JP4534576B2 - Magnetic recording medium - Google Patents

Description

  The present invention relates to a magnetic recording medium composed of a magnetic recording layer using a binder resin not containing chlorine atoms, and more particularly to magnetic recording used for the manufacture of a magnetic recording medium for a passbook used for bank passbooks, postal savings passbooks, etc. It relates to the medium.

  A nonmagnetic support; a magnetic recording layer formed on one surface of the nonmagnetic support; and an adhesive layer formed on a surface of the nonmagnetic support opposite to the surface on which the magnetic recording layer is formed. A magnetic recording medium constituted by: Such a magnetic recording medium is attached to, for example, a part or the whole of one or both sides of a front cover or a back cover of a paper booklet. As a specific example of the booklet, there is a bankbook for use details recording such as a bankbook or a postal savings bankbook.

  In recent years, such a passbook magnetic recording medium has been used to deal with demagnetization accidents in which recorded information on the magnetic recording medium is erased by a permanent magnet used for a handbag clasp, etc., and to increase the recording density and S / N of the magnetic recording medium. The magnetic powder has become higher coercive force in response to demands for improving the ratio and C / N ratio, so it is more necessary to obtain a magnetic recording layer having a high degree of filling by uniformly dispersing the magnetic powder in the paint. It has become. For this reason, the dispersing ability of the binder resin for uniformly dispersing the magnetic powder was a very important factor.

  By the way, when a magnetic recording medium is formed by a coating technique, the magnetic properties are usually improved by a method called orientation. Orientation is to align the easy axis of magnetization of magnetic powder in one direction by passing it through a magnetic field in a state in which sufficient fluidity remains after the magnetic paint is applied. The purpose of orientation is to improve the squareness ratio (Br / Bm), thereby improving the residual magnetic flux density (Br), increasing the signal energy recorded by the magnetic head, and consequently improving the reproduction output. That is.

  In order to achieve sufficient orientation, not only the magnetic powder is uniformly dispersed, but also the orientation of the magnetic powder must be maintained after orientation. Among known and commonly used magnetic powders, there are powders having a very large particle diameter and a disk shape, such as barium ferrite. Barium ferrite is flat and has an easy magnetic axis in the vertical direction and is excellent in short wavelength recording characteristics. However, since the particle diameter is large, the structure aligned in the easy magnetization axis direction tends to be disturbed after orientation. Although it is important to maintain the structure after this orientation until it passes through the drying path of the magnetic layer, in order to realize this, it is necessary to use a vinyl chloride resin as a binder resin. It has been difficult to solve the above problems with a resin.

  Also in a magnetic recording medium for a booklet such as a passbook, a vinyl chloride copolymer has generally been used from the viewpoint of high dispersibility of magnetic powder and cost. However, vinyl chloride copolymers have recently been used due to the generation of toxic hydrogen chloride gas during landfill disposal and the generation of harmful dioxins during low temperature combustion when incinerated. There is a tendency to avoid doing. Most booklets are made of paper and do not contain chlorine, but vinyl chloride copolymers are still used in the magnetic stripes and printing inks of the booklets, making the booklet completely free of chlorine. Absent. Although the amount of resin used for magnetic stripes is small, there is a report that the amount of chlorine during incineration and the amount of dioxin generated is not proportional, so even if only a small amount of chlorine compound is contained during incineration. There is also the possibility of generating problematic amounts of dioxins. For this reason, it has been desired to completely dechlorinate the magnetic recording medium to be attached to a booklet or the like.

  As a technique aimed at devinylation of magnetic recording media for use in booklets, etc., a radically polymerizable monomer having a hydrophilic polar group was copolymerized as a binder resin for the magnetic recording layer. A technique containing an acrylic resin and a polyurethane resin is disclosed (see Patent Document 1), and a technique related to a magnetic recording medium for cards using a similar technique is disclosed (see Patent Document 2). Furthermore, as a binder resin, a styrene copolymer or an acrylic resin containing at least one hydrophilic group selected from a salt-type strong acid group containing sulfur or phosphorus and a quaternary ammonium base and an epoxy group Has disclosed a magnetic recording medium (see Patent Document 3).

  However, with the technologies disclosed in these prior arts, it is possible to obtain a magnetic recording medium having excellent magnetic properties by completely de-vinylating the magnetic recording layer and further realizing the dispersibility of barium ferrite magnetic powder. It was difficult.

JP 2002-56524 A JP 2000-31330 A JP-A-5-182176

  Accordingly, an object of the present invention is to provide a magnetic recording medium using a non-vinyl chloride resin having good dispersibility of barium ferrite powder and excellent magnetic properties. Another object of the present invention is to provide a booklet using a magnetic recording medium that solves the above problems. Another object of the present invention is to provide a passbook using a magnetic recording medium that solves the above problems.

As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the binder resin is a resin having a molecular structure that does not have a chlorine atom, and a monomer having a hydrophilic polar group in the molecule. Even when barium ferrite powder is used as magnetic powder, the dispersibility of the powder is good by using an acrylic resin copolymerized with a radically polymerizable monomer containing 30 to 40% by mass relative to the body. The inventors have found that a magnetic recording medium having excellent magnetic properties can be obtained, and have completed the present invention.
That is, the present invention provides a nonmagnetic support, a magnetic recording layer formed on one surface of the nonmagnetic support, and a surface of the nonmagnetic support opposite to the surface on which the magnetic recording layer is formed. A magnetic recording medium composed of an adhesive layer formed on
The magnetic recording layer is a layer in which barium ferrite powder is finely dispersed in a binder resin containing an acrylic resin, and the acrylic resin has a total amount of monomers having hydrophilic polar groups in the molecule. Provided is a magnetic recording medium characterized in that it is a resin obtained by copolymerizing a radically polymerizable monomer containing 30 to 40% by mass with respect to the body, and has a structure having no chlorine atom in the molecule. To do.
The present invention also provides a booklet using the magnetic recording medium. Furthermore, the present invention provides a passbook using the above magnetic recording medium.

  Since the magnetic recording layer of the magnetic recording medium of the present invention uses the above binder resin, the dispersibility of the barium ferrite particles is good, and the orientation structure of the barium ferrite particles immediately after coating is the magnetic recording layer. It is maintained even immediately after the formation. Therefore, the magnetic recording medium of the present invention exhibits an excellent squareness ratio and is a magnetic recording medium having a high reproduction output. In addition, since the magnetic recording medium of the present invention does not contain a chlorine compound in the composition, toxic hydrogen chloride gas is generated at the time of landfill disposal, or harmful dioxins are generated when attempting to incinerate. There is no.

  The magnetic recording medium in the present invention is a medium in which a laminate including at least a magnetic recording layer is formed on a nonmagnetic support, and an adhesive layer such as an adhesive is formed on the opposite side across the support. It is a generic term for media used in the manufacture of magnetic recording media such as passbooks with magnetic stripes, which are attached to other substrates together with the body. There are various forms of magnetic recording media, such as sheets and tapes.

Hereinafter, the present invention will be described in detail.
The binder resin used in the magnetic recording layer of the magnetic recording medium of the present invention has a structure having no chlorine atom in the molecule and a monomer having a hydrophilic polar group in the molecule with respect to all monomers. It is a resin containing an acrylic resin copolymerized with a radically polymerizable monomer containing 30 to 40% by mass. In addition, other resins can be used as needed as long as they do not impair the effects of the present invention, but even in that case, the resin may have a structure having no chlorine atom in the molecule. preferable. Examples of the radical polymerizable monomer having a hydrophilic polar group used for producing the acrylic resin used in the present invention include a monomer having a hydroxyl group, a carboxyl group, a sulfonic acid group, or a phosphate group. Is mentioned.

Examples of monomers having a hydroxyl group include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol polypropylene glycol mono (meth) acrylate, Glycerol mono (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, allyl hydroxyethyl ether, allyl hydroxypropyl ether, allyl hydroxybutyl ether, allyl hydroxyethoxyethyl Ether, allyl hydroxypropoxypropyl ether, allyl dihydro Shi propyl ether, allyl 3-chloro-2-hydroxypropyl ether, vinyl alcohol, allyl alcohol, and the like. In the present specification, (meth) acrylic acid means acrylic acid or methacrylic acid, and the same applies to derivatives of acrylic acid or methacrylic acid.
Among them, as a monomer having a hydroxyl group used in the present invention, the following formula (I)

（式中、Ｒ_１は水素原子又はメチル基を表し、Ｒ_２は分岐鎖を有していても良い炭素原子数２〜８のアルキレン基を表す。）で表される化合物を使用することが好ましい。特に、２−ヒドロキシエチル（メタ）アクリレートを使用することが好ましい。

(Wherein R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkylene group having 2 to 8 carbon atoms which may have a branched chain). preferable. In particular, it is preferable to use 2-hydroxyethyl (meth) acrylate.

  Examples of the monomer having a carboxyl group include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride, and dibasic acids. Examples include half esters.

  Examples of the monomer having a sulfonic acid group include compounds having the following structural formula.

（ただしＭは水素原子またはアルカリ金属原子を表し、Ｒはアルキル基を表す。）等が挙げられる。

(Wherein M represents a hydrogen atom or an alkali metal atom, and R represents an alkyl group).

  Examples of monomers having a phosphate group include mono [(meth) acryloyloxyethyl] acid phosphate, mono [(meth) acryloyloxypropyl] acid phosphate, mono [(meth) acryloyloxybutyl] acid phosphate, mono [( (Meth) acryloyloxyethoxynoethyl] acid phosphate, mono [(meth) acryloyloxypolyoxyethylene glycol] acid phosphate, (meth) acryloyloxyethyl methyl acid phosphate, (meth) acryloyloxyethylbutyl acid phosphate, (meth) acryloyl Oxypropyl ethyl acid phosphate, (meth) acryloyloxyethyl methyl acid phosphate, (meth) acryloyloxy polyoxyethylene glycol Butyl acid phosphate, and vinyl acid phosphate and alkali metal salts thereof and the like.

  The radically polymerizable monomer having a hydrophilic polar group may be used alone or in combination of two or more. However, if the amount is too small, the dispersibility is lowered. Get higher. Accordingly, the amount of the radical polymerizable monomer having a hydrophilic polar group is 30 to 40% by mass, preferably 32 to 38% by mass, based on the total monomers.

  The acrylic resin used in the present invention is an acrylic resin produced using the radical polymerizable monomer having the hydrophilic polar group described above, but other acrylic monomers are methyl. Methacrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, benzyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) Alkyl (meth) acrylates such as acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, and alkoxyalkyl (meth) such as methoxyethyl (meth) acrylate and butoxyethyl (meth) acrylate It can also be used, such as acrylate compounds.

  Moreover, radically polymerizable monomers other than the above can be copolymerized as needed. Examples of such monomers include vinyl acetate, vinyl propionate, styrene, ethylene, propylene, butylene, isobutylene, butadiene, methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, n-butyl vinyl ether, 2-ethylhexyl vinyl ether, Examples thereof include alkyl vinyl ethers such as n-octyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether and stearyl vinyl ether. These monomers can be used in an amount of 20% by mass or less of the total amount of the monomers as long as the effects of the present invention are not impaired, and the optimum amount used is the glass transition temperature and strength of the resulting copolymer, Young's modulus. It is selected in consideration of physical properties such as interlayer adhesion at the time of multilayer coating.

  Copolymers composed of combinations of the monomers described above have low physical strength, such as the magnetic coating becoming brittle if the molecular weight is too low, and the durability at the time of card formation after thermal transfer is also reduced. To do. On the other hand, if the molecular weight is too high, the viscosity of the coating material for forming the magnetic layer is increased, the workability at the time of application is deteriorated, and handling becomes difficult. For this reason, it is preferable that the number average molecular weights are 1000-100000, More preferably, it is the range of 5000-20000. Moreover, it is preferable that the mixture ratio of said acrylic resin is 20-70 mass% of all the binder resin, More preferably, it is 40-60 mass%.

  As the binder resin used for the magnetic recording layer of the magnetic recording medium of the present invention, it is preferable to use together with an acrylic resin, a polyurethane resin having no chlorine atom in the molecular structure. Polyurethane resin exhibits good properties in terms of mechanical properties such as surface hardness and adhesive strength of the magnetic recording layer. Especially when used in combination with the acrylic resin, which has excellent dispersibility of magnetic powder, a well-balanced magnetic recording layer is formed. Form.

  If the mass ratio of the acrylic resin and the polyurethane resin is 1:10 or more, the balance between the dispersion of the magnetic powder in the magnetic recording layer and the physical properties of the magnetic recording layer can be suitably maintained. In particular, blending in the range of 2: 5 to 3: 2 is preferable in terms of production efficiency.

  The binder resin for the magnetic recording layer may be used in combination with other resins as required. Examples of resins that can be used in combination include binder resins that do not contain chlorine in the molecular structure, such as polyester, nitrocellulose, and epoxy resins. And various resins such as polymers or copolymers such as phenol resins, cellulose derivatives, alkyd resins, and polyvinyl butyral resins.

  The content of the polyurethane resin having no chlorine atom in the molecular structure is preferably 30 to 80% by mass and more preferably 40 to 60% by mass with respect to the total binder resin of the magnetic recording layer.

The magnetic powder used in the present invention is barium ferrite, and the particle diameter of the barium ferrite particles is preferably 0.5 to 1.0 μm, more preferably 0.6 to 0.9 μm. Further, the BET specific surface area is preferably ² to 9 m ² / g, more preferably 3 to 8 m ² / g. The particle diameter is a value measured by the aeration method.

  The magnetic coating material for producing the magnetic recording layer can be obtained, for example, by kneading and dispersing a barium ferrite powder, a binder resin, an organic solvent, and other components as necessary with a kneading and dispersing machine.

  Examples of organic solvents include ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone, ester solvents such as methyl acetate, ethyl acetate, and butyl acetate, and alcohol solvents such as methanol, ethanol, and propanol. Solvents, hydrocarbons such as hexane, benzene, toluene, xylene, etc., ether solvents such as glycol dimethyl ether, glycol monoethyl ether, dioxane, tetrahydrofuran, etc. can be mentioned, and these solvents are used by mixing two or more types You can also

  Various kneading and dispersing machines can be used for kneading and dispersing for producing the magnetic paint. Examples of the kneading and dispersing machine include a two-roll mill, a three-roll mill, a ball mill, a pebble mill, a Henschel mixer, a cobol mill, a tron mill, a sand mill, a sand grinder, a seg barrier striker, a high-speed impeller disperser, a high-speed stone mill, and a high-speed impact mill. , Disperser, high-speed mixer, homogenizer, ultrasonic disperser, open kneader, continuous kneader, pressure kneader and the like.

  The coating method of the magnetic paint is not particularly limited, and a known coating method may be used, which can be manufactured according to a method used for manufacturing a magnetic recording medium having a single layer or a plurality of layers. Gravure method, reverse method, air doctor coater method, blade coater method, air knife coater method, squeeze coater method, impregnation coater method, transfer roll coater method, kiss coater method, cast coater method, spray coater method, die method and the like can be used.

  As a method for orienting the barium ferrite powder, a known method, for example, a repulsive counter permanent magnet or a solenoid type electromagnet can be used. The magnetic field strength is preferably in the range of 1000 to 6000G.

  FIG. 1 shows a schematic view of a passbook with a magnetic stripe which is one embodiment of the present invention, and FIG. 2 shows a magnetic label laminate (with a nonmagnetic layer for concealment) as a magnetic recording medium for forming a magnetic stripe for a passbook. 3 is a cross-sectional view of a magnetic stripe portion of a passbook with a magnetic stripe (with a nonmagnetic layer for concealment) formed using the magnetic label laminate. Hereinafter, each component will be described in detail with reference to these drawings.

  As the passbook base A, for example, a cloth paper for magnetic passbook, which is coated with a resin coating having a good surface smoothness using a cloth cloth as a base cloth, or the like is used. Using this substrate A as the cover of a booklet, a magnetic stripe B, which is a laminate including a magnetic recording layer, is formed on one or both of the front cover and the rear cover, or on the entire surface.

  Next, each constituent material of the magnetic stripe part of the passbook with a magnetic stripe or each constituent material of the magnetic recording medium for bonding used in the production through the bonding process of the passbook will be described in detail.

  The passbook base 7 is generally designated to use the above-mentioned cross paper for magnetic passbook, but the surface is applied with a resin coating that is suitable for attaching magnetic stripes and has good surface smoothness. Magnetic passbook cloth paper, etc. is used. Especially, the surface roughness of the magnetic stripe application surface (cross paper) is preferably 20 μm or less in terms of the center line average surface roughness (however, from the viewpoint of magnetic stripe application strength) 15 μm or less is more desirable).

  On the other hand, the structure of the magnetic label laminate used for the manufacture of a magnetic recording medium such as a passbook with a magnetic stripe by the attaching process (bonding process) is magnetic on one surface of the magnetic label substrate 1 as shown in FIG. The recording layer 2 is formed, and the protective layer 4 (when there is no colored layer) is formed thereon. Further, an adhesive layer (adhesive layer) 5 is provided on the other surface of the magnetic label substrate 1. On the pressure-sensitive adhesive layer, usually a release paper 6 that is a base for a magnetic label is bonded.

  In addition, from the viewpoint of improving aesthetics and design, a colored layer 3 or a pattern layer that conceals the hue of the magnetic recording layer may be provided between the magnetic recording layer 2 and the protective layer 4.

  Usually, such a laminated structure of a magnetic recording medium for bonding such as a magnetic label laminated body is formed by layering on a film-like magnetic label substrate and coating each constituent layer.

  Thereafter, the original fabric is cut into a sheet, and in some cases, the magnetic label laminate is cut from the original fabric or sheet into a desired size by a method such as slitting or punching. Moreover, the tape-shaped slit of the magnetic recording medium for bonding can be performed from a raw fabric or the said sheet | seat, and it can also be used as a tape for magnetic labels. When affixing to the bankbook base, the magnetic label laminate including the magnetic recording layer 2 is superimposed on the bankbook base 7 via the adhesive layer 5, and pressure and heat are applied to the bankbook base. To form a magnetic stripe B

  Next, regarding the magnetic label laminate, various constituent materials used other than the magnetic recording layer will be described in detail.

  Any known magnetic label substrate 1 that can be used for a magnetic recording medium such as a magnetic label laminate can be used. Examples thereof include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and plastics such as polyamide and polycarbonate. Of these, polyethylene terephthalate having both tensile strength and heat resistance is preferred.

  The thickness of the magnetic label substrate 1 is not particularly limited, but is usually 10 to 100 μm, preferably 20 to 80 μm.

  Next, the colored layer 3 may be applied to conceal the color of the magnetic recording layer 2 and to improve the decorativeness of the passbook itself. Further, a pattern layer may be applied to improve the decorativeness of the passbook itself.

  The colored layer 3 important for concealment may have a single layer structure or a multilayer structure. As inorganic pigments used in the colored layer, alumina, titanium oxide, chromium oxide, iron oxide, zinc oxide, barium sulfate, etc., as organic pigments, azo pigments, benzimidazolone pigments, phthalocyanine pigments, quinacridone pigments, There are many perylene pigments, perinone pigments, anthraquinone pigments, thioindigo pigments, indanthrene pigments, but there is no particular limitation.

  In order to form the colored layer 3, a pigment is mixed singly or in combination of two or more in a binder resin, and dispersed by a known method to prepare a coloring coating solution, which is applied by a known method. The colored layer 3 can be formed by, for example, applying and printing a printing ink containing a pigment, a resin binder, and a solvent that dissolves the resin binder. As a method for forming the colored layer 3, there are known printing methods such as gravure printing, flexographic printing, offset printing, and screen printing.

  First, the magnetic recording layer 2 is formed on the substrate by the above-described method, and then the colored layer 3 is used to conceal the magnetic color of the magnetic recording layer 2 and to improve the decoration of the passbook itself. Apply. If the pattern layer or the colored layer 3 is too thin, the magnetic color of the magnetic recording layer 2 cannot be concealed, and if it is too thick, the reproduction output decreases due to spacing loss. For this reason, it is usually used in the range of 0.5 to 20 μm.

  Further, as a method for concealing the magnetic color of the magnetic recording layer 2 more effectively, a metal vapor-deposited film can be provided between the magnetic recording layer 2 and the colored layer 3, and aluminum, tin, gold, silver, platinum, etc. A metal vapor deposition layer can be used. If this method is used, it is possible to conceal the magnetic color with a thinner film thickness than in the case of coating film formation by applying a coloring paint, and it is possible to prevent deterioration of characteristics such as output and resolution. The range of the film thickness used as the metal vapor deposition film is usually 0.05 to 0.1 μm.

  Furthermore, after providing the magnetic recording layer 2 and the colored layer 3 in this order on the magnetic label substrate 1, a protective layer 4 that is also a layer having a function of surface protection can be provided as the outermost layer of each formed layer. The substance constituting the protective layer 4 is preferably a material having high durability and heat resistance because it receives heat and pressure when bonded to the passbook substrate 7. For example, cellulose-based resin, polyvinyl butyral resin, epoxy resin And phenol resins, polyester resins, polyurethane resins, acrylic resins, polymethyl methacrylate and copolymers thereof, melamine resins, and the like, and mixtures of these resins.

  Furthermore, soybean lecithin, a phthalic acid plasticizer, microsilica, wax, or the like can be added to the protective layer 4 as a film modifier as necessary. The protective layer 4 is formed, for example, by applying a paint obtained by dissolving and dispersing the above constituent substances in a solvent on the magnetic recording layer 2 or the colored layer 3 by a known method.

  On the other hand, when the magnetic label laminate is bonded to the passbook, the adhesive layer 5 which is an adhesive layer provided on the side opposite to the magnetic recording layer 2 on the magnetic label laminate is first placed at a predetermined temperature on the passbook substrate 7 at room temperature. Then, it is heated at a temperature of about 120 ° C. and pressed to further strengthen the adhesion. Therefore, the pressure-sensitive adhesive layer 5 provided on the surface opposite to the magnetic recording layer 2 of the magnetic label substrate 1 is desirably a pressure-sensitive pressure-sensitive adhesive having excellent adhesive force both at the time of room temperature pressure bonding and after heating and pressing. A release paper 6 is usually attached adjacent to the pressure-sensitive adhesive layer 5.

  Examples of the pressure-sensitive adhesive resin used for the pressure-sensitive adhesive layer 5 include a copolymer of alkyl acrylate and (meth) acrylic acid, a copolymer of alkyl acrylate, (meth) acrylic acid and vinyl acetate. A vinyl chloride resin such as a polymer or a copolymer further added with vinyl alcohol, maleic anhydride or acrylic acid, a polyester resin, an acrylic resin, a polyimide resin, a polyurethane resin, a phenol resin, or the like can be given.

  Furthermore, by adding a cross-linking agent to the resin composition, it is possible to control the adhesive strength at the time of room temperature pressure bonding and the adhesive strength after heating. As this crosslinking agent, those conventionally used for pressure-sensitive adhesives can be used, and specific examples include isocyanate-based crosslinking agents, amine-based crosslinking agents, and epoxy-based crosslinking agents.

  The pressure-sensitive adhesive layer coating that can be used for the pressure-sensitive adhesive layer 5 is prepared by dissolving a resin exhibiting pressure-sensitive adhesiveness in a solvent at a ratio of 3 to 20% by mass with respect to the resin to the solvent, and mixing and stirring. And adjust. For the application of the pressure-sensitive adhesive layer 5, a publicly known application method described in the magnetic recording layer 2 can be used. The range of the thickness of the pressure-sensitive adhesive layer is usually 5 to 100 μm.

  As a magnetic recording medium, usually, an adhesive layer made of an adhesive layer 5 or the like is formed in advance on the surface opposite to the magnetic recording layer 2 of the magnetic label substrate 1, but this adhesive layer is not formed, and a substrate such as a passbook is used. An adhesive layer may be separately formed on the side of the substrate by application or the like, and bonded using a magnetic label laminate having no adhesive layer.

  In order to create a passbook with a magnetic stripe using the magnetic label laminate formed in this manner, a magnetic recording medium original sheet or sheet is cut into a predetermined width once and then created. A method is used in which a label tape is prepared and cut and used as a label, or a part used for a magnetic stripe is directly punched out from the original or sheet into an island shape and used as a label. .

  After that, as described above, the pressure-sensitive adhesive layer 5 provided on the magnetic label laminate is first crimped to a predetermined portion of the passbook substrate 7 at room temperature, and then heated and pressurized at a temperature of about 100 to 120 ° C. The adhesion between the magnetic label laminate and the bankbook base 7 is made stronger. By using these methods, a magnetic recording medium for a passbook magnetic stripe having a complicated pattern and excellent design can be produced.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples, and hereinafter, “parts” represent parts by mass.

Example 1
A 38 μm thick polyethylene terephthalate film is used as a support film that is a base for a magnetic label. Each of the following compositions a, b, and c is used on one side of this film, the colored layer is 4 μm, and the protective layer is dried and then the film The layers were sequentially formed so as to have a thickness of 2 μm. Thereafter, a composition of the following d was used on the opposite surface of the film on which the above constituent layers were applied and formed, and an adhesive layer was formed to be 30 μm. Then, this magnetic label laminate was cut into a predetermined width to produce a magnetic label tape.

(A: Composition for magnetic recording layer)
40 parts of Ba ferrite magnetic powder (manufactured by Toda Kogyo Co., Ltd., “MC-127”)
Acrylic copolymer resin 6 parts (“Acridic 52-666” manufactured by Dainippon Ink & Chemicals, Inc.) Resin produced using 35% by mass of 2-hydroxyethyl methacrylate with respect to all monomers. Resin with a structure that has no chlorine atom in the molecule.)
4 parts of polyurethane resin (manufactured by Dainippon Ink & Chemicals, "Pandex T-5206"; resin having a structure having no chlorine atom in the molecule)
MEK 20 parts Toluene 20 parts Cyclohexanone 8 parts Isocyanate compound 2 parts

(B: Composition for colored layer)
Aluminum powder 20 parts Cellulose derivative resin 7 parts (manufactured by Eastman Chemical Co., “CAB381-0.5”)
3 parts polyurethane resin (Dainippon Ink & Chemicals, “Pandex TR-01”)
MEK 35 parts Toluene 25 parts Ethyl acetate 10 parts

(c: Composition for protective layer)
16 parts acrylic resin (Dai Nippon Ink Chemical Co., Ltd. “KU-273”)
8 parts of talc pigment (Matsumura Sangyo “# 5000 PJ”)
Isocyanate curing agent 2 parts
("D-750" manufactured by Dainippon Ink & Chemicals, Inc.)
MEK 37 parts
37 parts of toluene

(D: Composition for pressure-sensitive adhesive layer)
Alkylphenol resin 6 parts
(Arakawa Chemical Industries, “Tamanol 100S”)
Acrylic ester / acrylic acid / vinyl acetate copolymer resin (Saiden Chemical Co., Ltd., “Cybinol SD-102”) 67 parts
26 parts of toluene
Isocyanate curing agent 1 part
(Nippon Polyurethane “Coronate L”)

  Next, after sticking the above magnetic label tape to a bankbook base (manufactured by Dynic Co., Ltd., “Magnaprene 702”), it is heated and pressurized for 2 seconds at a temperature of 110 ° C. and a pressure of 0.1 MPa. A bankbook base was prepared. Then, the magnetic stripe part was cut out to 7 mm x 14 mm, and the sample for a magnetic characteristic measurement was created.

(Comparative Example 1)
Prepare the magnetic label tape in the same manner as in the examples except that the composition of the coating composition for the magnetic recording layer is as follows. did.

(G: Composition for magnetic recording layer)
40 parts of Ba ferrite magnetic powder
(Toda Kogyo Co., Ltd. “MC-127”)
Acrylic copolymer resin 6 parts (Rohm & Haas, “Paraloid AU-1164”; resin produced using 1-5% of 2-hydroxyethyl methacrylate with respect to all monomers. In the molecule Resin with no chlorine atom.)
4 parts of polyurethane resin (manufactured by Dainippon Ink & Chemicals, "Pandex T-5205"; resin with a structure having no chlorine atom in the molecule)
Isocyanate curing agent 2 parts
(Nippon Polyurethane “Coronate L”)
MEK 20 parts
20 parts of toluene
10 parts of cyclohexanone

(Test items and results)
1. Magnetic properties (magnetic powder dispersibility)
With the obtained laminate sheet for thermal transfer, the magnetic static characteristics were measured (manufactured by Riken Electronics Co., Ltd .: VSM was used), and the “square ratio (Br / Bm)” was measured under the condition of a maximum applied magnetic field of 800 kA / m (10053 Oersted). Asked.

2. Presence / absence of chlorine in the layer structure Table 1 shows the results of elemental mapping by SEM-EDS.

  As shown in Example 1, according to the present invention, the magnetic recording medium desalted according to the present invention does not contain chlorine derived from the material. However, even with respect to chlorine derived from impurities, the element mapping method by SEM-EDS No chlorine was detected from the layer structure. However, even when the magnetic recording medium having the structure of the embodiment is used, the squareness ratio is equivalent to that of the conventional vinyl chloride magnetic recording medium, so that the dispersibility of the magnetic powder is the same as that of the conventional vinyl chloride copolymer. It can be seen that it is as good as coalescence.

Schematic of a passbook with a magnetic stripe. The cross-section figure of a magnetic label laminated body. The cross-section figure of the magnetic stripe part of the passbook which formed the magnetic stripe on the base for passbooks by the affixing method using a magnetic label laminated body.

Explanation of symbols

A Passbook substrate B Magnetic stripe 1 Magnetic label substrate 2 Magnetic recording layer 3 Colored layer 4 Protective layer 5 Adhesive layer 6 Release paper

Claims (5)

A nonmagnetic support; a magnetic recording layer formed on one surface of the nonmagnetic support; and an adhesive layer formed on a surface of the nonmagnetic support opposite to the surface on which the magnetic recording layer is formed. A magnetic recording medium comprising:
The magnetic recording layer is a layer in which barium ferrite powder having a BET specific surface area of ^{2 to} 9 m ² / g is finely dispersed in a binder resin containing an acrylic resin.
The acrylic resin has the formula (1) in the molecule.

(1)
(Wherein, R1 represents a hydrogen atom or a methyl group, R2 represents. An alkylene group which may having 2 to 8 carbon atoms which may have a branched chain) monomeric Ru compound der represented by a total monomer resin obtained by copolymerizing a radical polymerizable monomer containing 30 to 40 wt% with respect to body, and passbook, characterized in that in its molecule is a resin of a structure having no chlorine atom Magnetic recording medium. The magnetic recording medium for passbook according to claim 1, wherein the magnetic recording layer further contains a polyurethane resin having a structure having no chlorine atom in the molecule. 3. The passbook magnetic recording medium according to claim 1, wherein a colored layer for concealing the magnetic recording layer and a protective layer having a surface protecting function are formed in this order on the magnetic recording layer. A booklet to which the magnetic recording medium according to claim 1 is attached. A passbook to which the magnetic recording medium according to claim 1 is affixed.

Images