JP3269154B2 - Polyester film for magnetic card - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film provided with a magnetic layer and used as a magnetic card, and more particularly, to a magnetic card having excellent characteristics such as antistatic properties and adhesion to a magnetic layer and a printing layer. The present invention relates to a polyester film for use.

[0002]

2. Description of the Related Art Magnetic cards are widely used as cash cards and credit cards because of their so-called cashless convenience, and financial institutions use automatic payment and withdrawal of cash. In addition, the magnetic card is widely used in various fields as an ID card, a prepaid card, a telephone card, and a boarding card, and the use of the magnetic card is expected to further expand in the future.

A magnetic card is provided with a magnetic layer and a printed layer displaying various information on a plastic sheet surface with reduced light transmission. Since the plastic sheet used as the base material is required to have properties such as water resistance, chemical resistance, mechanical strength, and dimensional stability, polyester films mainly made of polyethylene terephthalate, which excel in these properties, are mainly used. It is used for The biggest problem when using this polyester film as a base material of a magnetic card is electrostatic damage. That is, since the polyester film is an insulator, static electricity is likely to be generated and accumulated because it is an insulator. For example, it is difficult to handle such as winding on a roll in a process of applying a magnetic layer or a printing process, electric shock to a human body, and difficulty in handling. Many troubles such as the occurrence of print mustaches and stains on the film surface and the like which lower the commercial value have occurred, including the troubles leading to the reduction.

On the other hand, from the viewpoint of improving the durability of a magnetic card, it is required to further improve the adhesion between the polyester film and the magnetic layer and the printing layer. For this reason, various methods have been studied to improve the adhesiveness of the polyester film and to impart antistatic properties. Examples of the method for improving the adhesiveness include a method of treating the film surface with an actinic ray such as corona discharge, ultraviolet light, or plasma, and a method of applying an easily adhesive resin such as polyester, polyacrylate, or polyurethane. Further, as a method of imparting antistatic properties, surfactants having antistatic properties, antistatic agents such as ionic compounds,
There is a method of kneading or applying a conductive substance such as metal powder or metal oxide into polyester.

[0005] Among these methods, it is easy to add an antistatic agent or a conductive substance at the time of applying the easily-adhesive resin to simultaneously impart adhesiveness and antistatic property to the coating layer. However, the method of adding a conductive substance is
It does not cause the problems of antistatic agents such as surfactants and ionic compounds that lower the antistatic properties in a low humidity environment, but the antistatic properties must be added unless a large amount of conductive material is added to the coating layer. There is a problem that the effect of imparting adhesiveness is reduced because the effect is not exhibited. In addition, there is also a problem that the cost increases because the conductive material is expensive.
For these reasons, the method using an antistatic agent is rather common.

On the other hand, as a method for producing a biaxially stretched polyester film having a coating layer for imparting antistatic properties and easy adhesion, a coating and stretching method in which a coating solution is applied and then the film is stretched and heat-treated (in-line coating method). There is something called. Compared with the method of applying a coating solution to a polyester film after biaxial stretching and forming a coating layer, this method can obtain a wide product relatively inexpensively because the film is formed and applied simultaneously. However, it is a useful method because it has characteristics such as obtaining a film having good adhesion between the coating layer and the polyester film of the substrate.

However, when producing an antistatic polyester film by an in-line coating method,
In general, since an antistatic agent is thermally unstable, volatilization or thermal decomposition occurs in a heat treatment step such as stretching, so that an expected antistatic effect is often not exhibited. Therefore, conventionally, a method has been adopted in which an anionic or nonionic compound having good thermal stability is mixed with a binder resin and applied. However, anionic or nonionic antistatic agents exhibit practical antistatic properties under high humidity, but the effect of environmental humidity on the antistatic properties is large, and the antistatic properties decrease under low humidity. There was a problem.

[0008] In addition, the addition of an antistatic agent causes problems such as a decrease in adhesiveness and a decrease in water resistance and solvent resistance of the coating layer. At present, a polyester film having both antistatic properties and antistatic properties has not been obtained.

[0009]

The present invention solves the above-mentioned problems of the prior art, does not cause static electricity damage due to generation and accumulation of static electricity, and has excellent adhesion to a magnetic layer or a printed layer. An object of the present invention is to provide a polyester film for a magnetic card.

[0010]

The polyester film for a magnetic card according to the present invention, which can solve the above-mentioned object, comprises a polyester film containing a white pigment and at least one side chain of a cationic quaternary ammonium. Monofunctional vinyl monomer (X) having a base and having a polymerizable double bond at a terminal, monofunctional vinyl monomer (Y) having a hydroxyl group, and copolymerizable with these monomers A water-soluble ionic conductive resin (A) obtained by copolymerizing another polymerizable vinyl monomer (Z) and a resin composition for forming a coating film containing a thermally crosslinkable monomer (B) as main components. It has a gist where it is applied. That is, the present invention, by applying the resin composition to a polyester film,
It has succeeded in simultaneously providing the antistatic property and improving the adhesive property.

[0011]

The polyester in the present invention is an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid or naphthalenedicarboxylic acid or an ester thereof, and a glycol such as ethylene glycol, diethylene glycol, 1,4-butanediol or neopentyl glycol. Polyester produced by polycondensation. These polyesters can be prepared by a method of directly reacting an aromatic dicarboxylic acid and a glycol, a method of subjecting an alkyl ester of an aromatic dicarboxylic acid to a transesterification reaction with a glycol and then a polycondensation, or a method of polymerizing a diglycol ester of an aromatic dicarboxylic acid. It is produced by a method of condensation and the like. Representative examples of such polyesters include polyethylene terephthalate, polybutylene terephthalate and polyethylene.
-2,6-naphthalate and the like. These polyesters may be homopolymers, or may be those obtained by copolymerizing a third component, and include ethylene terephthalate units, butylene terephthalate units or ethylene-2,6.
-Naphthalate units are at least 70 mol%, preferably 8
A polyester having 0 mol% or more, more preferably 90 mol% or more is used.

In the present invention, a white pigment is mixed in the polyester film. The white pigment is used to prevent the transmission of light rays when the polyester film is formed into a magnetic card so that the printed layer cannot be seen from the back surface. As the white pigment, a thermoplastic resin that disperses a thermoplastic resin insoluble in polyester in a sea-island manner and scatters light may be used, or organic particles such as a cross-linked polymer insoluble in polyester or inorganic particles may be used. Particles may be used.

As the thermoplastic resin insoluble in polyester, any thermoplastic resin which is insoluble in the above-mentioned polyester can be used without any limitation. It is a resin which is soluble at 300 ° C. or less and has good stability at the extrusion temperature. Is preferred. Specifically, polyolefin resins such as polyethylene, polypropylene and polymethylpentene; copolymerized polyolefin resins such as ionomer resin and EP rubber; polystyrene such as polystyrene, styrene-acrylonitrile copolymer and styrene-butadiene-acrylonitrile copolymer Resin; polyarylate resin; polycarbonate resin; polyacrylonitrile resin, and the like. Among these, polyolefin-based resins and polystyrene-based resins are particularly preferred.

Examples of the organic particles such as a crosslinked polymer include polystyrene particles, polyacrylic acid particles, and polysiloxane particles. Examples of the inorganic particles include talc, kaolin, barium sulfate, calcium carbonate, titanium oxide, and zeolite. Titanium oxide and calcium carbonate are preferably used.

These thermoplastic resins, organic particles and inorganic particles may be used alone or in combination of two or more. In particular, a single inorganic particle system or a combination of a thermoplastic resin and inorganic particles is preferred.

The content of the above white pigment in the polyester film is appropriately determined according to the type of the white pigment, the dispersion method, the thickness as a magnetic card substrate, the type of a magnetic card, and the like. As a polyester film before the installation, a Poic integrating sphere type according to JIS K6714
It is recommended that the light transmittance be 50% or less, preferably 40% or less, more preferably 20% or less when measured using an HTR meter (manufactured by Nippon Seimitsu Optical).

In order to incorporate a white pigment into a polyester film, a method of adding the white pigment during a polyester polymerization step is provided.
A method in which a white pigment is previously kneaded into the polyester polymer using an extruder or the like, a method in which the white pigment is mixed in the extrusion step in the film production step, and the like can be adopted. In addition to the above-mentioned white pigment, a coloring agent, a light-fast agent, a fluorescent agent, an antistatic agent and the like can be added to the polyester of the present invention depending on the use.

The polyester thus obtained is formed into a film by a known melt extrusion method, and then stretched between rolls having a further difference in speed (roll stretching), or stretched by being gripped and spread by clips. (Tenter stretching),
It is preferable that the film is at least uniaxially oriented by stretching (inflation stretching) by expanding by air pressure.

In the present invention, a monofunctional vinyl monomer (X) having a cationic quaternary ammonium base in a side chain and having a polymerizable double bond at a terminal is provided on at least one surface of the polyester film; Water-soluble ionic conductive resin (A) obtained by copolymerizing monofunctional vinyl monomer (Y) having a hydroxyl group with another polymerizable vinyl monomer (Z) copolymerizable with X and Y In addition, it is an essential requirement that a resin composition for forming a coating film containing a thermally crosslinkable monomer (B) as a main component is applied. By applying the resin composition for forming a coating film on the surface of a polyester film, it is possible to simultaneously impart adhesiveness and antistatic properties.

The monofunctional vinyl monomer (X) having a cationic quaternary ammonium base in the side chain and a polymerizable double bond at the terminal in the ionic conductive resin (A) is, for example, dimethyl Quaternary aminoethyl acrylate, quaternary dimethylaminoethyl methacrylate, quaternary diethylaminoethyl acrylate, quaternary diethylaminoethyl methacrylate, quaternary methylethylaminoethyl acrylate, quaternary methylethylaminoethyl methacrylate, dimethylaminostyrene A quaternary compound, a quaternary compound of methylethylaminostyrene, and the like, and one or more of these can be used.

Examples of the monofunctional vinyl monomer having a hydroxyl group (Y) include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate, which are copolymerizable with the above (X) and (Y). Other polymerizable vinyl monomers (Z) include alkyl acrylates such as methyl acrylate and ethyl acrylate, alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, styrene, vinyl toluene, vinyl acetate and the like. Vinyl monomer.

The above monofunctional vinyl monomer (X), monofunctional vinyl monomer (Y), and another polymerizable vinyl monomer (Z)
Is copolymerized by a conventionally known radical polymerization to obtain an ion-conductive resin (A), and the copolymerization ratio thereof is in a range of 5/1 to 2/1 as a polymerization ratio of (Y + Z) / X. preferable. When the polymerization ratio exceeds 5/1, the water solubility of the ionic conductive resin (A) decreases, or a monofunctional vinyl for introducing a cationic quaternary ammonium base into the ionic conductive resin (A). Since the ratio of the monomer (X) is consequently reduced, a coating film having excellent antistatic properties cannot be obtained. On the other hand, when the copolymerization ratio is less than 2/1, the water resistance of the coating film tends to decrease, and the resulting coating film has increased tackiness and blocking property.

The polymerization ratio of (X + Z) / Y is 10
/ 1 to 15/1 are preferable, and the polymerization ratio is 15
When the ratio exceeds / 1, the amount of the hydroxyl group-containing monofunctional vinyl monomer (Y) decreases, and the number of hydroxyl groups serving as crosslinking points with the thermally crosslinkable monomer (B) described below decreases, resulting in insufficient crosslinkability. Therefore, the water resistance and solvent resistance of the coating film decrease. On the other hand, when the polymerization ratio is less than 10/1, the number of hydroxyl groups becomes too large, and the water resistance and solvent resistance of the coating film also decrease.

The thermally crosslinkable monomer (B) constituting the resin composition for forming a coating film together with the ionic conductive resin (A) is a monomer having a reactivity with a hydroxyl group in the monomer (Y). Although it is not particularly limited as long as it is a body, an epoxy compound having 2 to 4 glycidyl groups is preferably used. Specific examples of such an epoxy compound include, for example, ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether,
Glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether and the like can be mentioned, and one or more of these can be used.

The mixing ratio of the ionic conductive resin (A) and the thermally crosslinkable monomer (B) in the resin composition for forming a coating film of the present invention is such that A / B is 70/30 to 70% by weight. A range of 97/3 is preferred. When the compounding ratio is less than 70/30, the heat-crosslinkable monomer (B) becomes excessive, so that the water resistance and solvent resistance of the obtained coating film are improved, but the antistatic property is deteriorated, The spreadability decreases. When the compounding ratio exceeds 97/3, the amount of the thermo-crosslinkable monomer (B) decreases and the crosslinking reactivity decreases, thereby deteriorating the water resistance and solvent resistance of the coating film. It is not preferable because the spreadability decreases and the antistatic property deteriorates.

In the present invention, when a coating film is formed using the above-mentioned resin composition for forming a coating film, the crosslinking reaction of the epoxy compound constituting the thermally crosslinkable monomer (B) is promoted. In addition, it is desirable to use a small amount of an organic or inorganic water-soluble alkali compound as a crosslinking accelerator, for example, amine, polyamine, amidoamine, polyamidoamine, imidazole, alkali metal carbonate, and derivatives thereof.

In the present invention, since the ion-conductive resin (A) is water-soluble, it is preferable to use the resin composition for forming a coating film in an aqueous solution, but it is preferable to use an alcohol for the purpose of improving the wettability with the polyester. May be used in combination. Further, in the resin composition for forming a coating film, if necessary, other crosslinking agents, catalysts, wetting agents, etc. and ultraviolet absorbers, pigments, organic fillers, inorganic fillers, lubricating agents, etc. within a range not to impair the object of the present invention. Agents, anti-blocking agents and the like may be added. Further, properties such as adhesion and blocking properties can be improved by using another binder resin in combination.

The polyester film for a magnetic card of the present invention is produced by applying a solution of the resin composition for forming a coating film to at least one surface of the polyester containing the white pigment. As a method of providing the coating layer, a commonly used method such as a gravure coat method, a kiss coat method, a dip method, a spray coat method, a curtain coat method, an air knife coat method, a spread coat method, and a reverse roll coat method can be applied.
As a step of applying, a method of applying in advance to a film surface before performing an orientation treatment, a method of applying the film to a film surface oriented in an axial direction and further orienting it in a perpendicular direction (in-line coating method), A method of coating the finished film surface or the like can be adopted. Among them, a method of applying the film to the surface of the film before the orientation treatment or an in-line coating method is particularly recommended because heat crosslinking at the time of the subsequent orientation treatment can simultaneously perform thermal crosslinking.

The resin composition for forming a coating film according to the present invention exhibits antistatic properties not only on the coated surface but also on the non-coated surface only by being coated on one surface of the polyester film. If this is the case, the antistatic performance of the film will be sufficiently excellent, but if it is applied to both sides, the adhesion to the magnetic layer and the print layer will improve on both sides. Also,
A method of applying the above-mentioned resin composition for forming a coating film on one surface and applying another binder resin layer having a property of improving adhesiveness to the surface opposite to the application surface may be adopted.

The amount of the solution of the resin composition for forming a coating film applied to the polyester film is preferably 0.01 to 5 g / m ² as a solid content present on the film after biaxial stretching. If the coating amount is less than 0.01 g / m ² , sufficient antistatic properties cannot be obtained, and if the coating amount is 5 g / m ² or more, blocking becomes a problem. The thickness of the polyester film itself used in the present invention is determined according to the use of the magnetic card, but generally 100 to 500 μm is preferably used.

Before applying the solution of the resin composition for forming a coating film, the coatability of the solution can be improved by, for example, subjecting the film to a corona discharge treatment, or the adhesiveness between the film and the coating film can be improved. It does not matter. The wettability and adhesion of the film surface can be improved by subjecting the coating layer to a corona discharge treatment, a corona discharge treatment in a nitrogen atmosphere, an ultraviolet irradiation treatment, or the like.

[0032]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples and it does not depart from the gist of the present invention. Changes and implementations are included in the present invention. In addition, the measuring method and the evaluation method performed in the Example are as follows.

Light transmittance was measured using a Poic integrating sphere HTR meter (manufactured by Nippon Seimitsu Kogaku) in accordance with JIS K6714. Adhesiveness to magnetic paint After coating the sample film with the following magnetic paint under predetermined conditions, a scotch tape No. 10 mm wide and 10 cm long was applied to the coated surface. 610 (manufactured by 3M) was stuck with a roll so that air bubbles did not enter, and a tensile speed of 1 was used at 23 ° C. and 50% RH using Tensilon manufactured by Toyo Baldwin.
Peel strength was determined by performing a 360 ° peel test at 000 cm / min. The bonding area is 5 cm, and the distance between chucks is 8
cm.

(Preparation and method of application of magnetic paint for evaluation) Co-γ-Fe ₂ O ₃ 100 parts by weight Vinyl chloride-vinyl acetate copolymer 15 parts by weight Urethane-modified saturated polyester resin 15 parts by weight α-alumina 3 parts by weight Carbon black 1 part by weight Toluene 105 parts by weight Methyl ethyl ketone 105 parts by weight Cyclohexanone 105 parts by weight

After mixing and dispersing the magnetic coating composition for evaluation for about 12 hours in a ball mill, 1 part by weight of palmitic acid, 2 parts by weight of dodecyl stearate and 2 parts by weight of oleic acid were added and mixed and dispersed for another 30 minutes. Then, 10 parts by weight of an ethyl acetate solution of a triisocyanate compound (solid content: 75% by weight) was added and mixed and dispersed for 1 hour to prepare a magnetic paint. This magnetic paint is applied on a sample film so as to have a thickness after drying of 3 μm, and is subjected to a magnetic field orientation treatment.
It was dried at 0 ° C., then calendered, and aged at 60 ° C. for 72 hours to effect a curing reaction.

Adhesiveness with printing ink Cellophane CCST 390 indigo (manufactured by Toyo Ink Mfg. Co., Ltd.) is applied as a printing ink for cellophane onto a sample film so as to have a thickness of 3 μm after drying with a gravure coater. The adhesiveness of the film and the film was examined by a cellophane tape peel test. After sticking cellophane tape on the printing surface,
The cellophane tape is peeled in a direction of about 150 ° while the film is kept flat, and the remaining area of the ink on the printed surface of the sample film is measured using an image processing device Luzex IID (manufactured by Nireco).
And measured in%. The larger the remaining area, the better the adhesion.

Surface resistivity: 500 V applied by a resistivity measurement device manufactured by Takeda Riken Co., Ltd.
The measurement was performed at 3 ° C. and 50% RH. Using a static decay meter manufactured by ETS in the United States, a sample film was sandwiched between the electrodes under a condition of 23 ° C. and 35% RH, a voltage of 5.0 KV was applied, and the charged voltage was 5.0.
Grounding the electrode was turned KV, it was measured decay time t ₉₉ from the Ground until the load voltage becomes 0.05KV.

Example 1 Methyl methacrylate (MMA) / ethyl acrylate (EA) / 2-hydroxyethyl methacrylate (HEMA) / dimethylaminoethyl methacrylate quaternary product (DM) was prepared by a conventional method at a weight composition ratio of 47/21 /
An aqueous solution of a water-soluble ionic conductive resin was obtained by copolymerization at a ratio of 7/25. To this aqueous solution, glycerol polyglycidyl ether (GPGE) as an epoxy compound was added at 4% by weight based on the solid content of the ion conductive resin, and 2-methylimidazole was added as a crosslinking accelerator to the glycerol polyglycidyl ether. An aqueous solution of the resin composition for forming a coating film having a solid content of 7% by weight was obtained by adding and mixing 5% by weight.

On the other hand, polyethylene terephthalate containing 5% by weight of titanium oxide is melt-extruded, and 3.
After stretching 0 times, an aqueous solution of the resin composition for forming a coating film was applied by a kiss coat method so as to be 10 g / m ² after drying, and dried with hot air at 70 ° C. Then stretched 3.0 times in the transverse direction, and heat-set at 200 to 210 ° C.
A sample film having a thickness of 250 μm after biaxial stretching was obtained. The light transmittance of this sample film was 6%. Table 2 shows other characteristics of the sample film.

Examples 2 to 5 Sample films were prepared in the same manner as in Example 1 except that the composition of the coating film forming composition was changed as shown in Table 1.
Table 2 shows the evaluation results of the characteristics. The light transmittance of each of these sample films was 6%. Example 6 An apparent specific gravity containing closed cells was obtained in the same manner as in Example 1 except that 4% by weight of titanium oxide and polyethylene terephthalate containing 10% by weight of a polystyrene resin were melt-extruded. Was 1.23, and a sample film having a light transmittance of 8% was obtained. Table 2 shows the properties of this sample film.

Comparative Examples 1 to 3 Sample films were prepared in the same manner as in Example 1 except that the composition of the resin composition for forming a coating film was changed as shown in Table 1. Table 2 shows the characteristic evaluation results. Comparative Example 4 Same as Example 1 except that a solution obtained by mixing a resin (A) of Comparative Example 2 in Table 1 and a commercially available anionic antistatic agent containing sodium sulfonate at a ratio of 8/2 was used as a coating solution. To prepare a sample film. The characteristics evaluation results are shown in Table 2. Comparative Example 5 A sample film was obtained in the same manner as in Example 1, except that the water solubility of the resin composition for forming a coating film was not applied. The characteristics evaluation results are shown in Table 2.

[0042]

[Table 1]

MMA: methyl methacrylate EA: ethyl acrylate HEMA: 2-hydroxyethyl methacrylate DM: dimethylaminoethyl methacrylate quaternary product GPGE: glycerol polyglycidyl ether DGPGE: diglycerol polyglycidyl ether * In Example 6, 4% by weight of titanium oxide And polyethylene terephthalate containing 10% by weight of polystyrene as a base film.

[0044]

[Table 2]

Each of the sample films obtained in Examples 1 to 6 had a low light transmittance, was excellent in adhesion to magnetic paints and printing inks, and was excellent in antistatic properties. . On the other hand, in Comparative Example 1, the spreadability of the coating film was poor and the coating was uneven. Further, the obtained film is inferior in both adhesiveness and antistatic property. The sample film of Comparative Example 2 had good adhesion but poor antistatic properties, and the sample film of Comparative Example 3 had good charging properties but poor adhesion. Comparative Example 4 using a commercially available antistatic agent
Each of the sample film and the uncoated film of Comparative Example 5 were inferior in adhesion and antistatic properties.

[0046]

Since the polyester film of the present invention contains a white pigment, light transmission is prevented and the effect of printing when a magnetic card is formed can be exhibited. In addition, since a specific coating film forming resin composition has been applied, the adhesion to the magnetic layer and the printing layer is improved, and a polyester film with excellent antistatic properties that does not cause static electricity damage due to generation or accumulation of static electricity. Could be provided. This polyester film is suitable as a base film for a magnetic card.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-248745 (JP, A) JP-A-5-1164 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 7/04-7/06 B32B 27/00-27/42

Claims (1)

(57) [Claims] 1. A monofunctional vinyl monomer having a cationic quaternary ammonium base in a side chain and a polymerizable double bond at a terminal on at least one side of a polyester film containing a white pigment. X), a monofunctional vinyl monomer having a hydroxyl group (Y), and a water-soluble ionic conductive compound obtained by copolymerizing another polymerizable vinyl monomer (Z) copolymerizable with these monomers. A polyester film for a magnetic card, which is obtained by applying a resin composition for forming a coating film containing a resin (A) and a thermally crosslinkable monomer (B) as main components.