JP2840318B2 - Magnetic card - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic card, and more particularly, to a magnetic card which is excellent in dimensional stability against heat and appearance and which is strong.

[Prior Art and Problems to be Solved by the Invention] Conventionally, as a substrate film of a magnetic card, a polyvinyl chloride-based film and a polyester-based film have been known. However, a polyvinyl chloride-based base film has low heat resistance and low stiffness. On the other hand, polyester base films have practical problems such as insufficient whiteness and too high gloss.

By the way, a stretched film made of a stinlen-based polymer having a syndiotactic structure, developed by the present inventors, has excellent heat resistance, chemical resistance, and electrical insulation. However, even if a magnetic card is produced using this stretched film as a base film, the whiteness is insufficient and the gloss is too high.

Therefore, the present inventors have conducted intensive studies to develop a magnetic card that can sufficiently withstand practical use by using the styrene-based polymer having the syndiotactic structure.

[Means for solving the problem]

As a result, a magnetic layer is formed on a base film having a linear expansion coefficient, whiteness, and thickness within a certain range, in addition to a composition in which white inorganic particles are mixed in a certain ratio with the styrene polymer having the syndiotactic structure. Has been found to be a magnetic card suitable for the above purpose. The present invention has been completed based on such findings.

That is, the present invention provides 40 to 99% by weight of a styrenic polymer having a syndiotactic structure and 60 to 1% of white inorganic particles.
% Of a base film having a coefficient of linear expansion of 7 × 10 ⁻⁵ / ° C. or less, a whiteness of 80 or more, and a thickness of 50 to 1000 μm. An object of the present invention is to provide a magnetic card having a magnetic layer.

In the present invention, a single-layer film composed of a film of the above-described composition or a laminated film containing the film is used as the base film of the magnetic card. The base film has a linear expansion coefficient of 7 × 10 ⁻⁵ / ° C. or less, a whiteness of 75 or more, preferably 80 or more, and a thickness of 50 to 50 ° C.
It is 1000 μm, preferably 75-800 μm. Here, if the coefficient of linear expansion of the base film exceeds 7 × 10 ⁻⁵ / ° C., the temperature change in the recording / reproducing state is conspicuous, which is not preferable. On the other hand, if the whiteness is less than 75, clear characters and pictures cannot be obtained, which is not preferable for practical use. Regarding the thickness, if the thickness is less than 50 μm, the strength, durability and holding properties are insufficient, while if it is too thick, the workability, handling properties and flexibility are undesirably reduced.

In addition, in order to suppress deformation during processing and use, it is more preferable that the base film has a heat shrinkage of 2% or less at 200 ° C.

Further, the surface of the film may be subjected to a corona treatment or the like in consideration of the adhesiveness with the magnetic layer, the adhesive layer, and the like.

In order to obtain the above-mentioned base film, a composition obtained by adding white inorganic particles to a styrene polymer having a syndiotactic structure is used as a film, or this composition is laminated on another film surface. It may be provided in the form of a film by coating or the like, or a combination thereof. Most preferably, the styrene-based polymer composition having a syndiotactic structure to which white inorganic particles are added is biaxially stretched.When adding the white inorganic particles, the white inorganic particles may be added in any process during the polymerization. A method of blending, a method of blending after polymerization, and a method of blending a master batch are effectively applied.

The composition used as the material of the base film of the present invention comprises 40 to 99% by weight of a styrene polymer having a syndiotactic structure and 60 to 1% by weight of white inorganic particles. When the amount of the white inorganic particles exceeds 60% by weight, the obtained magnetic card has a high elastic modulus, but is brittle and cannot be used. Further, if the composition exceeds 60% by weight, stretching is difficult, and improvement in toughness by stretching cannot be expected. If the content is less than 1% by weight, the desired whiteness of the magnetic card cannot be exhibited.

By the way, the styrene-based polymer having a syndiotactic structure is a syndiotactic structure having a stereochemical structure, that is, a phenyl group or a substituted phenyl group which is a side chain with respect to a main chain formed from carbon-carbon bonds. It has a three-dimensional structure alternately positioned in the reaction direction, and its tacticity is determined by the magnetic resonance method ( ¹³ C-NMR) using isotope carbon.
Method). Tacticity measured by the ¹³ C-NMR method can be represented by the abundance ratio of a plurality of continuous structural units, for example, a dyad for two, a triad for three, and a pentad for five. However, the styrenic polymer having a syndiotactic structure referred to in the present invention is usually 75% or more, preferably 85% or more in a racemic diad, or a racemic pentad.
Polystyrene, poly (alkylstyrene), poly (halogenated styrene), poly (alkoxystyrene), poly (vinylbenzoate) having a syndiotacticity of 30% or more, preferably 50% or more, A coalescent and a mixture thereof, or a copolymer containing these structural units is referred to. Here, poly (alkylstyrene) includes poly (methylstyrene), poly (ethylstyrene), poly (propylstyrene), poly (butylstyrene, poly (phenylstyrene), poly (vinylnaphthalene), and poly (vinyl). Styrene), poly (acenaphthylene) and the like. Poly (halogenated styrene) includes poly (chlorostyrene),
Examples include poly (bromostyrene) and poly (fluorostyrene). Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene). Of these, particularly preferred styrene polymers include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tert-butylstyrene), poly (p-chlorostyrene), and poly (p-chlorostyrene). m-chlorostyrene), poly (p-fluorostyrene), and a copolymer of styrene and p-methylstyrene (JP-A-62-187708).

Further, as the comonomer in the styrenic copolymer, in addition to the styrenic polymer monomer as described above, olefin monomers such as ethylene, propylene, butene, hexene, and octene; diene monomers such as butadiene and isoprene; and cyclic diene monomers. Examples include polar vinyl monomers such as methyl methacrylate, maleic anhydride, and acrylonitrile.

The molecular weight of the styrenic polymer is not particularly limited, but is preferably 10,000 to 3,000,000, more preferably 50,000 to 1,500,000. Where the weight average molecular weight is 10,000
If it is less than 100%, stretching cannot be performed sufficiently. Further, the molecular weight distribution is not limited in its width and may be any of various types. However, the weight average molecular weight (Mw) / number average molecular weight (Mn) is preferably 1.5 or more and 8 or less. In addition,
The styrene-based polymer mainly having a syndiotactic structure has much better heat resistance than a conventional styrene-based polymer having an atactic structure.

On the other hand, together with the styrene-based polymer, as the white inorganic particles forming the composition that is the material of the base film,
Although there are various types, preferably, the periodic table IIa, IIb, II
A compound comprising at least one element selected from the group consisting of Ib, IVa, IVb, Vb, VIa and VIIa, for example, magnesium oxide, aluminum oxide, silicon oxide, titanium oxide, calcium carbonate, barium sulfate, Examples include magnesium carbonate, calcium silicate, talc, and the like, and mixtures thereof. The average particle size of the white inorganic particles is not particularly limited, but is preferably from 0.03 μm to 5 μm. The compounding amount is as described above, but in particular, in the case of a single-layer film, it is preferably 1 to 40% by weight, more preferably 3 to 30% by weight. In the case of lamination or coating, the content is preferably 5 to 60% by weight, more preferably 8 to 55% by weight. However, if the styrene-based polymer is whitened during stretching like a p-methylstyrene homopolymer and a white film is obtained, the addition amount may be small and 1 to 20% by weight is sufficient.

The resin component of the composition constituting the base film of the present invention is basically a styrene-based polymer having the above-mentioned syndiotactic structure.
In consideration of surface properties and the like, other resins and the like can be appropriately compounded as long as the object of the present invention is not impaired.

Here, there are various resins as the other resin. For example, the styrene-based polymer having an atactic structure, the styrene-based polymer having an isotactic structure, and polyphenylene ether are the styrene-based polymers having a syndiotactic structure. It is easy to be compatible with coalescence, is effective in controlling crystallization when preparing a preform for stretching, improves stretchability thereafter, easily controls stretching conditions, and provides a film with excellent mechanical properties. Obtainable. Among them, when a styrenic polymer having an atactic structure and / or an isotactic structure is contained, a styrene-based polymer having a syndiotactic structure is preferably used. The content ratio of these compatible resin components may be 70 to 1% by weight, particularly preferably 50 to 2% by weight. Here, when the content ratio of the compatible resin component is more than 70% by weight, heat resistance and the like, which are advantages of the styrene-based polymer having a syndiotactic structure, are not preferable. Examples of the incompatible resin include polyolefins such as polyethylene, polypropylene, polybutene, and polypentene; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon-6 and nylon 6,6; and polyphenylene. Polythioethers such as sulfide, polycarbonate, polyarylate, polysulfone, polyetheretherketone, polyethersulfone, polyimides, halogenated vinyl polymers such as Teflon, acrylic polymers such as polymethylmethacrylate, polyvinyl alcohol, etc. All correspond except for the compatible resin, and further include a crosslinked resin containing the above compatible resin. Since these resins are incompatible with the syndiotactic-structured styrene-based polymer of the present invention, if they are contained in small amounts, they can be dispersed like islands in the syndiotactic-structured styrene-based polymer. , Give a good gloss after stretching,
It is effective for improving the surface slip property. The content ratio of these incompatible resin components is 50 for the purpose of gloss.
~ 2% by weight, 0.001 ~
5% by weight is preferred. When the temperature used as a product is high, it is preferable to use a relatively heat-resistant incompatible resin. Here, when the incompatible resin is used, the addition amount of the white inorganic particles can be suppressed to a relatively small amount.

Further, in the present invention, a stabilizer, an antioxidant, a lubricant, a whitening agent, an ultraviolet absorber, a matting agent, and other various additives can be added to the composition as required.

To mold the base film of the magnetic card of the present invention,
According to the method as described above, the operation from the heat melting to the heat fixing performed at this time is specifically described as follows.

First, a molding material as described above is usually extruded (or co-extruded) to obtain a preform for stretching (film, sheet or tube). In this molding, it is common to heat-melt the above-mentioned molding material into a predetermined shape using an extruder, but without heating and melting the molding material, molding the softened state. Is also good. The extruder used here may be either a single-screw extruder or a twin-screw extruder, and may or may not have a vent, but a single-screw in-line tandem type is preferred. In addition, if an appropriate mesh is used for the pressing machine, impurities and foreign substances can be removed. In particular, when preparing a stretched film having a smooth surface, the mesh is preferably 100 mesh or more, and most preferably 400 mesh or more. Here, when these meshes are used, the following counts may be added before and after considering the pressure resistance and strength of the mesh itself. The shape of the mesh can be appropriately selected and used, such as a flat plate shape or a cylindrical shape.

The extrusion conditions are not particularly limited and may be appropriately selected according to various situations.Preferably, the temperature is selected in a range of from the melting point of the forming material to a temperature 50 ° C. higher than the decomposition temperature, and the shear stress is adjusted. 5 × 10 ⁶ dyne / cm ² or less. The die to be used includes a T-die, a ring die and the like.

After the extrusion molding, the obtained preform for stretching is cooled and solidified. Various refrigerants such as gas, liquid, and metal roll can be used as the refrigerant at this time. When using metal rolls, air knives, air chambers, touch rolls,
According to the method of applying static electricity or the like, it is effective for preventing thickness unevenness and waviness.

The temperature of cooling and solidification is usually in the range of 0 ° C. to a temperature 30 ° C. higher than the glass transition temperature of the preform for stretching, preferably 20 ° C.
C to the glass transition temperature. The cooling rate is 200
３3 ° C./sec.

Next, the cooled and solidified preform is uniaxially or biaxially stretched. In the case of biaxial stretching, the film may be stretched simultaneously in the machine direction and the transverse direction, but may be sequentially stretched in any order. The stretching may be performed in one step or may be performed in multiple steps.

Here, there are various stretching methods, such as a tenter method, a method of stretching between rolls, a method of bubbling using gas pressure, and a method of rolling, and these may be appropriately selected or combined and applied. The stretching temperature may generally be set between the glass transition temperature and the melting point of the preform. The stretching speed is usually 1 × 10 to 1
× 10 ⁵ % / min, preferably 1 × 10 ³ to 1 × 10 ⁵ % / min. When a stretched film obtained by stretching under the above-mentioned conditions requires dimensional stability, heat resistance, and strength balance in the film plane at higher temperatures, it is preferable to further heat-fix. The heat setting can be carried out by a commonly used method. However, the stretched film is stretched, relaxed or restricted in a contracted state, and has a glass transition temperature to a melting point of the film, preferably 100 ° C. lower than the melting point. What is necessary is just to hold | maintain in the temperature range just before a melting point from the temperature for 0.5 to 120 seconds. The heat setting can be performed twice or more with the conditions changed within the above range.
The heat fixing may be performed in an atmosphere of an inert gas such as an argon gas or a nitrogen gas.

Further, if necessary, operations such as addition of inorganic particles and organic particles to the film, lamination of a roughened film, sand mud treatment, coating mat treatment and embossing may be appropriately applied.

The thus obtained base film of the present invention has a linear expansion coefficient of 7 × 10 ⁻⁵ / ° C. or less, a whiteness of 80 or more, and a thickness of 50 to 100.
It is 0 μm.

The magnetic card of the present invention has at least one magnetic layer formed on the base film, but may have an undercoat layer or a topcoat layer. Each of these layers is formed on all or a part of both surfaces or one surface with the base film as the center.

Further, there are various kinds of magnetic materials as a material of the magnetic layer, for example, Co, Co-O, Co-Cr, Co-V, Co-Ni, Co-P, Co-.
γFe ₂ O ₃ , Co-Ni-P, Co-Ni-N, Co-Ni-W, Co-Ni-Pt, C
oNi (Cr) / Cr, Fe, Fe-O, Fe-Ag, γFe ₂ O ₃ , Fe-Co, Ni, CrO
_{2 and the} like can be listed.

In order to form a magnetic layer on a substrate film using this magnetic material, various methods such as coating, vapor deposition, sputtering, and plating may be used, and operating conditions and the like may be appropriately selected according to a conventional method. .

The thickness of the magnetic layer is not particularly limited, but is generally 0.
The thickness is from 0.01 to 10 μm, especially from 0.5 to 10 μm for coating, from 0.01 to 1 μm for vapor deposition or sputtering, and from 0.1 to 5 μm for plating.

Examples of the resin for the binder used in the coating include a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinyl acetate partially saponified copolymer, and a vinyl chloride-vinyl acetate copolymer.
Vinylidene chloride copolymer, vinyl copolymers such as vinyl chloride-acrylonitrile, vinyl butyral, and vinyl formal; fibrous systems such as nitrocellulose and cellulose acetobutyrate; polycondensation systems such as saturated polyester, polyurethane polyamide and epoxy; butadiene -Synthetic rubber based on acrylonitrile copolymer, inorganic polymer based such as polyphosphazene, etc., and a crosslinking agent such as isocyanate compound may be used.

The surface of the magnetic card of the present invention thus obtained may be polished to prevent wear of the magnetic head.

〔Example〕

 Next, the present invention will be described in more detail based on examples.

Glass container of Reference Example 1 (1) trimethylaluminum with an inner volume of 500ml was prepared argon substitution of contact product of water, copper sulfate pentahydrate _{(CuSO 4 · 5H 2 O)} 17.8g (71 mmol), toluene 200 ml and trimethylaluminum 24 ml (250 mmol) were added and reacted at 40 ° C. for 8 hours. Thereafter, toluene was further distilled off from the solution obtained by removing the solid portion under reduced pressure at room temperature to obtain 6.7 g of a contact product. When the molecular weight of this contact product was measured by freezing point depression method, it was 610
Met.

(2) Production of styrene-based polymer In a reaction vessel having an inner volume of 2 were placed purified styrene 1, 5 mmol of the contact product obtained in (1) above as an aluminum atom, 5 mmol of triisobutylaluminum, and pentamethylcyclopentane. 0.025 mmol of dienyltitanium trimethoxide was added and a polymerization reaction was carried out at 90 ° C. for 5 hours. After the completion of the reaction, the product was decomposed with a methanol solution of sodium hydroxide to decompose the catalyst component, washed repeatedly with methanol, and dried to obtain 308 g of a polymer. When measured by gel permeation chromatography at 135 ° C. using 1,2,4-trichlorobenzene as a solvent, the weight average molecular weight of this polymer was 389,000, and the weight average molecular weight / number average molecular weight was 2,64. Was. Further, the polymer was confirmed to be a polystyrene having a syndiotactic structure by melting point and ¹³ C-NMR measurements.

Example 1 0.03 parts by weight of an optical brightener (OB-1 manufactured by Eastman Co.) and an average particle diameter of 0.9 were added to 100 parts by weight of the styrene-based polymer obtained in Reference Example 1 which was sufficiently dried under reduced pressure. 12 parts by weight of micronized particulate calcium carbonate (natural product, stearic acid surface treatment) was mixed for 1 minute with a super mixer, extruded with a device provided with a capillary die at the tip of a twin screw extruder, and cut into pellets.

The pellet was stirred under dry hot air at 120 ° C. These pellets were extruded at 320 ° C. using a device provided with a T-die at the tip of a single screw extruder. The extruded molten sheet was wound up through a touch roll type cooling metal roll. The temperature of the metal roll was 70 ° C and the average cooling rate was about 50 ° C / sec. The obtained preformed body having a thickness of 1000 μm was stretched three times between nip rolls having different peripheral speeds while being heated to 115 ° C. The stretching speed at this time was 6000% / min. Subsequently, the film was cured using a tenter at 120 ° C. and 3000% / min.
The film was stretched twice and subsequently heat-treated under tension at 250 ° C. for 20 seconds.

The thickness of this film was 120 μm, and the whiteness measured according to JIS L-1074 was 85. The coefficient of linear expansion from 0 to 90 measured by thermal mechanical analysis was 5 × 10 ⁻⁵ / ° C., and the thermal shrinkage after 30 minutes at 200 ° C. was 0.5%. The elastic modulus was 45000 kg / cm ² .

One surface of the base film thus obtained was subjected to a corona discharge treatment, and a magnetic paint was applied. The composition of this magnetic paint was 45 parts by weight of γ-Fe ₃ O ₃ magnetic powder, 17 parts by weight of vinyl chloride-vinyl acetate copolymer (VAGH, manufactured by UCC),
3.5 parts by weight of acrylonitrile-butadiene copolymer (N1432J, manufactured by Zeon Corporation), 1.5 parts by weight of polyisocyanate (Coronate L, manufactured by Nippon Polyurethanes), 50 parts by weight of methyl isobutyl ketone, 50 parts by weight of toluene, 4 parts by weight of carbon black It is. The thickness of the dried magnetic layer is 3 μm
Met.

A pattern was printed on the opposite surface of the magnetic layer, and input and output of information were tried. Also. There was no glare on the surface, and the printed surface had a clear and favorable appearance. Furthermore, the card had sufficient waist (elasticity), and even a temperature change of 0 to 100 ° C. did not affect its appearance and performance.

Example 2 Except that 42 parts by weight of titanium oxide (Taipek A-100) having an average particle size of 0.2 μm was used as white inorganic particles,
A magnetic card was obtained in the same manner as in Example 1. The elastic modulus of this card was 52000 kg / cm ² .

Comparative Example 1 The procedure of Example 1 was repeated except that the white inorganic particles were not used. The performance of the obtained magnetic card was the same as that of Example 1, but the slip property was poor, and printing was partially peeled off after repeated use. In addition, the appearance has glare,
The touch was poor and sticky, and the appearance was not favorable.

Comparative Example 2 An attempt was made in the same manner as in Example 1 except that 70% by weight of white inorganic particles was contained, but the film was broken during stretching, and no base film was obtained.

Comparative Example 3 A 100 μm thick vinyl chloride film containing 30% by weight of TiO ₂ was obtained, and this film was used in the same manner as in Example 1. The obtained magnetic card had insufficient heat resistance and dimensional stability.

Comparative Example 4 Intrinsic viscosity measured with o-chlorophenol solution at 35 ° C
Example 1 was repeated except that 0.61 polyethylene terephthalate was used. The obtained magnetic card had poor heat resistance and poor appearance, and particularly had glare on the surface, which was not preferable in terms of aesthetics. The elastic modulus of this card is 4000
It was 0 kg / cm ² .

 The above is summarized in the table.

[Effects of the Invention] As described above, the magnetic card of the present invention has necessary whiteness, is excellent in thermal dimensional stability and appearance, and is strong, and can withstand long-term use.

Therefore, the magnetic card of the present invention can be effectively used as various kinds of magnetic cards such as a prepaid card, a ticket, and a card key.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 5/704 G11B 5/80 B42D 15/10

Claims (2)

(57) [Claims] 1. A film of a composition comprising 40 to 99% by weight of a styrenic polymer having a syndiotactic structure and 60 to 1% by weight of white inorganic particles, or a laminated film containing the film, having a coefficient of linear expansion of 7 A magnetic card having a magnetic layer on at least one side of a base film having a density of not more than × 10 ^-5 / ° C, a whiteness of not less than 75 and a thickness of 50 to 1000 µm. 2. The magnetic card according to claim 1, wherein the film is a stretched film.