JPH04357099A - Magnetic card having polishing properties - Google Patents

Abstract

PURPOSE:To ensure that the magnetic head of a terminal device is not damaged and a contaminant is removed to prevent a write and read error occurrence by providing a polishing layer containing a metal oxide such as silica or alumina on a magnetic layer. CONSTITUTION:The subject magnetic card consists of a sheet-like or a plate-like base, a magnetic layer formed on the base and a polishing layer formed on the magnetic layer. Especially the polishing layer containing silica and a metal oxide selected from among alumina, titanium oxide, chromium oxide and ferric oxide is provided on the magnetic layer. The polishing layer has a film whose thickness ranges from 1 to 9mum. In addition, the blend ratio of silican and the metal oxide in the polishing layer ranges from 3 to 50wt.%. Subsequently, a contaminant sticking to a magnetic head can be removed without damaging the magnetic head. Further, the contaminant does not cause a space loss with the magnetic head and therefore, the output variation rate of the magnetic card does not deteriorate.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abrasive magnetic card.

0002

2. Description of the Related Art Depending on the environment in which prepaid cards are used, their surfaces become contaminated with dirt and grime. When such a card is used in a terminal device, the dirt adheres to the magnetic head of the terminal device, causing reading errors and the like. In order to prevent this, it is necessary to perform maintenance on the terminal magnetic head at regular intervals to remove dirt. However, it is impossible to perform maintenance on all of these terminals installed over a wide area, and it is necessary to make the terminal magnetic heads maintenance-free by some method. Conventionally, a known method for removing dirt from the magnetic head of a terminal device is to provide an abrasive layer on the surface of a magnetic card and use the abrasive effect of the abrasive layer to remove the dirt.

0003

[Problems to be Solved by the Invention] However, the above-mentioned conventional cards have a layer containing an extremely hard abrasive pigment on the surface of the card, so they have a high abrasive power and have a great effect on removing dirt, but they do not work well with terminals. This also polishes the machine magnetic head, shortening its lifespan. Furthermore, the abrasive pigment is generally in the form of fine particles, resulting in a smooth abrasive surface. For this reason, once the dirt has been removed, it remains on the card surface, and when the card is used again, this dirt acts as a space loss between the card and the magnetic head of the terminal, increasing the card's output fluctuation rate. However, there is a problem that writing or reading errors may occur.

The problem to be solved by the present invention is to solve the above-mentioned drawbacks of conventional cards, remove contaminants without damaging the magnetic head of the terminal, and remove the contaminants once removed from the rough surface. The purpose of the present invention is to provide a magnetic card that has a polishing layer that retains the magnetic head and prevents writing and reading errors, and enables maintenance-free maintenance of the magnetic head of a terminal device.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a magnetic recording layer containing a material selected from the group consisting of (1) silica and (2) alumina, titanium oxide, chromium oxide, and ferric oxide. Provided is a magnetic card characterized by having a polishing layer containing a metal oxide.

[0006] The present invention will be explained below with reference to preferred embodiments shown in the drawings. A magnetic card A according to the present invention includes, for example, (a) a sheet-like or plate-like base 1, a magnetic layer 2 provided thereon, and a magnetic layer 2 provided on the magnetic layer 2, as shown in FIG. A magnetic card comprising a polished layer 3.

(b) As shown in FIG. 2, a sheet-like or plate-like base 1, a magnetic layer 2 provided thereon, and a polishing layer 3 provided on a part of the magnetic layer 2. For example, a magnetic card consisting of:

The substrate 1 is in the form of a sheet or a plate, and examples of the material for the substrate 1 include nylon, cellulose diacetate, cellulose triacetate, polystyrene, polyethylene, polypropylene, polyester, polyethylene terephthalate, and polyimide. Examples include plastics; metals such as copper and aluminum; paper and impregnated paper; these materials can be used alone or in combination to form a composite. A preferable material may be selected as appropriate from among the above-mentioned materials, taking into consideration the physical properties required of the substrate, such as strength, rigidity, hiding power, and optical opacity. Note that the thickness of the base 1 is 0.005 to 5 mm.
A range of is preferred.

The magnetic layer 2 is made of, for example, γ-Fe2O3, C
o Adhesion γ- Fe2O3, Fe3O4, CrO2, F
e, Fe-Cr, Fe-Co, Co-Cr, Co-Ni
, MnAl, Ba ferrite, Sr ferrite, and other known magnetic particles are dispersed in a suitable resin or ink vehicle using a gravure method, a reverse method,
It can be formed on the substrate 1 by a known coating method such as a knife edge method.

[0010] Furthermore, the magnetic layer 2 is made of Fe, Fe-Cr, F
It can also be formed on the base 1 by vacuum evaporation, sputtering, plating, etc. using metals or alloys such as e-Co and Co-Cr.

When the magnetic layer 2 is formed by a coating method, the film thickness is preferably in the range of 1 to 100 μm;
A range of ˜20 μm is most preferred.

[0012] When the magnetic layer 2 is formed by a vacuum evaporation method, a sputtering method, a plating method, etc., the film thickness is preferably in the range of 100A to 1μm, and preferably in the range of 500 to 2000μm.
The range A is particularly preferred.

Examples of the binder resin or ink vehicle in which magnetic fine particles such as γ-Fe2O3 are dispersed include butyral resin, vinyl chloride-vinyl acetate copolymer resin, urethane resin, polyester resin, cellulose resin, acrylic resin, and styrene-malein. Examples include acid copolymer resins. Further, rubber resins such as nitrile rubber, urethane elastomers, etc. can be added to these resins as necessary. Furthermore, surfactants, silane coupling agents, plasticizers, waxes, silicone oils, carbon, and other pigments may be added to the dispersion in which magnetic fine particles are dispersed in the resin, as required.

The proportion of magnetic fine particles in the dispersion containing magnetic fine particles is preferably in the range of 65 to 90% by weight.

The polishing layer 3 is made by dispersing (1) silica and (2) a metal oxide selected from the group consisting of alumina, titanium oxide, chromium oxide, and ferric oxide in a suitable binder or ink vehicle. The dispersion can be provided on the magnetic layer 2 by a conventionally known coating method such as a gravure method, a reverse method, a knife edge method, or a silk screen method.

Examples of the silica used in the present invention include "Syroid 63" and "Syroid 63" manufactured by Fuji Davison Chemical Co., Ltd.
Thyroid 65”, “Thyroid 72”, “Thyroid 74”, “Thyroid 105”, “Thyroid 244”
, "Thyroid 308", "Thyrophobic 100"
, "Aerosil OX-50" manufactured by Nippon Aerosil Co., Ltd.
, "Aerosil 1130", "Aerosil 200", "
Examples include "Aerosil 300" and "Aerosil 380."

Examples of the alumina used in the present invention include "UA-5025" and "UA
-5055'', ``UA-5205'', ``Mechanox UB-10'' manufactured by Murakami Industries, Ltd., ``High Purity Alumina AKP-18'' and ``High Purity Alumina AKP-20'' manufactured by Sumitomo Chemical Industries, Ltd. etc.

[0018] Examples of the titanium oxide used in the present invention include "Tiepeke R-820" manufactured by Ishihara Sangyo Co., Ltd.
"Tiepeke R-830", "Tiepeke CR-50"
, "Tiepeke CR-80", "Tiepeke CR-85"
], "Typeke Yellow TY-50", "Typeke Yellow TY-70", "Typeke JR" manufactured by Teyka Co., Ltd.
-603", "Teika JR-602", "Teika JR-
701'' and ``Tayka JR-801''.

Examples of the chromium oxide used in the present invention include "chromium oxide ND-801" manufactured by Nippon Denko Co., Ltd.
"Chromium oxide ND-802", "Chromium oxide ND-80"
3", "Chromium oxide for polishing" manufactured by Nihon Kagaku Kogyo Co., Ltd., and the like.

[0020] Examples of the ferric oxide used in the present invention include "Toda Color 100ED" manufactured by Toda Kogyo Co., Ltd.;
"Todacolor 130ED", "Todacolor 160ED"
etc.

Examples of the resin or ink vehicle in which (1) silica and (2) a metal oxide selected from the group consisting of alumina, ferrous oxide, chromium oxide, and titanium oxide are dispersed include butyral resin and vinyl chloride. -Vinyl acetate copolymers, urethane resins, polyester resins, acrylic resins, epoxy resins and the like. Moreover, urethane elastomer or the like can be added to these resins, if necessary. Also, in this dispersion, (1)
Silica and (2) alumina, titanium oxide, chromium oxide,
In addition to the metal oxide selected from the group consisting of ferric oxide, aluminum pigments, mica pigments, organic pigments for coloring, etc. can also be added as necessary. Furthermore, surfactants, silane coupling agents, wax, etc. can also be added as necessary.

When the polishing layer 3 is formed on the magnetic layer 2 by a coating method, its thickness is preferably in the range of 1 to 9 μm, particularly preferably in the range of 2 to 7 μm. If the film thickness is less than 1 μm, it tends to be unable to retain the dirt removed from the terminal magnetic head, and if the film thickness is more than 9 μm, the magnetic dynamic characteristics, especially the frequency characteristics, of the magnetic card will deteriorate. This is undesirable because it tends to cause problems with magnetic properties, such as poor reading.

The surface roughness (Ra) of the polishing layer 3 formed on the magnetic layer 2 by the coating method is preferably in the range of 0.2 to 1.6 μm, most preferably in the range of 0.4 to 1.3 μm. If the surface roughness is less than 0.2 μm, it tends to be unable to retain the dirt removed from the terminal magnetic head, and if the surface roughness is more than 1.6 μm, the magnetic dynamic characteristics of the magnetic card will deteriorate. In particular, the frequency characteristics deteriorate,
This is undesirable because it tends to cause problems with magnetic properties such as poor reading.

The blending ratio of silica and titanium oxide in the polishing layer 3 is preferably in the range of 3 to 50% by weight, particularly preferably in the range of 5 to 30% by weight. If the blending ratio is less than 3% by weight, the effect of polishing dirt adhering to the terminal magnetic head tends to disappear, and if the blending ratio is more than 50% by weight, the durability of the polishing layer decreases and the running This is undesirable because the polishing layer tends to be scraped away by the terminal magnetic head and contaminate the magnetic head.

The ratio of silica and titanium oxide used in the polishing layer 3 is preferably in the range of 5:1 to 1:5 by weight;
:1 to 1:4 is particularly preferred. If the ratio of titanium oxide used is more than 1:5, the abrasiveness is too high, which tends to shorten the life of the magnetic head of the terminal, and furthermore, it tends to be unable to retain the dirt removed from the magnetic head of the terminal. It is not desirable because it is in Further, if the ratio of silica used is more than 5:1, the effect of polishing dirt attached to the magnetic head of the terminal device tends to be reduced, which is not preferable.

[0026]

[Examples] The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. Note that "%" and "parts" in the examples represent "% by weight" and "parts by weight", respectively.

(Preparation of magnetic paint) "BOP-90" (barium ferrite magnetic powder manufactured by Nippon Bengara Kogyo Co., Ltd.) 100 parts "VAG
H” (vinyl chloride-vinyl acetate copolymer manufactured by UCC, USA) 20 parts “Crisbon 7209” (
Polyurethane resin (manufactured by Dainippon Ink and Chemicals Co., Ltd.) 45
part oleic acid

Part 3 Methyl ethyl ketone
97 copies
toluene

Part 97 Cyclohexanone

49 parts of each of the above compositions were kneaded for 20 hours using a ball mill to prepare a magnetic paint.

(Preparation of alumina paint) "Mechanoc UB-10" (alumina manufactured by Murakami Industries Co., Ltd.) 100
Department “VAGH”

100 parts lecithin


1.5 parts methyl ethyl ketone

187 parts toluene


187 parts Each of the above compositions was mixed with 23 parts using a ball mill.
An alumina paint was prepared by kneading for hours.

(Composition of polishing paint A) "Syroid 74" (silica manufactured by Fuji Davison Chemical Co., Ltd.) 1.6 parts
"CR808CM" (Asahi Kasei Metals Co., Ltd. aluminum paste, active ingredient 49% or more)


3.3 parts Above alumina paint

Part 3.1 “V
AGH”

Part 5.6 “Pandex T-5260
-35MT” (polyurethane resin manufactured by Dainippon Ink and Chemicals Co., Ltd.)

16.2 parts dibutyltin dilaurate
0
．． Part 01 Methyl ethyl ketone

35.1 parts toluene


35.1 parts Each of the above compositions was stirred for 1 hour using a dispersion stirrer to prepare polishing paint A.

(Preparation of Bengara paint) “Todacolor 160ED” (oxidation No. 2 manufactured by Toda Kogyo Co., Ltd.)
iron pigment) 100 parts
"VAGH"

100 parts lecithin

1
．． 5 parts Methyl ethyl ketone

187 parts toluene


187 parts of each of the above compositions were kneaded for 23 hours using a ball mill to prepare a Bengara paint.

(Composition of polishing paint B) "Syroid 74"

Part 1.6 “CR808CM”


3. Part 3 Bengara paint above

Part 3.1 “VA
GH”

Part 5.6 “Pandex T-5260-
35MT”
16.2 parts dibutyltin dilaurate
0
．． Part 01 Methyl ethyl ketone

35.1 parts toluene


35.1 parts Each of the above compositions was stirred for 1 hour using a dispersion stirrer to prepare polishing paint B.

(Composition of chromium oxide paint) "Chromium oxide ND-801" (chromium oxide pigment manufactured by Nippon Denko Co., Ltd.) 100 parts
"VAGH"

100 parts lecithin

1
．． 5 parts Methyl ethyl ketone

187 parts toluene


187 parts Each of the above compositions was kneaded for 30 hours using a ball mill to prepare a chromium oxide paint.

(Composition of polishing paint C) "Syroid 74"

Part 1.6 “CR808CM”


3.3 parts of the above chromium oxide paint

Part 3.1 “VAGH”


Part 5.6 “Pandex T-5260-35M
T”
16.2 parts dibutyltin dilaurate
0.01
Part Methyl ethyl ketone

35.1 parts toluene

35
．． One part of each of the above compositions was stirred for 1 hour using a dispersion stirrer to prepare an abrasive paint.

(Preparation of titanium oxide paint) "Tiepeke R-830" (titanium oxide pigment manufactured by Ishihara Sangyo Co., Ltd.) 100 parts
"VAGH"

100 parts lecithin

1
．． 5 parts Methyl ethyl ketone

187 parts toluene


187 parts Each of the above compositions was kneaded for 30 hours using a ball mill to prepare a titanium oxide paint.

(Preparation of polishing paint D) “Syroid 74”

Part 1.6 “CR808CM”


3.3 parts titanium oxide paint

Part 3.1 “VAG
H”

Part 5.6 “Pandex T-5260-3
5MT”
16.2 parts dibutyltin dilaurate
0.
Part 01 Methyl ethyl ketone

35.1 parts toluene


35.1 parts Each of the above compositions was stirred for 1 hour using a dispersion stirrer to prepare an abrasive paint.

(Preparation of polishing paint E) “Syroid 74”

0.53 part “CR808CM”


5.50 parts titanium oxide paint

Part 3.10 “VAG
H”

5.43 part “Pandex T-5260-3
5MT”
16.20 parts dibutyltin dilaurate
0.
Part 01 “Sasol Wax SPN-3” (wax manufactured by Sasol Corporation, South Africa)


0.40 parts methyl ethyl ketone
34.60 parts toluene

34.60 parts Each of the above compositions was stirred for 1 hour using a dispersion stirrer to prepare polishing paint E.

(Preparation of polishing paint F) “Syroid 74”

0.19 part “CR808CM”


1.94 parts titanium oxide paint

Part 1.08 “VAG
H”

Part 6.64 “Pandex T-5260-3
5MT”
19.51 parts dibutyltin dilaurate
0.
Part 01 Methyl ethyl ketone

35.30 parts toluene

3
Polishing paint F was prepared by stirring 5.30 parts of each of the above compositions for 1 hour using a dispersion stirrer.

(Preparation of polishing paint G) “Syroid 74”

4.10 parts titanium oxide paint

23.60
Section “Pandex T-5260-35MT”

7.50 parts dibutyltin dilaurate
0.01 part methyl ethyl ketone

32.40 parts toluene

32.40 parts Each of the above compositions was stirred for 1 hour using a dispersion stirrer to obtain polishing paint G.
was prepared.

(Preparation of polishing paint H) “Syroid 74”

1.86 copies “CR808CM”


3.3 parts titanium oxide paint

1.78 parts “VAG
H”

5.83 parts “Pandex T-5260-3
5MT”
16.2 parts dibutyltin dilaurate
0.
Part 01 Methyl ethyl ketone

35.51 parts toluene

3
5.51 parts Each of the above compositions was stirred for 1 hour using a dispersion stirrer to prepare polishing paint H.

(Preparation of polishing paint J) “Syroid 74”

0.31 part “CR808CM”


3.30 parts titanium oxide paint

10.70 part “VAG
H”

Part 4.28 “Pandex T-5260-3
5MT”
16.20 parts dibutyltin dilaurate
0.
Part 01 Methyl ethyl ketone

32.60 parts toluene

3
2.60 parts of each of the above compositions were stirred for 1 hour using a dispersion stirrer to prepare polishing paint J.

(Example 1) On a polyethylene terephthalate sheet with a thickness of 188 μm, 100 parts of the above magnetic paint and “Burnock D-750” (Dainippon Ink & Chemicals Co., Ltd.)
A paint consisting of 3 parts of Polyisocyanate (manufactured by Co., Ltd.) was applied in a reverse manner so that the dry film was 12 μm, and then 100 parts of the above "abrasive paint A" and 5 parts of "Burnock D-750" were applied in the same manner. The dry film thickness of the paint consisting of is 6
A magnetic card was produced by applying the solution to a thickness of μm. Note that the dry film thickness of the magnetic paint and the dry film thickness of the abrasive paint were measured using a stylus type film thickness meter.

[0042] Furthermore, the surface roughness of the dry coating film of the abrasive paint is
Tokyo Seimitsu Co., Ltd. “Surfcom, Model E-RC-S01
When measured using "A", Ra was 0.98 μm.

(Example 2) In Example 1, 100 parts of the above-mentioned "abrasive paint B" and "Burnock D-750" were used instead of the paint consisting of 100 parts of "abrasive paint A" and 5 parts of "Burnock D-750". A magnetic card was prepared in the same manner as in Example 1, except that a 5-part paint was used.

Furthermore, when the surface roughness of the dry coating film of the abrasive paint was measured in the same manner as in Example 1, the Ra was 0.94μ.
It was m.

(Example 3) In Example 1, 100 parts of the above-mentioned "abrasive paint C" and "Burnock D-750" were used instead of the paint consisting of 100 parts of "abrasive paint A" and 5 parts of "Burnock D-750". A magnetic card was prepared in the same manner as in Example 1, except that a 5-part paint was used.

Furthermore, when the surface roughness of the dry coating film of the abrasive paint was measured in the same manner as in Example 1, the Ra was 1.03μ.
It was m.

(Example 4) In Example 1, 100 parts of the above-mentioned "abrasive paint D" and "Burnock D-750" were used instead of the paint consisting of 100 parts of "abrasive paint A" and 5 parts of "Burnock D-750". A magnetic card was prepared in the same manner as in Example 1, except that a 5-part paint was used.

[0048] Furthermore, when the surface roughness of the dry coating film of the abrasive paint was measured in the same manner as in Example 1, the Ra was 0.89μ.
It was m.

(Example 5) In Example 1, 100 parts of the above-mentioned "abrasive paint E" and "Burnock D-750" were used instead of the paint consisting of 100 parts of "abrasive paint A" and 5 parts of "Burnock D-750". A magnetic card was prepared in the same manner as in Example 1, except that a 5-part paint was used.

[0050] Furthermore, when the surface roughness of the dry coating film of the abrasive paint was measured in the same manner as in Example 1, the Ra was 0.66 μm.
It was m.

(Example 6) In Example 1, 100 parts of the above-mentioned "abrasive paint D" and "Burnock D-750" were used instead of the paint consisting of 100 parts of "abrasive paint A" and 5 parts of "Burnock D-750". A paint consisting of 5 parts has a dry film thickness of 0.
．． A magnetic card was produced in the same manner as in Example 1, except that the coating was applied to a thickness of 74 μm.

[0052] Furthermore, when the surface roughness of the dry coating film of the abrasive paint was measured in the same manner as in Example 1, the Ra was 0.14μ.
It was m.

(Example 7) In Example 1, 100 parts of the above-mentioned "abrasive paint D" and "Burnock D-750" were used instead of the paint consisting of 100 parts of "abrasive paint A" and 5 parts of "Burnock D-750". A paint consisting of 5 parts has a dry film thickness of 1
A magnetic card was produced in the same manner as in Example 1, except that the coating was applied to a thickness of 1 μm.

[0054] Furthermore, when the surface roughness of the dry coating film of the abrasive paint was measured in the same manner as in Example 1, the Ra was 1.93μ.
It was m.

(Example 8) In Example 1, 100 parts of the above-mentioned "abrasive paint F" and "Burnock D-750" were used instead of the paint consisting of 100 parts of "abrasive paint A" and 5 parts of "Burnock D-750". A magnetic card was prepared in the same manner as in Example 1, except that a 5-part paint was used.

[0056] Furthermore, when the surface roughness of the dry coating film of the abrasive paint was measured in the same manner as in Example 1, the Ra was 0.12μ.
It was m.

(Example 9) In Example 1, 100 parts of the above-mentioned "abrasive paint H" and "Burnock D-750" were used instead of the paint consisting of 100 parts of "abrasive paint A" and 5 parts of "Burnock D-750". A magnetic card was prepared in the same manner as in Example 1, except that a 5-part paint was used.

Furthermore, when the surface roughness of the dry coating film of the abrasive paint was measured in the same manner as in Example 1, the Ra was 1.12 μm.
It was m.

(Example 10) In Example 1, 100 parts of the above-mentioned "abrasive paint J" and "
A magnetic card was produced in the same manner as in Example 1, except that a paint consisting of 5 parts of "Burnock D-750" was used.

[0060] Furthermore, when the surface roughness of the dry coating film of the abrasive paint was measured in the same manner as in Example 1, the Ra was 0.21μ.
It was m.

(Evaluation of magnetic cards) The magnetic cards obtained in each example were evaluated for head removal properties, contaminant retention properties, head polishing properties, and frequency characteristics, and the results are listed in Table 1. . In addition, the removability of head deposits, re-adhesion prevention properties,
The evaluation criteria for head polishability and frequency characteristics are as follows.

(Removal of deposits on the head) The surface of the magnetic head was immersed in a cola solution for 1 minute, taken out, and dried at room temperature to form a deposit film. Using this head,
The magnetic cards obtained in each example were run 10 times at a head pressing force of 350 g and a running speed of 190 mm/sec, and the state of deposits on the magnetic head was observed.

○: Adhesive matter on the magnetic head has been completely removed. Δ: Most of the deposits on the magnetic head have been removed, but some deposits can be seen within a range that does not have an adverse effect.

x: The deposits on the magnetic head were not removed at all.

(Contaminant Retention Ability) Cola liquid was applied to the surface of the magnetic head using a cotton swab and dried at room temperature. After running the magnetic cards obtained in each example 100 times at a head pressing force of 300 g and a running speed of 190 mm/sec, the output fluctuation rate was calculated according to the formula below, and the amount of contamination was determined based on the magnitude of the output fluctuation rate. Indicates the quality of object retention.

[0066]

[Math 1]

(Head polishability) The magnetic cards obtained in each example were subjected to a head pressing force of 350 g and a running speed of 190 mm/
The polishing state of the magnetic head was observed by running it 1000 times in seconds.

○: The magnetic head is not polished. Δ: The magnetic head is slightly polished to the extent that no adverse effects are caused. ×: The magnetic head is considerably polished.

(Frequency characteristics) The magnetic cards obtained in each example were tested using a magnetic card output inspection machine manufactured by Apollo Mec at a head pressing force of 300 g, a running speed of 190 mm/sec, a recording density of 200 FCI and 500 FCI, and a recording current value of 600 m.
500FCI and 200FCI when recorded and played back with A
The output ratio was calculated based on the following formula.

[0070]

[Math 2]

[0071]

[Table 1]

From the results listed in Table 1, it can be seen that the magnetic cards obtained in each example were able to remove contaminants attached to the magnetic head, which was the original purpose, and did not damage the magnetic head.
In addition, the removed contaminants are retained within the surface roughness of the polishing layer,
It does not degrade the output fluctuation rate of the magnetic card and has frequency characteristics that pose no problem in practical use of the magnetic card.

However, compared to the magnetic cards of Examples 1 to 5, the magnetic card of Example 6 has a thinner polishing layer, so the retention of contaminants is slightly lower and the rate of output fluctuation is slightly lower. The magnetic card of Example 7 has a thick polishing layer, so the frequency characteristics are slightly low.The magnetic card of Example 8 has a low blending ratio of silica and titanium oxide in the polishing layer, so it is free from contaminants. The magnetic card of Example 9, which has a slightly lower removability, has a higher proportion of silica and titanium oxide in the polishing layer, so the magnetic card of Example 9 has a slightly lower contaminant removability.
0 magnetic cards use a large proportion of titanium oxide in the polishing layer, so the polishing force tends to be a little too strong, causing some damage to the magnetic head.

[0074]

[Effects of the Invention] The magnetic card according to the present invention can remove contaminants attached to the magnetic head without damaging the magnetic head, and retain the removed contaminants within the roughness of the surface of the polishing layer. Therefore, contaminants do not cause space loss with the magnetic head and do not reduce the output fluctuation rate of the magnetic card. Furthermore, since the magnetic card does not contaminate the magnetic head of the terminal, maintenance of the terminal becomes unnecessary.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a magnetic card according to the present invention.

FIG. 2 is a sectional view of a magnetic card according to the present invention.

[Explanation of symbols]

1 Base 2 Magnetic layer 3 Polishing layer

Claims (5)

[Claims] Claim 1: On a magnetic recording layer, (1) silica and (2)
) A magnetic card comprising a polishing layer containing a metal oxide selected from the group consisting of alumina, titanium oxide, chromium oxide and ferric oxide. 2. The magnetic card according to claim 1, wherein the polishing layer has a thickness in the range of 1 to 9 μm. [Claim 3] The surface roughness (Ra) of the polishing layer is from 0.2 to
The magnetic card according to claim 1 or 2, wherein the magnetic card has a thickness in the range of 1.6 μm. 4. Claim 1, 2 or 3, wherein the blending ratio of silica and metal oxide in the polishing layer is in the range of 3 to 50% by weight.
Magnetic card as described. 5. Claim 4, wherein the ratio of silica and metal oxide used in the polishing layer is in the range of 5:1 to 1:5 by weight.
Magnetic card as described.