JPH0775912B2 - Thermal magnetic recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermosensitive magnetic element that can be applied to ticket papers, commuter tickets, pass tickets and other cards, prepaid cards and other cards, and POS labels and other labels. It concerns a recording medium.

2. Description of the Related Art In recent years, magnetic cards such as magnetic coupons, road tickets, commuter passes, and prepaid cards have been remarkably popularized. In this case, it is required that the remaining amount display, the valid period of the card, the issue date, etc., which fluctuate every time the customer uses the card, can be recorded as visible information.

Examples of these recording means include printing, stamping, heat-sensitive transfer, heat-sensitive recording, and the like. However, a method of using a recording medium provided with a heat-sensitive recording layer is convenient because the apparatus is simple and maintenance-free. Has been done.

Conventionally, when this method is used, the heat-sensitive recording layer in the recording medium is generally provided on the other surface of the substrate provided with the magnetic recording layer because the magnetic layer is colored. However, recently, from the viewpoint of effective use of space, it has been required to provide the thermal recording layer on the same surface as the magnetic recording layer. In that case, it becomes necessary to provide a magnetic masking layer for masking coloring of the magnetic recording layer between the magnetic recording layer and the thermosensitive recording layer. Therefore, the recording medium in this case has a magnetic recording layer, a magnetic hiding layer, a thermosensitive coloring layer, and
It has a structure in which a first protective layer and a second protective layer are sequentially laminated.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, the thermosensitive magnetic recording medium having the above-mentioned configuration does not yet have sufficiently satisfactory characteristics, and the magnetic recording characteristics, thermosensitive recording characteristics, chemical resistance, water resistance, and the like are preserved. In terms of properties, the present situation is that a thermosensitive magnetic recording medium satisfying all of these characteristics has not yet been obtained.

The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a thermosensitive magnetic recording medium having a magnetic recording characteristic, a thermosensitive recording characteristic, and a sufficient storability in a layer structure in which a thermosensitive coloring layer is provided on the same surface as the magnetic recording layer.

Means for Solving the Problems The present invention has been completed as a result of studying a polymer compound applied to a binder of a magnetic concealing layer, a thermosensitive coloring layer, and a protective layer. The recording medium includes a magnetic recording layer, a magnetic concealing layer, a thermosensitive recording layer, and
It has a laminated structure in which a first protective layer and a second protective layer are sequentially laminated, and the magnetic hiding layer, the thermosensitive recording layer and the first protective layer each contain a polyester polyurethane resin,
The second protective layer is characterized by containing a resin selected from an acrylic resin, an ultraviolet curable resin and a polyurethane resin.

The present invention will be described in detail below.

In the present invention, the polyester polyurethane resin contained in the magnetic hiding layer, the thermosensitive coloring layer and the first protective layer comprises a polyester polyol composed of an acid component and a glycol component, a polyisocyanate and optionally a chain extender. It is obtained from.

Aromatic and aliphatic dicarboxylic acids are used as the acid component of the polyester polyol, but the aromatic dicarboxylic acid in the total acid component is preferably 70% by weight or more. Examples of aromatic dicarboxylic acids include terephthalic acid,
Examples thereof include isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, biphenylcarboxylic acid, and 1,2-bis (phenoxy) ethane-p, p'-dicarboxylic acid. As the aliphatic dicarboxylic acid, succinic acid, adipic acid, sebacic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4
-Cyclopentanedicarboxylic acid and the like.

As the glycol component of the polyester polyol, for example, ethylene glycol, propylene glycol, 1,3
-Propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, 1,4-cyclohexanediol, bisphenol A, hydroquinone and the like can be mentioned.

In synthesizing the polyester polyurethane resin used in the present invention, the polyester polyol is not necessarily 1
It is not necessary to use the same kind, and a plurality of polyester polyols may be mixed and used, but it is preferable that at least 60% by weight or more of the total polyester polyols contain the aromatic polyester polyol. The average molecular weight of the polyester polyol is preferably 80 to 4000, more preferably 1000 to 3000.

As the polyisocyanate which is a component of the polyester polyurethane resin used in the present invention, known polyisocyanates are used. For example, 2,4-tolylene diisocyanate,
2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,
4'-diphenylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, 1,4-cyclohexylene diisocyanate,
Examples include 3,3'-dimethyl-4,4'-biphenylene diisocyanate and 1,5-naphthalene diisocyanate.

The polyester polyurethane resin used in the present invention has a pendant carboxyl group of 0.5 in its structural composition.
It can be used as an aqueous binder by neutralizing the carboxyl group with ammonia and / or an organic amine in an amount of up to 6% by weight.

In this case, if the bendant carboxyl group is less than 0.5% by weight, it becomes difficult to make the aqueous solution, and if it is more than 6% by weight, the aqueous solution is easily made but the water resistance of the coating film is deteriorated. .

As a method of introducing a carboxyl group to obtain an aqueous polyester polyurethane resin having 0.5 to 6% by weight of a pendant carboxyl group used in the present invention, for example, when a polyester polyol is synthesized, a pendant carboxyl group-containing diol is used as a glycol component. And a method of using a chain extender containing a pendant carboxyl group as the chain extender.

In the present invention, when the polyester polyurethane resin is contained, an aziridine-based curing agent, an isocyanate-based curing agent or the like can be used as a curing agent.

Next, a description will be given of each layer structure constituting the thermosensitive magnetic recording medium of the present invention.

As the substrate in the thermosensitive magnetic recording medium of the present invention, a non-magnetic sheet-shaped or plate-shaped substrate is used. For example, high-quality paper, coated paper, art paper, synthetic paper, laminated paper, synthetic resin film, woven fabric sheet. , Metal, glass, and the like.

The magnetic recording layer provided on the substrate is not particularly limited as long as it has a composition that allows magnetic recording.
Generally, it is formed by applying or printing a coating material or ink in which magnetic powder is uniformly dispersed in a binder such as polyester resin, vinyl chloride resin, polyurethane resin or the like on a substrate. Here, as the magnetic powder, for example, γ-Fe ₂ O ₃ ,
Ferromagnetic materials such as barium ferrite and strontium ferrite are used, but in order to prevent the trouble that the magnetic recording information is erased or attenuated by a normal permanent magnet,
It is preferable to use a high coercive force material having a coercive force of 1500 to 5000 Oersted such as barium ferrite. For the purpose of preventing forgery, a high magnetic permeability layer such as Sendust or Permalloy, or a magnetic layer having a low coercive force of about 200 to 1000 oersteds such as iron oxide magnetic powder may be laminated in a plurality of layers.

The magnetic hiding layer is formed by uniformly dispersing a high hiding pigment in the polyester polyurethane resin,
It is provided on the magnetic recording layer by coating or printing. Examples of pigments having a high hiding property include aluminum paste and acidic titanium.

The heat-sensitive color-forming layer is composed of a binder containing a heat-sensitive color-developing system that develops color by heating. As the heat-sensitive color developing system, any known system can be applied. Hereinafter, representative examples of the heat-sensitive color-developing system will be described, but the present invention is not limited thereto.

(1) Leuco dye color development system The "NCR type" thermosensitive color development system develops a light color leuco dye with a color developer when heated. Examples of representative leuco dyes include crystal violet lactone, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3- Diethylamino-7-dibenzylaminofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-cyclohexylmethylamino-6-methyl- 7-anilinofluorane, 3-ethylisoamylamino-6-methyl-7-anilinofluorane, 3-diethylamino-7
(O-chloro alinino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane and the like can be mentioned.

Further, as the color developing agent which reacts with the above leuco dye under heat to develop a color, α-naphthol, β-naphthol, 4-t-
Butyphenol, 4-t-octylphenol, 4-phenylphenol, 2,2-bis (p-hydroxyphenyl) propane, 2,2- (p-hydroxyphenyl) butane, 4,4'-cyclohexylidenediphenol, 2 , 2-bis (2,5-dibromo-4-hydroxyphenyl) propane, 4,4'-isopropylidene bis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), 4,4 ′ -Sulfonyldiphenol, 4,4′-thiobisphenol, 4-hydroxyphenyl-4′-proxyphenyl sulfone, bis (4-hydroxy-3-allylphenyl) sulfone, bis (4-hydroxyphenyl) methyl acetate, bis Benzyl (4-hydroxyphenyl) acetate, novolac type phenol resin, benzoic acid, salicylic acid, tartaric acid, gallic acid, etc. Conductor, and the like.

(2) Light-fixing type diazo coloring system The "light-fixing" thermosensitive coloring system that has recently been put into practical use is
As a basic component, a photodecomposable diazonium salt and a coupler that forms a colored dye by a coupling reaction with the diazoium salt, and if necessary, a substance that increases the basic atmosphere during heating is added, and the present invention is applied. can do.

As the diazonium salt, coupler and basic substance used in this system, conventionally known ones are used.

(3) 3M-type color-developing system As a thermosensitive color-developing system of the "3M-type", it has been practically used as a thermal recording paper for a long time, for example, a combination of ferric stearate and tannic acid or gallic acid. A great many combinations of organic acid metal salts and color reaction reagents can be applied to the thermosensitive color developing layer of the present invention.

The above-mentioned typical thermosensitive coloring system requires at least two components to develop a color. Therefore, the constitution of the thermosensitive coloring layer includes a one-layer system containing all the components in one layer and a multi-layer system separating the components into two or more layers. A one-layer system is advantageous from the viewpoint of thermal color development sensitivity, but a multi-layer system is preferable in order to improve storage stability under high temperature and high humidity and for a long time.

In the present invention, the above polyester polyurethane resin is used as the binder in the thermosensitive coloring layer, but when the thermosensitive coloring layer is a multi-layer system rather than a one-layer system, a polyester polyurethane resin is used as the binder for at least one layer. It may be used. In particular, it is preferably used in a layer adjacent to the first protective layer. In this case, examples of the binder used in the other layer include vinyl chloride polymers such as vinyl chloride-vinyl acetate copolymer.

The first protective layer is provided to improve water resistance and is made of the above-mentioned polyester polyurethane resin.

The second protective layer is provided to improve the head matching property, and includes an acrylic resin, an ultraviolet curable resin,
The polyurethane resin is appropriately selected and configured.

As the acrylic resin, methyl acrylate, methyl methacrylate, acrylic acid, acrylamide, homopolymers or copolymers of acrylic mono-, such as acrylonitrile,
And copolymers of these acrylic monomers with monomers such as ethylene, vinyl chloride, vinyl acetate and styrene. Particularly preferred in the present invention is polymethylmethacrylate.

Examples of the UV curable resin contained in the second protective layer include UV curable resins utilizing photoradical polymerization such as vinyl group-containing monomers and oligomers. In particular, many types of oligoacrylates such as polyol acrylate, polyester acrylate, urethane acrylate, epoxy acrylate, polyacetal acrylate, and silicone acrylate can be applied. It is necessary for these resins to contain a photopolymerization initiator such as benzoin alkyl ether, benzophenone, benzyl, Michler's ketone, which generates radicals upon irradiation with ultraviolet rays. Further, an epoxy compound that undergoes ring-opening polymerization by a cation reaction with a Lewis acid catalyst can also be used as the ultraviolet curable resin. In this case, as the photoinitiator, an aromatic diazonium salt of Lewis acid, an aromatic halonium salt of Lewis acid, an aromatic sulfonium salt of Lewis acid, etc. are used, and by irradiation of ultraviolet rays, a Lewis acid is generated and the epoxy compound is polymerized. To do.

In the thermosensitive magnetic recording medium of the present invention, the thermosensitive coloring layer, the first
Alternatively, the second protective layer may contain inorganic and organic pigments as needed. For example, aluminum hydroxide, calcium carbonate, titanium oxide, barium sulfate, silica, activated clay, talc, clay, satin white, kaolinite, calcined kaolinite, diatomaceous earth, polyolefin particles, urea-formalin resin particles, fluorocarbon fine particles and the like. Can be included.

Further, in order to improve the thermochromic sensitivity and color density, for example, stearic acid amide, palmitic acid amide, oleic acid amide, lauric acid amide, and ethylenebis are added in the thermosensitive coloring layer and / or in a layer adjacent to the thermosensitive coloring layer. Stearoamide, methylenebis stearamide, methylol stearamide, paraffin wax, montanic acid wax, montanic acid ester wax, higher alcohol, etc. may be added. In addition to the above-mentioned pigments, the heat-sensitive coloring layer and the first or second protective layer may contain an aliphatic compound such as zinc stearate in order to prevent sticking and dust and to improve abrasion resistance. Lubricants such as metal salts, waxes, and fine particles of fluorocarbon can be contained.

In the thermosensitive magnetic recording medium of the present invention, the thickness of each of the layers sequentially laminated is 10 μm to 17 μm for the magnetic recording layer, 1.0 μm to 2 μm for the magnetic hiding layer, and 2.5 μm to 6 μm for the thermosensitive coloring layer.
It is preferable that m, the first protective layer and the second protective layer are each set in a range of 1 μm to 4 μm.

The thermosensitive magnetic recording medium of the present invention having the above-mentioned layer structure can be used for various purposes on the other surface of the substrate, that is, the other surface on which the magnetic recording layer, the magnetic concealing layer, the thermosensitive coloring layer and the like are not provided. It can be used for a wide variety of applications. For example, on the other surface, a predetermined display item,
In other words, it is possible to print the company name, notes, commercials and various mark patterns in black and white or color, or to provide a thermosensitive coloring layer and use it for a double-sided thermosensitive recording method to increase the amount of information recorded. is there.

EXAMPLES Next, the present invention will be described in detail with reference to Examples. In addition, all the parts representing the composition are parts by weight.

Example 1 A milk-white polyethylene terephthalate film having a thickness of 188 μm was sequentially coated with the following coating materials to form a layer having a film thickness shown in parentheses, to prepare a thermosensitive magnetic recording medium of the present invention.

(1) Paint for magnetic recording layer (coating thickness 13 μm) Barium ferrite 100 parts (Coercive force 3000 Oe average particle size 0.6 μm) Polyester resin 40 parts (Vylon 200: Toyobo Co., Ltd.) Carbon black 5 parts Lecithin 2 parts Methyl ethyl ketone 330 parts ( 2) Magnetic hiding layer coating (coating thickness 1.4 μm) Aluminum paste 33 parts (average particle size: 12 μm, solid content 60%) Polyester polyurethane resin 66 parts (Crisbon NT-810, solid content 30%; Dainippon Ink and Chemicals) Methyl ethyl ketone 34 parts Toluene 80 parts (3) Thermosensitive coloring layer coating (coating thickness 3 μm) 3- (ethylisoamylamino) -6-methyl-7-anilinofluorane aqueous dispersion (solid content 35%) 5.5 parts Aqueous dispersion of 4-hydroxyphenyl-4'-propoxyphenyl sulfone (solid content 30%) 18.5 parts Aqueous polyester polyurethane resin 18.5 parts (Hydran AP-40, solid content 23%: manufactured by Dainippon Ink and Chemicals, Inc.) Trimethylolpropane-tri-β-aziridinyl propionate 0.4 parts (4) Paint for first protective layer (coating thickness 1.4 μm) ) Polyester polyurethane resin 32.6 parts (Hydran AP-40, solid content 23%: manufactured by Dainippon Ink and Chemicals, Inc.) Trimethylolpropane-tri-β-aziridinyl propionate 0.4 parts Water 9 parts (5) Second protective layer Coating (coating thickness 1.6 μm) 100 parts of polyester acrylate (Aronix M8060; manufactured by Toagosei Kagaku Kogyo Co., Ltd.) 1- (4′-dodecylphenyl) -2-hydroxy-2
-Methylpropan-1-one photoinitiator 5 parts (Dulcure 953, manufactured by MERCK) Polyethylene wax 5 parts Silicone oil 1 part In addition, the drying of the second protective layer after applying the UV curable coating is 1.2K.
w Using an ultraviolet curing device consisting of one mercury lamp, irradiation was performed with ultraviolet rays at a distance of 10 cm from the lamp and a conveying speed of 15 m / min.

Example 2 250 μm thick polypropylene-based synthetic paper (YUPO base paper FPG25
0; manufactured by Oji Yuka Synthetic Paper Co., Ltd.) was provided with the magnetic recording layer and the magnetic masking layer described in Example 1. Then, the following coating materials were sequentially laminated and coated to form a layer having a film thickness shown in parentheses, to prepare a thermosensitive magnetic recording medium of the present invention.

(1) Paint for thermosensitive coloring layer (coating thickness 3 μm) 3- (butylamino) -7- (0-chloroanilino) fluorane aqueous dispersion (solid content 35%) 5.5 parts Bis- (4-hydroxy-3-allyl) Aqueous dispersion of phenyl) sulfone (solid content 30%) 18.5 parts Aqueous polyester polyurethane resin 14.2 parts (Hydran AP-40, solid content 30%; Dainippon Ink and Chemicals, Inc.) Trimethylolpropane-tri-β-aziridini Lepropionate 0.4 parts (2) First protective layer paint (coating thickness 1.4 μm) Water-based polyester polyurethane resin 24.9 parts (Hydran AP-10, solid content 30%: Dainippon Ink and Chemicals Incorporated) Trimethylolpropane- Tri-β-aziridinyl propionate 0.4 parts Water 16.7 parts (3) Second protective layer coating (coating thickness 1 μm) Acrylic resin 33 parts (Thermolac M-2000, solid content: Soken Chemical Industry Co., Ltd. ) Fluorocarbon dispersion 10 parts (MOLD WIZ F-57, solid content 8%: manufactured by Toyo Soda Kogyo Co., Ltd.) Toluene 5 parts Comparative Example I All examples except that the magnetic hiding layer coating material of Example I was replaced with the following A thermal magnetic recording medium for comparison was prepared in the same manner as in I.

Magnetic hiding layer coating (coating thickness 1.4 μm) Aluminum paste 33 parts (average particle size: 12 μm, solid content 60%) Polyester resin 20 parts (Vylon 200: Toyobo Co., Ltd.) Methyl ethyl ketone 80 parts Toluene 80 parts Comparative Example 2 Example The water-based polyester polyurethane resin in the heat-sensitive color developing layer paint of 2 is a water-based polyester resin (Finetex
ES-675, solid content 37%: Dainippon Ink and Chemicals, Inc.) 11.
All were the same as in Example 2 except that 5 parts were used.

With respect to the thermosensitive magnetic recording media of Examples 1 and 2 and Comparative Examples 1 and 2 described above, the magnetic characteristics were measured using the ticket issuing device for high coercive force magnetic cards, and all were satisfactory.

The results of other characteristics are shown in Table 1.

The methods for measuring and evaluating the properties in the table are shown below.

<Dynamic color development characteristics> 0.45W (1mJ / dot) using line dot type thin film thermal head
An image was recorded with the energy of, and the solid black portion was measured with a visual filter of a Macbeth densitometer.

<Water resistance> After immersion in tap water for 1 week, the following gate resistance test is performed.

Gate resistance test Pass a ticket-shaped test piece 3000 times through the automatic ticket gate in the same way, and inspect it for scratches, peeling and dirt on the recording surface.

◯: Almost no scratches, peeling or stains are seen.

Δ: At least one of scratches, peeling, and dirt is slightly seen.

X: Are there two or more phenomena of scratches, peeling, and dirt?
Even if only one is large.

As is clear from Table 1, it was confirmed that the thermosensitive magnetic recording medium of the present invention maintained excellent dynamic color development characteristics and also had excellent water resistance.

EFFECTS OF THE INVENTION As described above, the thermosensitive magnetic recording medium of the present invention has a magnetic recording layer, a magnetic concealing layer, a thermosensitive coloring layer, a first protective layer and a second protective layer on a substrate.
In the laminated structure in which the protective layers are sequentially laminated, since the polyester polyurethane resin is used as a binder in the magnetic hiding layer, the thermosensitive coloring layer, and the first protective layer,
It is possible to remarkably improve water resistance while maintaining excellent magnetic and heat-sensitive properties. Therefore, the thermosensitive magnetic recording medium of the present invention has extremely excellent properties in terms of magnetic properties, thermosensitive properties, and storability, and can be effectively utilized for various purposes such as ticket papers and cards. .

Front page continued (72) Inventor Masayasu Suzuki No. 3 Munebacho, Shizuoka City, Shizuoka City, Ltd., Technical Research Institute, Tomagawa Paper Mill Co., Ltd. No. 3 in the Technical Research Laboratory, Tomoegawa Paper Mill Co., Ltd. Koichi Aoyama 3-1, Soba-cho, Shizuoka City, Shizuoka Prefecture (56) In the Technical Research Laboratories, Tomoegawa Paper Mill (JP) 52-114333 (JP) , A) JP 59-199285 (JP, A) JP 62-290579 (JP, A)

Claims (1)

[Claims] 1. A magnetic recording layer, a magnetic concealing layer, a thermosensitive coloring layer, a first protective layer and a second protective layer are laminated in this order on a substrate, and the magnetic concealing layer, the thermosensitive coloring layer and the A thermosensitive magnetic recording medium, wherein the first protective layer contains a polyester polyurethane resin, and the second protective layer contains a resin selected from an acrylic resin, an ultraviolet curable resin and a polyurethane resin.