JPH07235036A - Antistatic easily stickable polyester film for magnetic card - Google Patents

Abstract

PURPOSE:To improve adhesive strength under shear and to impart high adhesive strength even to a magnetic coating material by forming a coating film with a specified aq. soln. contg. a specified polyester resin, a specified oxirane compd. and an antistatic agent. CONSTITUTION:This polyester film has a coating film formed on one side with an aq. coating soln. contg. a compsn. consisting of 40-85wt.% polyester resin having carboxylic acid groups and/or carboxylate groups in each molecular chain and 20-150 deg.C secondary transition temp., 5-30wt.% oxirane compd. having at least two oxirane groups in one molecule and 10-40wt.% antistatic agent. Since the polyester resin forming a crosslinked structure with the oxirane compd. is used as the principal binder in the coating film (primer layer), when a UV-curing ink layer is disposed, adhesive strength under shear is improved and high adhesive strength is exhibited even to a magnetic coating material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film for electrically antistatic adhesives for magnetic cards, more specifically a polyester resin having a carboxylic acid group and / or its base in the molecular chain, and two or more oxirane groups in the molecule. The present invention relates to an easily antistatic adhesive polyester film for magnetic cards, which has an excellent antistatic property and easy adhesion by using an aqueous coating liquid containing an oxirane compound having an antistatic agent.

[0002]

2. Description of the Related Art A white polyester film is used as a base film of a magnetic card, but the handling property is deteriorated or dust is liable to be attached due to the charge on the surface of the card. Further, the base film is required to have an adhesive force with respect to the magnetic paint and the printing ink, but when the antistatic property is imparted, the adhesive property with respect to these is often deteriorated (see JP-A-1-289838). In particular, the adhesive force becomes insufficient in durability against scratching by nails.

[0003]

An object of the present invention is to provide a polyester film for magnetic cards which has high solvent resistance, low surface resistivity, and excellent adhesion to magnetic paints and printing inks. To provide.

[0004]

The present invention has the following constitution in order to achieve the above object.

On at least one side of the polyester film,
(A) 40 to 85% by weight of a polyester resin having a carboxylic acid group and / or its base in the molecular chain and having a secondary transition point of 20 to 150 ° C., and (B) having at least two oxirane groups in the molecule. An electrically antistatic adhesive polyester film for a magnetic card, which is provided with a coating film using an aqueous coating solution containing 5 to 30% by weight of an oxirane compound and 10 to 40% by weight of an antistatic agent (C).

In the present invention, the polyester constituting the polyester film contains 70 mol% or more of the acid component, particularly 9
An aromatic polyester in which 0 mol% or more is an aromatic dicarboxylic acid, and examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-diphenyldicarboxylic acid. Examples of the glycol component include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol and the like. Specific examples of the aromatic polyester include polyethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate) and the like. Of these, polyethylene terephthalate and polyethylene-2,6-naphthalate are particularly preferable.

If desired, organic or inorganic fine particle lubricants, colorants, antistatic agents, antioxidants, optical brighteners and other resins can be added to the aromatic polyester.

As the fine particle lubricant, calcium carbonate, calcium oxide, titanium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, tin oxide, carbon black,
Examples of the fine particles include barium sulfate, silicon carbide, crosslinked acrylic resin, crosslinked polystyrene resin, melamine resin, crosslinked silicone resin and the like.

Examples of the colorant include titanium oxide, barium sulfate, calcium carbonate, silica and the like, but those having a white film and a low light transmittance, particularly those mainly containing titanium oxide are preferable. preferable.

Other resins that can reduce the density of the film, such as polyolefins and modified polyolefins, are preferred. Further, poly (4-methylpentene-1) can also be used.

In the present invention, the polyester film is preferably a biaxially oriented film. The polyester film can be manufactured by a conventionally known method. For example, it can be manufactured by a method in which an aromatic polyester is melt extruded from a die, rapidly cooled to give an unstretched film, and then the unstretched film is stretched biaxially simultaneously or successively and then heat set. At that time, the stretching treatment was carried out in the machine direction (Tg−10) to (Tg + 50) ° C. (however, T
g is the temperature of the secondary transition point of the aromatic polyester) and is 2.5
It is preferable that the film is stretched at a stretch ratio of ˜7.0 times and stretched in the transverse direction at a temperature higher than the longitudinal stretching temperature by 2.5 to 7.0 times. The area draw ratio is preferably 8 times or more. Also, the heat setting process is 1
It is preferably carried out at a temperature of 50 to 250 ° C.

In the present invention, the polyester resin (A) as a coating film forming component is a polyester resin having a carboxylic acid group and / or its base in the molecular chain. Here, the molecular chain means an end and / or a side chain of a polymer molecule. The base is preferably a thermally dissociable base, that is, a substance which is dissociated by heating to generate a free carboxylic acid group, such as an ammonium carboxylic acid base, a quaternary amine base, or a phosphonium base. It can also be a sodium base, a potassium base, a lithium base or the like. Among these, ammonium base and quaternary amine base are particularly preferable.

Examples of the acid component constituting this polyester resin include terephthalic acid, isophthalic acid, and 2,6-
Naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 5-K sulfoisophthalic acid, 5-Nasulfoisophthalic acid, phthalic acid, apicinic acid, sebacic acid, 1,4
-Cyclohexanedicarboxylic acid, dodecanedicarboxylic acid, trimellitic acid, trimesic acid and the like can be mentioned. These acid components are preferably used in combination with a dicarboxylic acid component and a trifunctional or higher polyvalent carboxylic acid component. Particularly, the polyvalent carboxylic acid component introduces a carboxylic acid group or a base thereof into a side chain of a polymer molecule. It is effective for The proportion of this polyvalent carboxylic acid component is 0.5 to 40 per total acid component.
It is preferably set to mol%.

As the polyhydric alcohol component constituting the polyester resin, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4
-Butanediol, neopentyl glycol, 1,6-
Hexanediol, diethylene glycol, triethylene glycol, 1,4-cyclohexanedimethanol,
Examples thereof include p-xylylene glycol, dimethylolpropionic acid, alkylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide copolymer, polytetramethylene glycol and the like. These can use 1 or more types, and it is preferable to use 2 or more types.

The polyester resin can be produced by a conventional method, for example, by reacting an acid component with a polyhydric alcohol component in a lump, liquid or aqueous system to carry out polyesterification. In that case, in addition to the above-mentioned acid component and polyhydric alcohol component, a small amount of unsaturated compounds such as maleic acid, fumaric acid, dimer acid, cinnamic acid, stilbene dicarboxylic acid, acetylene diol, polybutadiene diol, etc. can be used. Further, in order to introduce a carboxylate group into the side chain of a polymer molecule, a tri- or higher functional compound such as trimellitic acid, butanetetracarboxylic acid, trimesic acid, pyromellitic acid, succinic acid, trimellitic anhydride,
A carboxylic acid group (—COOH) is introduced into the side chain of the molecule using succinic anhydride, pyromellitic dianhydride, butanetetracarboxylic dianhydride, dimethylolpropionic acid, etc., and then at least part of the carboxylic acid group is introduced. Alternatively, it is preferable to use a method in which all of them are neutralized with amine, ammonia, alkylphosphine or the like. A part of the carboxylic acid group can be neutralized with an alkali metal compound or an alkaline earth metal compound. However, the carboxylate group obtained in this case merely acts to impart hydrophilicity, and its action is slightly different from that of the heat dissociable base.

The acid value of the polyester resin is 30 to 20.
It is preferably 0, particularly 35 to 150. The thermal dissociable base is converted into a carboxylic acid group and then the acid value is measured.

The second-order transition point of the polyester resin is 20.
The temperature is up to 150 ° C, preferably 40 to 100 ° C. If the second-order transition point is less than 20 ° C, blocking is likely to occur, while if it exceeds 150 ° C, the adhesiveness is deteriorated, which is not preferable.

In the present invention, examples of the oxirane compound (B) having at least two oxirane groups in the molecule of the coating film forming component include

[0019]

[Chemical 1]

[0020]

[Chemical 2]

[0021]

[Chemical 3]

[0022]

[Chemical 4]

[0023]

[Chemical 5]

[0024]

[Chemical 6]

[0025]

[Chemical 7]

[0026]

[Chemical 8]

[0027]

[Chemical 9]

[0028]

[Chemical 10]

[0029]

[Chemical 11]

[0030]

[Chemical 12]

[0031]

[Chemical 13]

[0032]

[Chemical 14]

[0033]

[Chemical 15]

And the like.

In the present invention, the antistatic agent (C) as a coating film forming component is a sulfonate group, a phosphate group,
Antistatic agents having at least one group selected from betaine groups, sulfate groups and quaternary nitrogen groups, specifically alkyl sulfonates, alkyl aryl sulfonates,
Betaine, alkyl ethosulfate, phosphate ester salt, quaternary ammonium salt, polystyrene sulfonate,
Preferable examples include quaternary amino group-containing acrylic copolymers, titanate-amino compound complexes, carbon black, tin oxide, antimony oxide-doped tin oxide, perchlorates, and polyalkylene oxide copolymers.

In the present invention, the polyester resin (A), the oxirane compound (B) and the antistatic agent (C)
As for the blending ratio of 100% by weight of these total amounts,
The polyester resin (A) is 40 to 85% by weight, the oxirane compound (B) is 5 to 30% by weight, and the antistatic agent (C) is 10 to 40% by weight. Preferably, the polyester resin (A) is 40 to 81% by weight, the oxirane compound (B) is 7 to 20% by weight, and the antistatic agent (C) is 1%.
It is 2 to 30% by weight. When the oxirane compound (B) is less than 5% by weight, the crosslinking is insufficient, while when it exceeds 30% by weight, the structure becomes brittle. Further, the antistatic agent (C) is 10% by weight.
If it is less than 40%, the antistatic property is insufficient, while if it exceeds 40% by weight, the adhesiveness is deteriorated.

The composition comprising the polyester resin (A), the oxirane compound (B) and the antistatic agent (C) includes a polyester resin (A) and an oxirane compound (B).
For the purpose of accelerating the (crosslinking) reaction of, a reaction accelerating compound (D) can be added.

Examples of the reaction accelerating compound (D) include tertiary amino group-containing compounds, compounds having a nitrogen-containing ring structure and salts thereof, quaternary ammonium salt compounds, and the like. More specifically, examples of the tertiary amino group-containing compound include trimethylamine, triethylamine, tri-n-butylamine, dimethylaminobenzene, benzyldimethylamine, and 2,4,6-tris (dimethylaminomethyl) phenol. be able to. The compound having a nitrogen-containing ring structure and a salt thereof,
For example, 2-methylimidazole, 2-methyl-4-ethylimidazole, 2-ethylimidazole, 2-isopropylimidazole, imidazole compound such as 2-phenyl-4-methylimidazole, 1,8-diazo-bicyclo (5,4,4) 0) Undecene-7 and their hydrochlorides, carbonates and the like. Examples of the quaternary ammonium salt compound include triethylbenzylammonium chloride and tetramethylammonium chloride. Of these, a tertiary amino group-containing compound and a compound having a nitrogen-containing ring structure are preferable. Especially 2,4,6-tris (dimethylaminomethyl)
Phenol, 2-methylimidazole, 2-methyl-4
-Ethylimidazole is preferred.

The ratio of the compound (B) to the reaction accelerating compound (D) is 0 to 60 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the former. If the proportion of this reaction accelerating compound is too large, it becomes difficult to control the reaction, and the stability of the coating liquid is reduced.

The aqueous coating liquid includes polyester resin (A),
In addition to the oxirane compound (B) having an epoxy group and the antistatic agent (C), other resins, lubricants, fillers, colorants, ultraviolet absorbers, antioxidants and the like can be added as required. . The aqueous coating solution may take any form such as an aqueous solution, an aqueous dispersion, and an emulsion, but these may contain a small amount of an organic solvent. The solid content concentration of the aqueous coating solution is
It can be set arbitrarily, but 1 to 12% by weight, and further 2 to 8
It is preferably set to wt%.

The aqueous coating solution in the present invention may be applied to either an unstretched film, a uniaxially stretched film or a biaxially stretched film, but a predetermined amount is applied to the uniaxially stretched film, dried and further stretched, followed by heating. A method of fixing the biaxially stretched film is preferable. The coating is applied to one side or both sides of the film. The reaction between the carboxylic acid group and the oxirane group proceeds in the drying after coating.

The thickness of the coating film is preferably 0.01 to 2 μm. The thickness of the polyester film is 50-
It is 300 μm. If the thickness of the film is less than 50 μm, the rigidity becomes insufficient, while if it exceeds 300 μm, it is difficult to form a uniform film.

The coating film-coated polyester film thus obtained has a surface resistivity of 10 ¹² Ω / □ at 50% RH.
It has the following antistatic properties, solvent resistance, and magnetic paint and U
It has excellent V-ink adhesion and is useful as a base film for magnetic cards.

[0044]

EXAMPLES The present invention will be described in more detail with reference to examples. Each characteristic value was measured by the following method.

1. Adhesion <Magnetic paint> The thickness of the coating after drying the evaluation paint on the primer coated polyester film with a Meyer bar is about 4μ.
It is applied so that the thickness becomes m and dried at 100 ° C. for 3 minutes. After that, aging was performed at 60 ° C. for 24 hours, and then Scotch tape No. 600 (3M) width 12.7 mm, length 1
Adhere 5 cm so that air bubbles do not enter, and JIS on this
It is leveled and brought into close contact with a manual load roll described in C2701 (1975), and cut into a tape width. These 180 °
Measure the strength when peeled.

[Evaluation paint] In terms of solid content, urethane resin Nipporan 2304 (manufactured by Nippon Polyurethane) 25 parts by weight PVC / vinyl acetate resin Eslec A (manufactured by Sekisui Chemical Co., Ltd.) 50 parts by weight Dispersant Resion P (manufactured by Riken Vitamin) 1 Part by weight Magnetic agent CTX-860 (manufactured by Toda Kagaku Co., Ltd.) 500 parts by weight are dissolved in a mixed solvent of methyl ethyl ketone / toluene / cyclohexanone to prepare a 40% solution, and the mixture is mixed with a sand glider 2
Disperse in time. After that, 25 parts by weight of Coronate L (in terms of solid content) as a cross-linking agent is added and well stirred to obtain a magnetic coating material.

<UV Ink> A 250 μm-thick polyester film is attached to the uncoated surface of the sample film with an adhesive. UV curable printing ink (flash dry FDO Beni AP made by Toyo Ink
After printing N) with an RI tester (manufactured by Ming Seisakusho),
Medium pressure mercury lamp (80W / cm, single lamp type: made by Nippon Batteries) UV
Curing is performed with a curing device, and a thickness of 7.0 μm U
Form a V ink layer. The UV ink layer is scratched with a nail and the degree of the lack is displayed in 5 levels (Good: 5 ...
1: evil).

2. Anti-static property (surface resistivity) The coated surface of the primer-coated polyester film is
After standing at ℃ × 50% RH for 24 hours, it is measured with a vibration capacitance type potentiometer TR-84M type (manufactured by Takeda Riken).

3. Solvent resistance Add 5 drops (about 0.1 cc) of tetrahydrofuran with a dropper onto the surface of the primer-coated polyester film,
Gauze is placed on it, a weight of 200 g is placed thereon, and the gauze is moved at a speed of about 1000 mm / min. After drying at room temperature, the one not treated with tetrahydrofuran and the one not treated with tetrahydrofuran are compared with each other by a 400 times interference micrograph, and the state of surface change of the primer is judged as follows. Almost no primer: × Almost no change in primer: ○ Minor changes in surface morphology: ○ to △ Significant changes in surface morphology: × to △ Intermediate changes in surface morphology : △

[Example 1] An unstretched sheet of polyethylene terephthalate (containing titanium oxide) having an intrinsic viscosity of 0.66 was stretched 3.5 times in the longitudinal direction, and then 2,6-
Naphthalenedicarboxylic acid (73 mol%)-isophthalic acid (20 mol%)-trimellitic acid (7 mol%)-ethylene glycol (40 mol%)-neopentyl glycol (40 mol%)-bisphenol A / ethylene oxide adduct ( 20 mol%) Polyester resin (Tg = 76 ° C.) obtained by neutralizing the copolymer with trimethylamine (A-
1) 53% by weight of an oxirane compound of the following formula (I) (B-
1)

[0051]

[Chemical 16]

10% by weight, 20% by weight of lithium dodecylbenzenesulfonate (C-1), 15% by weight of polyoxyethylene nonylphenyl ether and 2% by weight of 1,3,5-tris-dimethylaminophenol acetate salt. An aqueous coating solution containing the composition and having a solid content concentration of 10% by weight was applied by a roll coater, and then, while being dried by heating, it was stretched in the transverse direction by 4.0 times and heat-set at 230 ° C. to have a thickness of 188 μm.
m white biaxially stretched film was obtained. Coating thickness is 1.1μ
It was m. The characteristics of this film are shown in Table 1.

[Comparative Example 1] The same procedure as in Example 1 was carried out except that the aqueous coating solution was not applied. The properties of the obtained film are shown in Table 1.

[Examples 2 to 8 and Comparative Examples 2 and 3] Example 1
In the same manner, except that the coating material, its ratio, and the film thickness were changed as shown in Table 1. The obtained film properties are shown in Table 1.

[0055]

[Table 1]

Note) (Polyester: A-2) Terephthalic acid (71 mol%)
-Isophthalic acid (20 mol%)-trimesic acid (9 mol%)-diethylene glycol (15 mol%)-neopentyl glycol (70 mol%)-ethylene glycol (15 mol%) The copolymer was neutralized with ammonia. Polyester resin (Tg = 62 ° C.). (Oxirane compound: B-2) A compound represented by the following formula (II).

[0057]

[Chemical 17]

(Antistatic agent: C-2) Sodium polystyrene sulfonate

[0059]

According to the present invention, the primer layer (coating film)
However, since a polyester resin that forms a cross-linked structure with the oxirane compound is used as the main binder, the shear adhesive strength is improved when a UV ink layer is provided, and high adhesive strength with respect to magnetic paints is also shown. Since the agent is contained in the cross-linking structure, it has excellent antistatic properties, and because of the cross-linking structure, it has good solvent resistance and high durability in the card base treatment process, and is useful for magnetic cards. It is possible to provide a highly antistatic adhesive polyester film.

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Claims (4)

[Claims] 1. A polyester resin having (A) a carboxylic acid group and / or its base in a molecular chain and having a second-order transition point of 20 to 150 ° C. at 40 to 85% by weight, on at least one side of the polyester film, ( B) 5 to 30% by weight of oxirane compound having at least two oxirane groups in the molecule
And (C) an antistatic easy-adhesive polyester film for a magnetic card, which is provided with a coating film using an aqueous coating liquid containing 10 to 40% by weight of an antistatic agent. 2. The polyester resin (A) has an acid value (provided that
The polyester film as claimed in claim 1, wherein the base is a polyester resin having a carboxylic acid group and a carboxylic acid group) of 30 to 200. 3. The antistatic agent (C) is an antistatic agent having at least one group selected from a sulfonate group, a phosphate group, a betaine group, a sulfate group and a quaternary nitrogen group. Antistatic adhesive polyester film for magnetic cards. 4. The antistatic adhesive polyester film for magnetic cards according to claim 1, wherein the polyester is polyethylene terephthalate or polyethylene-2,6-naphthalate.