JPS6233326A - Heat sensitive magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the reading of a prescribed signal and to prevent forgery by incorporating zinc oxide and/or UV absorbent into one layer among the respective laminated layer among the respective laminated layers for heat sensitive recording constituted by successively providing a leuco dye heat sensitive color forming layer, barrier layer and protective layer on the other surface of a base. CONSTITUTION:Normal data is recorded to the high coercive force layer of a magnetic recording medium constituted by successively laminating the high coercive force magnetic layer 12,high magnetic permeability layer 13 and low coercive force magnetic layer 14 on one surface of the base 11 consisting of a nonmagnetic sheet such as polyester film and a dummy signal is recorded to the low coercive force layer. The lueco dye heat sensitive color forming layer 16, barrier layer 17 and protective layer 16 are successively provided on another surface of the base. The zinc oxide and/or UV absorbent is incorporated into at lest one of these three layers. The high magnetic permeability layer 13 is magnetically saturated when a card for reproduction is brought into tight contact with the magnetic surface and a magnetic field for transfer is applied thereto. The magnetic permeability is then decreased and the magnetic shielding effect is lost. The normal data recorded to the high coercive force layer 12 and the dummy signal recorded to the low coercive force layer 14 are thereby mixedly reproduced on the card for reproduction. The forgery is thus prevented.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a heat-sensitive magnetic recording medium used for ticket purchases, public phone tickets, etc., bus coupons, commuter passes, etc. This invention relates to a heat-sensitive magnetic recording medium that is highly resistant to counterfeiting and in which a predetermined recorded signal cannot be read unless a predetermined operation is performed on and ().

<Prior Art> In recent years, magnetic cards have become rapidly popular in the form of cash coupons, magnetic coupon tickets, road passes, commuter passes, and the like. In this case, it is necessary to record visible information on the other side of the support with a magnetic recording layer, such as a balance display that changes each time a customer uses the card, or the card's validity period, date of issue, etc. . As a means for performing such recording, thermal recording, which can obtain clear images simply by heating, is attracting much attention as a recording layer constituting the back side of a magnetic card.

With the expansion of the use of thermosensitive magnetic recording media, it has become possible to easily read and rewrite signals recorded on magnetic media using commercially available playback devices, making it possible for conventional magnetic recording media to It is not possible to effectively prevent counterfeiting.

-As is clear from its use, the heat-sensitive recording layer applied to force-sensitive thermomagnetic recording media is required to have extremely harsh practical characteristics in terms of ease of handling and frequency of use for customers' cards, compared to those for ordinary facsimile machines. There is. Therefore, if the leuco dye-based heat-sensitive material in the prior art is applied as it is to the recording layer of a magnetic recording medium that is exposed to harsh usage conditions as in the present invention, there will be serious problems in practical properties, especially light resistance. It was a big problem.

<Problems to be Solved by the Invention> The present invention has been made in view of the above circumstances, and provides a heat-sensitive magnetic material that is effective in preventing forgery of magnetic signals and that improves the severe light resistance required for heat-sensitive recording layers. It provides a recording medium.

<Means for Solving the Problems> The present invention provides a high coercive force magnetic layer, a high permeability magnetic layer, and a low coercive force magnetic layer on one side of a support made of a nonmagnetic sheet such as a polyester film. The purpose of preventing counterfeiting is achieved by recording regular data on the high coercive force layer and recording dummy signals on the low coercive force layer of the magnetic recording medium, which are sequentially laminated as shown in FIG. In this case, the high coercive force magnetic layer is made of barium ferrite or strontium ferrite with a coercive force of 1500 to 5000 oersted, and the high permeability magnetic layer is made of materials such as sendust or permalloy, and the resistive magnetic layer is made of materials such as sendust or permalloy. is like iron oxide magnetic powder 200~10
00 millstones are preferably used in the present invention, and these are coated on a support together with a binder such as polyester resin or vinyl chloride resin, and dried to form three magnetic layers.

Further, a white protective layer may be formed on the three-layer magnetic layer, if necessary.

Next, the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a cross-sectional view in the width direction showing an embodiment of a thermosensitive magnetic recording medium. A support 11, a high coercive force layer 12, a high permeability layer 13, a low coercive force layer 14, a protective printing layer 15, and a protective layer 18 is formed on a leuco dye-based thermosensitive coloring layer 16 via a barrier layer 17. It is provided.

Regular data is recorded on the high coercive force layer 12 of this thermosensitive recording medium by a magnetic head, and then a dummy signal is recorded on the resistive magnetic layer 14. At this time, if an appropriate recording current is applied to the magnetic head, the normal data on the high coercive force layer 12 will not be affected. When the thus recorded information on the magnetic card is reproduced, the normal data in the high coercive force layer 12 is magnetically shielded by the high magnetic permeability layer 13, and is hardly detected as an output. What is sensed is only the dummy signal of the resistive magnetic layer, which is observed as if it were regular data.

It is assumed that an attempt is made to copy this magnetic card using the contact transfer method. When a replication card is brought into close contact with a magnetic surface and a transfer magnetic field is applied, the high magnetic permeability layer 13 is magnetically saturated due to the transfer magnetic field and its magnetic permeability decreases, resulting in no magnetic shielding effect. The normal data recorded on the high coercive force layer 12 and the dummy signal recorded on the resistive magnetic layer 14 are mixed and duplicated.

Actually, there are 4 reading methods when using this magnetic card.
This is done using a reading device with a magnetic head. As shown in FIG. 2, the first magnetic head 21 reads the dummy signal recorded on the low coercive force layer 14, confirms that the card is a legitimate card, and then sends this signal to the second magnetic head 22. Demagnetize with.

Next, the third magnetic head 23 reads the regular data, and the fourth magnetic head 23 reads the regular data.
The magnetic head 24 records new data and demagnetizes previous data. Next, move on to the return process, check the new data as it passes through the third magnetic head again, record a dummy signal in the low coercive force layer with the second magnetic head, and record the dummy signal with the first magnetic head. The feature is that the card is checked, taken out of the device, and returned to a magnetic card that can be prevented from being duplicated in the same way as before it was inserted into the device.

On the other hand, a leuco dye-based heat-sensitive coloring layer, a barrier layer and a protective layer are sequentially provided on the other side of the support, and at least one of these three layers contains zinc oxide and/or an ultraviolet absorber.

In this case, the ultraviolet absorber is, for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 4-dodecyloxy-2-hydroxy-4-methoxybenzophenone. , 2-hydroxy-4
- Benzophenone UV absorbers such as (hydroxy-3-methylacryloxy)propoxybenzophenone, 2-<2'-hydroxy-5-methoxyphenyl)
Benzotriazole UV absorbers such as benzotriazole, 2-(2-hydroxy-5-ethoxyphenyl)benzotriazole, phenylphenol, p-octylphenyl salicylate, p-tertiarybutylphenyl salicylate, carboxyphenyl salicylate, methyl Salicylic acid phenyl ester UV absorbers such as phenyl salicylate and dodecylphenyl salicylate, or p-methoxybenzylidene malonic acid dimethyl ester, 2-ethylhexyl-2-cyano-3,
3゛-diphenylacrylate, ethyl-2-cyano-
3,3′-diphenylacrylate, 3. Ditertiary butyl p-hydroxybenzoic acid, resorcinol monobenzoate which rearranges to benzophenone when exposed to ultraviolet light, 2',4'-ditertiary-butylphenyl-
In addition to solvent-dispersed types such as 3,5 ditertiary-butyl-4-hydroxybenzoate, 2-hydroxy-4-methoxybenzophenone-5-
2-hydroxy-4-methoxyhensiphenone-5-sulfonic acid
Nonolium sulfonate 2-hydroxy-4-methoxybenzophenone-5-
Sodium 2.2'-dihydroxy-4,4'-diphthoxybenzophenone-5-sulfonate Sodium 2.4-dihydroxybenzophenone-5-sulfonate 2.2'-dihydroxy-4,4'-diphthoxybenzophenone-5-sulfonate Sodium methoxybenzophenone-5,5'-disulfonate 2.4
-Dihydroxybenzophenone-5-Water-soluble benzophenone compounds such as sodium sulfonate, rutin, 2-7
Enylupenzimidazole-5-sulfonic acid alkali metal salts, p-cinnamoylaminobenzenesulfonic acid alkali metal salts, and the like are preferably used in the present invention.

Next, materials for the leuco dye-based heat-sensitive coloring layer, barrier layer and protective layer to which zinc oxide and/or ultraviolet absorber are added will be explained. The normally colorless or slightly light-colored leuco bodies used in the leuco dye-based thermosensitive coloring layer include the leuco bodies of triphenylmethane, fluoran, phenothiazine, auramine, and spiropyran dyes, and these include, for example, 3 .3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3.3-bis(p-dimethylaminophenyl)phthalide, 3.3-bis(p-dimethylaminophenyl)-6-
Dimethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3-(N-tolyl-N-ethylamino)-6-methyl-7-(N-phenylamino)fluoran, 2 -[3,6-bis(diethylamine)-9-(o-chloroanilino)xanthyl], benzoic acid lactam, and the like.

Examples of acidic substances that cause a thermochromic reaction with the leuco body and cause the leuco body to develop color include α-naphthol, β-naphthol, 4-t-butylphenol, and 4-t-butylphenol.
-octylphenol, 4-phenylphenol, 2.
2-bis(p-hydroxyphenyl)propane (also known as:
Bisphenol A), 2,2-(p-hydroxyphenyl)butane, 4,4″-cyclohexylidandiphenol, 2,2-bisque2,5-dibromo-4-hydroxyphenyl)propane, 4,4″-isopropylene Examples include derivatives of redene bis(2-t-butylphenol L2.2'-methylenebis(4-chlorophenol), benzoic acid, salicylic acid, tartaric acid, gallic acid, etc.), derivatives of bis(4-hydroxyphenyl)acetic acid ester, and the like.

The above-mentioned color-forming components are combined with a binder to form a heat-sensitive recording layer coating liquid, and the liquid is applied to the other side of a support having a magnetic recording layer on one side, and dried to form a heat-sensitive color-forming layer. .

Examples of the binder include the following.

Water-soluble ones such as polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, gelatin, etc.
Or an aqueous emulsion such as polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, etc.

Incidentally, additives such as fillers, lubricants, sensitizers, etc. that are commonly used in the heat-sensitive coloring layer may be used.

The barrier layer is for separating the protective layer made of a solvent-based paint from the heat-sensitive coloring layer, and is made of a generally known water-soluble resin.

The protective layer is applied to ensure the practical properties of the heat-sensitive recording layer, such as water resistance, plasticizer resistance, and chemical resistance. Various polymers are applicable.

<Example> Next, specific examples according to the present invention will be described.

A magnetic paint with the composition shown below is applied on a 250μ titanium oxide-kneaded polyester film as support 1! , n, I [
I was coated with a roll coater to a coating thickness of 5μ, 10μ, and 10μ in order and laminated to form a magnetic card.

Coating Formulation Example (2) On the other hand, a leuco dye-based coloring layer, a barrier layer, and a protective layer were sequentially coated and laminated on the other side of the support according to the following formulation to prepare a thermosensitive magnetic recording medium of the present invention.

[Leuco dye-based thermosensitive coloring layer]

A coating liquid was prepared by dispersing liquids A, B and C having the following formulations in a ball mill for 24 hours.

A solution B solution C solution 10 parts of the above solution A, 33.3 parts of solution B, 49 parts of solution C, ultraviolet absorber 2.2゛-dihydroxydiy4.4゛-diphthoxybenzophenone-5-sodium sulfonate 1 Department,
1 part of sodium dimethyldithiocarbamate, 20% diisobutylene-maleic anhydride ammonium salt aqueous solution as a binder (Olotane 165, manufactured by Rohm and Haas)
A heat-sensitive recording paint was obtained by mixing 15 parts and 46 parts of water. This coating material was applied to the other side of the support having the magnetic recording layer and dried to form a heat-sensitive layer with a coating weight of 6 glri.

[Barrier layer]

A coating liquid consisting of the following liquid is applied on the heat-sensitive coloring layer.It3g
/I to form a barrier layer.

Liquid D [protective layer] Furthermore, apply liquid E consisting of the following formulation on the barrier layer,
Dry coating amount 1g/n? A protective layer was formed to obtain a thermosensitive magnetic recording medium of the present invention.

Gap 30μ, track width 4m on magnetic card obtained with E liquid
A regular signal is recorded using a recording current of 700 mA and a recording density of 2108 PI using an FM magnetic head. Furthermore, a dummy signal is recorded using the above head at a recording current of 70 mA and the same <FM method recording density of 2108 PI.

As a result of reproducing this recorded magnetic card using the above-mentioned reading device, only the data of the 21013P I dummy signal could be read by the first head. This is because the signal recorded in the high coercive force magnetic layer is magnetically shielded by the high permeability magnetic layer, and its output is below the slice level of the reader. When this signal was demagnetized by the second head and read by the third head, the data of the 2108PI regular signal could be read. This requires a special DC auxiliary magnetic field.

Next, in order to duplicate this recorded magnetic card, a copy card with a coercive force of 3000e and a residual magnetic flux of 1.4Mx/
Using a 1.5 cm stickerless commuter pass, the magnetic surfaces of both cards were brought into close contact with each other by the contact method, and a 507 AC attenuation magnetic field of 1000 e was applied. As a result of reproducing the duplicated magnetic card with the above-mentioned reader, the output waveform of the 210 BPI dummy signal was modulated by the 2108 PI regular signal and could not be read by the first magnetic head.

When this signal was demagnetized by the second magnetic head and read by the third magnetic head, all the signals were erased and duplication was prevented.

On the other hand, the thermosensitive magnetic recording medium of the present invention was installed in a Sunshine Super Long Life Feather Meter (manufactured by Suga Test Instruments), and exposed in a dry state for 60 hours.
The density change due to photobleaching (by heating plate at ℃) was measured using a Macbeth densitometer. As a result, it was confirmed that the residual density of the colored part was 95% or more, and that it had extremely excellent light resistance. In addition, this heat-sensitive magnetic recording medium is applied to a ticket vending machine having a heat-sensitive recording mechanism to write predetermined magnetic information,
When the balance was displayed on the thermal recording surface at the same time as the reading, it was confirmed that there were no problems with implementation.

<Effects of the Invention> Since the present invention has the above-described configuration, it becomes impossible to easily detect a regular magnetic signal recorded on a thermosensitive magnetic recording medium, and counterfeiting by thermal transfer or contact transfer methods can be prevented.

In addition, it was confirmed that the heat-sensitive recording layer has extremely excellent durability in terms of practical properties such as light resistance even when used under harsh usage conditions by customers in applications such as cash coupons and commuter passes.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view in the width direction of the thermosensitive magnetic recording medium of the present invention, and FIG. 2 is a schematic diagram of the recording layer reading mechanism of the present invention. 11...Support 17...Barrier layer 12...High coercive force layer 18...
...Protective layer 13... High permeability magnetic layer 21.
...First magnetic head 14...Low coercive force layer 22...Second magnetic head 15...
・Protective printing layer 23...Third magnetic head 1
6... Leuco dye coloring layer 24... Fourth
Magnetic head patent requester Tomogawa Paper Mills Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] A high coercive force magnetic layer is provided on one side of the support, a high permeability magnetic layer and a low coercive force magnetic layer are sequentially laminated thereon, and a leuco dye-based thermosensitive coloring layer is provided on the other side of the support. In the heat-sensitive recording laminate comprising a layer, a barrier layer and a protective layer, at least one of the heat-sensitive coloring layer, the barrier layer and the protective layer contains zinc oxide and/or an ultraviolet absorber. A thermosensitive magnetic recording medium.