JPH06200062A - Polyester film for magnetic card - Google Patents

Abstract

PURPOSE:To provide a film which does not cause troubles due to generation and accumulation of static and is excellent in adhesion to a magnetic or print layer. CONSTITUTION:At least one side of a polyester film contg. a white pigment is coated with a resin compsn. which mainly comprises a thermally crosslinking monomer and a water-sol. ion-conductive resin obtd. by copolymerizing a monovinyl monomer having a cationic quaternary ammonium salt group on the side chain and a polymerizable double bond at the molecular end, a hydroxylated monovinyl monomer, and another copolymerizable vinyl monomer.

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 specifically, a magnetic card having excellent characteristics such as antistatic property and adhesion to a magnetic layer and a printing layer. For polyester film for use.

[0002]

2. Description of the Related Art Magnetic cards are widely used as cash cards and credit cards because they are so-called cashless conveniences, and financial institutions use automatic cash deposit / withdrawal. In addition, it is widely used in various fields such as ID cards, prepaid cards, telephone cards, and boarding cards, and it is expected that the applications of magnetic cards will further expand in the future.

A magnetic card has a magnetic layer and a printed layer displaying various information on the surface of a plastic sheet which has reduced light transmission. Since the plastic sheet that is the base material is required to have properties such as water resistance, chemical resistance, mechanical strength, and dimensional stability, a polyester film centered on polyethylene terephthalate, which is excellent in these properties, is mainly used. Is used for. The most serious 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, so that, for example, work efficiency such as winding around a roll in a process of applying a magnetic layer or a printing process, electric shock to a human body, and difficulty of handling. In addition to problems leading to deterioration, many problems such as the occurrence of print whiskers and stains on the film surface that lower the product value have occurred.

On the other hand, from the viewpoint of improving the durability of the magnetic card, it is required to further improve the adhesiveness between the polyester film and the magnetic layer and the printing layer. Therefore, various methods have been studied to improve the adhesiveness of the polyester film and to impart antistatic property. As a method of improving the adhesiveness, there are a method of treating the film surface with an actinic ray such as corona discharge, ultraviolet rays and plasma, and a method of applying an easily adhesive resin such as polyester, polyacrylic acid ester and polyurethane. Further, as a method of imparting antistatic property, a surfactant having antistatic property, an antistatic agent such as an ionic compound, or
There is a method of kneading or applying a conductive substance such as metal powder or metal oxide into polyester.

Of these methods, it is easy to add an antistatic agent or a conductive substance when 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
There is no problem with antistatic agents such as surfactants and ionic compounds that the antistatic property deteriorates in an environment of low humidity, but the antistatic property is required unless a large amount of conductive substance is added to the coating layer. Since the effect is not expressed, there is a problem that the effect of imparting adhesiveness is reduced. In addition, since the conductive material is expensive, there is a problem that the cost increases.
For these reasons, the method of using an antistatic agent is generally more common.

On the other hand, as a method for producing a biaxially stretched polyester film having a coating layer for imparting antistatic property and easy adhesion, a coating stretching method (in-line coating method) in which a coating solution is coated and then the film is stretched and heat-treated. There is something called. Compared with the method of forming a coating layer by coating a coating solution on a polyester film after biaxial stretching, this method performs film formation and coating of the film at the same time, so that a wide product can be obtained at a relatively low cost. In addition, it is a useful method because it has a feature that the adhesiveness between the coating layer and the polyester film as the substrate is good.

However, in the case of producing an antistatic polyester film by the in-line coating method,
In general, since the antistatic agent is thermally unstable, volatilization or thermal decomposition occurs in a heat treatment step such as stretching, and the expected antistatic effect is not often 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, although anionic and nonionic antistatic agents exhibit practical antistatic properties under high humidity, the effect of environmental humidity on antistatic properties is large, and antistatic properties deteriorate under low humidity. There was a problem.

Further, the addition of an antistatic agent causes a problem that the adhesiveness is deteriorated and the water resistance and solvent resistance of the coating layer are deteriorated. Currently, no polyester film having both antistatic property and antistatic property has been obtained.

[0009]

DISCLOSURE OF THE INVENTION 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 adhesiveness to a magnetic layer or a printing layer. It is intended to provide a polyester film for a magnetic card.

[0010]

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

[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. It is a polyester produced by polycondensation. For these polyesters, a method of directly reacting an aromatic dicarboxylic acid and glycol, a method of transesterifying an alkyl ester of an aromatic dicarboxylic acid and a glycol and then polycondensation, or a method of subjecting a diglycol ester of an aromatic dicarboxylic acid to polycondensation It is produced by a method such as condensation. Typical examples of such polyesters include polyethylene terephthalate, polybutylene terephthalate and polyethylene.
-2,6-naphthalate and the like can be mentioned. These polyesters may be homopolymers or copolymers of a third component, but ethylene terephthalate units, butylene terephthalate units or ethylene-2,6
-Naphthalate unit is 70 mol% or more, preferably 8
A polyester of 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 and prevent the printed layer from being seen from the back side when a polyester film is used as a magnetic card. As the white pigment, a thermoplastic resin in which a polyester-insoluble thermoplastic resin is dispersed in a sea-island shape to scatter light may be used, or an organic particle such as a crosslinkable polymer insoluble in polyester or an inorganic Particles may be used.

The thermoplastic resin insoluble in polyester can be used without limitation as long as it is insoluble in the above polyester, but it is one which dissolves at 300 ° C. or lower 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 resins and EP rubber; polystyrene, polystyrene such as styrene-acrylonitrile copolymer and styrene-butadiene-acrylonitrile copolymer. Examples of the resin include polyarylate resin, polycarbonate resin, polyacrylonitrile resin, and the like. Of these, polyolefin resins and polystyrene resins are particularly suitable.

Examples of organic particles such as cross-linked polymers 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, and titanium oxide and calcium carbonate can be preferably used.

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

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

To contain the white pigment in the polyester film, a method of adding it during the polyester polymerization step,
A method in which a white pigment is preliminarily kneaded into the polyester polymer using an extruder or the like, a method in which a white pigment is mixed in the extrusion step in the film manufacturing step, and the like can be adopted. In the polyester of the present invention, in addition to the above white pigment, it is possible to add a colorant, a light-proofing agent, a fluorescent agent, an antistatic agent, etc., depending on the application.

The polyester thus obtained is formed into a film by a known melt extrusion method, and then stretched between rolls having a speed difference (roll stretch) or stretched by gripping a clip and expanding. (Tenter stretching),
At least uniaxial orientation treatment is preferably performed by stretching (inflation stretching) by expanding by air pressure.

In the present invention, a monofunctional vinyl monomer (X) having a cation-type quaternary ammonium base in a side chain and 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 a monofunctional vinyl monomer (Y) having a hydroxyl group and another polymerizable vinyl monomer (Z) copolymerizable with X and Y It is an essential requirement that the coating film-forming resin composition containing the heat-crosslinkable monomer (B) as a main component is applied. By applying the coating film-forming resin composition to the surface of the polyester film, it is possible to impart adhesiveness and antistatic property at the same time.

Examples of the monofunctional vinyl monomer (X) having a cationic type quaternary ammonium base in the side chain and a polymerizable double bond in the terminal in the above ion conductive resin (A) include dimethyl. Aminoethyl acrylate quaternized product, dimethylaminoethyl methacrylate quaternized product, diethylaminoethyl acrylate quaternized product, diethylaminoethyl methacrylate quaternized product, methylethylaminoethyl acrylate quaternized product, methylethylaminoethyl methacrylate quaternized product, dimethylaminostyrene Examples thereof include quaternary compounds and methylethylaminostyrene quaternary compounds, and one or more of these can be used.

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

The above monofunctional vinyl monomer (X), monofunctional vinyl monomer (Y), and other polymerizable vinyl monomer (Z)
The ion-conductive resin (A) can be obtained by copolymerizing the above with a conventionally known radical polymerization, and the copolymerization ratio of these is in the range of 5/1 to 2/1 as the polymerization ratio of (Y + Z) / X. preferable. If this polymerization ratio exceeds 5/1, the water solubility of the ion conductive resin (A) will decrease, or a monofunctional vinyl for introducing a cation type quaternary ammonium salt group into the ion conductive resin (A). As a result, the ratio of the monomer (X) is reduced, so that a coating film excellent in antistatic property 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 tackiness and blocking properties of the obtained coating film increase.

The polymerization ratio of (X + Z) / Y is 10
The range of / 1 to 15/1 is preferable, and the polymerization ratio is 15
When it exceeds / 1, the monofunctional vinyl monomer (Y) having a hydroxyl group is reduced, and the number of hydroxyl groups serving as a crosslinking point with the below-mentioned thermally crosslinkable monomer (B) is reduced, resulting in insufficient crosslinking. 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 deteriorate.

The heat-crosslinkable monomer (B) which constitutes the coating film forming resin composition together with the ion conductive resin (A) is a monomer which is reactive with the hydroxyl group in the monomer (Y). It is not particularly limited as long as it is a body, but 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 ion conductive resin (A) and the thermally crosslinkable monomer (B) in the coating film forming resin composition of the present invention is such that A / B is 70/30 by weight. A range of 97/3 is preferred. When the blending ratio is less than 70/30, the heat-crosslinkable monomer (B) becomes excessive, so that the water resistance and solvent resistance of the resulting coating film are improved, but the antistatic property is deteriorated and Spreadability is reduced. If the blending ratio exceeds 97/3, the amount of the heat-crosslinkable monomer (B) decreases and the crosslinking reactivity decreases, so that the water resistance / solvent resistance of the coating film deteriorates, and also the coating film It is not preferable because the spreadability is lowered and the antistatic property is deteriorated.

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

In the present invention, since the ion conductive resin (A) is water-soluble, it is preferable to use the coating film-forming resin composition in an aqueous solution, but alcohol is used for the purpose of improving wettability with polyester. You may use together organic solvents, such as. Further, in the coating film forming resin composition, if necessary, other crosslinking agents, catalysts, wetting agents, etc. and ultraviolet absorbers, pigments, organic fillers, inorganic fillers, lubricants within a range that does not impair the object of the present invention. Agents, antiblocking agents, etc. may be added. It is also possible to improve the properties such as adhesiveness and blocking property by using other binder resins together.

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

The coating film-forming resin composition according to the present invention is applied to one surface of a polyester film because the antistatic property is exhibited not only on the applied surface but also on the non-coated surface only by applying it to one surface of the polyester film. If so, the antistatic performance of the film will be sufficiently excellent, but if it is applied to both sides, the adhesion to the magnetic layer or the printing layer will be improved on both sides. Also,
A method of applying the coating film forming resin composition on one surface and applying another binder resin layer having a property of improving adhesiveness to the surface opposite to the applied surface may be adopted.

The coating amount of the coating film-forming resin composition applied to the polyester film is preferably 0.01 to 5 g / m ² as the solid content present on the film after biaxial stretching. When the coating amount is less than 0.01 g / m ² , sufficient antistatic properties cannot be obtained, and when coating 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 application 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, for example, a corona discharge treatment is applied to the film to improve the coatability of the solution or the adhesion between the film and the coating film. It doesn't matter. Further, the wettability and adhesiveness of the film surface can be improved by further subjecting the coating layer to corona discharge treatment, corona discharge treatment under a nitrogen atmosphere, ultraviolet irradiation treatment, and 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 is within a range not departing from the spirit of the present invention. Modifications and implementations are included in the present invention. The measurement methods and evaluation methods performed in the examples are as follows.

Light transmittance According to JIS K6714, it was measured using a Poic integrating sphere type HTR meter (manufactured by Nippon Seimitsu Optical Co., Ltd.). Adhesiveness with Magnetic Paint A sample film was coated with the following magnetic paint under predetermined conditions, and then Scotch tape No. 10 mm wide and 10 cm long was applied to the coated surface. 610 (manufactured by 3M) is attached so as to prevent air bubbles from entering, and smoothed by a roll, and a tensile speed of 1 using a Tensilon manufactured by Toyo Baldwin at 23 ° C. and 50% RH.
Peel strength was determined by performing a 360 ° peel test at 000 cm / min. Adhesive area is 5 cm, and chuck distance is 8
cm.

(Preparation and coating method of magnetic coating material 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

The above magnetic coating composition for evaluation was mixed and dispersed by a ball mill for about 12 hours, and then 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 further mixed and dispersed for 30 minutes. Then, 10 parts by weight of an ethyl acetate solution (solid content: 75% by weight) of a triisocyanate compound was added and mixed and dispersed for 1 hour to prepare a magnetic coating material. This magnetic coating material was applied onto the sample film so that the thickness after drying was 3 μm, and subjected to a magnetic field orientation treatment.
It was dried at 0 ° C., then calendered, and further aged at 60 ° C. for 72 hours for curing reaction.

Adhesiveness with printing ink Cellular CCST 390 indigo (manufactured by Toyo Ink Mfg. Co., Ltd.) as a printing ink for cellophane was applied on a sample film by a gravure coater so that the thickness after drying was 3 μm, and the ink was dried. The adhesiveness of the film and the film was examined by a cellophane tape peel test. After sticking cellophane tape on the printed surface,
Keeping the film flat and peeling the cellophane tape in the direction of about 150 °, the remaining area of the ink on the printed surface of the sample film was measured by the image processor Luzex IID (manufactured by Nireco).
Was measured and displayed in%. The larger the remaining area, the better the adhesion.

Specific surface resistance: Takeda Riken specific resistance measuring device applied voltage of 500 V, 2
It was measured under the conditions of 3 ° C. and 50% RH. Charge decay property Using a static decay meter manufactured by ETS in the United States, a sample film is sandwiched between electrodes under the conditions of 23 ° C. and 35% RH, and a voltage of 5.0 KV is applied, and the load voltage is 5.0.
The electrode was grounded when it reached KV, and the decay time t ₉₉ from grounding until the load voltage reached 0.05 KV was measured.

Example 1 Methyl methacrylate (MMA) / ethyl acrylate (EA) / 2-hydroxyethyl methacrylate (HEMA) / dimethylaminoethyl methacrylate quaternary compound (DM) was used in a conventional manner in a weight composition ratio of 47/21 /.
Copolymerization was carried out at a ratio of 7/25 to obtain an aqueous solution of a water-soluble ion conductive resin. To this aqueous solution, glycerol polyglycidyl ether (GPGE) was added as an epoxy compound in an amount of 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. 5% by weight was added and mixed to obtain an aqueous solution of a resin composition for forming a coating film having a solid content of 7% by weight.

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

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.
The evaluation results of the characteristics are shown in Table 2. The light transmittances of these sample films were all 6%. Example 6 The apparent specific gravity containing closed cells was the same as in Example 1 except that polyethylene terephthalate containing 4% by weight of titanium oxide and 10% by weight of polystyrene resin was melt extruded. Of 1.23 and a light transmittance of 8% was obtained. The characteristics of this sample film are shown in Table 2.

Comparative Examples 1 to 3 Sample films were prepared in the same manner as in Example 1 except that the composition of the coating film forming resin composition was changed as shown in Table 1. The characteristic evaluation results are shown in Table 2. Comparative Example 4 Same as Example 1 except that a solution obtained by mixing the 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 the coating liquid. Then, a sample film was prepared. The characteristic 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 coating film-forming resin composition was not applied. The characteristic evaluation results are shown in Table 2.

[0042]

[Table 1]

MMA: Methyl Methacrylate EA: Ethyl Acrylate HEMA: 2-Hydroxyethyl Methacrylate DM: Dimethylaminoethyl Methacrylate Quaternary GPGE: Glycerol Polyglycidyl Ether DPGGE: Diglycerol Polyglycidyl Ether * In Example 6, 4% by weight of titanium oxide Polyethylene terephthalate containing 10% by weight of polystyrene was used as a base film.

[0044]

[Table 2]

Each of the sample films obtained in Examples 1 to 6 had a low light transmittance, excellent adhesion to magnetic paints and printing inks, and excellent antistatic properties. . On the other hand, in Comparative Example 1, the spreadability of the coating film was poor and the coating was uneven. Also, the obtained film is inferior in both adhesiveness and antistatic property. The sample film of Comparative Example 2 had good adhesiveness but poor antistatic properties, and the sample film of Comparative Example 3 had good electrostatic properties but poor adhesiveness. Comparative Example 4 in which a commercially available antistatic agent was mixed and used
Both the sample film of No. 1 and the non-coated film of Comparative Example 5 were inferior in adhesiveness and antistatic property.

[0046]

Since the polyester film of the present invention contains a white pigment, light transmission is prevented and the printing effect can be exhibited when the magnetic card is used. Since a specific coating film-forming resin composition has been applied, a polyester film having improved anti-static properties, which has improved adhesion to the magnetic layer and the printing layer, and does not cause electrostatic damage due to the generation or accumulation of static electricity Could be provided. This polyester film is suitable as a base film for magnetic cards.

Claims (1)

[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 surface of a polyester film containing a white pigment ( X), a monofunctional vinyl monomer having a hydroxyl group (Y), and a water-soluble ionic conductive material 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 coating film-forming resin composition containing a resin (A) and a heat-crosslinkable monomer (B) as main components.