JP3429803B2 - Thermal recording type magnetic recording media - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] In a prepaid card used in a pay phone, a railway, a game, a store selling various articles, and the like, the usage status and the like are visually confirmed. In particular, the present invention relates to a magnetic recording medium on which visible information can be recorded using a thermal head, and more particularly to a thermosensitive recording magnetic recording medium in which the heat-sensitive recording layer has good storage stability. 2. Description of the Related Art Conventionally, a magnetic recording layer is provided on one side of a base material,
A thermosensitive recording magnetic recording medium in which a concealing layer, a thermosensitive recording layer containing a dye precursor and a color developing material as main components, and a protective layer are laminated in this order is well known (for example, JP-A-4-201).
396). In such a recording medium, as a concealing layer, a concealing metal powder such as a scale-like aluminum powder is dispersed in a resin binder to conceal the color of the magnetic recording layer,
It has been practiced to increase the contrast or sharpness of the visible information of the heat-sensitive recording layer. [0003] In order to produce scale-like metal powder such as aluminum powder, oleic acid or oleic acid is usually used as a pulverization aid in the pulverization step using a pulverizer such as a ball mill.
Use fatty acids such as stearic acid. [0004] Since these fatty acids exhibit a color developing effect on the dye precursor of the heat-sensitive recording layer, background fogging occurs during long-term storage and the like if they remain. To solve this problem, it is necessary to completely remove residual fatty acids used during the production of aluminum powder.However, aluminum powder is a metal powder having a large surface area and its surface activity is strong, so there is a danger of ignition. Yes, do not remove or replace with organic solvent. Another problem is that since aluminum powder has poor dispersibility, the packing density is not sufficiently increased, and sufficient hiding power cannot be obtained. Accordingly, an object of the present invention is to improve the quality of visible information (printing), prevent background fog under long-term storage and in a high-temperature and high-humidity environment, and improve the strength of a coating film of a concealing layer and an aluminum powder. The purpose of the present invention is to improve the cohesive strength of the coating film at the time of high filling, and to improve the printing contrast by increasing the concealment. According to the present invention, a magnetic recording layer, a concealing layer, a heat-sensitive recording layer containing a dye precursor and a color developing substance as main components, and a protective layer are provided on one surface of a substrate. sensitive recording type magnetic recording medium are laminated in this order, aluminum powder of the main component of the concealing layer, removing the fatty acid is a grinding aid
And then treated with at least one of a silane-based, titanate-based, and aluminum-based coupling agent. If necessary, a thermosensitive recording layer and a protective layer may be laminated in this order on the other surface of the base material to perform thermosensitive recording on both sides. The dye precursor in the heat-sensitive recording layer turns an acidic substance into a color developing substance to promote color development. When a heat-sensitive recording layer is provided on the magnetic recording layer side of a magnetic card, scaled aluminum powder is generally used because of its excellent hiding power, but many commercially available products are used in the manufacturing process. Oleic acid and stearic acid remain, exhibiting a color developing effect on the dye precursor as described above, and cause background fog. Therefore, these fatty acids may be removed. However, when the fatty acids are removed, the activity of the surface of the aluminum powder is strong, and there is a concern that ignition may occur due to oxidation or luminance may be reduced due to surface oxidation during storage of the aluminum powder. Therefore, the surface was organically coated with a silane-based, titanium-based, or aluminum-based coupling agent, which can be relatively easily treated in the manufacturing process, and stabilized. Also,
In the concealing layer coating film forming the concealing layer, the binding force between the binder and the aluminum powder is increased, the aluminum powder can be filled in a large amount, the concealing power is increased, and the printing contrast can be increased. Next, the present invention will be described in detail. In the present invention, as shown in FIG. 1, a magnetic recording layer 2, a concealing layer 3 containing a metal powder, and a heat-sensitive recording layer 4 containing a dye precursor and a color developing substance as main components are formed on one surface of a substrate 1. , And a protective layer 5 are laminated in this order on a thermosensitive recording type magnetic recording medium, and usually a printing layer is formed between the thermosensitive recording layer and the protective layer. Alternatively, as shown in FIG. 2, a heat-sensitive recording layer 6 and a protective layer 7 may be laminated in this order on the other surface of the substrate 1. Further, another layer may be provided if necessary. For example, by providing a primer layer between the concealing layer and the heat-sensitive recording layer, it is possible to secure chemical resistance, binding properties, and smooth contact with a thermal printer. Materials, thicknesses and forming methods usable as each layer of the recording medium of the present invention are as follows. (1) Material (a) Base material: polyethylene terephthalate, polycarbonate, vinyl chloride, paper, or a composite thereof. (B) Magnetic recording layer Magnetic material: barium ferrite, γ-iron oxide, iron, etc. Binder: polyurethane, vinyl chloride / vinyl alcohol / vinyl acetate copolymer, acrylic resin, nitrocellulose resin, polyester resin and blends thereof. Curing agent: Polymer such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate or polyisocyanate adducted with polyhydric alcohol. (C) Hidden layer aluminum powder: aluminum powder having a particle size of 5 to 20 μm, which is surface-treated with the following coupling agent.・ Vinyltriethoxysilane ・ Vinyltris (β-methoxyethoxy) silane ・ γ-methacryloxypropyltrimethoxysilane ・ γ-glycidoxypropyltrimethoxysilane ・ β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane N-β- (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ -Aminopropyltrimethoxysilane,-gamma-mercaptopropyltrimethoxysilane,-gamma-chloropropyltrimethoxysilane,-isopropyl triisostearoyl titanate,-isopropyl dodecylbenzenesulfonyl titanate,-isopropyl tris (dioctane) Le (phosphite) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate Titanate, ・ Isopropylisostearoyl diacryl titanate, ・ Isopropyltricumylphenyl titanate, ・ Isopropyltri (N-amidoethylaminoethyl) titanate, ・ Dicumylphenyloxyacetate titanate, ・ Diisostearoylethylene titanate, ・ Acetoxyalkoxy aluminum di Isopropylate. Binder: vinyl chloride resin, vinyl chloride / vinyl acetate copolymer, vinyl chloride / vinyl acetate / vinyl alcohol copolymer, acrylic resin, polyester resin, nitrocellulose resin, urethane resin, (d) heat-sensitive recording layer Examples of dye precursors (leuco dyes): crystal violet lactone, 3-diethylamino-7-cyclohexylaminofluoran, 3-diethylamino-6-methyl-7
-Anilinofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran, 3-diethylamino-7-chlorofuran, 3-diethylamino-6-methyl- 7-p-butylanilinofluoran, 3-diethylamino-5-methyl-7-tert-butylfluoran, 3-cyclohexylamino-6-chlorofluoran, 3-pyrrolidino-6-methyl-7-anilinofur Oran, 3-pyrrolidino-7-cyclohexylaminofluoran, 3-
Piperidino-6-methyl-7-toluidinofluoran,
3-piperidino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 2- (N- Phenyl-N-ethyl) aminofluoran, 2-anilino-3-methyl-6- (N-
Ethyl-p-toluidino) fluoran, 3- (N-methylcyclohexylamino) -6-methyl-7anilinofluoran. Developing substance: 4,4'-isopropylidene diphenol,
4,4′-isopropylidenebis (2-chlorophenol), 4,4′-isopropylidenebis (2-tert-butylphenol), 4-phenylphenol,
-Hydroxydiphenyl, 4,4'-benzylidenediphenol, 4,4'-thiobis (6-tert-butyl-3-methylphenol), 4,4'-secondarybutylidenediphenol, 4,4 '-(1 -Methyl-
Normal-hexylidene) diphenol, 4-hydroxyacetophenone, 4,4'-cyclohexylidenediphenol, 4,4'-cyclohexylidenebis (2-methylphenol), 4,4'-isopropylidenebis (2-methyl Phenol), 4,4'-ethylenebis (2-methylphenol), 4,4'-cyclohexylidenebis (2-isopropylphenol), methyl-4
-Hydroxybenzoate, phenyl-4-hydroxybenzoate, 2,2'-dihydroxyphenyl, 2,
2′-methylenebis (4-chlorophenol), 2,
2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-bis (4'-hydroxyphenyl) propane, 1,1'-bis (4-hydroxyphenol) -cyclohexane, phenol resin, bis (4-
Hydroxyphenyl) sulfone, 4-hydroxy-
4'-isopropyloxydiphenylsulfone, di-
(3-allyl-4-hydroxyphenyl) sulfone, binder: polyvinyl alcohol, methylene cellulose, hydroxyethyl cellulose, acrylic resin emulsion (e) protective layer UV-curable resin (ink), electron beam-curable resin (ink) (2) Thickness The thickness of each layer is preferably in the following range. Magnetic recording layer 10 to 15 μm Hiding layer 0.5 to 3 μm Thermal recording layer 2.5 to 6 μm Protective layer 0.5 to 2 μm (3) Manufacturing method Next, the following method can be used for manufacturing each layer. . Magnetic recording layer: Gravure, knife, bar, roll, comma coater or screen printing Concealment layer: Same as above Thermal recording layer: Same as above Protective layer: Offset printing Next, an embodiment of the present invention will be described. In the examples and comparative examples, the thickness of each layer was as follows. Magnetic recording layer 15 μm Concealing layer 2 μm Thermal recording layer 4 μm Protective layer 2 μm (Protective layer was cured by offset printing of UV curable ink with high pressure mercury lamp) Examples 1, 2, 3 (a) Base material 188 μm polyethylene terephthalate (E22 manufactured by Toray Industries, Inc.) (b) Magnetic recording layer Barium ferrite (MC127 manufactured by Toda Kogyo Co., Ltd.) 100 parts by weight Tripolymer of vinyl chloride / vinyl acetate / vinyl alcohol (Eslek A manufactured by Sekisui Chemical Co., Ltd.) 15 parts by weight Polyurethane elastomer (Nipporan 3113 manufactured by Nippon Polyurethane Industry Co., Ltd.) 60 parts by weight Curing agent (Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.) 20 parts by weight Methyl ethyl ketone 40 parts by weight Toluene 30 parts by weight The above composition was thoroughly mixed and dispersed. It was applied to the material and heat cured. (C) Aluminum powder (I) 20 parts by weight of aluminum paste (Alpaste 7640NS manufactured by Toyo Aluminum Co., Ltd.)
The mixture was stirred in a high-speed impeller for 30 minutes, and the aluminum powder was filtered out. After the same operation was performed 5 times, 3 parts by weight of isopropyl triisostearoyl titanate and 100 parts by weight of toluene were added, and the mixture was stirred at a high speed for 30 minutes, allowed to stand for 24 hours, and filtered to prepare aluminum powder I. (II) An aluminum powder II was prepared in the same manner as in (I) using acetoalkoxyaluminum diisopropylate. (III) Vinyl triethoxysilane was used in the same manner as (I): Aluminum powder III was prepared. (D) Concealing layer Aluminum powder 100 parts by weight Acrylic resin (Dianal BR50 manufactured by Mitsubishi Rayon Co., Ltd.) 30 parts by weight Methyl ethyl ketone 80 parts by weight Toluene 80 parts by weight The above aluminum powder was prepared by using aluminum powder I in Example 1, aluminum Example 2 uses powder II and Example 3 uses aluminum powder III. After dissolving the acrylic resin in methyl ethyl ketone and toluene, aluminum powder was added and the mixture was stirred with a high-speed impeller. (E) Thermosensitive recording layer A solution Fluoran leuco dye (TG-31 manufactured by Nippon Kayaku Co., Ltd.) 10 parts by weight Acrylic emulsion (Movinyl 730 manufactured by Hoechst Gosei Co., Ltd.) 20 parts by weight Water 5 parts by weight Solution B 4-hydroxy- 4 'isopropyloxydiphenyl sulfone 10 parts by weight Acrylic emulsion (Movinyl 730 manufactured by Hoechst Synthetic Co., Ltd.) 20 parts by weight Water 5 parts by weight Liquid A and Liquid B were mixed at a ratio of 1: 1 and mixed with a high-speed impeller. COMPARATIVE EXAMPLE 1 The aluminum powder of the embodiment was prepared by using Alpaste 7640NS.
What was stirred and filtered only once with toluene was used. Comparative Example 2 The aluminum powder of the example was treated with toluene five times, and was not treated with a coupling agent.
In Table 1, the evaluation of the strength of the coating film of the concealing layer was based on nails.
Scratches and those with few scratches by visual observation
The poor ones were marked as x. [Table 1] As is clear from Table 1, the scaled aluminum powder removes fatty acids such as oleic acid and stearic acid used in the production process, and is further treated with an organic metal coupling material. By doing so, the coating strength of the concealing layer is increased, and the storage characteristics are further improved. When the removal of the fatty acid was insufficient and the treatment was not performed with the coupling agent, the coating strength and storage characteristics of the concealing layer were poor (Comparative Example 1). Those which are not treated with the coupling agent even if the fatty acids are sufficiently removed do not cause fogging but have a weak coating film strength (Comparative Example 2). As described above, when the fatty acid is sufficiently removed and the surface is coated with an organic metal coupling agent and stabilized, the binding power between the binder and the aluminum powder in the concealing layer coating film forming the concealing layer increases, A large amount of aluminum powder can be filled, the hiding power can be increased, and the printing contrast can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view schematically showing the configuration of the present invention. FIG. 2 is a sectional view schematically showing another configuration of the present invention. [Description of Signs] 1 Base material 2 Magnetic recording layer 3 Concealment layer 4 Thermal recording layer 5 Protective layer 6 Thermal sensitive recording layer 7 Protective layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B42D 15/10 551 G11B 5/84 Z G06K 19/06 B41M 5/18 B G07F 7/08 G06K 19/00 B G11B 5/84 G07F 7/08 A

Claims (1)

(57) [Claims 1] A magnetic recording layer, a concealing layer,
In a thermosensitive recording magnetic recording medium in which a dye precursor and a color developing substance as main components, and a protective layer are laminated in this order, the aluminum powder as a main component of the concealing layer,
After removing the fatty acid as a grinding aid , at least one of a silane-based, titanate-based, and aluminum-based coupling agent is used.
A thermosensitive recording magnetic recording medium characterized by being treated with a seed.