricant to a small portion of the seat can prevent the seat and back plate from sticking together, but
Only in that part, the output of the magnetic sheet suddenly decreased due to spacing loss.

In the past, when sticky sheets like octopuses were stored in jackets, they tended to stick to the jacket, and dirt also tended to adhere to them.

Furthermore, in magnetic sheets obtained by this method, lubricant is often applied to the surface of the magnetic layer to a thickness of 1μ or more, so when the sheet is made to have a high density or when a large reproduction output is required, it is difficult to Output was drastically reduced due to bed spacing loss.

This tendency becomes larger as the recording wavelength becomes shorter, and was a fatal drawback when performing high-density recording.

The inventor investigated the cause of this drawback and found that
It has been found that the conventional technology focuses solely on improving the life of the magnetic sheet, and therefore has poor output fluctuations in the magnetic sheet, large amounts of D and O, and poor start characteristics of the recorder.

The inventor has discovered that a magnetic sheet with even better properties can be obtained by heat-treating the sheet after applying the lubricant.

However, when a binder having an incyanate group is used in the magnetic layer, a lubricant other than a lubricant containing active hydrogen capable of reacting with the incyanate group is used.

The present invention will be explained in more detail below.

The magnetic material, binder, and support used in the present invention may be the conventional ones mentioned above.

Any combination of these is effective.1 Generally, high-density recording is possible as a magnetic tape or magnetic sheet, but on the other hand, it is particularly effective when applied in cases where the sheet life is very short.

As a lubricant to be applied to the surface of such a magnetic sheet, hydrocarbon-based (pure hydrocarbon, Uni
oH150, H160, H2SO), liquid paraffin,
Natural baratuin, synthetic paraffin, fatty acid type (stearic acid, oxystearic acid), ester type (lower alcohol ester of fatty acid (butyl stearate, amyl stearate), polyhydric alcohol ester of fatty acid, polyglycol ester of fatty acid, aliphatic alcohol ester), fatty acid ad type [Diamitsu] 2001
Amide API (Torumo Nippon Hydrogen Industry Co., Ltd.), alkylene bis-fatty acid amide], metal soap (sodium oleate), aliphatic alcohol (NAA-46 binazole, NAA-48 binazole from NOF), silicone-based (dimethyl poly siloxane), etc.

Particularly when a binder having an incyanate group is used in the magnetic layer, it is preferable to use a binder based on liquid paraffin, natural paraffin, synthetic paraffin, or silicon.

By combining appropriate amounts of these, methyl ethyl ketone, butyl acetate, tetrachloroethane, isopropyl alcohol,
Apply to the surface of the sheet together with a solvent such as Diflon.

Conventionally, coating methods have been extremely difficult because it has been necessary to coat the magnetic sheet to a sufficiently uniform thickness in order to minimize output fluctuations.

However, in the present invention, the thickness of the coating is not important.

It was sufficient that the lubricant could be applied to the entire surface of the magnetic layer of the magnetic sheet.

The ratio of lubricant to solvent during application is preferably 0.5 to 50 weight da, more preferably 1 to 5 weight da.

These differ depending on the coating method.

Commonly used application methods include spraying, brushing, and doctoring.

The sheet at the time of coating is calendered in advance, and it is generally desirable to use a sheet that can record at a sufficiently high density.

In this way, spray the surface of the sheet to a thickness of about 1 inch.
The various troubles mentioned above occurred on the sheets coated with ~10μ.

The present inventors have discovered that such defects can be improved by further heat-treating the sheet coated with a lubricant.

In other words, simply applying a lubricant to the sheet surface, which has been conventionally done, tends to make the sheet sticky.

In the present invention, by heat treatment, the lubricant penetrates into the inside of the magnetic layer, and a portion of the lubricant adhering to the surface of the sheet dries. There is no lubricant, and the lubricant ends up in the dark spaces inside the magnetic layer of the magnetic sheet.

As a result, the sheet surface was not sticky, and the starting characteristics were good, and the generation of D, O, and the like was reduced.

Furthermore, the amount of lubricant on the surface of the magnetic layer is very small (0,
05μ or less), spacing loss was small, output fluctuations were small, and output drop was also small.

Furthermore, regarding the life of the sheet, there is not a large amount of lubricant attached to the surface as in the past, but on the other hand, there is plenty of lubricant inside the magnetic layer, so if the bed and sheet come into contact, it can ooze out onto the sheet surface. Therefore, the sheet life remained unchanged.

Even better, since a large amount of lubricant is not attached to the sheet surface, the head does not scrape off the lubricant and stain the head.

It is clear that the heat treatment is effective as described above.

The heat treatment temperature is preferably below the glass transition point of the support and binder, and is generally 40°C.
°C to 600C is often used.

Processing time varies depending on the lubricant and solvent used, but 1
This suitable heat treatment time, which is often used from minutes to 15 days, is preferably carried out in a trench where the lubricant adhering to the surface of the sheet is substantially dry.

After such drying, the degree of drying was measured by the following method.

That is, a sheet is set in a sheet recorder, the recording frequency is determined so that the recording wavelength is 2μ, the reproduction output of the sheet is first measured, and then a lubricant is applied to the surface of the same sheet and heat treatment is performed. , re-measure the playback output under the same conditions.

If the difference between these two outputs is large, the drying is not sufficient and the output fluctuations are large, making it unsuitable for high-density recording.

If this output difference is 1 dB or less, higher density is possible, but if it is 0.5 dB or less, it is even better.

In particular, with such heat-treated sheets, sufficient thermal stabilization treatment is performed after the base is made, so the dimensions of the magnetic sheet do not increase as much as before even with large temperature changes, and almost completely Equalized in direction.

As a result, the thermal stability of the sheet is improved, and tracking deviations during high-temperature use are greatly reduced.

In the present invention, the total thickness of the magnetic sheet is from 5 to 500 .mu.m, preferably from 10 to 250 .mu.m, and the flying characteristics deteriorate no matter how thick or thin it is.

The total thickness of the magnetic layer is 0.1 to 50μ, preferably 1 to 50μ.
With a thickness of 15μ, it is difficult to make whether thick or thin; if it is too thick, it is difficult to perform high-density recording, and if it is too thin, its life tends to be shortened.

The coating thickness of the lubricant is 0.1 to 10□, preferably 0.1
The thickness is ~3μ, and if it is thin, it will be difficult to apply, and if it is thick, it will take a long time to heat treat.

The heat treatment temperature is below the glass transition point of the base binder, preferably 40 to 60°C, and the heat treatment time is 15 days or less, although it varies depending on the heat treatment temperature.

And the output difference between the sheets is 1 dB or less, preferably 0.5
dB or less.

The following effects were achieved by the present invention.

1, D, 0. A magnetic sheet with less was created.

2. - We were able to create a seat with little output fluctuation between laps.

3. I was able to create a seat that was easy to start and stop.

4. We were able to create a sheet that is capable of high-density recording and has little output loss.

5. We were able to create a sheet with a long life.

6. Tracking and misalignment during high-temperature playback have become smaller.

7. I was able to make a sheet that can be stored in a jacket.

Example 1 A coating solution having the following composition was coated to a thickness of 7 μm on a polyethylene terephthalate support having a thickness of 22 μm without magnetic field orientation treatment.

After drying, the coated surface was polished using a calendar roll.

Thereafter, it was cut into a magnetic sheet with an outer diameter of 200mm and an inner diameter of 25mm, and tested on the items shown in Table 1.

As a lubricant, dimethylpolysiloxane was used in a Diflon solvent in an amount of 3 parts by weight.

The coating method was ``brush coating'' and the lubricant was applied to the entire surface of the sheet.

Thereafter, heat treatment was performed in air under the conditions shown in the table.

A sheet recorder having the shape shown in FIG. 1 was used.

The rotational speed of the recorder was 1800 rpm, and the head was ferrite.

The results are shown in Table-1. Coating composition/magnetic material (r-Fe203 particle size 0.05μφx0
．． 4μ) 301 ・Vinyl chloride-vinyl acetate copolymer (copolymerization ratio 87:13 degree of polymerization 350) 309 ・Polyester・Polyol (hydroxyl value 180) ・・・・・・・・・・・・
12g soybean lecithin...
...... 3g polyisocyanate (75 weight polyethyl acetate solution of the reaction product of 3 moles of 2,4-tolylene diisocyanate compound and 1 mole of trimethylolpropane) 3g - Methyl ethyl ketone ...・・・・・・
・600g・Toluene ・・・・・・
...300g Example 2 A coating solution having the following composition was coated on a polyethylene terephthalate support having a thickness of 36μ to a thickness of 4.5μ without magnetic field orientation treatment.

After drying, the coated surface was polished using a calendar roll.

Thereafter, the same tests as in Example 1 were conducted.

Arustearate was used as a lubricant.

The coating method was a spray method, and the coating was applied to the surface of the sheet at a concentration of over 5% by weight in Freon gas.

Thereafter, heat treatment was performed in air under the conditions shown in the table.

The recorder and sheet dimensions used were the same as in Example 1.

The results are shown in Table 2. Coating composition: Magnetic material (Co1.8-rich γ-Fe203 particle size 0
．． 05μφ×0.3μ) ・・・・・・・・・・・・3
0 (Bi7・Nitrocellulose (nitrogen content 11.2-12.3 degree of polymerization 550) 5 g ・Vinyl chloride-vinylidene chloride copolymer (copolymerization ratio = 7 = 3 degree of polymerization - 400) 14.2.!i / Epoxy resin (reaction product of bisphenol A and epichlorohydrin, molecular weight = 900, epoxy equivalent -460 to 5201, hydroxyl group content = 0.29, -
I-Picot 10d)・・・・・・・・・・・・ 12
g ・Soybean lecithin・・・・・・・・・・・・
・・Aluminum oxide (average particle size 4μ) 2g 2g ・Carbon black (average particle size 2μ)・・・・
・・・・・・・・・ li・Incyanate compound (3 moles of 2.4-) A 75 gravimetric ethyl acid solution of the reaction product of a lylene diisocyanate compound and 1 mole of trimethylolpropane Bayer's Desmodur L- 75) 1.2g - Butyl acetate 80g The following can be said from the above examples.

1. Seats coated with lubricant have a long service life.

2. It is difficult to start and stop the lubricant-applied sheet, and after 50 hours, the lubricant and 0 increase, and furthermore, the output fluctuation becomes large and the output decreases.

3. Sheets that are not heat treated have large track deviations.

On the other hand, for sheets that have dried after applying lubricant, 4. Long seat life.

5. The sheet output fluctuation is small and the output is large.

6. Track deviation is small.

In particular, the start and stop characteristics will be greatly improved for sheets that have been heat-treated, where the output difference will be less than 1.0 dB.

7. These features are effective even if the magnetic material and binder of the magnetic sheet, the thickness of the support, the total thickness, etc. are known.

From the above, it was found that the present invention is effective.

Next, preferred embodiments of the present invention will be listed.

(2) After sheet coating and surface polishing, a lubricant is applied to the sheet as small pieces or donuts, and then heat treatment is performed.

2. After sheet coating and surface polishing, 11 lubricant is applied to the roll, and then heat treatment is performed to obtain the sheet size.

3. A method of applying lubricant during sheet coating and surface polishing, and then heat treatment.

4. A method of applying a sheet, then applying a lubricant, performing heat treatment, and then polishing the surface.

[Brief explanation of drawings]

Figure 1 shows the state of recording on a magnetic sheet.

Claims (1)

[Claims] 1 In a magnetic sheet with a magnetic layer provided on a supporting base,
After providing a lubricating layer on the surface of the magnetic layer (when using a binder having an incyanate group in the magnetic layer, excluding one made of a lubricating substance having an active hydrogen group that can react with the incyanate group), heat treatment is performed. and this heat treatment,
Reproduction output of the sheet when the magnetic layer is provided on the supporting substrate (
4) and a magnetic sheet obtained by performing the above heat treatment at a temperature where the difference in reproduction output (B) is 1 dB or less.